1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21 /*
22 * Copyright 2010 Sun Microsystems, Inc. All rights reserved.
23 * Use is subject to license terms.
24 */
25
26 /* Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T */
27 /* All Rights Reserved */
28
29 /*
30 * Portions of this source code were derived from Berkeley 4.3 BSD
31 * under license from the Regents of the University of California.
32 */
33
34 #include <sys/param.h>
35 #include <sys/isa_defs.h>
36 #include <sys/types.h>
37 #include <sys/sysmacros.h>
38 #include <sys/cred.h>
39 #include <sys/user.h>
40 #include <sys/systm.h>
41 #include <sys/errno.h>
42 #include <sys/fcntl.h>
43 #include <sys/pathname.h>
44 #include <sys/var.h>
45 #include <sys/vfs.h>
46 #include <sys/vnode.h>
47 #include <sys/file.h>
48 #include <sys/mode.h>
49 #include <sys/proc.h>
50 #include <sys/uio.h>
51 #include <sys/poll.h>
52 #include <sys/kmem.h>
53 #include <sys/filio.h>
54 #include <sys/cmn_err.h>
55 #include <sys/policy.h>
56 #include <sys/zone.h>
57
58 #include <sys/debug.h>
59 #include <c2/audit.h>
60 #include <fs/fs_subr.h>
61
62 /*
63 * Change current working directory (".").
64 */
65 static int chdirec(vnode_t *, int ischroot, int do_traverse);
66
67 int
chdir(char * fname)68 chdir(char *fname)
69 {
70 vnode_t *vp;
71 int error;
72 int estale_retry = 0;
73
74 lookup:
75 if (error = lookupname(fname, UIO_USERSPACE, FOLLOW, NULLVPP, &vp)) {
76 if ((error == ESTALE) && fs_need_estale_retry(estale_retry++))
77 goto lookup;
78 return (set_errno(error));
79 }
80
81 error = chdirec(vp, 0, 1);
82 if (error) {
83 if ((error == ESTALE) && fs_need_estale_retry(estale_retry++))
84 goto lookup;
85 return (set_errno(error));
86 }
87 return (0);
88 }
89
90 /*
91 * File-descriptor based version of 'chdir'.
92 */
93 int
fchdir(int fd)94 fchdir(int fd)
95 {
96 vnode_t *vp;
97 file_t *fp;
98 int error;
99
100 if ((fp = getf(fd)) == NULL)
101 return (set_errno(EBADF));
102 vp = fp->f_vnode;
103 VN_HOLD(vp);
104 releasef(fd);
105 error = chdirec(vp, 0, 0);
106 if (error)
107 return (set_errno(error));
108 return (0);
109 }
110
111 /*
112 * Change notion of root ("/") directory.
113 */
114 int
chroot(char * fname)115 chroot(char *fname)
116 {
117 vnode_t *vp;
118 int error;
119 int estale_retry = 0;
120
121 lookup:
122 if (error = lookupname(fname, UIO_USERSPACE, FOLLOW, NULLVPP, &vp)) {
123 if ((error == ESTALE) && fs_need_estale_retry(estale_retry++))
124 goto lookup;
125 return (set_errno(error));
126 }
127
128 error = chdirec(vp, 1, 1);
129 if (error) {
130 if ((error == ESTALE) && fs_need_estale_retry(estale_retry++))
131 goto lookup;
132 return (set_errno(error));
133 }
134 return (0);
135 }
136
137 /*
138 * ++++++++++++++++++++++++
139 * ++ SunOS4.1 Buyback ++
140 * ++++++++++++++++++++++++
141 * Change root directory with a user given fd
142 */
143 int
fchroot(int fd)144 fchroot(int fd)
145 {
146 vnode_t *vp;
147 file_t *fp;
148 int error;
149
150 if ((fp = getf(fd)) == NULL)
151 return (set_errno(EBADF));
152 vp = fp->f_vnode;
153 VN_HOLD(vp);
154 releasef(fd);
155 error = chdirec(vp, 1, 0);
156 if (error)
157 return (set_errno(error));
158 return (0);
159 }
160
161 static int
chdirec(vnode_t * vp,int ischroot,int do_traverse)162 chdirec(vnode_t *vp, int ischroot, int do_traverse)
163 {
164 int error;
165 vnode_t *oldvp;
166 proc_t *pp = curproc;
167 vnode_t **vpp;
168 refstr_t *cwd;
169 int newcwd = 1;
170
171 if (vp->v_type != VDIR) {
172 error = ENOTDIR;
173 goto bad;
174 }
175 if (error = VOP_ACCESS(vp, VEXEC, 0, CRED(), NULL))
176 goto bad;
177
178 /*
179 * The VOP_ACCESS() may have covered 'vp' with a new filesystem,
180 * if 'vp' is an autoFS vnode. Traverse the mountpoint so
181 * that we don't end up with a covered current directory.
182 */
183 if (vn_mountedvfs(vp) != NULL && do_traverse) {
184 if (error = traverse(&vp))
185 goto bad;
186 }
187
188 /*
189 * Special chroot semantics: chroot is allowed if privileged
190 * or if the target is really a loopback mount of the root (or
191 * root of the zone) as determined by comparing dev and inode
192 * numbers
193 */
194 if (ischroot) {
195 struct vattr tattr;
196 struct vattr rattr;
197 vnode_t *zonevp = curproc->p_zone->zone_rootvp;
198
199 tattr.va_mask = AT_FSID|AT_NODEID;
200 if (error = VOP_GETATTR(vp, &tattr, 0, CRED(), NULL))
201 goto bad;
202
203 rattr.va_mask = AT_FSID|AT_NODEID;
204 if (error = VOP_GETATTR(zonevp, &rattr, 0, CRED(), NULL))
205 goto bad;
206
207 if ((tattr.va_fsid != rattr.va_fsid ||
208 tattr.va_nodeid != rattr.va_nodeid) &&
209 (error = secpolicy_chroot(CRED())) != 0)
210 goto bad;
211
212 vpp = &PTOU(pp)->u_rdir;
213 } else {
214 vpp = &PTOU(pp)->u_cdir;
215 }
216
217 /* update abs cwd/root path see c2/audit.c */
218 if (AU_AUDITING())
219 audit_chdirec(vp, vpp);
220
221 mutex_enter(&pp->p_lock);
222 /*
223 * This bit of logic prevents us from overwriting u_cwd if we are
224 * changing to the same directory. We set the cwd to NULL so that we
225 * don't try to do the lookup on the next call to getcwd().
226 */
227 if (!ischroot && *vpp != NULL && vp != NULL && VN_CMP(*vpp, vp))
228 newcwd = 0;
229
230 oldvp = *vpp;
231 *vpp = vp;
232 if ((cwd = PTOU(pp)->u_cwd) != NULL && newcwd)
233 PTOU(pp)->u_cwd = NULL;
234 mutex_exit(&pp->p_lock);
235
236 if (cwd && newcwd)
237 refstr_rele(cwd);
238 if (oldvp)
239 VN_RELE(oldvp);
240 return (0);
241
242 bad:
243 VN_RELE(vp);
244 return (error);
245 }
246