Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]
FreeBSD/Linux Kernel Cross Reference
sys/kern/vfs_lookup.c
Version:
- FREEBSD - FREEBSD-13-STABLE - FREEBSD-13-0 - FREEBSD-12-STABLE - FREEBSD-12-0 - FREEBSD-11-STABLE - FREEBSD-11-0 - FREEBSD-10-STABLE - FREEBSD-10-0 - FREEBSD-9-STABLE - FREEBSD-9-0 - FREEBSD-8-STABLE - FREEBSD-8-0 - FREEBSD-7-STABLE - FREEBSD-7-0 - FREEBSD-6-STABLE - FREEBSD-6-0 - FREEBSD-5-STABLE - FREEBSD-5-0 - FREEBSD-4-STABLE - FREEBSD-3-STABLE - FREEBSD22 - l41 - OPENBSD - linux-2.6 - MK84 - PLAN9 - xnu-8792
SearchContext: - none - 3 - 10
SearchContext: - none - 3 - 10
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: releng/9.2/sys/kern/vfs_lookup.c 273415 2014-10-21 20:21:10Z delphij $"); 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, entry, "struct vnode *", "char *", 74 "unsigned long"); 75 SDT_PROBE_DEFINE2(vfs, namei, lookup, return, 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 (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_PROBE(vfs, namei, lookup, entry, dp, cnp->cn_pnbuf, 272 cnp->cn_flags, 0, 0); 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_PROBE(vfs, namei, lookup, return, error, NULL, 0, 302 0, 0); 303 return (error); 304 } 305 vfslocked = (ndp->ni_cnd.cn_flags & GIANTHELD) != 0; 306 ndp->ni_cnd.cn_flags &= ~GIANTHELD; 307 /* 308 * If not a symbolic link, we're done. 309 */ 310 if ((cnp->cn_flags & ISSYMLINK) == 0) { 311 if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) { 312 namei_cleanup_cnp(cnp); 313 } else 314 cnp->cn_flags |= HASBUF; 315 316 if ((cnp->cn_flags & MPSAFE) == 0) { 317 VFS_UNLOCK_GIANT(vfslocked); 318 } else if (vfslocked) 319 ndp->ni_cnd.cn_flags |= GIANTHELD; 320 SDT_PROBE(vfs, namei, lookup, return, 0, ndp->ni_vp, 321 0, 0, 0); 322 return (0); 323 } 324 if (ndp->ni_loopcnt++ >= MAXSYMLINKS) { 325 error = ELOOP; 326 break; 327 } 328 #ifdef MAC 329 if ((cnp->cn_flags & NOMACCHECK) == 0) { 330 error = mac_vnode_check_readlink(td->td_ucred, 331 ndp->ni_vp); 332 if (error) 333 break; 334 } 335 #endif 336 if (ndp->ni_pathlen > 1) 337 cp = uma_zalloc(namei_zone, M_WAITOK); 338 else 339 cp = cnp->cn_pnbuf; 340 aiov.iov_base = cp; 341 aiov.iov_len = MAXPATHLEN; 342 auio.uio_iov = &aiov; 343 auio.uio_iovcnt = 1; 344 auio.uio_offset = 0; 345 auio.uio_rw = UIO_READ; 346 auio.uio_segflg = UIO_SYSSPACE; 347 auio.uio_td = td; 348 auio.uio_resid = MAXPATHLEN; 349 error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred); 350 if (error) { 351 if (ndp->ni_pathlen > 1) 352 uma_zfree(namei_zone, cp); 353 break; 354 } 355 linklen = MAXPATHLEN - auio.uio_resid; 356 if (linklen == 0) { 357 if (ndp->ni_pathlen > 1) 358 uma_zfree(namei_zone, cp); 359 error = ENOENT; 360 break; 361 } 362 if (linklen + ndp->ni_pathlen >= MAXPATHLEN) { 363 if (ndp->ni_pathlen > 1) 364 uma_zfree(namei_zone, cp); 365 error = ENAMETOOLONG; 366 break; 367 } 368 if (ndp->ni_pathlen > 1) { 369 bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen); 370 uma_zfree(namei_zone, cnp->cn_pnbuf); 371 cnp->cn_pnbuf = cp; 372 } else 373 cnp->cn_pnbuf[linklen] = '\0'; 374 ndp->ni_pathlen += linklen; 375 vput(ndp->ni_vp); 376 dp = ndp->ni_dvp; 377 } 378 namei_cleanup_cnp(cnp); 379 vput(ndp->ni_vp); 380 ndp->ni_vp = NULL; 381 vrele(ndp->ni_dvp); 382 VFS_UNLOCK_GIANT(vfslocked); 383 SDT_PROBE(vfs, namei, lookup, return, error, NULL, 0, 0, 0); 384 return (error); 385 } 386 387 static int 388 compute_cn_lkflags(struct mount *mp, int lkflags, int cnflags) 389 { 390 391 if (mp == NULL || ((lkflags & LK_SHARED) && 392 (!(mp->mnt_kern_flag & MNTK_LOOKUP_SHARED) || 393 ((cnflags & ISDOTDOT) && 394 (mp->mnt_kern_flag & MNTK_LOOKUP_EXCL_DOTDOT))))) { 395 lkflags &= ~LK_SHARED; 396 lkflags |= LK_EXCLUSIVE; 397 } 398 return (lkflags); 399 } 400 401 static __inline int 402 needs_exclusive_leaf(struct mount *mp, int flags) 403 { 404 405 /* 406 * Intermediate nodes can use shared locks, we only need to 407 * force an exclusive lock for leaf nodes. 408 */ 409 if ((flags & (ISLASTCN | LOCKLEAF)) != (ISLASTCN | LOCKLEAF)) 410 return (0); 411 412 /* Always use exclusive locks if LOCKSHARED isn't set. */ 413 if (!(flags & LOCKSHARED)) 414 return (1); 415 416 /* 417 * For lookups during open(), if the mount point supports 418 * extended shared operations, then use a shared lock for the 419 * leaf node, otherwise use an exclusive lock. 420 */ 421 if (flags & ISOPEN) { 422 if (mp != NULL && 423 (mp->mnt_kern_flag & MNTK_EXTENDED_SHARED)) 424 return (0); 425 else 426 return (1); 427 } 428 429 /* 430 * Lookup requests outside of open() that specify LOCKSHARED 431 * only need a shared lock on the leaf vnode. 432 */ 433 return (0); 434 } 435 436 /* 437 * Search a pathname. 438 * This is a very central and rather complicated routine. 439 * 440 * The pathname is pointed to by ni_ptr and is of length ni_pathlen. 441 * The starting directory is taken from ni_startdir. The pathname is 442 * descended until done, or a symbolic link is encountered. The variable 443 * ni_more is clear if the path is completed; it is set to one if a 444 * symbolic link needing interpretation is encountered. 445 * 446 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on 447 * whether the name is to be looked up, created, renamed, or deleted. 448 * When CREATE, RENAME, or DELETE is specified, information usable in 449 * creating, renaming, or deleting a directory entry may be calculated. 450 * If flag has LOCKPARENT or'ed into it, the parent directory is returned 451 * locked. If flag has WANTPARENT or'ed into it, the parent directory is 452 * returned unlocked. Otherwise the parent directory is not returned. If 453 * the target of the pathname exists and LOCKLEAF is or'ed into the flag 454 * the target is returned locked, otherwise it is returned unlocked. 455 * When creating or renaming and LOCKPARENT is specified, the target may not 456 * be ".". When deleting and LOCKPARENT is specified, the target may be ".". 457 * 458 * Overall outline of lookup: 459 * 460 * dirloop: 461 * identify next component of name at ndp->ni_ptr 462 * handle degenerate case where name is null string 463 * if .. and crossing mount points and on mounted filesys, find parent 464 * call VOP_LOOKUP routine for next component name 465 * directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set 466 * component vnode returned in ni_vp (if it exists), locked. 467 * if result vnode is mounted on and crossing mount points, 468 * find mounted on vnode 469 * if more components of name, do next level at dirloop 470 * return the answer in ni_vp, locked if LOCKLEAF set 471 * if LOCKPARENT set, return locked parent in ni_dvp 472 * if WANTPARENT set, return unlocked parent in ni_dvp 473 */ 474 int 475 lookup(struct nameidata *ndp) 476 { 477 char *cp; /* pointer into pathname argument */ 478 struct vnode *dp = 0; /* the directory we are searching */ 479 struct vnode *tdp; /* saved dp */ 480 struct mount *mp; /* mount table entry */ 481 struct prison *pr; 482 int docache; /* == 0 do not cache last component */ 483 int wantparent; /* 1 => wantparent or lockparent flag */ 484 int rdonly; /* lookup read-only flag bit */ 485 int error = 0; 486 int dpunlocked = 0; /* dp has already been unlocked */ 487 struct componentname *cnp = &ndp->ni_cnd; 488 int vfslocked; /* VFS Giant state for child */ 489 int dvfslocked; /* VFS Giant state for parent */ 490 int tvfslocked; 491 int lkflags_save; 492 int ni_dvp_unlocked; 493 494 /* 495 * Setup: break out flag bits into variables. 496 */ 497 dvfslocked = (ndp->ni_cnd.cn_flags & GIANTHELD) != 0; 498 vfslocked = 0; 499 ni_dvp_unlocked = 0; 500 ndp->ni_cnd.cn_flags &= ~GIANTHELD; 501 wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT); 502 KASSERT(cnp->cn_nameiop == LOOKUP || wantparent, 503 ("CREATE, DELETE, RENAME require LOCKPARENT or WANTPARENT.")); 504 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE; 505 if (cnp->cn_nameiop == DELETE || 506 (wantparent && cnp->cn_nameiop != CREATE && 507 cnp->cn_nameiop != LOOKUP)) 508 docache = 0; 509 rdonly = cnp->cn_flags & RDONLY; 510 cnp->cn_flags &= ~ISSYMLINK; 511 ndp->ni_dvp = NULL; 512 /* 513 * We use shared locks until we hit the parent of the last cn then 514 * we adjust based on the requesting flags. 515 */ 516 if (lookup_shared) 517 cnp->cn_lkflags = LK_SHARED; 518 else 519 cnp->cn_lkflags = LK_EXCLUSIVE; 520 dp = ndp->ni_startdir; 521 ndp->ni_startdir = NULLVP; 522 vn_lock(dp, 523 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | LK_RETRY, 524 cnp->cn_flags)); 525 526 dirloop: 527 /* 528 * Search a new directory. 529 * 530 * The last component of the filename is left accessible via 531 * cnp->cn_nameptr for callers that need the name. Callers needing 532 * the name set the SAVENAME flag. When done, they assume 533 * responsibility for freeing the pathname buffer. 534 */ 535 cnp->cn_consume = 0; 536 for (cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++) 537 continue; 538 cnp->cn_namelen = cp - cnp->cn_nameptr; 539 if (cnp->cn_namelen > NAME_MAX) { 540 error = ENAMETOOLONG; 541 goto bad; 542 } 543 #ifdef NAMEI_DIAGNOSTIC 544 { char c = *cp; 545 *cp = '\0'; 546 printf("{%s}: ", cnp->cn_nameptr); 547 *cp = c; } 548 #endif 549 ndp->ni_pathlen -= cnp->cn_namelen; 550 ndp->ni_next = cp; 551 552 /* 553 * Replace multiple slashes by a single slash and trailing slashes 554 * by a null. This must be done before VOP_LOOKUP() because some 555 * fs's don't know about trailing slashes. Remember if there were 556 * trailing slashes to handle symlinks, existing non-directories 557 * and non-existing files that won't be directories specially later. 558 */ 559 while (*cp == '/' && (cp[1] == '/' || cp[1] == '\0')) { 560 cp++; 561 ndp->ni_pathlen--; 562 if (*cp == '\0') { 563 *ndp->ni_next = '\0'; 564 cnp->cn_flags |= TRAILINGSLASH; 565 } 566 } 567 ndp->ni_next = cp; 568 569 cnp->cn_flags |= MAKEENTRY; 570 if (*cp == '\0' && docache == 0) 571 cnp->cn_flags &= ~MAKEENTRY; 572 if (cnp->cn_namelen == 2 && 573 cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.') 574 cnp->cn_flags |= ISDOTDOT; 575 else 576 cnp->cn_flags &= ~ISDOTDOT; 577 if (*ndp->ni_next == 0) 578 cnp->cn_flags |= ISLASTCN; 579 else 580 cnp->cn_flags &= ~ISLASTCN; 581 582 if ((cnp->cn_flags & ISLASTCN) != 0 && 583 cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.' && 584 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 585 error = EINVAL; 586 goto bad; 587 } 588 589 /* 590 * Check for degenerate name (e.g. / or "") 591 * which is a way of talking about a directory, 592 * e.g. like "/." or ".". 593 */ 594 if (cnp->cn_nameptr[0] == '\0') { 595 if (dp->v_type != VDIR) { 596 error = ENOTDIR; 597 goto bad; 598 } 599 if (cnp->cn_nameiop != LOOKUP) { 600 error = EISDIR; 601 goto bad; 602 } 603 if (wantparent) { 604 ndp->ni_dvp = dp; 605 VREF(dp); 606 } 607 ndp->ni_vp = dp; 608 609 if (cnp->cn_flags & AUDITVNODE1) 610 AUDIT_ARG_VNODE1(dp); 611 else if (cnp->cn_flags & AUDITVNODE2) 612 AUDIT_ARG_VNODE2(dp); 613 614 if (!(cnp->cn_flags & (LOCKPARENT | LOCKLEAF))) 615 VOP_UNLOCK(dp, 0); 616 /* XXX This should probably move to the top of function. */ 617 if (cnp->cn_flags & SAVESTART) 618 panic("lookup: SAVESTART"); 619 goto success; 620 } 621 622 /* 623 * Handle "..": five special cases. 624 * 0. If doing a capability lookup, return ENOTCAPABLE (this is a 625 * fairly conservative design choice, but it's the only one that we 626 * are satisfied guarantees the property we're looking for). 627 * 1. Return an error if this is the last component of 628 * the name and the operation is DELETE or RENAME. 629 * 2. If at root directory (e.g. after chroot) 630 * or at absolute root directory 631 * then ignore it so can't get out. 632 * 3. If this vnode is the root of a mounted 633 * filesystem, then replace it with the 634 * vnode which was mounted on so we take the 635 * .. in the other filesystem. 636 * 4. If the vnode is the top directory of 637 * the jail or chroot, don't let them out. 638 */ 639 if (cnp->cn_flags & ISDOTDOT) { 640 if (ndp->ni_strictrelative != 0) { 641 error = ENOTCAPABLE; 642 goto bad; 643 } 644 if ((cnp->cn_flags & ISLASTCN) != 0 && 645 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 646 error = EINVAL; 647 goto bad; 648 } 649 for (;;) { 650 for (pr = cnp->cn_cred->cr_prison; pr != NULL; 651 pr = pr->pr_parent) 652 if (dp == pr->pr_root) 653 break; 654 if (dp == ndp->ni_rootdir || 655 dp == ndp->ni_topdir || 656 dp == rootvnode || 657 pr != NULL || 658 ((dp->v_vflag & VV_ROOT) != 0 && 659 (cnp->cn_flags & NOCROSSMOUNT) != 0)) { 660 ndp->ni_dvp = dp; 661 ndp->ni_vp = dp; 662 vfslocked = VFS_LOCK_GIANT(dp->v_mount); 663 VREF(dp); 664 goto nextname; 665 } 666 if ((dp->v_vflag & VV_ROOT) == 0) 667 break; 668 if (dp->v_iflag & VI_DOOMED) { /* forced unmount */ 669 error = ENOENT; 670 goto bad; 671 } 672 tdp = dp; 673 dp = dp->v_mount->mnt_vnodecovered; 674 tvfslocked = dvfslocked; 675 dvfslocked = VFS_LOCK_GIANT(dp->v_mount); 676 VREF(dp); 677 vput(tdp); 678 VFS_UNLOCK_GIANT(tvfslocked); 679 vn_lock(dp, 680 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | 681 LK_RETRY, ISDOTDOT)); 682 } 683 } 684 685 /* 686 * We now have a segment name to search for, and a directory to search. 687 */ 688 unionlookup: 689 #ifdef MAC 690 if ((cnp->cn_flags & NOMACCHECK) == 0) { 691 error = mac_vnode_check_lookup(cnp->cn_thread->td_ucred, dp, 692 cnp); 693 if (error) 694 goto bad; 695 } 696 #endif 697 ndp->ni_dvp = dp; 698 ndp->ni_vp = NULL; 699 ASSERT_VOP_LOCKED(dp, "lookup"); 700 VNASSERT(vfslocked == 0, dp, ("lookup: vfslocked %d", vfslocked)); 701 /* 702 * If we have a shared lock we may need to upgrade the lock for the 703 * last operation. 704 */ 705 if (dp != vp_crossmp && 706 VOP_ISLOCKED(dp) == LK_SHARED && 707 (cnp->cn_flags & ISLASTCN) && (cnp->cn_flags & LOCKPARENT)) 708 vn_lock(dp, LK_UPGRADE|LK_RETRY); 709 if ((dp->v_iflag & VI_DOOMED) != 0) { 710 error = ENOENT; 711 goto bad; 712 } 713 /* 714 * If we're looking up the last component and we need an exclusive 715 * lock, adjust our lkflags. 716 */ 717 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags)) 718 cnp->cn_lkflags = LK_EXCLUSIVE; 719 #ifdef NAMEI_DIAGNOSTIC 720 vprint("lookup in", dp); 721 #endif 722 lkflags_save = cnp->cn_lkflags; 723 cnp->cn_lkflags = compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags, 724 cnp->cn_flags); 725 if ((error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp)) != 0) { 726 cnp->cn_lkflags = lkflags_save; 727 KASSERT(ndp->ni_vp == NULL, ("leaf should be empty")); 728 #ifdef NAMEI_DIAGNOSTIC 729 printf("not found\n"); 730 #endif 731 if ((error == ENOENT) && 732 (dp->v_vflag & VV_ROOT) && (dp->v_mount != NULL) && 733 (dp->v_mount->mnt_flag & MNT_UNION)) { 734 tdp = dp; 735 dp = dp->v_mount->mnt_vnodecovered; 736 tvfslocked = dvfslocked; 737 dvfslocked = VFS_LOCK_GIANT(dp->v_mount); 738 VREF(dp); 739 vput(tdp); 740 VFS_UNLOCK_GIANT(tvfslocked); 741 vn_lock(dp, 742 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | 743 LK_RETRY, cnp->cn_flags)); 744 goto unionlookup; 745 } 746 747 if (error != EJUSTRETURN) 748 goto bad; 749 /* 750 * At this point, we know we're at the end of the 751 * pathname. If creating / renaming, we can consider 752 * allowing the file or directory to be created / renamed, 753 * provided we're not on a read-only filesystem. 754 */ 755 if (rdonly) { 756 error = EROFS; 757 goto bad; 758 } 759 /* trailing slash only allowed for directories */ 760 if ((cnp->cn_flags & TRAILINGSLASH) && 761 !(cnp->cn_flags & WILLBEDIR)) { 762 error = ENOENT; 763 goto bad; 764 } 765 if ((cnp->cn_flags & LOCKPARENT) == 0) 766 VOP_UNLOCK(dp, 0); 767 /* 768 * We return with ni_vp NULL to indicate that the entry 769 * doesn't currently exist, leaving a pointer to the 770 * (possibly locked) directory vnode in ndp->ni_dvp. 771 */ 772 if (cnp->cn_flags & SAVESTART) { 773 ndp->ni_startdir = ndp->ni_dvp; 774 VREF(ndp->ni_startdir); 775 } 776 goto success; 777 } else 778 cnp->cn_lkflags = lkflags_save; 779 #ifdef NAMEI_DIAGNOSTIC 780 printf("found\n"); 781 #endif 782 /* 783 * Take into account any additional components consumed by 784 * the underlying filesystem. 785 */ 786 if (cnp->cn_consume > 0) { 787 cnp->cn_nameptr += cnp->cn_consume; 788 ndp->ni_next += cnp->cn_consume; 789 ndp->ni_pathlen -= cnp->cn_consume; 790 cnp->cn_consume = 0; 791 } 792 793 dp = ndp->ni_vp; 794 vfslocked = VFS_LOCK_GIANT(dp->v_mount); 795 796 /* 797 * Check to see if the vnode has been mounted on; 798 * if so find the root of the mounted filesystem. 799 */ 800 while (dp->v_type == VDIR && (mp = dp->v_mountedhere) && 801 (cnp->cn_flags & NOCROSSMOUNT) == 0) { 802 if (vfs_busy(mp, 0)) 803 continue; 804 vput(dp); 805 VFS_UNLOCK_GIANT(vfslocked); 806 vfslocked = VFS_LOCK_GIANT(mp); 807 if (dp != ndp->ni_dvp) 808 vput(ndp->ni_dvp); 809 else 810 vrele(ndp->ni_dvp); 811 VFS_UNLOCK_GIANT(dvfslocked); 812 dvfslocked = 0; 813 vref(vp_crossmp); 814 ndp->ni_dvp = vp_crossmp; 815 error = VFS_ROOT(mp, compute_cn_lkflags(mp, cnp->cn_lkflags, 816 cnp->cn_flags), &tdp); 817 vfs_unbusy(mp); 818 if (vn_lock(vp_crossmp, LK_SHARED | LK_NOWAIT)) 819 panic("vp_crossmp exclusively locked or reclaimed"); 820 if (error) { 821 dpunlocked = 1; 822 goto bad2; 823 } 824 ndp->ni_vp = dp = tdp; 825 } 826 827 /* 828 * Check for symbolic link 829 */ 830 if ((dp->v_type == VLNK) && 831 ((cnp->cn_flags & FOLLOW) || (cnp->cn_flags & TRAILINGSLASH) || 832 *ndp->ni_next == '/')) { 833 cnp->cn_flags |= ISSYMLINK; 834 if (dp->v_iflag & VI_DOOMED) { 835 /* 836 * We can't know whether the directory was mounted with 837 * NOSYMFOLLOW, so we can't follow safely. 838 */ 839 error = ENOENT; 840 goto bad2; 841 } 842 if (dp->v_mount->mnt_flag & MNT_NOSYMFOLLOW) { 843 error = EACCES; 844 goto bad2; 845 } 846 /* 847 * Symlink code always expects an unlocked dvp. 848 */ 849 if (ndp->ni_dvp != ndp->ni_vp) { 850 VOP_UNLOCK(ndp->ni_dvp, 0); 851 ni_dvp_unlocked = 1; 852 } 853 goto success; 854 } 855 856 nextname: 857 /* 858 * Not a symbolic link that we will follow. Continue with the 859 * next component if there is any; otherwise, we're done. 860 */ 861 KASSERT((cnp->cn_flags & ISLASTCN) || *ndp->ni_next == '/', 862 ("lookup: invalid path state.")); 863 if (*ndp->ni_next == '/') { 864 cnp->cn_nameptr = ndp->ni_next; 865 while (*cnp->cn_nameptr == '/') { 866 cnp->cn_nameptr++; 867 ndp->ni_pathlen--; 868 } 869 if (ndp->ni_dvp != dp) 870 vput(ndp->ni_dvp); 871 else 872 vrele(ndp->ni_dvp); 873 VFS_UNLOCK_GIANT(dvfslocked); 874 dvfslocked = vfslocked; /* dp becomes dvp in dirloop */ 875 vfslocked = 0; 876 goto dirloop; 877 } 878 /* 879 * If we're processing a path with a trailing slash, 880 * check that the end result is a directory. 881 */ 882 if ((cnp->cn_flags & TRAILINGSLASH) && dp->v_type != VDIR) { 883 error = ENOTDIR; 884 goto bad2; 885 } 886 /* 887 * Disallow directory write attempts on read-only filesystems. 888 */ 889 if (rdonly && 890 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 891 error = EROFS; 892 goto bad2; 893 } 894 if (cnp->cn_flags & SAVESTART) { 895 ndp->ni_startdir = ndp->ni_dvp; 896 VREF(ndp->ni_startdir); 897 } 898 if (!wantparent) { 899 ni_dvp_unlocked = 2; 900 if (ndp->ni_dvp != dp) 901 vput(ndp->ni_dvp); 902 else 903 vrele(ndp->ni_dvp); 904 VFS_UNLOCK_GIANT(dvfslocked); 905 dvfslocked = 0; 906 } else if ((cnp->cn_flags & LOCKPARENT) == 0 && ndp->ni_dvp != dp) { 907 VOP_UNLOCK(ndp->ni_dvp, 0); 908 ni_dvp_unlocked = 1; 909 } 910 911 if (cnp->cn_flags & AUDITVNODE1) 912 AUDIT_ARG_VNODE1(dp); 913 else if (cnp->cn_flags & AUDITVNODE2) 914 AUDIT_ARG_VNODE2(dp); 915 916 if ((cnp->cn_flags & LOCKLEAF) == 0) 917 VOP_UNLOCK(dp, 0); 918 success: 919 /* 920 * Because of lookup_shared we may have the vnode shared locked, but 921 * the caller may want it to be exclusively locked. 922 */ 923 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags) && 924 VOP_ISLOCKED(dp) != LK_EXCLUSIVE) { 925 vn_lock(dp, LK_UPGRADE | LK_RETRY); 926 if (dp->v_iflag & VI_DOOMED) { 927 error = ENOENT; 928 goto bad2; 929 } 930 } 931 if (vfslocked && dvfslocked) 932 VFS_UNLOCK_GIANT(dvfslocked); /* Only need one */ 933 if (vfslocked || dvfslocked) 934 ndp->ni_cnd.cn_flags |= GIANTHELD; 935 return (0); 936 937 bad2: 938 if (ni_dvp_unlocked != 2) { 939 if (dp != ndp->ni_dvp && !ni_dvp_unlocked) 940 vput(ndp->ni_dvp); 941 else 942 vrele(ndp->ni_dvp); 943 } 944 bad: 945 if (!dpunlocked) 946 vput(dp); 947 VFS_UNLOCK_GIANT(vfslocked); 948 VFS_UNLOCK_GIANT(dvfslocked); 949 ndp->ni_cnd.cn_flags &= ~GIANTHELD; 950 ndp->ni_vp = NULL; 951 return (error); 952 } 953 954 /* 955 * relookup - lookup a path name component 956 * Used by lookup to re-acquire things. 957 */ 958 int 959 relookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp) 960 { 961 struct vnode *dp = 0; /* the directory we are searching */ 962 int wantparent; /* 1 => wantparent or lockparent flag */ 963 int rdonly; /* lookup read-only flag bit */ 964 int error = 0; 965 966 KASSERT(cnp->cn_flags & ISLASTCN, 967 ("relookup: Not given last component.")); 968 /* 969 * Setup: break out flag bits into variables. 970 */ 971 wantparent = cnp->cn_flags & (LOCKPARENT|WANTPARENT); 972 KASSERT(wantparent, ("relookup: parent not wanted.")); 973 rdonly = cnp->cn_flags & RDONLY; 974 cnp->cn_flags &= ~ISSYMLINK; 975 dp = dvp; 976 cnp->cn_lkflags = LK_EXCLUSIVE; 977 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY); 978 979 /* 980 * Search a new directory. 981 * 982 * The last component of the filename is left accessible via 983 * cnp->cn_nameptr for callers that need the name. Callers needing 984 * the name set the SAVENAME flag. When done, they assume 985 * responsibility for freeing the pathname buffer. 986 */ 987 #ifdef NAMEI_DIAGNOSTIC 988 printf("{%s}: ", cnp->cn_nameptr); 989 #endif 990 991 /* 992 * Check for "" which represents the root directory after slash 993 * removal. 994 */ 995 if (cnp->cn_nameptr[0] == '\0') { 996 /* 997 * Support only LOOKUP for "/" because lookup() 998 * can't succeed for CREATE, DELETE and RENAME. 999 */ 1000 KASSERT(cnp->cn_nameiop == LOOKUP, ("nameiop must be LOOKUP")); 1001 KASSERT(dp->v_type == VDIR, ("dp is not a directory")); 1002 1003 if (!(cnp->cn_flags & LOCKLEAF)) 1004 VOP_UNLOCK(dp, 0); 1005 *vpp = dp; 1006 /* XXX This should probably move to the top of function. */ 1007 if (cnp->cn_flags & SAVESTART) 1008 panic("lookup: SAVESTART"); 1009 return (0); 1010 } 1011 1012 if (cnp->cn_flags & ISDOTDOT) 1013 panic ("relookup: lookup on dot-dot"); 1014 1015 /* 1016 * We now have a segment name to search for, and a directory to search. 1017 */ 1018 #ifdef NAMEI_DIAGNOSTIC 1019 vprint("search in:", dp); 1020 #endif 1021 if ((error = VOP_LOOKUP(dp, vpp, cnp)) != 0) { 1022 KASSERT(*vpp == NULL, ("leaf should be empty")); 1023 if (error != EJUSTRETURN) 1024 goto bad; 1025 /* 1026 * If creating and at end of pathname, then can consider 1027 * allowing file to be created. 1028 */ 1029 if (rdonly) { 1030 error = EROFS; 1031 goto bad; 1032 } 1033 /* ASSERT(dvp == ndp->ni_startdir) */ 1034 if (cnp->cn_flags & SAVESTART) 1035 VREF(dvp); 1036 if ((cnp->cn_flags & LOCKPARENT) == 0) 1037 VOP_UNLOCK(dp, 0); 1038 /* 1039 * We return with ni_vp NULL to indicate that the entry 1040 * doesn't currently exist, leaving a pointer to the 1041 * (possibly locked) directory vnode in ndp->ni_dvp. 1042 */ 1043 return (0); 1044 } 1045 1046 dp = *vpp; 1047 1048 /* 1049 * Disallow directory write attempts on read-only filesystems. 1050 */ 1051 if (rdonly && 1052 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 1053 if (dvp == dp) 1054 vrele(dvp); 1055 else 1056 vput(dvp); 1057 error = EROFS; 1058 goto bad; 1059 } 1060 /* 1061 * Set the parent lock/ref state to the requested state. 1062 */ 1063 if ((cnp->cn_flags & LOCKPARENT) == 0 && dvp != dp) { 1064 if (wantparent) 1065 VOP_UNLOCK(dvp, 0); 1066 else 1067 vput(dvp); 1068 } else if (!wantparent) 1069 vrele(dvp); 1070 /* 1071 * Check for symbolic link 1072 */ 1073 KASSERT(dp->v_type != VLNK || !(cnp->cn_flags & FOLLOW), 1074 ("relookup: symlink found.\n")); 1075 1076 /* ASSERT(dvp == ndp->ni_startdir) */ 1077 if (cnp->cn_flags & SAVESTART) 1078 VREF(dvp); 1079 1080 if ((cnp->cn_flags & LOCKLEAF) == 0) 1081 VOP_UNLOCK(dp, 0); 1082 return (0); 1083 bad: 1084 vput(dp); 1085 *vpp = NULL; 1086 return (error); 1087 } 1088 1089 /* 1090 * Free data allocated by namei(); see namei(9) for details. 1091 */ 1092 void 1093 NDFREE(struct nameidata *ndp, const u_int flags) 1094 { 1095 int unlock_dvp; 1096 int unlock_vp; 1097 1098 unlock_dvp = 0; 1099 unlock_vp = 0; 1100 1101 if (!(flags & NDF_NO_FREE_PNBUF) && 1102 (ndp->ni_cnd.cn_flags & HASBUF)) { 1103 uma_zfree(namei_zone, ndp->ni_cnd.cn_pnbuf); 1104 ndp->ni_cnd.cn_flags &= ~HASBUF; 1105 } 1106 if (!(flags & NDF_NO_VP_UNLOCK) && 1107 (ndp->ni_cnd.cn_flags & LOCKLEAF) && ndp->ni_vp) 1108 unlock_vp = 1; 1109 if (!(flags & NDF_NO_VP_RELE) && ndp->ni_vp) { 1110 if (unlock_vp) { 1111 vput(ndp->ni_vp); 1112 unlock_vp = 0; 1113 } else 1114 vrele(ndp->ni_vp); 1115 ndp->ni_vp = NULL; 1116 } 1117 if (unlock_vp) 1118 VOP_UNLOCK(ndp->ni_vp, 0); 1119 if (!(flags & NDF_NO_DVP_UNLOCK) && 1120 (ndp->ni_cnd.cn_flags & LOCKPARENT) && 1121 ndp->ni_dvp != ndp->ni_vp) 1122 unlock_dvp = 1; 1123 if (!(flags & NDF_NO_DVP_RELE) && 1124 (ndp->ni_cnd.cn_flags & (LOCKPARENT|WANTPARENT))) { 1125 if (unlock_dvp) { 1126 vput(ndp->ni_dvp); 1127 unlock_dvp = 0; 1128 } else 1129 vrele(ndp->ni_dvp); 1130 ndp->ni_dvp = NULL; 1131 } 1132 if (unlock_dvp) 1133 VOP_UNLOCK(ndp->ni_dvp, 0); 1134 if (!(flags & NDF_NO_STARTDIR_RELE) && 1135 (ndp->ni_cnd.cn_flags & SAVESTART)) { 1136 vrele(ndp->ni_startdir); 1137 ndp->ni_startdir = NULL; 1138 } 1139 } 1140 1141 /* 1142 * Determine if there is a suitable alternate filename under the specified 1143 * prefix for the specified path. If the create flag is set, then the 1144 * alternate prefix will be used so long as the parent directory exists. 1145 * This is used by the various compatiblity ABIs so that Linux binaries prefer 1146 * files under /compat/linux for example. The chosen path (whether under 1147 * the prefix or under /) is returned in a kernel malloc'd buffer pointed 1148 * to by pathbuf. The caller is responsible for free'ing the buffer from 1149 * the M_TEMP bucket if one is returned. 1150 */ 1151 int 1152 kern_alternate_path(struct thread *td, const char *prefix, const char *path, 1153 enum uio_seg pathseg, char **pathbuf, int create, int dirfd) 1154 { 1155 struct nameidata nd, ndroot; 1156 char *ptr, *buf, *cp; 1157 size_t len, sz; 1158 int error; 1159 1160 buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 1161 *pathbuf = buf; 1162 1163 /* Copy the prefix into the new pathname as a starting point. */ 1164 len = strlcpy(buf, prefix, MAXPATHLEN); 1165 if (len >= MAXPATHLEN) { 1166 *pathbuf = NULL; 1167 free(buf, M_TEMP); 1168 return (EINVAL); 1169 } 1170 sz = MAXPATHLEN - len; 1171 ptr = buf + len; 1172 1173 /* Append the filename to the prefix. */ 1174 if (pathseg == UIO_SYSSPACE) 1175 error = copystr(path, ptr, sz, &len); 1176 else 1177 error = copyinstr(path, ptr, sz, &len); 1178 1179 if (error) { 1180 *pathbuf = NULL; 1181 free(buf, M_TEMP); 1182 return (error); 1183 } 1184 1185 /* Only use a prefix with absolute pathnames. */ 1186 if (*ptr != '/') { 1187 error = EINVAL; 1188 goto keeporig; 1189 } 1190 1191 if (dirfd != AT_FDCWD) { 1192 /* 1193 * We want the original because the "prefix" is 1194 * included in the already opened dirfd. 1195 */ 1196 bcopy(ptr, buf, len); 1197 return (0); 1198 } 1199 1200 /* 1201 * We know that there is a / somewhere in this pathname. 1202 * Search backwards for it, to find the file's parent dir 1203 * to see if it exists in the alternate tree. If it does, 1204 * and we want to create a file (cflag is set). We don't 1205 * need to worry about the root comparison in this case. 1206 */ 1207 1208 if (create) { 1209 for (cp = &ptr[len] - 1; *cp != '/'; cp--); 1210 *cp = '\0'; 1211 1212 NDINIT(&nd, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, buf, td); 1213 error = namei(&nd); 1214 *cp = '/'; 1215 if (error != 0) 1216 goto keeporig; 1217 } else { 1218 NDINIT(&nd, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, buf, td); 1219 1220 error = namei(&nd); 1221 if (error != 0) 1222 goto keeporig; 1223 1224 /* 1225 * We now compare the vnode of the prefix to the one 1226 * vnode asked. If they resolve to be the same, then we 1227 * ignore the match so that the real root gets used. 1228 * This avoids the problem of traversing "../.." to find the 1229 * root directory and never finding it, because "/" resolves 1230 * to the emulation root directory. This is expensive :-( 1231 */ 1232 NDINIT(&ndroot, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, prefix, 1233 td); 1234 1235 /* We shouldn't ever get an error from this namei(). */ 1236 error = namei(&ndroot); 1237 if (error == 0) { 1238 if (nd.ni_vp == ndroot.ni_vp) 1239 error = ENOENT; 1240 1241 NDFREE(&ndroot, NDF_ONLY_PNBUF); 1242 vrele(ndroot.ni_vp); 1243 VFS_UNLOCK_GIANT(NDHASGIANT(&ndroot)); 1244 } 1245 } 1246 1247 NDFREE(&nd, NDF_ONLY_PNBUF); 1248 vrele(nd.ni_vp); 1249 VFS_UNLOCK_GIANT(NDHASGIANT(&nd)); 1250 1251 keeporig: 1252 /* If there was an error, use the original path name. */ 1253 if (error) 1254 bcopy(ptr, buf, len); 1255 return (error); 1256 }
Cache object: 88151f6d1fb9894ead6cbbff3fffb52a
[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]