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/*
* Copyright (c) 2016 Todd C. Miller <Todd.Miller@sudo.ws>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <config.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <stdio.h>
#include <stdlib.h>
#ifdef HAVE_STDBOOL_H
# include <stdbool.h>
#else
# include "compat/stdbool.h"
#endif /* HAVE_STDBOOL_H */
#ifdef HAVE_STRING_H
# include <string.h>
#endif /* HAVE_STRING_H */
#ifdef HAVE_STRINGS_H
# include <strings.h>
#endif /* HAVE_STRINGS_H */
#ifdef HAVE_WORDEXP_H
# include <wordexp.h>
#endif
#include <signal.h>
#include <unistd.h>
#include <limits.h>
#include <errno.h>
#include "sudo_compat.h"
#include "sudo_fatal.h"
#include "sudo_util.h"
#include "sudo_exec.h"
__dso_public int main(int argc, char *argv[], char *envp[]);
static bool
report_status(int status, const char *what)
{
bool ret = false;
/* system() returns -1 for exec failure. */
if (status == -1) {
printf("%s: OK (%s)\n", getprogname(), what);
return true;
}
/* check exit value, expecting 127 for failure */
if (WIFEXITED(status)) {
int exitval = WEXITSTATUS(status);
if (exitval == 127) {
printf("%s: OK (%s)\n", getprogname(), what);
ret = true;
} else {
printf("%s: FAIL (%s) [%d]\n", getprogname(), what, exitval);
}
} else if (WIFSIGNALED(status)) {
printf("%s: FAIL (%s) [signal %d]\n", getprogname(), what,
WTERMSIG(status));
} else {
/* should not happen */
printf("%s: FAIL (%s) [status %d]\n", getprogname(), what, status);
}
return ret;
}
static int
try_execl(void)
{
pid_t child, pid;
int status;
child = fork();
switch (child) {
case -1:
sudo_fatal_nodebug("fork");
case 0:
/* child */
/* Try to exec /bin/true, else exit with value 127. */
execl("/bin/true", "true", (char *)0);
_exit(127);
default:
/* parent */
do {
pid = waitpid(child, &status, 0);
} while (pid == -1 && errno == EINTR);
if (pid == -1)
sudo_fatal_nodebug("waitpid");
if (report_status(status, "execl"))
return 0;
return 1;
}
}
static int
try_system(void)
{
int status;
/* Try to run /bin/true, system() returns 127 on exec failure. */
status = system("/bin/true > /dev/null 2>&1");
if (report_status(status, "system"))
return 0;
return 1;
}
#ifdef HAVE_WORDEXP_H
static int
try_wordexp(void)
{
wordexp_t we;
int rc, ret = 1;
/*
* sudo_noexec.so prevents command substitution via the WRDE_NOCMD flag
* where possible.
*/
rc = wordexp("$(/bin/echo foo)", &we, 0);
switch (rc) {
case -1:
/* sudo's wordexp() wrapper returns -1 if RTLD_NEXT is not supported. */
case 127:
/* Solaris 10 wordexp() returns 127 for execve() failure. */
#ifdef WRDE_ERRNO
case WRDE_ERRNO:
/* Solaris 11 wordexp() returns WRDE_ERRNO for execve() failure. */
#endif
printf("%s: OK (wordexp) [%d]\n", getprogname(), rc);
ret = 0;
break;
case WRDE_SYNTAX:
/* FreeBSD returns WRDE_SYNTAX if it can't write to the shell process */
printf("%s: OK (wordexp) [WRDE_SYNTAX]\n", getprogname());
ret = 0;
break;
case WRDE_CMDSUB:
printf("%s: OK (wordexp) [WRDE_CMDSUB]\n", getprogname());
ret = 0;
break;
case 0:
/*
* On HP-UX 11.00 we don't seem to be able to add WRDE_NOCMD
* but the execve() wrapper prevents the command substitution.
*/
if (we.we_wordc == 0) {
printf("%s: OK (wordexp) [%d]\n", getprogname(), rc);
wordfree(&we);
ret = 0;
break;
}
wordfree(&we);
/* FALLTHROUGH */
default:
printf("%s: FAIL (wordexp) [%d]\n", getprogname(), rc);
break;
}
return ret;
}
#endif
int
main(int argc, char *argv[], char *envp[])
{
int errors = 0;
initprogname(argc > 0 ? argv[0] : "check_noexec");
if (argc != 2) {
fprintf(stderr, "usage: %s regress | /path/to/sudo_noexec.so\n", getprogname());
exit(1);
}
/* Disable execution for post-exec and re-exec ourself. */
if (strcmp(argv[1], "rexec") != 0) {
const char *noexec = argv[1];
argv[1] = "rexec";
execve(argv[0], argv, disable_execute(envp, noexec));
sudo_fatalx_nodebug("execve");
}
errors += try_execl();
errors += try_system();
#ifdef HAVE_WORDEXP_H
errors += try_wordexp();
#endif
return errors;
}
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