FreeBSD/Linux Kernel Cross Reference
sys/kern/vfs_lookup.c
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/9.0/sys/kern/vfs_lookup.c 224810 2011-08-13 09:21:16Z jonathan $");
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 int
125 namei(struct nameidata *ndp)
126 {
127 struct filedesc *fdp; /* pointer to file descriptor state */
128 char *cp; /* pointer into pathname argument */
129 struct vnode *dp; /* the directory we are searching */
130 struct iovec aiov; /* uio for reading symbolic links */
131 struct uio auio;
132 int error, linklen;
133 struct componentname *cnp = &ndp->ni_cnd;
134 struct thread *td = cnp->cn_thread;
135 struct proc *p = td->td_proc;
136 int vfslocked;
137
138 KASSERT((cnp->cn_flags & MPSAFE) != 0 || mtx_owned(&Giant) != 0,
139 ("NOT MPSAFE and Giant not held"));
140 ndp->ni_cnd.cn_cred = ndp->ni_cnd.cn_thread->td_ucred;
141 KASSERT(cnp->cn_cred && p, ("namei: bad cred/proc"));
142 KASSERT((cnp->cn_nameiop & (~OPMASK)) == 0,
143 ("namei: nameiop contaminated with flags"));
144 KASSERT((cnp->cn_flags & OPMASK) == 0,
145 ("namei: flags contaminated with nameiops"));
146 if (!lookup_shared)
147 cnp->cn_flags &= ~LOCKSHARED;
148 fdp = p->p_fd;
149
150 /* We will set this ourselves if we need it. */
151 cnp->cn_flags &= ~TRAILINGSLASH;
152
153 /*
154 * Get a buffer for the name to be translated, and copy the
155 * name into the buffer.
156 */
157 if ((cnp->cn_flags & HASBUF) == 0)
158 cnp->cn_pnbuf = uma_zalloc(namei_zone, M_WAITOK);
159 if (ndp->ni_segflg == UIO_SYSSPACE)
160 error = copystr(ndp->ni_dirp, cnp->cn_pnbuf,
161 MAXPATHLEN, (size_t *)&ndp->ni_pathlen);
162 else
163 error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf,
164 MAXPATHLEN, (size_t *)&ndp->ni_pathlen);
165
166 if (error == 0) {
167 /*
168 * If we are auditing the kernel pathname, save the user
169 * pathname.
170 */
171 if (cnp->cn_flags & AUDITVNODE1)
172 AUDIT_ARG_UPATH1(td, cnp->cn_pnbuf);
173 if (cnp->cn_flags & AUDITVNODE2)
174 AUDIT_ARG_UPATH2(td, cnp->cn_pnbuf);
175 }
176
177 /*
178 * Don't allow empty pathnames.
179 */
180 if (!error && *cnp->cn_pnbuf == '\0')
181 error = ENOENT;
182
183 #ifdef CAPABILITY_MODE
184 /*
185 * In capability mode, lookups must be "strictly relative" (i.e.
186 * not an absolute path, and not containing '..' components) to
187 * a real file descriptor, not the pseudo-descriptor AT_FDCWD.
188 */
189 if (IN_CAPABILITY_MODE(td)) {
190 ndp->ni_strictrelative = 1;
191 if (ndp->ni_dirfd == AT_FDCWD)
192 error = ECAPMODE;
193 }
194 #endif
195 if (error) {
196 uma_zfree(namei_zone, cnp->cn_pnbuf);
197 #ifdef DIAGNOSTIC
198 cnp->cn_pnbuf = NULL;
199 cnp->cn_nameptr = NULL;
200 #endif
201 ndp->ni_vp = NULL;
202 return (error);
203 }
204 ndp->ni_loopcnt = 0;
205 #ifdef KTRACE
206 if (KTRPOINT(td, KTR_NAMEI)) {
207 KASSERT(cnp->cn_thread == curthread,
208 ("namei not using curthread"));
209 ktrnamei(cnp->cn_pnbuf);
210 }
211 #endif
212 /*
213 * Get starting point for the translation.
214 */
215 FILEDESC_SLOCK(fdp);
216 ndp->ni_rootdir = fdp->fd_rdir;
217 ndp->ni_topdir = fdp->fd_jdir;
218
219 dp = NULL;
220 if (cnp->cn_pnbuf[0] != '/') {
221 if (ndp->ni_startdir != NULL) {
222 dp = ndp->ni_startdir;
223 error = 0;
224 } else if (ndp->ni_dirfd != AT_FDCWD) {
225 if (cnp->cn_flags & AUDITVNODE1)
226 AUDIT_ARG_ATFD1(ndp->ni_dirfd);
227 if (cnp->cn_flags & AUDITVNODE2)
228 AUDIT_ARG_ATFD2(ndp->ni_dirfd);
229 error = fgetvp_rights(td, ndp->ni_dirfd,
230 ndp->ni_rightsneeded | CAP_LOOKUP,
231 &(ndp->ni_baserights), &dp);
232 #ifdef CAPABILITIES
233 /*
234 * Lookups relative to a capability must also be
235 * strictly relative.
236 *
237 * Note that a capability with rights CAP_MASK_VALID
238 * is treated exactly like a regular file descriptor.
239 */
240 if (ndp->ni_baserights != CAP_MASK_VALID)
241 ndp->ni_strictrelative = 1;
242 #endif
243 }
244 if (error != 0 || dp != NULL) {
245 FILEDESC_SUNLOCK(fdp);
246 if (error == 0 && dp->v_type != VDIR) {
247 vfslocked = VFS_LOCK_GIANT(dp->v_mount);
248 vrele(dp);
249 VFS_UNLOCK_GIANT(vfslocked);
250 error = ENOTDIR;
251 }
252 }
253 if (error) {
254 uma_zfree(namei_zone, cnp->cn_pnbuf);
255 #ifdef DIAGNOSTIC
256 cnp->cn_pnbuf = NULL;
257 cnp->cn_nameptr = NULL;
258 #endif
259 return (error);
260 }
261 }
262 if (dp == NULL) {
263 dp = fdp->fd_cdir;
264 VREF(dp);
265 FILEDESC_SUNLOCK(fdp);
266 if (ndp->ni_startdir != NULL) {
267 vfslocked = VFS_LOCK_GIANT(ndp->ni_startdir->v_mount);
268 vrele(ndp->ni_startdir);
269 VFS_UNLOCK_GIANT(vfslocked);
270 }
271 }
272 SDT_PROBE(vfs, namei, lookup, entry, dp, cnp->cn_pnbuf,
273 cnp->cn_flags, 0, 0);
274 vfslocked = VFS_LOCK_GIANT(dp->v_mount);
275 for (;;) {
276 /*
277 * Check if root directory should replace current directory.
278 * Done at start of translation and after symbolic link.
279 */
280 cnp->cn_nameptr = cnp->cn_pnbuf;
281 if (*(cnp->cn_nameptr) == '/') {
282 vrele(dp);
283 VFS_UNLOCK_GIANT(vfslocked);
284 if (ndp->ni_strictrelative != 0)
285 return (ENOTCAPABLE);
286 while (*(cnp->cn_nameptr) == '/') {
287 cnp->cn_nameptr++;
288 ndp->ni_pathlen--;
289 }
290 dp = ndp->ni_rootdir;
291 vfslocked = VFS_LOCK_GIANT(dp->v_mount);
292 VREF(dp);
293 }
294 if (vfslocked)
295 ndp->ni_cnd.cn_flags |= GIANTHELD;
296 ndp->ni_startdir = dp;
297 error = lookup(ndp);
298 if (error) {
299 uma_zfree(namei_zone, cnp->cn_pnbuf);
300 #ifdef DIAGNOSTIC
301 cnp->cn_pnbuf = NULL;
302 cnp->cn_nameptr = NULL;
303 #endif
304 SDT_PROBE(vfs, namei, lookup, return, error, NULL, 0,
305 0, 0);
306 return (error);
307 }
308 vfslocked = (ndp->ni_cnd.cn_flags & GIANTHELD) != 0;
309 ndp->ni_cnd.cn_flags &= ~GIANTHELD;
310 /*
311 * If not a symbolic link, we're done.
312 */
313 if ((cnp->cn_flags & ISSYMLINK) == 0) {
314 if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) {
315 uma_zfree(namei_zone, cnp->cn_pnbuf);
316 #ifdef DIAGNOSTIC
317 cnp->cn_pnbuf = NULL;
318 cnp->cn_nameptr = NULL;
319 #endif
320 } else
321 cnp->cn_flags |= HASBUF;
322
323 if ((cnp->cn_flags & MPSAFE) == 0) {
324 VFS_UNLOCK_GIANT(vfslocked);
325 } else if (vfslocked)
326 ndp->ni_cnd.cn_flags |= GIANTHELD;
327 SDT_PROBE(vfs, namei, lookup, return, 0, ndp->ni_vp,
328 0, 0, 0);
329 return (0);
330 }
331 if (ndp->ni_loopcnt++ >= MAXSYMLINKS) {
332 error = ELOOP;
333 break;
334 }
335 #ifdef MAC
336 if ((cnp->cn_flags & NOMACCHECK) == 0) {
337 error = mac_vnode_check_readlink(td->td_ucred,
338 ndp->ni_vp);
339 if (error)
340 break;
341 }
342 #endif
343 if (ndp->ni_pathlen > 1)
344 cp = uma_zalloc(namei_zone, M_WAITOK);
345 else
346 cp = cnp->cn_pnbuf;
347 aiov.iov_base = cp;
348 aiov.iov_len = MAXPATHLEN;
349 auio.uio_iov = &aiov;
350 auio.uio_iovcnt = 1;
351 auio.uio_offset = 0;
352 auio.uio_rw = UIO_READ;
353 auio.uio_segflg = UIO_SYSSPACE;
354 auio.uio_td = (struct thread *)0;
355 auio.uio_resid = MAXPATHLEN;
356 error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred);
357 if (error) {
358 if (ndp->ni_pathlen > 1)
359 uma_zfree(namei_zone, cp);
360 break;
361 }
362 linklen = MAXPATHLEN - auio.uio_resid;
363 if (linklen == 0) {
364 if (ndp->ni_pathlen > 1)
365 uma_zfree(namei_zone, cp);
366 error = ENOENT;
367 break;
368 }
369 if (linklen + ndp->ni_pathlen >= MAXPATHLEN) {
370 if (ndp->ni_pathlen > 1)
371 uma_zfree(namei_zone, cp);
372 error = ENAMETOOLONG;
373 break;
374 }
375 if (ndp->ni_pathlen > 1) {
376 bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen);
377 uma_zfree(namei_zone, cnp->cn_pnbuf);
378 cnp->cn_pnbuf = cp;
379 } else
380 cnp->cn_pnbuf[linklen] = '\0';
381 ndp->ni_pathlen += linklen;
382 vput(ndp->ni_vp);
383 dp = ndp->ni_dvp;
384 }
385 uma_zfree(namei_zone, cnp->cn_pnbuf);
386 #ifdef DIAGNOSTIC
387 cnp->cn_pnbuf = NULL;
388 cnp->cn_nameptr = NULL;
389 #endif
390 vput(ndp->ni_vp);
391 ndp->ni_vp = NULL;
392 vrele(ndp->ni_dvp);
393 VFS_UNLOCK_GIANT(vfslocked);
394 SDT_PROBE(vfs, namei, lookup, return, error, NULL, 0, 0, 0);
395 return (error);
396 }
397
398 static int
399 compute_cn_lkflags(struct mount *mp, int lkflags)
400 {
401
402 if (mp == NULL ||
403 ((lkflags & LK_SHARED) && !(mp->mnt_kern_flag & MNTK_LOOKUP_SHARED))) {
404 lkflags &= ~LK_SHARED;
405 lkflags |= LK_EXCLUSIVE;
406 }
407 return (lkflags);
408 }
409
410 static __inline int
411 needs_exclusive_leaf(struct mount *mp, int flags)
412 {
413
414 /*
415 * Intermediate nodes can use shared locks, we only need to
416 * force an exclusive lock for leaf nodes.
417 */
418 if ((flags & (ISLASTCN | LOCKLEAF)) != (ISLASTCN | LOCKLEAF))
419 return (0);
420
421 /* Always use exclusive locks if LOCKSHARED isn't set. */
422 if (!(flags & LOCKSHARED))
423 return (1);
424
425 /*
426 * For lookups during open(), if the mount point supports
427 * extended shared operations, then use a shared lock for the
428 * leaf node, otherwise use an exclusive lock.
429 */
430 if (flags & ISOPEN) {
431 if (mp != NULL &&
432 (mp->mnt_kern_flag & MNTK_EXTENDED_SHARED))
433 return (0);
434 else
435 return (1);
436 }
437
438 /*
439 * Lookup requests outside of open() that specify LOCKSHARED
440 * only need a shared lock on the leaf vnode.
441 */
442 return (0);
443 }
444
445 /*
446 * Search a pathname.
447 * This is a very central and rather complicated routine.
448 *
449 * The pathname is pointed to by ni_ptr and is of length ni_pathlen.
450 * The starting directory is taken from ni_startdir. The pathname is
451 * descended until done, or a symbolic link is encountered. The variable
452 * ni_more is clear if the path is completed; it is set to one if a
453 * symbolic link needing interpretation is encountered.
454 *
455 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on
456 * whether the name is to be looked up, created, renamed, or deleted.
457 * When CREATE, RENAME, or DELETE is specified, information usable in
458 * creating, renaming, or deleting a directory entry may be calculated.
459 * If flag has LOCKPARENT or'ed into it, the parent directory is returned
460 * locked. If flag has WANTPARENT or'ed into it, the parent directory is
461 * returned unlocked. Otherwise the parent directory is not returned. If
462 * the target of the pathname exists and LOCKLEAF is or'ed into the flag
463 * the target is returned locked, otherwise it is returned unlocked.
464 * When creating or renaming and LOCKPARENT is specified, the target may not
465 * be ".". When deleting and LOCKPARENT is specified, the target may be ".".
466 *
467 * Overall outline of lookup:
468 *
469 * dirloop:
470 * identify next component of name at ndp->ni_ptr
471 * handle degenerate case where name is null string
472 * if .. and crossing mount points and on mounted filesys, find parent
473 * call VOP_LOOKUP routine for next component name
474 * directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set
475 * component vnode returned in ni_vp (if it exists), locked.
476 * if result vnode is mounted on and crossing mount points,
477 * find mounted on vnode
478 * if more components of name, do next level at dirloop
479 * return the answer in ni_vp, locked if LOCKLEAF set
480 * if LOCKPARENT set, return locked parent in ni_dvp
481 * if WANTPARENT set, return unlocked parent in ni_dvp
482 */
483 int
484 lookup(struct nameidata *ndp)
485 {
486 char *cp; /* pointer into pathname argument */
487 struct vnode *dp = 0; /* the directory we are searching */
488 struct vnode *tdp; /* saved dp */
489 struct mount *mp; /* mount table entry */
490 struct prison *pr;
491 int docache; /* == 0 do not cache last component */
492 int wantparent; /* 1 => wantparent or lockparent flag */
493 int rdonly; /* lookup read-only flag bit */
494 int error = 0;
495 int dpunlocked = 0; /* dp has already been unlocked */
496 struct componentname *cnp = &ndp->ni_cnd;
497 int vfslocked; /* VFS Giant state for child */
498 int dvfslocked; /* VFS Giant state for parent */
499 int tvfslocked;
500 int lkflags_save;
501
502 /*
503 * Setup: break out flag bits into variables.
504 */
505 dvfslocked = (ndp->ni_cnd.cn_flags & GIANTHELD) != 0;
506 vfslocked = 0;
507 ndp->ni_cnd.cn_flags &= ~GIANTHELD;
508 wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT);
509 KASSERT(cnp->cn_nameiop == LOOKUP || wantparent,
510 ("CREATE, DELETE, RENAME require LOCKPARENT or WANTPARENT."));
511 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE;
512 if (cnp->cn_nameiop == DELETE ||
513 (wantparent && cnp->cn_nameiop != CREATE &&
514 cnp->cn_nameiop != LOOKUP))
515 docache = 0;
516 rdonly = cnp->cn_flags & RDONLY;
517 cnp->cn_flags &= ~ISSYMLINK;
518 ndp->ni_dvp = NULL;
519 /*
520 * We use shared locks until we hit the parent of the last cn then
521 * we adjust based on the requesting flags.
522 */
523 if (lookup_shared)
524 cnp->cn_lkflags = LK_SHARED;
525 else
526 cnp->cn_lkflags = LK_EXCLUSIVE;
527 dp = ndp->ni_startdir;
528 ndp->ni_startdir = NULLVP;
529 vn_lock(dp,
530 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | LK_RETRY));
531
532 dirloop:
533 /*
534 * Search a new directory.
535 *
536 * The last component of the filename is left accessible via
537 * cnp->cn_nameptr for callers that need the name. Callers needing
538 * the name set the SAVENAME flag. When done, they assume
539 * responsibility for freeing the pathname buffer.
540 */
541 cnp->cn_consume = 0;
542 for (cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++)
543 continue;
544 cnp->cn_namelen = cp - cnp->cn_nameptr;
545 if (cnp->cn_namelen > NAME_MAX) {
546 error = ENAMETOOLONG;
547 goto bad;
548 }
549 #ifdef NAMEI_DIAGNOSTIC
550 { char c = *cp;
551 *cp = '\0';
552 printf("{%s}: ", cnp->cn_nameptr);
553 *cp = c; }
554 #endif
555 ndp->ni_pathlen -= cnp->cn_namelen;
556 ndp->ni_next = cp;
557
558 /*
559 * Replace multiple slashes by a single slash and trailing slashes
560 * by a null. This must be done before VOP_LOOKUP() because some
561 * fs's don't know about trailing slashes. Remember if there were
562 * trailing slashes to handle symlinks, existing non-directories
563 * and non-existing files that won't be directories specially later.
564 */
565 while (*cp == '/' && (cp[1] == '/' || cp[1] == '\0')) {
566 cp++;
567 ndp->ni_pathlen--;
568 if (*cp == '\0') {
569 *ndp->ni_next = '\0';
570 cnp->cn_flags |= TRAILINGSLASH;
571 }
572 }
573 ndp->ni_next = cp;
574
575 cnp->cn_flags |= MAKEENTRY;
576 if (*cp == '\0' && docache == 0)
577 cnp->cn_flags &= ~MAKEENTRY;
578 if (cnp->cn_namelen == 2 &&
579 cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.')
580 cnp->cn_flags |= ISDOTDOT;
581 else
582 cnp->cn_flags &= ~ISDOTDOT;
583 if (*ndp->ni_next == 0)
584 cnp->cn_flags |= ISLASTCN;
585 else
586 cnp->cn_flags &= ~ISLASTCN;
587
588 if ((cnp->cn_flags & ISLASTCN) != 0 &&
589 cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.' &&
590 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
591 error = EINVAL;
592 goto bad;
593 }
594
595 /*
596 * Check for degenerate name (e.g. / or "")
597 * which is a way of talking about a directory,
598 * e.g. like "/." or ".".
599 */
600 if (cnp->cn_nameptr[0] == '\0') {
601 if (dp->v_type != VDIR) {
602 error = ENOTDIR;
603 goto bad;
604 }
605 if (cnp->cn_nameiop != LOOKUP) {
606 error = EISDIR;
607 goto bad;
608 }
609 if (wantparent) {
610 ndp->ni_dvp = dp;
611 VREF(dp);
612 }
613 ndp->ni_vp = dp;
614
615 if (cnp->cn_flags & AUDITVNODE1)
616 AUDIT_ARG_VNODE1(dp);
617 else if (cnp->cn_flags & AUDITVNODE2)
618 AUDIT_ARG_VNODE2(dp);
619
620 if (!(cnp->cn_flags & (LOCKPARENT | LOCKLEAF)))
621 VOP_UNLOCK(dp, 0);
622 /* XXX This should probably move to the top of function. */
623 if (cnp->cn_flags & SAVESTART)
624 panic("lookup: SAVESTART");
625 goto success;
626 }
627
628 /*
629 * Handle "..": five special cases.
630 * 0. If doing a capability lookup, return ENOTCAPABLE (this is a
631 * fairly conservative design choice, but it's the only one that we
632 * are satisfied guarantees the property we're looking for).
633 * 1. Return an error if this is the last component of
634 * the name and the operation is DELETE or RENAME.
635 * 2. If at root directory (e.g. after chroot)
636 * or at absolute root directory
637 * then ignore it so can't get out.
638 * 3. If this vnode is the root of a mounted
639 * filesystem, then replace it with the
640 * vnode which was mounted on so we take the
641 * .. in the other filesystem.
642 * 4. If the vnode is the top directory of
643 * the jail or chroot, don't let them out.
644 */
645 if (cnp->cn_flags & ISDOTDOT) {
646 if (ndp->ni_strictrelative != 0) {
647 error = ENOTCAPABLE;
648 goto bad;
649 }
650 if ((cnp->cn_flags & ISLASTCN) != 0 &&
651 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
652 error = EINVAL;
653 goto bad;
654 }
655 for (;;) {
656 for (pr = cnp->cn_cred->cr_prison; pr != NULL;
657 pr = pr->pr_parent)
658 if (dp == pr->pr_root)
659 break;
660 if (dp == ndp->ni_rootdir ||
661 dp == ndp->ni_topdir ||
662 dp == rootvnode ||
663 pr != NULL ||
664 ((dp->v_vflag & VV_ROOT) != 0 &&
665 (cnp->cn_flags & NOCROSSMOUNT) != 0)) {
666 ndp->ni_dvp = dp;
667 ndp->ni_vp = dp;
668 vfslocked = VFS_LOCK_GIANT(dp->v_mount);
669 VREF(dp);
670 goto nextname;
671 }
672 if ((dp->v_vflag & VV_ROOT) == 0)
673 break;
674 if (dp->v_iflag & VI_DOOMED) { /* forced unmount */
675 error = ENOENT;
676 goto bad;
677 }
678 tdp = dp;
679 dp = dp->v_mount->mnt_vnodecovered;
680 tvfslocked = dvfslocked;
681 dvfslocked = VFS_LOCK_GIANT(dp->v_mount);
682 VREF(dp);
683 vput(tdp);
684 VFS_UNLOCK_GIANT(tvfslocked);
685 vn_lock(dp,
686 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags |
687 LK_RETRY));
688 }
689 }
690
691 /*
692 * We now have a segment name to search for, and a directory to search.
693 */
694 unionlookup:
695 #ifdef MAC
696 if ((cnp->cn_flags & NOMACCHECK) == 0) {
697 error = mac_vnode_check_lookup(cnp->cn_thread->td_ucred, dp,
698 cnp);
699 if (error)
700 goto bad;
701 }
702 #endif
703 ndp->ni_dvp = dp;
704 ndp->ni_vp = NULL;
705 ASSERT_VOP_LOCKED(dp, "lookup");
706 VNASSERT(vfslocked == 0, dp, ("lookup: vfslocked %d", vfslocked));
707 /*
708 * If we have a shared lock we may need to upgrade the lock for the
709 * last operation.
710 */
711 if (dp != vp_crossmp &&
712 VOP_ISLOCKED(dp) == LK_SHARED &&
713 (cnp->cn_flags & ISLASTCN) && (cnp->cn_flags & LOCKPARENT))
714 vn_lock(dp, LK_UPGRADE|LK_RETRY);
715 /*
716 * If we're looking up the last component and we need an exclusive
717 * lock, adjust our lkflags.
718 */
719 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags))
720 cnp->cn_lkflags = LK_EXCLUSIVE;
721 #ifdef NAMEI_DIAGNOSTIC
722 vprint("lookup in", dp);
723 #endif
724 lkflags_save = cnp->cn_lkflags;
725 cnp->cn_lkflags = compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags);
726 if ((error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp)) != 0) {
727 cnp->cn_lkflags = lkflags_save;
728 KASSERT(ndp->ni_vp == NULL, ("leaf should be empty"));
729 #ifdef NAMEI_DIAGNOSTIC
730 printf("not found\n");
731 #endif
732 if ((error == ENOENT) &&
733 (dp->v_vflag & VV_ROOT) && (dp->v_mount != NULL) &&
734 (dp->v_mount->mnt_flag & MNT_UNION)) {
735 tdp = dp;
736 dp = dp->v_mount->mnt_vnodecovered;
737 tvfslocked = dvfslocked;
738 dvfslocked = VFS_LOCK_GIANT(dp->v_mount);
739 VREF(dp);
740 vput(tdp);
741 VFS_UNLOCK_GIANT(tvfslocked);
742 vn_lock(dp,
743 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags |
744 LK_RETRY));
745 goto unionlookup;
746 }
747
748 if (error != EJUSTRETURN)
749 goto bad;
750 /*
751 * At this point, we know we're at the end of the
752 * pathname. If creating / renaming, we can consider
753 * allowing the file or directory to be created / renamed,
754 * provided we're not on a read-only filesystem.
755 */
756 if (rdonly) {
757 error = EROFS;
758 goto bad;
759 }
760 /* trailing slash only allowed for directories */
761 if ((cnp->cn_flags & TRAILINGSLASH) &&
762 !(cnp->cn_flags & WILLBEDIR)) {
763 error = ENOENT;
764 goto bad;
765 }
766 if ((cnp->cn_flags & LOCKPARENT) == 0)
767 VOP_UNLOCK(dp, 0);
768 /*
769 * We return with ni_vp NULL to indicate that the entry
770 * doesn't currently exist, leaving a pointer to the
771 * (possibly locked) directory vnode in ndp->ni_dvp.
772 */
773 if (cnp->cn_flags & SAVESTART) {
774 ndp->ni_startdir = ndp->ni_dvp;
775 VREF(ndp->ni_startdir);
776 }
777 goto success;
778 } else
779 cnp->cn_lkflags = lkflags_save;
780 #ifdef NAMEI_DIAGNOSTIC
781 printf("found\n");
782 #endif
783 /*
784 * Take into account any additional components consumed by
785 * the underlying filesystem.
786 */
787 if (cnp->cn_consume > 0) {
788 cnp->cn_nameptr += cnp->cn_consume;
789 ndp->ni_next += cnp->cn_consume;
790 ndp->ni_pathlen -= cnp->cn_consume;
791 cnp->cn_consume = 0;
792 }
793
794 dp = ndp->ni_vp;
795 vfslocked = VFS_LOCK_GIANT(dp->v_mount);
796
797 /*
798 * Check to see if the vnode has been mounted on;
799 * if so find the root of the mounted filesystem.
800 */
801 while (dp->v_type == VDIR && (mp = dp->v_mountedhere) &&
802 (cnp->cn_flags & NOCROSSMOUNT) == 0) {
803 if (vfs_busy(mp, 0))
804 continue;
805 vput(dp);
806 VFS_UNLOCK_GIANT(vfslocked);
807 vfslocked = VFS_LOCK_GIANT(mp);
808 if (dp != ndp->ni_dvp)
809 vput(ndp->ni_dvp);
810 else
811 vrele(ndp->ni_dvp);
812 VFS_UNLOCK_GIANT(dvfslocked);
813 dvfslocked = 0;
814 vref(vp_crossmp);
815 ndp->ni_dvp = vp_crossmp;
816 error = VFS_ROOT(mp, compute_cn_lkflags(mp, cnp->cn_lkflags),
817 &tdp);
818 vfs_unbusy(mp);
819 if (vn_lock(vp_crossmp, LK_SHARED | LK_NOWAIT))
820 panic("vp_crossmp exclusively locked or reclaimed");
821 if (error) {
822 dpunlocked = 1;
823 goto bad2;
824 }
825 ndp->ni_vp = dp = tdp;
826 }
827
828 /*
829 * Check for symbolic link
830 */
831 if ((dp->v_type == VLNK) &&
832 ((cnp->cn_flags & FOLLOW) || (cnp->cn_flags & TRAILINGSLASH) ||
833 *ndp->ni_next == '/')) {
834 cnp->cn_flags |= ISSYMLINK;
835 if (dp->v_iflag & VI_DOOMED) {
836 /*
837 * We can't know whether the directory was mounted with
838 * NOSYMFOLLOW, so we can't follow safely.
839 */
840 error = ENOENT;
841 goto bad2;
842 }
843 if (dp->v_mount->mnt_flag & MNT_NOSYMFOLLOW) {
844 error = EACCES;
845 goto bad2;
846 }
847 /*
848 * Symlink code always expects an unlocked dvp.
849 */
850 if (ndp->ni_dvp != ndp->ni_vp)
851 VOP_UNLOCK(ndp->ni_dvp, 0);
852 goto success;
853 }
854
855 nextname:
856 /*
857 * Not a symbolic link that we will follow. Continue with the
858 * next component if there is any; otherwise, we're done.
859 */
860 KASSERT((cnp->cn_flags & ISLASTCN) || *ndp->ni_next == '/',
861 ("lookup: invalid path state."));
862 if (*ndp->ni_next == '/') {
863 cnp->cn_nameptr = ndp->ni_next;
864 while (*cnp->cn_nameptr == '/') {
865 cnp->cn_nameptr++;
866 ndp->ni_pathlen--;
867 }
868 if (ndp->ni_dvp != dp)
869 vput(ndp->ni_dvp);
870 else
871 vrele(ndp->ni_dvp);
872 VFS_UNLOCK_GIANT(dvfslocked);
873 dvfslocked = vfslocked; /* dp becomes dvp in dirloop */
874 vfslocked = 0;
875 goto dirloop;
876 }
877 /*
878 * If we're processing a path with a trailing slash,
879 * check that the end result is a directory.
880 */
881 if ((cnp->cn_flags & TRAILINGSLASH) && dp->v_type != VDIR) {
882 error = ENOTDIR;
883 goto bad2;
884 }
885 /*
886 * Disallow directory write attempts on read-only filesystems.
887 */
888 if (rdonly &&
889 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
890 error = EROFS;
891 goto bad2;
892 }
893 if (cnp->cn_flags & SAVESTART) {
894 ndp->ni_startdir = ndp->ni_dvp;
895 VREF(ndp->ni_startdir);
896 }
897 if (!wantparent) {
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
907 if (cnp->cn_flags & AUDITVNODE1)
908 AUDIT_ARG_VNODE1(dp);
909 else if (cnp->cn_flags & AUDITVNODE2)
910 AUDIT_ARG_VNODE2(dp);
911
912 if ((cnp->cn_flags & LOCKLEAF) == 0)
913 VOP_UNLOCK(dp, 0);
914 success:
915 /*
916 * Because of lookup_shared we may have the vnode shared locked, but
917 * the caller may want it to be exclusively locked.
918 */
919 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags) &&
920 VOP_ISLOCKED(dp) != LK_EXCLUSIVE) {
921 vn_lock(dp, LK_UPGRADE | LK_RETRY);
922 if (dp->v_iflag & VI_DOOMED) {
923 error = ENOENT;
924 goto bad2;
925 }
926 }
927 if (vfslocked && dvfslocked)
928 VFS_UNLOCK_GIANT(dvfslocked); /* Only need one */
929 if (vfslocked || dvfslocked)
930 ndp->ni_cnd.cn_flags |= GIANTHELD;
931 return (0);
932
933 bad2:
934 if (dp != ndp->ni_dvp)
935 vput(ndp->ni_dvp);
936 else
937 vrele(ndp->ni_dvp);
938 bad:
939 if (!dpunlocked)
940 vput(dp);
941 VFS_UNLOCK_GIANT(vfslocked);
942 VFS_UNLOCK_GIANT(dvfslocked);
943 ndp->ni_cnd.cn_flags &= ~GIANTHELD;
944 ndp->ni_vp = NULL;
945 return (error);
946 }
947
948 /*
949 * relookup - lookup a path name component
950 * Used by lookup to re-acquire things.
951 */
952 int
953 relookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp)
954 {
955 struct vnode *dp = 0; /* the directory we are searching */
956 int wantparent; /* 1 => wantparent or lockparent flag */
957 int rdonly; /* lookup read-only flag bit */
958 int error = 0;
959
960 KASSERT(cnp->cn_flags & ISLASTCN,
961 ("relookup: Not given last component."));
962 /*
963 * Setup: break out flag bits into variables.
964 */
965 wantparent = cnp->cn_flags & (LOCKPARENT|WANTPARENT);
966 KASSERT(wantparent, ("relookup: parent not wanted."));
967 rdonly = cnp->cn_flags & RDONLY;
968 cnp->cn_flags &= ~ISSYMLINK;
969 dp = dvp;
970 cnp->cn_lkflags = LK_EXCLUSIVE;
971 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY);
972
973 /*
974 * Search a new directory.
975 *
976 * The last component of the filename is left accessible via
977 * cnp->cn_nameptr for callers that need the name. Callers needing
978 * the name set the SAVENAME flag. When done, they assume
979 * responsibility for freeing the pathname buffer.
980 */
981 #ifdef NAMEI_DIAGNOSTIC
982 printf("{%s}: ", cnp->cn_nameptr);
983 #endif
984
985 /*
986 * Check for "" which represents the root directory after slash
987 * removal.
988 */
989 if (cnp->cn_nameptr[0] == '\0') {
990 /*
991 * Support only LOOKUP for "/" because lookup()
992 * can't succeed for CREATE, DELETE and RENAME.
993 */
994 KASSERT(cnp->cn_nameiop == LOOKUP, ("nameiop must be LOOKUP"));
995 KASSERT(dp->v_type == VDIR, ("dp is not a directory"));
996
997 if (!(cnp->cn_flags & LOCKLEAF))
998 VOP_UNLOCK(dp, 0);
999 *vpp = dp;
1000 /* XXX This should probably move to the top of function. */
1001 if (cnp->cn_flags & SAVESTART)
1002 panic("lookup: SAVESTART");
1003 return (0);
1004 }
1005
1006 if (cnp->cn_flags & ISDOTDOT)
1007 panic ("relookup: lookup on dot-dot");
1008
1009 /*
1010 * We now have a segment name to search for, and a directory to search.
1011 */
1012 #ifdef NAMEI_DIAGNOSTIC
1013 vprint("search in:", dp);
1014 #endif
1015 if ((error = VOP_LOOKUP(dp, vpp, cnp)) != 0) {
1016 KASSERT(*vpp == NULL, ("leaf should be empty"));
1017 if (error != EJUSTRETURN)
1018 goto bad;
1019 /*
1020 * If creating and at end of pathname, then can consider
1021 * allowing file to be created.
1022 */
1023 if (rdonly) {
1024 error = EROFS;
1025 goto bad;
1026 }
1027 /* ASSERT(dvp == ndp->ni_startdir) */
1028 if (cnp->cn_flags & SAVESTART)
1029 VREF(dvp);
1030 if ((cnp->cn_flags & LOCKPARENT) == 0)
1031 VOP_UNLOCK(dp, 0);
1032 /*
1033 * We return with ni_vp NULL to indicate that the entry
1034 * doesn't currently exist, leaving a pointer to the
1035 * (possibly locked) directory vnode in ndp->ni_dvp.
1036 */
1037 return (0);
1038 }
1039
1040 dp = *vpp;
1041
1042 /*
1043 * Disallow directory write attempts on read-only filesystems.
1044 */
1045 if (rdonly &&
1046 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
1047 if (dvp == dp)
1048 vrele(dvp);
1049 else
1050 vput(dvp);
1051 error = EROFS;
1052 goto bad;
1053 }
1054 /*
1055 * Set the parent lock/ref state to the requested state.
1056 */
1057 if ((cnp->cn_flags & LOCKPARENT) == 0 && dvp != dp) {
1058 if (wantparent)
1059 VOP_UNLOCK(dvp, 0);
1060 else
1061 vput(dvp);
1062 } else if (!wantparent)
1063 vrele(dvp);
1064 /*
1065 * Check for symbolic link
1066 */
1067 KASSERT(dp->v_type != VLNK || !(cnp->cn_flags & FOLLOW),
1068 ("relookup: symlink found.\n"));
1069
1070 /* ASSERT(dvp == ndp->ni_startdir) */
1071 if (cnp->cn_flags & SAVESTART)
1072 VREF(dvp);
1073
1074 if ((cnp->cn_flags & LOCKLEAF) == 0)
1075 VOP_UNLOCK(dp, 0);
1076 return (0);
1077 bad:
1078 vput(dp);
1079 *vpp = NULL;
1080 return (error);
1081 }
1082
1083 /*
1084 * Free data allocated by namei(); see namei(9) for details.
1085 */
1086 void
1087 NDFREE(struct nameidata *ndp, const u_int flags)
1088 {
1089 int unlock_dvp;
1090 int unlock_vp;
1091
1092 unlock_dvp = 0;
1093 unlock_vp = 0;
1094
1095 if (!(flags & NDF_NO_FREE_PNBUF) &&
1096 (ndp->ni_cnd.cn_flags & HASBUF)) {
1097 uma_zfree(namei_zone, ndp->ni_cnd.cn_pnbuf);
1098 ndp->ni_cnd.cn_flags &= ~HASBUF;
1099 }
1100 if (!(flags & NDF_NO_VP_UNLOCK) &&
1101 (ndp->ni_cnd.cn_flags & LOCKLEAF) && ndp->ni_vp)
1102 unlock_vp = 1;
1103 if (!(flags & NDF_NO_VP_RELE) && ndp->ni_vp) {
1104 if (unlock_vp) {
1105 vput(ndp->ni_vp);
1106 unlock_vp = 0;
1107 } else
1108 vrele(ndp->ni_vp);
1109 ndp->ni_vp = NULL;
1110 }
1111 if (unlock_vp)
1112 VOP_UNLOCK(ndp->ni_vp, 0);
1113 if (!(flags & NDF_NO_DVP_UNLOCK) &&
1114 (ndp->ni_cnd.cn_flags & LOCKPARENT) &&
1115 ndp->ni_dvp != ndp->ni_vp)
1116 unlock_dvp = 1;
1117 if (!(flags & NDF_NO_DVP_RELE) &&
1118 (ndp->ni_cnd.cn_flags & (LOCKPARENT|WANTPARENT))) {
1119 if (unlock_dvp) {
1120 vput(ndp->ni_dvp);
1121 unlock_dvp = 0;
1122 } else
1123 vrele(ndp->ni_dvp);
1124 ndp->ni_dvp = NULL;
1125 }
1126 if (unlock_dvp)
1127 VOP_UNLOCK(ndp->ni_dvp, 0);
1128 if (!(flags & NDF_NO_STARTDIR_RELE) &&
1129 (ndp->ni_cnd.cn_flags & SAVESTART)) {
1130 vrele(ndp->ni_startdir);
1131 ndp->ni_startdir = NULL;
1132 }
1133 }
1134
1135 /*
1136 * Determine if there is a suitable alternate filename under the specified
1137 * prefix for the specified path. If the create flag is set, then the
1138 * alternate prefix will be used so long as the parent directory exists.
1139 * This is used by the various compatiblity ABIs so that Linux binaries prefer
1140 * files under /compat/linux for example. The chosen path (whether under
1141 * the prefix or under /) is returned in a kernel malloc'd buffer pointed
1142 * to by pathbuf. The caller is responsible for free'ing the buffer from
1143 * the M_TEMP bucket if one is returned.
1144 */
1145 int
1146 kern_alternate_path(struct thread *td, const char *prefix, const char *path,
1147 enum uio_seg pathseg, char **pathbuf, int create, int dirfd)
1148 {
1149 struct nameidata nd, ndroot;
1150 char *ptr, *buf, *cp;
1151 size_t len, sz;
1152 int error;
1153
1154 buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
1155 *pathbuf = buf;
1156
1157 /* Copy the prefix into the new pathname as a starting point. */
1158 len = strlcpy(buf, prefix, MAXPATHLEN);
1159 if (len >= MAXPATHLEN) {
1160 *pathbuf = NULL;
1161 free(buf, M_TEMP);
1162 return (EINVAL);
1163 }
1164 sz = MAXPATHLEN - len;
1165 ptr = buf + len;
1166
1167 /* Append the filename to the prefix. */
1168 if (pathseg == UIO_SYSSPACE)
1169 error = copystr(path, ptr, sz, &len);
1170 else
1171 error = copyinstr(path, ptr, sz, &len);
1172
1173 if (error) {
1174 *pathbuf = NULL;
1175 free(buf, M_TEMP);
1176 return (error);
1177 }
1178
1179 /* Only use a prefix with absolute pathnames. */
1180 if (*ptr != '/') {
1181 error = EINVAL;
1182 goto keeporig;
1183 }
1184
1185 if (dirfd != AT_FDCWD) {
1186 /*
1187 * We want the original because the "prefix" is
1188 * included in the already opened dirfd.
1189 */
1190 bcopy(ptr, buf, len);
1191 return (0);
1192 }
1193
1194 /*
1195 * We know that there is a / somewhere in this pathname.
1196 * Search backwards for it, to find the file's parent dir
1197 * to see if it exists in the alternate tree. If it does,
1198 * and we want to create a file (cflag is set). We don't
1199 * need to worry about the root comparison in this case.
1200 */
1201
1202 if (create) {
1203 for (cp = &ptr[len] - 1; *cp != '/'; cp--);
1204 *cp = '\0';
1205
1206 NDINIT(&nd, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, buf, td);
1207 error = namei(&nd);
1208 *cp = '/';
1209 if (error != 0)
1210 goto keeporig;
1211 } else {
1212 NDINIT(&nd, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, buf, td);
1213
1214 error = namei(&nd);
1215 if (error != 0)
1216 goto keeporig;
1217
1218 /*
1219 * We now compare the vnode of the prefix to the one
1220 * vnode asked. If they resolve to be the same, then we
1221 * ignore the match so that the real root gets used.
1222 * This avoids the problem of traversing "../.." to find the
1223 * root directory and never finding it, because "/" resolves
1224 * to the emulation root directory. This is expensive :-(
1225 */
1226 NDINIT(&ndroot, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, prefix,
1227 td);
1228
1229 /* We shouldn't ever get an error from this namei(). */
1230 error = namei(&ndroot);
1231 if (error == 0) {
1232 if (nd.ni_vp == ndroot.ni_vp)
1233 error = ENOENT;
1234
1235 NDFREE(&ndroot, NDF_ONLY_PNBUF);
1236 vrele(ndroot.ni_vp);
1237 VFS_UNLOCK_GIANT(NDHASGIANT(&ndroot));
1238 }
1239 }
1240
1241 NDFREE(&nd, NDF_ONLY_PNBUF);
1242 vrele(nd.ni_vp);
1243 VFS_UNLOCK_GIANT(NDHASGIANT(&nd));
1244
1245 keeporig:
1246 /* If there was an error, use the original path name. */
1247 if (error)
1248 bcopy(ptr, buf, len);
1249 return (error);
1250 }
Cache object: 8e5c01921d9d223c5f3ec6102c35a95f
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