xbps/lib/external/fexec.c
Juan RP d36d37fc6a lib/external/fexec.c: fix potential insecure usage in vfork().
Reported by clang-analyzer.

After reading the linux man-pages vfork(2) manpage I came to the
conclusion that it's better to change the behaviour of the
original source (NetBSD) and change this to use fork(2).
2019-06-18 18:49:29 +02:00

140 lines
3.4 KiB
C

/*-
* Copyright (c) 2003 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Matthias Scheler.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
#define _BSD_SOURCE /* for vfork and chroot */
#define _DEFAULT_SOURCE /* glibc>=2.20 */
#include <sys/types.h>
#include <unistd.h>
#include <sys/wait.h>
#include <errno.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#undef _DEFAULT_SOURCE
#undef _BSD_SOURCE
#include "xbps_api_impl.h"
static int
pfcexec(struct xbps_handle *xhp, const char *file, const char **argv)
{
pid_t child;
int status;
child = fork();
switch (child) {
case 0:
/*
* If rootdir != / and uid==0 and bin/sh exists,
* change root directory and exec command.
*/
if (strcmp(xhp->rootdir, "/")) {
if ((geteuid() == 0) && (access("bin/sh", X_OK) == 0)) {
if (chroot(xhp->rootdir) == -1) {
xbps_dbg_printf(xhp, "%s: chroot() "
"failed: %s\n", *argv, strerror(errno));
_exit(errno);
}
if (chdir("/") == -1) {
xbps_dbg_printf(xhp, "%s: chdir() "
"failed: %s\n", *argv, strerror(errno));
_exit(errno);
}
}
}
umask(022);
(void)execv(file, __UNCONST(argv));
_exit(errno);
/* NOTREACHED */
case -1:
return -1;
}
while (waitpid(child, &status, 0) < 0) {
if (errno != EINTR)
return -1;
}
if (!WIFEXITED(status))
return -1;
return WEXITSTATUS(status);
}
static int
vfcexec(struct xbps_handle *xhp, const char *arg, va_list ap)
{
const char **argv;
size_t argv_size, argc;
int retval;
argv_size = 16;
if ((argv = malloc(argv_size * sizeof(*argv))) == NULL) {
errno = ENOMEM;
return -1;
}
argv[0] = arg;
argc = 1;
do {
if (argc == argv_size) {
argv_size *= 2;
argv = realloc(argv, argv_size * sizeof(*argv));
if (argv == NULL) {
errno = ENOMEM;
return -1;
}
}
arg = va_arg(ap, const char *);
argv[argc++] = arg;
} while (arg != NULL);
retval = pfcexec(xhp, argv[0], argv);
free(argv);
return retval;
}
int HIDDEN
xbps_file_exec(struct xbps_handle *xhp, const char *arg, ...)
{
va_list ap;
int result;
va_start(ap, arg);
result = vfcexec(xhp, arg, ap);
va_end(ap);
return result;
}