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.
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
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.
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
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29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * @(#)vfs_lookup.c 8.4 (Berkeley) 2/16/94
37 #include <sys/cdefs.h>
38 __FBSDID("$FreeBSD$");
40 #include "opt_capsicum.h"
41 #include "opt_kdtrace.h"
42 #include "opt_ktrace.h"
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>
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>
58 #include <sys/syscallsubr.h>
59 #include <sys/sysctl.h>
61 #include <sys/ktrace.h>
64 #include <security/audit/audit.h>
65 #include <security/mac/mac_framework.h>
69 #define NAMEI_DIAGNOSTIC 1
70 #undef NAMEI_DIAGNOSTIC
72 SDT_PROVIDER_DECLARE(vfs);
73 SDT_PROBE_DEFINE3(vfs, namei, lookup, entry, entry, "struct vnode *", "char *",
75 SDT_PROBE_DEFINE2(vfs, namei, lookup, return, return, "int", "struct vnode *");
78 * Allocation zone for namei
80 uma_zone_t namei_zone;
82 * Placeholder vnode for mp traversal
84 static struct vnode *vp_crossmp;
87 nameiinit(void *dummy __unused)
90 namei_zone = uma_zcreate("NAMEI", MAXPATHLEN, NULL, NULL, NULL, NULL,
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);
97 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nameiinit, NULL);
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);
105 * Convert a pathname into a pointer to a locked vnode.
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.
112 * The segflg defines whether the name is to be copied from user
113 * space or kernel space.
115 * Overall outline of namei:
118 * get starting directory
119 * while (!done && !error) {
120 * call lookup to search path.
121 * if symbolic link, massage name in buffer and continue
125 namei(struct nameidata *ndp)
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 */
133 struct componentname *cnp = &ndp->ni_cnd;
134 struct thread *td = cnp->cn_thread;
135 struct proc *p = td->td_proc;
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"));
147 cnp->cn_flags &= ~LOCKSHARED;
150 /* We will set this ourselves if we need it. */
151 cnp->cn_flags &= ~TRAILINGSLASH;
154 * Get a buffer for the name to be translated, and copy the
155 * name into the buffer.
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);
163 error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf,
164 MAXPATHLEN, (size_t *)&ndp->ni_pathlen);
168 * If we are auditing the kernel pathname, save the user
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);
178 * Don't allow empty pathnames.
180 if (!error && *cnp->cn_pnbuf == '\0')
183 #ifdef CAPABILITY_MODE
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.
189 if (IN_CAPABILITY_MODE(td)) {
190 ndp->ni_strictrelative = 1;
191 if (ndp->ni_dirfd == AT_FDCWD) {
193 if (KTRPOINT(td, KTR_CAPFAIL))
194 ktrcapfail(CAPFAIL_LOOKUP, 0, 0);
201 uma_zfree(namei_zone, cnp->cn_pnbuf);
203 cnp->cn_pnbuf = NULL;
204 cnp->cn_nameptr = NULL;
211 if (KTRPOINT(td, KTR_NAMEI)) {
212 KASSERT(cnp->cn_thread == curthread,
213 ("namei not using curthread"));
214 ktrnamei(cnp->cn_pnbuf);
218 * Get starting point for the translation.
221 ndp->ni_rootdir = fdp->fd_rdir;
222 ndp->ni_topdir = fdp->fd_jdir;
225 if (cnp->cn_pnbuf[0] != '/') {
226 if (ndp->ni_startdir != NULL) {
227 dp = ndp->ni_startdir;
229 } else if (ndp->ni_dirfd != AT_FDCWD) {
230 if (cnp->cn_flags & AUDITVNODE1)
231 AUDIT_ARG_ATFD1(ndp->ni_dirfd);
232 if (cnp->cn_flags & AUDITVNODE2)
233 AUDIT_ARG_ATFD2(ndp->ni_dirfd);
234 error = fgetvp_rights(td, ndp->ni_dirfd,
235 ndp->ni_rightsneeded | CAP_LOOKUP,
236 &(ndp->ni_baserights), &dp);
239 * Lookups relative to a capability must also be
242 * Note that a capability with rights CAP_MASK_VALID
243 * is treated exactly like a regular file descriptor.
245 if (ndp->ni_baserights != CAP_MASK_VALID)
246 ndp->ni_strictrelative = 1;
249 if (error != 0 || dp != NULL) {
250 FILEDESC_SUNLOCK(fdp);
251 if (error == 0 && dp->v_type != VDIR) {
252 vfslocked = VFS_LOCK_GIANT(dp->v_mount);
254 VFS_UNLOCK_GIANT(vfslocked);
259 uma_zfree(namei_zone, cnp->cn_pnbuf);
261 cnp->cn_pnbuf = NULL;
262 cnp->cn_nameptr = NULL;
270 FILEDESC_SUNLOCK(fdp);
271 if (ndp->ni_startdir != NULL) {
272 vfslocked = VFS_LOCK_GIANT(ndp->ni_startdir->v_mount);
273 vrele(ndp->ni_startdir);
274 VFS_UNLOCK_GIANT(vfslocked);
277 SDT_PROBE(vfs, namei, lookup, entry, dp, cnp->cn_pnbuf,
278 cnp->cn_flags, 0, 0);
279 vfslocked = VFS_LOCK_GIANT(dp->v_mount);
282 * Check if root directory should replace current directory.
283 * Done at start of translation and after symbolic link.
285 cnp->cn_nameptr = cnp->cn_pnbuf;
286 if (*(cnp->cn_nameptr) == '/') {
288 VFS_UNLOCK_GIANT(vfslocked);
289 if (ndp->ni_strictrelative != 0) {
291 if (KTRPOINT(curthread, KTR_CAPFAIL))
292 ktrcapfail(CAPFAIL_LOOKUP, 0, 0);
294 return (ENOTCAPABLE);
296 while (*(cnp->cn_nameptr) == '/') {
300 dp = ndp->ni_rootdir;
301 vfslocked = VFS_LOCK_GIANT(dp->v_mount);
305 ndp->ni_cnd.cn_flags |= GIANTHELD;
306 ndp->ni_startdir = dp;
309 uma_zfree(namei_zone, cnp->cn_pnbuf);
311 cnp->cn_pnbuf = NULL;
312 cnp->cn_nameptr = NULL;
314 SDT_PROBE(vfs, namei, lookup, return, error, NULL, 0,
318 vfslocked = (ndp->ni_cnd.cn_flags & GIANTHELD) != 0;
319 ndp->ni_cnd.cn_flags &= ~GIANTHELD;
321 * If not a symbolic link, we're done.
323 if ((cnp->cn_flags & ISSYMLINK) == 0) {
324 if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) {
325 uma_zfree(namei_zone, cnp->cn_pnbuf);
327 cnp->cn_pnbuf = NULL;
328 cnp->cn_nameptr = NULL;
331 cnp->cn_flags |= HASBUF;
333 if ((cnp->cn_flags & MPSAFE) == 0) {
334 VFS_UNLOCK_GIANT(vfslocked);
335 } else if (vfslocked)
336 ndp->ni_cnd.cn_flags |= GIANTHELD;
337 SDT_PROBE(vfs, namei, lookup, return, 0, ndp->ni_vp,
341 if (ndp->ni_loopcnt++ >= MAXSYMLINKS) {
346 if ((cnp->cn_flags & NOMACCHECK) == 0) {
347 error = mac_vnode_check_readlink(td->td_ucred,
353 if (ndp->ni_pathlen > 1)
354 cp = uma_zalloc(namei_zone, M_WAITOK);
358 aiov.iov_len = MAXPATHLEN;
359 auio.uio_iov = &aiov;
362 auio.uio_rw = UIO_READ;
363 auio.uio_segflg = UIO_SYSSPACE;
364 auio.uio_td = (struct thread *)0;
365 auio.uio_resid = MAXPATHLEN;
366 error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred);
368 if (ndp->ni_pathlen > 1)
369 uma_zfree(namei_zone, cp);
372 linklen = MAXPATHLEN - auio.uio_resid;
374 if (ndp->ni_pathlen > 1)
375 uma_zfree(namei_zone, cp);
379 if (linklen + ndp->ni_pathlen >= MAXPATHLEN) {
380 if (ndp->ni_pathlen > 1)
381 uma_zfree(namei_zone, cp);
382 error = ENAMETOOLONG;
385 if (ndp->ni_pathlen > 1) {
386 bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen);
387 uma_zfree(namei_zone, cnp->cn_pnbuf);
390 cnp->cn_pnbuf[linklen] = '\0';
391 ndp->ni_pathlen += linklen;
395 uma_zfree(namei_zone, cnp->cn_pnbuf);
397 cnp->cn_pnbuf = NULL;
398 cnp->cn_nameptr = NULL;
403 VFS_UNLOCK_GIANT(vfslocked);
404 SDT_PROBE(vfs, namei, lookup, return, error, NULL, 0, 0, 0);
409 compute_cn_lkflags(struct mount *mp, int lkflags)
413 ((lkflags & LK_SHARED) && !(mp->mnt_kern_flag & MNTK_LOOKUP_SHARED))) {
414 lkflags &= ~LK_SHARED;
415 lkflags |= LK_EXCLUSIVE;
421 needs_exclusive_leaf(struct mount *mp, int flags)
425 * Intermediate nodes can use shared locks, we only need to
426 * force an exclusive lock for leaf nodes.
428 if ((flags & (ISLASTCN | LOCKLEAF)) != (ISLASTCN | LOCKLEAF))
431 /* Always use exclusive locks if LOCKSHARED isn't set. */
432 if (!(flags & LOCKSHARED))
436 * For lookups during open(), if the mount point supports
437 * extended shared operations, then use a shared lock for the
438 * leaf node, otherwise use an exclusive lock.
440 if (flags & ISOPEN) {
442 (mp->mnt_kern_flag & MNTK_EXTENDED_SHARED))
449 * Lookup requests outside of open() that specify LOCKSHARED
450 * only need a shared lock on the leaf vnode.
457 * This is a very central and rather complicated routine.
459 * The pathname is pointed to by ni_ptr and is of length ni_pathlen.
460 * The starting directory is taken from ni_startdir. The pathname is
461 * descended until done, or a symbolic link is encountered. The variable
462 * ni_more is clear if the path is completed; it is set to one if a
463 * symbolic link needing interpretation is encountered.
465 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on
466 * whether the name is to be looked up, created, renamed, or deleted.
467 * When CREATE, RENAME, or DELETE is specified, information usable in
468 * creating, renaming, or deleting a directory entry may be calculated.
469 * If flag has LOCKPARENT or'ed into it, the parent directory is returned
470 * locked. If flag has WANTPARENT or'ed into it, the parent directory is
471 * returned unlocked. Otherwise the parent directory is not returned. If
472 * the target of the pathname exists and LOCKLEAF is or'ed into the flag
473 * the target is returned locked, otherwise it is returned unlocked.
474 * When creating or renaming and LOCKPARENT is specified, the target may not
475 * be ".". When deleting and LOCKPARENT is specified, the target may be ".".
477 * Overall outline of lookup:
480 * identify next component of name at ndp->ni_ptr
481 * handle degenerate case where name is null string
482 * if .. and crossing mount points and on mounted filesys, find parent
483 * call VOP_LOOKUP routine for next component name
484 * directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set
485 * component vnode returned in ni_vp (if it exists), locked.
486 * if result vnode is mounted on and crossing mount points,
487 * find mounted on vnode
488 * if more components of name, do next level at dirloop
489 * return the answer in ni_vp, locked if LOCKLEAF set
490 * if LOCKPARENT set, return locked parent in ni_dvp
491 * if WANTPARENT set, return unlocked parent in ni_dvp
494 lookup(struct nameidata *ndp)
496 char *cp; /* pointer into pathname argument */
497 struct vnode *dp = 0; /* the directory we are searching */
498 struct vnode *tdp; /* saved dp */
499 struct mount *mp; /* mount table entry */
501 int docache; /* == 0 do not cache last component */
502 int wantparent; /* 1 => wantparent or lockparent flag */
503 int rdonly; /* lookup read-only flag bit */
505 int dpunlocked = 0; /* dp has already been unlocked */
506 struct componentname *cnp = &ndp->ni_cnd;
507 int vfslocked; /* VFS Giant state for child */
508 int dvfslocked; /* VFS Giant state for parent */
513 * Setup: break out flag bits into variables.
515 dvfslocked = (ndp->ni_cnd.cn_flags & GIANTHELD) != 0;
517 ndp->ni_cnd.cn_flags &= ~GIANTHELD;
518 wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT);
519 KASSERT(cnp->cn_nameiop == LOOKUP || wantparent,
520 ("CREATE, DELETE, RENAME require LOCKPARENT or WANTPARENT."));
521 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE;
522 if (cnp->cn_nameiop == DELETE ||
523 (wantparent && cnp->cn_nameiop != CREATE &&
524 cnp->cn_nameiop != LOOKUP))
526 rdonly = cnp->cn_flags & RDONLY;
527 cnp->cn_flags &= ~ISSYMLINK;
530 * We use shared locks until we hit the parent of the last cn then
531 * we adjust based on the requesting flags.
534 cnp->cn_lkflags = LK_SHARED;
536 cnp->cn_lkflags = LK_EXCLUSIVE;
537 dp = ndp->ni_startdir;
538 ndp->ni_startdir = NULLVP;
540 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | LK_RETRY));
544 * Search a new directory.
546 * The last component of the filename is left accessible via
547 * cnp->cn_nameptr for callers that need the name. Callers needing
548 * the name set the SAVENAME flag. When done, they assume
549 * responsibility for freeing the pathname buffer.
552 for (cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++)
554 cnp->cn_namelen = cp - cnp->cn_nameptr;
555 if (cnp->cn_namelen > NAME_MAX) {
556 error = ENAMETOOLONG;
559 #ifdef NAMEI_DIAGNOSTIC
562 printf("{%s}: ", cnp->cn_nameptr);
565 ndp->ni_pathlen -= cnp->cn_namelen;
569 * Replace multiple slashes by a single slash and trailing slashes
570 * by a null. This must be done before VOP_LOOKUP() because some
571 * fs's don't know about trailing slashes. Remember if there were
572 * trailing slashes to handle symlinks, existing non-directories
573 * and non-existing files that won't be directories specially later.
575 while (*cp == '/' && (cp[1] == '/' || cp[1] == '\0')) {
579 *ndp->ni_next = '\0';
580 cnp->cn_flags |= TRAILINGSLASH;
585 cnp->cn_flags |= MAKEENTRY;
586 if (*cp == '\0' && docache == 0)
587 cnp->cn_flags &= ~MAKEENTRY;
588 if (cnp->cn_namelen == 2 &&
589 cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.')
590 cnp->cn_flags |= ISDOTDOT;
592 cnp->cn_flags &= ~ISDOTDOT;
593 if (*ndp->ni_next == 0)
594 cnp->cn_flags |= ISLASTCN;
596 cnp->cn_flags &= ~ISLASTCN;
598 if ((cnp->cn_flags & ISLASTCN) != 0 &&
599 cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.' &&
600 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
606 * Check for degenerate name (e.g. / or "")
607 * which is a way of talking about a directory,
608 * e.g. like "/." or ".".
610 if (cnp->cn_nameptr[0] == '\0') {
611 if (dp->v_type != VDIR) {
615 if (cnp->cn_nameiop != LOOKUP) {
625 if (cnp->cn_flags & AUDITVNODE1)
626 AUDIT_ARG_VNODE1(dp);
627 else if (cnp->cn_flags & AUDITVNODE2)
628 AUDIT_ARG_VNODE2(dp);
630 if (!(cnp->cn_flags & (LOCKPARENT | LOCKLEAF)))
632 /* XXX This should probably move to the top of function. */
633 if (cnp->cn_flags & SAVESTART)
634 panic("lookup: SAVESTART");
639 * Handle "..": five special cases.
640 * 0. If doing a capability lookup, return ENOTCAPABLE (this is a
641 * fairly conservative design choice, but it's the only one that we
642 * are satisfied guarantees the property we're looking for).
643 * 1. Return an error if this is the last component of
644 * the name and the operation is DELETE or RENAME.
645 * 2. If at root directory (e.g. after chroot)
646 * or at absolute root directory
647 * then ignore it so can't get out.
648 * 3. If this vnode is the root of a mounted
649 * filesystem, then replace it with the
650 * vnode which was mounted on so we take the
651 * .. in the other filesystem.
652 * 4. If the vnode is the top directory of
653 * the jail or chroot, don't let them out.
655 if (cnp->cn_flags & ISDOTDOT) {
656 if (ndp->ni_strictrelative != 0) {
658 if (KTRPOINT(curthread, KTR_CAPFAIL))
659 ktrcapfail(CAPFAIL_LOOKUP, 0, 0);
664 if ((cnp->cn_flags & ISLASTCN) != 0 &&
665 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
670 for (pr = cnp->cn_cred->cr_prison; pr != NULL;
672 if (dp == pr->pr_root)
674 if (dp == ndp->ni_rootdir ||
675 dp == ndp->ni_topdir ||
678 ((dp->v_vflag & VV_ROOT) != 0 &&
679 (cnp->cn_flags & NOCROSSMOUNT) != 0)) {
682 vfslocked = VFS_LOCK_GIANT(dp->v_mount);
686 if ((dp->v_vflag & VV_ROOT) == 0)
688 if (dp->v_iflag & VI_DOOMED) { /* forced unmount */
693 dp = dp->v_mount->mnt_vnodecovered;
694 tvfslocked = dvfslocked;
695 dvfslocked = VFS_LOCK_GIANT(dp->v_mount);
698 VFS_UNLOCK_GIANT(tvfslocked);
700 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags |
706 * We now have a segment name to search for, and a directory to search.
710 if ((cnp->cn_flags & NOMACCHECK) == 0) {
711 error = mac_vnode_check_lookup(cnp->cn_thread->td_ucred, dp,
719 ASSERT_VOP_LOCKED(dp, "lookup");
720 VNASSERT(vfslocked == 0, dp, ("lookup: vfslocked %d", vfslocked));
722 * If we have a shared lock we may need to upgrade the lock for the
725 if (dp != vp_crossmp &&
726 VOP_ISLOCKED(dp) == LK_SHARED &&
727 (cnp->cn_flags & ISLASTCN) && (cnp->cn_flags & LOCKPARENT))
728 vn_lock(dp, LK_UPGRADE|LK_RETRY);
730 * If we're looking up the last component and we need an exclusive
731 * lock, adjust our lkflags.
733 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags))
734 cnp->cn_lkflags = LK_EXCLUSIVE;
735 #ifdef NAMEI_DIAGNOSTIC
736 vprint("lookup in", dp);
738 lkflags_save = cnp->cn_lkflags;
739 cnp->cn_lkflags = compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags);
740 if ((error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp)) != 0) {
741 cnp->cn_lkflags = lkflags_save;
742 KASSERT(ndp->ni_vp == NULL, ("leaf should be empty"));
743 #ifdef NAMEI_DIAGNOSTIC
744 printf("not found\n");
746 if ((error == ENOENT) &&
747 (dp->v_vflag & VV_ROOT) && (dp->v_mount != NULL) &&
748 (dp->v_mount->mnt_flag & MNT_UNION)) {
750 dp = dp->v_mount->mnt_vnodecovered;
751 tvfslocked = dvfslocked;
752 dvfslocked = VFS_LOCK_GIANT(dp->v_mount);
755 VFS_UNLOCK_GIANT(tvfslocked);
757 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags |
762 if (error != EJUSTRETURN)
765 * At this point, we know we're at the end of the
766 * pathname. If creating / renaming, we can consider
767 * allowing the file or directory to be created / renamed,
768 * provided we're not on a read-only filesystem.
774 /* trailing slash only allowed for directories */
775 if ((cnp->cn_flags & TRAILINGSLASH) &&
776 !(cnp->cn_flags & WILLBEDIR)) {
780 if ((cnp->cn_flags & LOCKPARENT) == 0)
783 * We return with ni_vp NULL to indicate that the entry
784 * doesn't currently exist, leaving a pointer to the
785 * (possibly locked) directory vnode in ndp->ni_dvp.
787 if (cnp->cn_flags & SAVESTART) {
788 ndp->ni_startdir = ndp->ni_dvp;
789 VREF(ndp->ni_startdir);
793 cnp->cn_lkflags = lkflags_save;
794 #ifdef NAMEI_DIAGNOSTIC
798 * Take into account any additional components consumed by
799 * the underlying filesystem.
801 if (cnp->cn_consume > 0) {
802 cnp->cn_nameptr += cnp->cn_consume;
803 ndp->ni_next += cnp->cn_consume;
804 ndp->ni_pathlen -= cnp->cn_consume;
809 vfslocked = VFS_LOCK_GIANT(dp->v_mount);
812 * Check to see if the vnode has been mounted on;
813 * if so find the root of the mounted filesystem.
815 while (dp->v_type == VDIR && (mp = dp->v_mountedhere) &&
816 (cnp->cn_flags & NOCROSSMOUNT) == 0) {
820 VFS_UNLOCK_GIANT(vfslocked);
821 vfslocked = VFS_LOCK_GIANT(mp);
822 if (dp != ndp->ni_dvp)
826 VFS_UNLOCK_GIANT(dvfslocked);
829 ndp->ni_dvp = vp_crossmp;
830 error = VFS_ROOT(mp, compute_cn_lkflags(mp, cnp->cn_lkflags),
833 if (vn_lock(vp_crossmp, LK_SHARED | LK_NOWAIT))
834 panic("vp_crossmp exclusively locked or reclaimed");
839 ndp->ni_vp = dp = tdp;
843 * Check for symbolic link
845 if ((dp->v_type == VLNK) &&
846 ((cnp->cn_flags & FOLLOW) || (cnp->cn_flags & TRAILINGSLASH) ||
847 *ndp->ni_next == '/')) {
848 cnp->cn_flags |= ISSYMLINK;
849 if (dp->v_iflag & VI_DOOMED) {
851 * We can't know whether the directory was mounted with
852 * NOSYMFOLLOW, so we can't follow safely.
857 if (dp->v_mount->mnt_flag & MNT_NOSYMFOLLOW) {
862 * Symlink code always expects an unlocked dvp.
864 if (ndp->ni_dvp != ndp->ni_vp)
865 VOP_UNLOCK(ndp->ni_dvp, 0);
871 * Not a symbolic link that we will follow. Continue with the
872 * next component if there is any; otherwise, we're done.
874 KASSERT((cnp->cn_flags & ISLASTCN) || *ndp->ni_next == '/',
875 ("lookup: invalid path state."));
876 if (*ndp->ni_next == '/') {
877 cnp->cn_nameptr = ndp->ni_next;
878 while (*cnp->cn_nameptr == '/') {
882 if (ndp->ni_dvp != dp)
886 VFS_UNLOCK_GIANT(dvfslocked);
887 dvfslocked = vfslocked; /* dp becomes dvp in dirloop */
892 * If we're processing a path with a trailing slash,
893 * check that the end result is a directory.
895 if ((cnp->cn_flags & TRAILINGSLASH) && dp->v_type != VDIR) {
900 * Disallow directory write attempts on read-only filesystems.
903 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
907 if (cnp->cn_flags & SAVESTART) {
908 ndp->ni_startdir = ndp->ni_dvp;
909 VREF(ndp->ni_startdir);
912 if (ndp->ni_dvp != dp)
916 VFS_UNLOCK_GIANT(dvfslocked);
918 } else if ((cnp->cn_flags & LOCKPARENT) == 0 && ndp->ni_dvp != dp)
919 VOP_UNLOCK(ndp->ni_dvp, 0);
921 if (cnp->cn_flags & AUDITVNODE1)
922 AUDIT_ARG_VNODE1(dp);
923 else if (cnp->cn_flags & AUDITVNODE2)
924 AUDIT_ARG_VNODE2(dp);
926 if ((cnp->cn_flags & LOCKLEAF) == 0)
930 * Because of lookup_shared we may have the vnode shared locked, but
931 * the caller may want it to be exclusively locked.
933 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags) &&
934 VOP_ISLOCKED(dp) != LK_EXCLUSIVE) {
935 vn_lock(dp, LK_UPGRADE | LK_RETRY);
936 if (dp->v_iflag & VI_DOOMED) {
941 if (vfslocked && dvfslocked)
942 VFS_UNLOCK_GIANT(dvfslocked); /* Only need one */
943 if (vfslocked || dvfslocked)
944 ndp->ni_cnd.cn_flags |= GIANTHELD;
948 if (dp != ndp->ni_dvp)
955 VFS_UNLOCK_GIANT(vfslocked);
956 VFS_UNLOCK_GIANT(dvfslocked);
957 ndp->ni_cnd.cn_flags &= ~GIANTHELD;
963 * relookup - lookup a path name component
964 * Used by lookup to re-acquire things.
967 relookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp)
969 struct vnode *dp = 0; /* the directory we are searching */
970 int wantparent; /* 1 => wantparent or lockparent flag */
971 int rdonly; /* lookup read-only flag bit */
974 KASSERT(cnp->cn_flags & ISLASTCN,
975 ("relookup: Not given last component."));
977 * Setup: break out flag bits into variables.
979 wantparent = cnp->cn_flags & (LOCKPARENT|WANTPARENT);
980 KASSERT(wantparent, ("relookup: parent not wanted."));
981 rdonly = cnp->cn_flags & RDONLY;
982 cnp->cn_flags &= ~ISSYMLINK;
984 cnp->cn_lkflags = LK_EXCLUSIVE;
985 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY);
988 * Search a new directory.
990 * The last component of the filename is left accessible via
991 * cnp->cn_nameptr for callers that need the name. Callers needing
992 * the name set the SAVENAME flag. When done, they assume
993 * responsibility for freeing the pathname buffer.
995 #ifdef NAMEI_DIAGNOSTIC
996 printf("{%s}: ", cnp->cn_nameptr);
1000 * Check for "" which represents the root directory after slash
1003 if (cnp->cn_nameptr[0] == '\0') {
1005 * Support only LOOKUP for "/" because lookup()
1006 * can't succeed for CREATE, DELETE and RENAME.
1008 KASSERT(cnp->cn_nameiop == LOOKUP, ("nameiop must be LOOKUP"));
1009 KASSERT(dp->v_type == VDIR, ("dp is not a directory"));
1011 if (!(cnp->cn_flags & LOCKLEAF))
1014 /* XXX This should probably move to the top of function. */
1015 if (cnp->cn_flags & SAVESTART)
1016 panic("lookup: SAVESTART");
1020 if (cnp->cn_flags & ISDOTDOT)
1021 panic ("relookup: lookup on dot-dot");
1024 * We now have a segment name to search for, and a directory to search.
1026 #ifdef NAMEI_DIAGNOSTIC
1027 vprint("search in:", dp);
1029 if ((error = VOP_LOOKUP(dp, vpp, cnp)) != 0) {
1030 KASSERT(*vpp == NULL, ("leaf should be empty"));
1031 if (error != EJUSTRETURN)
1034 * If creating and at end of pathname, then can consider
1035 * allowing file to be created.
1041 /* ASSERT(dvp == ndp->ni_startdir) */
1042 if (cnp->cn_flags & SAVESTART)
1044 if ((cnp->cn_flags & LOCKPARENT) == 0)
1047 * We return with ni_vp NULL to indicate that the entry
1048 * doesn't currently exist, leaving a pointer to the
1049 * (possibly locked) directory vnode in ndp->ni_dvp.
1057 * Disallow directory write attempts on read-only filesystems.
1060 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
1069 * Set the parent lock/ref state to the requested state.
1071 if ((cnp->cn_flags & LOCKPARENT) == 0 && dvp != dp) {
1076 } else if (!wantparent)
1079 * Check for symbolic link
1081 KASSERT(dp->v_type != VLNK || !(cnp->cn_flags & FOLLOW),
1082 ("relookup: symlink found.\n"));
1084 /* ASSERT(dvp == ndp->ni_startdir) */
1085 if (cnp->cn_flags & SAVESTART)
1088 if ((cnp->cn_flags & LOCKLEAF) == 0)
1098 * Free data allocated by namei(); see namei(9) for details.
1101 NDFREE(struct nameidata *ndp, const u_int flags)
1109 if (!(flags & NDF_NO_FREE_PNBUF) &&
1110 (ndp->ni_cnd.cn_flags & HASBUF)) {
1111 uma_zfree(namei_zone, ndp->ni_cnd.cn_pnbuf);
1112 ndp->ni_cnd.cn_flags &= ~HASBUF;
1114 if (!(flags & NDF_NO_VP_UNLOCK) &&
1115 (ndp->ni_cnd.cn_flags & LOCKLEAF) && ndp->ni_vp)
1117 if (!(flags & NDF_NO_VP_RELE) && ndp->ni_vp) {
1126 VOP_UNLOCK(ndp->ni_vp, 0);
1127 if (!(flags & NDF_NO_DVP_UNLOCK) &&
1128 (ndp->ni_cnd.cn_flags & LOCKPARENT) &&
1129 ndp->ni_dvp != ndp->ni_vp)
1131 if (!(flags & NDF_NO_DVP_RELE) &&
1132 (ndp->ni_cnd.cn_flags & (LOCKPARENT|WANTPARENT))) {
1141 VOP_UNLOCK(ndp->ni_dvp, 0);
1142 if (!(flags & NDF_NO_STARTDIR_RELE) &&
1143 (ndp->ni_cnd.cn_flags & SAVESTART)) {
1144 vrele(ndp->ni_startdir);
1145 ndp->ni_startdir = NULL;
1150 * Determine if there is a suitable alternate filename under the specified
1151 * prefix for the specified path. If the create flag is set, then the
1152 * alternate prefix will be used so long as the parent directory exists.
1153 * This is used by the various compatiblity ABIs so that Linux binaries prefer
1154 * files under /compat/linux for example. The chosen path (whether under
1155 * the prefix or under /) is returned in a kernel malloc'd buffer pointed
1156 * to by pathbuf. The caller is responsible for free'ing the buffer from
1157 * the M_TEMP bucket if one is returned.
1160 kern_alternate_path(struct thread *td, const char *prefix, const char *path,
1161 enum uio_seg pathseg, char **pathbuf, int create, int dirfd)
1163 struct nameidata nd, ndroot;
1164 char *ptr, *buf, *cp;
1168 buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
1171 /* Copy the prefix into the new pathname as a starting point. */
1172 len = strlcpy(buf, prefix, MAXPATHLEN);
1173 if (len >= MAXPATHLEN) {
1178 sz = MAXPATHLEN - len;
1181 /* Append the filename to the prefix. */
1182 if (pathseg == UIO_SYSSPACE)
1183 error = copystr(path, ptr, sz, &len);
1185 error = copyinstr(path, ptr, sz, &len);
1193 /* Only use a prefix with absolute pathnames. */
1199 if (dirfd != AT_FDCWD) {
1201 * We want the original because the "prefix" is
1202 * included in the already opened dirfd.
1204 bcopy(ptr, buf, len);
1209 * We know that there is a / somewhere in this pathname.
1210 * Search backwards for it, to find the file's parent dir
1211 * to see if it exists in the alternate tree. If it does,
1212 * and we want to create a file (cflag is set). We don't
1213 * need to worry about the root comparison in this case.
1217 for (cp = &ptr[len] - 1; *cp != '/'; cp--);
1220 NDINIT(&nd, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, buf, td);
1226 NDINIT(&nd, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, buf, td);
1233 * We now compare the vnode of the prefix to the one
1234 * vnode asked. If they resolve to be the same, then we
1235 * ignore the match so that the real root gets used.
1236 * This avoids the problem of traversing "../.." to find the
1237 * root directory and never finding it, because "/" resolves
1238 * to the emulation root directory. This is expensive :-(
1240 NDINIT(&ndroot, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, prefix,
1243 /* We shouldn't ever get an error from this namei(). */
1244 error = namei(&ndroot);
1246 if (nd.ni_vp == ndroot.ni_vp)
1249 NDFREE(&ndroot, NDF_ONLY_PNBUF);
1250 vrele(ndroot.ni_vp);
1251 VFS_UNLOCK_GIANT(NDHASGIANT(&ndroot));
1255 NDFREE(&nd, NDF_ONLY_PNBUF);
1257 VFS_UNLOCK_GIANT(NDHASGIANT(&nd));
1260 /* If there was an error, use the original path name. */
1262 bcopy(ptr, buf, len);