chdir.c revision 949:807ec422f5ba 
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, Version 1.0 only
6 * (the "License").  You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22/*
23 * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
24 * Use is subject to license terms.
25 */
26
27/*	Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T	*/
28/*	  All Rights Reserved  	*/
29
30/*
31 * Portions of this source code were derived from Berkeley 4.3 BSD
32 * under license from the Regents of the University of California.
33 */
34
35#pragma ident	"%Z%%M%	%I%	%E% SMI"
36
37#include <sys/param.h>
38#include <sys/isa_defs.h>
39#include <sys/types.h>
40#include <sys/sysmacros.h>
41#include <sys/cred.h>
42#include <sys/user.h>
43#include <sys/systm.h>
44#include <sys/errno.h>
45#include <sys/fcntl.h>
46#include <sys/pathname.h>
47#include <sys/var.h>
48#include <sys/vfs.h>
49#include <sys/vnode.h>
50#include <sys/file.h>
51#include <sys/mode.h>
52#include <sys/proc.h>
53#include <sys/uio.h>
54#include <sys/poll.h>
55#include <sys/kmem.h>
56#include <sys/filio.h>
57#include <sys/cmn_err.h>
58#include <sys/policy.h>
59#include <sys/zone.h>
60
61#include <sys/debug.h>
62#include <c2/audit.h>
63
64/*
65 * Change current working directory (".").
66 */
67static int	chdirec(vnode_t *, int ischroot, int do_traverse);
68
69int
70chdir(char *fname)
71{
72	vnode_t *vp;
73	int error;
74
75lookup:
76	if (error = lookupname(fname, UIO_USERSPACE, FOLLOW, NULLVPP, &vp)) {
77		if (error == ESTALE)
78			goto lookup;
79		return (set_errno(error));
80	}
81
82	error = chdirec(vp, 0, 1);
83	if (error) {
84		if (error == ESTALE)
85			goto lookup;
86		return (set_errno(error));
87	}
88	return (0);
89}
90
91/*
92 * File-descriptor based version of 'chdir'.
93 */
94int
95fchdir(int fd)
96{
97	vnode_t *vp;
98	file_t *fp;
99	int error;
100
101	if ((fp = getf(fd)) == NULL)
102		return (set_errno(EBADF));
103	vp = fp->f_vnode;
104	VN_HOLD(vp);
105	releasef(fd);
106	error = chdirec(vp, 0, 0);
107	if (error)
108		return (set_errno(error));
109	return (0);
110}
111
112/*
113 * Change notion of root ("/") directory.
114 */
115int
116chroot(char *fname)
117{
118	vnode_t *vp;
119	int error;
120
121lookup:
122	if (error = lookupname(fname, UIO_USERSPACE, FOLLOW, NULLVPP, &vp)) {
123		if (error == ESTALE)
124			goto lookup;
125		return (set_errno(error));
126	}
127
128	error = chdirec(vp, 1, 1);
129	if (error) {
130		if (error == ESTALE)
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 */
143int
144fchroot(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
161static int
162chdirec(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()))
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()))
201			goto bad;
202
203		rattr.va_mask = AT_FSID|AT_NODEID;
204		if (error = VOP_GETATTR(zonevp, &rattr, 0, CRED()))
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#ifdef C2_AUDIT
218	if (audit_active)	/* update abs cwd/root path see c2audit.c */
219		audit_chdirec(vp, vpp);
220#endif
221
222	mutex_enter(&pp->p_lock);
223	/*
224	 * This bit of logic prevents us from overwriting u_cwd if we are
225	 * changing to the same directory.  We set the cwd to NULL so that we
226	 * don't try to do the lookup on the next call to getcwd().
227	 */
228	if (!ischroot && *vpp != NULL && vp != NULL && VN_CMP(*vpp, vp))
229		newcwd = 0;
230
231	oldvp = *vpp;
232	*vpp = vp;
233	if ((cwd = PTOU(pp)->u_cwd) != NULL && newcwd)
234		PTOU(pp)->u_cwd = NULL;
235	mutex_exit(&pp->p_lock);
236
237	if (cwd && newcwd)
238		refstr_rele(cwd);
239	if (oldvp)
240		VN_RELE(oldvp);
241	return (0);
242
243bad:
244	VN_RELE(vp);
245	return (error);
246}
247