2 Unix SMB/CIFS implementation.
4 Copyright (C) Tim Potter 2000
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>.
21 #include "smbd/smbd.h"
22 #include "smbd/globals.h"
23 #include "libcli/security/security_token.h"
26 extern struct current_user current_user;
28 /****************************************************************************
29 Are two UNIX tokens equal ?
30 ****************************************************************************/
32 bool unix_token_equal(const struct security_unix_token *t1, const struct security_unix_token *t2)
34 if (t1->uid != t2->uid || t1->gid != t2->gid ||
35 t1->ngroups != t2->ngroups) {
38 if (memcmp(t1->groups, t2->groups,
39 t1->ngroups*sizeof(gid_t)) != 0) {
45 /****************************************************************************
46 Become the specified uid.
47 ****************************************************************************/
49 static bool become_uid(uid_t uid)
51 /* Check for dodgy uid values */
53 if (uid == (uid_t)-1 ||
54 ((sizeof(uid_t) == 2) && (uid == (uid_t)65535))) {
55 if (!become_uid_done) {
56 DEBUG(1,("WARNING: using uid %d is a security risk\n",
58 become_uid_done = true;
62 /* Set effective user id */
64 set_effective_uid(uid);
66 DO_PROFILE_INC(uid_changes);
70 /****************************************************************************
71 Become the specified gid.
72 ****************************************************************************/
74 static bool become_gid(gid_t gid)
76 /* Check for dodgy gid values */
78 if (gid == (gid_t)-1 || ((sizeof(gid_t) == 2) &&
79 (gid == (gid_t)65535))) {
80 if (!become_gid_done) {
81 DEBUG(1,("WARNING: using gid %d is a security risk\n",
83 become_gid_done = true;
87 /* Set effective group id */
89 set_effective_gid(gid);
93 /****************************************************************************
94 Become the specified uid and gid.
95 ****************************************************************************/
97 static bool become_id(uid_t uid, gid_t gid)
99 return become_gid(gid) && become_uid(uid);
102 /****************************************************************************
103 Drop back to root privileges in order to change to another user.
104 ****************************************************************************/
106 static void gain_root(void)
108 if (non_root_mode()) {
112 if (geteuid() != 0) {
113 set_effective_uid(0);
115 if (geteuid() != 0) {
117 ("Warning: You appear to have a trapdoor "
122 if (getegid() != 0) {
123 set_effective_gid(0);
125 if (getegid() != 0) {
127 ("Warning: You appear to have a trapdoor "
133 /****************************************************************************
134 Get the list of current groups.
135 ****************************************************************************/
137 static int get_current_groups(gid_t gid, uint32_t *p_ngroups, gid_t **p_groups)
142 gid_t *groups = NULL;
147 /* this looks a little strange, but is needed to cope with
148 systems that put the current egid in the group list
149 returned from getgroups() (tridge) */
151 set_effective_gid(gid);
154 ngroups = sys_getgroups(0,&grp);
159 if((groups = SMB_MALLOC_ARRAY(gid_t, ngroups+1)) == NULL) {
160 DEBUG(0,("setup_groups malloc fail !\n"));
164 if ((ngroups = sys_getgroups(ngroups,groups)) == -1) {
170 (*p_ngroups) = ngroups;
171 (*p_groups) = groups;
173 DEBUG( 4, ( "get_current_groups: user is in %u groups: ", ngroups));
174 for (i = 0; i < ngroups; i++ ) {
175 DEBUG( 4, ( "%s%d", (i ? ", " : ""), (int)groups[i] ) );
177 DEBUG( 4, ( "\n" ) );
187 /****************************************************************************
188 Create a new security context on the stack. It is the same as the old
189 one. User changes are done using the set_sec_ctx() function.
190 ****************************************************************************/
192 bool push_sec_ctx(void)
194 struct sec_ctx *ctx_p;
196 /* Check we don't overflow our stack */
198 if (sec_ctx_stack_ndx == MAX_SEC_CTX_DEPTH) {
199 DEBUG(0, ("Security context stack overflow!\n"));
200 smb_panic("Security context stack overflow!");
203 /* Store previous user context */
207 ctx_p = &sec_ctx_stack[sec_ctx_stack_ndx];
209 ctx_p->ut.uid = geteuid();
210 ctx_p->ut.gid = getegid();
212 DEBUG(4, ("push_sec_ctx(%u, %u) : sec_ctx_stack_ndx = %d\n",
213 (unsigned int)ctx_p->ut.uid, (unsigned int)ctx_p->ut.gid, sec_ctx_stack_ndx ));
215 ctx_p->token = dup_nt_token(NULL,
216 sec_ctx_stack[sec_ctx_stack_ndx-1].token);
218 ctx_p->ut.ngroups = sys_getgroups(0, NULL);
220 if (ctx_p->ut.ngroups != 0) {
221 if (!(ctx_p->ut.groups = SMB_MALLOC_ARRAY(gid_t, ctx_p->ut.ngroups))) {
222 DEBUG(0, ("Out of memory in push_sec_ctx()\n"));
223 TALLOC_FREE(ctx_p->token);
227 sys_getgroups(ctx_p->ut.ngroups, ctx_p->ut.groups);
229 ctx_p->ut.groups = NULL;
235 /****************************************************************************
236 Change UNIX security context. Calls panic if not successful so no return value.
237 ****************************************************************************/
239 #ifndef HAVE_DARWIN_INITGROUPS
241 /* Normal credential switch path. */
243 static void set_unix_security_ctx(uid_t uid, gid_t gid, int ngroups, gid_t *groups)
245 /* Start context switch */
247 #ifdef HAVE_SETGROUPS
248 if (sys_setgroups(gid, ngroups, groups) != 0 && !non_root_mode()) {
249 smb_panic("sys_setgroups failed");
253 /* end context switch */
256 #else /* HAVE_DARWIN_INITGROUPS */
258 /* The Darwin groups implementation is a little unusual. The list of
259 * groups in the kernel credential is not exhaustive, but more like
260 * a cache. The full group list is held in userspace and checked
263 * This is an optional mechanism, and setgroups(2) opts out
264 * of it. That is, if you call setgroups, then the list of groups you
265 * set are the only groups that are ever checked. This is not what we
266 * want. We want to opt in to the dynamic resolution mechanism, so we
267 * need to specify the uid of the user whose group list (cache) we are
270 * The Darwin rules are:
271 * 1. Thou shalt setegid, initgroups and seteuid IN THAT ORDER
272 * 2. Thou shalt not pass more that NGROUPS_MAX to initgroups
273 * 3. Thou shalt leave the first entry in the groups list well alone
276 #include <sys/syscall.h>
278 static void set_unix_security_ctx(uid_t uid, gid_t gid, int ngroups, gid_t *groups)
280 int max = groups_max();
282 /* Start context switch */
288 if (syscall(SYS_initgroups, (ngroups > max) ? max : ngroups,
289 groups, uid) == -1 && !non_root_mode()) {
290 DEBUG(0, ("WARNING: failed to set group list "
291 "(%d groups) for UID %ld: %s\n",
292 ngroups, uid, strerror(errno)));
293 smb_panic("sys_setgroups failed");
297 /* end context switch */
300 #endif /* HAVE_DARWIN_INITGROUPS */
302 /****************************************************************************
303 Set the current security context to a given user.
304 ****************************************************************************/
306 void set_sec_ctx(uid_t uid, gid_t gid, int ngroups, gid_t *groups, struct security_token *token)
308 struct sec_ctx *ctx_p = &sec_ctx_stack[sec_ctx_stack_ndx];
310 /* Set the security context */
312 DEBUG(4, ("setting sec ctx (%u, %u) - sec_ctx_stack_ndx = %d\n",
313 (unsigned int)uid, (unsigned int)gid, sec_ctx_stack_ndx));
315 security_token_debug(DBGC_CLASS, 5, token);
316 debug_unix_user_token(DBGC_CLASS, 5, uid, gid, ngroups, groups);
318 /* Change uid, gid and supplementary group list. */
319 set_unix_security_ctx(uid, gid, ngroups, groups);
321 ctx_p->ut.ngroups = ngroups;
323 SAFE_FREE(ctx_p->ut.groups);
324 if (token && (token == ctx_p->token)) {
325 smb_panic("DUPLICATE_TOKEN");
328 TALLOC_FREE(ctx_p->token);
331 ctx_p->ut.groups = (gid_t *)memdup(groups,
332 sizeof(gid_t) * ngroups);
333 if (!ctx_p->ut.groups) {
334 smb_panic("memdup failed");
337 ctx_p->ut.groups = NULL;
341 ctx_p->token = dup_nt_token(NULL, token);
343 smb_panic("dup_nt_token failed");
352 /* Update current_user stuff */
354 current_user.ut.uid = uid;
355 current_user.ut.gid = gid;
356 current_user.ut.ngroups = ngroups;
357 current_user.ut.groups = groups;
358 current_user.nt_user_token = ctx_p->token;
361 /****************************************************************************
363 ****************************************************************************/
365 void set_root_sec_ctx(void)
367 /* May need to worry about supplementary groups at some stage */
369 set_sec_ctx(0, 0, 0, NULL, NULL);
372 /****************************************************************************
373 Pop a security context from the stack.
374 ****************************************************************************/
376 bool pop_sec_ctx(void)
378 struct sec_ctx *ctx_p;
379 struct sec_ctx *prev_ctx_p;
381 /* Check for stack underflow */
383 if (sec_ctx_stack_ndx == 0) {
384 DEBUG(0, ("Security context stack underflow!\n"));
385 smb_panic("Security context stack underflow!");
388 ctx_p = &sec_ctx_stack[sec_ctx_stack_ndx];
390 /* Clear previous user info */
392 ctx_p->ut.uid = (uid_t)-1;
393 ctx_p->ut.gid = (gid_t)-1;
395 SAFE_FREE(ctx_p->ut.groups);
396 ctx_p->ut.ngroups = 0;
398 TALLOC_FREE(ctx_p->token);
400 /* Pop back previous user */
404 prev_ctx_p = &sec_ctx_stack[sec_ctx_stack_ndx];
406 /* Change uid, gid and supplementary group list. */
407 set_unix_security_ctx(prev_ctx_p->ut.uid,
409 prev_ctx_p->ut.ngroups,
410 prev_ctx_p->ut.groups);
412 /* Update current_user stuff */
414 current_user.ut.uid = prev_ctx_p->ut.uid;
415 current_user.ut.gid = prev_ctx_p->ut.gid;
416 current_user.ut.ngroups = prev_ctx_p->ut.ngroups;
417 current_user.ut.groups = prev_ctx_p->ut.groups;
418 current_user.nt_user_token = prev_ctx_p->token;
420 DEBUG(4, ("pop_sec_ctx (%u, %u) - sec_ctx_stack_ndx = %d\n",
421 (unsigned int)geteuid(), (unsigned int)getegid(), sec_ctx_stack_ndx));
426 /* Initialise the security context system */
428 void init_sec_ctx(void)
431 struct sec_ctx *ctx_p;
433 /* Initialise security context stack */
435 memset(sec_ctx_stack, 0, sizeof(struct sec_ctx) * MAX_SEC_CTX_DEPTH);
437 for (i = 0; i < MAX_SEC_CTX_DEPTH; i++) {
438 sec_ctx_stack[i].ut.uid = (uid_t)-1;
439 sec_ctx_stack[i].ut.gid = (gid_t)-1;
442 /* Initialise first level of stack. It is the current context */
443 ctx_p = &sec_ctx_stack[0];
445 ctx_p->ut.uid = geteuid();
446 ctx_p->ut.gid = getegid();
448 get_current_groups(ctx_p->ut.gid, &ctx_p->ut.ngroups, &ctx_p->ut.groups);
450 ctx_p->token = NULL; /* Maps to guest user. */
452 /* Initialise current_user global */
454 current_user.ut.uid = ctx_p->ut.uid;
455 current_user.ut.gid = ctx_p->ut.gid;
456 current_user.ut.ngroups = ctx_p->ut.ngroups;
457 current_user.ut.groups = ctx_p->ut.groups;
459 /* The conn and vuid are usually taken care of by other modules.
460 We initialise them here. */
462 current_user.conn = NULL;
463 current_user.vuid = UID_FIELD_INVALID;
464 current_user.nt_user_token = NULL;