1 /* $NetBSD: vfs_lookup.c,v 1.42 2002/10/22 03:35:10 simonb Exp $ */ 2 3 /* 4 * Copyright (c) 1982, 1986, 1989, 1993 5 * The Regents of the University of California. All rights reserved. 6 * (c) UNIX System Laboratories, Inc. 7 * All or some portions of this file are derived from material licensed 8 * to the University of California by American Telephone and Telegraph 9 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 10 * the permission of UNIX System Laboratories, Inc. 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. All advertising materials mentioning features or use of this software 21 * must display the following acknowledgement: 22 * This product includes software developed by the University of 23 * California, Berkeley and its contributors. 24 * 4. Neither the name of the University nor the names of its contributors 25 * may be used to endorse or promote products derived from this software 26 * without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 38 * SUCH DAMAGE. 39 * 40 * @(#)vfs_lookup.c 8.10 (Berkeley) 5/27/95 41 */ 42 43 #include <sys/cdefs.h> 44 __KERNEL_RCSID(0, "$NetBSD: vfs_lookup.c,v 1.42 2002/10/22 03:35:10 simonb Exp $"); 45 46 #include "opt_ktrace.h" 47 48 #include <sys/param.h> 49 #include <sys/systm.h> 50 #include <sys/syslimits.h> 51 #include <sys/time.h> 52 #include <sys/namei.h> 53 #include <sys/vnode.h> 54 #include <sys/mount.h> 55 #include <sys/errno.h> 56 #include <sys/filedesc.h> 57 #include <sys/hash.h> 58 #include <sys/malloc.h> 59 #include <sys/proc.h> 60 #include <sys/syslog.h> 61 62 #ifdef KTRACE 63 #include <sys/ktrace.h> 64 #endif 65 66 struct pool pnbuf_pool; /* pathname buffer pool */ 67 struct pool_cache pnbuf_cache; /* pathname buffer cache */ 68 69 /* 70 * Convert a pathname into a pointer to a locked inode. 71 * 72 * The FOLLOW flag is set when symbolic links are to be followed 73 * when they occur at the end of the name translation process. 74 * Symbolic links are always followed for all other pathname 75 * components other than the last. 76 * 77 * The segflg defines whether the name is to be copied from user 78 * space or kernel space. 79 * 80 * Overall outline of namei: 81 * 82 * copy in name 83 * get starting directory 84 * while (!done && !error) { 85 * call lookup to search path. 86 * if symbolic link, massage name in buffer and continue 87 * } 88 */ 89 int 90 namei(ndp) 91 struct nameidata *ndp; 92 { 93 struct cwdinfo *cwdi; /* pointer to cwd state */ 94 char *cp; /* pointer into pathname argument */ 95 struct vnode *dp; /* the directory we are searching */ 96 struct iovec aiov; /* uio for reading symbolic links */ 97 struct uio auio; 98 int error, linklen; 99 struct componentname *cnp = &ndp->ni_cnd; 100 101 #ifdef DIAGNOSTIC 102 if (!cnp->cn_cred || !cnp->cn_proc) 103 panic ("namei: bad cred/proc"); 104 if (cnp->cn_nameiop & (~OPMASK)) 105 panic ("namei: nameiop contaminated with flags"); 106 if (cnp->cn_flags & OPMASK) 107 panic ("namei: flags contaminated with nameiops"); 108 #endif 109 cwdi = cnp->cn_proc->p_cwdi; 110 111 /* 112 * Get a buffer for the name to be translated, and copy the 113 * name into the buffer. 114 */ 115 if ((cnp->cn_flags & HASBUF) == 0) 116 cnp->cn_pnbuf = PNBUF_GET(); 117 if (ndp->ni_segflg == UIO_SYSSPACE) 118 error = copystr(ndp->ni_dirp, cnp->cn_pnbuf, 119 MAXPATHLEN, &ndp->ni_pathlen); 120 else 121 error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf, 122 MAXPATHLEN, &ndp->ni_pathlen); 123 124 /* 125 * POSIX.1 requirement: "" is not a valid file name. 126 */ 127 if (!error && ndp->ni_pathlen == 1) 128 error = ENOENT; 129 130 if (error) { 131 PNBUF_PUT(cnp->cn_pnbuf); 132 ndp->ni_vp = NULL; 133 return (error); 134 } 135 ndp->ni_loopcnt = 0; 136 137 #ifdef KTRACE 138 if (KTRPOINT(cnp->cn_proc, KTR_NAMEI)) 139 ktrnamei(cnp->cn_proc, cnp->cn_pnbuf); 140 #endif 141 142 /* 143 * Get starting point for the translation. 144 */ 145 if ((ndp->ni_rootdir = cwdi->cwdi_rdir) == NULL) 146 ndp->ni_rootdir = rootvnode; 147 /* 148 * Check if starting from root directory or current directory. 149 */ 150 if (cnp->cn_pnbuf[0] == '/') { 151 dp = ndp->ni_rootdir; 152 VREF(dp); 153 } else { 154 dp = cwdi->cwdi_cdir; 155 VREF(dp); 156 } 157 for (;;) { 158 cnp->cn_nameptr = cnp->cn_pnbuf; 159 ndp->ni_startdir = dp; 160 if ((error = lookup(ndp)) != 0) { 161 PNBUF_PUT(cnp->cn_pnbuf); 162 return (error); 163 } 164 /* 165 * Check for symbolic link 166 */ 167 if ((cnp->cn_flags & ISSYMLINK) == 0) { 168 if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) 169 PNBUF_PUT(cnp->cn_pnbuf); 170 else 171 cnp->cn_flags |= HASBUF; 172 return (0); 173 } 174 if ((cnp->cn_flags & LOCKPARENT) && (cnp->cn_flags & ISLASTCN)) 175 VOP_UNLOCK(ndp->ni_dvp, 0); 176 if (ndp->ni_loopcnt++ >= MAXSYMLINKS) { 177 error = ELOOP; 178 break; 179 } 180 if (ndp->ni_vp->v_mount->mnt_flag & MNT_SYMPERM) { 181 error = VOP_ACCESS(ndp->ni_vp, VEXEC, cnp->cn_cred, 182 cnp->cn_proc); 183 if (error != 0) 184 break; 185 } 186 if (ndp->ni_pathlen > 1) 187 cp = PNBUF_GET(); 188 else 189 cp = cnp->cn_pnbuf; 190 aiov.iov_base = cp; 191 aiov.iov_len = MAXPATHLEN; 192 auio.uio_iov = &aiov; 193 auio.uio_iovcnt = 1; 194 auio.uio_offset = 0; 195 auio.uio_rw = UIO_READ; 196 auio.uio_segflg = UIO_SYSSPACE; 197 auio.uio_procp = (struct proc *)0; 198 auio.uio_resid = MAXPATHLEN; 199 error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred); 200 if (error) { 201 badlink: 202 if (ndp->ni_pathlen > 1) 203 PNBUF_PUT(cp); 204 break; 205 } 206 linklen = MAXPATHLEN - auio.uio_resid; 207 if (linklen == 0) { 208 error = ENOENT; 209 goto badlink; 210 } 211 if (linklen + ndp->ni_pathlen >= MAXPATHLEN) { 212 error = ENAMETOOLONG; 213 goto badlink; 214 } 215 if (ndp->ni_pathlen > 1) { 216 memcpy(cp + linklen, ndp->ni_next, ndp->ni_pathlen); 217 PNBUF_PUT(cnp->cn_pnbuf); 218 cnp->cn_pnbuf = cp; 219 } else 220 cnp->cn_pnbuf[linklen] = '\0'; 221 ndp->ni_pathlen += linklen; 222 vput(ndp->ni_vp); 223 dp = ndp->ni_dvp; 224 /* 225 * Check if root directory should replace current directory. 226 */ 227 if (cnp->cn_pnbuf[0] == '/') { 228 vrele(dp); 229 dp = ndp->ni_rootdir; 230 VREF(dp); 231 } 232 } 233 PNBUF_PUT(cnp->cn_pnbuf); 234 vrele(ndp->ni_dvp); 235 vput(ndp->ni_vp); 236 ndp->ni_vp = NULL; 237 return (error); 238 } 239 240 /* 241 * Determine the namei hash (for cn_hash) for name. 242 * If *ep != NULL, hash from name to ep-1. 243 * If *ep == NULL, hash from name until the first NUL or '/', and 244 * return the location of this termination character in *ep. 245 * 246 * This function returns an equivalent hash to the MI hash32_strn(). 247 * The latter isn't used because in the *ep == NULL case, determining 248 * the length of the string to the first NUL or `/' and then calling 249 * hash32_strn() involves unnecessary double-handling of the data. 250 */ 251 uint32_t 252 namei_hash(const char *name, const char **ep) 253 { 254 uint32_t hash; 255 256 hash = HASH32_STR_INIT; 257 if (*ep != NULL) { 258 for (; name < *ep; name++) 259 hash = hash * 33 + *(uint8_t *)name; 260 } else { 261 for (; *name != '\0' && *name != '/'; name++) 262 hash = hash * 33 + *(uint8_t *)name; 263 *ep = name; 264 } 265 return (hash + (hash >> 5)); 266 } 267 268 /* 269 * Search a pathname. 270 * This is a very central and rather complicated routine. 271 * 272 * The pathname is pointed to by ni_ptr and is of length ni_pathlen. 273 * The starting directory is taken from ni_startdir. The pathname is 274 * descended until done, or a symbolic link is encountered. The variable 275 * ni_more is clear if the path is completed; it is set to one if a 276 * symbolic link needing interpretation is encountered. 277 * 278 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on 279 * whether the name is to be looked up, created, renamed, or deleted. 280 * When CREATE, RENAME, or DELETE is specified, information usable in 281 * creating, renaming, or deleting a directory entry may be calculated. 282 * If flag has LOCKPARENT or'ed into it, the parent directory is returned 283 * locked. If flag has WANTPARENT or'ed into it, the parent directory is 284 * returned unlocked. Otherwise the parent directory is not returned. If 285 * the target of the pathname exists and LOCKLEAF is or'ed into the flag 286 * the target is returned locked, otherwise it is returned unlocked. 287 * When creating or renaming and LOCKPARENT is specified, the target may not 288 * be ".". When deleting and LOCKPARENT is specified, the target may be ".". 289 * 290 * Overall outline of lookup: 291 * 292 * dirloop: 293 * identify next component of name at ndp->ni_ptr 294 * handle degenerate case where name is null string 295 * if .. and crossing mount points and on mounted filesys, find parent 296 * call VOP_LOOKUP routine for next component name 297 * directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set 298 * component vnode returned in ni_vp (if it exists), locked. 299 * if result vnode is mounted on and crossing mount points, 300 * find mounted on vnode 301 * if more components of name, do next level at dirloop 302 * return the answer in ni_vp, locked if LOCKLEAF set 303 * if LOCKPARENT set, return locked parent in ni_dvp 304 * if WANTPARENT set, return unlocked parent in ni_dvp 305 */ 306 int 307 lookup(ndp) 308 struct nameidata *ndp; 309 { 310 const char *cp; /* pointer into pathname argument */ 311 struct vnode *dp = 0; /* the directory we are searching */ 312 struct vnode *tdp; /* saved dp */ 313 struct mount *mp; /* mount table entry */ 314 int docache; /* == 0 do not cache last component */ 315 int wantparent; /* 1 => wantparent or lockparent flag */ 316 int rdonly; /* lookup read-only flag bit */ 317 int error = 0; 318 int slashes; 319 int dpunlocked = 0; /* dp has already been unlocked */ 320 struct componentname *cnp = &ndp->ni_cnd; 321 322 /* 323 * Setup: break out flag bits into variables. 324 */ 325 wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT); 326 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE; 327 if (cnp->cn_nameiop == DELETE || 328 (wantparent && cnp->cn_nameiop != CREATE)) 329 docache = 0; 330 rdonly = cnp->cn_flags & RDONLY; 331 ndp->ni_dvp = NULL; 332 cnp->cn_flags &= ~ISSYMLINK; 333 dp = ndp->ni_startdir; 334 ndp->ni_startdir = NULLVP; 335 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY); 336 337 /* 338 * If we have a leading string of slashes, remove them, and just make 339 * sure the current node is a directory. 340 */ 341 cp = cnp->cn_nameptr; 342 if (*cp == '/') { 343 do { 344 cp++; 345 } while (*cp == '/'); 346 ndp->ni_pathlen -= cp - cnp->cn_nameptr; 347 cnp->cn_nameptr = cp; 348 349 if (dp->v_type != VDIR) { 350 error = ENOTDIR; 351 goto bad; 352 } 353 354 /* 355 * If we've exhausted the path name, then just return the 356 * current node. If the caller requested the parent node (i.e. 357 * it's a CREATE, DELETE, or RENAME), and we don't have one 358 * (because this is the root directory), then we must fail. 359 */ 360 if (cnp->cn_nameptr[0] == '\0') { 361 if (ndp->ni_dvp == NULL && wantparent) { 362 error = EISDIR; 363 goto bad; 364 } 365 ndp->ni_vp = dp; 366 cnp->cn_flags |= ISLASTCN; 367 goto terminal; 368 } 369 } 370 371 dirloop: 372 /* 373 * Search a new directory. 374 * 375 * The cn_hash value is for use by vfs_cache. 376 * The last component of the filename is left accessible via 377 * cnp->cn_nameptr for callers that need the name. Callers needing 378 * the name set the SAVENAME flag. When done, they assume 379 * responsibility for freeing the pathname buffer. 380 */ 381 cnp->cn_consume = 0; 382 cp = NULL; 383 cnp->cn_hash = namei_hash(cnp->cn_nameptr, &cp); 384 cnp->cn_namelen = cp - cnp->cn_nameptr; 385 if (cnp->cn_namelen > NAME_MAX) { 386 error = ENAMETOOLONG; 387 goto bad; 388 } 389 #ifdef NAMEI_DIAGNOSTIC 390 { char c = *cp; 391 *(char *)cp = '\0'; 392 printf("{%s}: ", cnp->cn_nameptr); 393 *(char *)cp = c; } 394 #endif 395 ndp->ni_pathlen -= cnp->cn_namelen; 396 ndp->ni_next = cp; 397 /* 398 * If this component is followed by a slash, then move the pointer to 399 * the next component forward, and remember that this component must be 400 * a directory. 401 */ 402 if (*cp == '/') { 403 do { 404 cp++; 405 } while (*cp == '/'); 406 slashes = cp - ndp->ni_next; 407 ndp->ni_pathlen -= slashes; 408 ndp->ni_next = cp; 409 cnp->cn_flags |= REQUIREDIR; 410 } else { 411 slashes = 0; 412 cnp->cn_flags &= ~REQUIREDIR; 413 } 414 /* 415 * We do special processing on the last component, whether or not it's 416 * a directory. Cache all intervening lookups, but not the final one. 417 */ 418 if (*cp == '\0') { 419 if (docache) 420 cnp->cn_flags |= MAKEENTRY; 421 else 422 cnp->cn_flags &= ~MAKEENTRY; 423 cnp->cn_flags |= ISLASTCN; 424 } else { 425 cnp->cn_flags |= MAKEENTRY; 426 cnp->cn_flags &= ~ISLASTCN; 427 } 428 if (cnp->cn_namelen == 2 && 429 cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.') 430 cnp->cn_flags |= ISDOTDOT; 431 else 432 cnp->cn_flags &= ~ISDOTDOT; 433 434 /* 435 * Handle "..": two special cases. 436 * 1. If at root directory (e.g. after chroot) 437 * or at absolute root directory 438 * then ignore it so can't get out. 439 * 1a. If we have somehow gotten out of a jail, warn 440 * and also ignore it so we can't get farther out. 441 * 2. If this vnode is the root of a mounted 442 * filesystem, then replace it with the 443 * vnode which was mounted on so we take the 444 * .. in the other file system. 445 */ 446 if (cnp->cn_flags & ISDOTDOT) { 447 for (;;) { 448 if (dp == ndp->ni_rootdir || dp == rootvnode) { 449 ndp->ni_dvp = dp; 450 ndp->ni_vp = dp; 451 VREF(dp); 452 goto nextname; 453 } 454 if (ndp->ni_rootdir != rootvnode) { 455 int retval; 456 VOP_UNLOCK(dp, 0); 457 retval = vn_isunder(dp, ndp->ni_rootdir, 458 cnp->cn_proc); 459 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY); 460 if (!retval) { 461 /* Oops! We got out of jail! */ 462 log(LOG_WARNING, 463 "chrooted pid %d uid %d (%s) " 464 "detected outside of its chroot\n", 465 cnp->cn_proc->p_pid, 466 cnp->cn_proc->p_ucred->cr_uid, 467 cnp->cn_proc->p_comm); 468 /* Put us at the jail root. */ 469 vput(dp); 470 dp = ndp->ni_rootdir; 471 ndp->ni_dvp = dp; 472 ndp->ni_vp = dp; 473 VREF(dp); 474 VREF(dp); 475 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY); 476 goto nextname; 477 } 478 } 479 if ((dp->v_flag & VROOT) == 0 || 480 (cnp->cn_flags & NOCROSSMOUNT)) 481 break; 482 tdp = dp; 483 dp = dp->v_mount->mnt_vnodecovered; 484 vput(tdp); 485 VREF(dp); 486 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY); 487 } 488 } 489 490 /* 491 * We now have a segment name to search for, and a directory to search. 492 */ 493 unionlookup: 494 ndp->ni_dvp = dp; 495 ndp->ni_vp = NULL; 496 cnp->cn_flags &= ~PDIRUNLOCK; 497 if ((error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp)) != 0) { 498 #ifdef DIAGNOSTIC 499 if (ndp->ni_vp != NULL) 500 panic("leaf should be empty"); 501 #endif 502 #ifdef NAMEI_DIAGNOSTIC 503 printf("not found\n"); 504 #endif 505 if ((error == ENOENT) && 506 (dp->v_flag & VROOT) && 507 (dp->v_mount->mnt_flag & MNT_UNION)) { 508 tdp = dp; 509 dp = dp->v_mount->mnt_vnodecovered; 510 if (cnp->cn_flags & PDIRUNLOCK) 511 vrele(tdp); 512 else 513 vput(tdp); 514 VREF(dp); 515 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY); 516 goto unionlookup; 517 } 518 519 if (error != EJUSTRETURN) 520 goto bad; 521 /* 522 * If this was not the last component, or there were trailing 523 * slashes, then the name must exist. 524 */ 525 if (cnp->cn_flags & REQUIREDIR) { 526 error = ENOENT; 527 goto bad; 528 } 529 /* 530 * If creating and at end of pathname, then can consider 531 * allowing file to be created. 532 */ 533 if (rdonly) { 534 error = EROFS; 535 goto bad; 536 } 537 /* 538 * We return with ni_vp NULL to indicate that the entry 539 * doesn't currently exist, leaving a pointer to the 540 * (possibly locked) directory inode in ndp->ni_dvp. 541 */ 542 if (cnp->cn_flags & SAVESTART) { 543 ndp->ni_startdir = ndp->ni_dvp; 544 VREF(ndp->ni_startdir); 545 } 546 return (0); 547 } 548 #ifdef NAMEI_DIAGNOSTIC 549 printf("found\n"); 550 #endif 551 552 /* 553 * Take into account any additional components consumed by the 554 * underlying filesystem. This will include any trailing slashes after 555 * the last component consumed. 556 */ 557 if (cnp->cn_consume > 0) { 558 ndp->ni_pathlen -= cnp->cn_consume - slashes; 559 ndp->ni_next += cnp->cn_consume - slashes; 560 cnp->cn_consume = 0; 561 if (ndp->ni_next[0] == '\0') 562 cnp->cn_flags |= ISLASTCN; 563 } 564 565 dp = ndp->ni_vp; 566 /* 567 * Check to see if the vnode has been mounted on; 568 * if so find the root of the mounted file system. 569 */ 570 while (dp->v_type == VDIR && (mp = dp->v_mountedhere) && 571 (cnp->cn_flags & NOCROSSMOUNT) == 0) { 572 if (vfs_busy(mp, 0, 0)) 573 continue; 574 VOP_UNLOCK(dp, 0); 575 error = VFS_ROOT(mp, &tdp); 576 vfs_unbusy(mp); 577 if (error) { 578 dpunlocked = 1; 579 goto bad2; 580 } 581 vrele(dp); 582 ndp->ni_vp = dp = tdp; 583 } 584 585 /* 586 * Check for symbolic link. Back up over any slashes that we skipped, 587 * as we will need them again. 588 */ 589 if ((dp->v_type == VLNK) && (cnp->cn_flags & (FOLLOW|REQUIREDIR))) { 590 ndp->ni_pathlen += slashes; 591 ndp->ni_next -= slashes; 592 cnp->cn_flags |= ISSYMLINK; 593 return (0); 594 } 595 596 /* 597 * Check for directory, if the component was followed by a series of 598 * slashes. 599 */ 600 if ((dp->v_type != VDIR) && (cnp->cn_flags & REQUIREDIR)) { 601 error = ENOTDIR; 602 goto bad2; 603 } 604 605 nextname: 606 /* 607 * Not a symbolic link. If this was not the last component, then 608 * continue at the next component, else return. 609 */ 610 if (!(cnp->cn_flags & ISLASTCN)) { 611 cnp->cn_nameptr = ndp->ni_next; 612 vrele(ndp->ni_dvp); 613 goto dirloop; 614 } 615 616 terminal: 617 /* 618 * Disallow directory write attempts on read-only file systems. 619 */ 620 if (rdonly && 621 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 622 /* 623 * Disallow directory write attempts on read-only 624 * file systems. 625 */ 626 error = EROFS; 627 goto bad2; 628 } 629 if (ndp->ni_dvp != NULL) { 630 if (cnp->cn_flags & SAVESTART) { 631 ndp->ni_startdir = ndp->ni_dvp; 632 VREF(ndp->ni_startdir); 633 } 634 if (!wantparent) 635 vrele(ndp->ni_dvp); 636 } 637 if ((cnp->cn_flags & LOCKLEAF) == 0) 638 VOP_UNLOCK(dp, 0); 639 return (0); 640 641 bad2: 642 if ((cnp->cn_flags & LOCKPARENT) && (cnp->cn_flags & ISLASTCN) && 643 ((cnp->cn_flags & PDIRUNLOCK) == 0)) 644 VOP_UNLOCK(ndp->ni_dvp, 0); 645 vrele(ndp->ni_dvp); 646 bad: 647 if (dpunlocked) 648 vrele(dp); 649 else 650 vput(dp); 651 ndp->ni_vp = NULL; 652 return (error); 653 } 654 655 /* 656 * Reacquire a path name component. 657 */ 658 int 659 relookup(dvp, vpp, cnp) 660 struct vnode *dvp, **vpp; 661 struct componentname *cnp; 662 { 663 struct vnode *dp = 0; /* the directory we are searching */ 664 int wantparent; /* 1 => wantparent or lockparent flag */ 665 int rdonly; /* lookup read-only flag bit */ 666 int error = 0; 667 #ifdef NAMEI_DIAGNOSTIC 668 int newhash; /* DEBUG: check name hash */ 669 const char *cp; /* DEBUG: check name ptr/len */ 670 #endif 671 672 /* 673 * Setup: break out flag bits into variables. 674 */ 675 wantparent = cnp->cn_flags & (LOCKPARENT|WANTPARENT); 676 rdonly = cnp->cn_flags & RDONLY; 677 cnp->cn_flags &= ~ISSYMLINK; 678 dp = dvp; 679 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY); 680 681 /* dirloop: */ 682 /* 683 * Search a new directory. 684 * 685 * The cn_hash value is for use by vfs_cache. 686 * The last component of the filename is left accessible via 687 * cnp->cn_nameptr for callers that need the name. Callers needing 688 * the name set the SAVENAME flag. When done, they assume 689 * responsibility for freeing the pathname buffer. 690 */ 691 #ifdef NAMEI_DIAGNOSTIC 692 cp = NULL; 693 newhash = namei_hash(cnp->cn_nameptr, &cp); 694 if (newhash != cnp->cn_hash) 695 panic("relookup: bad hash"); 696 if (cnp->cn_namelen != cp - cnp->cn_nameptr) 697 panic ("relookup: bad len"); 698 if (*cp != 0) 699 panic("relookup: not last component"); 700 printf("{%s}: ", cnp->cn_nameptr); 701 #endif 702 703 /* 704 * Check for degenerate name (e.g. / or "") 705 * which is a way of talking about a directory, 706 * e.g. like "/." or ".". 707 */ 708 if (cnp->cn_nameptr[0] == '\0') 709 panic("relookup: null name"); 710 711 if (cnp->cn_flags & ISDOTDOT) 712 panic ("relookup: lookup on dot-dot"); 713 714 /* 715 * We now have a segment name to search for, and a directory to search. 716 */ 717 if ((error = VOP_LOOKUP(dp, vpp, cnp)) != 0) { 718 #ifdef DIAGNOSTIC 719 if (*vpp != NULL) 720 panic("leaf should be empty"); 721 #endif 722 if (error != EJUSTRETURN) 723 goto bad; 724 /* 725 * If creating and at end of pathname, then can consider 726 * allowing file to be created. 727 */ 728 if (rdonly) { 729 error = EROFS; 730 goto bad; 731 } 732 /* ASSERT(dvp == ndp->ni_startdir) */ 733 if (cnp->cn_flags & SAVESTART) 734 VREF(dvp); 735 /* 736 * We return with ni_vp NULL to indicate that the entry 737 * doesn't currently exist, leaving a pointer to the 738 * (possibly locked) directory inode in ndp->ni_dvp. 739 */ 740 return (0); 741 } 742 dp = *vpp; 743 744 #ifdef DIAGNOSTIC 745 /* 746 * Check for symbolic link 747 */ 748 if (dp->v_type == VLNK && (cnp->cn_flags & FOLLOW)) 749 panic ("relookup: symlink found.\n"); 750 #endif 751 752 /* 753 * Check for read-only file systems. 754 */ 755 if (rdonly && 756 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 757 error = EROFS; 758 goto bad2; 759 } 760 /* ASSERT(dvp == ndp->ni_startdir) */ 761 if (cnp->cn_flags & SAVESTART) 762 VREF(dvp); 763 if (!wantparent) 764 vrele(dvp); 765 if ((cnp->cn_flags & LOCKLEAF) == 0) 766 VOP_UNLOCK(dp, 0); 767 return (0); 768 769 bad2: 770 if ((cnp->cn_flags & LOCKPARENT) && (cnp->cn_flags & ISLASTCN)) 771 VOP_UNLOCK(dvp, 0); 772 vrele(dvp); 773 bad: 774 vput(dp); 775 *vpp = NULL; 776 return (error); 777 } 778