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.
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23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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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);
167 * Don't allow empty pathnames.
169 if (!error && *cnp->cn_pnbuf == '\0')
172 #ifdef CAPABILITY_MODE
174 * In capability mode, lookups must be "strictly relative" (i.e.
175 * not an absolute path, and not containing '..' components) to
176 * a real file descriptor, not the pseudo-descriptor AT_FDCWD.
178 if (IN_CAPABILITY_MODE(td)) {
179 ndp->ni_strictrelative = 1;
180 if (ndp->ni_dirfd == AT_FDCWD)
185 uma_zfree(namei_zone, cnp->cn_pnbuf);
187 cnp->cn_pnbuf = NULL;
188 cnp->cn_nameptr = NULL;
195 if (KTRPOINT(td, KTR_NAMEI)) {
196 KASSERT(cnp->cn_thread == curthread,
197 ("namei not using curthread"));
198 ktrnamei(cnp->cn_pnbuf);
202 * Get starting point for the translation.
205 ndp->ni_rootdir = fdp->fd_rdir;
206 ndp->ni_topdir = fdp->fd_jdir;
209 * If we are auditing the kernel pathname, save the user pathname.
211 if (cnp->cn_flags & AUDITVNODE1)
212 AUDIT_ARG_UPATH1(td, ndp->ni_dirfd, cnp->cn_pnbuf);
213 if (cnp->cn_flags & AUDITVNODE2)
214 AUDIT_ARG_UPATH2(td, ndp->ni_dirfd, cnp->cn_pnbuf);
217 if (cnp->cn_pnbuf[0] != '/') {
218 if (ndp->ni_startdir != NULL) {
219 dp = ndp->ni_startdir;
221 } else if (ndp->ni_dirfd != AT_FDCWD) {
222 if (cnp->cn_flags & AUDITVNODE1)
223 AUDIT_ARG_ATFD1(ndp->ni_dirfd);
224 if (cnp->cn_flags & AUDITVNODE2)
225 AUDIT_ARG_ATFD2(ndp->ni_dirfd);
226 error = fgetvp_rights(td, ndp->ni_dirfd,
227 ndp->ni_rightsneeded | CAP_LOOKUP,
228 &(ndp->ni_baserights), &dp);
231 * Lookups relative to a capability must also be
234 * Note that a capability with rights CAP_MASK_VALID
235 * is treated exactly like a regular file descriptor.
237 if (ndp->ni_baserights != CAP_MASK_VALID)
238 ndp->ni_strictrelative = 1;
241 if (error != 0 || dp != NULL) {
242 FILEDESC_SUNLOCK(fdp);
243 if (error == 0 && dp->v_type != VDIR) {
244 vfslocked = VFS_LOCK_GIANT(dp->v_mount);
246 VFS_UNLOCK_GIANT(vfslocked);
251 uma_zfree(namei_zone, cnp->cn_pnbuf);
253 cnp->cn_pnbuf = NULL;
254 cnp->cn_nameptr = NULL;
262 FILEDESC_SUNLOCK(fdp);
263 if (ndp->ni_startdir != NULL) {
264 vfslocked = VFS_LOCK_GIANT(ndp->ni_startdir->v_mount);
265 vrele(ndp->ni_startdir);
266 VFS_UNLOCK_GIANT(vfslocked);
269 SDT_PROBE(vfs, namei, lookup, entry, dp, cnp->cn_pnbuf,
270 cnp->cn_flags, 0, 0);
271 vfslocked = VFS_LOCK_GIANT(dp->v_mount);
274 * Check if root directory should replace current directory.
275 * Done at start of translation and after symbolic link.
277 cnp->cn_nameptr = cnp->cn_pnbuf;
278 if (*(cnp->cn_nameptr) == '/') {
280 VFS_UNLOCK_GIANT(vfslocked);
281 if (ndp->ni_strictrelative != 0)
282 return (ENOTCAPABLE);
283 while (*(cnp->cn_nameptr) == '/') {
287 dp = ndp->ni_rootdir;
288 vfslocked = VFS_LOCK_GIANT(dp->v_mount);
292 ndp->ni_cnd.cn_flags |= GIANTHELD;
293 ndp->ni_startdir = dp;
296 uma_zfree(namei_zone, cnp->cn_pnbuf);
298 cnp->cn_pnbuf = NULL;
299 cnp->cn_nameptr = NULL;
301 SDT_PROBE(vfs, namei, lookup, return, error, NULL, 0,
305 vfslocked = (ndp->ni_cnd.cn_flags & GIANTHELD) != 0;
306 ndp->ni_cnd.cn_flags &= ~GIANTHELD;
308 * If not a symbolic link, we're done.
310 if ((cnp->cn_flags & ISSYMLINK) == 0) {
311 if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) {
312 uma_zfree(namei_zone, cnp->cn_pnbuf);
314 cnp->cn_pnbuf = NULL;
315 cnp->cn_nameptr = NULL;
318 cnp->cn_flags |= HASBUF;
320 if ((cnp->cn_flags & MPSAFE) == 0) {
321 VFS_UNLOCK_GIANT(vfslocked);
322 } else if (vfslocked)
323 ndp->ni_cnd.cn_flags |= GIANTHELD;
324 SDT_PROBE(vfs, namei, lookup, return, 0, ndp->ni_vp,
328 if (ndp->ni_loopcnt++ >= MAXSYMLINKS) {
333 if ((cnp->cn_flags & NOMACCHECK) == 0) {
334 error = mac_vnode_check_readlink(td->td_ucred,
340 if (ndp->ni_pathlen > 1)
341 cp = uma_zalloc(namei_zone, M_WAITOK);
345 aiov.iov_len = MAXPATHLEN;
346 auio.uio_iov = &aiov;
349 auio.uio_rw = UIO_READ;
350 auio.uio_segflg = UIO_SYSSPACE;
352 auio.uio_resid = MAXPATHLEN;
353 error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred);
355 if (ndp->ni_pathlen > 1)
356 uma_zfree(namei_zone, cp);
359 linklen = MAXPATHLEN - auio.uio_resid;
361 if (ndp->ni_pathlen > 1)
362 uma_zfree(namei_zone, cp);
366 if (linklen + ndp->ni_pathlen >= MAXPATHLEN) {
367 if (ndp->ni_pathlen > 1)
368 uma_zfree(namei_zone, cp);
369 error = ENAMETOOLONG;
372 if (ndp->ni_pathlen > 1) {
373 bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen);
374 uma_zfree(namei_zone, cnp->cn_pnbuf);
377 cnp->cn_pnbuf[linklen] = '\0';
378 ndp->ni_pathlen += linklen;
382 uma_zfree(namei_zone, cnp->cn_pnbuf);
384 cnp->cn_pnbuf = NULL;
385 cnp->cn_nameptr = NULL;
390 VFS_UNLOCK_GIANT(vfslocked);
391 SDT_PROBE(vfs, namei, lookup, return, error, NULL, 0, 0, 0);
396 compute_cn_lkflags(struct mount *mp, int lkflags, int cnflags)
399 if (mp == NULL || ((lkflags & LK_SHARED) &&
400 (!(mp->mnt_kern_flag & MNTK_LOOKUP_SHARED) ||
401 ((cnflags & ISDOTDOT) &&
402 (mp->mnt_kern_flag & MNTK_LOOKUP_EXCL_DOTDOT))))) {
403 lkflags &= ~LK_SHARED;
404 lkflags |= LK_EXCLUSIVE;
410 needs_exclusive_leaf(struct mount *mp, int flags)
414 * Intermediate nodes can use shared locks, we only need to
415 * force an exclusive lock for leaf nodes.
417 if ((flags & (ISLASTCN | LOCKLEAF)) != (ISLASTCN | LOCKLEAF))
420 /* Always use exclusive locks if LOCKSHARED isn't set. */
421 if (!(flags & LOCKSHARED))
425 * For lookups during open(), if the mount point supports
426 * extended shared operations, then use a shared lock for the
427 * leaf node, otherwise use an exclusive lock.
429 if (flags & ISOPEN) {
431 (mp->mnt_kern_flag & MNTK_EXTENDED_SHARED))
438 * Lookup requests outside of open() that specify LOCKSHARED
439 * only need a shared lock on the leaf vnode.
446 * This is a very central and rather complicated routine.
448 * The pathname is pointed to by ni_ptr and is of length ni_pathlen.
449 * The starting directory is taken from ni_startdir. The pathname is
450 * descended until done, or a symbolic link is encountered. The variable
451 * ni_more is clear if the path is completed; it is set to one if a
452 * symbolic link needing interpretation is encountered.
454 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on
455 * whether the name is to be looked up, created, renamed, or deleted.
456 * When CREATE, RENAME, or DELETE is specified, information usable in
457 * creating, renaming, or deleting a directory entry may be calculated.
458 * If flag has LOCKPARENT or'ed into it, the parent directory is returned
459 * locked. If flag has WANTPARENT or'ed into it, the parent directory is
460 * returned unlocked. Otherwise the parent directory is not returned. If
461 * the target of the pathname exists and LOCKLEAF is or'ed into the flag
462 * the target is returned locked, otherwise it is returned unlocked.
463 * When creating or renaming and LOCKPARENT is specified, the target may not
464 * be ".". When deleting and LOCKPARENT is specified, the target may be ".".
466 * Overall outline of lookup:
469 * identify next component of name at ndp->ni_ptr
470 * handle degenerate case where name is null string
471 * if .. and crossing mount points and on mounted filesys, find parent
472 * call VOP_LOOKUP routine for next component name
473 * directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set
474 * component vnode returned in ni_vp (if it exists), locked.
475 * if result vnode is mounted on and crossing mount points,
476 * find mounted on vnode
477 * if more components of name, do next level at dirloop
478 * return the answer in ni_vp, locked if LOCKLEAF set
479 * if LOCKPARENT set, return locked parent in ni_dvp
480 * if WANTPARENT set, return unlocked parent in ni_dvp
483 lookup(struct nameidata *ndp)
485 char *cp; /* pointer into pathname argument */
486 struct vnode *dp = 0; /* the directory we are searching */
487 struct vnode *tdp; /* saved dp */
488 struct mount *mp; /* mount table entry */
490 int docache; /* == 0 do not cache last component */
491 int wantparent; /* 1 => wantparent or lockparent flag */
492 int rdonly; /* lookup read-only flag bit */
494 int dpunlocked = 0; /* dp has already been unlocked */
495 struct componentname *cnp = &ndp->ni_cnd;
496 int vfslocked; /* VFS Giant state for child */
497 int dvfslocked; /* VFS Giant state for parent */
503 * Setup: break out flag bits into variables.
505 dvfslocked = (ndp->ni_cnd.cn_flags & GIANTHELD) != 0;
508 ndp->ni_cnd.cn_flags &= ~GIANTHELD;
509 wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT);
510 KASSERT(cnp->cn_nameiop == LOOKUP || wantparent,
511 ("CREATE, DELETE, RENAME require LOCKPARENT or WANTPARENT."));
512 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE;
513 if (cnp->cn_nameiop == DELETE ||
514 (wantparent && cnp->cn_nameiop != CREATE &&
515 cnp->cn_nameiop != LOOKUP))
517 rdonly = cnp->cn_flags & RDONLY;
518 cnp->cn_flags &= ~ISSYMLINK;
521 * We use shared locks until we hit the parent of the last cn then
522 * we adjust based on the requesting flags.
525 cnp->cn_lkflags = LK_SHARED;
527 cnp->cn_lkflags = LK_EXCLUSIVE;
528 dp = ndp->ni_startdir;
529 ndp->ni_startdir = NULLVP;
531 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | LK_RETRY,
536 * Search a new directory.
538 * The last component of the filename is left accessible via
539 * cnp->cn_nameptr for callers that need the name. Callers needing
540 * the name set the SAVENAME flag. When done, they assume
541 * responsibility for freeing the pathname buffer.
544 for (cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++)
546 cnp->cn_namelen = cp - cnp->cn_nameptr;
547 if (cnp->cn_namelen > NAME_MAX) {
548 error = ENAMETOOLONG;
551 #ifdef NAMEI_DIAGNOSTIC
554 printf("{%s}: ", cnp->cn_nameptr);
557 ndp->ni_pathlen -= cnp->cn_namelen;
561 * Replace multiple slashes by a single slash and trailing slashes
562 * by a null. This must be done before VOP_LOOKUP() because some
563 * fs's don't know about trailing slashes. Remember if there were
564 * trailing slashes to handle symlinks, existing non-directories
565 * and non-existing files that won't be directories specially later.
567 while (*cp == '/' && (cp[1] == '/' || cp[1] == '\0')) {
571 *ndp->ni_next = '\0';
572 cnp->cn_flags |= TRAILINGSLASH;
577 cnp->cn_flags |= MAKEENTRY;
578 if (*cp == '\0' && docache == 0)
579 cnp->cn_flags &= ~MAKEENTRY;
580 if (cnp->cn_namelen == 2 &&
581 cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.')
582 cnp->cn_flags |= ISDOTDOT;
584 cnp->cn_flags &= ~ISDOTDOT;
585 if (*ndp->ni_next == 0)
586 cnp->cn_flags |= ISLASTCN;
588 cnp->cn_flags &= ~ISLASTCN;
590 if ((cnp->cn_flags & ISLASTCN) != 0 &&
591 cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.' &&
592 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
598 * Check for degenerate name (e.g. / or "")
599 * which is a way of talking about a directory,
600 * e.g. like "/." or ".".
602 if (cnp->cn_nameptr[0] == '\0') {
603 if (dp->v_type != VDIR) {
607 if (cnp->cn_nameiop != LOOKUP) {
617 if (cnp->cn_flags & AUDITVNODE1)
618 AUDIT_ARG_VNODE1(dp);
619 else if (cnp->cn_flags & AUDITVNODE2)
620 AUDIT_ARG_VNODE2(dp);
622 if (!(cnp->cn_flags & (LOCKPARENT | LOCKLEAF)))
624 /* XXX This should probably move to the top of function. */
625 if (cnp->cn_flags & SAVESTART)
626 panic("lookup: SAVESTART");
631 * Handle "..": five special cases.
632 * 0. If doing a capability lookup, return ENOTCAPABLE (this is a
633 * fairly conservative design choice, but it's the only one that we
634 * are satisfied guarantees the property we're looking for).
635 * 1. Return an error if this is the last component of
636 * the name and the operation is DELETE or RENAME.
637 * 2. If at root directory (e.g. after chroot)
638 * or at absolute root directory
639 * then ignore it so can't get out.
640 * 3. If this vnode is the root of a mounted
641 * filesystem, then replace it with the
642 * vnode which was mounted on so we take the
643 * .. in the other filesystem.
644 * 4. If the vnode is the top directory of
645 * the jail or chroot, don't let them out.
647 if (cnp->cn_flags & ISDOTDOT) {
648 if (ndp->ni_strictrelative != 0) {
652 if ((cnp->cn_flags & ISLASTCN) != 0 &&
653 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
658 for (pr = cnp->cn_cred->cr_prison; pr != NULL;
660 if (dp == pr->pr_root)
662 if (dp == ndp->ni_rootdir ||
663 dp == ndp->ni_topdir ||
666 ((dp->v_vflag & VV_ROOT) != 0 &&
667 (cnp->cn_flags & NOCROSSMOUNT) != 0)) {
670 vfslocked = VFS_LOCK_GIANT(dp->v_mount);
674 if ((dp->v_vflag & VV_ROOT) == 0)
676 if (dp->v_iflag & VI_DOOMED) { /* forced unmount */
681 dp = dp->v_mount->mnt_vnodecovered;
682 tvfslocked = dvfslocked;
683 dvfslocked = VFS_LOCK_GIANT(dp->v_mount);
686 VFS_UNLOCK_GIANT(tvfslocked);
688 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags |
689 LK_RETRY, ISDOTDOT));
694 * We now have a segment name to search for, and a directory to search.
698 if ((cnp->cn_flags & NOMACCHECK) == 0) {
699 error = mac_vnode_check_lookup(cnp->cn_thread->td_ucred, dp,
707 ASSERT_VOP_LOCKED(dp, "lookup");
708 VNASSERT(vfslocked == 0, dp, ("lookup: vfslocked %d", vfslocked));
710 * If we have a shared lock we may need to upgrade the lock for the
713 if (dp != vp_crossmp &&
714 VOP_ISLOCKED(dp) == LK_SHARED &&
715 (cnp->cn_flags & ISLASTCN) && (cnp->cn_flags & LOCKPARENT))
716 vn_lock(dp, LK_UPGRADE|LK_RETRY);
717 if ((dp->v_iflag & VI_DOOMED) != 0) {
722 * If we're looking up the last component and we need an exclusive
723 * lock, adjust our lkflags.
725 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags))
726 cnp->cn_lkflags = LK_EXCLUSIVE;
727 #ifdef NAMEI_DIAGNOSTIC
728 vprint("lookup in", dp);
730 lkflags_save = cnp->cn_lkflags;
731 cnp->cn_lkflags = compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags,
733 if ((error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp)) != 0) {
734 cnp->cn_lkflags = lkflags_save;
735 KASSERT(ndp->ni_vp == NULL, ("leaf should be empty"));
736 #ifdef NAMEI_DIAGNOSTIC
737 printf("not found\n");
739 if ((error == ENOENT) &&
740 (dp->v_vflag & VV_ROOT) && (dp->v_mount != NULL) &&
741 (dp->v_mount->mnt_flag & MNT_UNION)) {
743 dp = dp->v_mount->mnt_vnodecovered;
744 tvfslocked = dvfslocked;
745 dvfslocked = VFS_LOCK_GIANT(dp->v_mount);
748 VFS_UNLOCK_GIANT(tvfslocked);
750 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags |
751 LK_RETRY, cnp->cn_flags));
755 if (error != EJUSTRETURN)
758 * At this point, we know we're at the end of the
759 * pathname. If creating / renaming, we can consider
760 * allowing the file or directory to be created / renamed,
761 * provided we're not on a read-only filesystem.
767 /* trailing slash only allowed for directories */
768 if ((cnp->cn_flags & TRAILINGSLASH) &&
769 !(cnp->cn_flags & WILLBEDIR)) {
773 if ((cnp->cn_flags & LOCKPARENT) == 0)
776 * We return with ni_vp NULL to indicate that the entry
777 * doesn't currently exist, leaving a pointer to the
778 * (possibly locked) directory vnode in ndp->ni_dvp.
780 if (cnp->cn_flags & SAVESTART) {
781 ndp->ni_startdir = ndp->ni_dvp;
782 VREF(ndp->ni_startdir);
786 cnp->cn_lkflags = lkflags_save;
787 #ifdef NAMEI_DIAGNOSTIC
791 * Take into account any additional components consumed by
792 * the underlying filesystem.
794 if (cnp->cn_consume > 0) {
795 cnp->cn_nameptr += cnp->cn_consume;
796 ndp->ni_next += cnp->cn_consume;
797 ndp->ni_pathlen -= cnp->cn_consume;
802 vfslocked = VFS_LOCK_GIANT(dp->v_mount);
805 * Check to see if the vnode has been mounted on;
806 * if so find the root of the mounted filesystem.
808 while (dp->v_type == VDIR && (mp = dp->v_mountedhere) &&
809 (cnp->cn_flags & NOCROSSMOUNT) == 0) {
813 VFS_UNLOCK_GIANT(vfslocked);
814 vfslocked = VFS_LOCK_GIANT(mp);
815 if (dp != ndp->ni_dvp)
819 VFS_UNLOCK_GIANT(dvfslocked);
822 ndp->ni_dvp = vp_crossmp;
823 error = VFS_ROOT(mp, compute_cn_lkflags(mp, cnp->cn_lkflags,
824 cnp->cn_flags), &tdp);
826 if (vn_lock(vp_crossmp, LK_SHARED | LK_NOWAIT))
827 panic("vp_crossmp exclusively locked or reclaimed");
832 ndp->ni_vp = dp = tdp;
836 * Check for symbolic link
838 if ((dp->v_type == VLNK) &&
839 ((cnp->cn_flags & FOLLOW) || (cnp->cn_flags & TRAILINGSLASH) ||
840 *ndp->ni_next == '/')) {
841 cnp->cn_flags |= ISSYMLINK;
842 if (dp->v_iflag & VI_DOOMED) {
844 * We can't know whether the directory was mounted with
845 * NOSYMFOLLOW, so we can't follow safely.
850 if (dp->v_mount->mnt_flag & MNT_NOSYMFOLLOW) {
855 * Symlink code always expects an unlocked dvp.
857 if (ndp->ni_dvp != ndp->ni_vp) {
858 VOP_UNLOCK(ndp->ni_dvp, 0);
866 * Not a symbolic link that we will follow. Continue with the
867 * next component if there is any; otherwise, we're done.
869 KASSERT((cnp->cn_flags & ISLASTCN) || *ndp->ni_next == '/',
870 ("lookup: invalid path state."));
871 if (*ndp->ni_next == '/') {
872 cnp->cn_nameptr = ndp->ni_next;
873 while (*cnp->cn_nameptr == '/') {
877 if (ndp->ni_dvp != dp)
881 VFS_UNLOCK_GIANT(dvfslocked);
882 dvfslocked = vfslocked; /* dp becomes dvp in dirloop */
887 * If we're processing a path with a trailing slash,
888 * check that the end result is a directory.
890 if ((cnp->cn_flags & TRAILINGSLASH) && dp->v_type != VDIR) {
895 * Disallow directory write attempts on read-only filesystems.
898 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
902 if (cnp->cn_flags & SAVESTART) {
903 ndp->ni_startdir = ndp->ni_dvp;
904 VREF(ndp->ni_startdir);
908 if (ndp->ni_dvp != dp)
912 VFS_UNLOCK_GIANT(dvfslocked);
914 } else if ((cnp->cn_flags & LOCKPARENT) == 0 && ndp->ni_dvp != dp) {
915 VOP_UNLOCK(ndp->ni_dvp, 0);
919 if (cnp->cn_flags & AUDITVNODE1)
920 AUDIT_ARG_VNODE1(dp);
921 else if (cnp->cn_flags & AUDITVNODE2)
922 AUDIT_ARG_VNODE2(dp);
924 if ((cnp->cn_flags & LOCKLEAF) == 0)
928 * Because of lookup_shared we may have the vnode shared locked, but
929 * the caller may want it to be exclusively locked.
931 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags) &&
932 VOP_ISLOCKED(dp) != LK_EXCLUSIVE) {
933 vn_lock(dp, LK_UPGRADE | LK_RETRY);
934 if (dp->v_iflag & VI_DOOMED) {
939 if (vfslocked && dvfslocked)
940 VFS_UNLOCK_GIANT(dvfslocked); /* Only need one */
941 if (vfslocked || dvfslocked)
942 ndp->ni_cnd.cn_flags |= GIANTHELD;
946 if (ni_dvp_unlocked != 2) {
947 if (dp != ndp->ni_dvp && !ni_dvp_unlocked)
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);