From 88f4b6929c26f9240a4b0b7dcc62922f02544a09 Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Tue, 18 Oct 2022 17:00:07 +0200 Subject: Introduce , extracted from 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 dependency in the C code by using the computed constant from . no longer includes these definitions, so there is no cyclic dependency anymore when computing the constants. Reviewed-by: Adhemerval Zanella --- sysdeps/unix/sysv/linux/i386/pointer_guard.h | 49 ++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+) create mode 100644 sysdeps/unix/sysv/linux/i386/pointer_guard.h (limited to 'sysdeps/unix/sysv/linux/i386/pointer_guard.h') diff --git a/sysdeps/unix/sysv/linux/i386/pointer_guard.h b/sysdeps/unix/sysv/linux/i386/pointer_guard.h new file mode 100644 index 0000000000..a2d2a0c38b --- /dev/null +++ b/sysdeps/unix/sysv/linux/i386/pointer_guard.h @@ -0,0 +1,49 @@ +/* Pointer obfuscation implenentation. i386 version. + Copyright (C) 2005-2022 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 + . */ + +#ifndef POINTER_GUARD_H +#define POINTER_GUARD_H + +#include + +#if IS_IN (rtld) +/* We cannot use the thread descriptor because in ld.so we use setjmp + earlier than the descriptor is initialized. Using a global variable + is too complicated here since we have no PC-relative addressing mode. */ +# include +#else +# ifdef __ASSEMBLER__ +# define PTR_MANGLE(reg) xorl %gs:POINTER_GUARD, reg; \ + roll $9, reg +# define PTR_DEMANGLE(reg) rorl $9, reg; \ + xorl %gs:POINTER_GUARD, reg +# else +# define PTR_MANGLE(var) asm ("xorl %%gs:%c2, %0\n" \ + "roll $9, %0" \ + : "=r" (var) \ + : "0" (var), \ + "i" (POINTER_GUARD)) +# define PTR_DEMANGLE(var) asm ("rorl $9, %0\n" \ + "xorl %%gs:%c2, %0" \ + : "=r" (var) \ + : "0" (var), \ + "i" (POINTER_GUARD)) +# endif +#endif + +#endif /* POINTER_GUARD_H */ -- cgit v1.2.3-70-g09d2