diff options
Diffstat (limited to 'sysdeps/unix/sysv/linux/x86_64/allocate-shadow-stack.c')
-rw-r--r-- | sysdeps/unix/sysv/linux/x86_64/allocate-shadow-stack.c | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/x86_64/allocate-shadow-stack.c b/sysdeps/unix/sysv/linux/x86_64/allocate-shadow-stack.c new file mode 100644 index 0000000000..f2e1d03b96 --- /dev/null +++ b/sysdeps/unix/sysv/linux/x86_64/allocate-shadow-stack.c @@ -0,0 +1,55 @@ +/* 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 +} |