mirror of
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187 lines
4.8 KiB
C
187 lines
4.8 KiB
C
/* Stack protector support.
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Copyright (C) 2005-2013 Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 3, or (at your option) any later
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version.
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In addition to the permissions in the GNU General Public License, the
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Free Software Foundation gives you unlimited permission to link the
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compiled version of this file into combinations with other programs,
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and to distribute those combinations without any restriction coming
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from the use of this file. (The General Public License restrictions
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do apply in other respects; for example, they cover modification of
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the file, and distribution when not linked into a combine
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executable.)
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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Under Section 7 of GPL version 3, you are granted additional
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permissions described in the GCC Runtime Library Exception, version
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3.1, as published by the Free Software Foundation.
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You should have received a copy of the GNU General Public License and
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a copy of the GCC Runtime Library Exception along with this program;
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see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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<http://www.gnu.org/licenses/>. */
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#include "config.h"
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#ifdef HAVE_ALLOCA_H
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# include <alloca.h>
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#endif
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#ifdef HAVE_MALLOC_H
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# include <malloc.h>
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#endif
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#ifdef HAVE_STRING_H
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# include <string.h>
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#endif
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#ifdef HAVE_UNISTD_H
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# include <unistd.h>
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#endif
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#ifdef HAVE_FCNTL_H
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# include <fcntl.h>
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#endif
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#ifdef HAVE_PATHS_H
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# include <paths.h>
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#endif
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#ifndef _PATH_TTY
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/* Native win32 apps don't know about /dev/tty but can print directly
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to the console using "CONOUT$" */
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#if defined (_WIN32) && !defined (__CYGWIN__)
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# define _PATH_TTY "CONOUT$"
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#else
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# define _PATH_TTY "/dev/tty"
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#endif
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#endif
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#ifdef HAVE_SYSLOG_H
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# include <syslog.h>
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#endif
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void *__stack_chk_guard = 0;
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static void __attribute__ ((constructor))
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__guard_setup (void)
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{
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unsigned char *p;
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int fd;
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if (__stack_chk_guard != 0)
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return;
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fd = open ("/dev/urandom", O_RDONLY);
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if (fd != -1)
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{
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ssize_t size = read (fd, &__stack_chk_guard,
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sizeof (__stack_chk_guard));
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close (fd);
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if (size == sizeof(__stack_chk_guard) && __stack_chk_guard != 0)
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return;
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}
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/* If a random generator can't be used, the protector switches the guard
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to the "terminator canary". */
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p = (unsigned char *) &__stack_chk_guard;
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p[sizeof(__stack_chk_guard)-1] = 255;
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p[sizeof(__stack_chk_guard)-2] = '\n';
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p[0] = 0;
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}
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static void
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fail (const char *msg1, size_t msg1len, const char *msg3)
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{
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#ifdef __GNU_LIBRARY__
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extern char * __progname;
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#else
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static const char __progname[] = "";
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#endif
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int fd;
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/* Print error message directly to the tty. This avoids Bad Things
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happening if stderr is redirected. */
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fd = open (_PATH_TTY, O_WRONLY);
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if (fd != -1)
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{
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static const char msg2[] = " terminated\n";
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size_t progname_len, len;
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char *buf, *p;
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progname_len = strlen (__progname);
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len = msg1len + progname_len + sizeof(msg2)-1 + 1;
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p = buf = alloca (len);
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memcpy (p, msg1, msg1len);
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p += msg1len;
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memcpy (p, __progname, progname_len);
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p += progname_len;
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memcpy (p, msg2, sizeof(msg2));
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while (len > 0)
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{
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ssize_t wrote = write (fd, buf, len);
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if (wrote < 0)
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break;
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buf += wrote;
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len -= wrote;
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}
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close (fd);
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}
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#ifdef HAVE_SYSLOG_H
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/* Only send the error to syslog if there was no tty available. */
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else
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syslog (LOG_CRIT, "%s", msg3);
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#endif /* HAVE_SYSLOG_H */
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/* Try very hard to exit. Note that signals may be blocked preventing
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the first two options from working. The use of volatile is here to
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prevent optimizers from "knowing" that __builtin_trap is called first,
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and that it doesn't return, and so "obviously" the rest of the code
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is dead. */
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{
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volatile int state;
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for (state = 0; ; state++)
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switch (state)
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{
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case 0:
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__builtin_trap ();
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break;
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case 1:
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*(volatile int *)-1L = 0;
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break;
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case 2:
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_exit (127);
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break;
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}
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}
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}
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void
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__stack_chk_fail (void)
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{
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const char *msg = "*** stack smashing detected ***: ";
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fail (msg, strlen (msg), "stack smashing detected: terminated");
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}
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void
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__chk_fail (void)
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{
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const char *msg = "*** buffer overflow detected ***: ";
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fail (msg, strlen (msg), "buffer overflow detected: terminated");
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}
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#ifdef HAVE_HIDDEN_VISIBILITY
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void
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__attribute__((visibility ("hidden")))
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__stack_chk_fail_local (void)
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{
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__stack_chk_fail ();
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}
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#endif
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