mirror of
git://sourceware.org/git/glibc.git
synced 2025-03-06 20:58:33 +01:00
edb5e0c8f9
Sync with Linux kernel 6.6 shadow stack interface. Since only x86-64 is supported, i386 shadow stack codes are unchanged and CET shouldn't be enabled for i386. 1. When the shadow stack base in TCB is unset, the default shadow stack is in use. Use the current shadow stack pointer as the marker for the default shadow stack. It is used to identify if the current shadow stack is the same as the target shadow stack when switching ucontexts. If yes, INCSSP will be used to unwind shadow stack. Otherwise, shadow stack restore token will be used. 2. Allocate shadow stack with the map_shadow_stack syscall. Since there is no function to explicitly release ucontext, there is no place to release shadow stack allocated by map_shadow_stack in ucontext functions. Such shadow stacks will be leaked. 3. Rename arch_prctl CET commands to ARCH_SHSTK_XXX. 4. Rewrite the CET control functions with the current kernel shadow stack interface. Since CET is no longer enabled by kernel, a separate patch will enable shadow stack during startup.
55 lines
1.9 KiB
C
55 lines
1.9 KiB
C
/* Helper function to allocate shadow stack.
|
|
Copyright (C) 2023 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 <sysdep.h>
|
|
#include <stdint.h>
|
|
#include <errno.h>
|
|
#include <sys/mman.h>
|
|
#include <libc-pointer-arith.h>
|
|
#include <allocate-shadow-stack.h>
|
|
|
|
/* NB: This can be treated as a syscall by caller. */
|
|
|
|
long int
|
|
__allocate_shadow_stack (size_t stack_size,
|
|
shadow_stack_size_t *child_stack)
|
|
{
|
|
#ifdef __NR_map_shadow_stack
|
|
size_t shadow_stack_size
|
|
= stack_size >> STACK_SIZE_TO_SHADOW_STACK_SIZE_SHIFT;
|
|
/* Align shadow stack to 8 bytes. */
|
|
shadow_stack_size = ALIGN_UP (shadow_stack_size, 8);
|
|
/* Since sigaltstack shares shadow stack with the current context in
|
|
the thread, add extra 20 stack frames in shadow stack for signal
|
|
handlers. */
|
|
shadow_stack_size += 20 * 8;
|
|
void *shadow_stack = (void *)INLINE_SYSCALL_CALL
|
|
(map_shadow_stack, NULL, shadow_stack_size, SHADOW_STACK_SET_TOKEN);
|
|
/* Report the map_shadow_stack error. */
|
|
if (shadow_stack == MAP_FAILED)
|
|
return -errno;
|
|
|
|
/* Save the shadow stack base and size on child stack. */
|
|
child_stack[0] = (uintptr_t) shadow_stack;
|
|
child_stack[1] = shadow_stack_size;
|
|
|
|
return 0;
|
|
#else
|
|
return -ENOSYS;
|
|
#endif
|
|
}
|