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/*
* SPDX-License-Identifier: BSD-2-Clause
*
* Copyright (c) 2019-2023, Juniper Networks, Inc.
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
*/
#include <sys/types.h>
#include <sys/param.h>
#include <sys/errno.h>
#include <sys/mac.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <syslog.h>
#include <security/mac_grantbylabel/mac_grantbylabel.h>
#include "libveriexec.h"
static char *
find_interpreter(const char *script)
{
static const char ws[] = " \t\n\r";
static char buf[MAXPATHLEN+4]; /* allow space for #! etc */
char *cp;
int fd;
int n;
cp = NULL;
if ((fd = open(script, O_RDONLY)) >= 0) {
if ((n = read(fd, buf, sizeof(buf))) > 0) {
if (strncmp(buf, "#!", 2) == 0) {
buf[sizeof(buf) - 1] = '\0';
cp = &buf[2];
if ((n = strspn(cp, ws)) > 0)
cp += n;
if ((n = strcspn(cp, ws)) > 0) {
cp[n] = '\0';
} else {
cp = NULL;
}
}
}
close(fd);
}
return (cp);
}
/**
* @brief exec a python or similar script
*
* Python and similar scripts must normally be signed and
* run directly rather than fed to the interpreter which
* is not normally allowed to be run directly.
*
* If direct execv of script fails due to EAUTH
* and process has GBL_VERIEXEC syslog event and run via
* interpreter.
*
* If interpreter is NULL look at first block of script
* to find ``#!`` magic.
*
* @prarm[in] interpreter
* if NULL, extract from script if necessary
*
* @prarm[in] argv
* argv for execv(2)
* argv[0] must be full path.
* Python at least requires argv[1] to also be the script path.
*
* @return
* error on failure usually EPERM or EAUTH
*/
int
execv_script(const char *interpreter, char * const *argv)
{
const char *script;
int rc;
script = argv[0];
if (veriexec_check_path(script) == 0) {
rc = execv(script, argv);
}
/* still here? we might be allowed to run via interpreter */
if (gbl_check_pid(0) & GBL_VERIEXEC) {
if (!interpreter)
interpreter = find_interpreter(script);
if (interpreter) {
syslog(LOG_NOTICE, "running %s via %s",
script, interpreter);
rc = execv(interpreter, argv);
}
}
return (rc);
}
#if defined(MAIN) || defined(UNIT_TEST)
#include <sys/wait.h>
#include <err.h>
int
main(int argc __unused, char *argv[])
{
const char *interp;
int c;
int s;
pid_t child;
openlog("exec_script", LOG_PID|LOG_PERROR, LOG_DAEMON);
interp = NULL;
while ((c = getopt(argc, argv, "i:")) != -1) {
switch (c) {
case 'i':
interp = optarg;
break;
default:
errx(1, "unknown option: -%c", c);
break;
}
}
argc -= optind;
argv += optind;
/* we need a child */
child = fork();
if (child < 0)
err(2, "fork");
if (child == 0) {
c = execv_script(interp, argv);
err(2, "exec_script(%s,%s)", interp, argv[0]);
}
c = waitpid(child, &s, 0);
printf("%s: exit %d\n", argv[0], WEXITSTATUS(s));
return (0);
}
#endif
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