Libraries: Move to Userland/Libraries/

Userland/Libraries/LibELF/Arch/i386/plt_trampoline.S

@@ -0,0 +1,58 @@
+/*-
+ * Copyright (c) 1998, 2002 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to The NetBSD Foundation
+ * by Christos Zoulas and by Charles M. Hannum.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/**
+ * This asm method is copied from NetBSD. We changed the internal method that
+ * gets called and the name, but it's still essentially the same as
+ * _rtld_bind_start from libexec/ld.elf_so/arch/i386/rtld_start.S
+ */
+
+.align	4
+	.globl	_plt_trampoline
+	.hidden	_plt_trampoline
+	.type	_plt_trampoline,@function
+_plt_trampoline:	# (obj, reloff)
+	pushf				# save registers
+	pushl	%eax
+	pushl	%ecx
+	pushl	%edx
+
+	pushl	20(%esp)		 # Copy of reloff
+	pushl	20(%esp)		 # Copy of obj
+	call	_fixup_plt_entry # Call the binder
+	addl	$8,%esp			 # pop binder args
+	movl	%eax,20(%esp)	 # Store function to be called in obj
+
+	popl	%edx
+	popl	%ecx
+	popl	%eax
+	popf
+
+	leal	4(%esp),%esp		# Discard reloff, do not change eflags
+	ret

Userland/Libraries/LibELF/AuxiliaryVector.h

@@ -0,0 +1,123 @@
+/*
+ * Copyright (c) 2020, The SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/String.h>
+#include <AK/Types.h>
+
+/* Auxiliary Vector types, from Intel386 ABI ver 1.0 section 2.3.3 */
+typedef struct
+{
+    long a_type; /* Note: Extended to long from int, for ease of comaptibility w/64 bit */
+    union {
+        long a_val;
+        void* a_ptr;
+        void (*a_fnc)(); /* In spec, not used */
+    } a_un;
+} auxv_t;
+
+// clang-format off
+#define AT_NULL 0           /* No length, last entry's a_type has this value */
+#define AT_IGNORE 1         /* Entry has no meaning, a_un undefined */
+#define AT_EXECFD 2         /* a_val contains a file descriptor of the main program image */
+#define AT_PHDR 3           /* a_ptr contains pointer to program header table of main program image */
+#define AT_PHENT 4          /* a_val holds size of program header table entries */
+#define AT_PHNUM 5          /* a_val holds number of program header table entries */
+#define AT_PAGESZ 6         /* a_val gives system page size in bytes */
+#define AT_BASE 7           /* a_ptr holds base address that Loader was loaded into memory */
+#define AT_FLAGS 8          /* a_val holds 1 bit flags. Undefined flags are 0 */
+#define AT_ENTRY 9          /* a_ptr holds entry point of the main program */
+#define AT_NOTELF 10        /* a_val non-zero if the program is not ELF */
+#define AT_UID 11           /* a_val holds real user id of process */
+#define AT_EUID 12          /* a_val holds effective user id of process */
+#define AT_GID 13           /* a_val holds real group id of process */
+#define AT_EGID 14          /* a_val holds effective group id of process */
+#define AT_PLATFORM 15      /* a_val points to a string containing platform name */
+#define AT_HWCAP 16         /* a_val contains bitmask of CPU features. Equivalent to CPUID 1.EDX*/
+#define AT_CLKTCK 17        /* a_val contains frequence at which times() increments. (Re: Spec. What is times()?) */
+#define AT_SECURE 23        /* a_val holds 1 if program in secure mode (e.g. suid). Otherwise 0 */
+#define AT_BASE_PLATFORM 24 /* a_ptr points to a string identifying base platform name, which might be different from platform (e.g x86_64 when in i386 compat)  */
+#define AT_RANDOM 25        /* a_ptr points to 16 securely generated random bytes */
+#define AT_HWCAP2 26        /* a_val holds extended hw feature mask. Currently 0 */
+#define AT_EXECFN 31        /* a_ptr points to file name of executed program */
+#define AT_EXE_BASE 32      /* a_ptr holds base address where main program was loaded into memory */
+#define AT_EXE_SIZE 33      /* a_val holds the size of the main program in memory */
+// clang-format on
+
+namespace ELF {
+
+struct AuxiliaryValue {
+    enum Type {
+        Null = AT_NULL,
+        Ignore = AT_IGNORE,
+        ExecFileDescriptor = AT_EXECFD,
+        Phdr = AT_PHDR,
+        Phent = AT_PHENT,
+        Phnum = AT_PHNUM,
+        PageSize = AT_PAGESZ,
+        BaseAddress = AT_BASE,
+        Flags = AT_FLAGS,
+        Entry = AT_ENTRY,
+        NotELF = AT_NOTELF,
+        Uid = AT_UID,
+        EUid = AT_EUID,
+        Gid = AT_GID,
+        EGid = AT_EGID,
+        Platform = AT_PLATFORM,
+        HwCap = AT_HWCAP,
+        ClockTick = AT_CLKTCK,
+        Secure = AT_SECURE,
+        BasePlatform = AT_BASE_PLATFORM,
+        Random = AT_RANDOM,
+        HwCap2 = AT_HWCAP2,
+        ExecFilename = AT_EXECFN,
+        ExeBaseAddress = AT_EXE_BASE,
+        ExeSize = AT_EXE_SIZE
+    };
+
+    AuxiliaryValue(Type type, long val)
+    {
+        auxv.a_type = type;
+        auxv.a_un.a_val = val;
+    }
+    AuxiliaryValue(Type type, void* ptr)
+    {
+        auxv.a_type = type;
+        auxv.a_un.a_ptr = (void*)ptr;
+    }
+    AuxiliaryValue(Type type, String string)
+    {
+        auxv.a_type = type;
+        auxv.a_un.a_ptr = nullptr;
+        optional_string = string;
+    }
+
+    auxv_t auxv {};
+    String optional_string;
+};
+
+}

Userland/Libraries/LibELF/CMakeLists.txt

@@ -0,0 +1 @@
+serenity_install_sources(Libraries/LibELF)

Userland/Libraries/LibELF/CoreDump.h

@@ -0,0 +1,87 @@
+/*
+ * Copyright (c) 2020, The SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/String.h>
+#include <AK/Types.h>
+#include <LibC/sys/arch/i386/regs.h>
+
+namespace ELF::Core {
+
+struct [[gnu::packed]] NotesEntryHeader {
+    enum Type : u8 {
+        Null = 0, // Terminates segment
+        ProcessInfo,
+        ThreadInfo,
+        MemoryRegionInfo,
+        Metadata,
+    };
+    Type type;
+};
+
+struct [[gnu::packed]] NotesEntry {
+    NotesEntryHeader header;
+    char data[];
+};
+
+struct [[gnu::packed]] ProcessInfo {
+    NotesEntryHeader header;
+    int pid;
+    u8 termination_signal;
+    char executable_path[]; // Null terminated
+};
+
+struct [[gnu::packed]] ThreadInfo {
+    NotesEntryHeader header;
+    int tid;
+    PtraceRegisters regs;
+};
+
+struct [[gnu::packed]] MemoryRegionInfo {
+    NotesEntryHeader header;
+    uint32_t region_start;
+    uint32_t region_end;
+    uint16_t program_header_index;
+    char region_name[]; // Null terminated
+
+    String object_name() const
+    {
+        StringView memory_region_name { region_name };
+        if (memory_region_name.contains("Loader.so"))
+            return "Loader.so";
+        if (!memory_region_name.contains(":"))
+            return {};
+        return memory_region_name.substring_view(0, memory_region_name.find_first_of(":").value()).to_string();
+    }
+};
+
+struct [[gnu::packed]] Metadata {
+    NotesEntryHeader header;
+    char json_data[]; // Null terminated
+};
+
+}

Userland/Libraries/LibELF/DynamicLinker.cpp

@@ -0,0 +1,287 @@
+/*
+ * Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
+ * Copyright (c) 2021, the SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <AK/HashMap.h>
+#include <AK/HashTable.h>
+#include <AK/LexicalPath.h>
+#include <AK/LogStream.h>
+#include <AK/ScopeGuard.h>
+#include <LibC/mman.h>
+#include <LibC/stdio.h>
+#include <LibC/sys/internals.h>
+#include <LibC/unistd.h>
+#include <LibCore/File.h>
+#include <LibELF/AuxiliaryVector.h>
+#include <LibELF/DynamicLinker.h>
+#include <LibELF/DynamicLoader.h>
+#include <LibELF/DynamicObject.h>
+#include <LibELF/Image.h>
+#include <LibELF/exec_elf.h>
+#include <dlfcn.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+// #define DYNAMIC_LOAD_VERBOSE
+
+#ifdef DYNAMIC_LOAD_VERBOSE
+#    define VERBOSE(fmt, ...) dbgprintf(fmt, ##__VA_ARGS__)
+#else
+#    define VERBOSE(fmt, ...) \
+        do {                  \
+        } while (0)
+#endif
+#define TLS_VERBOSE(fmt, ...) dbgprintf(fmt, ##__VA_ARGS__)
+
+namespace ELF {
+
+namespace {
+HashMap<String, NonnullRefPtr<ELF::DynamicLoader>> g_loaders;
+HashMap<String, NonnullRefPtr<ELF::DynamicObject>> g_loaded_objects;
+Vector<NonnullRefPtr<ELF::DynamicObject>> g_global_objects;
+
+using MainFunction = int (*)(int, char**, char**);
+using LibCExitFunction = void (*)(int);
+
+size_t g_current_tls_offset = 0;
+size_t g_total_tls_size = 0;
+char** g_envp = nullptr;
+LibCExitFunction g_libc_exit = nullptr;
+
+bool g_allowed_to_check_environment_variables { false };
+bool g_do_breakpoint_trap_before_entry { false };
+}
+
+DynamicObject::SymbolLookupResult DynamicLinker::lookup_global_symbol(const char* symbol_name)
+{
+    DynamicObject::SymbolLookupResult weak_result = {};
+    for (auto& lib : g_global_objects) {
+        auto res = lib->lookup_symbol(symbol_name);
+        if (res.found) {
+            if (res.bind == STB_GLOBAL) {
+                return res;
+            } else if (res.bind == STB_WEAK && !weak_result.found) {
+                weak_result = res;
+            }
+            // We don't want to allow local symbols to be pulled in to other modules
+        }
+    }
+    return weak_result;
+}
+
+static void map_library(const String& name, int fd)
+{
+    struct stat lib_stat;
+    int rc = fstat(fd, &lib_stat);
+    ASSERT(!rc);
+
+    auto loader = ELF::DynamicLoader::construct(name.characters(), fd, lib_stat.st_size);
+    loader->set_tls_offset(g_current_tls_offset);
+
+    g_loaders.set(name, loader);
+
+    g_current_tls_offset += loader->tls_size();
+}
+
+static void map_library(const String& name)
+{
+    // TODO: Do we want to also look for libs in other paths too?
+    String path = String::format("/usr/lib/%s", name.characters());
+    int fd = open(path.characters(), O_RDONLY);
+    ASSERT(fd >= 0);
+    map_library(name, fd);
+}
+
+static String get_library_name(const StringView& path)
+{
+    return LexicalPath(path).basename();
+}
+
+static Vector<String> get_dependencies(const String& name)
+{
+    auto lib = g_loaders.get(name).value();
+    Vector<String> dependencies;
+
+    lib->for_each_needed_library([&dependencies, &name](auto needed_name) {
+        if (name == needed_name)
+            return IterationDecision::Continue;
+        dependencies.append(needed_name);
+        return IterationDecision::Continue;
+    });
+    return dependencies;
+}
+
+static void map_dependencies(const String& name)
+{
+    VERBOSE("mapping dependencies for: %s\n", name.characters());
+
+    for (const auto& needed_name : get_dependencies(name)) {
+        VERBOSE("needed library: %s\n", needed_name.characters());
+        String library_name = get_library_name(needed_name);
+
+        if (!g_loaders.contains(library_name)) {
+            map_library(library_name);
+            map_dependencies(library_name);
+        }
+    }
+    VERBOSE("mapped dependencies for %s\n", name.characters());
+}
+
+static void allocate_tls()
+{
+    size_t total_tls_size = 0;
+    for (const auto& data : g_loaders) {
+        VERBOSE("%s: TLS Size: %zu\n", data.key.characters(), data.value->tls_size());
+        total_tls_size += data.value->tls_size();
+    }
+    if (total_tls_size) {
+        [[maybe_unused]] void* tls_address = ::allocate_tls(total_tls_size);
+        VERBOSE("from userspace, tls_address: %p\n", tls_address);
+    }
+    g_total_tls_size = total_tls_size;
+}
+
+static void initialize_libc(DynamicObject& libc)
+{
+    // Traditionally, `_start` of the main program initializes libc.
+    // However, since some libs use malloc() and getenv() in global constructors,
+    // we have to initialize libc just after it is loaded.
+    // Also, we can't just mark `__libc_init` with "__attribute__((constructor))"
+    // because it uses getenv() internally, so `environ` has to be initialized before we call `__libc_init`.
+    auto res = libc.lookup_symbol("environ");
+    ASSERT(res.found);
+    *((char***)res.address) = g_envp;
+
+    res = libc.lookup_symbol("__environ_is_malloced");
+    ASSERT(res.found);
+    *((bool*)res.address) = false;
+
+    res = libc.lookup_symbol("exit");
+    ASSERT(res.found);
+    g_libc_exit = (LibCExitFunction)res.address;
+
+    res = libc.lookup_symbol("__libc_init");
+    ASSERT(res.found);
+    typedef void libc_init_func();
+    ((libc_init_func*)res.address)();
+}
+
+static void load_elf(const String& name)
+{
+    VERBOSE("load_elf: %s\n", name.characters());
+    auto loader = g_loaders.get(name).value();
+    VERBOSE("a1\n");
+    for (const auto& needed_name : get_dependencies(name)) {
+        VERBOSE("needed library: %s\n", needed_name.characters());
+        String library_name = get_library_name(needed_name);
+        if (!g_loaded_objects.contains(library_name)) {
+            load_elf(library_name);
+        }
+    }
+
+    auto dynamic_object = loader->load_from_image(RTLD_GLOBAL | RTLD_LAZY, g_total_tls_size);
+    ASSERT(dynamic_object);
+
+    g_loaded_objects.set(name, *dynamic_object);
+    g_global_objects.append(*dynamic_object);
+
+    VERBOSE("load_elf: done %s\n", name.characters());
+}
+
+static NonnullRefPtr<DynamicLoader> commit_elf(const String& name)
+{
+    auto loader = g_loaders.get(name).value();
+    for (const auto& needed_name : get_dependencies(name)) {
+        String library_name = get_library_name(needed_name);
+        if (g_loaders.contains(library_name)) {
+            commit_elf(library_name);
+        }
+    }
+
+    auto object = loader->load_stage_3(RTLD_GLOBAL | RTLD_LAZY, g_total_tls_size);
+    ASSERT(object);
+    if (name == "libc.so") {
+        initialize_libc(*object);
+    }
+    g_loaders.remove(name);
+    return loader;
+}
+
+static void read_environment_variables()
+{
+    for (char** env = g_envp; *env; ++env) {
+        if (StringView { *env } == "_LOADER_BREAKPOINT=1") {
+            g_do_breakpoint_trap_before_entry = true;
+        }
+    }
+}
+
+void ELF::DynamicLinker::linker_main(String&& main_program_name, int main_program_fd, bool is_secure, int argc, char** argv, char** envp)
+{
+    g_envp = envp;
+
+    g_allowed_to_check_environment_variables = !is_secure;
+    if (g_allowed_to_check_environment_variables)
+        read_environment_variables();
+
+    map_library(main_program_name, main_program_fd);
+    map_dependencies(main_program_name);
+
+    VERBOSE("loaded all dependencies");
+    for ([[maybe_unused]] auto& lib : g_loaders) {
+        VERBOSE("%s - tls size: %zu, tls offset: %zu\n", lib.key.characters(), lib.value->tls_size(), lib.value->tls_offset());
+    }
+
+    allocate_tls();
+
+    load_elf(main_program_name);
+    auto main_program_lib = commit_elf(main_program_name);
+
+    FlatPtr entry_point = reinterpret_cast<FlatPtr>(main_program_lib->image().entry().as_ptr());
+    if (main_program_lib->is_dynamic())
+        entry_point += reinterpret_cast<FlatPtr>(main_program_lib->text_segment_load_address().as_ptr());
+
+    VERBOSE("entry point: %p\n", (void*)entry_point);
+    g_loaders.clear();
+
+    MainFunction main_function = (MainFunction)(entry_point);
+    VERBOSE("jumping to main program entry point: %p\n", main_function);
+    if (g_do_breakpoint_trap_before_entry) {
+        asm("int3");
+    }
+    int rc = main_function(argc, argv, envp);
+    VERBOSE("rc: %d\n", rc);
+    if (g_libc_exit != nullptr) {
+        g_libc_exit(rc);
+    } else {
+        _exit(rc);
+    }
+
+    ASSERT_NOT_REACHED();
+}
+
+}

Userland/Libraries/LibELF/DynamicLinker.h

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2021 (c), the SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/Result.h>
+#include <AK/Vector.h>
+#include <LibELF/DynamicObject.h>
+
+namespace ELF {
+
+class DynamicLinker {
+public:
+    static DynamicObject::SymbolLookupResult lookup_global_symbol(const char* symbol);
+    [[noreturn]] static void linker_main(String&& main_program_name, int fd, bool is_secure, int argc, char** argv, char** envp);
+
+private:
+    DynamicLinker() = delete;
+    ~DynamicLinker() = delete;
+};
+
+}

Userland/Libraries/LibELF/DynamicLoader.cpp

@@ -0,0 +1,530 @@
+/*
+ * Copyright (c) 2019-2020, Andrew Kaster <andrewdkaster@gmail.com>
+ * Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <AK/StringBuilder.h>
+#include <LibELF/DynamicLoader.h>
+#include <LibELF/Validation.h>
+
+#include <assert.h>
+#include <dlfcn.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+
+#ifndef DYNAMIC_LOAD_DEBUG
+#    define DYNAMIC_LOAD_DEBUG
+#endif
+
+// #define DYNAMIC_LOAD_VERBOSE
+
+#ifdef DYNAMIC_LOAD_VERBOSE
+#    define VERBOSE(fmt, ...) dbgprintf(fmt, ##__VA_ARGS__)
+#else
+#    define VERBOSE(fmt, ...) \
+        do {                  \
+        } while (0)
+#endif
+
+#ifndef __serenity__
+static void* mmap_with_name(void* addr, size_t length, int prot, int flags, int fd, off_t offset, const char*)
+{
+    return mmap(addr, length, prot, flags, fd, offset);
+}
+#endif
+
+namespace ELF {
+
+static bool s_always_bind_now = false;
+
+NonnullRefPtr<DynamicLoader> DynamicLoader::construct(const char* filename, int fd, size_t size)
+{
+    return adopt(*new DynamicLoader(filename, fd, size));
+}
+
+void* DynamicLoader::do_mmap(int fd, size_t size, const String& name)
+{
+    if (size < sizeof(Elf32_Ehdr))
+        return MAP_FAILED;
+
+    String file_mmap_name = String::format("ELF_DYN: %s", name.characters());
+    return mmap_with_name(nullptr, size, PROT_READ, MAP_PRIVATE, fd, 0, file_mmap_name.characters());
+}
+
+DynamicLoader::DynamicLoader(const char* filename, int fd, size_t size)
+    : m_filename(filename)
+    , m_file_size(size)
+    , m_image_fd(fd)
+    , m_file_mapping(do_mmap(m_image_fd, m_file_size, m_filename))
+    , m_elf_image((u8*)m_file_mapping, m_file_size)
+{
+
+    if (m_file_mapping == MAP_FAILED) {
+        m_valid = false;
+        return;
+    }
+
+    m_tls_size = calculate_tls_size();
+
+    m_valid = validate();
+}
+
+RefPtr<DynamicObject> DynamicLoader::dynamic_object_from_image() const
+{
+    VirtualAddress dynamic_section_address;
+
+    m_elf_image.for_each_program_header([&dynamic_section_address](auto program_header) {
+        if (program_header.type() == PT_DYNAMIC) {
+            dynamic_section_address = VirtualAddress(program_header.raw_data());
+        }
+        return IterationDecision::Continue;
+    });
+    ASSERT(!dynamic_section_address.is_null());
+
+    return ELF::DynamicObject::construct(VirtualAddress(m_elf_image.base_address()), dynamic_section_address);
+}
+
+size_t DynamicLoader::calculate_tls_size() const
+{
+    size_t tls_size = 0;
+    m_elf_image.for_each_program_header([&tls_size](auto program_header) {
+        if (program_header.type() == PT_TLS) {
+            tls_size = program_header.size_in_memory();
+        }
+        return IterationDecision::Continue;
+    });
+    return tls_size;
+}
+
+bool DynamicLoader::validate()
+{
+    auto* elf_header = (Elf32_Ehdr*)m_file_mapping;
+    return validate_elf_header(*elf_header, m_file_size) && validate_program_headers(*elf_header, m_file_size, (u8*)m_file_mapping, m_file_size, &m_program_interpreter);
+}
+
+DynamicLoader::~DynamicLoader()
+{
+    if (MAP_FAILED != m_file_mapping)
+        munmap(m_file_mapping, m_file_size);
+    close(m_image_fd);
+}
+
+void* DynamicLoader::symbol_for_name(const char* name)
+{
+    auto symbol = m_dynamic_object->hash_section().lookup_symbol(name);
+
+    if (symbol.is_undefined())
+        return nullptr;
+
+    return m_dynamic_object->base_address().offset(symbol.value()).as_ptr();
+}
+
+RefPtr<DynamicObject> DynamicLoader::load_from_image(unsigned flags, size_t total_tls_size)
+{
+
+    m_valid = m_elf_image.is_valid();
+
+    if (!m_valid) {
+        dbgprintf("DynamicLoader::load_from_image failed: image is invalid\n");
+        return nullptr;
+    }
+
+#ifdef DYNAMIC_LOAD_VERBOSE
+    // m_image->dump();
+#endif
+
+    load_program_headers();
+
+    m_dynamic_object = DynamicObject::construct(m_text_segment_load_address, m_dynamic_section_address);
+    m_dynamic_object->set_tls_offset(m_tls_offset);
+    m_dynamic_object->set_tls_size(m_tls_size);
+
+    auto rc = load_stage_2(flags, total_tls_size);
+    if (!rc) {
+        dbgprintf("DynamicLoader::load_from_image failed at load_stage_2\n");
+        return nullptr;
+    }
+    return m_dynamic_object;
+}
+
+bool DynamicLoader::load_stage_2(unsigned flags, size_t total_tls_size)
+{
+    ASSERT(flags & RTLD_GLOBAL);
+
+#ifdef DYNAMIC_LOAD_DEBUG
+    m_dynamic_object->dump();
+#endif
+
+    if (m_dynamic_object->has_text_relocations()) {
+        ASSERT(m_text_segment_load_address.get() != 0);
+
+#ifndef AK_OS_MACOS
+        // Remap this text region as private.
+        if (mremap(m_text_segment_load_address.as_ptr(), m_text_segment_size, m_text_segment_size, MAP_PRIVATE) == MAP_FAILED) {
+            perror("mremap .text: MAP_PRIVATE");
+            return false;
+        }
+#endif
+
+        if (0 > mprotect(m_text_segment_load_address.as_ptr(), m_text_segment_size, PROT_READ | PROT_WRITE)) {
+            perror("mprotect .text: PROT_READ | PROT_WRITE"); // FIXME: dlerror?
+            return false;
+        }
+    }
+    do_main_relocations(total_tls_size);
+    return true;
+}
+
+void DynamicLoader::do_main_relocations(size_t total_tls_size)
+{
+    auto do_single_relocation = [&](ELF::DynamicObject::Relocation relocation) {
+        switch (do_relocation(total_tls_size, relocation)) {
+        case RelocationResult::Failed:
+            dbgln("Loader.so: {} unresolved symbol '{}'", m_filename, relocation.symbol().name());
+            ASSERT_NOT_REACHED();
+            break;
+        case RelocationResult::ResolveLater:
+            m_unresolved_relocations.append(relocation);
+            break;
+        case RelocationResult::Success:
+            break;
+        }
+        return IterationDecision::Continue;
+    };
+    m_dynamic_object->relocation_section().for_each_relocation(do_single_relocation);
+    m_dynamic_object->plt_relocation_section().for_each_relocation(do_single_relocation);
+}
+
+RefPtr<DynamicObject> DynamicLoader::load_stage_3(unsigned flags, size_t total_tls_size)
+{
+
+    do_lazy_relocations(total_tls_size);
+    if (flags & RTLD_LAZY) {
+        setup_plt_trampoline();
+    }
+
+    // Clean up our setting of .text to PROT_READ | PROT_WRITE
+    if (m_dynamic_object->has_text_relocations()) {
+        if (0 > mprotect(m_text_segment_load_address.as_ptr(), m_text_segment_size, PROT_READ | PROT_EXEC)) {
+            perror("mprotect .text: PROT_READ | PROT_EXEC"); // FIXME: dlerror?
+            return nullptr;
+        }
+    }
+
+    call_object_init_functions();
+
+    VERBOSE("Loaded %s\n", m_filename.characters());
+    return m_dynamic_object;
+}
+
+void DynamicLoader::do_lazy_relocations(size_t total_tls_size)
+{
+    for (const auto& relocation : m_unresolved_relocations) {
+        if (auto res = do_relocation(total_tls_size, relocation); res != RelocationResult::Success) {
+            dbgln("Loader.so: {} unresolved symbol '{}'", m_filename, relocation.symbol().name());
+            ASSERT_NOT_REACHED();
+        }
+    }
+}
+
+void DynamicLoader::load_program_headers()
+{
+    Vector<ProgramHeaderRegion> program_headers;
+
+    ProgramHeaderRegion* text_region_ptr = nullptr;
+    ProgramHeaderRegion* data_region_ptr = nullptr;
+    ProgramHeaderRegion* tls_region_ptr = nullptr;
+    VirtualAddress dynamic_region_desired_vaddr;
+
+    m_elf_image.for_each_program_header([&](const Image::ProgramHeader& program_header) {
+        ProgramHeaderRegion new_region;
+        new_region.set_program_header(program_header.raw_header());
+        program_headers.append(move(new_region));
+        auto& region = program_headers.last();
+        if (region.is_tls_template())
+            tls_region_ptr = &region;
+        else if (region.is_load()) {
+            if (region.is_executable())
+                text_region_ptr = &region;
+            else
+                data_region_ptr = &region;
+        } else if (region.is_dynamic()) {
+            dynamic_region_desired_vaddr = region.desired_load_address();
+        }
+        return IterationDecision::Continue;
+    });
+
+    ASSERT(text_region_ptr && data_region_ptr);
+
+    // Process regions in order: .text, .data, .tls
+    auto* region = text_region_ptr;
+    void* requested_load_address = m_elf_image.is_dynamic() ? nullptr : region->desired_load_address().as_ptr();
+
+    ASSERT(!region->is_writable());
+
+    void* text_segment_begin = mmap_with_name(
+        requested_load_address,
+        region->required_load_size(),
+        region->mmap_prot(),
+        MAP_SHARED,
+        m_image_fd,
+        region->offset(),
+        String::format("%s: .text", m_filename.characters()).characters());
+    if (MAP_FAILED == text_segment_begin) {
+        ASSERT_NOT_REACHED();
+    }
+    ASSERT(requested_load_address == nullptr || requested_load_address == text_segment_begin);
+    m_text_segment_size = region->required_load_size();
+    m_text_segment_load_address = VirtualAddress { (FlatPtr)text_segment_begin };
+
+    if (m_elf_image.is_dynamic())
+        m_dynamic_section_address = dynamic_region_desired_vaddr.offset(m_text_segment_load_address.get());
+    else
+        m_dynamic_section_address = dynamic_region_desired_vaddr;
+
+    region = data_region_ptr;
+    void* data_segment_begin = mmap_with_name(
+        (u8*)text_segment_begin + m_text_segment_size,
+        region->required_load_size(),
+        region->mmap_prot(),
+        MAP_ANONYMOUS | MAP_PRIVATE,
+        0,
+        0,
+        String::format("%s: .data", m_filename.characters()).characters());
+    if (MAP_FAILED == data_segment_begin) {
+        ASSERT_NOT_REACHED();
+    }
+    VirtualAddress data_segment_actual_addr;
+    if (m_elf_image.is_dynamic()) {
+        data_segment_actual_addr = region->desired_load_address().offset((FlatPtr)text_segment_begin);
+    } else {
+        data_segment_actual_addr = region->desired_load_address();
+    }
+    memcpy(data_segment_actual_addr.as_ptr(), (u8*)m_file_mapping + region->offset(), region->size_in_image());
+    // FIXME: Initialize the values in the TLS section. Currently, it is zeroed.
+}
+
+DynamicLoader::RelocationResult DynamicLoader::do_relocation(size_t total_tls_size, ELF::DynamicObject::Relocation relocation)
+{
+    VERBOSE("Relocation symbol: %s, type: %d\n", relocation.symbol().name(), relocation.type());
+    FlatPtr* patch_ptr = nullptr;
+    if (is_dynamic())
+        patch_ptr = (FlatPtr*)(m_dynamic_object->base_address().as_ptr() + relocation.offset());
+    else
+        patch_ptr = (FlatPtr*)(FlatPtr)relocation.offset();
+
+    // VERBOSE("dynamic object name: %s\n", dynamic_object.object_name());
+    VERBOSE("dynamic object base address: %p\n", m_dynamic_object->base_address());
+    VERBOSE("relocation offset: 0x%x\n", relocation.offset());
+    VERBOSE("patch_ptr: %p\n", patch_ptr);
+    switch (relocation.type()) {
+    case R_386_NONE:
+        // Apparently most loaders will just skip these?
+        // Seems if the 'link editor' generates one something is funky with your code
+        VERBOSE("None relocation. No symbol, no nothing.\n");
+        break;
+    case R_386_32: {
+        auto symbol = relocation.symbol();
+        VERBOSE("Absolute relocation: name: '%s', value: %p\n", symbol.name(), symbol.value());
+        auto res = lookup_symbol(symbol);
+        if (!res.found) {
+            if (symbol.bind() == STB_WEAK) {
+                return RelocationResult::ResolveLater;
+            }
+            dbgln("ERROR: symbol not found: {}.", symbol.name());
+            ASSERT_NOT_REACHED();
+        }
+        u32 symbol_address = res.address;
+        *patch_ptr += symbol_address;
+        VERBOSE("   Symbol address: %p\n", *patch_ptr);
+        break;
+    }
+    case R_386_PC32: {
+        auto symbol = relocation.symbol();
+        VERBOSE("PC-relative relocation: '%s', value: %p\n", symbol.name(), symbol.value());
+        auto res = lookup_symbol(symbol);
+        ASSERT(res.found);
+        u32 relative_offset = (res.address - (FlatPtr)(m_dynamic_object->base_address().as_ptr() + relocation.offset()));
+        *patch_ptr += relative_offset;
+        VERBOSE("   Symbol address: %p\n", *patch_ptr);
+        break;
+    }
+    case R_386_GLOB_DAT: {
+        auto symbol = relocation.symbol();
+        VERBOSE("Global data relocation: '%s', value: %p\n", symbol.name(), symbol.value());
+        auto res = lookup_symbol(symbol);
+        if (!res.found) {
+            // We do not support these
+            // TODO: Can we tell gcc not to generate the piece of code that uses these?
+            // (--disable-tm-clone-registry flag in gcc conifugraion?)
+            if (!strcmp(symbol.name(), "__deregister_frame_info") || !strcmp(symbol.name(), "_ITM_registerTMCloneTable")
+                || !strcmp(symbol.name(), "_ITM_deregisterTMCloneTable") || !strcmp(symbol.name(), "__register_frame_info")) {
+                break;
+            }
+
+            if (symbol.bind() == STB_WEAK) {
+                return RelocationResult::ResolveLater;
+            }
+
+            // Symbol not found
+            return RelocationResult::Failed;
+        }
+        VERBOSE("was symbol found? %d, address: 0x%x\n", res.found, res.address);
+        VERBOSE("object: %s\n", m_filename.characters());
+
+        u32 symbol_location = res.address;
+        ASSERT(symbol_location != (FlatPtr)m_dynamic_object->base_address().as_ptr());
+        *patch_ptr = symbol_location;
+        VERBOSE("   Symbol address: %p\n", *patch_ptr);
+        break;
+    }
+    case R_386_RELATIVE: {
+        // FIXME: According to the spec, R_386_relative ones must be done first.
+        //     We could explicitly do them first using m_number_of_relocatoins from DT_RELCOUNT
+        //     However, our compiler is nice enough to put them at the front of the relocations for us :)
+        VERBOSE("Load address relocation at offset %X\n", relocation.offset());
+        VERBOSE("    patch ptr == %p, adding load base address (%p) to it and storing %p\n", *patch_ptr, m_dynamic_object->base_address().as_ptr(), *patch_ptr + m_dynamic_object->base_address().as_ptr());
+        *patch_ptr += (FlatPtr)m_dynamic_object->base_address().as_ptr(); // + addend for RelA (addend for Rel is stored at addr)
+        break;
+    }
+    case R_386_TLS_TPOFF32:
+    case R_386_TLS_TPOFF: {
+        VERBOSE("Relocation type: R_386_TLS_TPOFF at offset %X\n", relocation.offset());
+        auto symbol = relocation.symbol();
+        // For some reason, LibC has a R_386_TLS_TPOFF that refers to the undefined symbol.. huh
+        if (relocation.symbol_index() == 0)
+            break;
+        VERBOSE("Symbol index: %d\n", symbol.index());
+        VERBOSE("Symbol is_undefined?: %d\n", symbol.is_undefined());
+        VERBOSE("TLS relocation: '%s', value: %p\n", symbol.name(), symbol.value());
+        auto res = lookup_symbol(symbol);
+        if (!res.found)
+            break;
+        ASSERT(res.found);
+        u32 symbol_value = res.value;
+        VERBOSE("symbol value: %d\n", symbol_value);
+        const auto dynamic_object_of_symbol = res.dynamic_object;
+        ASSERT(dynamic_object_of_symbol);
+        size_t offset_of_tls_end = dynamic_object_of_symbol->tls_offset().value() + dynamic_object_of_symbol->tls_size().value();
+        // size_t offset_of_tls_end = tls_offset() + tls_size();
+        VERBOSE("patch ptr: 0x%x\n", patch_ptr);
+        VERBOSE("tls end offset: %d, total tls size: %d\n", offset_of_tls_end, total_tls_size);
+        *patch_ptr = (offset_of_tls_end - total_tls_size - symbol_value - sizeof(Elf32_Addr));
+        VERBOSE("*patch ptr: %d\n", (i32)*patch_ptr);
+        break;
+    }
+    case R_386_JMP_SLOT: {
+        // FIXME: Or BIND_NOW flag passed in?
+        if (m_dynamic_object->must_bind_now() || s_always_bind_now) {
+            // Eagerly BIND_NOW the PLT entries, doing all the symbol looking goodness
+            // The patch method returns the address for the LAZY fixup path, but we don't need it here
+            VERBOSE("patching plt reloaction: 0x%x\n", relocation.offset_in_section());
+            [[maybe_unused]] auto rc = m_dynamic_object->patch_plt_entry(relocation.offset_in_section());
+        } else {
+            u8* relocation_address = relocation.address().as_ptr();
+
+            if (m_elf_image.is_dynamic())
+                *(u32*)relocation_address += (FlatPtr)m_dynamic_object->base_address().as_ptr();
+        }
+        break;
+    }
+    default:
+        // Raise the alarm! Someone needs to implement this relocation type
+        VERBOSE("Found a new exciting relocation type %d\n", relocation.type());
+        // printf("DynamicLoader: Found unknown relocation type %d\n", relocation.type());
+        ASSERT_NOT_REACHED();
+        break;
+    }
+    return RelocationResult::Success;
+}
+
+// Defined in <arch>/plt_trampoline.S
+extern "C" void _plt_trampoline(void) __attribute__((visibility("hidden")));
+
+void DynamicLoader::setup_plt_trampoline()
+{
+    ASSERT(m_dynamic_object);
+    VirtualAddress got_address = m_dynamic_object->plt_got_base_address();
+
+    FlatPtr* got_ptr = (FlatPtr*)got_address.as_ptr();
+    got_ptr[1] = (FlatPtr)m_dynamic_object.ptr();
+    got_ptr[2] = (FlatPtr)&_plt_trampoline;
+
+    VERBOSE("Set GOT PLT entries at %p: [0] = %p [1] = %p, [2] = %p\n", got_ptr, (void*)got_ptr[0], (void*)got_ptr[1], (void*)got_ptr[2]);
+}
+
+// Called from our ASM routine _plt_trampoline.
+// Tell the compiler that it might be called from other places:
+extern "C" Elf32_Addr _fixup_plt_entry(DynamicObject* object, u32 relocation_offset);
+extern "C" Elf32_Addr _fixup_plt_entry(DynamicObject* object, u32 relocation_offset)
+{
+    return object->patch_plt_entry(relocation_offset);
+}
+
+void DynamicLoader::call_object_init_functions()
+{
+    typedef void (*InitFunc)();
+
+    if (m_dynamic_object->has_init_section()) {
+        auto init_function = (InitFunc)(m_dynamic_object->init_section().address().as_ptr());
+
+        VERBOSE("Calling DT_INIT at %p\n", init_function);
+        (init_function)();
+    }
+
+    if (m_dynamic_object->has_init_array_section()) {
+        auto init_array_section = m_dynamic_object->init_array_section();
+
+        InitFunc* init_begin = (InitFunc*)(init_array_section.address().as_ptr());
+        InitFunc* init_end = init_begin + init_array_section.entry_count();
+        while (init_begin != init_end) {
+            // Android sources claim that these can be -1, to be ignored.
+            // 0 definitely shows up. Apparently 0/-1 are valid? Confusing.
+            if (!*init_begin || ((FlatPtr)*init_begin == (FlatPtr)-1))
+                continue;
+            VERBOSE("Calling DT_INITARRAY entry at %p\n", *init_begin);
+            (*init_begin)();
+            ++init_begin;
+        }
+    }
+}
+
+u32 DynamicLoader::ProgramHeaderRegion::mmap_prot() const
+{
+    int prot = 0;
+    prot |= is_executable() ? PROT_EXEC : 0;
+    prot |= is_readable() ? PROT_READ : 0;
+    prot |= is_writable() ? PROT_WRITE : 0;
+    return prot;
+}
+
+DynamicObject::SymbolLookupResult DynamicLoader::lookup_symbol(const ELF::DynamicObject::Symbol& symbol) const
+{
+    return m_dynamic_object->lookup_symbol(symbol);
+}
+
+} // end namespace ELF

Userland/Libraries/LibELF/DynamicLoader.h

@@ -0,0 +1,164 @@
+/*
+ * Copyright (c) 2019-2020, Andrew Kaster <andrewdkaster@gmail.com>
+ * Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/Assertions.h>
+#include <AK/OwnPtr.h>
+#include <AK/RefCounted.h>
+#include <AK/String.h>
+#include <LibELF/DynamicObject.h>
+#include <LibELF/Image.h>
+#include <LibELF/exec_elf.h>
+#include <sys/mman.h>
+
+namespace ELF {
+
+#define ALIGN_ROUND_UP(x, align) ((((size_t)(x)) + align - 1) & (~(align - 1)))
+
+class DynamicLoader : public RefCounted<DynamicLoader> {
+public:
+    static NonnullRefPtr<DynamicLoader> construct(const char* filename, int fd, size_t file_size);
+
+    ~DynamicLoader();
+
+    bool is_valid() const { return m_valid; }
+
+    // Load a full ELF image from file into the current process and create an DynamicObject
+    // from the SHT_DYNAMIC in the file.
+    RefPtr<DynamicObject> load_from_image(unsigned flags, size_t total_tls_size);
+
+    // Stage 2 of loading: dynamic object loading and primary relocations
+    bool load_stage_2(unsigned flags, size_t total_tls_size);
+
+    // Stage 3 of loading: lazy relocations and initializers
+    RefPtr<DynamicObject> load_stage_3(unsigned flags, size_t total_tls_size);
+    // Intended for use by dlsym or other internal methods
+    void* symbol_for_name(const char*);
+
+    void dump();
+
+    // Requested program interpreter from program headers. May be empty string
+    StringView program_interpreter() const { return m_program_interpreter; }
+
+    VirtualAddress text_segment_load_addresss() const { return m_text_segment_load_address; }
+
+    void set_tls_offset(size_t offset) { m_tls_offset = offset; };
+    size_t tls_size() const { return m_tls_size; }
+    size_t tls_offset() const { return m_tls_offset; }
+    const ELF::Image& image() const { return m_elf_image; }
+
+    template<typename F>
+    void for_each_needed_library(F) const;
+
+    VirtualAddress text_segment_load_address() const { return m_text_segment_load_address; }
+    bool is_dynamic() const { return m_elf_image.is_dynamic(); }
+
+private:
+    class ProgramHeaderRegion {
+    public:
+        void set_program_header(const Elf32_Phdr& header) { m_program_header = header; }
+
+        // Information from ELF Program header
+        u32 type() const { return m_program_header.p_type; }
+        u32 flags() const { return m_program_header.p_flags; }
+        u32 offset() const { return m_program_header.p_offset; }
+        VirtualAddress desired_load_address() const { return VirtualAddress(m_program_header.p_vaddr); }
+        u32 size_in_memory() const { return m_program_header.p_memsz; }
+        u32 size_in_image() const { return m_program_header.p_filesz; }
+        u32 alignment() const { return m_program_header.p_align; }
+        u32 mmap_prot() const;
+        bool is_readable() const { return flags() & PF_R; }
+        bool is_writable() const { return flags() & PF_W; }
+        bool is_executable() const { return flags() & PF_X; }
+        bool is_tls_template() const { return type() == PT_TLS; }
+        bool is_load() const { return type() == PT_LOAD; }
+        bool is_dynamic() const { return type() == PT_DYNAMIC; }
+
+        u32 required_load_size() { return ALIGN_ROUND_UP(m_program_header.p_memsz, m_program_header.p_align); }
+
+    private:
+        Elf32_Phdr m_program_header; // Explicitly a copy of the PHDR in the image
+    };
+
+    static void* do_mmap(int fd, size_t size, const String& name);
+    RefPtr<DynamicObject> dynamic_object_from_image() const;
+
+    explicit DynamicLoader(const char* filename, int fd, size_t file_size);
+
+    // Stage 1
+    void load_program_headers();
+
+    // Stage 2
+    void do_main_relocations(size_t total_tls_size);
+
+    // Stage 3
+    void do_lazy_relocations(size_t total_tls_size);
+    void setup_plt_trampoline();
+    void call_object_init_functions();
+
+    bool validate();
+
+    enum class RelocationResult : uint8_t {
+        Failed = 0,
+        Success = 1,
+        ResolveLater = 2,
+    };
+    RelocationResult do_relocation(size_t total_tls_size, DynamicObject::Relocation relocation);
+    size_t calculate_tls_size() const;
+
+    DynamicObject::SymbolLookupResult lookup_symbol(const ELF::DynamicObject::Symbol& symbol) const;
+
+    String m_filename;
+    String m_program_interpreter;
+    size_t m_file_size { 0 };
+    int m_image_fd { -1 };
+    void* m_file_mapping { MAP_FAILED };
+    ELF::Image m_elf_image;
+    bool m_valid { true };
+
+    RefPtr<DynamicObject> m_dynamic_object;
+
+    VirtualAddress m_text_segment_load_address;
+    size_t m_text_segment_size { 0 };
+
+    VirtualAddress m_tls_segment_address;
+    VirtualAddress m_dynamic_section_address;
+
+    size_t m_tls_offset { 0 };
+    size_t m_tls_size { 0 };
+
+    Vector<DynamicObject::Relocation> m_unresolved_relocations;
+};
+
+template<typename F>
+void DynamicLoader::for_each_needed_library(F func) const
+{
+    dynamic_object_from_image()->for_each_needed_library(move(func));
+}
+
+} // end namespace ELF

Userland/Libraries/LibELF/DynamicObject.cpp

@@ -0,0 +1,527 @@
+/*
+ * Copyright (c) 2019-2020, Andrew Kaster <andrewdkaster@gmail.com>
+ * Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <AK/String.h>
+#include <AK/StringBuilder.h>
+#include <LibELF/DynamicLinker.h>
+#include <LibELF/DynamicObject.h>
+#include <LibELF/exec_elf.h>
+#include <stdio.h>
+#include <string.h>
+
+// #define DYNAMIC_OBJECT_VERBOSE
+
+#ifdef DYNAMIC_OBJECT_VERBOSE
+#    define VERBOSE(fmt, ...) dbgprintf(fmt, ##__VA_ARGS__)
+#else
+#    define VERBOSE(fmt, ...) \
+        do {                  \
+        } while (0)
+#endif
+
+namespace ELF {
+
+static const char* name_for_dtag(Elf32_Sword d_tag);
+
+DynamicObject::DynamicObject(VirtualAddress base_address, VirtualAddress dynamic_section_addresss)
+    : m_base_address(base_address)
+    , m_dynamic_address(dynamic_section_addresss)
+{
+    Elf32_Ehdr* header = (Elf32_Ehdr*)base_address.as_ptr();
+    Elf32_Phdr* pheader = (Elf32_Phdr*)(base_address.as_ptr() + header->e_phoff);
+    m_elf_base_address = VirtualAddress(pheader->p_vaddr - pheader->p_offset);
+    if (header->e_type == ET_DYN)
+        m_is_elf_dynamic = true;
+    else
+        m_is_elf_dynamic = false;
+
+    parse();
+}
+
+DynamicObject::~DynamicObject()
+{
+}
+
+void DynamicObject::dump() const
+{
+    StringBuilder builder;
+    builder.append("\nd_tag      tag_name         value\n");
+    size_t num_dynamic_sections = 0;
+
+    for_each_dynamic_entry([&](const DynamicObject::DynamicEntry& entry) {
+        String name_field = String::format("(%s)", name_for_dtag(entry.tag()));
+        builder.appendf("0x%08X %-17s0x%X\n", entry.tag(), name_field.characters(), entry.val());
+        num_dynamic_sections++;
+        return IterationDecision::Continue;
+    });
+
+    if (m_has_soname)
+        builder.appendf("DT_SONAME: %s\n", soname()); // FIXME: Valdidate that this string is null terminated?
+
+    VERBOSE("Dynamic section at address %p contains %zu entries:\n", m_dynamic_address.as_ptr(), num_dynamic_sections);
+    VERBOSE("%s", builder.to_string().characters());
+}
+
+void DynamicObject::parse()
+{
+    for_each_dynamic_entry([&](const DynamicEntry& entry) {
+        switch (entry.tag()) {
+        case DT_INIT:
+            m_init_offset = entry.ptr() - (FlatPtr)m_elf_base_address.as_ptr();
+            break;
+        case DT_FINI:
+            m_fini_offset = entry.ptr() - (FlatPtr)m_elf_base_address.as_ptr();
+            break;
+        case DT_INIT_ARRAY:
+            m_init_array_offset = entry.ptr() - (FlatPtr)m_elf_base_address.as_ptr();
+            break;
+        case DT_INIT_ARRAYSZ:
+            m_init_array_size = entry.val();
+            break;
+        case DT_FINI_ARRAY:
+            m_fini_array_offset = entry.ptr() - (FlatPtr)m_elf_base_address.as_ptr();
+            break;
+        case DT_FINI_ARRAYSZ:
+            m_fini_array_size = entry.val();
+            break;
+        case DT_HASH:
+            // Use SYSV hash only if GNU hash is not available
+            if (m_hash_type == HashType::SYSV) {
+                m_hash_table_offset = entry.ptr() - (FlatPtr)m_elf_base_address.as_ptr();
+            }
+            break;
+        case DT_GNU_HASH:
+            m_hash_type = HashType::GNU;
+            m_hash_table_offset = entry.ptr() - (FlatPtr)m_elf_base_address.as_ptr();
+            break;
+        case DT_SYMTAB:
+            m_symbol_table_offset = entry.ptr() - (FlatPtr)m_elf_base_address.as_ptr();
+            break;
+        case DT_STRTAB:
+            m_string_table_offset = entry.ptr() - (FlatPtr)m_elf_base_address.as_ptr();
+            break;
+        case DT_STRSZ:
+            m_size_of_string_table = entry.val();
+            break;
+        case DT_SYMENT:
+            m_size_of_symbol_table_entry = entry.val();
+            break;
+        case DT_PLTGOT:
+            m_procedure_linkage_table_offset = entry.ptr() - (FlatPtr)m_elf_base_address.as_ptr();
+            break;
+        case DT_PLTRELSZ:
+            m_size_of_plt_relocation_entry_list = entry.val();
+            break;
+        case DT_PLTREL:
+            m_procedure_linkage_table_relocation_type = entry.val();
+            ASSERT(m_procedure_linkage_table_relocation_type & (DT_REL | DT_RELA));
+            break;
+        case DT_JMPREL:
+            m_plt_relocation_offset_location = entry.ptr() - (FlatPtr)m_elf_base_address.as_ptr();
+            break;
+        case DT_RELA:
+        case DT_REL:
+            m_relocation_table_offset = entry.ptr() - (FlatPtr)m_elf_base_address.as_ptr();
+            break;
+        case DT_RELASZ:
+        case DT_RELSZ:
+            m_size_of_relocation_table = entry.val();
+            break;
+        case DT_RELAENT:
+        case DT_RELENT:
+            m_size_of_relocation_entry = entry.val();
+            break;
+        case DT_RELACOUNT:
+        case DT_RELCOUNT:
+            m_number_of_relocations = entry.val();
+            break;
+        case DT_FLAGS:
+            m_dt_flags = entry.val();
+            break;
+        case DT_TEXTREL:
+            m_dt_flags |= DF_TEXTREL; // This tag seems to exist for legacy reasons only?
+            break;
+        case DT_SONAME:
+            m_soname_index = entry.val();
+            m_has_soname = true;
+            break;
+        case DT_DEBUG:
+            break;
+        case DT_FLAGS_1:
+            break;
+        case DT_NEEDED:
+            // We handle these in for_each_needed_library
+            break;
+        default:
+            dbgprintf("DynamicObject: DYNAMIC tag handling not implemented for DT_%s\n", name_for_dtag(entry.tag()));
+            printf("DynamicObject: DYNAMIC tag handling not implemented for DT_%s\n", name_for_dtag(entry.tag()));
+            ASSERT_NOT_REACHED(); // FIXME: Maybe just break out here and return false?
+            break;
+        }
+        return IterationDecision::Continue;
+    });
+
+    if (!m_size_of_relocation_entry) {
+        // TODO: FIXME, this shouldn't be hardcoded
+        // The reason we need this here is that for some reason, when there only PLT relocations, the compiler
+        // doesn't insert a 'PLTRELSZ' entry to the dynamic section
+        m_size_of_relocation_entry = sizeof(Elf32_Rel);
+    }
+
+    auto hash_section_address = hash_section().address().as_ptr();
+    // TODO: consider base address - it might not be zero
+    auto num_hash_chains = ((u32*)hash_section_address)[1];
+    m_symbol_count = num_hash_chains;
+}
+
+const DynamicObject::Relocation DynamicObject::RelocationSection::relocation(unsigned index) const
+{
+    ASSERT(index < entry_count());
+    unsigned offset_in_section = index * entry_size();
+    auto relocation_address = (Elf32_Rel*)address().offset(offset_in_section).as_ptr();
+    return Relocation(m_dynamic, *relocation_address, offset_in_section);
+}
+
+const DynamicObject::Relocation DynamicObject::RelocationSection::relocation_at_offset(unsigned offset) const
+{
+    ASSERT(offset <= (m_section_size_bytes - m_entry_size));
+    auto relocation_address = (Elf32_Rel*)address().offset(offset).as_ptr();
+    return Relocation(m_dynamic, *relocation_address, offset);
+}
+
+const DynamicObject::Symbol DynamicObject::symbol(unsigned index) const
+{
+    auto symbol_section = Section(*this, m_symbol_table_offset, (m_symbol_count * m_size_of_symbol_table_entry), m_size_of_symbol_table_entry, "DT_SYMTAB");
+    auto symbol_entry = (Elf32_Sym*)symbol_section.address().offset(index * symbol_section.entry_size()).as_ptr();
+    return Symbol(*this, index, *symbol_entry);
+}
+
+const DynamicObject::Section DynamicObject::init_section() const
+{
+    return Section(*this, m_init_offset, sizeof(void (*)()), sizeof(void (*)()), "DT_INIT");
+}
+
+const DynamicObject::Section DynamicObject::fini_section() const
+{
+    return Section(*this, m_fini_offset, sizeof(void (*)()), sizeof(void (*)()), "DT_FINI");
+}
+
+const DynamicObject::Section DynamicObject::init_array_section() const
+{
+    return Section(*this, m_init_array_offset, m_init_array_size, sizeof(void (*)()), "DT_INIT_ARRAY");
+}
+
+const DynamicObject::Section DynamicObject::fini_array_section() const
+{
+    return Section(*this, m_fini_array_offset, m_fini_array_size, sizeof(void (*)()), "DT_FINI_ARRAY");
+}
+
+const DynamicObject::HashSection DynamicObject::hash_section() const
+{
+    const char* section_name = m_hash_type == HashType::SYSV ? "DT_HASH" : "DT_GNU_HASH";
+    return HashSection(Section(*this, m_hash_table_offset, 0, 0, section_name), m_hash_type);
+}
+
+const DynamicObject::RelocationSection DynamicObject::relocation_section() const
+{
+    return RelocationSection(Section(*this, m_relocation_table_offset, m_size_of_relocation_table, m_size_of_relocation_entry, "DT_REL"));
+}
+
+const DynamicObject::RelocationSection DynamicObject::plt_relocation_section() const
+{
+    return RelocationSection(Section(*this, m_plt_relocation_offset_location, m_size_of_plt_relocation_entry_list, m_size_of_relocation_entry, "DT_JMPREL"));
+}
+
+u32 DynamicObject::HashSection::calculate_elf_hash(const char* name) const
+{
+    // SYSV ELF hash algorithm
+    // Note that the GNU HASH algorithm has less collisions
+
+    uint32_t hash = 0;
+
+    while (*name != '\0') {
+        hash = hash << 4;
+        hash += *name;
+        name++;
+
+        const uint32_t top_nibble_of_hash = hash & 0xF0000000U;
+        hash ^= top_nibble_of_hash >> 24;
+        hash &= ~top_nibble_of_hash;
+    }
+
+    return hash;
+}
+
+u32 DynamicObject::HashSection::calculate_gnu_hash(const char* name) const
+{
+    // GNU ELF hash algorithm
+    u32 hash = 5381;
+
+    for (; *name != '\0'; ++name) {
+        hash = hash * 33 + *name;
+    }
+
+    return hash;
+}
+
+const DynamicObject::Symbol DynamicObject::HashSection::lookup_symbol(const char* name) const
+{
+    return (this->*(m_lookup_function))(name);
+}
+
+const DynamicObject::Symbol DynamicObject::HashSection::lookup_elf_symbol(const char* name) const
+{
+    u32 hash_value = calculate_elf_hash(name);
+
+    u32* hash_table_begin = (u32*)address().as_ptr();
+
+    size_t num_buckets = hash_table_begin[0];
+
+    // This is here for completeness, but, since we're using the fact that every chain
+    // will end at chain 0 (which means 'not found'), we don't need to check num_chains.
+    // Interestingly, num_chains is required to be num_symbols
+
+    // size_t num_chains = hash_table_begin[1];
+
+    u32* buckets = &hash_table_begin[2];
+    u32* chains = &buckets[num_buckets];
+
+    for (u32 i = buckets[hash_value % num_buckets]; i; i = chains[i]) {
+        auto symbol = m_dynamic.symbol(i);
+        if (strcmp(name, symbol.name()) == 0) {
+            VERBOSE("Returning SYSV dynamic symbol with index %u for %s: %p\n", i, symbol.name(), symbol.address().as_ptr());
+            return symbol;
+        }
+    }
+    return Symbol::create_undefined(m_dynamic);
+}
+
+const DynamicObject::Symbol DynamicObject::HashSection::lookup_gnu_symbol(const char* name) const
+{
+    // Algorithm reference: https://ent-voy.blogspot.com/2011/02/
+    // TODO: Handle 64bit bloomwords for ELF_CLASS64
+    using BloomWord = u32;
+    constexpr size_t bloom_word_size = sizeof(BloomWord) * 8;
+
+    const u32* hash_table_begin = (u32*)address().as_ptr();
+
+    const size_t num_buckets = hash_table_begin[0];
+    const size_t num_omitted_symbols = hash_table_begin[1];
+    const u32 num_maskwords = hash_table_begin[2];
+    // This works because num_maskwords is required to be a power of 2
+    const u32 num_maskwords_bitmask = num_maskwords - 1;
+    const u32 shift2 = hash_table_begin[3];
+
+    const BloomWord* bloom_words = &hash_table_begin[4];
+    const u32* const buckets = &bloom_words[num_maskwords];
+    const u32* const chains = &buckets[num_buckets];
+
+    BloomWord hash1 = calculate_gnu_hash(name);
+    BloomWord hash2 = hash1 >> shift2;
+    const BloomWord bitmask = (1 << (hash1 % bloom_word_size)) | (1 << (hash2 % bloom_word_size));
+
+    if ((bloom_words[(hash1 / bloom_word_size) & num_maskwords_bitmask] & bitmask) != bitmask) {
+        return Symbol::create_undefined(m_dynamic);
+    }
+
+    size_t current_sym = buckets[hash1 % num_buckets];
+    if (current_sym == 0) {
+        return Symbol::create_undefined(m_dynamic);
+    }
+    const u32* current_chain = &chains[current_sym - num_omitted_symbols];
+
+    for (hash1 &= ~1;; ++current_sym) {
+        hash2 = *(current_chain++);
+        const auto symbol = m_dynamic.symbol(current_sym);
+        if ((hash1 == (hash2 & ~1)) && strcmp(name, symbol.name()) == 0) {
+            VERBOSE("Returning GNU dynamic symbol with index %zu for %s: %p\n", current_sym, symbol.name(), symbol.address().as_ptr());
+            return symbol;
+        }
+        if (hash2 & 1) {
+            break;
+        }
+    }
+
+    return Symbol::create_undefined(m_dynamic);
+}
+
+const char* DynamicObject::symbol_string_table_string(Elf32_Word index) const
+{
+    return (const char*)base_address().offset(m_string_table_offset + index).as_ptr();
+}
+
+DynamicObject::InitializationFunction DynamicObject::init_section_function() const
+{
+    ASSERT(has_init_section());
+    return (InitializationFunction)init_section().address().as_ptr();
+}
+
+static const char* name_for_dtag(Elf32_Sword d_tag)
+{
+    switch (d_tag) {
+    case DT_NULL:
+        return "NULL"; /* marks end of _DYNAMIC array */
+    case DT_NEEDED:
+        return "NEEDED"; /* string table offset of needed lib */
+    case DT_PLTRELSZ:
+        return "PLTRELSZ"; /* size of relocation entries in PLT */
+    case DT_PLTGOT:
+        return "PLTGOT"; /* address PLT/GOT */
+    case DT_HASH:
+        return "HASH"; /* address of symbol hash table */
+    case DT_STRTAB:
+        return "STRTAB"; /* address of string table */
+    case DT_SYMTAB:
+        return "SYMTAB"; /* address of symbol table */
+    case DT_RELA:
+        return "RELA"; /* address of relocation table */
+    case DT_RELASZ:
+        return "RELASZ"; /* size of relocation table */
+    case DT_RELAENT:
+        return "RELAENT"; /* size of relocation entry */
+    case DT_STRSZ:
+        return "STRSZ"; /* size of string table */
+    case DT_SYMENT:
+        return "SYMENT"; /* size of symbol table entry */
+    case DT_INIT:
+        return "INIT"; /* address of initialization func. */
+    case DT_FINI:
+        return "FINI"; /* address of termination function */
+    case DT_SONAME:
+        return "SONAME"; /* string table offset of shared obj */
+    case DT_RPATH:
+        return "RPATH"; /* string table offset of library search path */
+    case DT_SYMBOLIC:
+        return "SYMBOLIC"; /* start sym search in shared obj. */
+    case DT_REL:
+        return "REL"; /* address of rel. tbl. w addends */
+    case DT_RELSZ:
+        return "RELSZ"; /* size of DT_REL relocation table */
+    case DT_RELENT:
+        return "RELENT"; /* size of DT_REL relocation entry */
+    case DT_PLTREL:
+        return "PLTREL"; /* PLT referenced relocation entry */
+    case DT_DEBUG:
+        return "DEBUG"; /* bugger */
+    case DT_TEXTREL:
+        return "TEXTREL"; /* Allow rel. mod. to unwritable seg */
+    case DT_JMPREL:
+        return "JMPREL"; /* add. of PLT's relocation entries */
+    case DT_BIND_NOW:
+        return "BIND_NOW"; /* Bind now regardless of env setting */
+    case DT_INIT_ARRAY:
+        return "INIT_ARRAY"; /* address of array of init func */
+    case DT_FINI_ARRAY:
+        return "FINI_ARRAY"; /* address of array of term func */
+    case DT_INIT_ARRAYSZ:
+        return "INIT_ARRAYSZ"; /* size of array of init func */
+    case DT_FINI_ARRAYSZ:
+        return "FINI_ARRAYSZ"; /* size of array of term func */
+    case DT_RUNPATH:
+        return "RUNPATH"; /* strtab offset of lib search path */
+    case DT_FLAGS:
+        return "FLAGS"; /* Set of DF_* flags */
+    case DT_ENCODING:
+        return "ENCODING"; /* further DT_* follow encoding rules */
+    case DT_PREINIT_ARRAY:
+        return "PREINIT_ARRAY"; /* address of array of preinit func */
+    case DT_PREINIT_ARRAYSZ:
+        return "PREINIT_ARRAYSZ"; /* size of array of preinit func */
+    case DT_LOOS:
+        return "LOOS"; /* reserved range for OS */
+    case DT_HIOS:
+        return "HIOS"; /*  specific dynamic array tags */
+    case DT_LOPROC:
+        return "LOPROC"; /* reserved range for processor */
+    case DT_HIPROC:
+        return "HIPROC"; /*  specific dynamic array tags */
+    case DT_GNU_HASH:
+        return "GNU_HASH"; /* address of GNU hash table */
+    case DT_RELACOUNT:
+        return "RELACOUNT"; /* if present, number of RELATIVE */
+    case DT_RELCOUNT:
+        return "RELCOUNT"; /* relocs, which must come first */
+    case DT_FLAGS_1:
+        return "FLAGS_1";
+    default:
+        return "??";
+    }
+}
+
+DynamicObject::SymbolLookupResult DynamicObject::lookup_symbol(const char* name) const
+{
+    auto res = hash_section().lookup_symbol(name);
+    if (res.is_undefined())
+        return {};
+    return SymbolLookupResult { true, res.value(), (FlatPtr)res.address().as_ptr(), res.bind(), this };
+}
+
+NonnullRefPtr<DynamicObject> DynamicObject::construct(VirtualAddress base_address, VirtualAddress dynamic_section_address)
+{
+    return adopt(*new DynamicObject(base_address, dynamic_section_address));
+}
+
+// offset is in PLT relocation table
+Elf32_Addr DynamicObject::patch_plt_entry(u32 relocation_offset)
+{
+    auto relocation = plt_relocation_section().relocation_at_offset(relocation_offset);
+
+    ASSERT(relocation.type() == R_386_JMP_SLOT);
+
+    auto sym = relocation.symbol();
+
+    u8* relocation_address = relocation.address().as_ptr();
+    auto res = lookup_symbol(sym);
+
+    if (!res.found) {
+        dbgln("did not find symbol: {} ", sym.name());
+        ASSERT_NOT_REACHED();
+    }
+
+    u32 symbol_location = res.address;
+
+    VERBOSE("DynamicLoader: Jump slot relocation: putting %s (%p) into PLT at %p\n", sym.name(), (void*)symbol_location, (void*)relocation_address);
+
+    *(u32*)relocation_address = symbol_location;
+
+    return symbol_location;
+}
+
+DynamicObject::SymbolLookupResult DynamicObject::lookup_symbol(const ELF::DynamicObject::Symbol& symbol) const
+{
+    VERBOSE("looking up symbol: %s\n", symbol.name());
+    if (symbol.is_undefined() || symbol.bind() == STB_WEAK)
+        return DynamicLinker::lookup_global_symbol(symbol.name());
+
+    if (!symbol.is_undefined()) {
+        VERBOSE("symbol is defined in its object\n");
+        return { true, symbol.value(), (FlatPtr)symbol.address().as_ptr(), symbol.bind(), &symbol.object() };
+    }
+    return DynamicLinker::lookup_global_symbol(symbol.name());
+}
+
+} // end namespace ELF

Userland/Libraries/LibELF/DynamicObject.h

@@ -0,0 +1,414 @@
+/*
+ * Copyright (c) 2019-2020, Andrew Kaster <andrewdkaster@gmail.com>
+ * Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/Assertions.h>
+#include <AK/RefCounted.h>
+#include <Kernel/VirtualAddress.h>
+#include <LibELF/exec_elf.h>
+
+namespace ELF {
+
+class DynamicObject : public RefCounted<DynamicObject> {
+public:
+    static NonnullRefPtr<DynamicObject> construct(VirtualAddress base_address, VirtualAddress dynamic_section_address);
+
+    ~DynamicObject();
+    void dump() const;
+
+    class DynamicEntry;
+    class Section;
+    class RelocationSection;
+    class Symbol;
+    class Relocation;
+    class HashSection;
+
+    class DynamicEntry {
+    public:
+        DynamicEntry(const Elf32_Dyn& dyn)
+            : m_dyn(dyn)
+        {
+        }
+
+        ~DynamicEntry() { }
+
+        Elf32_Sword tag() const { return m_dyn.d_tag; }
+        Elf32_Addr ptr() const { return m_dyn.d_un.d_ptr; }
+        Elf32_Word val() const { return m_dyn.d_un.d_val; }
+
+    private:
+        const Elf32_Dyn& m_dyn;
+    };
+
+    class Symbol {
+    public:
+        Symbol(const DynamicObject& dynamic, unsigned index, const Elf32_Sym& sym)
+            : m_dynamic(dynamic)
+            , m_sym(sym)
+            , m_index(index)
+        {
+            if (section_index() == 0)
+                m_is_undefined = true;
+        }
+
+        Symbol(const Symbol& other)
+            : m_dynamic(other.m_dynamic)
+            , m_sym(other.m_sym)
+            , m_index(other.m_index)
+            , m_is_undefined(other.m_is_undefined)
+        {
+        }
+
+        static Symbol create_undefined(const DynamicObject& dynamic)
+        {
+            auto s = Symbol(dynamic, 0, {});
+            s.m_is_undefined = true;
+            return s;
+        }
+
+        ~Symbol() { }
+
+        const char* name() const { return m_dynamic.symbol_string_table_string(m_sym.st_name); }
+        unsigned section_index() const { return m_sym.st_shndx; }
+        unsigned value() const { return m_sym.st_value; }
+        unsigned size() const { return m_sym.st_size; }
+        unsigned index() const { return m_index; }
+        unsigned type() const { return ELF32_ST_TYPE(m_sym.st_info); }
+        unsigned bind() const { return ELF32_ST_BIND(m_sym.st_info); }
+
+        bool is_undefined() const
+        {
+            return m_is_undefined;
+        }
+        VirtualAddress address() const
+        {
+            if (m_dynamic.elf_is_dynamic())
+                return m_dynamic.base_address().offset(value());
+            return VirtualAddress { value() };
+        }
+        const DynamicObject& object() const { return m_dynamic; }
+
+    private:
+        const DynamicObject& m_dynamic;
+        const Elf32_Sym& m_sym;
+        const unsigned m_index;
+        bool m_is_undefined { false };
+    };
+
+    class Section {
+    public:
+        Section(const DynamicObject& dynamic, unsigned section_offset, unsigned section_size_bytes, unsigned entry_size, const char* name)
+            : m_dynamic(dynamic)
+            , m_section_offset(section_offset)
+            , m_section_size_bytes(section_size_bytes)
+            , m_entry_size(entry_size)
+            , m_name(name)
+        {
+        }
+        ~Section() { }
+
+        const char* name() const { return m_name; }
+        unsigned offset() const { return m_section_offset; }
+        unsigned size() const { return m_section_size_bytes; }
+        unsigned entry_size() const { return m_entry_size; }
+        unsigned entry_count() const
+        {
+            return !entry_size() ? 0 : size() / entry_size();
+        }
+        VirtualAddress address() const
+        {
+            return m_dynamic.base_address().offset(m_section_offset);
+        }
+
+    protected:
+        friend class RelocationSection;
+        friend class HashSection;
+        const DynamicObject& m_dynamic;
+        unsigned m_section_offset;
+        unsigned m_section_size_bytes;
+        unsigned m_entry_size;
+        const char* m_name { nullptr };
+    };
+
+    class RelocationSection : public Section {
+    public:
+        RelocationSection(const Section& section)
+            : Section(section.m_dynamic, section.m_section_offset, section.m_section_size_bytes, section.m_entry_size, section.m_name)
+        {
+        }
+        unsigned relocation_count() const { return entry_count(); }
+        const Relocation relocation(unsigned index) const;
+        const Relocation relocation_at_offset(unsigned offset) const;
+        template<typename F>
+        void for_each_relocation(F) const;
+    };
+
+    class Relocation {
+    public:
+        Relocation(const DynamicObject& dynamic, const Elf32_Rel& rel, unsigned offset_in_section)
+            : m_dynamic(dynamic)
+            , m_rel(rel)
+            , m_offset_in_section(offset_in_section)
+        {
+        }
+
+        ~Relocation() { }
+
+        unsigned offset_in_section() const { return m_offset_in_section; }
+        unsigned offset() const { return m_rel.r_offset; }
+        unsigned type() const { return ELF32_R_TYPE(m_rel.r_info); }
+        unsigned symbol_index() const { return ELF32_R_SYM(m_rel.r_info); }
+        const Symbol symbol() const { return m_dynamic.symbol(symbol_index()); }
+        VirtualAddress address() const
+        {
+            if (m_dynamic.elf_is_dynamic())
+                return m_dynamic.base_address().offset(offset());
+            return VirtualAddress { offset() };
+        }
+
+    private:
+        const DynamicObject& m_dynamic;
+        const Elf32_Rel& m_rel;
+        const unsigned m_offset_in_section;
+    };
+
+    enum class HashType {
+        SYSV,
+        GNU
+    };
+
+    class HashSection : public Section {
+    public:
+        HashSection(const Section& section, HashType hash_type)
+            : Section(section.m_dynamic, section.m_section_offset, section.m_section_size_bytes, section.m_entry_size, section.m_name)
+        {
+            switch (hash_type) {
+            case HashType::SYSV:
+                m_lookup_function = &HashSection::lookup_elf_symbol;
+                break;
+            case HashType::GNU:
+                m_lookup_function = &HashSection::lookup_gnu_symbol;
+                break;
+            default:
+                ASSERT_NOT_REACHED();
+                break;
+            }
+        }
+
+        const Symbol lookup_symbol(const char*) const;
+
+    private:
+        u32 calculate_elf_hash(const char* name) const;
+        u32 calculate_gnu_hash(const char* name) const;
+
+        const DynamicObject::Symbol lookup_elf_symbol(const char* name) const;
+        const DynamicObject::Symbol lookup_gnu_symbol(const char* name) const;
+
+        typedef const DynamicObject::Symbol (HashSection::*LookupFunction)(const char*) const;
+        LookupFunction m_lookup_function;
+    };
+
+    unsigned symbol_count() const { return m_symbol_count; }
+
+    const Symbol symbol(unsigned) const;
+
+    typedef void (*InitializationFunction)();
+
+    bool has_init_section() const { return m_init_offset != 0; }
+    bool has_init_array_section() const { return m_init_array_offset != 0; }
+    const Section init_section() const;
+    InitializationFunction init_section_function() const;
+    const Section fini_section() const;
+    const Section init_array_section() const;
+    const Section fini_array_section() const;
+
+    const HashSection hash_section() const;
+
+    const RelocationSection relocation_section() const;
+    const RelocationSection plt_relocation_section() const;
+
+    bool should_process_origin() const { return m_dt_flags & DF_ORIGIN; }
+    bool requires_symbolic_symbol_resolution() const { return m_dt_flags & DF_SYMBOLIC; }
+    // Text relocations meaning: we need to edit the .text section which is normally mapped PROT_READ
+    bool has_text_relocations() const { return m_dt_flags & DF_TEXTREL; }
+    bool must_bind_now() const { return m_dt_flags & DF_BIND_NOW; }
+    bool has_static_thread_local_storage() const { return m_dt_flags & DF_STATIC_TLS; }
+
+    VirtualAddress plt_got_base_address() const { return m_base_address.offset(m_procedure_linkage_table_offset); }
+    VirtualAddress base_address() const { return m_base_address; }
+
+    const char* soname() const { return m_has_soname ? symbol_string_table_string(m_soname_index) : nullptr; }
+
+    Optional<FlatPtr> tls_offset() const { return m_tls_offset; }
+    Optional<FlatPtr> tls_size() const { return m_tls_size; }
+    void set_tls_offset(FlatPtr offset) { m_tls_offset = offset; }
+    void set_tls_size(FlatPtr size) { m_tls_size = size; }
+
+    template<typename F>
+    void for_each_needed_library(F) const;
+
+    template<typename F>
+    void for_each_initialization_array_function(F f) const;
+
+    struct SymbolLookupResult {
+        bool found { false };
+        FlatPtr value { 0 };
+        FlatPtr address { 0 };
+        unsigned bind { STB_LOCAL };
+        const ELF::DynamicObject* dynamic_object { nullptr }; // The object in which the symbol is defined
+    };
+    SymbolLookupResult lookup_symbol(const char* name) const;
+
+    // Will be called from _fixup_plt_entry, as part of the PLT trampoline
+    Elf32_Addr patch_plt_entry(u32 relocation_offset);
+
+    SymbolLookupResult lookup_symbol(const ELF::DynamicObject::Symbol& symbol) const;
+    using SymbolLookupFunction = DynamicObject::SymbolLookupResult (*)(const char*);
+    SymbolLookupFunction m_global_symbol_lookup_func { nullptr };
+
+    bool elf_is_dynamic() const { return m_is_elf_dynamic; }
+
+private:
+    explicit DynamicObject(VirtualAddress base_address, VirtualAddress dynamic_section_address);
+
+    const char* symbol_string_table_string(Elf32_Word) const;
+    void parse();
+
+    template<typename F>
+    void for_each_symbol(F) const;
+
+    template<typename F>
+    void for_each_dynamic_entry(F) const;
+
+    VirtualAddress m_base_address;
+    VirtualAddress m_dynamic_address;
+    VirtualAddress m_elf_base_address;
+
+    unsigned m_symbol_count { 0 };
+
+    // Begin Section information collected from DT_* entries
+    FlatPtr m_init_offset { 0 };
+    FlatPtr m_fini_offset { 0 };
+
+    FlatPtr m_init_array_offset { 0 };
+    size_t m_init_array_size { 0 };
+    FlatPtr m_fini_array_offset { 0 };
+    size_t m_fini_array_size { 0 };
+
+    FlatPtr m_hash_table_offset { 0 };
+    HashType m_hash_type { HashType::SYSV };
+
+    FlatPtr m_string_table_offset { 0 };
+    size_t m_size_of_string_table { 0 };
+    FlatPtr m_symbol_table_offset { 0 };
+    size_t m_size_of_symbol_table_entry { 0 };
+
+    Elf32_Sword m_procedure_linkage_table_relocation_type { -1 };
+    FlatPtr m_plt_relocation_offset_location { 0 }; // offset of PLT relocations, at end of relocations
+    size_t m_size_of_plt_relocation_entry_list { 0 };
+    FlatPtr m_procedure_linkage_table_offset { 0 };
+
+    // NOTE: We'll only ever either RELA or REL entries, not both (thank god)
+    // NOTE: The x86 ABI will only ever genrerate REL entries.
+    size_t m_number_of_relocations { 0 };
+    size_t m_size_of_relocation_entry { 0 };
+    size_t m_size_of_relocation_table { 0 };
+    FlatPtr m_relocation_table_offset { 0 };
+    bool m_is_elf_dynamic { false };
+
+    // DT_FLAGS
+    Elf32_Word m_dt_flags { 0 };
+
+    bool m_has_soname { false };
+    Elf32_Word m_soname_index { 0 }; // Index into dynstr table for SONAME
+
+    Optional<FlatPtr> m_tls_offset;
+    Optional<FlatPtr> m_tls_size;
+    // End Section information from DT_* entries
+};
+
+template<typename F>
+inline void DynamicObject::RelocationSection::for_each_relocation(F func) const
+{
+    for (unsigned i = 0; i < relocation_count(); ++i) {
+        const auto reloc = relocation(i);
+        if (reloc.type() == 0)
+            continue;
+        if (func(reloc) == IterationDecision::Break)
+            break;
+    }
+}
+
+template<typename F>
+inline void DynamicObject::for_each_symbol(F func) const
+{
+    for (unsigned i = 0; i < symbol_count(); ++i) {
+        if (func(symbol(i)) == IterationDecision::Break)
+            break;
+    }
+}
+
+template<typename F>
+inline void DynamicObject::for_each_dynamic_entry(F func) const
+{
+    auto* dyns = reinterpret_cast<const Elf32_Dyn*>(m_dynamic_address.as_ptr());
+    for (unsigned i = 0;; ++i) {
+        auto&& dyn = DynamicEntry(dyns[i]);
+        if (dyn.tag() == DT_NULL)
+            break;
+        if (func(dyn) == IterationDecision::Break)
+            break;
+    }
+}
+template<typename F>
+inline void DynamicObject::for_each_needed_library(F func) const
+{
+    for_each_dynamic_entry([func, this](auto entry) {
+        if (entry.tag() != DT_NEEDED)
+            return IterationDecision::Continue;
+        Elf32_Word offset = entry.val();
+        const char* name = (const char*)(m_base_address.offset(m_string_table_offset).offset(offset)).as_ptr();
+        if (func(StringView(name)) == IterationDecision::Break)
+            return IterationDecision::Break;
+        return IterationDecision::Continue;
+    });
+}
+
+template<typename F>
+void DynamicObject::for_each_initialization_array_function(F f) const
+{
+    if (!has_init_array_section())
+        return;
+    FlatPtr init_array = (FlatPtr)init_array_section().address().as_ptr();
+    for (size_t i = 0; i < (m_init_array_size / sizeof(void*)); ++i) {
+        InitializationFunction current = ((InitializationFunction*)(init_array))[i];
+        f(current);
+    }
+}
+
+} // end namespace ELF

Userland/Libraries/LibELF/Image.cpp

@@ -0,0 +1,419 @@
+/*
+ * Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <AK/Demangle.h>
+#include <AK/Memory.h>
+#include <AK/QuickSort.h>
+#include <AK/StringBuilder.h>
+#include <AK/StringView.h>
+#include <LibELF/Image.h>
+#include <LibELF/Validation.h>
+
+//#define ELF_IMAGE_DEBUG
+
+namespace ELF {
+
+Image::Image(ReadonlyBytes bytes, bool verbose_logging)
+    : m_buffer(bytes.data())
+    , m_size(bytes.size())
+    , m_verbose_logging(verbose_logging)
+{
+    parse();
+}
+
+Image::Image(const u8* buffer, size_t size, bool verbose_logging)
+    : Image(ReadonlyBytes { buffer, size }, verbose_logging)
+{
+}
+
+Image::~Image()
+{
+}
+
+#ifdef ELF_IMAGE_DEBUG
+static const char* object_file_type_to_string(Elf32_Half type)
+{
+    switch (type) {
+    case ET_NONE:
+        return "None";
+    case ET_REL:
+        return "Relocatable";
+    case ET_EXEC:
+        return "Executable";
+    case ET_DYN:
+        return "Shared object";
+    case ET_CORE:
+        return "Core";
+    default:
+        return "(?)";
+    }
+}
+#endif
+
+StringView Image::section_index_to_string(unsigned index) const
+{
+    ASSERT(m_valid);
+    if (index == SHN_UNDEF)
+        return "Undefined";
+    if (index >= SHN_LORESERVE)
+        return "Reserved";
+    return section(index).name();
+}
+
+unsigned Image::symbol_count() const
+{
+    ASSERT(m_valid);
+    if (!section_count())
+        return 0;
+    return section(m_symbol_table_section_index).entry_count();
+}
+
+void Image::dump() const
+{
+#ifdef ELF_IMAGE_DEBUG
+    dbgln("ELF::Image({:p}) {{", this);
+    dbgln("    is_valid: {}", is_valid());
+
+    if (!is_valid()) {
+        dbgln("}}");
+        return;
+    }
+
+    dbgln("    type:    {}", object_file_type_to_string(header().e_type));
+    dbgln("    machine: {}", header().e_machine);
+    dbgln("    entry:   {:x}", header().e_entry);
+    dbgln("    shoff:   {}", header().e_shoff);
+    dbgln("    shnum:   {}", header().e_shnum);
+    dbgln("    phoff:   {}", header().e_phoff);
+    dbgln("    phnum:   {}", header().e_phnum);
+    dbgln(" shstrndx:   {}", header().e_shstrndx);
+
+    for_each_program_header([&](const ProgramHeader& program_header) {
+        dbgln("    Program Header {}: {{", program_header.index());
+        dbgln("        type: {:x}", program_header.type());
+        dbgln("      offset: {:x}", program_header.offset());
+        dbgln("       flags: {:x}", program_header.flags());
+        dbgln("    }}");
+        return IterationDecision::Continue;
+    });
+
+    for (unsigned i = 0; i < header().e_shnum; ++i) {
+        auto& section = this->section(i);
+        dbgln("    Section {}: {{", i);
+        dbgln("        name: {}", section.name());
+        dbgln("        type: {:x}", section.type());
+        dbgln("      offset: {:x}", section.offset());
+        dbgln("        size: {}", section.size());
+        dbgln("        ");
+        dbgln("    }}");
+    }
+
+    dbgln("Symbol count: {} (table is {})", symbol_count(), m_symbol_table_section_index);
+    for (unsigned i = 1; i < symbol_count(); ++i) {
+        auto& sym = symbol(i);
+        dbgln("Symbol @{}:", i);
+        dbgln("    Name: {}", sym.name());
+        dbgln("    In section: {}", section_index_to_string(sym.section_index()));
+        dbgln("    Value: {}", sym.value());
+        dbgln("    Size: {}", sym.size());
+    }
+
+    dbgln("}}");
+#endif
+}
+
+unsigned Image::section_count() const
+{
+    ASSERT(m_valid);
+    return header().e_shnum;
+}
+
+unsigned Image::program_header_count() const
+{
+    ASSERT(m_valid);
+    return header().e_phnum;
+}
+
+bool Image::parse()
+{
+    if (m_size < sizeof(Elf32_Ehdr) || !validate_elf_header(header(), m_size, m_verbose_logging)) {
+        if (m_verbose_logging)
+            dbgln("ELF::Image::parse(): ELF Header not valid");
+        return m_valid = false;
+    }
+
+    if (!validate_program_headers(header(), m_size, m_buffer, m_size, nullptr, m_verbose_logging)) {
+        if (m_verbose_logging)
+            dbgln("ELF::Image::parse(): ELF Program Headers not valid");
+        return m_valid = false;
+    }
+
+    m_valid = true;
+
+    // First locate the string tables.
+    for (unsigned i = 0; i < section_count(); ++i) {
+        auto& sh = section_header(i);
+        if (sh.sh_type == SHT_SYMTAB) {
+            if (m_symbol_table_section_index && m_symbol_table_section_index != i)
+                return m_valid = false;
+            m_symbol_table_section_index = i;
+        }
+        if (sh.sh_type == SHT_STRTAB && i != header().e_shstrndx) {
+            if (section_header_table_string(sh.sh_name) == ELF_STRTAB)
+                m_string_table_section_index = i;
+        }
+    }
+
+    // Then create a name-to-index map.
+    for (unsigned i = 0; i < section_count(); ++i) {
+        auto& section = this->section(i);
+        m_sections.set(section.name(), move(i));
+    }
+
+    return m_valid;
+}
+
+StringView Image::table_string(unsigned table_index, unsigned offset) const
+{
+    ASSERT(m_valid);
+    auto& sh = section_header(table_index);
+    if (sh.sh_type != SHT_STRTAB)
+        return nullptr;
+    size_t computed_offset = sh.sh_offset + offset;
+    if (computed_offset >= m_size) {
+        if (m_verbose_logging)
+            dbgln("SHENANIGANS! Image::table_string() computed offset outside image.");
+        return {};
+    }
+    size_t max_length = m_size - computed_offset;
+    size_t length = strnlen(raw_data(sh.sh_offset + offset), max_length);
+    return { raw_data(sh.sh_offset + offset), length };
+}
+
+StringView Image::section_header_table_string(unsigned offset) const
+{
+    ASSERT(m_valid);
+    return table_string(header().e_shstrndx, offset);
+}
+
+StringView Image::table_string(unsigned offset) const
+{
+    ASSERT(m_valid);
+    return table_string(m_string_table_section_index, offset);
+}
+
+const char* Image::raw_data(unsigned offset) const
+{
+    ASSERT(offset < m_size); // Callers must check indices into raw_data()'s result are also in bounds.
+    return reinterpret_cast<const char*>(m_buffer) + offset;
+}
+
+const Elf32_Ehdr& Image::header() const
+{
+    ASSERT(m_size >= sizeof(Elf32_Ehdr));
+    return *reinterpret_cast<const Elf32_Ehdr*>(raw_data(0));
+}
+
+const Elf32_Phdr& Image::program_header_internal(unsigned index) const
+{
+    ASSERT(m_valid);
+    ASSERT(index < header().e_phnum);
+    return *reinterpret_cast<const Elf32_Phdr*>(raw_data(header().e_phoff + (index * sizeof(Elf32_Phdr))));
+}
+
+const Elf32_Shdr& Image::section_header(unsigned index) const
+{
+    ASSERT(m_valid);
+    ASSERT(index < header().e_shnum);
+    return *reinterpret_cast<const Elf32_Shdr*>(raw_data(header().e_shoff + (index * header().e_shentsize)));
+}
+
+const Image::Symbol Image::symbol(unsigned index) const
+{
+    ASSERT(m_valid);
+    ASSERT(index < symbol_count());
+    auto* raw_syms = reinterpret_cast<const Elf32_Sym*>(raw_data(section(m_symbol_table_section_index).offset()));
+    return Symbol(*this, index, raw_syms[index]);
+}
+
+const Image::Section Image::section(unsigned index) const
+{
+    ASSERT(m_valid);
+    ASSERT(index < section_count());
+    return Section(*this, index);
+}
+
+const Image::ProgramHeader Image::program_header(unsigned index) const
+{
+    ASSERT(m_valid);
+    ASSERT(index < program_header_count());
+    return ProgramHeader(*this, index);
+}
+
+FlatPtr Image::program_header_table_offset() const
+{
+    return header().e_phoff;
+}
+
+const Image::Relocation Image::RelocationSection::relocation(unsigned index) const
+{
+    ASSERT(index < relocation_count());
+    auto* rels = reinterpret_cast<const Elf32_Rel*>(m_image.raw_data(offset()));
+    return Relocation(m_image, rels[index]);
+}
+
+const Image::RelocationSection Image::Section::relocations() const
+{
+    StringBuilder builder;
+    builder.append(".rel");
+    builder.append(name());
+
+    auto relocation_section = m_image.lookup_section(builder.to_string());
+    if (relocation_section.type() != SHT_REL)
+        return static_cast<const RelocationSection>(m_image.section(0));
+
+#ifdef ELF_IMAGE_DEBUG
+    dbgln("Found relocations for {} in {}", name(), relocation_section.name());
+#endif
+    return static_cast<const RelocationSection>(relocation_section);
+}
+
+const Image::Section Image::lookup_section(const String& name) const
+{
+    ASSERT(m_valid);
+    if (auto it = m_sections.find(name); it != m_sections.end())
+        return section((*it).value);
+    return section(0);
+}
+
+StringView Image::Symbol::raw_data() const
+{
+    auto& section = this->section();
+    return { section.raw_data() + (value() - section.address()), size() };
+}
+
+Optional<Image::Symbol> Image::find_demangled_function(const String& name) const
+{
+    Optional<Image::Symbol> found;
+    for_each_symbol([&](const Image::Symbol symbol) {
+        if (symbol.type() != STT_FUNC)
+            return IterationDecision::Continue;
+        if (symbol.is_undefined())
+            return IterationDecision::Continue;
+        auto demangled = demangle(symbol.name());
+        auto index_of_paren = demangled.index_of("(");
+        if (index_of_paren.has_value()) {
+            demangled = demangled.substring(0, index_of_paren.value());
+        }
+        if (demangled != name)
+            return IterationDecision::Continue;
+        found = symbol;
+        return IterationDecision::Break;
+    });
+    return found;
+}
+
+Optional<Image::Symbol> Image::find_symbol(u32 address, u32* out_offset) const
+{
+    auto symbol_count = this->symbol_count();
+    if (!symbol_count)
+        return {};
+
+    SortedSymbol* sorted_symbols = nullptr;
+    if (m_sorted_symbols.is_empty()) {
+        m_sorted_symbols.ensure_capacity(symbol_count);
+        for_each_symbol([this](auto& symbol) {
+            m_sorted_symbols.append({ symbol.value(), symbol.name(), {}, symbol });
+            return IterationDecision::Continue;
+        });
+        quick_sort(m_sorted_symbols, [](auto& a, auto& b) {
+            return a.address < b.address;
+        });
+    }
+    sorted_symbols = m_sorted_symbols.data();
+
+    for (size_t i = 0; i < symbol_count; ++i) {
+        if (sorted_symbols[i].address > address) {
+            if (i == 0)
+                return {};
+            auto& symbol = sorted_symbols[i - 1];
+            if (out_offset)
+                *out_offset = address - symbol.address;
+            return symbol.symbol;
+        }
+    }
+    return {};
+}
+
+String Image::symbolicate(u32 address, u32* out_offset) const
+{
+    auto symbol_count = this->symbol_count();
+    if (!symbol_count) {
+        if (out_offset)
+            *out_offset = 0;
+        return "??";
+    }
+    SortedSymbol* sorted_symbols = nullptr;
+
+    if (m_sorted_symbols.is_empty()) {
+        m_sorted_symbols.ensure_capacity(symbol_count);
+        for_each_symbol([this](auto& symbol) {
+            m_sorted_symbols.append({ symbol.value(), symbol.name(), {}, symbol });
+            return IterationDecision::Continue;
+        });
+        quick_sort(m_sorted_symbols, [](auto& a, auto& b) {
+            return a.address < b.address;
+        });
+    }
+    sorted_symbols = m_sorted_symbols.data();
+
+    for (size_t i = 0; i < symbol_count; ++i) {
+        if (sorted_symbols[i].address > address) {
+            if (i == 0) {
+                if (out_offset)
+                    *out_offset = 0;
+                return "!!";
+            }
+            auto& symbol = sorted_symbols[i - 1];
+
+            auto& demangled_name = symbol.demangled_name;
+            if (demangled_name.is_null()) {
+                demangled_name = demangle(symbol.name);
+            }
+
+            if (out_offset) {
+                *out_offset = address - symbol.address;
+                return demangled_name;
+            }
+            return String::format("%s +0x%x", demangled_name.characters(), address - symbol.address);
+        }
+    }
+    if (out_offset)
+        *out_offset = 0;
+    return "??";
+}
+
+} // end namespace ELF

Userland/Libraries/LibELF/Image.h

@@ -0,0 +1,299 @@
+/*
+ * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/ByteBuffer.h>
+#include <AK/HashMap.h>
+#include <AK/OwnPtr.h>
+#include <AK/String.h>
+#include <Kernel/VirtualAddress.h>
+#include <LibELF/exec_elf.h>
+
+namespace ELF {
+
+class Image {
+public:
+    explicit Image(ReadonlyBytes, bool verbose_logging = true);
+    explicit Image(const u8*, size_t, bool verbose_logging = true);
+
+    ~Image();
+    void dump() const;
+    bool is_valid() const { return m_valid; }
+    bool parse();
+
+    bool is_within_image(const void* address, size_t size) const
+    {
+        if (address < m_buffer)
+            return false;
+        if (((const u8*)address + size) > m_buffer + m_size)
+            return false;
+        return true;
+    }
+
+    class Section;
+    class RelocationSection;
+    class Symbol;
+    class Relocation;
+
+    class Symbol {
+    public:
+        Symbol(const Image& image, unsigned index, const Elf32_Sym& sym)
+            : m_image(image)
+            , m_sym(sym)
+            , m_index(index)
+        {
+        }
+
+        ~Symbol() { }
+
+        StringView name() const { return m_image.table_string(m_sym.st_name); }
+        unsigned section_index() const { return m_sym.st_shndx; }
+        unsigned value() const { return m_sym.st_value; }
+        unsigned size() const { return m_sym.st_size; }
+        unsigned index() const { return m_index; }
+        unsigned type() const { return ELF32_ST_TYPE(m_sym.st_info); }
+        unsigned bind() const { return ELF32_ST_BIND(m_sym.st_info); }
+        const Section section() const { return m_image.section(section_index()); }
+        bool is_undefined() const { return section_index() == 0; }
+        StringView raw_data() const;
+
+    private:
+        const Image& m_image;
+        const Elf32_Sym& m_sym;
+        const unsigned m_index;
+    };
+
+    class ProgramHeader {
+    public:
+        ProgramHeader(const Image& image, unsigned program_header_index)
+            : m_image(image)
+            , m_program_header(image.program_header_internal(program_header_index))
+            , m_program_header_index(program_header_index)
+        {
+        }
+        ~ProgramHeader() { }
+
+        unsigned index() const { return m_program_header_index; }
+        u32 type() const { return m_program_header.p_type; }
+        u32 flags() const { return m_program_header.p_flags; }
+        u32 offset() const { return m_program_header.p_offset; }
+        VirtualAddress vaddr() const { return VirtualAddress(m_program_header.p_vaddr); }
+        u32 size_in_memory() const { return m_program_header.p_memsz; }
+        u32 size_in_image() const { return m_program_header.p_filesz; }
+        u32 alignment() const { return m_program_header.p_align; }
+        bool is_readable() const { return flags() & PF_R; }
+        bool is_writable() const { return flags() & PF_W; }
+        bool is_executable() const { return flags() & PF_X; }
+        const char* raw_data() const { return m_image.raw_data(m_program_header.p_offset); }
+        Elf32_Phdr raw_header() const { return m_program_header; }
+
+    private:
+        const Image& m_image;
+        const Elf32_Phdr& m_program_header;
+        unsigned m_program_header_index { 0 };
+    };
+
+    class Section {
+    public:
+        Section(const Image& image, unsigned sectionIndex)
+            : m_image(image)
+            , m_section_header(image.section_header(sectionIndex))
+            , m_section_index(sectionIndex)
+        {
+        }
+        ~Section() { }
+
+        StringView name() const { return m_image.section_header_table_string(m_section_header.sh_name); }
+        unsigned type() const { return m_section_header.sh_type; }
+        unsigned offset() const { return m_section_header.sh_offset; }
+        unsigned size() const { return m_section_header.sh_size; }
+        unsigned entry_size() const { return m_section_header.sh_entsize; }
+        unsigned entry_count() const { return !entry_size() ? 0 : size() / entry_size(); }
+        u32 address() const { return m_section_header.sh_addr; }
+        const char* raw_data() const { return m_image.raw_data(m_section_header.sh_offset); }
+        ReadonlyBytes bytes() const { return { raw_data(), size() }; }
+        bool is_undefined() const { return m_section_index == SHN_UNDEF; }
+        const RelocationSection relocations() const;
+        u32 flags() const { return m_section_header.sh_flags; }
+        bool is_writable() const { return flags() & SHF_WRITE; }
+        bool is_executable() const { return flags() & PF_X; }
+
+    protected:
+        friend class RelocationSection;
+        const Image& m_image;
+        const Elf32_Shdr& m_section_header;
+        unsigned m_section_index;
+    };
+
+    class RelocationSection : public Section {
+    public:
+        RelocationSection(const Section& section)
+            : Section(section.m_image, section.m_section_index)
+        {
+        }
+        unsigned relocation_count() const { return entry_count(); }
+        const Relocation relocation(unsigned index) const;
+        template<typename F>
+        void for_each_relocation(F) const;
+    };
+
+    class Relocation {
+    public:
+        Relocation(const Image& image, const Elf32_Rel& rel)
+            : m_image(image)
+            , m_rel(rel)
+        {
+        }
+
+        ~Relocation() { }
+
+        unsigned offset() const { return m_rel.r_offset; }
+        unsigned type() const { return ELF32_R_TYPE(m_rel.r_info); }
+        unsigned symbol_index() const { return ELF32_R_SYM(m_rel.r_info); }
+        const Symbol symbol() const { return m_image.symbol(symbol_index()); }
+
+    private:
+        const Image& m_image;
+        const Elf32_Rel& m_rel;
+    };
+
+    unsigned symbol_count() const;
+    unsigned section_count() const;
+    unsigned program_header_count() const;
+
+    const Symbol symbol(unsigned) const;
+    const Section section(unsigned) const;
+    const ProgramHeader program_header(unsigned const) const;
+    FlatPtr program_header_table_offset() const;
+
+    template<typename F>
+    void for_each_section(F) const;
+    template<typename F>
+    void for_each_section_of_type(unsigned, F) const;
+    template<typename F>
+    void for_each_symbol(F) const;
+    template<typename F>
+    void for_each_program_header(F) const;
+
+    // NOTE: Returns section(0) if section with name is not found.
+    // FIXME: I don't love this API.
+    const Section lookup_section(const String& name) const;
+
+    bool is_executable() const { return header().e_type == ET_EXEC; }
+    bool is_relocatable() const { return header().e_type == ET_REL; }
+    bool is_dynamic() const { return header().e_type == ET_DYN; }
+
+    VirtualAddress entry() const { return VirtualAddress(header().e_entry); }
+    FlatPtr base_address() const { return (FlatPtr)m_buffer; }
+    size_t size() const { return m_size; }
+
+    Optional<Symbol> find_demangled_function(const String& name) const;
+
+    bool has_symbols() const { return symbol_count(); }
+    String symbolicate(u32 address, u32* offset = nullptr) const;
+    Optional<Image::Symbol> find_symbol(u32 address, u32* offset = nullptr) const;
+
+private:
+    const char* raw_data(unsigned offset) const;
+    const Elf32_Ehdr& header() const;
+    const Elf32_Shdr& section_header(unsigned) const;
+    const Elf32_Phdr& program_header_internal(unsigned) const;
+    StringView table_string(unsigned offset) const;
+    StringView section_header_table_string(unsigned offset) const;
+    StringView section_index_to_string(unsigned index) const;
+    StringView table_string(unsigned table_index, unsigned offset) const;
+
+    const u8* m_buffer { nullptr };
+    size_t m_size { 0 };
+    bool m_verbose_logging { true };
+    HashMap<String, unsigned> m_sections;
+    bool m_valid { false };
+    unsigned m_symbol_table_section_index { 0 };
+    unsigned m_string_table_section_index { 0 };
+
+    struct SortedSymbol {
+        u32 address;
+        StringView name;
+        String demangled_name;
+        Optional<Image::Symbol> symbol;
+    };
+
+    mutable Vector<SortedSymbol> m_sorted_symbols;
+};
+
+template<typename F>
+inline void Image::for_each_section(F func) const
+{
+    auto section_count = this->section_count();
+    for (unsigned i = 0; i < section_count; ++i)
+        func(section(i));
+}
+
+template<typename F>
+inline void Image::for_each_section_of_type(unsigned type, F func) const
+{
+    auto section_count = this->section_count();
+    for (unsigned i = 0; i < section_count; ++i) {
+        auto& section = this->section(i);
+        if (section.type() == type) {
+            if (func(section) == IterationDecision::Break)
+                break;
+        }
+    }
+}
+
+template<typename F>
+inline void Image::RelocationSection::for_each_relocation(F func) const
+{
+    auto relocation_count = this->relocation_count();
+    for (unsigned i = 0; i < relocation_count; ++i) {
+        if (func(relocation(i)) == IterationDecision::Break)
+            break;
+    }
+}
+
+template<typename F>
+inline void Image::for_each_symbol(F func) const
+{
+    auto symbol_count = this->symbol_count();
+    for (unsigned i = 0; i < symbol_count; ++i) {
+        if (func(symbol(i)) == IterationDecision::Break)
+            break;
+    }
+}
+
+template<typename F>
+inline void Image::for_each_program_header(F func) const
+{
+    auto program_header_count = this->program_header_count();
+    for (unsigned i = 0; i < program_header_count; ++i) {
+        if (func(program_header(i)) == IterationDecision::Break)
+            return;
+    }
+}
+
+} // end namespace ELF

Userland/Libraries/LibELF/Validation.cpp

@@ -0,0 +1,267 @@
+/*
+ * Copyright (c) 2020, Andrew Kaster <andrewdkaster@gmail.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <AK/Assertions.h>
+#include <AK/String.h>
+#include <LibELF/Validation.h>
+#include <LibELF/exec_elf.h>
+
+namespace ELF {
+
+bool validate_elf_header(const Elf32_Ehdr& elf_header, size_t file_size, bool verbose)
+{
+    if (!IS_ELF(elf_header)) {
+        if (verbose)
+            dbgln("File is not an ELF file.");
+        return false;
+    }
+
+    if (ELFCLASS32 != elf_header.e_ident[EI_CLASS]) {
+        if (verbose)
+            dbgln("File is not a 32 bit ELF file.");
+        return false;
+    }
+
+    if (ELFDATA2LSB != elf_header.e_ident[EI_DATA]) {
+        if (verbose)
+            dbgln("File is not a little endian ELF file.");
+        return false;
+    }
+
+    if (EV_CURRENT != elf_header.e_ident[EI_VERSION]) {
+        if (verbose)
+            dbgln("File has unrecognized ELF version ({}), expected ({})!", elf_header.e_ident[EI_VERSION], EV_CURRENT);
+        return false;
+    }
+
+    if (ELFOSABI_SYSV != elf_header.e_ident[EI_OSABI]) {
+        if (verbose)
+            dbgln("File has unknown OS ABI ({}), expected SYSV(0)!", elf_header.e_ident[EI_OSABI]);
+        return false;
+    }
+
+    if (0 != elf_header.e_ident[EI_ABIVERSION]) {
+        if (verbose)
+            dbgln("File has unknown SYSV ABI version ({})!", elf_header.e_ident[EI_ABIVERSION]);
+        return false;
+    }
+
+    if (EM_386 != elf_header.e_machine) {
+        if (verbose)
+            dbgln("File has unknown machine ({}), expected i386 (3)!", elf_header.e_machine);
+        return false;
+    }
+
+    if (ET_EXEC != elf_header.e_type && ET_DYN != elf_header.e_type && ET_REL != elf_header.e_type && ET_CORE != elf_header.e_type) {
+        if (verbose)
+            dbgln("File has unloadable ELF type ({}), expected REL (1), EXEC (2), DYN (3) or CORE(4)!", elf_header.e_type);
+        return false;
+    }
+
+    if (EV_CURRENT != elf_header.e_version) {
+        if (verbose)
+            dbgln("File has unrecognized ELF version ({}), expected ({})!", elf_header.e_version, EV_CURRENT);
+        return false;
+    }
+
+    if (sizeof(Elf32_Ehdr) != elf_header.e_ehsize) {
+        if (verbose)
+            dbgln("File has incorrect ELF header size..? ({}), expected ({})!", elf_header.e_ehsize, sizeof(Elf32_Ehdr));
+        return false;
+    }
+
+    if (elf_header.e_phoff < elf_header.e_ehsize || (elf_header.e_shnum != SHN_UNDEF && elf_header.e_shoff < elf_header.e_ehsize)) {
+        if (verbose) {
+            dbgln("SHENANIGANS! program header offset ({}) or section header offset ({}) overlap with ELF header!",
+                elf_header.e_phoff, elf_header.e_shoff);
+        }
+        return false;
+    }
+
+    if (elf_header.e_phoff > file_size || elf_header.e_shoff > file_size) {
+        if (verbose) {
+            dbgln("SHENANIGANS! program header offset ({}) or section header offset ({}) are past the end of the file!",
+                elf_header.e_phoff, elf_header.e_shoff);
+        }
+        return false;
+    }
+
+    if (elf_header.e_phnum == 0 && elf_header.e_phoff != 0) {
+        if (verbose)
+            dbgln("SHENANIGANS! File has no program headers, but it does have a program header offset ({})!", elf_header.e_phoff);
+        return false;
+    }
+
+    if (elf_header.e_phnum != 0 && elf_header.e_phoff != elf_header.e_ehsize) {
+        if (verbose) {
+            dbgln("File does not have program headers directly after the ELF header? program header offset ({}), expected ({}).",
+                elf_header.e_phoff, elf_header.e_ehsize);
+        }
+        return false;
+    }
+
+    if (0 != elf_header.e_flags) {
+        if (verbose)
+            dbgln("File has incorrect ELF header flags...? ({}), expected ({}).", elf_header.e_flags, 0);
+        return false;
+    }
+
+    if (0 != elf_header.e_phnum && sizeof(Elf32_Phdr) != elf_header.e_phentsize) {
+        if (verbose)
+            dbgln("File has incorrect program header size..? ({}), expected ({}).", elf_header.e_phentsize, sizeof(Elf32_Phdr));
+        return false;
+    }
+
+    if (sizeof(Elf32_Shdr) != elf_header.e_shentsize) {
+        if (verbose)
+            dbgln("File has incorrect section header size..? ({}), expected ({}).", elf_header.e_shentsize, sizeof(Elf32_Shdr));
+        return false;
+    }
+
+    size_t end_of_last_program_header = elf_header.e_phoff + (elf_header.e_phnum * elf_header.e_phentsize);
+    if (end_of_last_program_header > file_size) {
+        if (verbose)
+            dbgln("SHENANIGANS! End of last program header ({}) is past the end of the file!", end_of_last_program_header);
+        return false;
+    }
+
+    if (elf_header.e_shoff != SHN_UNDEF && elf_header.e_shoff < end_of_last_program_header) {
+        if (verbose) {
+            dbgln("SHENANIGANS! Section header table begins at file offset {}, which is within program headers [ {} - {} ]!",
+                elf_header.e_shoff, elf_header.e_phoff, end_of_last_program_header);
+        }
+        return false;
+    }
+
+    size_t end_of_last_section_header = elf_header.e_shoff + (elf_header.e_shnum * elf_header.e_shentsize);
+    if (end_of_last_section_header > file_size) {
+        if (verbose)
+            dbgln("SHENANIGANS! End of last section header ({}) is past the end of the file!", end_of_last_section_header);
+        return false;
+    }
+
+    if (elf_header.e_shstrndx != SHN_UNDEF && elf_header.e_shstrndx >= elf_header.e_shnum) {
+        if (verbose)
+            dbgln("SHENANIGANS! Section header string table index ({}) is not a valid index given we have {} section headers!", elf_header.e_shstrndx, elf_header.e_shnum);
+        return false;
+    }
+
+    return true;
+}
+
+bool validate_program_headers(const Elf32_Ehdr& elf_header, size_t file_size, const u8* buffer, size_t buffer_size, String* interpreter_path, bool verbose)
+{
+    // Can we actually parse all the program headers in the given buffer?
+    size_t end_of_last_program_header = elf_header.e_phoff + (elf_header.e_phnum * elf_header.e_phentsize);
+    if (end_of_last_program_header > buffer_size) {
+        if (verbose)
+            dbgln("Unable to parse program headers from buffer, buffer too small! Buffer size: {}, End of program headers {}",
+                buffer_size, end_of_last_program_header);
+        return false;
+    }
+
+    if (file_size < buffer_size) {
+        dbgln("We somehow read more from a file than was in the file in the first place!");
+        ASSERT_NOT_REACHED();
+    }
+
+    size_t num_program_headers = elf_header.e_phnum;
+    auto program_header_begin = (const Elf32_Phdr*)&(buffer[elf_header.e_phoff]);
+
+    for (size_t header_index = 0; header_index < num_program_headers; ++header_index) {
+        auto& program_header = program_header_begin[header_index];
+
+        if (program_header.p_filesz > program_header.p_memsz) {
+            if (verbose)
+                dbgln("Program header ({}) has p_filesz ({}) larger than p_memsz ({})", header_index, program_header.p_filesz, program_header.p_memsz);
+            return false;
+        }
+
+        if (program_header.p_memsz <= 0 && (program_header.p_type == PT_TLS || program_header.p_type == PT_LOAD)) {
+            if (verbose)
+                dbgln("Program header ({}) has invalid size in memory ({})", header_index, program_header.p_memsz);
+            return false;
+        }
+
+        if (program_header.p_type == PT_LOAD && program_header.p_align != PAGE_SIZE) {
+            if (elf_header.e_type != ET_CORE) {
+                if (verbose)
+                    dbgln("Program header ({}) with p_type PT_LOAD has p_align ({}) not equal to page size ({})", header_index, program_header.p_align, PAGE_SIZE);
+                return false;
+            }
+        }
+
+        switch (program_header.p_type) {
+        case PT_INTERP:
+            // We checked above that file_size was >= buffer size. We only care about buffer size anyway, we're trying to read this!
+            if (program_header.p_offset + program_header.p_filesz > buffer_size) {
+                if (verbose)
+                    dbgln("Found PT_INTERP header ({}), but the .interp section was not within the buffer :(", header_index);
+                return false;
+            }
+            if (interpreter_path)
+                *interpreter_path = String((const char*)&buffer[program_header.p_offset], program_header.p_filesz - 1);
+            break;
+        case PT_LOAD:
+        case PT_DYNAMIC:
+        case PT_NOTE:
+        case PT_PHDR:
+        case PT_TLS:
+            if (program_header.p_offset + program_header.p_filesz > file_size) {
+                if (verbose)
+                    dbgln("SHENANIGANS! Program header {} segment leaks beyond end of file!", header_index);
+                return false;
+            }
+            if ((program_header.p_flags & PF_X) && (program_header.p_flags & PF_W)) {
+                if (verbose)
+                    dbgln("SHENANIGANS! Program header {} segment is marked write and execute", header_index);
+                return false;
+            }
+            break;
+        case PT_GNU_STACK:
+            if (program_header.p_flags & PF_X) {
+                if (verbose)
+                    dbgln("Possible shenanigans! Validating an ELF with executable stack.");
+            }
+            break;
+        case PT_GNU_RELRO:
+            if ((program_header.p_flags & PF_X) && (program_header.p_flags & PF_W)) {
+                if (verbose)
+                    dbgln("SHENANIGANS! Program header {} segment is marked write and execute", header_index);
+                return false;
+            }
+            break;
+        default:
+            // Not handling other program header types in other code so... let's not surprise them
+            if (verbose)
+                dbgln("Found program header ({}) of unrecognized type {}!", header_index, program_header.p_type);
+            return false;
+        }
+    }
+    return true;
+}
+
+} // end namespace ELF

Userland/Libraries/LibELF/Validation.h

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2020, Andrew Kaster <andrewdkaster@gmail.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <LibELF/exec_elf.h>
+
+namespace ELF {
+
+bool validate_elf_header(const Elf32_Ehdr& elf_header, size_t file_size, bool verbose = true);
+bool validate_program_headers(const Elf32_Ehdr& elf_header, size_t file_size, const u8* buffer, size_t buffer_size, String* interpreter_path, bool verbose = true);
+
+} // end namespace ELF

Userland/Libraries/LibELF/exec_elf.h

@@ -0,0 +1,792 @@
+/*	$OpenBSD: exec_elf.h,v 1.83 2019/01/22 23:23:18 jsg Exp $	*/
+/*
+ * Copyright (c) 1995, 1996 Erik Theisen.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/*
+ * This is the ELF ABI header file
+ * formerly known as "elf_abi.h".
+ */
+
+#ifndef _SYS_EXEC_ELF_H_
+#define _SYS_EXEC_ELF_H_
+
+#include <AK/Types.h>
+
+typedef uint8_t Elf_Byte;
+
+typedef uint32_t Elf32_Addr; /* Unsigned program address */
+typedef uint32_t Elf32_Off;  /* Unsigned file offset */
+typedef int32_t Elf32_Sword; /* Signed large integer */
+typedef uint32_t Elf32_Word; /* Unsigned large integer */
+typedef uint16_t Elf32_Half; /* Unsigned medium integer */
+typedef uint64_t Elf32_Lword;
+
+typedef uint64_t Elf64_Addr;
+typedef uint64_t Elf64_Off;
+typedef int32_t Elf64_Shalf;
+
+#ifdef __alpha__
+typedef int64_t Elf64_Sword;
+typedef uint64_t Elf64_Word;
+#else
+typedef int32_t Elf64_Sword;
+typedef uint32_t Elf64_Word;
+#endif
+
+typedef int64_t Elf64_Sxword;
+typedef uint64_t Elf64_Xword;
+typedef uint64_t Elf64_Lword;
+
+typedef uint32_t Elf64_Half;
+typedef uint16_t Elf64_Quarter;
+
+/*
+ * e_ident[] identification indexes
+ * See http://www.sco.com/developers/gabi/latest/ch4.eheader.html
+ */
+#define EI_MAG0 0       /* file ID */
+#define EI_MAG1 1       /* file ID */
+#define EI_MAG2 2       /* file ID */
+#define EI_MAG3 3       /* file ID */
+#define EI_CLASS 4      /* file class */
+#define EI_DATA 5       /* data encoding */
+#define EI_VERSION 6    /* ELF header version */
+#define EI_OSABI 7      /* OS/ABI ID */
+#define EI_ABIVERSION 8 /* ABI version */
+#define EI_PAD 9        /* start of pad bytes */
+#define EI_NIDENT 16    /* Gfx::Size of e_ident[] */
+
+/* e_ident[] magic number */
+#define ELFMAG0 0x7f     /* e_ident[EI_MAG0] */
+#define ELFMAG1 'E'      /* e_ident[EI_MAG1] */
+#define ELFMAG2 'L'      /* e_ident[EI_MAG2] */
+#define ELFMAG3 'F'      /* e_ident[EI_MAG3] */
+#define ELFMAG "\177ELF" /* magic */
+#define SELFMAG 4        /* size of magic */
+
+/* e_ident[] file class */
+#define ELFCLASSNONE 0 /* invalid */
+#define ELFCLASS32 1   /* 32-bit objs */
+#define ELFCLASS64 2   /* 64-bit objs */
+#define ELFCLASSNUM 3  /* number of classes */
+
+/* e_ident[] data encoding */
+#define ELFDATANONE 0 /* invalid */
+#define ELFDATA2LSB 1 /* Little-Endian */
+#define ELFDATA2MSB 2 /* Big-Endian */
+#define ELFDATANUM 3  /* number of data encode defines */
+
+/* e_ident[] Operating System/ABI */
+#define ELFOSABI_SYSV 0         /* UNIX System V ABI */
+#define ELFOSABI_HPUX 1         /* HP-UX operating system */
+#define ELFOSABI_NETBSD 2       /* NetBSD */
+#define ELFOSABI_LINUX 3        /* GNU/Linux */
+#define ELFOSABI_HURD 4         /* GNU/Hurd */
+#define ELFOSABI_86OPEN 5       /* 86Open common IA32 ABI */
+#define ELFOSABI_SOLARIS 6      /* Solaris */
+#define ELFOSABI_MONTEREY 7     /* Monterey */
+#define ELFOSABI_IRIX 8         /* IRIX */
+#define ELFOSABI_FREEBSD 9      /* FreeBSD */
+#define ELFOSABI_TRU64 10       /* TRU64 UNIX */
+#define ELFOSABI_MODESTO 11     /* Novell Modesto */
+#define ELFOSABI_OPENBSD 12     /* OpenBSD */
+#define ELFOSABI_ARM 97         /* ARM */
+#define ELFOSABI_STANDALONE 255 /* Standalone (embedded) application */
+
+/* e_ident */
+#define IS_ELF(ehdr) ((ehdr).e_ident[EI_MAG0] == ELFMAG0 && (ehdr).e_ident[EI_MAG1] == ELFMAG1 && (ehdr).e_ident[EI_MAG2] == ELFMAG2 && (ehdr).e_ident[EI_MAG3] == ELFMAG3)
+
+/* ELF Header */
+typedef struct elfhdr {
+    unsigned char e_ident[EI_NIDENT]; /* ELF Identification */
+    Elf32_Half e_type;                /* object file type */
+    Elf32_Half e_machine;             /* machine */
+    Elf32_Word e_version;             /* object file version */
+    Elf32_Addr e_entry;               /* virtual entry point */
+    Elf32_Off e_phoff;                /* program header table offset */
+    Elf32_Off e_shoff;                /* section header table offset */
+    Elf32_Word e_flags;               /* processor-specific flags */
+    Elf32_Half e_ehsize;              /* ELF header size */
+    Elf32_Half e_phentsize;           /* program header entry size */
+    Elf32_Half e_phnum;               /* number of program header entries */
+    Elf32_Half e_shentsize;           /* section header entry size */
+    Elf32_Half e_shnum;               /* number of section header entries */
+    Elf32_Half e_shstrndx;            /* section header table's "section
+					   header string table" entry offset */
+} Elf32_Ehdr;
+
+typedef struct {
+    unsigned char e_ident[EI_NIDENT]; /* Id bytes */
+    Elf64_Quarter e_type;             /* file type */
+    Elf64_Quarter e_machine;          /* machine type */
+    Elf64_Half e_version;             /* version number */
+    Elf64_Addr e_entry;               /* entry point */
+    Elf64_Off e_phoff;                /* Program hdr offset */
+    Elf64_Off e_shoff;                /* Section hdr offset */
+    Elf64_Half e_flags;               /* Processor flags */
+    Elf64_Quarter e_ehsize;           /* sizeof ehdr */
+    Elf64_Quarter e_phentsize;        /* Program header entry size */
+    Elf64_Quarter e_phnum;            /* Number of program headers */
+    Elf64_Quarter e_shentsize;        /* Section header entry size */
+    Elf64_Quarter e_shnum;            /* Number of section headers */
+    Elf64_Quarter e_shstrndx;         /* String table index */
+} Elf64_Ehdr;
+
+/* e_type */
+#define ET_NONE 0        /* No file type */
+#define ET_REL 1         /* relocatable file */
+#define ET_EXEC 2        /* executable file */
+#define ET_DYN 3         /* shared object file */
+#define ET_CORE 4        /* core file */
+#define ET_NUM 5         /* number of types */
+#define ET_LOPROC 0xff00 /* reserved range for processor */
+#define ET_HIPROC 0xffff /*  specific e_type */
+
+/* e_machine */
+#define EM_NONE 0  /* No Machine */
+#define EM_M32 1   /* AT&T WE 32100 */
+#define EM_SPARC 2 /* SPARC */
+#define EM_386 3   /* Intel 80386 */
+#define EM_68K 4   /* Motorola 68000 */
+#define EM_88K 5   /* Motorola 88000 */
+#define EM_486 6   /* Intel 80486 - unused? */
+#define EM_860 7   /* Intel 80860 */
+#define EM_MIPS 8  /* MIPS R3000 Big-Endian only */
+/*
+ * Don't know if EM_MIPS_RS4_BE,
+ * EM_SPARC64, EM_PARISC,
+ * or EM_PPC are ABI compliant
+ */
+#define EM_MIPS_RS4_BE 10 /* MIPS R4000 Big-Endian */
+#define EM_SPARC64 11     /* SPARC v9 64-bit unofficial */
+#define EM_PARISC 15      /* HPPA */
+#define EM_SPARC32PLUS 18 /* Enhanced instruction set SPARC */
+#define EM_PPC 20         /* PowerPC */
+#define EM_PPC64 21       /* PowerPC 64 */
+#define EM_ARM 40         /* Advanced RISC Machines ARM */
+#define EM_ALPHA 41       /* DEC ALPHA */
+#define EM_SH 42          /* Hitachi/Renesas Super-H */
+#define EM_SPARCV9 43     /* SPARC version 9 */
+#define EM_IA_64 50       /* Intel IA-64 Processor */
+#define EM_AMD64 62       /* AMD64 architecture */
+#define EM_X86_64 EM_AMD64
+#define EM_VAX 75      /* DEC VAX */
+#define EM_AARCH64 183 /* ARM 64-bit architecture (AArch64) */
+
+/* Non-standard */
+#define EM_ALPHA_EXP 0x9026 /* DEC ALPHA */
+#define EM__LAST__ (EM_ALPHA_EXP + 1)
+
+#define EM_NUM 22 /* number of machine types */
+
+/* Version */
+#define EV_NONE 0    /* Invalid */
+#define EV_CURRENT 1 /* Current */
+#define EV_NUM 2     /* number of versions */
+
+/* Magic for e_phnum: get real value from sh_info of first section header */
+#define PN_XNUM 0xffff
+
+/* Section Header */
+typedef struct {
+    Elf32_Word sh_name;      /* name - index into section header
+					   string table section */
+    Elf32_Word sh_type;      /* type */
+    Elf32_Word sh_flags;     /* flags */
+    Elf32_Addr sh_addr;      /* address */
+    Elf32_Off sh_offset;     /* file offset */
+    Elf32_Word sh_size;      /* section size */
+    Elf32_Word sh_link;      /* section header table index link */
+    Elf32_Word sh_info;      /* extra information */
+    Elf32_Word sh_addralign; /* address alignment */
+    Elf32_Word sh_entsize;   /* section entry size */
+} Elf32_Shdr;
+
+typedef struct {
+    Elf64_Half sh_name;       /* section name */
+    Elf64_Half sh_type;       /* section type */
+    Elf64_Xword sh_flags;     /* section flags */
+    Elf64_Addr sh_addr;       /* virtual address */
+    Elf64_Off sh_offset;      /* file offset */
+    Elf64_Xword sh_size;      /* section size */
+    Elf64_Half sh_link;       /* link to another */
+    Elf64_Half sh_info;       /* misc info */
+    Elf64_Xword sh_addralign; /* memory alignment */
+    Elf64_Xword sh_entsize;   /* table entry size */
+} Elf64_Shdr;
+
+/* Special Section Indexes */
+#define SHN_UNDEF 0          /* undefined */
+#define SHN_LORESERVE 0xff00 /* lower bounds of reserved indexes */
+#define SHN_LOPROC 0xff00    /* reserved range for processor */
+#define SHN_HIPROC 0xff1f    /*   specific section indexes */
+#define SHN_ABS 0xfff1       /* absolute value */
+#define SHN_COMMON 0xfff2    /* common symbol */
+#define SHN_XINDEX 0xffff    /* Escape -- index stored elsewhere. */
+#define SHN_HIRESERVE 0xffff /* upper bounds of reserved indexes */
+
+/* sh_type */
+#define SHT_NULL 0                  /* inactive */
+#define SHT_PROGBITS 1              /* program defined information */
+#define SHT_SYMTAB 2                /* symbol table section */
+#define SHT_STRTAB 3                /* string table section */
+#define SHT_RELA 4                  /* relocation section with addends*/
+#define SHT_HASH 5                  /* symbol hash table section */
+#define SHT_DYNAMIC 6               /* dynamic section */
+#define SHT_NOTE 7                  /* note section */
+#define SHT_NOBITS 8                /* no space section */
+#define SHT_REL 9                   /* relation section without addends */
+#define SHT_SHLIB 10                /* reserved - purpose unknown */
+#define SHT_DYNSYM 11               /* dynamic symbol table section */
+#define SHT_NUM 12                  /* number of section types */
+#define SHT_INIT_ARRAY 14           /* pointers to init functions */
+#define SHT_FINI_ARRAY 15           /* pointers to termination functions */
+#define SHT_PREINIT_ARRAY 16        /* ptrs to funcs called before init */
+#define SHT_GROUP 17                /* defines a section group */
+#define SHT_SYMTAB_SHNDX 18         /* Section indexes (see SHN_XINDEX). */
+#define SHT_LOOS 0x60000000         /* reserved range for OS specific */
+#define SHT_SUNW_dof 0x6ffffff4     /* used by dtrace */
+#define SHT_GNU_LIBLIST 0x6ffffff7  /* libraries to be prelinked */
+#define SHT_SUNW_move 0x6ffffffa    /* inf for partially init'ed symbols */
+#define SHT_SUNW_syminfo 0x6ffffffc /* ad symbol information */
+#define SHT_SUNW_verdef 0x6ffffffd  /* symbol versioning inf */
+#define SHT_SUNW_verneed 0x6ffffffe /* symbol versioning req */
+#define SHT_SUNW_versym 0x6fffffff  /* symbol versioning table */
+#define SHT_HIOS 0x6fffffff         /*  section header types */
+#define SHT_LOPROC 0x70000000       /* reserved range for processor */
+#define SHT_HIPROC 0x7fffffff       /*  specific section header types */
+#define SHT_LOUSER 0x80000000       /* reserved range for application */
+#define SHT_HIUSER 0xffffffff       /*  specific indexes */
+
+#define SHT_GNU_HASH 0x6ffffff6 /* GNU-style hash table section */
+
+/* Section names */
+#define ELF_BSS ".bss"                              /* uninitialized data */
+#define ELF_DATA ".data"                            /* initialized data */
+#define ELF_CTF ".SUNW_ctf"                         /* CTF data */
+#define ELF_DEBUG ".debug"                          /* debug */
+#define ELF_DYNAMIC ".dynamic"                      /* dynamic linking information */
+#define ELF_DYNSTR ".dynstr"                        /* dynamic string table */
+#define ELF_DYNSYM ".dynsym"                        /* dynamic symbol table */
+#define ELF_FINI ".fini"                            /* termination code */
+#define ELF_GOT ".got"                              /* global offset table */
+#define ELF_HASH ".hash"                            /* symbol hash table */
+#define ELF_INIT ".init"                            /* initialization code */
+#define ELF_REL_DATA ".rel.data"                    /* relocation data */
+#define ELF_REL_FINI ".rel.fini"                    /* relocation termination code */
+#define ELF_REL_INIT ".rel.init"                    /* relocation initialization code */
+#define ELF_REL_DYN ".rel.dyn"                      /* relocation dynamic link info */
+#define ELF_REL_RODATA ".rel.rodata"                /* relocation read-only data */
+#define ELF_REL_TEXT ".rel.text"                    /* relocation code */
+#define ELF_RODATA ".rodata"                        /* read-only data */
+#define ELF_SHSTRTAB ".shstrtab"                    /* section header string table */
+#define ELF_STRTAB ".strtab"                        /* string table */
+#define ELF_SYMTAB ".symtab"                        /* symbol table */
+#define ELF_TEXT ".text"                            /* code */
+#define ELF_OPENBSDRANDOMDATA ".openbsd.randomdata" /* constant randomdata */
+
+/* Section Attribute Flags - sh_flags */
+#define SHF_WRITE 0x1              /* Writable */
+#define SHF_ALLOC 0x2              /* occupies memory */
+#define SHF_EXECINSTR 0x4          /* executable */
+#define SHF_MERGE 0x10             /* may be merged */
+#define SHF_STRINGS 0x20           /* contains strings */
+#define SHF_INFO_LINK 0x40         /* sh_info holds section index */
+#define SHF_LINK_ORDER 0x80        /* ordering requirements */
+#define SHF_OS_NONCONFORMING 0x100 /* OS-specific processing required */
+#define SHF_GROUP 0x200            /* member of section group */
+#define SHF_TLS 0x400              /* thread local storage */
+#define SHF_COMPRESSED 0x800       /* contains compressed data */
+#define SHF_MASKOS 0x0ff00000      /* OS-specific semantics */
+#define SHF_MASKPROC 0xf0000000    /* reserved bits for processor */
+                                   /*  specific section attributes */
+
+/* Symbol Table Entry */
+typedef struct elf32_sym {
+    Elf32_Word st_name;     /* name - index into string table */
+    Elf32_Addr st_value;    /* symbol value */
+    Elf32_Word st_size;     /* symbol size */
+    unsigned char st_info;  /* type and binding */
+    unsigned char st_other; /* 0 - no defined meaning */
+    Elf32_Half st_shndx;    /* section header index */
+} Elf32_Sym;
+
+typedef struct {
+    Elf64_Half st_name;     /* Symbol name index in str table */
+    Elf_Byte st_info;       /* type / binding attrs */
+    Elf_Byte st_other;      /* unused */
+    Elf64_Quarter st_shndx; /* section index of symbol */
+    Elf64_Xword st_value;   /* value of symbol */
+    Elf64_Xword st_size;    /* size of symbol */
+} Elf64_Sym;
+
+/* Symbol table index */
+#define STN_UNDEF 0 /* undefined */
+
+/* Extract symbol info - st_info */
+#define ELF32_ST_BIND(x) ((x) >> 4)
+#define ELF32_ST_TYPE(x) (((unsigned int)x) & 0xf)
+#define ELF32_ST_INFO(b, t) (((b) << 4) + ((t)&0xf))
+
+#define ELF64_ST_BIND(x) ((x) >> 4)
+#define ELF64_ST_TYPE(x) (((unsigned int)x) & 0xf)
+#define ELF64_ST_INFO(b, t) (((b) << 4) + ((t)&0xf))
+
+/* Symbol Binding - ELF32_ST_BIND - st_info */
+#define STB_LOCAL 0   /* Local symbol */
+#define STB_GLOBAL 1  /* Global symbol */
+#define STB_WEAK 2    /* like global - lower precedence */
+#define STB_NUM 3     /* number of symbol bindings */
+#define STB_LOPROC 13 /* reserved range for processor */
+#define STB_HIPROC 15 /*  specific symbol bindings */
+
+/* Symbol type - ELF32_ST_TYPE - st_info */
+#define STT_NOTYPE 0  /* not specified */
+#define STT_OBJECT 1  /* data object */
+#define STT_FUNC 2    /* function */
+#define STT_SECTION 3 /* section */
+#define STT_FILE 4    /* file */
+#define STT_TLS 6     /* thread local storage */
+#define STT_LOPROC 13 /* reserved range for processor */
+#define STT_HIPROC 15 /*  specific symbol types */
+
+/* Extract symbol visibility - st_other */
+#define ELF_ST_VISIBILITY(v) ((v)&0x3)
+#define ELF32_ST_VISIBILITY ELF_ST_VISIBILITY
+#define ELF64_ST_VISIBILITY ELF_ST_VISIBILITY
+
+#define STV_DEFAULT 0   /* Visibility set by binding type */
+#define STV_INTERNAL 1  /* OS specific version of STV_HIDDEN */
+#define STV_HIDDEN 2    /* can only be seen inside own .so */
+#define STV_PROTECTED 3 /* HIDDEN inside, DEFAULT outside */
+
+/* Relocation entry with implicit addend */
+typedef struct {
+    Elf32_Addr r_offset; /* offset of relocation */
+    Elf32_Word r_info;   /* symbol table index and type */
+} Elf32_Rel;
+
+/* Relocation entry with explicit addend */
+typedef struct {
+    Elf32_Addr r_offset; /* offset of relocation */
+    Elf32_Word r_info;   /* symbol table index and type */
+    Elf32_Sword r_addend;
+} Elf32_Rela;
+
+/* Extract relocation info - r_info */
+#define ELF32_R_SYM(i) ((i) >> 8)
+#define ELF32_R_TYPE(i) ((unsigned char)(i))
+#define ELF32_R_INFO(s, t) (((s) << 8) + (unsigned char)(t))
+
+typedef struct {
+    Elf64_Xword r_offset; /* where to do it */
+    Elf64_Xword r_info;   /* index & type of relocation */
+} Elf64_Rel;
+
+typedef struct {
+    Elf64_Xword r_offset;  /* where to do it */
+    Elf64_Xword r_info;    /* index & type of relocation */
+    Elf64_Sxword r_addend; /* adjustment value */
+} Elf64_Rela;
+
+#define ELF64_R_SYM(info) ((info) >> 32)
+#define ELF64_R_TYPE(info) ((info)&0xFFFFFFFF)
+#define ELF64_R_INFO(s, t) (((s) << 32) + (uint32_t)(t))
+
+#if defined(__mips64__) && defined(__MIPSEL__)
+/*
+ * The 64-bit MIPS ELF ABI uses a slightly different relocation format
+ * than the regular ELF ABI: the r_info field is split into several
+ * pieces (see gnu/usr.bin/binutils-2.17/include/elf/mips.h for details).
+ */
+#    undef ELF64_R_SYM
+#    undef ELF64_R_TYPE
+#    undef ELF64_R_INFO
+#    define ELF64_R_TYPE(info) ((uint64_t)swap32((info) >> 32))
+#    define ELF64_R_SYM(info) ((info)&0xFFFFFFFF)
+#    define ELF64_R_INFO(s, t) (((uint64_t)swap32(t) << 32) + (uint32_t)(s))
+#endif /* __mips64__ && __MIPSEL__ */
+
+/* Program Header */
+typedef struct {
+    Elf32_Word p_type;   /* segment type */
+    Elf32_Off p_offset;  /* segment offset */
+    Elf32_Addr p_vaddr;  /* virtual address of segment */
+    Elf32_Addr p_paddr;  /* physical address - ignored? */
+    Elf32_Word p_filesz; /* number of bytes in file for seg. */
+    Elf32_Word p_memsz;  /* number of bytes in mem. for seg. */
+    Elf32_Word p_flags;  /* flags */
+    Elf32_Word p_align;  /* memory alignment */
+} Elf32_Phdr;
+
+typedef struct {
+    Elf64_Half p_type;    /* entry type */
+    Elf64_Half p_flags;   /* flags */
+    Elf64_Off p_offset;   /* offset */
+    Elf64_Addr p_vaddr;   /* virtual address */
+    Elf64_Addr p_paddr;   /* physical address */
+    Elf64_Xword p_filesz; /* file size */
+    Elf64_Xword p_memsz;  /* memory size */
+    Elf64_Xword p_align;  /* memory & file alignment */
+} Elf64_Phdr;
+
+/* Segment types - p_type */
+#define PT_NULL 0            /* unused */
+#define PT_LOAD 1            /* loadable segment */
+#define PT_DYNAMIC 2         /* dynamic linking section */
+#define PT_INTERP 3          /* the RTLD */
+#define PT_NOTE 4            /* auxiliary information */
+#define PT_SHLIB 5           /* reserved - purpose undefined */
+#define PT_PHDR 6            /* program header */
+#define PT_TLS 7             /* thread local storage */
+#define PT_LOOS 0x60000000   /* reserved range for OS */
+#define PT_HIOS 0x6fffffff   /*  specific segment types */
+#define PT_LOPROC 0x70000000 /* reserved range for processor */
+#define PT_HIPROC 0x7fffffff /*  specific segment types */
+
+#define PT_GNU_EH_FRAME 0x6474e550 /* Exception handling info */
+#define PT_GNU_RELRO 0x6474e552    /* Read-only after relocation */
+#define PT_GNU_STACK 0x6474e551    /* Stack permissions info */
+
+#define PT_OPENBSD_RANDOMIZE 0x65a3dbe6 /* fill with random data */
+#define PT_OPENBSD_WXNEEDED 0x65a3dbe7  /* program performs W^X violations */
+#define PT_OPENBSD_BOOTDATA 0x65a41be6  /* section for boot arguments */
+
+/* Segment flags - p_flags */
+#define PF_X 0x1               /* Executable */
+#define PF_W 0x2               /* Writable */
+#define PF_R 0x4               /* Readable */
+#define PF_MASKPROC 0xf0000000 /* reserved bits for processor */
+                               /*  specific segment flags */
+
+/* Dynamic structure */
+typedef struct {
+    Elf32_Sword d_tag; /* controls meaning of d_val */
+    union {
+        Elf32_Word d_val; /* Multiple meanings - see d_tag */
+        Elf32_Addr d_ptr; /* program virtual address */
+    } d_un;
+} Elf32_Dyn;
+
+typedef struct {
+    Elf64_Xword d_tag; /* controls meaning of d_val */
+    union {
+        Elf64_Addr d_ptr;
+        Elf64_Xword d_val;
+    } d_un;
+} Elf64_Dyn;
+
+/* Dynamic Array Tags - d_tag */
+#define DT_NULL 0             /* marks end of _DYNAMIC array */
+#define DT_NEEDED 1           /* string table offset of needed lib */
+#define DT_PLTRELSZ 2         /* size of relocation entries in PLT */
+#define DT_PLTGOT 3           /* address PLT/GOT */
+#define DT_HASH 4             /* address of symbol hash table */
+#define DT_STRTAB 5           /* address of string table */
+#define DT_SYMTAB 6           /* address of symbol table */
+#define DT_RELA 7             /* address of relocation table */
+#define DT_RELASZ 8           /* size of relocation table */
+#define DT_RELAENT 9          /* size of relocation entry */
+#define DT_STRSZ 10           /* size of string table */
+#define DT_SYMENT 11          /* size of symbol table entry */
+#define DT_INIT 12            /* address of initialization func. */
+#define DT_FINI 13            /* address of termination function */
+#define DT_SONAME 14          /* string table offset of shared obj */
+#define DT_RPATH 15           /* string table offset of library \
+                                 search path */
+#define DT_SYMBOLIC 16        /* start sym search in shared obj. */
+#define DT_REL 17             /* address of rel. tbl. w addends */
+#define DT_RELSZ 18           /* size of DT_REL relocation table */
+#define DT_RELENT 19          /* size of DT_REL relocation entry */
+#define DT_PLTREL 20          /* PLT referenced relocation entry */
+#define DT_DEBUG 21           /* bugger */
+#define DT_TEXTREL 22         /* Allow rel. mod. to unwritable seg */
+#define DT_JMPREL 23          /* add. of PLT's relocation entries */
+#define DT_BIND_NOW 24        /* Bind now regardless of env setting */
+#define DT_INIT_ARRAY 25      /* address of array of init func */
+#define DT_FINI_ARRAY 26      /* address of array of term func */
+#define DT_INIT_ARRAYSZ 27    /* size of array of init func */
+#define DT_FINI_ARRAYSZ 28    /* size of array of term func */
+#define DT_RUNPATH 29         /* strtab offset of lib search path */
+#define DT_FLAGS 30           /* Set of DF_* flags */
+#define DT_ENCODING 31        /* further DT_* follow encoding rules */
+#define DT_PREINIT_ARRAY 32   /* address of array of preinit func */
+#define DT_PREINIT_ARRAYSZ 33 /* size of array of preinit func */
+#define DT_LOOS 0x6000000d    /* reserved range for OS */
+#define DT_HIOS 0x6ffff000    /*  specific dynamic array tags */
+#define DT_LOPROC 0x70000000  /* reserved range for processor */
+#define DT_HIPROC 0x7fffffff  /*  specific dynamic array tags */
+
+/* some other useful tags */
+#define DT_GNU_HASH 0x6ffffef5  /* address of GNU hash table */
+#define DT_RELACOUNT 0x6ffffff9 /* if present, number of RELATIVE */
+#define DT_RELCOUNT 0x6ffffffa  /* relocs, which must come first */
+#define DT_FLAGS_1 0x6ffffffb
+
+/* Dynamic Flags - DT_FLAGS .dynamic entry */
+#define DF_ORIGIN 0x00000001
+#define DF_SYMBOLIC 0x00000002
+#define DF_TEXTREL 0x00000004
+#define DF_BIND_NOW 0x00000008
+#define DF_STATIC_TLS 0x00000010
+
+/* Dynamic Flags - DT_FLAGS_1 .dynamic entry */
+#define DF_1_NOW 0x00000001
+#define DF_1_GLOBAL 0x00000002
+#define DF_1_GROUP 0x00000004
+#define DF_1_NODELETE 0x00000008
+#define DF_1_LOADFLTR 0x00000010
+#define DF_1_INITFIRST 0x00000020
+#define DF_1_NOOPEN 0x00000040
+#define DF_1_ORIGIN 0x00000080
+#define DF_1_DIRECT 0x00000100
+#define DF_1_TRANS 0x00000200
+#define DF_1_INTERPOSE 0x00000400
+#define DF_1_NODEFLIB 0x00000800
+#define DF_1_NODUMP 0x00001000
+#define DF_1_CONLFAT 0x00002000
+
+/*
+ * Note header
+ */
+typedef struct {
+    Elf32_Word n_namesz;
+    Elf32_Word n_descsz;
+    Elf32_Word n_type;
+} Elf32_Nhdr;
+
+typedef struct {
+    Elf64_Half n_namesz;
+    Elf64_Half n_descsz;
+    Elf64_Half n_type;
+} Elf64_Nhdr;
+
+/*
+ * Note Definitions
+ */
+typedef struct {
+    Elf32_Word namesz;
+    Elf32_Word descsz;
+    Elf32_Word type;
+} Elf32_Note;
+
+typedef struct {
+    Elf64_Half namesz;
+    Elf64_Half descsz;
+    Elf64_Half type;
+} Elf64_Note;
+
+/* Values for n_type. */
+#define NT_PRSTATUS 1 /* Process status. */
+#define NT_FPREGSET 2 /* Floating point registers. */
+#define NT_PRPSINFO 3 /* Process state info. */
+
+/*
+ * OpenBSD-specific core file information.
+ *
+ * OpenBSD ELF core files use notes to provide information about
+ * the process's state.  The note name is "OpenBSD" for information
+ * that is global to the process, and "OpenBSD@nn", where "nn" is the
+ * thread ID of the thread that the information belongs to (such as
+ * register state).
+ *
+ * We use the following note identifiers:
+ *
+ *	NT_OPENBSD_PROCINFO
+ *		Note is a "elfcore_procinfo" structure.
+ *	NT_OPENBSD_AUXV
+ *		Note is a a bunch of Auxiliary Vectors, terminated by
+ *		an AT_NULL entry.
+ *	NT_OPENBSD_REGS
+ *		Note is a "reg" structure.
+ *	NT_OPENBSD_FPREGS
+ *		Note is a "fpreg" structure.
+ *
+ * Please try to keep the members of the "elfcore_procinfo" structure
+ * nicely aligned, and if you add elements, add them to the end and
+ * bump the version.
+ */
+
+#define NT_OPENBSD_PROCINFO 10
+#define NT_OPENBSD_AUXV 11
+
+#define NT_OPENBSD_REGS 20
+#define NT_OPENBSD_FPREGS 21
+#define NT_OPENBSD_XFPREGS 22
+#define NT_OPENBSD_WCOOKIE 23
+
+struct elfcore_procinfo {
+    /* Version 1 fields start here. */
+    uint32_t cpi_version; /* netbsd_elfcore_procinfo version */
+#define ELFCORE_PROCINFO_VERSION 1
+    uint32_t cpi_cpisize;   /* sizeof(netbsd_elfcore_procinfo) */
+    uint32_t cpi_signo;     /* killing signal */
+    uint32_t cpi_sigcode;   /* signal code */
+    uint32_t cpi_sigpend;   /* pending signals */
+    uint32_t cpi_sigmask;   /* blocked signals */
+    uint32_t cpi_sigignore; /* ignored signals */
+    uint32_t cpi_sigcatch;  /* signals being caught by user */
+    int32_t cpi_pid;        /* process ID */
+    int32_t cpi_ppid;       /* parent process ID */
+    int32_t cpi_pgrp;       /* process group ID */
+    int32_t cpi_sid;        /* session ID */
+    uint32_t cpi_ruid;      /* real user ID */
+    uint32_t cpi_euid;      /* effective user ID */
+    uint32_t cpi_svuid;     /* saved user ID */
+    uint32_t cpi_rgid;      /* real group ID */
+    uint32_t cpi_egid;      /* effective group ID */
+    uint32_t cpi_svgid;     /* saved group ID */
+    int8_t cpi_name[32];    /* copy of pr->ps_comm */
+};
+
+/*
+ * XXX - these _KERNEL items aren't part of the ABI!
+ */
+#if defined(_KERNEL) || defined(_DYN_LOADER)
+
+#    define ELF32_NO_ADDR ((uint32_t)~0) /* Indicates addr. not yet filled in */
+
+typedef struct {
+    Elf32_Sword au_id; /* 32-bit id */
+    Elf32_Word au_v;   /* 32-bit value */
+} Aux32Info;
+
+#    define ELF64_NO_ADDR ((uint64_t)~0) /* Indicates addr. not yet filled in */
+
+typedef struct {
+    Elf64_Shalf au_id; /* 32-bit id */
+    Elf64_Xword au_v;  /* 64-bit value */
+} Aux64Info;
+
+enum AuxID {
+    AUX_null = 0,
+    AUX_ignore = 1,
+    AUX_execfd = 2,
+    AUX_phdr = 3,        /* &phdr[0] */
+    AUX_phent = 4,       /* sizeof(phdr[0]) */
+    AUX_phnum = 5,       /* # phdr entries */
+    AUX_pagesz = 6,      /* PAGESIZE */
+    AUX_base = 7,        /* ld.so base addr */
+    AUX_flags = 8,       /* processor flags */
+    AUX_entry = 9,       /* a.out entry */
+    AUX_sun_uid = 2000,  /* euid */
+    AUX_sun_ruid = 2001, /* ruid */
+    AUX_sun_gid = 2002,  /* egid */
+    AUX_sun_rgid = 2003  /* rgid */
+};
+
+struct elf_args {
+    u_long arg_entry;     /* program entry point */
+    u_long arg_interp;    /* Interpreter load address */
+    u_long arg_phaddr;    /* program header address */
+    u_long arg_phentsize; /* Gfx::Size of program header */
+    u_long arg_phnum;     /* Number of program headers */
+};
+
+#endif
+
+#if !defined(ELFSIZE) && defined(ARCH_ELFSIZE)
+#    define ELFSIZE ARCH_ELFSIZE
+#endif
+
+#if defined(ELFSIZE)
+#    define CONCAT(x, y) __CONCAT(x, y)
+#    define ELFNAME(x) CONCAT(elf, CONCAT(ELFSIZE, CONCAT(_, x)))
+#    define ELFDEFNNAME(x) CONCAT(ELF, CONCAT(ELFSIZE, CONCAT(_, x)))
+#endif
+
+#if defined(ELFSIZE) && (ELFSIZE == 32)
+#    define Elf_Ehdr Elf32_Ehdr
+#    define Elf_Phdr Elf32_Phdr
+#    define Elf_Shdr Elf32_Shdr
+#    define Elf_Sym Elf32_Sym
+#    define Elf_Rel Elf32_Rel
+#    define Elf_RelA Elf32_Rela
+#    define Elf_Dyn Elf32_Dyn
+#    define Elf_Half Elf32_Half
+#    define Elf_Word Elf32_Word
+#    define Elf_Sword Elf32_Sword
+#    define Elf_Addr Elf32_Addr
+#    define Elf_Off Elf32_Off
+#    define Elf_Nhdr Elf32_Nhdr
+#    define Elf_Note Elf32_Note
+
+#    define ELF_R_SYM ELF32_R_SYM
+#    define ELF_R_TYPE ELF32_R_TYPE
+#    define ELF_R_INFO ELF32_R_INFO
+#    define ELFCLASS ELFCLASS32
+
+#    define ELF_ST_BIND ELF32_ST_BIND
+#    define ELF_ST_TYPE ELF32_ST_TYPE
+#    define ELF_ST_INFO ELF32_ST_INFO
+
+#    define ELF_NO_ADDR ELF32_NO_ADDR
+#    define AuxInfo Aux32Info
+#elif defined(ELFSIZE) && (ELFSIZE == 64)
+#    define Elf_Ehdr Elf64_Ehdr
+#    define Elf_Phdr Elf64_Phdr
+#    define Elf_Shdr Elf64_Shdr
+#    define Elf_Sym Elf64_Sym
+#    define Elf_Rel Elf64_Rel
+#    define Elf_RelA Elf64_Rela
+#    define Elf_Dyn Elf64_Dyn
+#    define Elf_Half Elf64_Half
+#    define Elf_Word Elf64_Word
+#    define Elf_Sword Elf64_Sword
+#    define Elf_Addr Elf64_Addr
+#    define Elf_Off Elf64_Off
+#    define Elf_Nhdr Elf64_Nhdr
+#    define Elf_Note Elf64_Note
+
+#    define ELF_R_SYM ELF64_R_SYM
+#    define ELF_R_TYPE ELF64_R_TYPE
+#    define ELF_R_INFO ELF64_R_INFO
+#    define ELFCLASS ELFCLASS64
+
+#    define ELF_ST_BIND ELF64_ST_BIND
+#    define ELF_ST_TYPE ELF64_ST_TYPE
+#    define ELF_ST_INFO ELF64_ST_INFO
+
+#    define ELF_NO_ADDR ELF64_NO_ADDR
+#    define AuxInfo Aux64Info
+#endif
+
+#define ELF_TARG_VER 1 /* The ver for which this code is intended */
+
+/* Relocation types */
+#define R_386_NONE 0
+#define R_386_32 1         /* Symbol + Addend */
+#define R_386_PC32 2       /* Symbol + Addend - Section offset */
+#define R_386_GOT32 3      /* Used by build-time linker to create GOT entry */
+#define R_386_PLT32 4      /* Used by build-time linker to create PLT entry */
+#define R_386_COPY 5       /* https://docs.oracle.com/cd/E23824_01/html/819-0690/chapter4-10454.html#chapter4-84604 */
+#define R_386_GLOB_DAT 6   /* Relation b/w GOT entry and symbol */
+#define R_386_JMP_SLOT 7   /* Fixed up by dynamic loader */
+#define R_386_RELATIVE 8   /* Base address + Addned */
+#define R_386_TLS_TPOFF 14 /* Negative offset into the static TLS storage */
+#define R_386_TLS_TPOFF32 37
+
+#endif /* _SYS_EXEC_ELF_H_ */