2 * Copyright (c) 2008 Dan Walsh <dwalsh@redhat.com>
4 * Borrowed heavily from newrole source code
8 * Steve Grubb <sgrubb@redhat.com>
9 * Darrel Goeddel <DGoeddel@trustedcs.com>
10 * Michael Thompson <mcthomps@us.ibm.com>
11 * Dan Walsh <dwalsh@redhat.com>
13 * Permission to use, copy, modify, and distribute this software for any
14 * purpose with or without fee is hereby granted, provided that the above
15 * copyright notice and this permission notice appear in all copies.
17 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
18 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
19 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
20 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
21 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
22 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
23 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
28 #include <sys/types.h>
43 #include <selinux/flask.h> /* for SECCLASS_CHR_FILE */
44 #include <selinux/selinux.h> /* for is_selinux_enabled() */
45 #include <selinux/context.h> /* for context-mangling functions */
46 #include <selinux/get_default_type.h>
47 #include <selinux/get_context_list.h>
50 #include "pathnames.h"
53 __unused static const char rcsid[] = "$Sudo: selinux.c,v 1.2.2.4 2008/02/22 20:33:10 millert Exp $";
57 * This function attempts to revert the relabeling done to the tty.
58 * fd - referencing the opened ttyn
59 * ttyn - name of tty to restore
60 * tty_context - original context of the tty
61 * new_tty_context - context tty was relabeled to
63 * Returns zero on success, non-zero otherwise
66 restore_tty_label(int fd, const char *ttyn, security_context_t tty_context,
67 security_context_t new_tty_context)
70 security_context_t chk_tty_context = NULL;
78 /* Verify that the tty still has the context set by sudo. */
79 if ((rc = fgetfilecon(fd, &chk_tty_context)) < 0) {
80 warn("unable to fgetfilecon %s", ttyn);
84 if ((rc = strcmp(chk_tty_context, new_tty_context))) {
85 warnx("%s changed labels.", ttyn);
89 if ((rc = fsetfilecon(fd, tty_context)) < 0)
90 warn("unable to restore context for %s", ttyn);
93 freecon(chk_tty_context);
98 * This function attempts to relabel the tty. If this function fails, then
99 * the fd is closed, the contexts are free'd and -1 is returned. On success,
100 * a valid fd is returned and tty_context and new_tty_context are set.
102 * This function will not fail if it can not relabel the tty when selinux is
103 * in permissive mode.
106 relabel_tty(const char *ttyn, security_context_t new_context,
107 security_context_t * tty_context, security_context_t * new_tty_context,
111 security_context_t tty_con = NULL;
112 security_context_t new_tty_con = NULL;
117 /* Re-open TTY descriptor */
118 fd = open(ttyn, O_RDWR | O_NONBLOCK);
120 warn("unable to open %s", ttyn);
123 (void)fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, 0) & ~O_NONBLOCK);
125 if (fgetfilecon(fd, &tty_con) < 0) {
126 warn("unable to get current context for %s, not relabeling tty",
132 if (tty_con && (security_compute_relabel(new_context, tty_con,
133 SECCLASS_CHR_FILE, &new_tty_con) < 0)) {
134 warn("unable to get new context for %s, not relabeling tty", ttyn);
139 if (new_tty_con != NULL) {
140 if (fsetfilecon(fd, new_tty_con) < 0) {
141 warn("unable to set new context for %s", ttyn);
147 *tty_context = tty_con;
148 *new_tty_context = new_tty_con;
158 * Returns a new security context based on the old context and the
159 * specified role and type.
162 get_exec_context(security_context_t old_context, char *role, char *type)
164 security_context_t new_context = NULL;
165 context_t context = NULL;
166 char *typebuf = NULL;
168 /* We must have a role, the type is optional (we can use the default). */
170 warnx("you must specify a role.");
174 if (get_default_type(role, &typebuf)) {
175 warnx("unable to get default type");
182 * Expand old_context into a context_t so that we extract and modify
183 * its components easily.
185 context = context_new(old_context);
188 * Replace the role and type in "context" with the role and
189 * type we will be running the command as.
191 if (context_role_set(context, role)) {
192 warnx("failed to set new role %s", role);
195 if (context_type_set(context, type)) {
196 warnx("failed to set new type %s", type);
201 * Convert "context" back into a string and verify it.
203 new_context = estrdup(context_str(context));
204 if (security_check_context(new_context) < 0) {
205 warnx("%s is not a valid context", new_context);
210 warnx("Your new context is %s", new_context);
213 context_free(context);
218 context_free(context);
219 freecon(new_context);
224 * If the program is being run with a different security context we
225 * need to go through an intermediary process for the transition to
226 * be allowed by the policy. We use the "sesh" shell for this, which
227 * will simply execute the command pass to it on the command line.
230 selinux_exec(char *role, char *type, char **argv, char **envp, int login_shell)
232 security_context_t old_context = NULL;
233 security_context_t new_context = NULL;
234 security_context_t tty_context = NULL;
235 security_context_t new_tty_context = NULL;
237 int enforcing, ttyfd;
239 /* Must have a tty. */
240 if (user_ttypath == NULL || *user_ttypath == '\0')
241 err(EXIT_FAILURE, "unable to determine tty");
243 /* Store the caller's SID in old_context. */
244 if (getprevcon(&old_context))
245 err(EXIT_FAILURE, "failed to get old_context");
247 enforcing = security_getenforce();
249 err(EXIT_FAILURE, "unable to determine enforcing mode.");
253 warnx("your old context was %s", old_context);
255 new_context = get_exec_context(old_context, role, type);
259 ttyfd = relabel_tty(user_ttypath, new_context, &tty_context,
260 &new_tty_context, enforcing);
262 err(EXIT_FAILURE, "unable to setup tty context for %s", new_context);
265 warnx("your old tty context is %s", tty_context);
266 warnx("your new tty context is %s", new_tty_context);
271 /* fork failed, no child to worry about */
272 warn("unable to fork");
273 if (restore_tty_label(ttyfd, user_ttypath, tty_context, new_tty_context))
274 warnx("unable to restore tty label");
276 } else if (childPid) {
280 /* Parent, wait for child to finish. */
282 pid = waitpid(childPid, &status, 0);
283 } while (pid == -1 && errno == EINTR);
286 err(EXIT_FAILURE, "waitpid");
288 if (restore_tty_label(ttyfd, user_ttypath, tty_context, new_tty_context))
289 errx(EXIT_FAILURE, "unable to restore tty label");
291 /* Preserve child exit status. */
292 if (WIFEXITED(status))
293 exit(WEXITSTATUS(status));
297 /* Close the tty and reopen descriptors 0 through 2 */
298 if (close(ttyfd) || close(STDIN_FILENO) || close(STDOUT_FILENO) ||
299 close(STDERR_FILENO)) {
300 warn("could not close descriptors");
303 ttyfd = open(user_ttypath, O_RDONLY | O_NONBLOCK);
304 if (ttyfd != STDIN_FILENO)
306 fcntl(ttyfd, F_SETFL, fcntl(ttyfd, F_GETFL, 0) & ~O_NONBLOCK);
307 ttyfd = open(user_ttypath, O_RDWR | O_NONBLOCK);
308 if (ttyfd != STDOUT_FILENO)
310 fcntl(ttyfd, F_SETFL, fcntl(ttyfd, F_GETFL, 0) & ~O_NONBLOCK);
311 ttyfd = dup(STDOUT_FILENO);
312 if (ttyfd != STDERR_FILENO)
315 if (setexeccon(new_context)) {
316 warn("unable to set exec context to %s", new_context);
321 if (setkeycreatecon(new_context)) {
322 warn("unable to set key creation context to %s", new_context);
328 if (send_audit_message(1, old_context, new_context, user_ttypath))
332 /* We use the "spare" slot in argv to store sesh. */
334 argv[0] = login_shell ? "-sesh" : "sesh";
337 execve(_PATH_SUDO_SESH, argv, envp);
338 warn("%s", safe_cmnd);