VERSION: Bump version up to 3.6.20.
[Samba.git] / source3 / smbd / sec_ctx.c
blob14e18a8a22e8866bd70741c4793e885ba00266a5
1 /*
2 Unix SMB/CIFS implementation.
3 uid/user handling
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/>.
20 #include "includes.h"
21 #include "smbd/smbd.h"
22 #include "smbd/globals.h"
23 #include "libcli/security/security_token.h"
24 #include "auth.h"
25 #include "smbprofile.h"
27 extern struct current_user current_user;
29 /****************************************************************************
30 Are two UNIX tokens equal ?
31 ****************************************************************************/
33 bool unix_token_equal(const struct security_unix_token *t1, const struct security_unix_token *t2)
35 if (t1->uid != t2->uid || t1->gid != t2->gid ||
36 t1->ngroups != t2->ngroups) {
37 return false;
39 if (memcmp(t1->groups, t2->groups,
40 t1->ngroups*sizeof(gid_t)) != 0) {
41 return false;
43 return true;
46 /****************************************************************************
47 Become the specified uid.
48 ****************************************************************************/
50 static bool become_uid(uid_t uid)
52 /* Check for dodgy uid values */
54 if (uid == (uid_t)-1 ||
55 ((sizeof(uid_t) == 2) && (uid == (uid_t)65535))) {
56 if (!become_uid_done) {
57 DEBUG(1,("WARNING: using uid %d is a security risk\n",
58 (int)uid));
59 become_uid_done = true;
63 /* Set effective user id */
65 set_effective_uid(uid);
67 DO_PROFILE_INC(uid_changes);
68 return True;
71 /****************************************************************************
72 Become the specified gid.
73 ****************************************************************************/
75 static bool become_gid(gid_t gid)
77 /* Check for dodgy gid values */
79 if (gid == (gid_t)-1 || ((sizeof(gid_t) == 2) &&
80 (gid == (gid_t)65535))) {
81 if (!become_gid_done) {
82 DEBUG(1,("WARNING: using gid %d is a security risk\n",
83 (int)gid));
84 become_gid_done = true;
88 /* Set effective group id */
90 set_effective_gid(gid);
91 return True;
94 /****************************************************************************
95 Become the specified uid and gid.
96 ****************************************************************************/
98 static bool become_id(uid_t uid, gid_t gid)
100 return become_gid(gid) && become_uid(uid);
103 /****************************************************************************
104 Drop back to root privileges in order to change to another user.
105 ****************************************************************************/
107 static void gain_root(void)
109 if (non_root_mode()) {
110 return;
113 if (geteuid() != 0) {
114 set_effective_uid(0);
116 if (geteuid() != 0) {
117 DEBUG(0,
118 ("Warning: You appear to have a trapdoor "
119 "uid system\n"));
123 if (getegid() != 0) {
124 set_effective_gid(0);
126 if (getegid() != 0) {
127 DEBUG(0,
128 ("Warning: You appear to have a trapdoor "
129 "gid system\n"));
134 /****************************************************************************
135 Get the list of current groups.
136 ****************************************************************************/
138 static int get_current_groups(gid_t gid, uint32_t *p_ngroups, gid_t **p_groups)
140 int i;
141 gid_t grp;
142 int ngroups;
143 gid_t *groups = NULL;
145 (*p_ngroups) = 0;
146 (*p_groups) = NULL;
148 /* this looks a little strange, but is needed to cope with
149 systems that put the current egid in the group list
150 returned from getgroups() (tridge) */
151 save_re_gid();
152 set_effective_gid(gid);
153 setgid(gid);
155 ngroups = sys_getgroups(0,&grp);
156 if (ngroups <= 0) {
157 goto fail;
160 if((groups = SMB_MALLOC_ARRAY(gid_t, ngroups+1)) == NULL) {
161 DEBUG(0,("setup_groups malloc fail !\n"));
162 goto fail;
165 if ((ngroups = sys_getgroups(ngroups,groups)) == -1) {
166 goto fail;
169 restore_re_gid();
171 (*p_ngroups) = ngroups;
172 (*p_groups) = groups;
174 DEBUG( 4, ( "get_current_groups: user is in %u groups: ", ngroups));
175 for (i = 0; i < ngroups; i++ ) {
176 DEBUG( 4, ( "%s%d", (i ? ", " : ""), (int)groups[i] ) );
178 DEBUG( 4, ( "\n" ) );
180 return ngroups;
182 fail:
183 SAFE_FREE(groups);
184 restore_re_gid();
185 return -1;
188 /****************************************************************************
189 Create a new security context on the stack. It is the same as the old
190 one. User changes are done using the set_sec_ctx() function.
191 ****************************************************************************/
193 bool push_sec_ctx(void)
195 struct sec_ctx *ctx_p;
197 /* Check we don't overflow our stack */
199 if (sec_ctx_stack_ndx == MAX_SEC_CTX_DEPTH) {
200 DEBUG(0, ("Security context stack overflow!\n"));
201 smb_panic("Security context stack overflow!");
204 /* Store previous user context */
206 sec_ctx_stack_ndx++;
208 ctx_p = &sec_ctx_stack[sec_ctx_stack_ndx];
210 ctx_p->ut.uid = geteuid();
211 ctx_p->ut.gid = getegid();
213 DEBUG(4, ("push_sec_ctx(%u, %u) : sec_ctx_stack_ndx = %d\n",
214 (unsigned int)ctx_p->ut.uid, (unsigned int)ctx_p->ut.gid, sec_ctx_stack_ndx ));
216 ctx_p->token = dup_nt_token(NULL,
217 sec_ctx_stack[sec_ctx_stack_ndx-1].token);
219 ctx_p->ut.ngroups = sys_getgroups(0, NULL);
221 if (ctx_p->ut.ngroups != 0) {
222 if (!(ctx_p->ut.groups = SMB_MALLOC_ARRAY(gid_t, ctx_p->ut.ngroups))) {
223 DEBUG(0, ("Out of memory in push_sec_ctx()\n"));
224 TALLOC_FREE(ctx_p->token);
225 return False;
228 sys_getgroups(ctx_p->ut.ngroups, ctx_p->ut.groups);
229 } else {
230 ctx_p->ut.groups = NULL;
233 return True;
236 /****************************************************************************
237 Change UNIX security context. Calls panic if not successful so no return value.
238 ****************************************************************************/
240 #ifndef HAVE_DARWIN_INITGROUPS
242 /* Normal credential switch path. */
244 static void set_unix_security_ctx(uid_t uid, gid_t gid, int ngroups, gid_t *groups)
246 /* Start context switch */
247 gain_root();
248 #ifdef HAVE_SETGROUPS
249 if (sys_setgroups(gid, ngroups, groups) != 0 && !non_root_mode()) {
250 smb_panic("sys_setgroups failed");
252 #endif
253 become_id(uid, gid);
254 /* end context switch */
257 #else /* HAVE_DARWIN_INITGROUPS */
259 /* The Darwin groups implementation is a little unusual. The list of
260 * groups in the kernel credential is not exhaustive, but more like
261 * a cache. The full group list is held in userspace and checked
262 * dynamically.
264 * This is an optional mechanism, and setgroups(2) opts out
265 * of it. That is, if you call setgroups, then the list of groups you
266 * set are the only groups that are ever checked. This is not what we
267 * want. We want to opt in to the dynamic resolution mechanism, so we
268 * need to specify the uid of the user whose group list (cache) we are
269 * setting.
271 * The Darwin rules are:
272 * 1. Thou shalt setegid, initgroups and seteuid IN THAT ORDER
273 * 2. Thou shalt not pass more that NGROUPS_MAX to initgroups
274 * 3. Thou shalt leave the first entry in the groups list well alone
277 #include <sys/syscall.h>
279 static void set_unix_security_ctx(uid_t uid, gid_t gid, int ngroups, gid_t *groups)
281 int max = groups_max();
283 /* Start context switch */
284 gain_root();
286 become_gid(gid);
289 if (syscall(SYS_initgroups, (ngroups > max) ? max : ngroups,
290 groups, uid) == -1 && !non_root_mode()) {
291 DEBUG(0, ("WARNING: failed to set group list "
292 "(%d groups) for UID %ld: %s\n",
293 ngroups, uid, strerror(errno)));
294 smb_panic("sys_setgroups failed");
297 become_uid(uid);
298 /* end context switch */
301 #endif /* HAVE_DARWIN_INITGROUPS */
303 /****************************************************************************
304 Set the current security context to a given user.
305 ****************************************************************************/
307 void set_sec_ctx(uid_t uid, gid_t gid, int ngroups, gid_t *groups, const struct security_token *token)
309 struct sec_ctx *ctx_p = &sec_ctx_stack[sec_ctx_stack_ndx];
311 /* Set the security context */
313 DEBUG(4, ("setting sec ctx (%u, %u) - sec_ctx_stack_ndx = %d\n",
314 (unsigned int)uid, (unsigned int)gid, sec_ctx_stack_ndx));
316 security_token_debug(DBGC_CLASS, 5, token);
317 debug_unix_user_token(DBGC_CLASS, 5, uid, gid, ngroups, groups);
319 /* Change uid, gid and supplementary group list. */
320 set_unix_security_ctx(uid, gid, ngroups, groups);
322 ctx_p->ut.ngroups = ngroups;
324 SAFE_FREE(ctx_p->ut.groups);
325 if (token && (token == ctx_p->token)) {
326 smb_panic("DUPLICATE_TOKEN");
329 TALLOC_FREE(ctx_p->token);
331 if (ngroups) {
332 ctx_p->ut.groups = (gid_t *)memdup(groups,
333 sizeof(gid_t) * ngroups);
334 if (!ctx_p->ut.groups) {
335 smb_panic("memdup failed");
337 } else {
338 ctx_p->ut.groups = NULL;
341 if (token) {
342 ctx_p->token = dup_nt_token(NULL, token);
343 if (!ctx_p->token) {
344 smb_panic("dup_nt_token failed");
346 } else {
347 ctx_p->token = NULL;
350 ctx_p->ut.uid = uid;
351 ctx_p->ut.gid = gid;
353 /* Update current_user stuff */
355 current_user.ut.uid = uid;
356 current_user.ut.gid = gid;
357 current_user.ut.ngroups = ngroups;
358 current_user.ut.groups = groups;
359 current_user.nt_user_token = ctx_p->token;
362 /****************************************************************************
363 Become root context.
364 ****************************************************************************/
366 void set_root_sec_ctx(void)
368 /* May need to worry about supplementary groups at some stage */
370 set_sec_ctx(0, 0, 0, NULL, NULL);
373 /****************************************************************************
374 Pop a security context from the stack.
375 ****************************************************************************/
377 bool pop_sec_ctx(void)
379 struct sec_ctx *ctx_p;
380 struct sec_ctx *prev_ctx_p;
382 /* Check for stack underflow */
384 if (sec_ctx_stack_ndx == 0) {
385 DEBUG(0, ("Security context stack underflow!\n"));
386 smb_panic("Security context stack underflow!");
389 ctx_p = &sec_ctx_stack[sec_ctx_stack_ndx];
391 /* Clear previous user info */
393 ctx_p->ut.uid = (uid_t)-1;
394 ctx_p->ut.gid = (gid_t)-1;
396 SAFE_FREE(ctx_p->ut.groups);
397 ctx_p->ut.ngroups = 0;
399 TALLOC_FREE(ctx_p->token);
401 /* Pop back previous user */
403 sec_ctx_stack_ndx--;
405 prev_ctx_p = &sec_ctx_stack[sec_ctx_stack_ndx];
407 /* Change uid, gid and supplementary group list. */
408 set_unix_security_ctx(prev_ctx_p->ut.uid,
409 prev_ctx_p->ut.gid,
410 prev_ctx_p->ut.ngroups,
411 prev_ctx_p->ut.groups);
413 /* Update current_user stuff */
415 current_user.ut.uid = prev_ctx_p->ut.uid;
416 current_user.ut.gid = prev_ctx_p->ut.gid;
417 current_user.ut.ngroups = prev_ctx_p->ut.ngroups;
418 current_user.ut.groups = prev_ctx_p->ut.groups;
419 current_user.nt_user_token = prev_ctx_p->token;
421 DEBUG(4, ("pop_sec_ctx (%u, %u) - sec_ctx_stack_ndx = %d\n",
422 (unsigned int)geteuid(), (unsigned int)getegid(), sec_ctx_stack_ndx));
424 return True;
427 /* Initialise the security context system */
429 void init_sec_ctx(void)
431 int i;
432 struct sec_ctx *ctx_p;
434 /* Initialise security context stack */
436 memset(sec_ctx_stack, 0, sizeof(struct sec_ctx) * MAX_SEC_CTX_DEPTH);
438 for (i = 0; i < MAX_SEC_CTX_DEPTH; i++) {
439 sec_ctx_stack[i].ut.uid = (uid_t)-1;
440 sec_ctx_stack[i].ut.gid = (gid_t)-1;
443 /* Initialise first level of stack. It is the current context */
444 ctx_p = &sec_ctx_stack[0];
446 ctx_p->ut.uid = geteuid();
447 ctx_p->ut.gid = getegid();
449 get_current_groups(ctx_p->ut.gid, &ctx_p->ut.ngroups, &ctx_p->ut.groups);
451 ctx_p->token = NULL; /* Maps to guest user. */
453 /* Initialise current_user global */
455 current_user.ut.uid = ctx_p->ut.uid;
456 current_user.ut.gid = ctx_p->ut.gid;
457 current_user.ut.ngroups = ctx_p->ut.ngroups;
458 current_user.ut.groups = ctx_p->ut.groups;
460 /* The conn and vuid are usually taken care of by other modules.
461 We initialise them here. */
463 current_user.conn = NULL;
464 current_user.vuid = UID_FIELD_INVALID;
465 current_user.nt_user_token = NULL;