1 // SPDX-License-Identifier: BSD-2-Clause
2 /*
3 * Copyright (c) 2007 Pawel Jakub Dawidek <pjd@FreeBSD.org>
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28 #include <sys/types.h>
29 #include <sys/param.h>
30 #include <sys/priv.h>
31 #include <sys/vnode.h>
32 #include <sys/mntent.h>
33 #include <sys/mount.h>
34 #include <sys/stat.h>
35 #include <sys/jail.h>
36 #include <sys/policy.h>
37 #include <sys/zfs_vfsops.h>
38 #include <sys/zfs_znode.h>
39
40
41 int
secpolicy_nfs(cred_t * cr)42 secpolicy_nfs(cred_t *cr)
43 {
44
45 return (priv_check_cred(cr, PRIV_NFS_DAEMON));
46 }
47
48 int
secpolicy_zfs(cred_t * cr)49 secpolicy_zfs(cred_t *cr)
50 {
51
52 return (priv_check_cred(cr, PRIV_VFS_MOUNT));
53 }
54
55 int
secpolicy_zfs_proc(cred_t * cr,proc_t * proc)56 secpolicy_zfs_proc(cred_t *cr, proc_t *proc)
57 {
58
59 return (priv_check_cred(cr, PRIV_VFS_MOUNT));
60 }
61
62 int
secpolicy_sys_config(cred_t * cr,int checkonly __unused)63 secpolicy_sys_config(cred_t *cr, int checkonly __unused)
64 {
65
66 return (priv_check_cred(cr, PRIV_ZFS_POOL_CONFIG));
67 }
68
69 int
secpolicy_zinject(cred_t * cr)70 secpolicy_zinject(cred_t *cr)
71 {
72
73 return (priv_check_cred(cr, PRIV_ZFS_INJECT));
74 }
75
76 int
secpolicy_fs_unmount(cred_t * cr,struct mount * vfsp __unused)77 secpolicy_fs_unmount(cred_t *cr, struct mount *vfsp __unused)
78 {
79
80 return (priv_check_cred(cr, PRIV_VFS_UNMOUNT));
81 }
82
83 int
secpolicy_fs_owner(struct mount * mp,cred_t * cr)84 secpolicy_fs_owner(struct mount *mp, cred_t *cr)
85 {
86
87 if (zfs_super_owner) {
88 if (cr->cr_uid == mp->mnt_cred->cr_uid &&
89 cr->cr_prison == mp->mnt_cred->cr_prison) {
90 return (0);
91 }
92 }
93 return (EPERM);
94 }
95
96 /*
97 * This check is done in kern_link(), so we could just return 0 here.
98 */
99 extern int hardlink_check_uid;
100 int
secpolicy_basic_link(vnode_t * vp,cred_t * cr)101 secpolicy_basic_link(vnode_t *vp, cred_t *cr)
102 {
103
104 if (!hardlink_check_uid)
105 return (0);
106 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
107 return (0);
108 return (priv_check_cred(cr, PRIV_VFS_LINK));
109 }
110
111 int
secpolicy_vnode_stky_modify(cred_t * cr)112 secpolicy_vnode_stky_modify(cred_t *cr)
113 {
114
115 return (EPERM);
116 }
117
118 int
secpolicy_vnode_remove(vnode_t * vp,cred_t * cr)119 secpolicy_vnode_remove(vnode_t *vp, cred_t *cr)
120 {
121
122 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
123 return (0);
124 return (priv_check_cred(cr, PRIV_VFS_ADMIN));
125 }
126
127 int
secpolicy_vnode_access(cred_t * cr,vnode_t * vp,uid_t owner,accmode_t accmode)128 secpolicy_vnode_access(cred_t *cr, vnode_t *vp, uid_t owner, accmode_t accmode)
129 {
130
131 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
132 return (0);
133
134 if ((accmode & VREAD) && priv_check_cred(cr, PRIV_VFS_READ) != 0)
135 return (EACCES);
136 if ((accmode & VWRITE) &&
137 priv_check_cred(cr, PRIV_VFS_WRITE) != 0) {
138 return (EACCES);
139 }
140 if (accmode & VEXEC) {
141 if (vp->v_type == VDIR) {
142 if (priv_check_cred(cr, PRIV_VFS_LOOKUP) != 0)
143 return (EACCES);
144 } else {
145 if (priv_check_cred(cr, PRIV_VFS_EXEC) != 0)
146 return (EACCES);
147 }
148 }
149 return (0);
150 }
151
152 /*
153 * Like secpolicy_vnode_access() but we get the actual wanted mode and the
154 * current mode of the file, not the missing bits.
155 */
156 int
secpolicy_vnode_access2(cred_t * cr,vnode_t * vp,uid_t owner,accmode_t curmode,accmode_t wantmode)157 secpolicy_vnode_access2(cred_t *cr, vnode_t *vp, uid_t owner,
158 accmode_t curmode, accmode_t wantmode)
159 {
160 accmode_t mode;
161
162 mode = ~curmode & wantmode;
163
164 if (mode == 0)
165 return (0);
166
167 return (secpolicy_vnode_access(cr, vp, owner, mode));
168 }
169
170 int
secpolicy_vnode_any_access(cred_t * cr,vnode_t * vp,uid_t owner)171 secpolicy_vnode_any_access(cred_t *cr, vnode_t *vp, uid_t owner)
172 {
173 static int privs[] = {
174 PRIV_VFS_ADMIN,
175 PRIV_VFS_READ,
176 PRIV_VFS_WRITE,
177 PRIV_VFS_EXEC,
178 PRIV_VFS_LOOKUP
179 };
180 int i;
181
182 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
183 return (0);
184
185 /* Same as secpolicy_vnode_setdac */
186 if (owner == cr->cr_uid)
187 return (0);
188
189 for (i = 0; i < sizeof (privs)/sizeof (int); i++) {
190 int priv;
191
192 switch (priv = privs[i]) {
193 case PRIV_VFS_EXEC:
194 if (vp->v_type == VDIR)
195 continue;
196 break;
197 case PRIV_VFS_LOOKUP:
198 if (vp->v_type != VDIR)
199 continue;
200 break;
201 }
202 if (priv_check_cred(cr, priv) == 0)
203 return (0);
204 }
205 return (EPERM);
206 }
207
208 int
secpolicy_vnode_setdac(vnode_t * vp,cred_t * cr,uid_t owner)209 secpolicy_vnode_setdac(vnode_t *vp, cred_t *cr, uid_t owner)
210 {
211
212 if (owner == cr->cr_uid)
213 return (0);
214 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
215 return (0);
216 return (priv_check_cred(cr, PRIV_VFS_ADMIN));
217 }
218
219 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)220 secpolicy_vnode_setattr(cred_t *cr, vnode_t *vp, struct vattr *vap,
221 const struct vattr *ovap, int flags,
222 int unlocked_access(void *, int, cred_t *), void *node)
223 {
224 int mask = vap->va_mask;
225 int error;
226
227 if (mask & AT_SIZE) {
228 if (vp->v_type == VDIR)
229 return (EISDIR);
230 error = unlocked_access(node, VWRITE, cr);
231 if (error)
232 return (error);
233 }
234 if (mask & AT_MODE) {
235 /*
236 * If not the owner of the file then check privilege
237 * for two things: the privilege to set the mode at all
238 * and, if we're setting setuid, we also need permissions
239 * to add the set-uid bit, if we're not the owner.
240 * In the specific case of creating a set-uid root
241 * file, we need even more permissions.
242 */
243 error = secpolicy_vnode_setdac(vp, cr, ovap->va_uid);
244 if (error)
245 return (error);
246 error = secpolicy_setid_setsticky_clear(vp, vap, ovap, cr);
247 if (error)
248 return (error);
249 } else {
250 vap->va_mode = ovap->va_mode;
251 }
252 if (mask & (AT_UID | AT_GID)) {
253 error = secpolicy_vnode_setdac(vp, cr, ovap->va_uid);
254 if (error)
255 return (error);
256
257 /*
258 * To change the owner of a file, or change the group of
259 * a file to a group of which we are not a member, the
260 * caller must have privilege.
261 */
262 if (((mask & AT_UID) && vap->va_uid != ovap->va_uid) ||
263 ((mask & AT_GID) && vap->va_gid != ovap->va_gid &&
264 !groupmember(vap->va_gid, cr))) {
265 if (secpolicy_fs_owner(vp->v_mount, cr) != 0) {
266 error = priv_check_cred(cr, PRIV_VFS_CHOWN);
267 if (error)
268 return (error);
269 }
270 }
271
272 if (((mask & AT_UID) && vap->va_uid != ovap->va_uid) ||
273 ((mask & AT_GID) && vap->va_gid != ovap->va_gid)) {
274 secpolicy_setid_clear(vap, vp, cr);
275 }
276 }
277 if (mask & (AT_ATIME | AT_MTIME)) {
278 /*
279 * From utimes(2):
280 * If times is NULL, ... The caller must be the owner of
281 * the file, have permission to write the file, or be the
282 * super-user.
283 * If times is non-NULL, ... The caller must be the owner of
284 * the file or be the super-user.
285 */
286 error = secpolicy_vnode_setdac(vp, cr, ovap->va_uid);
287 if (error && (vap->va_vaflags & VA_UTIMES_NULL))
288 error = unlocked_access(node, VWRITE, cr);
289 if (error)
290 return (error);
291 }
292 return (0);
293 }
294
295 int
secpolicy_vnode_create_gid(cred_t * cr)296 secpolicy_vnode_create_gid(cred_t *cr)
297 {
298
299 return (EPERM);
300 }
301
302 int
secpolicy_vnode_setids_setgids(vnode_t * vp,cred_t * cr,gid_t gid)303 secpolicy_vnode_setids_setgids(vnode_t *vp, cred_t *cr, gid_t gid)
304 {
305
306 if (groupmember(gid, cr))
307 return (0);
308 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
309 return (0);
310 return (priv_check_cred(cr, PRIV_VFS_SETGID));
311 }
312
313 int
secpolicy_vnode_setid_retain(znode_t * zp,cred_t * cr,boolean_t issuidroot __unused)314 secpolicy_vnode_setid_retain(znode_t *zp, cred_t *cr,
315 boolean_t issuidroot __unused)
316 {
317
318 if (secpolicy_fs_owner(ZTOV(zp)->v_mount, cr) == 0)
319 return (0);
320 return (priv_check_cred(cr, PRIV_VFS_RETAINSUGID));
321 }
322
323 void
secpolicy_setid_clear(struct vattr * vap,vnode_t * vp,cred_t * cr)324 secpolicy_setid_clear(struct vattr *vap, vnode_t *vp, cred_t *cr)
325 {
326
327 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
328 return;
329
330 if ((vap->va_mode & (S_ISUID | S_ISGID)) != 0) {
331 if (priv_check_cred(cr, PRIV_VFS_RETAINSUGID)) {
332 vap->va_mask |= AT_MODE;
333 vap->va_mode &= ~(S_ISUID|S_ISGID);
334 }
335 }
336 }
337
338 int
secpolicy_setid_setsticky_clear(vnode_t * vp,struct vattr * vap,const struct vattr * ovap,cred_t * cr)339 secpolicy_setid_setsticky_clear(vnode_t *vp, struct vattr *vap,
340 const struct vattr *ovap, cred_t *cr)
341 {
342 int error;
343
344 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
345 return (0);
346
347 /*
348 * Privileged processes may set the sticky bit on non-directories,
349 * as well as set the setgid bit on a file with a group that the process
350 * is not a member of. Both of these are allowed in jail(8).
351 */
352 if (vp->v_type != VDIR && (vap->va_mode & S_ISTXT)) {
353 if (priv_check_cred(cr, PRIV_VFS_STICKYFILE))
354 return (EFTYPE);
355 }
356 /*
357 * Check for privilege if attempting to set the
358 * group-id bit.
359 */
360 if ((vap->va_mode & S_ISGID) != 0) {
361 error = secpolicy_vnode_setids_setgids(vp, cr, ovap->va_gid);
362 if (error)
363 return (error);
364 }
365 /*
366 * Deny setting setuid if we are not the file owner.
367 */
368 if ((vap->va_mode & S_ISUID) && ovap->va_uid != cr->cr_uid) {
369 error = priv_check_cred(cr, PRIV_VFS_ADMIN);
370 if (error)
371 return (error);
372 }
373 return (0);
374 }
375
376 int
secpolicy_fs_mount(cred_t * cr,vnode_t * mvp,struct mount * vfsp)377 secpolicy_fs_mount(cred_t *cr, vnode_t *mvp, struct mount *vfsp)
378 {
379
380 return (priv_check_cred(cr, PRIV_VFS_MOUNT));
381 }
382
383 int
secpolicy_vnode_owner(vnode_t * vp,cred_t * cr,uid_t owner)384 secpolicy_vnode_owner(vnode_t *vp, cred_t *cr, uid_t owner)
385 {
386
387 if (owner == cr->cr_uid)
388 return (0);
389 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
390 return (0);
391
392 /* XXX: vfs_suser()? */
393 return (priv_check_cred(cr, PRIV_VFS_MOUNT_OWNER));
394 }
395
396 int
secpolicy_vnode_chown(vnode_t * vp,cred_t * cr,uid_t owner)397 secpolicy_vnode_chown(vnode_t *vp, cred_t *cr, uid_t owner)
398 {
399
400 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
401 return (0);
402 return (priv_check_cred(cr, PRIV_VFS_CHOWN));
403 }
404
405 void
secpolicy_fs_mount_clearopts(cred_t * cr,struct mount * vfsp)406 secpolicy_fs_mount_clearopts(cred_t *cr, struct mount *vfsp)
407 {
408
409 if (priv_check_cred(cr, PRIV_VFS_MOUNT_NONUSER) != 0) {
410 MNT_ILOCK(vfsp);
411 vfsp->vfs_flag |= VFS_NOSETUID | MNT_USER;
412 vfs_clearmntopt(vfsp, MNTOPT_SETUID);
413 vfs_setmntopt(vfsp, MNTOPT_NOSETUID, NULL, 0);
414 MNT_IUNLOCK(vfsp);
415 }
416 }
417
418 /*
419 * Check privileges for setting xvattr attributes
420 */
421 int
secpolicy_xvattr(vnode_t * vp,xvattr_t * xvap,uid_t owner,cred_t * cr,vtype_t vtype)422 secpolicy_xvattr(vnode_t *vp, xvattr_t *xvap, uid_t owner, cred_t *cr,
423 vtype_t vtype)
424 {
425
426 if (secpolicy_fs_owner(vp->v_mount, cr) == 0)
427 return (0);
428 return (priv_check_cred(cr, PRIV_VFS_SYSFLAGS));
429 }
430
431 int
secpolicy_smb(cred_t * cr)432 secpolicy_smb(cred_t *cr)
433 {
434
435 return (priv_check_cred(cr, PRIV_NETSMB));
436 }
437