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/* Copyright (C) 2005 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, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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/* Copyright (C) 2006-2007 Gentoo Foundation Inc.
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* License terms as above.
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*
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* Hardened Gentoo SSP handler
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*
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* An SSP failure handler that does not use functions from the rest of
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* glibc; it uses the INTERNAL_SYSCALL methods directly. This ensures
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* no possibility of recursion into the handler.
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*
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* Direct all bug reports to http://bugs.gentoo.org/
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*
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* Re-written from the glibc-2.3 Hardened Gentoo SSP handler
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* by Kevin F. Quinn - <kevquinn[@]gentoo.org>
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*
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* The following people contributed to the glibc-2.3 Hardened
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* Gentoo SSP handler, from which this implementation draws much:
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*
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* Ned Ludd - <solar[@]gentoo.org>
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* Alexander Gabert - <pappy[@]gentoo.org>
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* The PaX Team - <pageexec[@]freemail.hu>
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* Peter S. Mazinger - <ps.m[@]gmx.net>
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* Yoann Vandoorselaere - <yoann[@]prelude-ids.org>
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* Robert Connolly - <robert[@]linuxfromscratch.org>
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* Cory Visi <cory[@]visi.name>
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* Mike Frysinger <vapier[@]gentoo.org>
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*/
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#include <errno.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <signal.h>
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#include <sys/types.h>
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#include <sysdep-cancel.h>
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#include <sys/syscall.h>
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#include <bp-checks.h>
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#include <kernel-features.h>
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#include <alloca.h>
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/* from sysdeps */
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#include <socketcall.h>
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/* for the stuff in bits/socket.h */
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#include <sys/socket.h>
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#include <sys/un.h>
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/* Sanity check on SYSCALL macro names - force compilation
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* failure if the names used here do not exist
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*/
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#if !defined __NR_socketcall && !defined __NR_socket
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# error Cannot do syscall socket or socketcall
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#endif
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#if !defined __NR_socketcall && !defined __NR_connect
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# error Cannot do syscall connect or socketcall
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#endif
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#ifndef __NR_write
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# error Cannot do syscall write
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#endif
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#ifndef __NR_close
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# error Cannot do syscall close
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#endif
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#ifndef __NR_getpid
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# error Cannot do syscall getpid
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#endif
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#ifndef __NR_kill
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# error Cannot do syscall kill
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#endif
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#ifndef __NR_exit
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# error Cannot do syscall exit
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#endif
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#ifdef SSP_SMASH_DUMPS_CORE
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# define ENABLE_SSP_SMASH_DUMPS_CORE 1
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# if !defined _KERNEL_NSIG && !defined _NSIG
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# error No _NSIG or _KERNEL_NSIG for rt_sigaction
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# endif
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# if !defined __NR_sigaction && !defined __NR_rt_sigaction
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# error Cannot do syscall sigaction or rt_sigaction
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# endif
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/* Although rt_sigaction expects sizeof(sigset_t) - it expects the size
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* of the _kernel_ sigset_t which is not the same as the user sigset_t.
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* Most arches have this as _NSIG bits - mips has _KERNEL_NSIG bits for
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* some reason.
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*/
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# ifdef _KERNEL_NSIG
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# define _SSP_NSIG _KERNEL_NSIG
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# else
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# define _SSP_NSIG _NSIG
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# endif
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#else
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# define _SSP_NSIG 0
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# define ENABLE_SSP_SMASH_DUMPS_CORE 0
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#endif
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/* Define DO_SIGACTION - default to newer rt signal interface but
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* fallback to old as needed.
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*/
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#ifdef __NR_rt_sigaction
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# define DO_SIGACTION(signum, act, oldact) \
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INLINE_SYSCALL(rt_sigaction, 4, signum, act, oldact, _SSP_NSIG/8)
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#else
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# define DO_SIGACTION(signum, act, oldact) \
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INLINE_SYSCALL(sigaction, 3, signum, act, oldact)
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#endif
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/* Define DO_SOCKET/DO_CONNECT functions to deal with socketcall vs socket/connect */
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#if defined(__NR_socket) && defined(__NR_connect)
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# define USE_OLD_SOCKETCALL 0
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#else
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# define USE_OLD_SOCKETCALL 1
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#endif
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/* stub out the __NR_'s so we can let gcc optimize away dead code */
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#ifndef __NR_socketcall
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# define __NR_socketcall 0
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#endif
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#ifndef __NR_socket
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# define __NR_socket 0
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#endif
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#ifndef __NR_connect
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# define __NR_connect 0
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#endif
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#define DO_SOCKET(result, domain, type, protocol) \
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do { \
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if (USE_OLD_SOCKETCALL) { \
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socketargs[0] = domain; \
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socketargs[1] = type; \
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socketargs[2] = protocol; \
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socketargs[3] = 0; \
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result = INLINE_SYSCALL(socketcall, 2, SOCKOP_socket, socketargs); \
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} else \
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result = INLINE_SYSCALL(socket, 3, domain, type, protocol); \
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} while (0)
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#define DO_CONNECT(result, sockfd, serv_addr, addrlen) \
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do { \
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if (USE_OLD_SOCKETCALL) { \
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socketargs[0] = sockfd; \
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socketargs[1] = (unsigned long int)serv_addr; \
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socketargs[2] = addrlen; \
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socketargs[3] = 0; \
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result = INLINE_SYSCALL(socketcall, 2, SOCKOP_connect, socketargs); \
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} else \
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result = INLINE_SYSCALL(connect, 3, sockfd, serv_addr, addrlen); \
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} while (0)
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#ifndef _PATH_LOG
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# define _PATH_LOG "/dev/log"
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#endif
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static const char path_log[] = _PATH_LOG;
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/* For building glibc with SSP switched on, define __progname to a
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* constant if building for the run-time loader, to avoid pulling
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* in more of libc.so into ld.so
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*/
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#ifdef IS_IN_rtld
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static char *__progname = "<rtld>";
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#else
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extern char *__progname;
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#endif
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/* Common handler code, used by stack_chk_fail and __stack_smash_handler
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* Inlined to ensure no self-references to the handler within itself.
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* Data static to avoid putting more than necessary on the stack,
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* to aid core debugging.
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*/
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__attribute__ ((__noreturn__ , __always_inline__))
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static inline void
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__hardened_gentoo_stack_chk_fail(char func[], int damaged)
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{
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#define MESSAGE_BUFSIZ 256
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static pid_t pid;
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static int plen, i;
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static char message[MESSAGE_BUFSIZ];
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static const char msg_ssa[] = ": stack smashing attack";
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static const char msg_inf[] = " in function ";
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static const char msg_ssd[] = "*** stack smashing detected ***: ";
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static const char msg_terminated[] = " - terminated\n";
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static const char msg_report[] = "Report to http://bugs.gentoo.org/\n";
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static const char msg_unknown[] = "<unknown>";
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static int log_socket, connect_result;
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static struct sockaddr_un sock;
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static unsigned long int socketargs[4];
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/* Build socket address
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*/
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sock.sun_family = AF_UNIX;
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i = 0;
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while ((path_log[i] != '\0') && (i<(sizeof(sock.sun_path)-1))) {
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sock.sun_path[i] = path_log[i];
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i++;
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}
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sock.sun_path[i] = '\0';
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/* Try SOCK_DGRAM connection to syslog */
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connect_result = -1;
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DO_SOCKET(log_socket, AF_UNIX, SOCK_DGRAM, 0);
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if (log_socket != -1)
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DO_CONNECT(connect_result, log_socket, &sock, sizeof(sock));
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if (connect_result == -1) {
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if (log_socket != -1)
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INLINE_SYSCALL(close, 1, log_socket);
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/* Try SOCK_STREAM connection to syslog */
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DO_SOCKET(log_socket, AF_UNIX, SOCK_STREAM, 0);
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if (log_socket != -1)
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DO_CONNECT(connect_result, log_socket, &sock, sizeof(sock));
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}
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/* Build message. Messages are generated both in the old style and new style,
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* so that log watchers that are configured for the old-style message continue
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* to work.
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*/
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#define strconcat(str) \
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{i=0; while ((str[i] != '\0') && ((i+plen)<(MESSAGE_BUFSIZ-1))) \
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{\
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message[plen+i]=str[i];\
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i++;\
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}\
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plen+=i;}
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/* R.Henderson post-gcc-4 style message */
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plen = 0;
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strconcat(msg_ssd);
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if (__progname != (char *)0)
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strconcat(__progname)
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else
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strconcat(msg_unknown);
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strconcat(msg_terminated);
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/* Write out error message to STDERR, to syslog if open */
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INLINE_SYSCALL(write, 3, STDERR_FILENO, message, plen);
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if (connect_result != -1)
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INLINE_SYSCALL(write, 3, log_socket, message, plen);
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/* Dr. Etoh pre-gcc-4 style message */
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plen = 0;
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if (__progname != (char *)0)
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strconcat(__progname)
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else
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strconcat(msg_unknown);
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strconcat(msg_ssa);
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strconcat(msg_inf);
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if (func != NULL)
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strconcat(func)
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else
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strconcat(msg_unknown);
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strconcat(msg_terminated);
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/* Write out error message to STDERR, to syslog if open */
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INLINE_SYSCALL(write, 3, STDERR_FILENO, message, plen);
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if (connect_result != -1)
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INLINE_SYSCALL(write, 3, log_socket, message, plen);
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/* Direct reports to bugs.gentoo.org */
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plen=0;
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strconcat(msg_report);
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message[plen++]='\0';
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/* Write out error message to STDERR, to syslog if open */
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INLINE_SYSCALL(write, 3, STDERR_FILENO, message, plen);
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if (connect_result != -1)
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INLINE_SYSCALL(write, 3, log_socket, message, plen);
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if (log_socket != -1)
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INLINE_SYSCALL(close, 1, log_socket);
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/* Suicide */
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pid = INLINE_SYSCALL(getpid, 0);
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if (ENABLE_SSP_SMASH_DUMPS_CORE) {
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static struct sigaction default_abort_act;
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/* Remove any user-supplied handler for SIGABRT, before using it */
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default_abort_act.sa_handler = SIG_DFL;
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default_abort_act.sa_sigaction = NULL;
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__sigfillset(&default_abort_act.sa_mask);
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default_abort_act.sa_flags = 0;
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if (DO_SIGACTION(SIGABRT, &default_abort_act, NULL) == 0)
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INLINE_SYSCALL(kill, 2, pid, SIGABRT);
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}
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/* Note; actions cannot be added to SIGKILL */
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INLINE_SYSCALL(kill, 2, pid, SIGKILL);
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/* In case the kill didn't work, exit anyway
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* The loop prevents gcc thinking this routine returns
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*/
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while (1)
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INLINE_SYSCALL(exit, 0);
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}
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__attribute__ ((__noreturn__))
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void __stack_chk_fail(void)
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{
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__hardened_gentoo_stack_chk_fail(NULL, 0);
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}
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#ifdef ENABLE_OLD_SSP_COMPAT
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__attribute__ ((__noreturn__))
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void __stack_smash_handler(char func[], int damaged)
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{
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__hardened_gentoo_stack_chk_fail(func, damaged);
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}
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#endif
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