120 lines
3.3 KiB
C
120 lines
3.3 KiB
C
/* Stack executability handling for GNU dynamic linker. Linux version.
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Copyright (C) 2003-2022 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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extern int __stack_prot attribute_relro attribute_hidden;
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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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int result = 0;
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if (__builtin_expect (__mprotect ((void *) page, GLRO(dl_pagesize),
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__stack_prot) == 0, 1))
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goto return_success;
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result = errno;
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goto out;
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return_success:
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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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out:
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#ifdef check_consistency
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check_consistency ();
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#endif
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return result;
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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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#ifdef NEED_SEPARATE_REGISTER_STACK
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size_t pagemask = __getpagesize () - 1;
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void *stack = (pd->stackblock
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+ (((((pd->stackblock_size - pd->guardsize) / 2)
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& pagemask) + pd->guardsize) & pagemask));
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size_t len = pd->stackblock + pd->stackblock_size - stack;
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#elif _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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