1 /*-
2 * Copyright (c) 2007 Pawel Jakub Dawidek <pjd@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
29
30 #include <sys/param.h>
31 #include <sys/priv.h>
32 #include <sys/vnode.h>
33 #include <sys/mntent.h>
34 #include <sys/mount.h>
35 #include <sys/stat.h>
36 #include <sys/jail.h>
37 #include <sys/policy.h>
38 #include <sys/zfs_vfsops.h>
39
40 int
secpolicy_nfs(cred_t * cr)41 secpolicy_nfs(cred_t *cr)
42 {
43
44 return (priv_check_cred(cr, PRIV_NFS_DAEMON, 0));
45 }
46
47 int
secpolicy_zfs(cred_t * cr)48 secpolicy_zfs(cred_t *cr)
49 {
50
51 return (priv_check_cred(cr, PRIV_VFS_MOUNT, 0));
52 }
53
54 int
secpolicy_sys_config(cred_t * cr,int checkonly __unused)55 secpolicy_sys_config(cred_t *cr, int checkonly __unused)
56 {
57
58 return (priv_check_cred(cr, PRIV_ZFS_POOL_CONFIG, 0));
59 }
60
61 int
secpolicy_zinject(cred_t * cr)62 secpolicy_zinject(cred_t *cr)
63 {
64
65 return (priv_check_cred(cr, PRIV_ZFS_INJECT, 0));
66 }
67
68 int
secpolicy_fs_unmount(cred_t * cr,struct mount * vfsp __unused)69 secpolicy_fs_unmount(cred_t *cr, struct mount *vfsp __unused)
70 {
71
72 return (priv_check_cred(cr, PRIV_VFS_UNMOUNT, 0));
73 }
74
75 int
secpolicy_fs_owner(struct mount * mp,cred_t * cr)76 secpolicy_fs_owner(struct mount *mp, cred_t *cr)
77 {
78
79 if (zfs_super_owner) {
80 if (cr->cr_uid == mp->mnt_cred->cr_uid &&
81 cr->cr_prison == mp->mnt_cred->cr_prison) {
82 return (0);
83 }
84 }
85 return (EPERM);
86 }
87
88 /*
89 * This check is done in kern_link(), so we could just return 0 here.
90 */
91 extern int hardlink_check_uid;
92 int
secpolicy_basic_link(vnode_t * vp,cred_t * cr)93 secpolicy_basic_link(vnode_t *vp, cred_t *cr)
94 {
95
96 if (!hardlink_check_uid)
97 return (0);
98 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
99 return (0);
100 return (priv_check_cred(cr, PRIV_VFS_LINK, 0));
101 }
102
103 int
secpolicy_vnode_stky_modify(cred_t * cr)104 secpolicy_vnode_stky_modify(cred_t *cr)
105 {
106
107 return (EPERM);
108 }
109
110 int
secpolicy_vnode_remove(vnode_t * vp,cred_t * cr)111 secpolicy_vnode_remove(vnode_t *vp, cred_t *cr)
112 {
113
114 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
115 return (0);
116 return (priv_check_cred(cr, PRIV_VFS_ADMIN, 0));
117 }
118
119 int
secpolicy_vnode_access(cred_t * cr,vnode_t * vp,uid_t owner,accmode_t accmode)120 secpolicy_vnode_access(cred_t *cr, vnode_t *vp, uid_t owner, accmode_t accmode)
121 {
122
123 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
124 return (0);
125
126 if ((accmode & VREAD) && priv_check_cred(cr, PRIV_VFS_READ, 0) != 0)
127 return (EACCES);
128 if ((accmode & VWRITE) &&
129 priv_check_cred(cr, PRIV_VFS_WRITE, 0) != 0) {
130 return (EACCES);
131 }
132 if (accmode & VEXEC) {
133 if (vp->v_type == VDIR) {
134 if (priv_check_cred(cr, PRIV_VFS_LOOKUP, 0) != 0)
135 return (EACCES);
136 } else {
137 if (priv_check_cred(cr, PRIV_VFS_EXEC, 0) != 0)
138 return (EACCES);
139 }
140 }
141 return (0);
142 }
143
144 /*
145 * Like secpolicy_vnode_access() but we get the actual wanted mode and the
146 * current mode of the file, not the missing bits.
147 */
148 int
secpolicy_vnode_access2(cred_t * cr,vnode_t * vp,uid_t owner,accmode_t curmode,accmode_t wantmode)149 secpolicy_vnode_access2(cred_t *cr, vnode_t *vp, uid_t owner,
150 accmode_t curmode, accmode_t wantmode)
151 {
152 accmode_t mode;
153
154 mode = ~curmode & wantmode;
155
156 if (mode == 0)
157 return (0);
158
159 return (secpolicy_vnode_access(cr, vp, owner, mode));
160 }
161
162 int
secpolicy_vnode_any_access(cred_t * cr,vnode_t * vp,uid_t owner)163 secpolicy_vnode_any_access(cred_t *cr, vnode_t *vp, uid_t owner)
164 {
165 static int privs[] = {
166 PRIV_VFS_ADMIN,
167 PRIV_VFS_READ,
168 PRIV_VFS_WRITE,
169 PRIV_VFS_EXEC,
170 PRIV_VFS_LOOKUP
171 };
172 int i;
173
174 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
175 return (0);
176
177 /* Same as secpolicy_vnode_setdac */
178 if (owner == cr->cr_uid)
179 return (0);
180
181 for (i = 0; i < sizeof (privs)/sizeof (int); i++) {
182 boolean_t allzone = B_FALSE;
183 int priv;
184
185 switch (priv = privs[i]) {
186 case PRIV_VFS_EXEC:
187 if (vp->v_type == VDIR)
188 continue;
189 break;
190 case PRIV_VFS_LOOKUP:
191 if (vp->v_type != VDIR)
192 continue;
193 break;
194 }
195 if (priv_check_cred(cr, priv, 0) == 0)
196 return (0);
197 }
198 return (EPERM);
199 }
200
201 int
secpolicy_vnode_setdac(vnode_t * vp,cred_t * cr,uid_t owner)202 secpolicy_vnode_setdac(vnode_t *vp, cred_t *cr, uid_t owner)
203 {
204
205 if (owner == cr->cr_uid)
206 return (0);
207 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
208 return (0);
209 return (priv_check_cred(cr, PRIV_VFS_ADMIN, 0));
210 }
211
212 int
secpolicy_vnode_setattr(cred_t * cr,vnode_t * vp,struct vattr * vap,const struct vattr * ovap,int flags,int unlocked_access (void *,int,cred_t *),void * node)213 secpolicy_vnode_setattr(cred_t *cr, vnode_t *vp, struct vattr *vap,
214 const struct vattr *ovap, int flags,
215 int unlocked_access(void *, int, cred_t *), void *node)
216 {
217 int mask = vap->va_mask;
218 int error;
219
220 if (mask & AT_SIZE) {
221 if (vp->v_type == VDIR)
222 return (EISDIR);
223 error = unlocked_access(node, VWRITE, cr);
224 if (error)
225 return (error);
226 }
227 if (mask & AT_MODE) {
228 /*
229 * If not the owner of the file then check privilege
230 * for two things: the privilege to set the mode at all
231 * and, if we're setting setuid, we also need permissions
232 * to add the set-uid bit, if we're not the owner.
233 * In the specific case of creating a set-uid root
234 * file, we need even more permissions.
235 */
236 error = secpolicy_vnode_setdac(vp, cr, ovap->va_uid);
237 if (error)
238 return (error);
239 error = secpolicy_setid_setsticky_clear(vp, vap, ovap, cr);
240 if (error)
241 return (error);
242 } else {
243 vap->va_mode = ovap->va_mode;
244 }
245 if (mask & (AT_UID | AT_GID)) {
246 error = secpolicy_vnode_setdac(vp, cr, ovap->va_uid);
247 if (error)
248 return (error);
249
250 /*
251 * To change the owner of a file, or change the group of a file to a
252 * group of which we are not a member, the caller must have
253 * privilege.
254 */
255 if (((mask & AT_UID) && vap->va_uid != ovap->va_uid) ||
256 ((mask & AT_GID) && vap->va_gid != ovap->va_gid &&
257 !groupmember(vap->va_gid, cr))) {
258 if (secpolicy_fs_owner(vp->v_mount, cr) != 0) {
259 error = priv_check_cred(cr, PRIV_VFS_CHOWN, 0);
260 if (error)
261 return (error);
262 }
263 }
264
265 if (((mask & AT_UID) && vap->va_uid != ovap->va_uid) ||
266 ((mask & AT_GID) && vap->va_gid != ovap->va_gid)) {
267 secpolicy_setid_clear(vap, vp, cr);
268 }
269 }
270 if (mask & (AT_ATIME | AT_MTIME)) {
271 /*
272 * From utimes(2):
273 * If times is NULL, ... The caller must be the owner of
274 * the file, have permission to write the file, or be the
275 * super-user.
276 * If times is non-NULL, ... The caller must be the owner of
277 * the file or be the super-user.
278 */
279 error = secpolicy_vnode_setdac(vp, cr, ovap->va_uid);
280 if (error && (vap->va_vaflags & VA_UTIMES_NULL))
281 error = unlocked_access(node, VWRITE, cr);
282 if (error)
283 return (error);
284 }
285 return (0);
286 }
287
288 int
secpolicy_vnode_create_gid(cred_t * cr)289 secpolicy_vnode_create_gid(cred_t *cr)
290 {
291
292 return (EPERM);
293 }
294
295 int
secpolicy_vnode_setids_setgids(vnode_t * vp,cred_t * cr,gid_t gid)296 secpolicy_vnode_setids_setgids(vnode_t *vp, cred_t *cr, gid_t gid)
297 {
298
299 if (groupmember(gid, cr))
300 return (0);
301 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
302 return (0);
303 return (priv_check_cred(cr, PRIV_VFS_SETGID, 0));
304 }
305
306 int
secpolicy_vnode_setid_retain(vnode_t * vp,cred_t * cr,boolean_t issuidroot __unused)307 secpolicy_vnode_setid_retain(vnode_t *vp, cred_t *cr,
308 boolean_t issuidroot __unused)
309 {
310
311 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
312 return (0);
313 return (priv_check_cred(cr, PRIV_VFS_RETAINSUGID, 0));
314 }
315
316 void
secpolicy_setid_clear(struct vattr * vap,vnode_t * vp,cred_t * cr)317 secpolicy_setid_clear(struct vattr *vap, vnode_t *vp, cred_t *cr)
318 {
319
320 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
321 return;
322
323 if ((vap->va_mode & (S_ISUID | S_ISGID)) != 0) {
324 if (priv_check_cred(cr, PRIV_VFS_RETAINSUGID, 0)) {
325 vap->va_mask |= AT_MODE;
326 vap->va_mode &= ~(S_ISUID|S_ISGID);
327 }
328 }
329 }
330
331 int
secpolicy_setid_setsticky_clear(vnode_t * vp,struct vattr * vap,const struct vattr * ovap,cred_t * cr)332 secpolicy_setid_setsticky_clear(vnode_t *vp, struct vattr *vap,
333 const struct vattr *ovap, cred_t *cr)
334 {
335 int error;
336
337 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
338 return (0);
339
340 /*
341 * Privileged processes may set the sticky bit on non-directories,
342 * as well as set the setgid bit on a file with a group that the process
343 * is not a member of. Both of these are allowed in jail(8).
344 */
345 if (vp->v_type != VDIR && (vap->va_mode & S_ISTXT)) {
346 if (priv_check_cred(cr, PRIV_VFS_STICKYFILE, 0))
347 return (EFTYPE);
348 }
349 /*
350 * Check for privilege if attempting to set the
351 * group-id bit.
352 */
353 if ((vap->va_mode & S_ISGID) != 0) {
354 error = secpolicy_vnode_setids_setgids(vp, cr, ovap->va_gid);
355 if (error)
356 return (error);
357 }
358 /*
359 * Deny setting setuid if we are not the file owner.
360 */
361 if ((vap->va_mode & S_ISUID) && ovap->va_uid != cr->cr_uid) {
362 error = priv_check_cred(cr, PRIV_VFS_ADMIN, 0);
363 if (error)
364 return (error);
365 }
366 return (0);
367 }
368
369 int
secpolicy_fs_mount(cred_t * cr,vnode_t * mvp,struct mount * vfsp)370 secpolicy_fs_mount(cred_t *cr, vnode_t *mvp, struct mount *vfsp)
371 {
372
373 return (priv_check_cred(cr, PRIV_VFS_MOUNT, 0));
374 }
375
376 int
secpolicy_vnode_owner(vnode_t * vp,cred_t * cr,uid_t owner)377 secpolicy_vnode_owner(vnode_t *vp, cred_t *cr, uid_t owner)
378 {
379
380 if (owner == cr->cr_uid)
381 return (0);
382 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
383 return (0);
384
385 /* XXX: vfs_suser()? */
386 return (priv_check_cred(cr, PRIV_VFS_MOUNT_OWNER, 0));
387 }
388
389 int
secpolicy_vnode_chown(vnode_t * vp,cred_t * cr,uid_t owner)390 secpolicy_vnode_chown(vnode_t *vp, cred_t *cr, uid_t owner)
391 {
392
393 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
394 return (0);
395 return (priv_check_cred(cr, PRIV_VFS_CHOWN, 0));
396 }
397
398 void
secpolicy_fs_mount_clearopts(cred_t * cr,struct mount * vfsp)399 secpolicy_fs_mount_clearopts(cred_t *cr, struct mount *vfsp)
400 {
401
402 if (priv_check_cred(cr, PRIV_VFS_MOUNT_NONUSER, 0) != 0) {
403 MNT_ILOCK(vfsp);
404 vfsp->vfs_flag |= VFS_NOSETUID | MNT_USER;
405 vfs_clearmntopt(vfsp, MNTOPT_SETUID);
406 vfs_setmntopt(vfsp, MNTOPT_NOSETUID, NULL, 0);
407 MNT_IUNLOCK(vfsp);
408 }
409 }
410
411 /*
412 * Check privileges for setting xvattr attributes
413 */
414 int
secpolicy_xvattr(vnode_t * vp,xvattr_t * xvap,uid_t owner,cred_t * cr,vtype_t vtype)415 secpolicy_xvattr(vnode_t *vp, xvattr_t *xvap, uid_t owner, cred_t *cr,
416 vtype_t vtype)
417 {
418
419 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
420 return (0);
421 return (priv_check_cred(cr, PRIV_VFS_SYSFLAGS, 0));
422 }
423
424 int
secpolicy_smb(cred_t * cr)425 secpolicy_smb(cred_t *cr)
426 {
427
428 return (priv_check_cred(cr, PRIV_NETSMB, 0));
429 }
430