From e5ebdb9bca3588b2fb01891127771b03dae09ad9 Mon Sep 17 00:00:00 2001 From: Itamar Date: Sat, 28 Mar 2020 11:57:46 +0300 Subject: [PATCH] strace: Change implementation to use ptrace() --- Libraries/LibC/Makefile | 1 + Libraries/LibC/sys/ptrace.cpp | 44 +++++++++++++ Libraries/LibC/sys/ptrace.h | 42 ++++++++++++ Libraries/LibC/unistd.cpp | 6 -- Libraries/LibC/unistd.h | 1 - Userland/strace.cpp | 121 +++++++++++++++++++++++++--------- 6 files changed, 177 insertions(+), 38 deletions(-) create mode 100644 Libraries/LibC/sys/ptrace.cpp create mode 100644 Libraries/LibC/sys/ptrace.h diff --git a/Libraries/LibC/Makefile b/Libraries/LibC/Makefile index ece0689caf..6705d05475 100644 --- a/Libraries/LibC/Makefile +++ b/Libraries/LibC/Makefile @@ -46,6 +46,7 @@ LIBC_OBJS = \ sys/socket.o \ sys/wait.o \ sys/uio.o \ + sys/ptrace.o \ poll.o \ locale.o \ arpa/inet.o \ diff --git a/Libraries/LibC/sys/ptrace.cpp b/Libraries/LibC/sys/ptrace.cpp new file mode 100644 index 0000000000..b9c0c16234 --- /dev/null +++ b/Libraries/LibC/sys/ptrace.cpp @@ -0,0 +1,44 @@ +/* + * Copyright (c) 2020, Itamar S. + * 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 +#include +#include + +extern "C" { + +int ptrace(int request, pid_t pid, void* addr, int data) +{ + Syscall::SC_ptrace_params params { + request, + pid, + reinterpret_cast(addr), + data + }; + int rc = syscall(SC_ptrace, ¶ms); + __RETURN_WITH_ERRNO(rc, rc, -1); +} +} diff --git a/Libraries/LibC/sys/ptrace.h b/Libraries/LibC/sys/ptrace.h new file mode 100644 index 0000000000..9f385d4787 --- /dev/null +++ b/Libraries/LibC/sys/ptrace.h @@ -0,0 +1,42 @@ +/* + * Copyright (c) 2020, Itamar S. + * 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 + +__BEGIN_DECLS + +#define PT_TRACE_ME 1 +#define PT_ATTACH 2 +#define PT_CONTINUE 3 +#define PT_SYSCALL 4 +#define PT_GETREGS 5 +#define PT_DETACH 6 + +int ptrace(int request, pid_t pid, void* addr, int data); + +__END_DECLS diff --git a/Libraries/LibC/unistd.cpp b/Libraries/LibC/unistd.cpp index d9a1dcd6c8..cd17c7ae83 100644 --- a/Libraries/LibC/unistd.cpp +++ b/Libraries/LibC/unistd.cpp @@ -45,12 +45,6 @@ extern "C" { -int systrace(pid_t pid) -{ - int rc = syscall(SC_systrace, pid); - __RETURN_WITH_ERRNO(rc, rc, -1); -} - int chown(const char* pathname, uid_t uid, gid_t gid) { if (!pathname) { diff --git a/Libraries/LibC/unistd.h b/Libraries/LibC/unistd.h index c13829f437..2566abfdfd 100644 --- a/Libraries/LibC/unistd.h +++ b/Libraries/LibC/unistd.h @@ -58,7 +58,6 @@ int get_process_name(char* buffer, int buffer_size); void dump_backtrace(); int fsync(int fd); void sysbeep(); -int systrace(pid_t); int gettid(); int donate(int tid); int set_process_icon(int icon_id); diff --git a/Userland/strace.cpp b/Userland/strace.cpp index 1b51318a16..30d7bad9b7 100644 --- a/Userland/strace.cpp +++ b/Userland/strace.cpp @@ -25,18 +25,34 @@ */ #include +#include #include #include +#include #include #include #include #include +#include +#include #include static int usage() { - printf("usage: strace [-p PID] [command...]\n"); - return 0; + printf("usage: strace [-p pid] [command...]\n"); + return 1; +} + +static int g_pid = -1; + +static void handle_sigint(int) +{ + if (g_pid == -1) + return; + + if (ptrace(PT_DETACH, g_pid, 0, 0) == -1) { + perror("detach"); + } } int main(int argc, char** argv) @@ -44,18 +60,17 @@ int main(int argc, char** argv) if (argc == 1) return usage(); - pid_t pid = -1; - bool pid_is_child = false; - if (!strcmp(argv[1], "-p")) { if (argc != 3) return usage(); - pid = atoi(argv[2]); + g_pid = atoi(argv[2]); } else { - pid_is_child = true; - pid = fork(); + int pid = fork(); if (!pid) { - kill(getpid(), SIGSTOP); + if (ptrace(PT_TRACE_ME, 0, 0, 0) == -1) { + perror("traceme"); + return 1; + } int rc = execvp(argv[1], &argv[1]); if (rc < 0) { perror("execvp"); @@ -63,40 +78,84 @@ int main(int argc, char** argv) } ASSERT_NOT_REACHED(); } + if (waitpid(pid, nullptr, WSTOPPED) != pid) { + perror("waitpid"); + return 1; + } + g_pid = pid; } - int fd = systrace(pid); - if (fd < 0) { - perror("systrace"); + struct sigaction sa; + memset(&sa, 0, sizeof(struct sigaction)); + sa.sa_handler = handle_sigint; + sigaction(SIGINT, &sa, nullptr); + + if (ptrace(PT_ATTACH, g_pid, 0, 0) == -1) { + perror("attach"); return 1; } - if (pid_is_child) { - int rc = kill(pid, SIGCONT); - if (rc < 0) { - perror("kill(pid, SIGCONT)"); - return 1; - } + if (waitpid(g_pid, nullptr, WSTOPPED) != g_pid) { + perror("waitpid"); + return 1; } for (;;) { - u32 call[5]; - int nread = read(fd, &call, sizeof(call)); - if (nread == 0) - break; - if (nread < 0) { - perror("read"); + if (ptrace(PT_SYSCALL, g_pid, 0, 0) == -1) { + if (errno == ESRCH) + return 0; + perror("syscall"); + return 1; + } + if (waitpid(g_pid, nullptr, WSTOPPED) != g_pid) { + perror("wait_pid"); return 1; } - ASSERT(nread == sizeof(call)); - fprintf(stderr, "%s(%#x, %#x, %#x) = %#x\n", Syscall::to_string((Syscall::Function)call[0]), call[1], call[2], call[3], call[4]); - } - int rc = close(fd); - if (rc < 0) { - perror("close"); - return 1; + PtraceRegisters regs = {}; + if (ptrace(PT_GETREGS, g_pid, ®s, 0) == -1) { + perror("getregs"); + return 1; + } + + u32 syscall_index = regs.eax; + u32 arg1 = regs.edx; + u32 arg2 = regs.ecx; + u32 arg3 = regs.ebx; + + // skip syscall exit + if (ptrace(PT_SYSCALL, g_pid, 0, 0) == -1) { + if (errno == ESRCH) + return 0; + perror("syscall"); + return 1; + } + if (waitpid(g_pid, nullptr, WSTOPPED) != g_pid) { + perror("wait_pid"); + return 1; + } + + if (ptrace(PT_GETREGS, g_pid, ®s, 0) == -1) { + if (errno == ESRCH && syscall_index == SC_exit) { + regs.eax = 0; + } else { + perror("getregs"); + return 1; + } + } + + u32 res = regs.eax; + + fprintf(stderr, "%s(0x%x, 0x%x, 0x%x)\t=%d\n", + Syscall::to_string( + (Syscall::Function)syscall_index), + arg1, + arg2, + arg3, + res); } return 0; + + return 0; }