1 /*-
2 * Copyright (c) 1999-2002, 2007-2008 Robert N. M. Watson
3 * Copyright (c) 2001-2005 Networks Associates Technology, Inc.
4 * Copyright (c) 2005 Tom Rhodes
5 * Copyright (c) 2006 SPARTA, Inc.
6 * All rights reserved.
7 *
8 * This software was developed by Robert Watson for the TrustedBSD Project.
9 * It was later enhanced by Tom Rhodes for the TrustedBSD Project.
10 *
11 * This software was developed for the FreeBSD Project in part by Network
12 * Associates Laboratories, the Security Research Division of Network
13 * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"),
14 * as part of the DARPA CHATS research program.
15 *
16 * This software was enhanced by SPARTA ISSO under SPAWAR contract
17 * N66001-04-C-6019 ("SEFOS").
18 *
19 * Redistribution and use in source and binary forms, with or without
20 * modification, are permitted provided that the following conditions
21 * are met:
22 * 1. Redistributions of source code must retain the above copyright
23 * notice, this list of conditions and the following disclaimer.
24 * 2. Redistributions in binary form must reproduce the above copyright
25 * notice, this list of conditions and the following disclaimer in the
26 * documentation and/or other materials provided with the distribution.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
38 * SUCH DAMAGE.
39 */
40
41 /*
42 * Developed by the TrustedBSD Project.
43 *
44 * "BSD Extended" MAC policy, allowing the administrator to impose mandatory
45 * firewall-like rules regarding users and file system objects.
46 */
47
48 #include <sys/param.h>
49 #include <sys/acl.h>
50 #include <sys/kernel.h>
51 #include <sys/jail.h>
52 #include <sys/lock.h>
53 #include <sys/malloc.h>
54 #include <sys/module.h>
55 #include <sys/mount.h>
56 #include <sys/mutex.h>
57 #include <sys/priv.h>
58 #include <sys/proc.h>
59 #include <sys/systm.h>
60 #include <sys/vnode.h>
61 #include <sys/sysctl.h>
62 #include <sys/syslog.h>
63 #include <sys/stat.h>
64
65 #include <security/mac/mac_policy.h>
66 #include <security/mac_bsdextended/mac_bsdextended.h>
67 #include <security/mac_bsdextended/ugidfw_internal.h>
68
69 static struct mtx ugidfw_mtx;
70
71 SYSCTL_DECL(_security_mac);
72
73 static SYSCTL_NODE(_security_mac, OID_AUTO, bsdextended,
74 CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
75 "TrustedBSD extended BSD MAC policy controls");
76
77 static int ugidfw_enabled = 1;
78 SYSCTL_INT(_security_mac_bsdextended, OID_AUTO, enabled, CTLFLAG_RWTUN,
79 &ugidfw_enabled, 0, "Enforce extended BSD policy");
80
81 static MALLOC_DEFINE(M_MACBSDEXTENDED, "mac_bsdextended",
82 "BSD Extended MAC rule");
83
84 #define MAC_BSDEXTENDED_MAXRULES 250
85 static struct mac_bsdextended_rule *rules[MAC_BSDEXTENDED_MAXRULES];
86 static int rule_count = 0;
87 static int rule_slots = 0;
88 static int rule_version = MB_VERSION;
89
90 SYSCTL_INT(_security_mac_bsdextended, OID_AUTO, rule_count, CTLFLAG_RD,
91 &rule_count, 0, "Number of defined rules\n");
92 SYSCTL_INT(_security_mac_bsdextended, OID_AUTO, rule_slots, CTLFLAG_RD,
93 &rule_slots, 0, "Number of used rule slots\n");
94 SYSCTL_INT(_security_mac_bsdextended, OID_AUTO, rule_version, CTLFLAG_RD,
95 &rule_version, 0, "Version number for API\n");
96
97 /*
98 * This is just used for logging purposes, eventually we would like to log
99 * much more then failed requests.
100 */
101 static int ugidfw_logging;
102 SYSCTL_INT(_security_mac_bsdextended, OID_AUTO, logging, CTLFLAG_RW,
103 &ugidfw_logging, 0, "Log failed authorization requests");
104
105 /*
106 * This tunable is here for compatibility. It will allow the user to switch
107 * between the new mode (first rule matches) and the old functionality (all
108 * rules match).
109 */
110 static int ugidfw_firstmatch_enabled;
111 SYSCTL_INT(_security_mac_bsdextended, OID_AUTO, firstmatch_enabled,
112 CTLFLAG_RW, &ugidfw_firstmatch_enabled, 1,
113 "Disable/enable match first rule functionality");
114
115 static int
ugidfw_rule_valid(struct mac_bsdextended_rule * rule)116 ugidfw_rule_valid(struct mac_bsdextended_rule *rule)
117 {
118
119 if ((rule->mbr_subject.mbs_flags | MBS_ALL_FLAGS) != MBS_ALL_FLAGS)
120 return (EINVAL);
121 if ((rule->mbr_subject.mbs_neg | MBS_ALL_FLAGS) != MBS_ALL_FLAGS)
122 return (EINVAL);
123 if ((rule->mbr_object.mbo_flags | MBO_ALL_FLAGS) != MBO_ALL_FLAGS)
124 return (EINVAL);
125 if ((rule->mbr_object.mbo_neg | MBO_ALL_FLAGS) != MBO_ALL_FLAGS)
126 return (EINVAL);
127 if (((rule->mbr_object.mbo_flags & MBO_TYPE_DEFINED) != 0) &&
128 (rule->mbr_object.mbo_type | MBO_ALL_TYPE) != MBO_ALL_TYPE)
129 return (EINVAL);
130 if ((rule->mbr_mode | MBI_ALLPERM) != MBI_ALLPERM)
131 return (EINVAL);
132 return (0);
133 }
134
135 static int
sysctl_rule(SYSCTL_HANDLER_ARGS)136 sysctl_rule(SYSCTL_HANDLER_ARGS)
137 {
138 struct mac_bsdextended_rule temprule, *ruleptr;
139 u_int namelen;
140 int error, index, *name;
141
142 error = 0;
143 name = (int *)arg1;
144 namelen = arg2;
145 if (namelen != 1)
146 return (EINVAL);
147 index = name[0];
148 if (index >= MAC_BSDEXTENDED_MAXRULES)
149 return (ENOENT);
150
151 ruleptr = NULL;
152 if (req->newptr && req->newlen != 0) {
153 error = SYSCTL_IN(req, &temprule, sizeof(temprule));
154 if (error)
155 return (error);
156 ruleptr = malloc(sizeof(*ruleptr), M_MACBSDEXTENDED,
157 M_WAITOK | M_ZERO);
158 }
159
160 mtx_lock(&ugidfw_mtx);
161 if (req->oldptr) {
162 if (index < 0 || index > rule_slots + 1) {
163 error = ENOENT;
164 goto out;
165 }
166 if (rules[index] == NULL) {
167 error = ENOENT;
168 goto out;
169 }
170 temprule = *rules[index];
171 }
172 if (req->newptr && req->newlen == 0) {
173 KASSERT(ruleptr == NULL, ("sysctl_rule: ruleptr != NULL"));
174 ruleptr = rules[index];
175 if (ruleptr == NULL) {
176 error = ENOENT;
177 goto out;
178 }
179 rule_count--;
180 rules[index] = NULL;
181 } else if (req->newptr) {
182 error = ugidfw_rule_valid(&temprule);
183 if (error)
184 goto out;
185 if (rules[index] == NULL) {
186 *ruleptr = temprule;
187 rules[index] = ruleptr;
188 ruleptr = NULL;
189 if (index + 1 > rule_slots)
190 rule_slots = index + 1;
191 rule_count++;
192 } else
193 *rules[index] = temprule;
194 }
195 out:
196 mtx_unlock(&ugidfw_mtx);
197 if (ruleptr != NULL)
198 free(ruleptr, M_MACBSDEXTENDED);
199 if (req->oldptr && error == 0)
200 error = SYSCTL_OUT(req, &temprule, sizeof(temprule));
201 return (error);
202 }
203
204 static SYSCTL_NODE(_security_mac_bsdextended, OID_AUTO, rules,
205 CTLFLAG_MPSAFE | CTLFLAG_RW, sysctl_rule, "BSD extended MAC rules");
206
207 static void
ugidfw_init(struct mac_policy_conf * mpc)208 ugidfw_init(struct mac_policy_conf *mpc)
209 {
210
211 mtx_init(&ugidfw_mtx, "mac_bsdextended lock", NULL, MTX_DEF);
212 }
213
214 static void
ugidfw_destroy(struct mac_policy_conf * mpc)215 ugidfw_destroy(struct mac_policy_conf *mpc)
216 {
217 int i;
218
219 for (i = 0; i < MAC_BSDEXTENDED_MAXRULES; i++) {
220 if (rules[i] != NULL)
221 free(rules[i], M_MACBSDEXTENDED);
222 }
223 mtx_destroy(&ugidfw_mtx);
224 }
225
226 static int
ugidfw_rulecheck(struct mac_bsdextended_rule * rule,struct ucred * cred,struct vnode * vp,struct vattr * vap,int acc_mode)227 ugidfw_rulecheck(struct mac_bsdextended_rule *rule,
228 struct ucred *cred, struct vnode *vp, struct vattr *vap, int acc_mode)
229 {
230 int mac_granted, match, priv_granted;
231 int i;
232
233 /*
234 * Is there a subject match?
235 */
236 mtx_assert(&ugidfw_mtx, MA_OWNED);
237 if (rule->mbr_subject.mbs_flags & MBS_UID_DEFINED) {
238 match = ((cred->cr_uid <= rule->mbr_subject.mbs_uid_max &&
239 cred->cr_uid >= rule->mbr_subject.mbs_uid_min) ||
240 (cred->cr_ruid <= rule->mbr_subject.mbs_uid_max &&
241 cred->cr_ruid >= rule->mbr_subject.mbs_uid_min) ||
242 (cred->cr_svuid <= rule->mbr_subject.mbs_uid_max &&
243 cred->cr_svuid >= rule->mbr_subject.mbs_uid_min));
244 if (rule->mbr_subject.mbs_neg & MBS_UID_DEFINED)
245 match = !match;
246 if (!match)
247 return (0);
248 }
249
250 if (rule->mbr_subject.mbs_flags & MBS_GID_DEFINED) {
251 match = ((cred->cr_rgid <= rule->mbr_subject.mbs_gid_max &&
252 cred->cr_rgid >= rule->mbr_subject.mbs_gid_min) ||
253 (cred->cr_svgid <= rule->mbr_subject.mbs_gid_max &&
254 cred->cr_svgid >= rule->mbr_subject.mbs_gid_min));
255 if (!match) {
256 for (i = 0; i < cred->cr_ngroups; i++) {
257 if (cred->cr_groups[i]
258 <= rule->mbr_subject.mbs_gid_max &&
259 cred->cr_groups[i]
260 >= rule->mbr_subject.mbs_gid_min) {
261 match = 1;
262 break;
263 }
264 }
265 }
266 if (rule->mbr_subject.mbs_neg & MBS_GID_DEFINED)
267 match = !match;
268 if (!match)
269 return (0);
270 }
271
272 if (rule->mbr_subject.mbs_flags & MBS_PRISON_DEFINED) {
273 match =
274 (cred->cr_prison->pr_id == rule->mbr_subject.mbs_prison);
275 if (rule->mbr_subject.mbs_neg & MBS_PRISON_DEFINED)
276 match = !match;
277 if (!match)
278 return (0);
279 }
280
281 /*
282 * Is there an object match?
283 */
284 if (rule->mbr_object.mbo_flags & MBO_UID_DEFINED) {
285 match = (vap->va_uid <= rule->mbr_object.mbo_uid_max &&
286 vap->va_uid >= rule->mbr_object.mbo_uid_min);
287 if (rule->mbr_object.mbo_neg & MBO_UID_DEFINED)
288 match = !match;
289 if (!match)
290 return (0);
291 }
292
293 if (rule->mbr_object.mbo_flags & MBO_GID_DEFINED) {
294 match = (vap->va_gid <= rule->mbr_object.mbo_gid_max &&
295 vap->va_gid >= rule->mbr_object.mbo_gid_min);
296 if (rule->mbr_object.mbo_neg & MBO_GID_DEFINED)
297 match = !match;
298 if (!match)
299 return (0);
300 }
301
302 if (rule->mbr_object.mbo_flags & MBO_FSID_DEFINED) {
303 match = (fsidcmp(&vp->v_mount->mnt_stat.f_fsid,
304 &rule->mbr_object.mbo_fsid) == 0);
305 if (rule->mbr_object.mbo_neg & MBO_FSID_DEFINED)
306 match = !match;
307 if (!match)
308 return (0);
309 }
310
311 if (rule->mbr_object.mbo_flags & MBO_SUID) {
312 match = (vap->va_mode & S_ISUID);
313 if (rule->mbr_object.mbo_neg & MBO_SUID)
314 match = !match;
315 if (!match)
316 return (0);
317 }
318
319 if (rule->mbr_object.mbo_flags & MBO_SGID) {
320 match = (vap->va_mode & S_ISGID);
321 if (rule->mbr_object.mbo_neg & MBO_SGID)
322 match = !match;
323 if (!match)
324 return (0);
325 }
326
327 if (rule->mbr_object.mbo_flags & MBO_UID_SUBJECT) {
328 match = (vap->va_uid == cred->cr_uid ||
329 vap->va_uid == cred->cr_ruid ||
330 vap->va_uid == cred->cr_svuid);
331 if (rule->mbr_object.mbo_neg & MBO_UID_SUBJECT)
332 match = !match;
333 if (!match)
334 return (0);
335 }
336
337 if (rule->mbr_object.mbo_flags & MBO_GID_SUBJECT) {
338 match = (groupmember(vap->va_gid, cred) ||
339 vap->va_gid == cred->cr_rgid ||
340 vap->va_gid == cred->cr_svgid);
341 if (rule->mbr_object.mbo_neg & MBO_GID_SUBJECT)
342 match = !match;
343 if (!match)
344 return (0);
345 }
346
347 if (rule->mbr_object.mbo_flags & MBO_TYPE_DEFINED) {
348 switch (vap->va_type) {
349 case VREG:
350 match = (rule->mbr_object.mbo_type & MBO_TYPE_REG);
351 break;
352 case VDIR:
353 match = (rule->mbr_object.mbo_type & MBO_TYPE_DIR);
354 break;
355 case VBLK:
356 match = (rule->mbr_object.mbo_type & MBO_TYPE_BLK);
357 break;
358 case VCHR:
359 match = (rule->mbr_object.mbo_type & MBO_TYPE_CHR);
360 break;
361 case VLNK:
362 match = (rule->mbr_object.mbo_type & MBO_TYPE_LNK);
363 break;
364 case VSOCK:
365 match = (rule->mbr_object.mbo_type & MBO_TYPE_SOCK);
366 break;
367 case VFIFO:
368 match = (rule->mbr_object.mbo_type & MBO_TYPE_FIFO);
369 break;
370 default:
371 match = 0;
372 }
373 if (rule->mbr_object.mbo_neg & MBO_TYPE_DEFINED)
374 match = !match;
375 if (!match)
376 return (0);
377 }
378
379 /*
380 * MBI_APPEND should not be here as it should get converted to
381 * MBI_WRITE.
382 */
383 priv_granted = 0;
384 mac_granted = rule->mbr_mode;
385 if ((acc_mode & MBI_ADMIN) && (mac_granted & MBI_ADMIN) == 0 &&
386 priv_check_cred(cred, PRIV_VFS_ADMIN) == 0)
387 priv_granted |= MBI_ADMIN;
388 if ((acc_mode & MBI_EXEC) && (mac_granted & MBI_EXEC) == 0 &&
389 priv_check_cred(cred, (vap->va_type == VDIR) ? PRIV_VFS_LOOKUP : PRIV_VFS_EXEC) == 0)
390 priv_granted |= MBI_EXEC;
391 if ((acc_mode & MBI_READ) && (mac_granted & MBI_READ) == 0 &&
392 priv_check_cred(cred, PRIV_VFS_READ) == 0)
393 priv_granted |= MBI_READ;
394 if ((acc_mode & MBI_STAT) && (mac_granted & MBI_STAT) == 0 &&
395 priv_check_cred(cred, PRIV_VFS_STAT) == 0)
396 priv_granted |= MBI_STAT;
397 if ((acc_mode & MBI_WRITE) && (mac_granted & MBI_WRITE) == 0 &&
398 priv_check_cred(cred, PRIV_VFS_WRITE) == 0)
399 priv_granted |= MBI_WRITE;
400 /*
401 * Is the access permitted?
402 */
403 if (((mac_granted | priv_granted) & acc_mode) != acc_mode) {
404 if (ugidfw_logging)
405 log(LOG_AUTHPRIV, "mac_bsdextended: %d:%d request %d"
406 " on %d:%d failed. \n", cred->cr_ruid,
407 cred->cr_rgid, acc_mode, vap->va_uid,
408 vap->va_gid);
409 return (EACCES);
410 }
411
412 /*
413 * If the rule matched, permits access, and first match is enabled,
414 * return success.
415 */
416 if (ugidfw_firstmatch_enabled)
417 return (EJUSTRETURN);
418 else
419 return (0);
420 }
421
422 int
ugidfw_check(struct ucred * cred,struct vnode * vp,struct vattr * vap,int acc_mode)423 ugidfw_check(struct ucred *cred, struct vnode *vp, struct vattr *vap,
424 int acc_mode)
425 {
426 int error, i;
427
428 /*
429 * Since we do not separately handle append, map append to write.
430 */
431 if (acc_mode & MBI_APPEND) {
432 acc_mode &= ~MBI_APPEND;
433 acc_mode |= MBI_WRITE;
434 }
435 mtx_lock(&ugidfw_mtx);
436 for (i = 0; i < rule_slots; i++) {
437 if (rules[i] == NULL)
438 continue;
439 error = ugidfw_rulecheck(rules[i], cred,
440 vp, vap, acc_mode);
441 if (error == EJUSTRETURN)
442 break;
443 if (error) {
444 mtx_unlock(&ugidfw_mtx);
445 return (error);
446 }
447 }
448 mtx_unlock(&ugidfw_mtx);
449 return (0);
450 }
451
452 int
ugidfw_check_vp(struct ucred * cred,struct vnode * vp,int acc_mode)453 ugidfw_check_vp(struct ucred *cred, struct vnode *vp, int acc_mode)
454 {
455 int error;
456 struct vattr vap;
457
458 if (!ugidfw_enabled)
459 return (0);
460 error = VOP_GETATTR(vp, &vap, cred);
461 if (error)
462 return (error);
463 return (ugidfw_check(cred, vp, &vap, acc_mode));
464 }
465
466 int
ugidfw_accmode2mbi(accmode_t accmode)467 ugidfw_accmode2mbi(accmode_t accmode)
468 {
469 int mbi;
470
471 mbi = 0;
472 if (accmode & VEXEC)
473 mbi |= MBI_EXEC;
474 if (accmode & VWRITE)
475 mbi |= MBI_WRITE;
476 if (accmode & VREAD)
477 mbi |= MBI_READ;
478 if (accmode & VADMIN_PERMS)
479 mbi |= MBI_ADMIN;
480 if (accmode & VSTAT_PERMS)
481 mbi |= MBI_STAT;
482 if (accmode & VAPPEND)
483 mbi |= MBI_APPEND;
484 return (mbi);
485 }
486
487 static struct mac_policy_ops ugidfw_ops =
488 {
489 .mpo_destroy = ugidfw_destroy,
490 .mpo_init = ugidfw_init,
491 .mpo_system_check_acct = ugidfw_system_check_acct,
492 .mpo_system_check_auditctl = ugidfw_system_check_auditctl,
493 .mpo_system_check_swapon = ugidfw_system_check_swapon,
494 .mpo_vnode_check_access = ugidfw_vnode_check_access,
495 .mpo_vnode_check_chdir = ugidfw_vnode_check_chdir,
496 .mpo_vnode_check_chroot = ugidfw_vnode_check_chroot,
497 .mpo_vnode_check_create = ugidfw_check_create_vnode,
498 .mpo_vnode_check_deleteacl = ugidfw_vnode_check_deleteacl,
499 .mpo_vnode_check_deleteextattr = ugidfw_vnode_check_deleteextattr,
500 .mpo_vnode_check_exec = ugidfw_vnode_check_exec,
501 .mpo_vnode_check_getacl = ugidfw_vnode_check_getacl,
502 .mpo_vnode_check_getextattr = ugidfw_vnode_check_getextattr,
503 .mpo_vnode_check_link = ugidfw_vnode_check_link,
504 .mpo_vnode_check_listextattr = ugidfw_vnode_check_listextattr,
505 .mpo_vnode_check_lookup = ugidfw_vnode_check_lookup,
506 .mpo_vnode_check_open = ugidfw_vnode_check_open,
507 .mpo_vnode_check_readdir = ugidfw_vnode_check_readdir,
508 .mpo_vnode_check_readlink = ugidfw_vnode_check_readdlink,
509 .mpo_vnode_check_rename_from = ugidfw_vnode_check_rename_from,
510 .mpo_vnode_check_rename_to = ugidfw_vnode_check_rename_to,
511 .mpo_vnode_check_revoke = ugidfw_vnode_check_revoke,
512 .mpo_vnode_check_setacl = ugidfw_check_setacl_vnode,
513 .mpo_vnode_check_setextattr = ugidfw_vnode_check_setextattr,
514 .mpo_vnode_check_setflags = ugidfw_vnode_check_setflags,
515 .mpo_vnode_check_setmode = ugidfw_vnode_check_setmode,
516 .mpo_vnode_check_setowner = ugidfw_vnode_check_setowner,
517 .mpo_vnode_check_setutimes = ugidfw_vnode_check_setutimes,
518 .mpo_vnode_check_stat = ugidfw_vnode_check_stat,
519 .mpo_vnode_check_unlink = ugidfw_vnode_check_unlink,
520 };
521
522 MAC_POLICY_SET(&ugidfw_ops, mac_bsdextended, "TrustedBSD MAC/BSD Extended",
523 MPC_LOADTIME_FLAG_UNLOADOK, NULL);
524