freebsd-skq/lib/libc/stdlib/system.c
Konstantin Belousov bd6060a1c6 Switch libc from using _sig{procmask,action,suspend} symbols, which
are aliases for the syscall stubs and are plt-interposed, to the
libc-private aliases of internally interposed sigprocmask() etc.

Since e.g. _sigaction is not interposed by libthr, calling signal()
removes thr_sighandler() from the handler slot etc.  The result was
breaking signal semantic and rtld locking.

The added __libc_sigprocmask and other symbols are hidden, they are
not exported and cannot be called through PLT.  The setjmp/longjmp
functions for x86 were changed to use direct calls, and since
PIC_PROLOGUE only needed for functional PLT indirection on i386, it is
removed as well.

The PowerPC bug of calling the syscall directly in the setjmp/longjmp
implementation is kept as is.

Reported by:	Pete French <petefrench@ingresso.co.uk>
Tested by:	Michiel Boland <boland37@xs4all.nl>
Reviewed by:	jilles (previous version)
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2015-08-29 14:25:01 +00:00

113 lines
3.8 KiB
C

/*
* Copyright (c) 1988, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)system.c 8.1 (Berkeley) 6/4/93";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "namespace.h"
#include <sys/types.h>
#include <sys/wait.h>
#include <signal.h>
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <unistd.h>
#include <paths.h>
#include <errno.h>
#include "un-namespace.h"
#include "libc_private.h"
#pragma weak system
int
system(const char *command)
{
return (((int (*)(const char *))
__libc_interposing[INTERPOS_system])(command));
}
int
__libc_system(const char *command)
{
pid_t pid, savedpid;
int pstat;
struct sigaction ign, intact, quitact;
sigset_t newsigblock, oldsigblock;
if (!command) /* just checking... */
return(1);
(void)sigemptyset(&newsigblock);
(void)sigaddset(&newsigblock, SIGCHLD);
(void)sigaddset(&newsigblock, SIGINT);
(void)sigaddset(&newsigblock, SIGQUIT);
(void)__libc_sigprocmask(SIG_BLOCK, &newsigblock, &oldsigblock);
switch(pid = vfork()) {
/*
* In the child, use unwrapped syscalls. libthr is in
* undefined state after vfork().
*/
case -1: /* error */
(void)__libc_sigprocmask(SIG_SETMASK, &oldsigblock, NULL);
return (-1);
case 0: /* child */
/*
* Restore original signal dispositions and exec the command.
*/
(void)__sys_sigprocmask(SIG_SETMASK, &oldsigblock, NULL);
execl(_PATH_BSHELL, "sh", "-c", command, (char *)NULL);
_exit(127);
}
/*
* If we are running means that the child has either completed
* its execve, or has failed.
* Block SIGINT/QUIT because sh -c handles it and wait for
* it to clean up.
*/
memset(&ign, 0, sizeof(ign));
ign.sa_handler = SIG_IGN;
(void)sigemptyset(&ign.sa_mask);
(void)__libc_sigaction(SIGINT, &ign, &intact);
(void)__libc_sigaction(SIGQUIT, &ign, &quitact);
savedpid = pid;
do {
pid = _wait4(savedpid, &pstat, 0, (struct rusage *)0);
} while (pid == -1 && errno == EINTR);
(void)__libc_sigaction(SIGINT, &intact, NULL);
(void)__libc_sigaction(SIGQUIT, &quitact, NULL);
(void)__libc_sigprocmask(SIG_SETMASK, &oldsigblock, NULL);
return (pid == -1 ? -1 : pstat);
}
__weak_reference(__libc_system, __system);
__weak_reference(__libc_system, _system);