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Kernel: Add "prot_exec" pledge promise and require it for PROT_EXEC

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This prevents sys$mmap() and sys$mprotect() from creating executable
memory mappings in pledged programs that don't have this promise.

Note that the dynamic loader runs before pledging happens, so it's
unaffected by this.
This commit is contained in:
Andreas Kling 2021-01-29 18:50:27 +01:00
parent df30b3e54c
commit d0c5979d96
Notes: sideshowbarker 2024-07-18 22:46:07 +09:00 
Author: https://github.com/awesomekling
Commit: https://github.com/SerenityOS/serenity/commit/d0c5979d96f
3 changed files with 11 additions and 1 deletions
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1
Base/usr/share/man/man2/pledge.md
View file

@ -53,6 +53,7 @@ If the process later attempts to use any system functionality it has previously
* `sendfd`: Send file descriptors over a local socket
* `recvfd`: Receive file descriptors over a local socket
* `ptrace`: The [`ptrace(2)`](ptrace.md) syscall (\*)
* `prot_exec`: [`mmap(2)`](mmap.md) and [`mprotect(2)`](mprotect.md) with `PROT_EXEC` (\*)
Promises marked with an asterisk (\*) are SerenityOS specific extensions not supported by the original OpenBSD `pledge()`.

3
Kernel/Process.h
View file

@ -81,7 +81,8 @@ extern VirtualAddress g_return_to_ring3_from_signal_trampoline;
__ENUMERATE_PLEDGE_PROMISE(accept) \
__ENUMERATE_PLEDGE_PROMISE(settime) \
__ENUMERATE_PLEDGE_PROMISE(sigaction) \
__ENUMERATE_PLEDGE_PROMISE(setkeymap)
__ENUMERATE_PLEDGE_PROMISE(setkeymap) \
__ENUMERATE_PLEDGE_PROMISE(prot_exec)
enum class Pledge : u32 {
#define __ENUMERATE_PLEDGE_PROMISE(x) x,

8
Kernel/Syscalls/mmap.cpp
View file

@ -163,6 +163,10 @@ void* Process::sys$mmap(Userspace<const Syscall::SC_mmap_params*> user_params)
int fd = params.fd;
int offset = params.offset;
if (prot & PROT_EXEC) {
REQUIRE_PROMISE(prot_exec);
}
if (alignment & ~PAGE_MASK)
return (void*)-EINVAL;
@ -274,6 +278,10 @@ int Process::sys$mprotect(void* addr, size_t size, int prot)
{
REQUIRE_PROMISE(stdio);
if (prot & PROT_EXEC) {
REQUIRE_PROMISE(prot_exec);
}
if (!size)
return -EINVAL;