opensolaris_policy.c revision 197860 
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: head/sys/cddl/compat/opensolaris/kern/opensolaris_policy.c 197860 2009-10-08 16:03:19Z pjd $");
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
40int
41secpolicy_nfs(struct ucred *cred)
42{
43
44	return (priv_check_cred(cred, PRIV_NFS_DAEMON, 0));
45}
46
47int
48secpolicy_zfs(struct ucred *cred)
49{
50
51	return (priv_check_cred(cred, PRIV_VFS_MOUNT, 0));
52}
53
54int
55secpolicy_sys_config(struct ucred *cred, int checkonly __unused)
56{
57
58	return (priv_check_cred(cred, PRIV_ZFS_POOL_CONFIG, 0));
59}
60
61int
62secpolicy_zinject(struct ucred *cred)
63{
64
65	return (priv_check_cred(cred, PRIV_ZFS_INJECT, 0));
66}
67
68int
69secpolicy_fs_unmount(struct ucred *cred, struct mount *vfsp __unused)
70{
71
72	return (priv_check_cred(cred, PRIV_VFS_UNMOUNT, 0));
73}
74
75int
76secpolicy_fs_owner(struct mount *mp, struct ucred *cred)
77{
78
79	if (zfs_super_owner) {
80		if (cred->cr_uid == mp->mnt_cred->cr_uid &&
81		    cred->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 */
91extern int hardlink_check_uid;
92int
93secpolicy_basic_link(struct vnode *vp, struct ucred *cred)
94{
95
96	if (!hardlink_check_uid)
97		return (0);
98	if (secpolicy_fs_owner(vp->v_mount, cred) == 0)
99		return (0);
100	return (priv_check_cred(cred, PRIV_VFS_LINK, 0));
101}
102
103int
104secpolicy_vnode_stky_modify(struct ucred *cred)
105{
106
107	return (EPERM);
108}
109
110int
111secpolicy_vnode_remove(struct vnode *vp, struct ucred *cred)
112{
113
114	if (secpolicy_fs_owner(vp->v_mount, cred) == 0)
115		return (0);
116	return (priv_check_cred(cred, PRIV_VFS_ADMIN, 0));
117}
118
119int
120secpolicy_vnode_access(struct ucred *cred, struct vnode *vp, uint64_t owner,
121    accmode_t accmode)
122{
123
124	if (secpolicy_fs_owner(vp->v_mount, cred) == 0)
125		return (0);
126
127	if ((accmode & VREAD) && priv_check_cred(cred, PRIV_VFS_READ, 0) != 0)
128		return (EACCES);
129	if ((accmode & VWRITE) &&
130	    priv_check_cred(cred, PRIV_VFS_WRITE, 0) != 0) {
131		return (EACCES);
132	}
133	if (accmode & VEXEC) {
134		if (vp->v_type == VDIR) {
135			if (priv_check_cred(cred, PRIV_VFS_LOOKUP, 0) != 0) {
136				return (EACCES);
137			}
138		} else {
139			if (priv_check_cred(cred, PRIV_VFS_EXEC, 0) != 0) {
140				return (EACCES);
141			}
142		}
143	}
144	return (0);
145}
146
147int
148secpolicy_vnode_setdac(struct vnode *vp, struct ucred *cred, uid_t owner)
149{
150
151	if (owner == cred->cr_uid)
152		return (0);
153	if (secpolicy_fs_owner(vp->v_mount, cred) == 0)
154		return (0);
155	return (priv_check_cred(cred, PRIV_VFS_ADMIN, 0));
156}
157
158int
159secpolicy_vnode_setattr(struct ucred *cred, struct vnode *vp, struct vattr *vap,
160    const struct vattr *ovap, int flags,
161    int unlocked_access(void *, int, struct ucred *), void *node)
162{
163	int mask = vap->va_mask;
164	int error;
165
166	if (mask & AT_SIZE) {
167		if (vp->v_type == VDIR)
168			return (EISDIR);
169		error = unlocked_access(node, VWRITE, cred);
170		if (error)
171			return (error);
172	}
173	if (mask & AT_MODE) {
174		/*
175		 * If not the owner of the file then check privilege
176		 * for two things: the privilege to set the mode at all
177		 * and, if we're setting setuid, we also need permissions
178		 * to add the set-uid bit, if we're not the owner.
179		 * In the specific case of creating a set-uid root
180		 * file, we need even more permissions.
181		 */
182		error = secpolicy_vnode_setdac(vp, cred, ovap->va_uid);
183		if (error)
184			return (error);
185		error = secpolicy_setid_setsticky_clear(vp, vap, ovap, cred);
186		if (error)
187			return (error);
188	} else {
189		vap->va_mode = ovap->va_mode;
190	}
191	if (mask & (AT_UID | AT_GID)) {
192		error = secpolicy_vnode_setdac(vp, cred, ovap->va_uid);
193		if (error)
194			return (error);
195
196		/*
197		 * To change the owner of a file, or change the group of a file to a
198		 * group of which we are not a member, the caller must have
199		 * privilege.
200		 */
201		if (((mask & AT_UID) && vap->va_uid != ovap->va_uid) ||
202		    ((mask & AT_GID) && vap->va_gid != ovap->va_gid &&
203		     !groupmember(vap->va_gid, cred))) {
204			if (secpolicy_fs_owner(vp->v_mount, cred) != 0) {
205				error = priv_check_cred(cred, PRIV_VFS_CHOWN, 0);
206				if (error)
207					return (error);
208			}
209		}
210
211		if (((mask & AT_UID) && vap->va_uid != ovap->va_uid) ||
212		    ((mask & AT_GID) && vap->va_gid != ovap->va_gid)) {
213			secpolicy_setid_clear(vap, vp, cred);
214		}
215	}
216	if (mask & (AT_ATIME | AT_MTIME)) {
217		/*
218		 * From utimes(2):
219		 * If times is NULL, ... The caller must be the owner of
220		 * the file, have permission to write the file, or be the
221		 * super-user.
222		 * If times is non-NULL, ... The caller must be the owner of
223		 * the file or be the super-user.
224		 */
225		error = secpolicy_vnode_setdac(vp, cred, ovap->va_uid);
226		if (error && (vap->va_vaflags & VA_UTIMES_NULL))
227			error = unlocked_access(node, VWRITE, cred);
228		if (error)
229			return (error);
230	}
231	return (0);
232}
233
234int
235secpolicy_vnode_create_gid(struct ucred *cred)
236{
237
238	return (EPERM);
239}
240
241int
242secpolicy_vnode_setids_setgids(struct vnode *vp, struct ucred *cred, gid_t gid)
243{
244
245	if (groupmember(gid, cred))
246		return (0);
247	if (secpolicy_fs_owner(vp->v_mount, cred) == 0)
248		return (0);
249	return (priv_check_cred(cred, PRIV_VFS_SETGID, 0));
250}
251
252int
253secpolicy_vnode_setid_retain(struct vnode *vp, struct ucred *cred,
254    boolean_t issuidroot __unused)
255{
256
257	if (secpolicy_fs_owner(vp->v_mount, cred) == 0)
258		return (0);
259	return (priv_check_cred(cred, PRIV_VFS_RETAINSUGID, 0));
260}
261
262void
263secpolicy_setid_clear(struct vattr *vap, struct vnode *vp, struct ucred *cred)
264{
265
266	if (secpolicy_fs_owner(vp->v_mount, cred) == 0)
267		return;
268
269	if ((vap->va_mode & (S_ISUID | S_ISGID)) != 0) {
270		if (priv_check_cred(cred, PRIV_VFS_RETAINSUGID, 0)) {
271			vap->va_mask |= AT_MODE;
272			vap->va_mode &= ~(S_ISUID|S_ISGID);
273		}
274	}
275}
276
277int
278secpolicy_setid_setsticky_clear(struct vnode *vp, struct vattr *vap,
279    const struct vattr *ovap, struct ucred *cred)
280{
281        int error;
282
283	if (secpolicy_fs_owner(vp->v_mount, cred) == 0)
284		return (0);
285
286	/*
287	 * Privileged processes may set the sticky bit on non-directories,
288	 * as well as set the setgid bit on a file with a group that the process
289	 * is not a member of. Both of these are allowed in jail(8).
290	 */
291	if (vp->v_type != VDIR && (vap->va_mode & S_ISTXT)) {
292		if (priv_check_cred(cred, PRIV_VFS_STICKYFILE, 0))
293			return (EFTYPE);
294	}
295	/*
296	 * Check for privilege if attempting to set the
297	 * group-id bit.
298	 */
299	if ((vap->va_mode & S_ISGID) != 0) {
300		error = secpolicy_vnode_setids_setgids(vp, cred, ovap->va_gid);
301		if (error)
302			return (error);
303	}
304	/*
305	 * Deny setting setuid if we are not the file owner.
306	 */
307	if ((vap->va_mode & S_ISUID) && ovap->va_uid != cred->cr_uid) {
308		error = priv_check_cred(cred, PRIV_VFS_ADMIN, 0);
309		if (error)
310			return (error);
311	}
312	return (0);
313}
314
315int
316secpolicy_fs_mount(cred_t *cr, vnode_t *mvp, struct mount *vfsp)
317{
318
319	return (priv_check_cred(cr, PRIV_VFS_MOUNT, 0));
320}
321
322int
323secpolicy_vnode_owner(struct vnode *vp, cred_t *cred, uid_t owner)
324{
325
326	if (owner == cred->cr_uid)
327		return (0);
328	if (secpolicy_fs_owner(vp->v_mount, cred) == 0)
329		return (0);
330
331	/* XXX: vfs_suser()? */
332	return (priv_check_cred(cred, PRIV_VFS_MOUNT_OWNER, 0));
333}
334
335int
336secpolicy_vnode_chown(struct vnode *vp, cred_t *cred, boolean_t check_self)
337{
338
339	if (secpolicy_fs_owner(vp->v_mount, cred) == 0)
340		return (0);
341	return (priv_check_cred(cred, PRIV_VFS_CHOWN, 0));
342}
343
344void
345secpolicy_fs_mount_clearopts(cred_t *cr, struct mount *vfsp)
346{
347
348	if (priv_check_cred(cr, PRIV_VFS_MOUNT_NONUSER, 0) != 0) {
349		MNT_ILOCK(vfsp);
350		vfsp->vfs_flag |= VFS_NOSETUID | MNT_USER;
351		vfs_clearmntopt(vfsp, MNTOPT_SETUID);
352		vfs_setmntopt(vfsp, MNTOPT_NOSETUID, NULL, 0);
353		MNT_IUNLOCK(vfsp);
354	}
355}
356
357/*
358 * Check privileges for setting xvattr attributes
359 */
360int
361secpolicy_xvattr(xvattr_t *xvap, uid_t owner, cred_t *cr, vtype_t vtype)
362{
363
364	return (priv_check_cred(cr, PRIV_VFS_SYSFLAGS, 0));
365}
366