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ed6a68bac7
The 7bb8045ec0 path made the '%n' fortify check ignore EMFILE errors
while trying to open /proc/self/maps, and this added a security
issue where EMFILE can be attacker-controlled thus making it
ineffective for some cases.
The EMFILE failure is reinstated but with a different error
message. Also, to improve the false positive of the hardening for
the cases where no new files can be opened, the
_dl_readonly_area now uses _dl_find_object to check if the
memory area is within a writable ELF segment. The procfs method is
still used as fallback.
Checked on x86_64-linux-gnu and i686-linux-gnu.
Reviewed-by: Arjun Shankar <arjun@redhat.com>
54 lines
1.7 KiB
C
54 lines
1.7 KiB
C
/* Test if a memory region is wholly unwritable. Mach version.
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Copyright (C) 2004-2025 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 <stdlib.h>
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#include <stdint.h>
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#include <mach.h>
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enum readonly_error_type
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__readonly_area_fallback (const void *ptr, size_t size)
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{
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vm_address_t region_address = (uintptr_t) ptr;
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vm_size_t region_length = size;
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vm_prot_t protection;
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vm_prot_t max_protection;
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vm_inherit_t inheritance;
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boolean_t is_shared;
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mach_port_t object_name;
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vm_offset_t offset;
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while (__vm_region (__mach_task_self (),
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®ion_address, ®ion_length,
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&protection, &max_protection, &inheritance, &is_shared,
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&object_name, &offset) == KERN_SUCCESS
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&& region_address <= (uintptr_t) ptr)
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{
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region_address += region_length;
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if (region_address < (uintptr_t) ptr)
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continue;
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if (protection & VM_PROT_WRITE)
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return readonly_area_writable;
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if (region_address - (uintptr_t) ptr >= size)
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break;
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}
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return readonly_noerror;
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}
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