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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>
50 lines
2.3 KiB
C
50 lines
2.3 KiB
C
/* Pointer obfuscation implenentation. i386 version.
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Copyright (C) 2005-2022 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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#include <tcb-offsets.h>
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#if IS_IN (rtld)
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/* We cannot use the thread descriptor because in ld.so we use setjmp
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earlier than the descriptor is initialized. Using a global variable
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is too complicated here since we have no PC-relative addressing mode. */
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# include <sysdeps/generic/pointer_guard.h>
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#else
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# ifdef __ASSEMBLER__
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# define PTR_MANGLE(reg) xorl %gs:POINTER_GUARD, reg; \
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roll $9, reg
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# define PTR_DEMANGLE(reg) rorl $9, reg; \
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xorl %gs:POINTER_GUARD, reg
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# else
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# define PTR_MANGLE(var) asm ("xorl %%gs:%c2, %0\n" \
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"roll $9, %0" \
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: "=r" (var) \
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: "0" (var), \
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"i" (POINTER_GUARD))
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# define PTR_DEMANGLE(var) asm ("rorl $9, %0\n" \
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"xorl %%gs:%c2, %0" \
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: "=r" (var) \
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: "0" (var), \
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"i" (POINTER_GUARD))
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# endif
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#endif
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#endif /* POINTER_GUARD_H */
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