mirror of
https://sourceware.org/git/glibc.git
synced 2025-04-20 12:27:47 +03:00
0ca8785a28
If some shared library loaded with dlopen/dlmopen requires an executable stack, either implicitly because of a missing GNU_STACK ELF header (where the ABI default flags implies in the executable bit) or explicitly because of the executable bit from GNU_STACK; the loader will try to set the both the main thread and all thread stacks (from the pthread cache) as executable. Besides the issue where any __nptl_change_stack_perm failure does not undo the previous executable transition (meaning that if the library fails to load, there can be thread stacks with executable stacks), this behavior was used on a CVE [1] as a vector for RCE. This patch changes that if a shared library requires an executable stack, and the current stack is not executable, dlopen fails. The change is done only for dynamically loaded modules, if the program or any dependency requires an executable stack, the loader will still change the main thread before program execution and any thread created with default stack configuration. [1] https://www.qualys.com/2023/07/19/cve-2023-38408/rce-openssh-forwarded-ssh-agent.txt Checked on x86_64-linux-gnu and i686-linux-gnu. Reviewed-by: Florian Weimer <fweimer@redhat.com>
46 lines
1.4 KiB
C
46 lines
1.4 KiB
C
/* Stack executability handling for GNU dynamic linker. Linux version.
|
|
Copyright (C) 2003-2024 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
|
|
The GNU C Library is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU Lesser General Public
|
|
License as published by the Free Software Foundation; either
|
|
version 2.1 of the License, or (at your option) any later version.
|
|
|
|
The GNU C Library is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public
|
|
License along with the GNU C Library; if not, see
|
|
<https://www.gnu.org/licenses/>. */
|
|
|
|
#include <ldsodefs.h>
|
|
|
|
int
|
|
_dl_make_stack_executable (void **stack_endp)
|
|
{
|
|
/* This gives us the highest/lowest page that needs to be changed. */
|
|
uintptr_t page = ((uintptr_t) *stack_endp
|
|
& -(intptr_t) GLRO(dl_pagesize));
|
|
|
|
if (__mprotect ((void *) page, GLRO(dl_pagesize),
|
|
PROT_READ | PROT_WRITE | PROT_EXEC
|
|
#if _STACK_GROWS_DOWN
|
|
| PROT_GROWSDOWN
|
|
#elif _STACK_GROWS_UP
|
|
| PROT_GROWSUP
|
|
#endif
|
|
) != 0)
|
|
return errno;
|
|
|
|
/* Clear the address. */
|
|
*stack_endp = NULL;
|
|
|
|
/* Remember that we changed the permission. */
|
|
GL(dl_stack_flags) |= PF_X;
|
|
|
|
return 0;
|
|
}
|