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/types.h>
28 #include <sys/param.h>
29 #include <sys/priv.h>
30 #include <sys/vnode.h>
31 #include <sys/mntent.h>
32 #include <sys/mount.h>
33 #include <sys/stat.h>
34 #include <sys/jail.h>
35 #include <sys/policy.h>
36 #include <sys/zfs_vfsops.h>
37 #include <sys/zfs_znode.h>
38
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));
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));
52 }
53
54 int
secpolicy_zfs_proc(cred_t * cr,proc_t * proc)55 secpolicy_zfs_proc(cred_t *cr, proc_t *proc)
56 {
57
58 return (priv_check_cred(cr, PRIV_VFS_MOUNT));
59 }
60
61 int
secpolicy_sys_config(cred_t * cr,int checkonly __unused)62 secpolicy_sys_config(cred_t *cr, int checkonly __unused)
63 {
64
65 return (priv_check_cred(cr, PRIV_ZFS_POOL_CONFIG));
66 }
67
68 int
secpolicy_zinject(cred_t * cr)69 secpolicy_zinject(cred_t *cr)
70 {
71
72 return (priv_check_cred(cr, PRIV_ZFS_INJECT));
73 }
74
75 int
secpolicy_fs_unmount(cred_t * cr,struct mount * vfsp __unused)76 secpolicy_fs_unmount(cred_t *cr, struct mount *vfsp __unused)
77 {
78
79 return (priv_check_cred(cr, PRIV_VFS_UNMOUNT));
80 }
81
82 int
secpolicy_fs_owner(struct mount * mp,cred_t * cr)83 secpolicy_fs_owner(struct mount *mp, cred_t *cr)
84 {
85
86 if (zfs_super_owner) {
87 if (cr->cr_uid == mp->mnt_cred->cr_uid &&
88 cr->cr_prison == mp->mnt_cred->cr_prison) {
89 return (0);
90 }
91 }
92 return (EPERM);
93 }
94
95 /*
96 * This check is done in kern_link(), so we could just return 0 here.
97 */
98 extern int hardlink_check_uid;
99 int
secpolicy_basic_link(vnode_t * vp,cred_t * cr)100 secpolicy_basic_link(vnode_t *vp, cred_t *cr)
101 {
102
103 if (!hardlink_check_uid)
104 return (0);
105 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
106 return (0);
107 return (priv_check_cred(cr, PRIV_VFS_LINK));
108 }
109
110 int
secpolicy_vnode_stky_modify(cred_t * cr)111 secpolicy_vnode_stky_modify(cred_t *cr)
112 {
113
114 return (EPERM);
115 }
116
117 int
secpolicy_vnode_remove(vnode_t * vp,cred_t * cr)118 secpolicy_vnode_remove(vnode_t *vp, cred_t *cr)
119 {
120
121 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
122 return (0);
123 return (priv_check_cred(cr, PRIV_VFS_ADMIN));
124 }
125
126 int
secpolicy_vnode_access(cred_t * cr,vnode_t * vp,uid_t owner,accmode_t accmode)127 secpolicy_vnode_access(cred_t *cr, vnode_t *vp, uid_t owner, accmode_t accmode)
128 {
129
130 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
131 return (0);
132
133 if ((accmode & VREAD) && priv_check_cred(cr, PRIV_VFS_READ) != 0)
134 return (EACCES);
135 if ((accmode & VWRITE) &&
136 priv_check_cred(cr, PRIV_VFS_WRITE) != 0) {
137 return (EACCES);
138 }
139 if (accmode & VEXEC) {
140 if (vp->v_type == VDIR) {
141 if (priv_check_cred(cr, PRIV_VFS_LOOKUP) != 0)
142 return (EACCES);
143 } else {
144 if (priv_check_cred(cr, PRIV_VFS_EXEC) != 0)
145 return (EACCES);
146 }
147 }
148 return (0);
149 }
150
151 /*
152 * Like secpolicy_vnode_access() but we get the actual wanted mode and the
153 * current mode of the file, not the missing bits.
154 */
155 int
secpolicy_vnode_access2(cred_t * cr,vnode_t * vp,uid_t owner,accmode_t curmode,accmode_t wantmode)156 secpolicy_vnode_access2(cred_t *cr, vnode_t *vp, uid_t owner,
157 accmode_t curmode, accmode_t wantmode)
158 {
159 accmode_t mode;
160
161 mode = ~curmode & wantmode;
162
163 if (mode == 0)
164 return (0);
165
166 return (secpolicy_vnode_access(cr, vp, owner, mode));
167 }
168
169 int
secpolicy_vnode_any_access(cred_t * cr,vnode_t * vp,uid_t owner)170 secpolicy_vnode_any_access(cred_t *cr, vnode_t *vp, uid_t owner)
171 {
172 static int privs[] = {
173 PRIV_VFS_ADMIN,
174 PRIV_VFS_READ,
175 PRIV_VFS_WRITE,
176 PRIV_VFS_EXEC,
177 PRIV_VFS_LOOKUP
178 };
179 int i;
180
181 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
182 return (0);
183
184 /* Same as secpolicy_vnode_setdac */
185 if (owner == cr->cr_uid)
186 return (0);
187
188 for (i = 0; i < sizeof (privs)/sizeof (int); i++) {
189 int priv;
190
191 switch (priv = privs[i]) {
192 case PRIV_VFS_EXEC:
193 if (vp->v_type == VDIR)
194 continue;
195 break;
196 case PRIV_VFS_LOOKUP:
197 if (vp->v_type != VDIR)
198 continue;
199 break;
200 }
201 if (priv_check_cred(cr, priv) == 0)
202 return (0);
203 }
204 return (EPERM);
205 }
206
207 int
secpolicy_vnode_setdac(vnode_t * vp,cred_t * cr,uid_t owner)208 secpolicy_vnode_setdac(vnode_t *vp, cred_t *cr, uid_t owner)
209 {
210
211 if (owner == cr->cr_uid)
212 return (0);
213 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
214 return (0);
215 return (priv_check_cred(cr, PRIV_VFS_ADMIN));
216 }
217
218 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)219 secpolicy_vnode_setattr(cred_t *cr, vnode_t *vp, struct vattr *vap,
220 const struct vattr *ovap, int flags,
221 int unlocked_access(void *, int, cred_t *), void *node)
222 {
223 int mask = vap->va_mask;
224 int error;
225
226 if (mask & AT_SIZE) {
227 if (vp->v_type == VDIR)
228 return (EISDIR);
229 error = unlocked_access(node, VWRITE, cr);
230 if (error)
231 return (error);
232 }
233 if (mask & AT_MODE) {
234 /*
235 * If not the owner of the file then check privilege
236 * for two things: the privilege to set the mode at all
237 * and, if we're setting setuid, we also need permissions
238 * to add the set-uid bit, if we're not the owner.
239 * In the specific case of creating a set-uid root
240 * file, we need even more permissions.
241 */
242 error = secpolicy_vnode_setdac(vp, cr, ovap->va_uid);
243 if (error)
244 return (error);
245 error = secpolicy_setid_setsticky_clear(vp, vap, ovap, cr);
246 if (error)
247 return (error);
248 } else {
249 vap->va_mode = ovap->va_mode;
250 }
251 if (mask & (AT_UID | AT_GID)) {
252 error = secpolicy_vnode_setdac(vp, cr, ovap->va_uid);
253 if (error)
254 return (error);
255
256 /*
257 * To change the owner of a file, or change the group of
258 * a file to a group of which we are not a member, the
259 * caller must have privilege.
260 */
261 if (((mask & AT_UID) && vap->va_uid != ovap->va_uid) ||
262 ((mask & AT_GID) && vap->va_gid != ovap->va_gid &&
263 !groupmember(vap->va_gid, cr))) {
264 if (secpolicy_fs_owner(vp->v_mount, cr) != 0) {
265 error = priv_check_cred(cr, PRIV_VFS_CHOWN);
266 if (error)
267 return (error);
268 }
269 }
270
271 if (((mask & AT_UID) && vap->va_uid != ovap->va_uid) ||
272 ((mask & AT_GID) && vap->va_gid != ovap->va_gid)) {
273 secpolicy_setid_clear(vap, vp, cr);
274 }
275 }
276 if (mask & (AT_ATIME | AT_MTIME)) {
277 /*
278 * From utimes(2):
279 * If times is NULL, ... The caller must be the owner of
280 * the file, have permission to write the file, or be the
281 * super-user.
282 * If times is non-NULL, ... The caller must be the owner of
283 * the file or be the super-user.
284 */
285 error = secpolicy_vnode_setdac(vp, cr, ovap->va_uid);
286 if (error && (vap->va_vaflags & VA_UTIMES_NULL))
287 error = unlocked_access(node, VWRITE, cr);
288 if (error)
289 return (error);
290 }
291 return (0);
292 }
293
294 int
secpolicy_vnode_create_gid(cred_t * cr)295 secpolicy_vnode_create_gid(cred_t *cr)
296 {
297
298 return (EPERM);
299 }
300
301 int
secpolicy_vnode_setids_setgids(vnode_t * vp,cred_t * cr,gid_t gid)302 secpolicy_vnode_setids_setgids(vnode_t *vp, cred_t *cr, gid_t gid)
303 {
304
305 if (groupmember(gid, cr))
306 return (0);
307 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
308 return (0);
309 return (priv_check_cred(cr, PRIV_VFS_SETGID));
310 }
311
312 int
secpolicy_vnode_setid_retain(znode_t * zp,cred_t * cr,boolean_t issuidroot __unused)313 secpolicy_vnode_setid_retain(znode_t *zp, cred_t *cr,
314 boolean_t issuidroot __unused)
315 {
316
317 if (secpolicy_fs_owner(ZTOV(zp)->v_mount, cr) == 0)
318 return (0);
319 return (priv_check_cred(cr, PRIV_VFS_RETAINSUGID));
320 }
321
322 void
secpolicy_setid_clear(struct vattr * vap,vnode_t * vp,cred_t * cr)323 secpolicy_setid_clear(struct vattr *vap, vnode_t *vp, cred_t *cr)
324 {
325
326 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
327 return;
328
329 if ((vap->va_mode & (S_ISUID | S_ISGID)) != 0) {
330 if (priv_check_cred(cr, PRIV_VFS_RETAINSUGID)) {
331 vap->va_mask |= AT_MODE;
332 vap->va_mode &= ~(S_ISUID|S_ISGID);
333 }
334 }
335 }
336
337 int
secpolicy_setid_setsticky_clear(vnode_t * vp,struct vattr * vap,const struct vattr * ovap,cred_t * cr)338 secpolicy_setid_setsticky_clear(vnode_t *vp, struct vattr *vap,
339 const struct vattr *ovap, cred_t *cr)
340 {
341 int error;
342
343 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
344 return (0);
345
346 /*
347 * Privileged processes may set the sticky bit on non-directories,
348 * as well as set the setgid bit on a file with a group that the process
349 * is not a member of. Both of these are allowed in jail(8).
350 */
351 if (vp->v_type != VDIR && (vap->va_mode & S_ISTXT)) {
352 if (priv_check_cred(cr, PRIV_VFS_STICKYFILE))
353 return (EFTYPE);
354 }
355 /*
356 * Check for privilege if attempting to set the
357 * group-id bit.
358 */
359 if ((vap->va_mode & S_ISGID) != 0) {
360 error = secpolicy_vnode_setids_setgids(vp, cr, ovap->va_gid);
361 if (error)
362 return (error);
363 }
364 /*
365 * Deny setting setuid if we are not the file owner.
366 */
367 if ((vap->va_mode & S_ISUID) && ovap->va_uid != cr->cr_uid) {
368 error = priv_check_cred(cr, PRIV_VFS_ADMIN);
369 if (error)
370 return (error);
371 }
372 return (0);
373 }
374
375 int
secpolicy_fs_mount(cred_t * cr,vnode_t * mvp,struct mount * vfsp)376 secpolicy_fs_mount(cred_t *cr, vnode_t *mvp, struct mount *vfsp)
377 {
378
379 return (priv_check_cred(cr, PRIV_VFS_MOUNT));
380 }
381
382 int
secpolicy_vnode_owner(vnode_t * vp,cred_t * cr,uid_t owner)383 secpolicy_vnode_owner(vnode_t *vp, cred_t *cr, uid_t owner)
384 {
385
386 if (owner == cr->cr_uid)
387 return (0);
388 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
389 return (0);
390
391 /* XXX: vfs_suser()? */
392 return (priv_check_cred(cr, PRIV_VFS_MOUNT_OWNER));
393 }
394
395 int
secpolicy_vnode_chown(vnode_t * vp,cred_t * cr,uid_t owner)396 secpolicy_vnode_chown(vnode_t *vp, cred_t *cr, uid_t owner)
397 {
398
399 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
400 return (0);
401 return (priv_check_cred(cr, PRIV_VFS_CHOWN));
402 }
403
404 void
secpolicy_fs_mount_clearopts(cred_t * cr,struct mount * vfsp)405 secpolicy_fs_mount_clearopts(cred_t *cr, struct mount *vfsp)
406 {
407
408 if (priv_check_cred(cr, PRIV_VFS_MOUNT_NONUSER) != 0) {
409 MNT_ILOCK(vfsp);
410 vfsp->vfs_flag |= VFS_NOSETUID | MNT_USER;
411 vfs_clearmntopt(vfsp, MNTOPT_SETUID);
412 vfs_setmntopt(vfsp, MNTOPT_NOSETUID, NULL, 0);
413 MNT_IUNLOCK(vfsp);
414 }
415 }
416
417 /*
418 * Check privileges for setting xvattr attributes
419 */
420 int
secpolicy_xvattr(vnode_t * vp,xvattr_t * xvap,uid_t owner,cred_t * cr,vtype_t vtype)421 secpolicy_xvattr(vnode_t *vp, xvattr_t *xvap, uid_t owner, cred_t *cr,
422 vtype_t vtype)
423 {
424
425 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
426 return (0);
427 return (priv_check_cred(cr, PRIV_VFS_SYSFLAGS));
428 }
429
430 int
secpolicy_smb(cred_t * cr)431 secpolicy_smb(cred_t *cr)
432 {
433
434 return (priv_check_cred(cr, PRIV_NETSMB));
435 }
436