glibc/sysdeps/aarch64/linkmap.h
Szabolcs Nagy cd543b5eb3 aarch64: Use mmap to add PROT_BTI instead of mprotect [BZ #26831]
Re-mmap executable segments if possible instead of using mprotect
to add PROT_BTI. This allows using BTI protection with security
policies that prevent mprotect with PROT_EXEC.

If the fd of the ELF module is not available because it was kernel
mapped then mprotect is used and failures are ignored.  To protect
the main executable even when mprotect is filtered the linux kernel
 will have to be changed to add PROT_BTI to it.

The delayed failure reporting is mainly needed because currently
_dl_process_gnu_properties does not propagate failures such that
the required cleanups happen. Using the link_map_machine struct for
error propagation is not ideal, but this seemed to be the least
intrusive solution.

Fixes bug 26831.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
2020-12-11 15:46:02 +00:00

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1.0 KiB
C

/* Copyright (C) 2009-2020 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 <stdbool.h>
struct link_map_machine
{
ElfW(Addr) plt; /* Address of .plt */
void *tlsdesc_table; /* Address of TLS descriptor hash table. */
bool bti_fail; /* Failed to enable Branch Target Identification. */
};