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7edd3814b0
The __stack_prot is used by Linux to make the stack executable if a modules requires it. It is also marked as RELRO, which requires to change the segment permission to RW to update it. Also, there is no need to keep track of the flags: either the stack will have the default permission of the ABI or should be change to PROT_READ | PROT_WRITE | PROT_EXEC. The only additional flag, PROT_GROWSDOWN or PROT_GROWSUP, is Linux only and can be deducted from _STACK_GROWS_DOWN/_STACK_GROWS_UP. Also, the check_consistency function was already removed some time ago. Checked on x86_64-linux-gnu and i686-linux-gnu. Reviewed-by: Florian Weimer <fweimer@redhat.com>
108 lines
2.9 KiB
C
108 lines
2.9 KiB
C
/* Stack executability handling for GNU dynamic linker. Linux version.
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Copyright (C) 2003-2024 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <errno.h>
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#include <ldsodefs.h>
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#include <libintl.h>
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#include <list.h>
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#include <pthreadP.h>
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#include <stackinfo.h>
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#include <stdbool.h>
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#include <sys/mman.h>
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#include <sysdep.h>
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#include <unistd.h>
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static int
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make_main_stack_executable (void **stack_endp)
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{
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/* This gives us the highest/lowest page that needs to be changed. */
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uintptr_t page = ((uintptr_t) *stack_endp
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& -(intptr_t) GLRO(dl_pagesize));
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if (__mprotect ((void *) page, GLRO(dl_pagesize),
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PROT_READ | PROT_WRITE | PROT_EXEC
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#if _STACK_GROWS_DOWN
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| PROT_GROWSDOWN
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#elif _STACK_GROWS_UP
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| PROT_GROWSUP
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#endif
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) != 0)
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return errno;
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/* Clear the address. */
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*stack_endp = NULL;
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/* Remember that we changed the permission. */
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GL(dl_stack_flags) |= PF_X;
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return 0;
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}
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int
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_dl_make_stacks_executable (void **stack_endp)
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{
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/* First the main thread's stack. */
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int err = make_main_stack_executable (stack_endp);
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if (err != 0)
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return err;
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lll_lock (GL (dl_stack_cache_lock), LLL_PRIVATE);
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list_t *runp;
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list_for_each (runp, &GL (dl_stack_used))
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{
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err = __nptl_change_stack_perm (list_entry (runp, struct pthread, list));
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if (err != 0)
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break;
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}
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/* Also change the permission for the currently unused stacks. This
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might be wasted time but better spend it here than adding a check
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in the fast path. */
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if (err == 0)
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list_for_each (runp, &GL (dl_stack_cache))
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{
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err = __nptl_change_stack_perm (list_entry (runp, struct pthread,
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list));
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if (err != 0)
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break;
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}
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lll_unlock (GL (dl_stack_cache_lock), LLL_PRIVATE);
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return err;
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}
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int
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__nptl_change_stack_perm (struct pthread *pd)
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{
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#if _STACK_GROWS_DOWN
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void *stack = pd->stackblock + pd->guardsize;
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size_t len = pd->stackblock_size - pd->guardsize;
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#elif _STACK_GROWS_UP
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void *stack = pd->stackblock;
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size_t len = (uintptr_t) pd - pd->guardsize - (uintptr_t) pd->stackblock;
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#else
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# error "Define either _STACK_GROWS_DOWN or _STACK_GROWS_UP"
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#endif
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if (__mprotect (stack, len, PROT_READ | PROT_WRITE | PROT_EXEC) != 0)
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return errno;
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return 0;
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}
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rtld_hidden_def (__nptl_change_stack_perm)
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