1 /* $NetBSD: cd9660_lookup.c,v 1.25 2013/06/23 07:28:36 dholland Exp $ */ 2 3 /*- 4 * Copyright (c) 1989, 1993, 1994 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley 8 * by Pace Willisson (pace@blitz.com). The Rock Ridge Extension 9 * Support code is derived from software contributed to Berkeley 10 * by Atsushi Murai (amurai@spec.co.jp). 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * from: @(#)ufs_lookup.c 7.33 (Berkeley) 5/19/91 37 * 38 * @(#)cd9660_lookup.c 8.5 (Berkeley) 5/27/95 39 */ 40 41 #include <sys/cdefs.h> 42 __KERNEL_RCSID(0, "$NetBSD: cd9660_lookup.c,v 1.25 2013/06/23 07:28:36 dholland Exp $"); 43 44 #include <sys/param.h> 45 #include <sys/namei.h> 46 #include <sys/buf.h> 47 #include <sys/file.h> 48 #include <sys/vnode.h> 49 #include <sys/mount.h> 50 #include <sys/systm.h> 51 #include <sys/kauth.h> 52 53 #include <fs/cd9660/iso.h> 54 #include <fs/cd9660/cd9660_extern.h> 55 #include <fs/cd9660/cd9660_node.h> 56 #include <fs/cd9660/iso_rrip.h> 57 #include <fs/cd9660/cd9660_rrip.h> 58 #include <fs/cd9660/cd9660_mount.h> 59 60 struct nchstats iso_nchstats; 61 62 /* 63 * Convert a component of a pathname into a pointer to a locked inode. 64 * This is a very central and rather complicated routine. 65 * If the file system is not maintained in a strict tree hierarchy, 66 * this can result in a deadlock situation (see comments in code below). 67 * 68 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on 69 * whether the name is to be looked up, created, renamed, or deleted. 70 * When CREATE, RENAME, or DELETE is specified, information usable in 71 * creating, renaming, or deleting a directory entry may be calculated. 72 * If the target of the pathname exists, lookup returns both the target 73 * and its parent directory locked. 74 * When creating or renaming, the target may * not be ".". 75 * When deleting , the target may be "."., but the caller must check 76 * to ensure it does an vrele and vput instead of two vputs. 77 * 78 * Overall outline of ufs_lookup: 79 * 80 * check accessibility of directory 81 * look for name in cache, if found, then if at end of path 82 * and deleting or creating, drop it, else return name 83 * search for name in directory, to found or notfound 84 * notfound: 85 * if creating, return locked directory, leaving info on available slots 86 * else return error 87 * found: 88 * if at end of path and deleting, return information to allow delete 89 * if at end of path and rewriting (RENAME), lock target 90 * inode and return info to allow rewrite 91 * if not at end, add name to cache; if at end and neither creating 92 * nor deleting, add name to cache 93 */ 94 int 95 cd9660_lookup(void *v) 96 { 97 struct vop_lookup_args /* { 98 struct vnode *a_dvp; 99 struct vnode **a_vpp; 100 struct componentname *a_cnp; 101 } */ *ap = v; 102 struct vnode *vdp; /* vnode for directory being searched */ 103 struct iso_node *dp; /* inode for directory being searched */ 104 struct iso_mnt *imp; /* file system that directory is in */ 105 struct buf *bp; /* a buffer of directory entries */ 106 struct iso_directory_record *ep = NULL; 107 /* the current directory entry */ 108 int entryoffsetinblock; /* offset of ep in bp's buffer */ 109 int saveoffset = -1; /* offset of last directory entry in dir */ 110 int numdirpasses; /* strategy for directory search */ 111 doff_t endsearch; /* offset to end directory search */ 112 struct vnode *pdp; /* saved dp during symlink work */ 113 struct vnode *tdp; /* returned by cd9660_vget_internal */ 114 u_long bmask; /* block offset mask */ 115 int error; 116 ino_t ino = 0; 117 int reclen; 118 u_short namelen; 119 char altname[ISO_MAXNAMLEN]; 120 int res; 121 int assoc, len; 122 const char *name; 123 struct vnode **vpp = ap->a_vpp; 124 struct componentname *cnp = ap->a_cnp; 125 kauth_cred_t cred = cnp->cn_cred; 126 int flags; 127 int nameiop = cnp->cn_nameiop; 128 129 flags = cnp->cn_flags; 130 131 bp = NULL; 132 *vpp = NULL; 133 vdp = ap->a_dvp; 134 dp = VTOI(vdp); 135 imp = dp->i_mnt; 136 137 /* 138 * Check accessiblity of directory. 139 */ 140 if ((error = VOP_ACCESS(vdp, VEXEC, cred)) != 0) 141 return (error); 142 143 if ((flags & ISLASTCN) && (vdp->v_mount->mnt_flag & MNT_RDONLY) && 144 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 145 return (EROFS); 146 147 /* 148 * We now have a segment name to search for, and a directory to search. 149 * 150 * Before tediously performing a linear scan of the directory, 151 * check the name cache to see if the directory/name pair 152 * we are looking for is known already. 153 */ 154 if (cache_lookup(vdp, cnp->cn_nameptr, cnp->cn_namelen, 155 cnp->cn_nameiop, cnp->cn_flags, NULL, vpp)) { 156 return *vpp == NULLVP ? ENOENT : 0; 157 } 158 159 len = cnp->cn_namelen; 160 name = cnp->cn_nameptr; 161 /* 162 * A leading `=' means, we are looking for an associated file 163 */ 164 assoc = (imp->iso_ftype != ISO_FTYPE_RRIP && *name == ASSOCCHAR); 165 if (assoc) { 166 len--; 167 name++; 168 } 169 170 /* 171 * If there is cached information on a previous search of 172 * this directory, pick up where we last left off. 173 * We cache only lookups as these are the most common 174 * and have the greatest payoff. Caching CREATE has little 175 * benefit as it usually must search the entire directory 176 * to determine that the entry does not exist. Caching the 177 * location of the last DELETE or RENAME has not reduced 178 * profiling time and hence has been removed in the interest 179 * of simplicity. 180 */ 181 bmask = imp->im_bmask; 182 if (nameiop != LOOKUP || dp->i_diroff == 0 || 183 dp->i_diroff > dp->i_size) { 184 entryoffsetinblock = 0; 185 dp->i_offset = 0; 186 numdirpasses = 1; 187 } else { 188 dp->i_offset = dp->i_diroff; 189 if ((entryoffsetinblock = dp->i_offset & bmask) && 190 (error = cd9660_blkatoff(vdp, (off_t)dp->i_offset, NULL, 191 &bp))) 192 return (error); 193 numdirpasses = 2; 194 iso_nchstats.ncs_2passes++; 195 } 196 endsearch = dp->i_size; 197 198 searchloop: 199 while (dp->i_offset < endsearch) { 200 /* 201 * If offset is on a block boundary, 202 * read the next directory block. 203 * Release previous if it exists. 204 */ 205 if ((dp->i_offset & bmask) == 0) { 206 if (bp != NULL) 207 brelse(bp, 0); 208 error = cd9660_blkatoff(vdp, (off_t)dp->i_offset, 209 NULL, &bp); 210 if (error) 211 return (error); 212 entryoffsetinblock = 0; 213 } 214 /* 215 * Get pointer to next entry. 216 */ 217 KASSERT(bp != NULL); 218 ep = (struct iso_directory_record *) 219 ((char *)bp->b_data + entryoffsetinblock); 220 221 reclen = isonum_711(ep->length); 222 if (reclen == 0) { 223 /* skip to next block, if any */ 224 dp->i_offset = 225 (dp->i_offset & ~bmask) + imp->logical_block_size; 226 continue; 227 } 228 229 if (reclen < ISO_DIRECTORY_RECORD_SIZE) 230 /* illegal entry, stop */ 231 break; 232 233 if (entryoffsetinblock + reclen > imp->logical_block_size) 234 /* entries are not allowed to cross boundaries */ 235 break; 236 237 namelen = isonum_711(ep->name_len); 238 239 if (reclen < ISO_DIRECTORY_RECORD_SIZE + namelen) 240 /* illegal entry, stop */ 241 break; 242 243 /* 244 * Check for a name match. 245 */ 246 switch (imp->iso_ftype) { 247 default: 248 if ((!(isonum_711(ep->flags)&4)) == !assoc) { 249 if ((len == 1 250 && *name == '.') 251 || (flags & ISDOTDOT)) { 252 if (namelen == 1 253 && ep->name[0] == ((flags & ISDOTDOT) ? 1 : 0)) { 254 /* 255 * Save directory entry's inode number and 256 * release directory buffer. 257 */ 258 dp->i_ino = isodirino(ep, imp); 259 goto found; 260 } 261 if (namelen != 1 262 || ep->name[0] != 0) 263 goto notfound; 264 } else if (!(res = isofncmp(name,len, 265 ep->name,namelen, 266 imp->im_joliet_level))) { 267 if (isonum_711(ep->flags)&2) 268 ino = isodirino(ep, imp); 269 else 270 ino = dbtob(bp->b_blkno) 271 + entryoffsetinblock; 272 saveoffset = dp->i_offset; 273 } else if (ino) 274 goto foundino; 275 #ifdef NOSORTBUG /* On some CDs directory entries are not sorted correctly */ 276 else if (res < 0) 277 goto notfound; 278 else if (res > 0 && numdirpasses == 2) 279 numdirpasses++; 280 #endif 281 } 282 break; 283 case ISO_FTYPE_RRIP: 284 if (isonum_711(ep->flags)&2) 285 ino = isodirino(ep, imp); 286 else 287 ino = dbtob(bp->b_blkno) + entryoffsetinblock; 288 dp->i_ino = ino; 289 cd9660_rrip_getname(ep,altname,&namelen,&dp->i_ino,imp); 290 if (namelen == cnp->cn_namelen) { 291 if (imp->im_flags & ISOFSMNT_RRCASEINS) { 292 if (strncasecmp(name, altname, namelen) == 0) 293 goto found; 294 } else { 295 if (memcmp(name, altname, namelen) == 0) 296 goto found; 297 } 298 } 299 ino = 0; 300 break; 301 } 302 dp->i_offset += reclen; 303 entryoffsetinblock += reclen; 304 } 305 if (ino) { 306 foundino: 307 dp->i_ino = ino; 308 if (saveoffset != dp->i_offset) { 309 if (cd9660_lblkno(imp, dp->i_offset) != 310 cd9660_lblkno(imp, saveoffset)) { 311 if (bp != NULL) 312 brelse(bp, 0); 313 if ((error = cd9660_blkatoff(vdp, 314 (off_t)saveoffset, NULL, &bp)) != 0) 315 return (error); 316 } 317 entryoffsetinblock = saveoffset & bmask; 318 ep = (struct iso_directory_record *) 319 ((char *)bp->b_data + entryoffsetinblock); 320 dp->i_offset = saveoffset; 321 } 322 goto found; 323 } 324 notfound: 325 /* 326 * If we started in the middle of the directory and failed 327 * to find our target, we must check the beginning as well. 328 */ 329 if (numdirpasses == 2) { 330 numdirpasses--; 331 dp->i_offset = 0; 332 endsearch = dp->i_diroff; 333 goto searchloop; 334 } 335 if (bp != NULL) 336 brelse(bp, 0); 337 338 /* 339 * Insert name into cache (as non-existent) if appropriate. 340 */ 341 cache_enter(vdp, *vpp, cnp->cn_nameptr, cnp->cn_namelen, cnp->cn_flags); 342 return (nameiop == CREATE || nameiop == RENAME) ? EROFS : ENOENT; 343 344 found: 345 if (numdirpasses == 2) 346 iso_nchstats.ncs_pass2++; 347 348 /* 349 * Found component in pathname. 350 * If the final component of path name, save information 351 * in the cache as to where the entry was found. 352 */ 353 if ((flags & ISLASTCN) && nameiop == LOOKUP) 354 dp->i_diroff = dp->i_offset; 355 356 /* 357 * Step through the translation in the name. We do not `iput' the 358 * directory because we may need it again if a symbolic link 359 * is relative to the current directory. Instead we save it 360 * unlocked as "pdp". We must get the target inode before unlocking 361 * the directory to insure that the inode will not be removed 362 * before we get it. We prevent deadlock by always fetching 363 * inodes from the root, moving down the directory tree. Thus 364 * when following backward pointers ".." we must unlock the 365 * parent directory before getting the requested directory. 366 * There is a potential race condition here if both the current 367 * and parent directories are removed before the `iget' for the 368 * inode associated with ".." returns. We hope that this occurs 369 * infrequently since we cannot avoid this race condition without 370 * implementing a sophisticated deadlock detection algorithm. 371 * Note also that this simple deadlock detection scheme will not 372 * work if the file system has any hard links other than ".." 373 * that point backwards in the directory structure. 374 */ 375 pdp = vdp; 376 377 /* 378 * If ino is different from dp->i_ino, 379 * it's a relocated directory. 380 */ 381 brelse(bp, 0); 382 if (flags & ISDOTDOT) { 383 VOP_UNLOCK(pdp); /* race to get the inode */ 384 error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, &tdp, 385 dp->i_ino != ino, ep); 386 vn_lock(pdp, LK_EXCLUSIVE | LK_RETRY); 387 if (error) 388 return error; 389 *vpp = tdp; 390 } else if (dp->i_number == dp->i_ino) { 391 vref(vdp); /* we want ourself, ie "." */ 392 *vpp = vdp; 393 } else { 394 error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, &tdp, 395 dp->i_ino != ino, ep); 396 if (error) 397 return (error); 398 *vpp = tdp; 399 } 400 401 /* 402 * Insert name into cache if appropriate. 403 */ 404 cache_enter(vdp, *vpp, cnp->cn_nameptr, cnp->cn_namelen, cnp->cn_flags); 405 return 0; 406 } 407 408 /* 409 * Return buffer with the contents of block "offset" from the beginning of 410 * directory "ip". If "res" is non-zero, fill it in with a pointer to the 411 * remaining space in the directory. 412 */ 413 int 414 cd9660_blkatoff(struct vnode *vp, off_t offset, char **res, struct buf **bpp) 415 { 416 struct iso_node *ip; 417 struct iso_mnt *imp; 418 struct buf *bp; 419 daddr_t lbn; 420 int bsize, error; 421 422 ip = VTOI(vp); 423 imp = ip->i_mnt; 424 lbn = cd9660_lblkno(imp, offset); 425 bsize = cd9660_blksize(imp, ip, lbn); 426 427 if ((error = bread(vp, lbn, bsize, NOCRED, 0, &bp)) != 0) { 428 *bpp = NULL; 429 return (error); 430 } 431 if (res) 432 *res = (char *)bp->b_data + cd9660_blkoff(imp, offset); 433 *bpp = bp; 434 return (0); 435 } 436