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Diffstat (limited to 'libssp/ssp.c')
| -rw-r--r-- | libssp/ssp.c | 186 |
1 files changed, 186 insertions, 0 deletions
diff --git a/libssp/ssp.c b/libssp/ssp.c new file mode 100644 index 000000000..aaa5a322c --- /dev/null +++ b/libssp/ssp.c @@ -0,0 +1,186 @@ +/* Stack protector support. + Copyright (C) 2005, 2009 Free Software Foundation, Inc. + +This file is part of GCC. + +GCC is free software; you can redistribute it and/or modify it under +the terms of the GNU General Public License as published by the Free +Software Foundation; either version 3, or (at your option) any later +version. + +In addition to the permissions in the GNU General Public License, the +Free Software Foundation gives you unlimited permission to link the +compiled version of this file into combinations with other programs, +and to distribute those combinations without any restriction coming +from the use of this file. (The General Public License restrictions +do apply in other respects; for example, they cover modification of +the file, and distribution when not linked into a combine +executable.) + +GCC 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 General Public License +for more details. + +Under Section 7 of GPL version 3, you are granted additional +permissions described in the GCC Runtime Library Exception, version +3.1, as published by the Free Software Foundation. + +You should have received a copy of the GNU General Public License and +a copy of the GCC Runtime Library Exception along with this program; +see the files COPYING3 and COPYING.RUNTIME respectively. If not, see +<http://www.gnu.org/licenses/>. */ + + +#include "config.h" +#ifdef HAVE_ALLOCA_H +# include <alloca.h> +#endif +#ifdef HAVE_MALLOC_H +# include <malloc.h> +#endif +#ifdef HAVE_STRING_H +# include <string.h> +#endif +#ifdef HAVE_UNISTD_H +# include <unistd.h> +#endif +#ifdef HAVE_FCNTL_H +# include <fcntl.h> +#endif +#ifdef HAVE_PATHS_H +# include <paths.h> +#endif +#ifndef _PATH_TTY +/* Native win32 apps don't know about /dev/tty but can print directly + to the console using "CONOUT$" */ +#if defined (_WIN32) && !defined (__CYGWIN__) +# define _PATH_TTY "CONOUT$" +#else +# define _PATH_TTY "/dev/tty" +#endif +#endif +#ifdef HAVE_SYSLOG_H +# include <syslog.h> +#endif + +void *__stack_chk_guard = 0; + +static void __attribute__ ((constructor)) +__guard_setup (void) +{ + unsigned char *p; + int fd; + + if (__stack_chk_guard != 0) + return; + + fd = open ("/dev/urandom", O_RDONLY); + if (fd != -1) + { + ssize_t size = read (fd, &__stack_chk_guard, + sizeof (__stack_chk_guard)); + close (fd); + if (size == sizeof(__stack_chk_guard) && __stack_chk_guard != 0) + return; + } + + /* If a random generator can't be used, the protector switches the guard + to the "terminator canary". */ + p = (unsigned char *) &__stack_chk_guard; + p[sizeof(__stack_chk_guard)-1] = 255; + p[sizeof(__stack_chk_guard)-2] = '\n'; + p[0] = 0; +} + +static void +fail (const char *msg1, size_t msg1len, const char *msg3) +{ +#ifdef __GNU_LIBRARY__ + extern char * __progname; +#else + static const char __progname[] = ""; +#endif + int fd; + + /* Print error message directly to the tty. This avoids Bad Things + happening if stderr is redirected. */ + fd = open (_PATH_TTY, O_WRONLY); + if (fd != -1) + { + static const char msg2[] = " terminated\n"; + size_t progname_len, len; + char *buf, *p; + + progname_len = strlen (__progname); + len = msg1len + progname_len + sizeof(msg2)-1 + 1; + p = buf = alloca (len); + + memcpy (p, msg1, msg1len); + p += msg1len; + memcpy (p, __progname, progname_len); + p += progname_len; + memcpy (p, msg2, sizeof(msg2)); + + while (len > 0) + { + ssize_t wrote = write (fd, buf, len); + if (wrote < 0) + break; + buf += wrote; + len -= wrote; + } + close (fd); + } + +#ifdef HAVE_SYSLOG_H + /* Only send the error to syslog if there was no tty available. */ + else + syslog (LOG_CRIT, msg3); +#endif /* HAVE_SYSLOG_H */ + + /* Try very hard to exit. Note that signals may be blocked preventing + the first two options from working. The use of volatile is here to + prevent optimizers from "knowing" that __builtin_trap is called first, + and that it doesn't return, and so "obviously" the rest of the code + is dead. */ + { + volatile int state; + for (state = 0; ; state++) + switch (state) + { + case 0: + __builtin_trap (); + break; + case 1: + *(volatile int *)-1L = 0; + break; + case 2: + _exit (127); + break; + } + } +} + +void +__stack_chk_fail (void) +{ + const char *msg = "*** stack smashing detected ***: "; + fail (msg, strlen (msg), "stack smashing detected: terminated"); +} + +void +__chk_fail (void) +{ + const char *msg = "*** buffer overflow detected ***: "; + fail (msg, strlen (msg), "buffer overflow detected: terminated"); +} + +#ifdef HAVE_HIDDEN_VISIBILITY +void +__attribute__((visibility ("hidden"))) +__stack_chk_fail_local (void) +{ + __stack_chk_fail (); +} +#endif |