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/* Copyright (C) 2004-2014 Free Software Foundation, Inc.
Copyright (C) 2006-2014 Gentoo 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, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
/* Hardened Gentoo SSP and FORTIFY handler
A failure handler that does not use functions from the rest of glibc;
it uses the INTERNAL_SYSCALL methods directly. This helps ensure no
possibility of recursion into the handler.
Direct all bug reports to http://bugs.gentoo.org/
People who have contributed significantly to the evolution of this file:
Ned Ludd - <solar[@]gentoo.org>
Alexander Gabert - <pappy[@]gentoo.org>
The PaX Team - <pageexec[@]freemail.hu>
Peter S. Mazinger - <ps.m[@]gmx.net>
Yoann Vandoorselaere - <yoann[@]prelude-ids.org>
Robert Connolly - <robert[@]linuxfromscratch.org>
Cory Visi <cory[@]visi.name>
Mike Frysinger <vapier[@]gentoo.org>
Magnus Granberg <zorry[@]gentoo.org>
Kevin F. Quinn - <kevquinn[@]gentoo.org>
*/
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>
#include <sysdep-cancel.h>
#include <sys/syscall.h>
#include <kernel-features.h>
#include <alloca.h>
/* from sysdeps */
#include <socketcall.h>
/* for the stuff in bits/socket.h */
#include <sys/socket.h>
#include <sys/un.h>
/* Sanity check on SYSCALL macro names - force compilation
* failure if the names used here do not exist
*/
#if !defined __NR_socketcall && !defined __NR_socket
# error Cannot do syscall socket or socketcall
#endif
#if !defined __NR_socketcall && !defined __NR_connect
# error Cannot do syscall connect or socketcall
#endif
#ifndef __NR_write
# error Cannot do syscall write
#endif
#ifndef __NR_close
# error Cannot do syscall close
#endif
#ifndef __NR_getpid
# error Cannot do syscall getpid
#endif
#ifndef __NR_kill
# error Cannot do syscall kill
#endif
#ifndef __NR_exit
# error Cannot do syscall exit
#endif
#ifdef SSP_SMASH_DUMPS_CORE
# define ENABLE_SSP_SMASH_DUMPS_CORE 1
# if !defined _KERNEL_NSIG && !defined _NSIG
# error No _NSIG or _KERNEL_NSIG for rt_sigaction
# endif
# if !defined __NR_sigaction && !defined __NR_rt_sigaction
# error Cannot do syscall sigaction or rt_sigaction
# endif
/* Although rt_sigaction expects sizeof(sigset_t) - it expects the size
* of the _kernel_ sigset_t which is not the same as the user sigset_t.
* Most arches have this as _NSIG bits - mips has _KERNEL_NSIG bits for
* some reason.
*/
# ifdef _KERNEL_NSIG
# define _SSP_NSIG _KERNEL_NSIG
# else
# define _SSP_NSIG _NSIG
# endif
#else
# define _SSP_NSIG 0
# define ENABLE_SSP_SMASH_DUMPS_CORE 0
#endif
/* Define DO_SIGACTION - default to newer rt signal interface but
* fallback to old as needed.
*/
#ifdef __NR_rt_sigaction
# define DO_SIGACTION(signum, act, oldact) \
INLINE_SYSCALL(rt_sigaction, 4, signum, act, oldact, _SSP_NSIG/8)
#else
# define DO_SIGACTION(signum, act, oldact) \
INLINE_SYSCALL(sigaction, 3, signum, act, oldact)
#endif
/* Define DO_SOCKET/DO_CONNECT functions to deal with socketcall vs socket/connect */
#if defined(__NR_socket) && defined(__NR_connect)
# define USE_OLD_SOCKETCALL 0
#else
# define USE_OLD_SOCKETCALL 1
#endif
/* stub out the __NR_'s so we can let gcc optimize away dead code */
#ifndef __NR_socketcall
# define __NR_socketcall 0
#endif
#ifndef __NR_socket
# define __NR_socket 0
#endif
#ifndef __NR_connect
# define __NR_connect 0
#endif
#define DO_SOCKET(result, domain, type, protocol) \
do { \
if (USE_OLD_SOCKETCALL) { \
socketargs[0] = domain; \
socketargs[1] = type; \
socketargs[2] = protocol; \
socketargs[3] = 0; \
result = INLINE_SYSCALL(socketcall, 2, SOCKOP_socket, socketargs); \
} else \
result = INLINE_SYSCALL(socket, 3, domain, type, protocol); \
} while (0)
#define DO_CONNECT(result, sockfd, serv_addr, addrlen) \
do { \
if (USE_OLD_SOCKETCALL) { \
socketargs[0] = sockfd; \
socketargs[1] = (unsigned long int)serv_addr; \
socketargs[2] = addrlen; \
socketargs[3] = 0; \
result = INLINE_SYSCALL(socketcall, 2, SOCKOP_connect, socketargs); \
} else \
result = INLINE_SYSCALL(connect, 3, sockfd, serv_addr, addrlen); \
} while (0)
#ifndef _PATH_LOG
# define _PATH_LOG "/dev/log"
#endif
static const char path_log[] = _PATH_LOG;
/* For building glibc with SSP switched on, define __progname to a
* constant if building for the run-time loader, to avoid pulling
* in more of libc.so into ld.so
*/
#ifdef IS_IN_rtld
static const char *__progname = "<ldso>";
#else
extern const char *__progname;
#endif
#ifdef GENTOO_SSP_HANDLER
# define ERROR_MSG "stack smashing"
#else
# define ERROR_MSG "buffer overflow"
#endif
/* Common handler code, used by chk_fail
* Inlined to ensure no self-references to the handler within itself.
* Data static to avoid putting more than necessary on the stack,
* to aid core debugging.
*/
__attribute__ ((__noreturn__, __always_inline__))
static inline void
__hardened_gentoo_fail(void)
{
#define MESSAGE_BUFSIZ 512
static pid_t pid;
static int plen, i, hlen;
static char message[MESSAGE_BUFSIZ];
/* <11> is LOG_USER|LOG_ERR. A dummy date for loggers to skip over. */
static const char msg_header[] = "<11>" __DATE__ " " __TIME__ " glibc-gentoo-hardened-check: ";
static const char msg_ssd[] = "*** " ERROR_MSG " detected ***: ";
static const char msg_terminated[] = " terminated; ";
static const char msg_report[] = "report to " REPORT_BUGS_TO "\n";
static const char msg_unknown[] = "<unknown>";
static int log_socket, connect_result;
static struct sockaddr_un sock;
static unsigned long int socketargs[4];
/* Build socket address */
sock.sun_family = AF_UNIX;
i = 0;
while (path_log[i] != '\0' && i < sizeof(sock.sun_path) - 1) {
sock.sun_path[i] = path_log[i];
++i;
}
sock.sun_path[i] = '\0';
/* Try SOCK_DGRAM connection to syslog */
connect_result = -1;
DO_SOCKET(log_socket, AF_UNIX, SOCK_DGRAM, 0);
if (log_socket != -1)
DO_CONNECT(connect_result, log_socket, &sock, sizeof(sock));
if (connect_result == -1) {
if (log_socket != -1)
INLINE_SYSCALL(close, 1, log_socket);
/* Try SOCK_STREAM connection to syslog */
DO_SOCKET(log_socket, AF_UNIX, SOCK_STREAM, 0);
if (log_socket != -1)
DO_CONNECT(connect_result, log_socket, &sock, sizeof(sock));
}
/* Build message. Messages are generated both in the old style and new style,
* so that log watchers that are configured for the old-style message continue
* to work.
*/
#define strconcat(str) \
({ \
i = 0; \
while ((str[i] != '\0') && ((i + plen) < (MESSAGE_BUFSIZ - 1))) { \
message[plen + i] = str[i]; \
++i; \
} \
plen += i; \
})
/* Tersely log the failure */
plen = 0;
strconcat(msg_header);
hlen = plen;
strconcat(msg_ssd);
if (__progname != NULL)
strconcat(__progname);
else
strconcat(msg_unknown);
strconcat(msg_terminated);
strconcat(msg_report);
/* Write out error message to STDERR, to syslog if open */
INLINE_SYSCALL(write, 3, STDERR_FILENO, message + hlen, plen - hlen);
if (connect_result != -1) {
INLINE_SYSCALL(write, 3, log_socket, message, plen);
INLINE_SYSCALL(close, 1, log_socket);
}
/* Time to kill self since we have no idea what is going on */
pid = INLINE_SYSCALL(getpid, 0);
if (ENABLE_SSP_SMASH_DUMPS_CORE) {
/* Remove any user-supplied handler for SIGABRT, before using it. */
#if 0
/*
* Note: Disabled because some programs catch & process their
* own crashes. We've already enabled this code path which
* means we want to let core dumps happen.
*/
static struct sigaction default_abort_act;
default_abort_act.sa_handler = SIG_DFL;
default_abort_act.sa_sigaction = NULL;
__sigfillset(&default_abort_act.sa_mask);
default_abort_act.sa_flags = 0;
if (DO_SIGACTION(SIGABRT, &default_abort_act, NULL) == 0)
#endif
INLINE_SYSCALL(kill, 2, pid, SIGABRT);
}
/* SIGKILL is only signal which cannot be caught */
INLINE_SYSCALL(kill, 2, pid, SIGKILL);
/* In case the kill didn't work, exit anyway.
* The loop prevents gcc thinking this routine returns.
*/
while (1)
INLINE_SYSCALL(exit, 1, 137);
}
__attribute__ ((__noreturn__))
#ifdef GENTOO_SSP_HANDLER
void __stack_chk_fail(void)
#else
void __chk_fail(void)
#endif
{
__hardened_gentoo_fail();
}
#ifdef GENTOO_SSP_HANDLER
strong_alias (__stack_chk_fail, __stack_chk_fail_local)
#endif
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