chdir.c revision 11861:a63258283f8f
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 */ 65static int chdirec(vnode_t *, int ischroot, int do_traverse); 66 67int 68chdir(char *fname) 69{ 70 vnode_t *vp; 71 int error; 72 int estale_retry = 0; 73 74lookup: 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 */ 93int 94fchdir(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 */ 114int 115chroot(char *fname) 116{ 117 vnode_t *vp; 118 int error; 119 int estale_retry = 0; 120 121lookup: 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 */ 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(), 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 242bad: 243 VN_RELE(vp); 244 return (error); 245} 246