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glibc/sysdeps/mach/hurd/dl-execstack.c
Cupertino Miranda 3b2b88ccee elf: early conversion of elf p_flags to mprotect flags
This patch replaces _dl_stack_flags global variable by
_dl_stack_prot_flags.
The advantage is that any convertion from p_flags to final used mprotect
flags occurs at loading of p_flags. It avoids repeated spurious
convertions of _dl_stack_flags, for example in allocate_thread_stack.

This modification was suggested in:
  https://sourceware.org/pipermail/libc-alpha/2025-March/165537.html

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
2025-08-27 10:45:45 -03:00

49 lines
1.6 KiB
C

/* Stack executability handling for GNU dynamic linker. Hurd version.
Copyright (C) 2004-2025 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>
#include <hurdstartup.h>
#include <errno.h>
extern struct hurd_startup_data *_dl_hurd_data attribute_hidden;
/* There is no portable way to know the bounds of the initial thread's stack
so as to mprotect it. */
int
_dl_make_stack_executable (const void *stack_endp)
{
/* Challenge the caller. */
if (__glibc_unlikely (stack_endp != __libc_stack_end))
return EPERM;
#if IS_IN (rtld)
if (__mprotect ((void *)_dl_hurd_data->stack_base, _dl_hurd_data->stack_size,
PROT_READ|PROT_WRITE|PROT_EXEC) != 0)
return errno;
/* Remember that we changed the permission. */
GL(dl_stack_prot_flags) |= PROT_EXEC;
return 0;
#else
/* We don't bother to implement this for static linking. */
return ENOSYS;
#endif
}