1 /*
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2019-2023, Juniper Networks, Inc.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
22 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <sys/types.h>
30 #include <sys/param.h>
31 #include <sys/errno.h>
32 #include <sys/mac.h>
33
34 #include <unistd.h>
35 #include <fcntl.h>
36 #include <string.h>
37 #include <syslog.h>
38
39 #include <security/mac_grantbylabel/mac_grantbylabel.h>
40
41 #include "libveriexec.h"
42
43 static char *
find_interpreter(const char * script)44 find_interpreter(const char *script)
45 {
46 static const char ws[] = " \t\n\r";
47 static char buf[MAXPATHLEN+4]; /* allow space for #! etc */
48 char *cp;
49 int fd;
50 int n;
51
52 cp = NULL;
53 if ((fd = open(script, O_RDONLY)) >= 0) {
54 if ((n = read(fd, buf, sizeof(buf))) > 0) {
55 if (strncmp(buf, "#!", 2) == 0) {
56 buf[sizeof(buf) - 1] = '\0';
57 cp = &buf[2];
58 if ((n = strspn(cp, ws)) > 0)
59 cp += n;
60 if ((n = strcspn(cp, ws)) > 0) {
61 cp[n] = '\0';
62 } else {
63 cp = NULL;
64 }
65 }
66 }
67 close(fd);
68 }
69 return (cp);
70 }
71
72 /**
73 * @brief exec a python or similar script
74 *
75 * Python and similar scripts must normally be signed and
76 * run directly rather than fed to the interpreter which
77 * is not normally allowed to be run directly.
78 *
79 * If direct execv of script fails due to EAUTH
80 * and process has GBL_VERIEXEC syslog event and run via
81 * interpreter.
82 *
83 * If interpreter is NULL look at first block of script
84 * to find ``#!`` magic.
85 *
86 * @prarm[in] interpreter
87 * if NULL, extract from script if necessary
88 *
89 * @prarm[in] argv
90 * argv for execv(2)
91 * argv[0] must be full path.
92 * Python at least requires argv[1] to also be the script path.
93 *
94 * @return
95 * error on failure usually EPERM or EAUTH
96 */
97 int
execv_script(const char * interpreter,char * const * argv)98 execv_script(const char *interpreter, char * const *argv)
99 {
100 const char *script;
101 int rc;
102
103 script = argv[0];
104 if (veriexec_check_path(script) == 0) {
105 rc = execv(script, argv);
106 }
107 /* still here? we might be allowed to run via interpreter */
108 if (gbl_check_pid(0) & GBL_VERIEXEC) {
109 if (!interpreter)
110 interpreter = find_interpreter(script);
111 if (interpreter) {
112 syslog(LOG_NOTICE, "running %s via %s",
113 script, interpreter);
114 rc = execv(interpreter, argv);
115 }
116 }
117 return (rc);
118 }
119
120 #if defined(MAIN) || defined(UNIT_TEST)
121 #include <sys/wait.h>
122 #include <err.h>
123
124 int
main(int argc __unused,char * argv[])125 main(int argc __unused, char *argv[])
126 {
127 const char *interp;
128 int c;
129 int s;
130 pid_t child;
131
132 openlog("exec_script", LOG_PID|LOG_PERROR, LOG_DAEMON);
133
134 interp = NULL;
135 while ((c = getopt(argc, argv, "i:")) != -1) {
136 switch (c) {
137 case 'i':
138 interp = optarg;
139 break;
140 default:
141 errx(1, "unknown option: -%c", c);
142 break;
143 }
144 }
145 argc -= optind;
146 argv += optind;
147 /* we need a child */
148 child = fork();
149 if (child < 0)
150 err(2, "fork");
151 if (child == 0) {
152 c = execv_script(interp, argv);
153 err(2, "exec_script(%s,%s)", interp, argv[0]);
154 }
155 c = waitpid(child, &s, 0);
156 printf("%s: exit %d\n", argv[0], WEXITSTATUS(s));
157 return (0);
158 }
159 #endif
160