2 * Copyright (c) 2009-2010 Todd C. Miller <Todd.Miller@courtesan.com>
3 * Copyright (c) 2008 Dan Walsh <dwalsh@redhat.com>
5 * Borrowed heavily from newrole source code
9 * Steve Grubb <sgrubb@redhat.com>
10 * Darrel Goeddel <DGoeddel@trustedcs.com>
11 * Michael Thompson <mcthomps@us.ibm.com>
12 * Dan Walsh <dwalsh@redhat.com>
14 * Permission to use, copy, modify, and distribute this software for any
15 * purpose with or without fee is hereby granted, provided that the above
16 * copyright notice and this permission notice appear in all copies.
18 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
19 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
20 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
21 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
22 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
23 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
24 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
29 #include <sys/types.h>
39 #ifdef HAVE_LINUX_AUDIT
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 "linux_audit.h"
52 static struct selinux_state {
53 security_context_t old_context;
54 security_context_t new_context;
55 security_context_t tty_context;
56 security_context_t new_tty_context;
63 * This function attempts to revert the relabeling done to the tty.
64 * fd - referencing the opened ttyn
65 * ttyn - name of tty to restore
67 * Returns zero on success, non-zero otherwise
70 selinux_restore_tty(void)
73 security_context_t chk_tty_context = NULL;
75 if (se_state.ttyfd == -1 || se_state.new_tty_context == NULL)
78 /* Verify that the tty still has the context set by sudo. */
79 if ((retval = fgetfilecon(se_state.ttyfd, &chk_tty_context)) < 0) {
80 warning("unable to fgetfilecon %s", se_state.ttyn);
84 if ((retval = strcmp(chk_tty_context, se_state.new_tty_context))) {
85 warningx("%s changed labels.", se_state.ttyn);
89 if ((retval = fsetfilecon(se_state.ttyfd, se_state.tty_context)) < 0)
90 warning("unable to restore context for %s", se_state.ttyn);
93 if (se_state.ttyfd != -1) {
94 close(se_state.ttyfd);
97 if (chk_tty_context != NULL) {
98 freecon(chk_tty_context);
99 chk_tty_context = NULL;
105 * This function attempts to relabel the tty. If this function fails, then
106 * the contexts are free'd and -1 is returned. On success, 0 is returned
107 * and tty_context and new_tty_context are set.
109 * This function will not fail if it can not relabel the tty when selinux is
110 * in permissive mode.
113 relabel_tty(const char *ttyn, int ptyfd)
115 security_context_t tty_con = NULL;
116 security_context_t new_tty_con = NULL;
119 se_state.ttyfd = ptyfd;
121 /* It is perfectly legal to have no tty. */
122 if (ptyfd == -1 && ttyn == NULL)
125 /* If sudo is not allocating a pty for the command, open current tty. */
127 se_state.ttyfd = open(ttyn, O_RDWR|O_NONBLOCK);
128 if (se_state.ttyfd == -1) {
129 warning("unable to open %s, not relabeling tty", ttyn);
130 if (se_state.enforcing)
133 (void)fcntl(se_state.ttyfd, F_SETFL,
134 fcntl(se_state.ttyfd, F_GETFL, 0) & ~O_NONBLOCK);
137 if (fgetfilecon(se_state.ttyfd, &tty_con) < 0) {
138 warning("unable to get current tty context, not relabeling tty");
139 if (se_state.enforcing)
143 if (tty_con && (security_compute_relabel(se_state.new_context, tty_con,
144 SECCLASS_CHR_FILE, &new_tty_con) < 0)) {
145 warning("unable to get new tty context, not relabeling tty");
146 if (se_state.enforcing)
150 if (new_tty_con != NULL) {
151 if (fsetfilecon(se_state.ttyfd, new_tty_con) < 0) {
152 warning("unable to set new tty context");
153 if (se_state.enforcing)
159 /* Reopen pty that was relabeled, std{in,out,err} are reset later. */
160 se_state.ttyfd = open(ttyn, O_RDWR|O_NOCTTY, 0);
161 if (se_state.ttyfd == -1) {
162 warning("cannot open %s", ttyn);
163 if (se_state.enforcing)
166 if (dup2(se_state.ttyfd, ptyfd) == -1) {
171 /* Re-open tty to get new label and reset std{in,out,err} */
172 close(se_state.ttyfd);
173 se_state.ttyfd = open(ttyn, O_RDWR|O_NONBLOCK);
174 if (se_state.ttyfd == -1) {
175 warning("unable to open %s", ttyn);
178 (void)fcntl(se_state.ttyfd, F_SETFL,
179 fcntl(se_state.ttyfd, F_GETFL, 0) & ~O_NONBLOCK);
180 for (fd = STDIN_FILENO; fd <= STDERR_FILENO; fd++) {
181 if (isatty(fd) && dup2(se_state.ttyfd, fd) == -1) {
187 /* Retain se_state.ttyfd so we can restore label when command finishes. */
188 (void)fcntl(se_state.ttyfd, F_SETFD, FD_CLOEXEC);
190 se_state.ttyn = ttyn;
191 se_state.tty_context = tty_con;
192 se_state.new_tty_context = new_tty_con;
196 if (se_state.ttyfd != -1 && se_state.ttyfd != ptyfd) {
197 close(se_state.ttyfd);
205 * Returns a new security context based on the old context and the
206 * specified role and type.
209 get_exec_context(security_context_t old_context, const char *role, const char *type)
211 security_context_t new_context = NULL;
212 context_t context = NULL;
213 char *typebuf = NULL;
215 /* We must have a role, the type is optional (we can use the default). */
217 warningx("you must specify a role for type %s", type);
222 if (get_default_type(role, &typebuf)) {
223 warningx("unable to get default type for role %s", role);
231 * Expand old_context into a context_t so that we extract and modify
232 * its components easily.
234 context = context_new(old_context);
237 * Replace the role and type in "context" with the role and
238 * type we will be running the command as.
240 if (context_role_set(context, role)) {
241 warning("failed to set new role %s", role);
244 if (context_type_set(context, type)) {
245 warning("failed to set new type %s", type);
250 * Convert "context" back into a string and verify it.
252 new_context = estrdup(context_str(context));
253 if (security_check_context(new_context) < 0) {
254 warningx("%s is not a valid context", new_context);
260 warningx("Your new context is %s", new_context);
263 context_free(context);
268 context_free(context);
269 freecon(new_context);
274 * Set the exec and tty contexts in preparation for fork/exec.
275 * Must run as root, before the uid change.
276 * If ptyfd is not -1, it indicates we are running
277 * in a pty and do not need to reset std{in,out,err}.
278 * Returns 0 on success and -1 on failure.
281 selinux_setup(const char *role, const char *type, const char *ttyn,
286 /* Store the caller's SID in old_context. */
287 if (getprevcon(&se_state.old_context)) {
288 warning("failed to get old_context");
292 se_state.enforcing = security_getenforce();
293 if (se_state.enforcing < 0) {
294 warning("unable to determine enforcing mode.");
299 warningx("your old context was %s", se_state.old_context);
301 se_state.new_context = get_exec_context(se_state.old_context, role, type);
302 if (!se_state.new_context)
305 if (relabel_tty(ttyn, ptyfd) < 0) {
306 warning("unable to setup tty context for %s", se_state.new_context);
311 if (se_state.ttyfd != -1) {
312 warningx("your old tty context is %s", se_state.tty_context);
313 warningx("your new tty context is %s", se_state.new_tty_context);
317 #ifdef HAVE_LINUX_AUDIT
318 linux_audit_role_change(se_state.old_context, se_state.new_context,
329 selinux_execve(const char *path, char *argv[], char *envp[])
331 if (setexeccon(se_state.new_context)) {
332 warning("unable to set exec context to %s", se_state.new_context);
333 if (se_state.enforcing)
337 #ifdef HAVE_SETKEYCREATECON
338 if (setkeycreatecon(se_state.new_context)) {
339 warning("unable to set key creation context to %s", se_state.new_context);
340 if (se_state.enforcing)
343 #endif /* HAVE_SETKEYCREATECON */
345 /* We use the "spare" slot in argv to store sesh. */
347 argv[0] = *argv[1] == '-' ? "-sesh" : "sesh";
348 argv[1] = (char *)path;
350 execve(_PATH_SUDO_SESH, argv, envp);