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Kernel: Disallow syscalls from writeable memory

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Processes will now crash with SIGSEGV if they attempt making a syscall
from PROT_WRITE memory.

This neat idea comes from OpenBSD. :^)
This commit is contained in:
Andreas Kling 2019-11-29 16:15:30 +01:00
parent ea52fe528a
commit e56daf547c
5 changed files with 27 additions and 5 deletions
Download patch file Download diff file Expand all files Collapse all files

13
Kernel/Syscall.cpp
View file

@ -105,6 +105,19 @@ void syscall_trap_entry(RegisterDump regs)
ASSERT_NOT_REACHED();
}
auto* calling_region = MM.region_from_vaddr(process, VirtualAddress(regs.eip));
if (!calling_region) {
dbgprintf("Syscall from %p which has no region\n", regs.eip);
handle_crash(regs, "Syscall from unknown region", SIGSEGV);
ASSERT_NOT_REACHED();
}
if (calling_region->is_writable()) {
dbgprintf("Syscall from writable memory at %p\n", regs.eip);
handle_crash(regs, "Syscall from writable memory", SIGSEGV);
ASSERT_NOT_REACHED();
}
process.big_lock().lock();
u32 function = regs.eax;
u32 arg1 = regs.edx;

1
Kernel/VM/MemoryManager.cpp
View file

@ -289,7 +289,6 @@ Region* MemoryManager::user_region_from_vaddr(Process& process, VirtualAddress v
Region* MemoryManager::region_from_vaddr(Process& process, VirtualAddress vaddr)
{
ASSERT_INTERRUPTS_DISABLED();
if (auto* region = kernel_region_from_vaddr(vaddr))
return region;
return user_region_from_vaddr(process, vaddr);

8
Kernel/VM/MemoryManager.h
View file

@ -1,6 +1,5 @@
#pragma once
#include <AK/String.h>
#include <AK/Badge.h>
#include <AK/Bitmap.h>
#include <AK/ByteBuffer.h>
@ -8,6 +7,7 @@
#include <AK/NonnullRefPtrVector.h>
#include <AK/RefCounted.h>
#include <AK/RefPtr.h>
#include <AK/String.h>
#include <AK/Types.h>
#include <AK/Vector.h>
#include <AK/Weakable.h>
@ -79,6 +79,9 @@ public:
}
}
static Region* region_from_vaddr(Process&, VirtualAddress);
static const Region* region_from_vaddr(const Process&, VirtualAddress);
private:
MemoryManager(u32 physical_address_for_kernel_page_tables);
~MemoryManager();
@ -96,9 +99,6 @@ private:
void create_identity_mapping(PageDirectory&, VirtualAddress, size_t length);
static Region* region_from_vaddr(Process&, VirtualAddress);
static const Region* region_from_vaddr(const Process&, VirtualAddress);
static Region* user_region_from_vaddr(Process&, VirtualAddress);
static Region* kernel_region_from_vaddr(VirtualAddress);