Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/vfs_lookup.c
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1 /*- 2 * Copyright (c) 1982, 1986, 1989, 1993 3 * The Regents of the University of California. All rights reserved. 4 * (c) UNIX System Laboratories, Inc. 5 * All or some portions of this file are derived from material licensed 6 * to the University of California by American Telephone and Telegraph 7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 8 * the permission of UNIX System Laboratories, Inc. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 4. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * @(#)vfs_lookup.c 8.4 (Berkeley) 2/16/94 35 */ 36 37 #include <sys/cdefs.h> 38 __FBSDID("$FreeBSD$"); 39 40 #include "opt_capsicum.h" 41 #include "opt_kdtrace.h" 42 #include "opt_ktrace.h" 43 44 #include <sys/param.h> 45 #include <sys/systm.h> 46 #include <sys/kernel.h> 47 #include <sys/capability.h> 48 #include <sys/fcntl.h> 49 #include <sys/jail.h> 50 #include <sys/lock.h> 51 #include <sys/mutex.h> 52 #include <sys/namei.h> 53 #include <sys/vnode.h> 54 #include <sys/mount.h> 55 #include <sys/filedesc.h> 56 #include <sys/proc.h> 57 #include <sys/sdt.h> 58 #include <sys/syscallsubr.h> 59 #include <sys/sysctl.h> 60 #ifdef KTRACE 61 #include <sys/ktrace.h> 62 #endif 63 64 #include <security/audit/audit.h> 65 #include <security/mac/mac_framework.h> 66 67 #include <vm/uma.h> 68 69 #define NAMEI_DIAGNOSTIC 1 70 #undef NAMEI_DIAGNOSTIC 71 72 SDT_PROVIDER_DECLARE(vfs); 73 SDT_PROBE_DEFINE3(vfs, namei, lookup, entry, "struct vnode *", "char *", 74 "unsigned long"); 75 SDT_PROBE_DEFINE2(vfs, namei, lookup, return, "int", "struct vnode *"); 76 77 /* 78 * Allocation zone for namei 79 */ 80 uma_zone_t namei_zone; 81 /* 82 * Placeholder vnode for mp traversal 83 */ 84 static struct vnode *vp_crossmp; 85 86 static void 87 nameiinit(void *dummy __unused) 88 { 89 90 namei_zone = uma_zcreate("NAMEI", MAXPATHLEN, NULL, NULL, NULL, NULL, 91 UMA_ALIGN_PTR, 0); 92 getnewvnode("crossmp", NULL, &dead_vnodeops, &vp_crossmp); 93 vn_lock(vp_crossmp, LK_EXCLUSIVE); 94 VN_LOCK_ASHARE(vp_crossmp); 95 VOP_UNLOCK(vp_crossmp, 0); 96 } 97 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nameiinit, NULL); 98 99 static int lookup_shared = 1; 100 SYSCTL_INT(_vfs, OID_AUTO, lookup_shared, CTLFLAG_RW, &lookup_shared, 0, 101 "Enables/Disables shared locks for path name translation"); 102 TUNABLE_INT("vfs.lookup_shared", &lookup_shared); 103 104 /* 105 * Convert a pathname into a pointer to a locked vnode. 106 * 107 * The FOLLOW flag is set when symbolic links are to be followed 108 * when they occur at the end of the name translation process. 109 * Symbolic links are always followed for all other pathname 110 * components other than the last. 111 * 112 * The segflg defines whether the name is to be copied from user 113 * space or kernel space. 114 * 115 * Overall outline of namei: 116 * 117 * copy in name 118 * get starting directory 119 * while (!done && !error) { 120 * call lookup to search path. 121 * if symbolic link, massage name in buffer and continue 122 * } 123 */ 124 static void 125 namei_cleanup_cnp(struct componentname *cnp) 126 { 127 uma_zfree(namei_zone, cnp->cn_pnbuf); 128 #ifdef DIAGNOSTIC 129 cnp->cn_pnbuf = NULL; 130 cnp->cn_nameptr = NULL; 131 #endif 132 } 133 134 int 135 namei(struct nameidata *ndp) 136 { 137 struct filedesc *fdp; /* pointer to file descriptor state */ 138 char *cp; /* pointer into pathname argument */ 139 struct vnode *dp; /* the directory we are searching */ 140 struct iovec aiov; /* uio for reading symbolic links */ 141 struct uio auio; 142 int error, linklen; 143 struct componentname *cnp = &ndp->ni_cnd; 144 struct thread *td = cnp->cn_thread; 145 struct proc *p = td->td_proc; 146 int vfslocked; 147 148 KASSERT((cnp->cn_flags & MPSAFE) != 0 || mtx_owned(&Giant) != 0, 149 ("NOT MPSAFE and Giant not held")); 150 ndp->ni_cnd.cn_cred = ndp->ni_cnd.cn_thread->td_ucred; 151 KASSERT(cnp->cn_cred && p, ("namei: bad cred/proc")); 152 KASSERT((cnp->cn_nameiop & (~OPMASK)) == 0, 153 ("namei: nameiop contaminated with flags")); 154 KASSERT((cnp->cn_flags & OPMASK) == 0, 155 ("namei: flags contaminated with nameiops")); 156 if (!lookup_shared) 157 cnp->cn_flags &= ~LOCKSHARED; 158 fdp = p->p_fd; 159 160 /* We will set this ourselves if we need it. */ 161 cnp->cn_flags &= ~TRAILINGSLASH; 162 163 /* 164 * Get a buffer for the name to be translated, and copy the 165 * name into the buffer. 166 */ 167 if ((cnp->cn_flags & HASBUF) == 0) 168 cnp->cn_pnbuf = uma_zalloc(namei_zone, M_WAITOK); 169 if (ndp->ni_segflg == UIO_SYSSPACE) 170 error = copystr(ndp->ni_dirp, cnp->cn_pnbuf, 171 MAXPATHLEN, (size_t *)&ndp->ni_pathlen); 172 else 173 error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf, 174 MAXPATHLEN, (size_t *)&ndp->ni_pathlen); 175 176 /* 177 * Don't allow empty pathnames. 178 */ 179 if (!error && *cnp->cn_pnbuf == '\0') 180 error = ENOENT; 181 182 #ifdef CAPABILITY_MODE 183 /* 184 * In capability mode, lookups must be "strictly relative" (i.e. 185 * not an absolute path, and not containing '..' components) to 186 * a real file descriptor, not the pseudo-descriptor AT_FDCWD. 187 */ 188 if (error == 0 && IN_CAPABILITY_MODE(td)) { 189 ndp->ni_strictrelative = 1; 190 if (ndp->ni_dirfd == AT_FDCWD) 191 error = ECAPMODE; 192 } 193 #endif 194 if (error) { 195 namei_cleanup_cnp(cnp); 196 ndp->ni_vp = NULL; 197 return (error); 198 } 199 ndp->ni_loopcnt = 0; 200 #ifdef KTRACE 201 if (KTRPOINT(td, KTR_NAMEI)) { 202 KASSERT(cnp->cn_thread == curthread, 203 ("namei not using curthread")); 204 ktrnamei(cnp->cn_pnbuf); 205 } 206 #endif 207 /* 208 * Get starting point for the translation. 209 */ 210 FILEDESC_SLOCK(fdp); 211 ndp->ni_rootdir = fdp->fd_rdir; 212 ndp->ni_topdir = fdp->fd_jdir; 213 214 /* 215 * If we are auditing the kernel pathname, save the user pathname. 216 */ 217 if (cnp->cn_flags & AUDITVNODE1) 218 AUDIT_ARG_UPATH1(td, ndp->ni_dirfd, cnp->cn_pnbuf); 219 if (cnp->cn_flags & AUDITVNODE2) 220 AUDIT_ARG_UPATH2(td, ndp->ni_dirfd, cnp->cn_pnbuf); 221 222 dp = NULL; 223 if (cnp->cn_pnbuf[0] != '/') { 224 if (ndp->ni_startdir != NULL) { 225 dp = ndp->ni_startdir; 226 error = 0; 227 } else if (ndp->ni_dirfd != AT_FDCWD) { 228 if (cnp->cn_flags & AUDITVNODE1) 229 AUDIT_ARG_ATFD1(ndp->ni_dirfd); 230 if (cnp->cn_flags & AUDITVNODE2) 231 AUDIT_ARG_ATFD2(ndp->ni_dirfd); 232 error = fgetvp_rights(td, ndp->ni_dirfd, 233 ndp->ni_rightsneeded | CAP_LOOKUP, 234 &(ndp->ni_baserights), &dp); 235 #ifdef CAPABILITIES 236 /* 237 * Lookups relative to a capability must also be 238 * strictly relative. 239 * 240 * Note that a capability with rights CAP_MASK_VALID 241 * is treated exactly like a regular file descriptor. 242 */ 243 if (ndp->ni_baserights != CAP_MASK_VALID) 244 ndp->ni_strictrelative = 1; 245 #endif 246 } 247 if (error != 0 || dp != NULL) { 248 FILEDESC_SUNLOCK(fdp); 249 if (error == 0 && dp->v_type != VDIR) { 250 vfslocked = VFS_LOCK_GIANT(dp->v_mount); 251 vrele(dp); 252 VFS_UNLOCK_GIANT(vfslocked); 253 error = ENOTDIR; 254 } 255 } 256 if (error) { 257 namei_cleanup_cnp(cnp); 258 return (error); 259 } 260 } 261 if (dp == NULL) { 262 dp = fdp->fd_cdir; 263 VREF(dp); 264 FILEDESC_SUNLOCK(fdp); 265 if (ndp->ni_startdir != NULL) { 266 vfslocked = VFS_LOCK_GIANT(ndp->ni_startdir->v_mount); 267 vrele(ndp->ni_startdir); 268 VFS_UNLOCK_GIANT(vfslocked); 269 } 270 } 271 SDT_PROBE3(vfs, namei, lookup, entry, dp, cnp->cn_pnbuf, 272 cnp->cn_flags); 273 vfslocked = VFS_LOCK_GIANT(dp->v_mount); 274 for (;;) { 275 /* 276 * Check if root directory should replace current directory. 277 * Done at start of translation and after symbolic link. 278 */ 279 cnp->cn_nameptr = cnp->cn_pnbuf; 280 if (*(cnp->cn_nameptr) == '/') { 281 vrele(dp); 282 VFS_UNLOCK_GIANT(vfslocked); 283 if (ndp->ni_strictrelative != 0) { 284 namei_cleanup_cnp(cnp); 285 return (ENOTCAPABLE); 286 } 287 while (*(cnp->cn_nameptr) == '/') { 288 cnp->cn_nameptr++; 289 ndp->ni_pathlen--; 290 } 291 dp = ndp->ni_rootdir; 292 vfslocked = VFS_LOCK_GIANT(dp->v_mount); 293 VREF(dp); 294 } 295 if (vfslocked) 296 ndp->ni_cnd.cn_flags |= GIANTHELD; 297 ndp->ni_startdir = dp; 298 error = lookup(ndp); 299 if (error) { 300 namei_cleanup_cnp(cnp); 301 SDT_PROBE2(vfs, namei, lookup, return, error, NULL); 302 return (error); 303 } 304 vfslocked = (ndp->ni_cnd.cn_flags & GIANTHELD) != 0; 305 ndp->ni_cnd.cn_flags &= ~GIANTHELD; 306 /* 307 * If not a symbolic link, we're done. 308 */ 309 if ((cnp->cn_flags & ISSYMLINK) == 0) { 310 if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) { 311 namei_cleanup_cnp(cnp); 312 } else 313 cnp->cn_flags |= HASBUF; 314 315 if ((cnp->cn_flags & MPSAFE) == 0) { 316 VFS_UNLOCK_GIANT(vfslocked); 317 } else if (vfslocked) 318 ndp->ni_cnd.cn_flags |= GIANTHELD; 319 SDT_PROBE2(vfs, namei, lookup, return, 0, ndp->ni_vp); 320 return (0); 321 } 322 if (ndp->ni_loopcnt++ >= MAXSYMLINKS) { 323 error = ELOOP; 324 break; 325 } 326 #ifdef MAC 327 if ((cnp->cn_flags & NOMACCHECK) == 0) { 328 error = mac_vnode_check_readlink(td->td_ucred, 329 ndp->ni_vp); 330 if (error) 331 break; 332 } 333 #endif 334 if (ndp->ni_pathlen > 1) 335 cp = uma_zalloc(namei_zone, M_WAITOK); 336 else 337 cp = cnp->cn_pnbuf; 338 aiov.iov_base = cp; 339 aiov.iov_len = MAXPATHLEN; 340 auio.uio_iov = &aiov; 341 auio.uio_iovcnt = 1; 342 auio.uio_offset = 0; 343 auio.uio_rw = UIO_READ; 344 auio.uio_segflg = UIO_SYSSPACE; 345 auio.uio_td = td; 346 auio.uio_resid = MAXPATHLEN; 347 error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred); 348 if (error) { 349 if (ndp->ni_pathlen > 1) 350 uma_zfree(namei_zone, cp); 351 break; 352 } 353 linklen = MAXPATHLEN - auio.uio_resid; 354 if (linklen == 0) { 355 if (ndp->ni_pathlen > 1) 356 uma_zfree(namei_zone, cp); 357 error = ENOENT; 358 break; 359 } 360 if (linklen + ndp->ni_pathlen >= MAXPATHLEN) { 361 if (ndp->ni_pathlen > 1) 362 uma_zfree(namei_zone, cp); 363 error = ENAMETOOLONG; 364 break; 365 } 366 if (ndp->ni_pathlen > 1) { 367 bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen); 368 uma_zfree(namei_zone, cnp->cn_pnbuf); 369 cnp->cn_pnbuf = cp; 370 } else 371 cnp->cn_pnbuf[linklen] = '\0'; 372 ndp->ni_pathlen += linklen; 373 vput(ndp->ni_vp); 374 dp = ndp->ni_dvp; 375 } 376 namei_cleanup_cnp(cnp); 377 vput(ndp->ni_vp); 378 ndp->ni_vp = NULL; 379 vrele(ndp->ni_dvp); 380 VFS_UNLOCK_GIANT(vfslocked); 381 SDT_PROBE2(vfs, namei, lookup, return, error, NULL); 382 return (error); 383 } 384 385 static int 386 compute_cn_lkflags(struct mount *mp, int lkflags, int cnflags) 387 { 388 389 if (mp == NULL || ((lkflags & LK_SHARED) && 390 (!(mp->mnt_kern_flag & MNTK_LOOKUP_SHARED) || 391 ((cnflags & ISDOTDOT) && 392 (mp->mnt_kern_flag & MNTK_LOOKUP_EXCL_DOTDOT))))) { 393 lkflags &= ~LK_SHARED; 394 lkflags |= LK_EXCLUSIVE; 395 } 396 return (lkflags); 397 } 398 399 static __inline int 400 needs_exclusive_leaf(struct mount *mp, int flags) 401 { 402 403 /* 404 * Intermediate nodes can use shared locks, we only need to 405 * force an exclusive lock for leaf nodes. 406 */ 407 if ((flags & (ISLASTCN | LOCKLEAF)) != (ISLASTCN | LOCKLEAF)) 408 return (0); 409 410 /* Always use exclusive locks if LOCKSHARED isn't set. */ 411 if (!(flags & LOCKSHARED)) 412 return (1); 413 414 /* 415 * For lookups during open(), if the mount point supports 416 * extended shared operations, then use a shared lock for the 417 * leaf node, otherwise use an exclusive lock. 418 */ 419 if (flags & ISOPEN) { 420 if (mp != NULL && 421 (mp->mnt_kern_flag & MNTK_EXTENDED_SHARED)) 422 return (0); 423 else 424 return (1); 425 } 426 427 /* 428 * Lookup requests outside of open() that specify LOCKSHARED 429 * only need a shared lock on the leaf vnode. 430 */ 431 return (0); 432 } 433 434 /* 435 * Search a pathname. 436 * This is a very central and rather complicated routine. 437 * 438 * The pathname is pointed to by ni_ptr and is of length ni_pathlen. 439 * The starting directory is taken from ni_startdir. The pathname is 440 * descended until done, or a symbolic link is encountered. The variable 441 * ni_more is clear if the path is completed; it is set to one if a 442 * symbolic link needing interpretation is encountered. 443 * 444 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on 445 * whether the name is to be looked up, created, renamed, or deleted. 446 * When CREATE, RENAME, or DELETE is specified, information usable in 447 * creating, renaming, or deleting a directory entry may be calculated. 448 * If flag has LOCKPARENT or'ed into it, the parent directory is returned 449 * locked. If flag has WANTPARENT or'ed into it, the parent directory is 450 * returned unlocked. Otherwise the parent directory is not returned. If 451 * the target of the pathname exists and LOCKLEAF is or'ed into the flag 452 * the target is returned locked, otherwise it is returned unlocked. 453 * When creating or renaming and LOCKPARENT is specified, the target may not 454 * be ".". When deleting and LOCKPARENT is specified, the target may be ".". 455 * 456 * Overall outline of lookup: 457 * 458 * dirloop: 459 * identify next component of name at ndp->ni_ptr 460 * handle degenerate case where name is null string 461 * if .. and crossing mount points and on mounted filesys, find parent 462 * call VOP_LOOKUP routine for next component name 463 * directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set 464 * component vnode returned in ni_vp (if it exists), locked. 465 * if result vnode is mounted on and crossing mount points, 466 * find mounted on vnode 467 * if more components of name, do next level at dirloop 468 * return the answer in ni_vp, locked if LOCKLEAF set 469 * if LOCKPARENT set, return locked parent in ni_dvp 470 * if WANTPARENT set, return unlocked parent in ni_dvp 471 */ 472 int 473 lookup(struct nameidata *ndp) 474 { 475 char *cp; /* pointer into pathname argument */ 476 struct vnode *dp = 0; /* the directory we are searching */ 477 struct vnode *tdp; /* saved dp */ 478 struct mount *mp; /* mount table entry */ 479 struct prison *pr; 480 int docache; /* == 0 do not cache last component */ 481 int wantparent; /* 1 => wantparent or lockparent flag */ 482 int rdonly; /* lookup read-only flag bit */ 483 int error = 0; 484 int dpunlocked = 0; /* dp has already been unlocked */ 485 struct componentname *cnp = &ndp->ni_cnd; 486 int vfslocked; /* VFS Giant state for child */ 487 int dvfslocked; /* VFS Giant state for parent */ 488 int tvfslocked; 489 int lkflags_save; 490 int ni_dvp_unlocked; 491 492 /* 493 * Setup: break out flag bits into variables. 494 */ 495 dvfslocked = (ndp->ni_cnd.cn_flags & GIANTHELD) != 0; 496 vfslocked = 0; 497 ni_dvp_unlocked = 0; 498 ndp->ni_cnd.cn_flags &= ~GIANTHELD; 499 wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT); 500 KASSERT(cnp->cn_nameiop == LOOKUP || wantparent, 501 ("CREATE, DELETE, RENAME require LOCKPARENT or WANTPARENT.")); 502 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE; 503 if (cnp->cn_nameiop == DELETE || 504 (wantparent && cnp->cn_nameiop != CREATE && 505 cnp->cn_nameiop != LOOKUP)) 506 docache = 0; 507 rdonly = cnp->cn_flags & RDONLY; 508 cnp->cn_flags &= ~ISSYMLINK; 509 ndp->ni_dvp = NULL; 510 /* 511 * We use shared locks until we hit the parent of the last cn then 512 * we adjust based on the requesting flags. 513 */ 514 if (lookup_shared) 515 cnp->cn_lkflags = LK_SHARED; 516 else 517 cnp->cn_lkflags = LK_EXCLUSIVE; 518 dp = ndp->ni_startdir; 519 ndp->ni_startdir = NULLVP; 520 vn_lock(dp, 521 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | LK_RETRY, 522 cnp->cn_flags)); 523 524 dirloop: 525 /* 526 * Search a new directory. 527 * 528 * The last component of the filename is left accessible via 529 * cnp->cn_nameptr for callers that need the name. Callers needing 530 * the name set the SAVENAME flag. When done, they assume 531 * responsibility for freeing the pathname buffer. 532 */ 533 cnp->cn_consume = 0; 534 for (cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++) 535 continue; 536 cnp->cn_namelen = cp - cnp->cn_nameptr; 537 if (cnp->cn_namelen > NAME_MAX) { 538 error = ENAMETOOLONG; 539 goto bad; 540 } 541 #ifdef NAMEI_DIAGNOSTIC 542 { char c = *cp; 543 *cp = '\0'; 544 printf("{%s}: ", cnp->cn_nameptr); 545 *cp = c; } 546 #endif 547 ndp->ni_pathlen -= cnp->cn_namelen; 548 ndp->ni_next = cp; 549 550 /* 551 * Replace multiple slashes by a single slash and trailing slashes 552 * by a null. This must be done before VOP_LOOKUP() because some 553 * fs's don't know about trailing slashes. Remember if there were 554 * trailing slashes to handle symlinks, existing non-directories 555 * and non-existing files that won't be directories specially later. 556 */ 557 while (*cp == '/' && (cp[1] == '/' || cp[1] == '\0')) { 558 cp++; 559 ndp->ni_pathlen--; 560 if (*cp == '\0') { 561 *ndp->ni_next = '\0'; 562 cnp->cn_flags |= TRAILINGSLASH; 563 } 564 } 565 ndp->ni_next = cp; 566 567 cnp->cn_flags |= MAKEENTRY; 568 if (*cp == '\0' && docache == 0) 569 cnp->cn_flags &= ~MAKEENTRY; 570 if (cnp->cn_namelen == 2 && 571 cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.') 572 cnp->cn_flags |= ISDOTDOT; 573 else 574 cnp->cn_flags &= ~ISDOTDOT; 575 if (*ndp->ni_next == 0) 576 cnp->cn_flags |= ISLASTCN; 577 else 578 cnp->cn_flags &= ~ISLASTCN; 579 580 if ((cnp->cn_flags & ISLASTCN) != 0 && 581 cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.' && 582 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 583 error = EINVAL; 584 goto bad; 585 } 586 587 /* 588 * Check for degenerate name (e.g. / or "") 589 * which is a way of talking about a directory, 590 * e.g. like "/." or ".". 591 */ 592 if (cnp->cn_nameptr[0] == '\0') { 593 if (dp->v_type != VDIR) { 594 error = ENOTDIR; 595 goto bad; 596 } 597 if (cnp->cn_nameiop != LOOKUP) { 598 error = EISDIR; 599 goto bad; 600 } 601 if (wantparent) { 602 ndp->ni_dvp = dp; 603 VREF(dp); 604 } 605 ndp->ni_vp = dp; 606 607 if (cnp->cn_flags & AUDITVNODE1) 608 AUDIT_ARG_VNODE1(dp); 609 else if (cnp->cn_flags & AUDITVNODE2) 610 AUDIT_ARG_VNODE2(dp); 611 612 if (!(cnp->cn_flags & (LOCKPARENT | LOCKLEAF))) 613 VOP_UNLOCK(dp, 0); 614 /* XXX This should probably move to the top of function. */ 615 if (cnp->cn_flags & SAVESTART) 616 panic("lookup: SAVESTART"); 617 goto success; 618 } 619 620 /* 621 * Handle "..": five special cases. 622 * 0. If doing a capability lookup, return ENOTCAPABLE (this is a 623 * fairly conservative design choice, but it's the only one that we 624 * are satisfied guarantees the property we're looking for). 625 * 1. Return an error if this is the last component of 626 * the name and the operation is DELETE or RENAME. 627 * 2. If at root directory (e.g. after chroot) 628 * or at absolute root directory 629 * then ignore it so can't get out. 630 * 3. If this vnode is the root of a mounted 631 * filesystem, then replace it with the 632 * vnode which was mounted on so we take the 633 * .. in the other filesystem. 634 * 4. If the vnode is the top directory of 635 * the jail or chroot, don't let them out. 636 */ 637 if (cnp->cn_flags & ISDOTDOT) { 638 if (ndp->ni_strictrelative != 0) { 639 error = ENOTCAPABLE; 640 goto bad; 641 } 642 if ((cnp->cn_flags & ISLASTCN) != 0 && 643 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 644 error = EINVAL; 645 goto bad; 646 } 647 for (;;) { 648 for (pr = cnp->cn_cred->cr_prison; pr != NULL; 649 pr = pr->pr_parent) 650 if (dp == pr->pr_root) 651 break; 652 if (dp == ndp->ni_rootdir || 653 dp == ndp->ni_topdir || 654 dp == rootvnode || 655 pr != NULL || 656 ((dp->v_vflag & VV_ROOT) != 0 && 657 (cnp->cn_flags & NOCROSSMOUNT) != 0)) { 658 ndp->ni_dvp = dp; 659 ndp->ni_vp = dp; 660 vfslocked = VFS_LOCK_GIANT(dp->v_mount); 661 VREF(dp); 662 goto nextname; 663 } 664 if ((dp->v_vflag & VV_ROOT) == 0) 665 break; 666 if (dp->v_iflag & VI_DOOMED) { /* forced unmount */ 667 error = ENOENT; 668 goto bad; 669 } 670 tdp = dp; 671 dp = dp->v_mount->mnt_vnodecovered; 672 tvfslocked = dvfslocked; 673 dvfslocked = VFS_LOCK_GIANT(dp->v_mount); 674 VREF(dp); 675 vput(tdp); 676 VFS_UNLOCK_GIANT(tvfslocked); 677 vn_lock(dp, 678 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | 679 LK_RETRY, ISDOTDOT)); 680 } 681 } 682 683 /* 684 * We now have a segment name to search for, and a directory to search. 685 */ 686 unionlookup: 687 #ifdef MAC 688 if ((cnp->cn_flags & NOMACCHECK) == 0) { 689 error = mac_vnode_check_lookup(cnp->cn_thread->td_ucred, dp, 690 cnp); 691 if (error) 692 goto bad; 693 } 694 #endif 695 ndp->ni_dvp = dp; 696 ndp->ni_vp = NULL; 697 ASSERT_VOP_LOCKED(dp, "lookup"); 698 VNASSERT(vfslocked == 0, dp, ("lookup: vfslocked %d", vfslocked)); 699 /* 700 * If we have a shared lock we may need to upgrade the lock for the 701 * last operation. 702 */ 703 if (dp != vp_crossmp && 704 VOP_ISLOCKED(dp) == LK_SHARED && 705 (cnp->cn_flags & ISLASTCN) && (cnp->cn_flags & LOCKPARENT)) 706 vn_lock(dp, LK_UPGRADE|LK_RETRY); 707 if ((dp->v_iflag & VI_DOOMED) != 0) { 708 error = ENOENT; 709 goto bad; 710 } 711 /* 712 * If we're looking up the last component and we need an exclusive 713 * lock, adjust our lkflags. 714 */ 715 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags)) 716 cnp->cn_lkflags = LK_EXCLUSIVE; 717 #ifdef NAMEI_DIAGNOSTIC 718 vprint("lookup in", dp); 719 #endif 720 lkflags_save = cnp->cn_lkflags; 721 cnp->cn_lkflags = compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags, 722 cnp->cn_flags); 723 if ((error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp)) != 0) { 724 cnp->cn_lkflags = lkflags_save; 725 KASSERT(ndp->ni_vp == NULL, ("leaf should be empty")); 726 #ifdef NAMEI_DIAGNOSTIC 727 printf("not found\n"); 728 #endif 729 if ((error == ENOENT) && 730 (dp->v_vflag & VV_ROOT) && (dp->v_mount != NULL) && 731 (dp->v_mount->mnt_flag & MNT_UNION)) { 732 tdp = dp; 733 dp = dp->v_mount->mnt_vnodecovered; 734 tvfslocked = dvfslocked; 735 dvfslocked = VFS_LOCK_GIANT(dp->v_mount); 736 VREF(dp); 737 vput(tdp); 738 VFS_UNLOCK_GIANT(tvfslocked); 739 vn_lock(dp, 740 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | 741 LK_RETRY, cnp->cn_flags)); 742 goto unionlookup; 743 } 744 745 if (error != EJUSTRETURN) 746 goto bad; 747 /* 748 * At this point, we know we're at the end of the 749 * pathname. If creating / renaming, we can consider 750 * allowing the file or directory to be created / renamed, 751 * provided we're not on a read-only filesystem. 752 */ 753 if (rdonly) { 754 error = EROFS; 755 goto bad; 756 } 757 /* trailing slash only allowed for directories */ 758 if ((cnp->cn_flags & TRAILINGSLASH) && 759 !(cnp->cn_flags & WILLBEDIR)) { 760 error = ENOENT; 761 goto bad; 762 } 763 if ((cnp->cn_flags & LOCKPARENT) == 0) 764 VOP_UNLOCK(dp, 0); 765 /* 766 * We return with ni_vp NULL to indicate that the entry 767 * doesn't currently exist, leaving a pointer to the 768 * (possibly locked) directory vnode in ndp->ni_dvp. 769 */ 770 if (cnp->cn_flags & SAVESTART) { 771 ndp->ni_startdir = ndp->ni_dvp; 772 VREF(ndp->ni_startdir); 773 } 774 goto success; 775 } else 776 cnp->cn_lkflags = lkflags_save; 777 #ifdef NAMEI_DIAGNOSTIC 778 printf("found\n"); 779 #endif 780 /* 781 * Take into account any additional components consumed by 782 * the underlying filesystem. 783 */ 784 if (cnp->cn_consume > 0) { 785 cnp->cn_nameptr += cnp->cn_consume; 786 ndp->ni_next += cnp->cn_consume; 787 ndp->ni_pathlen -= cnp->cn_consume; 788 cnp->cn_consume = 0; 789 } 790 791 dp = ndp->ni_vp; 792 vfslocked = VFS_LOCK_GIANT(dp->v_mount); 793 794 /* 795 * Check to see if the vnode has been mounted on; 796 * if so find the root of the mounted filesystem. 797 */ 798 while (dp->v_type == VDIR && (mp = dp->v_mountedhere) && 799 (cnp->cn_flags & NOCROSSMOUNT) == 0) { 800 if (vfs_busy(mp, 0)) 801 continue; 802 vput(dp); 803 VFS_UNLOCK_GIANT(vfslocked); 804 vfslocked = VFS_LOCK_GIANT(mp); 805 if (dp != ndp->ni_dvp) 806 vput(ndp->ni_dvp); 807 else 808 vrele(ndp->ni_dvp); 809 VFS_UNLOCK_GIANT(dvfslocked); 810 dvfslocked = 0; 811 vref(vp_crossmp); 812 ndp->ni_dvp = vp_crossmp; 813 error = VFS_ROOT(mp, compute_cn_lkflags(mp, cnp->cn_lkflags, 814 cnp->cn_flags), &tdp); 815 vfs_unbusy(mp); 816 if (vn_lock(vp_crossmp, LK_SHARED | LK_NOWAIT)) 817 panic("vp_crossmp exclusively locked or reclaimed"); 818 if (error) { 819 dpunlocked = 1; 820 goto bad2; 821 } 822 ndp->ni_vp = dp = tdp; 823 } 824 825 /* 826 * Check for symbolic link 827 */ 828 if ((dp->v_type == VLNK) && 829 ((cnp->cn_flags & FOLLOW) || (cnp->cn_flags & TRAILINGSLASH) || 830 *ndp->ni_next == '/')) { 831 cnp->cn_flags |= ISSYMLINK; 832 if (dp->v_iflag & VI_DOOMED) { 833 /* 834 * We can't know whether the directory was mounted with 835 * NOSYMFOLLOW, so we can't follow safely. 836 */ 837 error = ENOENT; 838 goto bad2; 839 } 840 if (dp->v_mount->mnt_flag & MNT_NOSYMFOLLOW) { 841 error = EACCES; 842 goto bad2; 843 } 844 /* 845 * Symlink code always expects an unlocked dvp. 846 */ 847 if (ndp->ni_dvp != ndp->ni_vp) { 848 VOP_UNLOCK(ndp->ni_dvp, 0); 849 ni_dvp_unlocked = 1; 850 } 851 goto success; 852 } 853 854 nextname: 855 /* 856 * Not a symbolic link that we will follow. Continue with the 857 * next component if there is any; otherwise, we're done. 858 */ 859 KASSERT((cnp->cn_flags & ISLASTCN) || *ndp->ni_next == '/', 860 ("lookup: invalid path state.")); 861 if (*ndp->ni_next == '/') { 862 cnp->cn_nameptr = ndp->ni_next; 863 while (*cnp->cn_nameptr == '/') { 864 cnp->cn_nameptr++; 865 ndp->ni_pathlen--; 866 } 867 if (ndp->ni_dvp != dp) 868 vput(ndp->ni_dvp); 869 else 870 vrele(ndp->ni_dvp); 871 VFS_UNLOCK_GIANT(dvfslocked); 872 dvfslocked = vfslocked; /* dp becomes dvp in dirloop */ 873 vfslocked = 0; 874 goto dirloop; 875 } 876 /* 877 * If we're processing a path with a trailing slash, 878 * check that the end result is a directory. 879 */ 880 if ((cnp->cn_flags & TRAILINGSLASH) && dp->v_type != VDIR) { 881 error = ENOTDIR; 882 goto bad2; 883 } 884 /* 885 * Disallow directory write attempts on read-only filesystems. 886 */ 887 if (rdonly && 888 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 889 error = EROFS; 890 goto bad2; 891 } 892 if (cnp->cn_flags & SAVESTART) { 893 ndp->ni_startdir = ndp->ni_dvp; 894 VREF(ndp->ni_startdir); 895 } 896 if (!wantparent) { 897 ni_dvp_unlocked = 2; 898 if (ndp->ni_dvp != dp) 899 vput(ndp->ni_dvp); 900 else 901 vrele(ndp->ni_dvp); 902 VFS_UNLOCK_GIANT(dvfslocked); 903 dvfslocked = 0; 904 } else if ((cnp->cn_flags & LOCKPARENT) == 0 && ndp->ni_dvp != dp) { 905 VOP_UNLOCK(ndp->ni_dvp, 0); 906 ni_dvp_unlocked = 1; 907 } 908 909 if (cnp->cn_flags & AUDITVNODE1) 910 AUDIT_ARG_VNODE1(dp); 911 else if (cnp->cn_flags & AUDITVNODE2) 912 AUDIT_ARG_VNODE2(dp); 913 914 if ((cnp->cn_flags & LOCKLEAF) == 0) 915 VOP_UNLOCK(dp, 0); 916 success: 917 /* 918 * Because of lookup_shared we may have the vnode shared locked, but 919 * the caller may want it to be exclusively locked. 920 */ 921 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags) && 922 VOP_ISLOCKED(dp) != LK_EXCLUSIVE) { 923 vn_lock(dp, LK_UPGRADE | LK_RETRY); 924 if (dp->v_iflag & VI_DOOMED) { 925 error = ENOENT; 926 goto bad2; 927 } 928 } 929 if (vfslocked && dvfslocked) 930 VFS_UNLOCK_GIANT(dvfslocked); /* Only need one */ 931 if (vfslocked || dvfslocked) 932 ndp->ni_cnd.cn_flags |= GIANTHELD; 933 return (0); 934 935 bad2: 936 if (ni_dvp_unlocked != 2) { 937 if (dp != ndp->ni_dvp && !ni_dvp_unlocked) 938 vput(ndp->ni_dvp); 939 else 940 vrele(ndp->ni_dvp); 941 } 942 bad: 943 if (!dpunlocked) 944 vput(dp); 945 VFS_UNLOCK_GIANT(vfslocked); 946 VFS_UNLOCK_GIANT(dvfslocked); 947 ndp->ni_cnd.cn_flags &= ~GIANTHELD; 948 ndp->ni_vp = NULL; 949 return (error); 950 } 951 952 /* 953 * relookup - lookup a path name component 954 * Used by lookup to re-acquire things. 955 */ 956 int 957 relookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp) 958 { 959 struct vnode *dp = 0; /* the directory we are searching */ 960 int wantparent; /* 1 => wantparent or lockparent flag */ 961 int rdonly; /* lookup read-only flag bit */ 962 int error = 0; 963 964 KASSERT(cnp->cn_flags & ISLASTCN, 965 ("relookup: Not given last component.")); 966 /* 967 * Setup: break out flag bits into variables. 968 */ 969 wantparent = cnp->cn_flags & (LOCKPARENT|WANTPARENT); 970 KASSERT(wantparent, ("relookup: parent not wanted.")); 971 rdonly = cnp->cn_flags & RDONLY; 972 cnp->cn_flags &= ~ISSYMLINK; 973 dp = dvp; 974 cnp->cn_lkflags = LK_EXCLUSIVE; 975 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY); 976 977 /* 978 * Search a new directory. 979 * 980 * The last component of the filename is left accessible via 981 * cnp->cn_nameptr for callers that need the name. Callers needing 982 * the name set the SAVENAME flag. When done, they assume 983 * responsibility for freeing the pathname buffer. 984 */ 985 #ifdef NAMEI_DIAGNOSTIC 986 printf("{%s}: ", cnp->cn_nameptr); 987 #endif 988 989 /* 990 * Check for "" which represents the root directory after slash 991 * removal. 992 */ 993 if (cnp->cn_nameptr[0] == '\0') { 994 /* 995 * Support only LOOKUP for "/" because lookup() 996 * can't succeed for CREATE, DELETE and RENAME. 997 */ 998 KASSERT(cnp->cn_nameiop == LOOKUP, ("nameiop must be LOOKUP")); 999 KASSERT(dp->v_type == VDIR, ("dp is not a directory")); 1000 1001 if (!(cnp->cn_flags & LOCKLEAF)) 1002 VOP_UNLOCK(dp, 0); 1003 *vpp = dp; 1004 /* XXX This should probably move to the top of function. */ 1005 if (cnp->cn_flags & SAVESTART) 1006 panic("lookup: SAVESTART"); 1007 return (0); 1008 } 1009 1010 if (cnp->cn_flags & ISDOTDOT) 1011 panic ("relookup: lookup on dot-dot"); 1012 1013 /* 1014 * We now have a segment name to search for, and a directory to search. 1015 */ 1016 #ifdef NAMEI_DIAGNOSTIC 1017 vprint("search in:", dp); 1018 #endif 1019 if ((error = VOP_LOOKUP(dp, vpp, cnp)) != 0) { 1020 KASSERT(*vpp == NULL, ("leaf should be empty")); 1021 if (error != EJUSTRETURN) 1022 goto bad; 1023 /* 1024 * If creating and at end of pathname, then can consider 1025 * allowing file to be created. 1026 */ 1027 if (rdonly) { 1028 error = EROFS; 1029 goto bad; 1030 } 1031 /* ASSERT(dvp == ndp->ni_startdir) */ 1032 if (cnp->cn_flags & SAVESTART) 1033 VREF(dvp); 1034 if ((cnp->cn_flags & LOCKPARENT) == 0) 1035 VOP_UNLOCK(dp, 0); 1036 /* 1037 * We return with ni_vp NULL to indicate that the entry 1038 * doesn't currently exist, leaving a pointer to the 1039 * (possibly locked) directory vnode in ndp->ni_dvp. 1040 */ 1041 return (0); 1042 } 1043 1044 dp = *vpp; 1045 1046 /* 1047 * Disallow directory write attempts on read-only filesystems. 1048 */ 1049 if (rdonly && 1050 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 1051 if (dvp == dp) 1052 vrele(dvp); 1053 else 1054 vput(dvp); 1055 error = EROFS; 1056 goto bad; 1057 } 1058 /* 1059 * Set the parent lock/ref state to the requested state. 1060 */ 1061 if ((cnp->cn_flags & LOCKPARENT) == 0 && dvp != dp) { 1062 if (wantparent) 1063 VOP_UNLOCK(dvp, 0); 1064 else 1065 vput(dvp); 1066 } else if (!wantparent) 1067 vrele(dvp); 1068 /* 1069 * Check for symbolic link 1070 */ 1071 KASSERT(dp->v_type != VLNK || !(cnp->cn_flags & FOLLOW), 1072 ("relookup: symlink found.\n")); 1073 1074 /* ASSERT(dvp == ndp->ni_startdir) */ 1075 if (cnp->cn_flags & SAVESTART) 1076 VREF(dvp); 1077 1078 if ((cnp->cn_flags & LOCKLEAF) == 0) 1079 VOP_UNLOCK(dp, 0); 1080 return (0); 1081 bad: 1082 vput(dp); 1083 *vpp = NULL; 1084 return (error); 1085 } 1086 1087 /* 1088 * Free data allocated by namei(); see namei(9) for details. 1089 */ 1090 void 1091 NDFREE(struct nameidata *ndp, const u_int flags) 1092 { 1093 int unlock_dvp; 1094 int unlock_vp; 1095 1096 unlock_dvp = 0; 1097 unlock_vp = 0; 1098 1099 if (!(flags & NDF_NO_FREE_PNBUF) && 1100 (ndp->ni_cnd.cn_flags & HASBUF)) { 1101 uma_zfree(namei_zone, ndp->ni_cnd.cn_pnbuf); 1102 ndp->ni_cnd.cn_flags &= ~HASBUF; 1103 } 1104 if (!(flags & NDF_NO_VP_UNLOCK) && 1105 (ndp->ni_cnd.cn_flags & LOCKLEAF) && ndp->ni_vp) 1106 unlock_vp = 1; 1107 if (!(flags & NDF_NO_VP_RELE) && ndp->ni_vp) { 1108 if (unlock_vp) { 1109 vput(ndp->ni_vp); 1110 unlock_vp = 0; 1111 } else 1112 vrele(ndp->ni_vp); 1113 ndp->ni_vp = NULL; 1114 } 1115 if (unlock_vp) 1116 VOP_UNLOCK(ndp->ni_vp, 0); 1117 if (!(flags & NDF_NO_DVP_UNLOCK) && 1118 (ndp->ni_cnd.cn_flags & LOCKPARENT) && 1119 ndp->ni_dvp != ndp->ni_vp) 1120 unlock_dvp = 1; 1121 if (!(flags & NDF_NO_DVP_RELE) && 1122 (ndp->ni_cnd.cn_flags & (LOCKPARENT|WANTPARENT))) { 1123 if (unlock_dvp) { 1124 vput(ndp->ni_dvp); 1125 unlock_dvp = 0; 1126 } else 1127 vrele(ndp->ni_dvp); 1128 ndp->ni_dvp = NULL; 1129 } 1130 if (unlock_dvp) 1131 VOP_UNLOCK(ndp->ni_dvp, 0); 1132 if (!(flags & NDF_NO_STARTDIR_RELE) && 1133 (ndp->ni_cnd.cn_flags & SAVESTART)) { 1134 vrele(ndp->ni_startdir); 1135 ndp->ni_startdir = NULL; 1136 } 1137 } 1138 1139 /* 1140 * Determine if there is a suitable alternate filename under the specified 1141 * prefix for the specified path. If the create flag is set, then the 1142 * alternate prefix will be used so long as the parent directory exists. 1143 * This is used by the various compatiblity ABIs so that Linux binaries prefer 1144 * files under /compat/linux for example. The chosen path (whether under 1145 * the prefix or under /) is returned in a kernel malloc'd buffer pointed 1146 * to by pathbuf. The caller is responsible for free'ing the buffer from 1147 * the M_TEMP bucket if one is returned. 1148 */ 1149 int 1150 kern_alternate_path(struct thread *td, const char *prefix, const char *path, 1151 enum uio_seg pathseg, char **pathbuf, int create, int dirfd) 1152 { 1153 struct nameidata nd, ndroot; 1154 char *ptr, *buf, *cp; 1155 size_t len, sz; 1156 int error; 1157 1158 buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 1159 *pathbuf = buf; 1160 1161 /* Copy the prefix into the new pathname as a starting point. */ 1162 len = strlcpy(buf, prefix, MAXPATHLEN); 1163 if (len >= MAXPATHLEN) { 1164 *pathbuf = NULL; 1165 free(buf, M_TEMP); 1166 return (EINVAL); 1167 } 1168 sz = MAXPATHLEN - len; 1169 ptr = buf + len; 1170 1171 /* Append the filename to the prefix. */ 1172 if (pathseg == UIO_SYSSPACE) 1173 error = copystr(path, ptr, sz, &len); 1174 else 1175 error = copyinstr(path, ptr, sz, &len); 1176 1177 if (error) { 1178 *pathbuf = NULL; 1179 free(buf, M_TEMP); 1180 return (error); 1181 } 1182 1183 /* Only use a prefix with absolute pathnames. */ 1184 if (*ptr != '/') { 1185 error = EINVAL; 1186 goto keeporig; 1187 } 1188 1189 if (dirfd != AT_FDCWD) { 1190 /* 1191 * We want the original because the "prefix" is 1192 * included in the already opened dirfd. 1193 */ 1194 bcopy(ptr, buf, len); 1195 return (0); 1196 } 1197 1198 /* 1199 * We know that there is a / somewhere in this pathname. 1200 * Search backwards for it, to find the file's parent dir 1201 * to see if it exists in the alternate tree. If it does, 1202 * and we want to create a file (cflag is set). We don't 1203 * need to worry about the root comparison in this case. 1204 */ 1205 1206 if (create) { 1207 for (cp = &ptr[len] - 1; *cp != '/'; cp--); 1208 *cp = '\0'; 1209 1210 NDINIT(&nd, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, buf, td); 1211 error = namei(&nd); 1212 *cp = '/'; 1213 if (error != 0) 1214 goto keeporig; 1215 } else { 1216 NDINIT(&nd, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, buf, td); 1217 1218 error = namei(&nd); 1219 if (error != 0) 1220 goto keeporig; 1221 1222 /* 1223 * We now compare the vnode of the prefix to the one 1224 * vnode asked. If they resolve to be the same, then we 1225 * ignore the match so that the real root gets used. 1226 * This avoids the problem of traversing "../.." to find the 1227 * root directory and never finding it, because "/" resolves 1228 * to the emulation root directory. This is expensive :-( 1229 */ 1230 NDINIT(&ndroot, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, prefix, 1231 td); 1232 1233 /* We shouldn't ever get an error from this namei(). */ 1234 error = namei(&ndroot); 1235 if (error == 0) { 1236 if (nd.ni_vp == ndroot.ni_vp) 1237 error = ENOENT; 1238 1239 NDFREE(&ndroot, NDF_ONLY_PNBUF); 1240 vrele(ndroot.ni_vp); 1241 VFS_UNLOCK_GIANT(NDHASGIANT(&ndroot)); 1242 } 1243 } 1244 1245 NDFREE(&nd, NDF_ONLY_PNBUF); 1246 vrele(nd.ni_vp); 1247 VFS_UNLOCK_GIANT(NDHASGIANT(&nd)); 1248 1249 keeporig: 1250 /* If there was an error, use the original path name. */ 1251 if (error) 1252 bcopy(ptr, buf, len); 1253 return (error); 1254 }
Cache object: 2c88062aa6aab8100198f24458a521ee
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