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88f4b6929c
This allows us to define a generic no-op version of PTR_MANGLE and PTR_DEMANGLE. In the future, we can use PTR_MANGLE and PTR_DEMANGLE unconditionally in C sources, avoiding an unintended loss of hardening due to missing include files or unlucky header inclusion ordering. In i386 and x86_64, we can avoid a <tls.h> dependency in the C code by using the computed constant from <tcb-offsets.h>. <sysdep.h> no longer includes these definitions, so there is no cyclic dependency anymore when computing the <tcb-offsets.h> constants. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
68 lines
2.8 KiB
C
68 lines
2.8 KiB
C
/* Pointer guard implementation. Arm version.
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Copyright (C) 2013-2022 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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#ifndef POINTER_GUARD_H
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#define POINTER_GUARD_H
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/* Pointer mangling support. */
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#if (IS_IN (rtld) \
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|| (!defined SHARED && (IS_IN (libc) || IS_IN (libpthread))))
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# ifdef __ASSEMBLER__
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# define PTR_MANGLE_LOAD(guard, tmp) \
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LDR_HIDDEN (guard, tmp, C_SYMBOL_NAME(__pointer_chk_guard_local), 0)
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# define PTR_MANGLE(dst, src, guard, tmp) \
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PTR_MANGLE_LOAD(guard, tmp); \
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PTR_MANGLE2(dst, src, guard)
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/* Use PTR_MANGLE2 for efficiency if guard is already loaded. */
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# define PTR_MANGLE2(dst, src, guard) \
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eor dst, src, guard
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# define PTR_DEMANGLE(dst, src, guard, tmp) \
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PTR_MANGLE (dst, src, guard, tmp)
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# define PTR_DEMANGLE2(dst, src, guard) \
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PTR_MANGLE2 (dst, src, guard)
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# else
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extern uintptr_t __pointer_chk_guard_local attribute_relro attribute_hidden;
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# define PTR_MANGLE(var) \
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(var) = (__typeof (var)) ((uintptr_t) (var) ^ __pointer_chk_guard_local)
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# define PTR_DEMANGLE(var) PTR_MANGLE (var)
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# endif
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#else
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# ifdef __ASSEMBLER__
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# define PTR_MANGLE_LOAD(guard, tmp) \
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LDR_GLOBAL (guard, tmp, C_SYMBOL_NAME(__pointer_chk_guard), 0);
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# define PTR_MANGLE(dst, src, guard, tmp) \
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PTR_MANGLE_LOAD(guard, tmp); \
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PTR_MANGLE2(dst, src, guard)
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/* Use PTR_MANGLE2 for efficiency if guard is already loaded. */
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# define PTR_MANGLE2(dst, src, guard) \
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eor dst, src, guard
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# define PTR_DEMANGLE(dst, src, guard, tmp) \
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PTR_MANGLE (dst, src, guard, tmp)
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# define PTR_DEMANGLE2(dst, src, guard) \
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PTR_MANGLE2 (dst, src, guard)
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# else
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# include <stdint.h>
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extern uintptr_t __pointer_chk_guard attribute_relro;
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# define PTR_MANGLE(var) \
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(var) = (__typeof (var)) ((uintptr_t) (var) ^ __pointer_chk_guard)
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# define PTR_DEMANGLE(var) PTR_MANGLE (var)
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# endif
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#endif
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#endif /* POINTER_GUARD_H */
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