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>
42 #include <selinux/flask.h> /* for SECCLASS_CHR_FILE */
43 #include <selinux/selinux.h> /* for is_selinux_enabled() */
44 #include <selinux/context.h> /* for context-mangling functions */
45 #include <selinux/get_default_type.h>
46 #include <selinux/get_context_list.h>
49 #include "pathnames.h"
52 * This function attempts to revert the relabeling done to the tty.
53 * fd - referencing the opened ttyn
54 * ttyn - name of tty to restore
55 * tty_context - original context of the tty
56 * new_tty_context - context tty was relabeled to
58 * Returns zero on success, non-zero otherwise
61 restore_tty_label(int fd, const char *ttyn, security_context_t tty_context,
62 security_context_t new_tty_context)
65 security_context_t chk_tty_context = NULL;
73 /* Verify that the tty still has the context set by sudo. */
74 if ((rc = fgetfilecon(fd, &chk_tty_context)) < 0) {
75 warning("unable to fgetfilecon %s", ttyn);
79 if ((rc = strcmp(chk_tty_context, new_tty_context))) {
80 warningx("%s changed labels.", ttyn);
84 if ((rc = fsetfilecon(fd, tty_context)) < 0)
85 warning("unable to restore context for %s", ttyn);
88 freecon(chk_tty_context);
93 * This function attempts to relabel the tty. If this function fails, then
94 * the fd is closed, the contexts are free'd and -1 is returned. On success,
95 * a valid fd is returned and tty_context and new_tty_context are set.
97 * This function will not fail if it can not relabel the tty when selinux is
101 relabel_tty(const char *ttyn, security_context_t new_context,
102 security_context_t * tty_context, security_context_t * new_tty_context,
106 security_context_t tty_con = NULL;
107 security_context_t new_tty_con = NULL;
112 /* Re-open TTY descriptor */
113 fd = open(ttyn, O_RDWR | O_NONBLOCK);
115 warning("unable to open %s", ttyn);
118 (void)fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, 0) & ~O_NONBLOCK);
120 if (fgetfilecon(fd, &tty_con) < 0) {
121 warning("unable to get current context for %s, not relabeling tty",
127 if (tty_con && (security_compute_relabel(new_context, tty_con,
128 SECCLASS_CHR_FILE, &new_tty_con) < 0)) {
129 warning("unable to get new context for %s, not relabeling tty", ttyn);
134 if (new_tty_con != NULL) {
135 if (fsetfilecon(fd, new_tty_con) < 0) {
136 warning("unable to set new context for %s", ttyn);
142 *tty_context = tty_con;
143 *new_tty_context = new_tty_con;
153 * Returns a new security context based on the old context and the
154 * specified role and type.
157 get_exec_context(security_context_t old_context, char *role, char *type)
159 security_context_t new_context = NULL;
160 context_t context = NULL;
161 char *typebuf = NULL;
163 /* We must have a role, the type is optional (we can use the default). */
165 warningx("you must specify a role.");
169 if (get_default_type(role, &typebuf)) {
170 warningx("unable to get default type");
177 * Expand old_context into a context_t so that we extract and modify
178 * its components easily.
180 context = context_new(old_context);
183 * Replace the role and type in "context" with the role and
184 * type we will be running the command as.
186 if (context_role_set(context, role)) {
187 warningx("failed to set new role %s", role);
190 if (context_type_set(context, type)) {
191 warningx("failed to set new type %s", type);
196 * Convert "context" back into a string and verify it.
198 new_context = estrdup(context_str(context));
199 if (security_check_context(new_context) < 0) {
200 warningx("%s is not a valid context", new_context);
205 warningx("Your new context is %s", new_context);
208 context_free(context);
213 context_free(context);
214 freecon(new_context);
219 * If the program is being run with a different security context we
220 * need to go through an intermediary process for the transition to
221 * be allowed by the policy. We use the "sesh" shell for this, which
222 * will simply execute the command pass to it on the command line.
225 selinux_exec(char *role, char *type, char **argv, int login_shell)
227 security_context_t old_context = NULL;
228 security_context_t new_context = NULL;
229 security_context_t tty_context = NULL;
230 security_context_t new_tty_context = NULL;
232 int enforcing, ttyfd;
234 /* Must have a tty. */
235 if (user_ttypath == NULL || *user_ttypath == '\0')
236 error(EXIT_FAILURE, "unable to determine tty");
238 /* Store the caller's SID in old_context. */
239 if (getprevcon(&old_context))
240 error(EXIT_FAILURE, "failed to get old_context");
242 enforcing = security_getenforce();
244 error(EXIT_FAILURE, "unable to determine enforcing mode.");
248 warningx("your old context was %s", old_context);
250 new_context = get_exec_context(old_context, role, type);
254 ttyfd = relabel_tty(user_ttypath, new_context, &tty_context,
255 &new_tty_context, enforcing);
257 error(EXIT_FAILURE, "unable to setup tty context for %s", new_context);
260 warningx("your old tty context is %s", tty_context);
261 warningx("your new tty context is %s", new_tty_context);
266 /* fork failed, no child to worry about */
267 warning("unable to fork");
268 if (restore_tty_label(ttyfd, user_ttypath, tty_context, new_tty_context))
269 warningx("unable to restore tty label");
271 } else if (childPid) {
275 /* Parent, wait for child to finish. */
277 pid = waitpid(childPid, &status, 0);
278 } while (pid == -1 && errno == EINTR);
281 error(EXIT_FAILURE, "waitpid");
283 if (restore_tty_label(ttyfd, user_ttypath, tty_context, new_tty_context))
284 errorx(EXIT_FAILURE, "unable to restore tty label");
286 /* Preserve child exit status. */
287 if (WIFEXITED(status))
288 exit(WEXITSTATUS(status));
292 /* Close the tty and reopen descriptors 0 through 2 */
293 if (close(ttyfd) || close(STDIN_FILENO) || close(STDOUT_FILENO) ||
294 close(STDERR_FILENO)) {
295 warning("could not close descriptors");
298 ttyfd = open(user_ttypath, O_RDONLY | O_NONBLOCK);
299 if (ttyfd != STDIN_FILENO)
301 fcntl(ttyfd, F_SETFL, fcntl(ttyfd, F_GETFL, 0) & ~O_NONBLOCK);
302 ttyfd = open(user_ttypath, O_RDWR | O_NONBLOCK);
303 if (ttyfd != STDOUT_FILENO)
305 fcntl(ttyfd, F_SETFL, fcntl(ttyfd, F_GETFL, 0) & ~O_NONBLOCK);
306 ttyfd = dup(STDOUT_FILENO);
307 if (ttyfd != STDERR_FILENO)
310 if (setexeccon(new_context)) {
311 warning("unable to set exec context to %s", new_context);
316 if (setkeycreatecon(new_context)) {
317 warning("unable to set key creation context to %s", new_context);
323 if (send_audit_message(1, old_context, new_context, user_ttypath))
327 /* We use the "spare" slot in argv to store sesh. */
329 argv[0] = login_shell ? "-sesh" : "sesh";
332 execv(_PATH_SUDO_SESH, argv);
333 warning("%s", safe_cmnd);