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.
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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
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19 * may be used to endorse or promote products derived from this software
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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, "struct vnode *", "char *",
75 SDT_PROBE_DEFINE2(vfs, namei, lookup, 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_cleanup_cnp(struct componentname *cnp)
127 uma_zfree(namei_zone, cnp->cn_pnbuf);
129 cnp->cn_pnbuf = NULL;
130 cnp->cn_nameptr = NULL;
135 namei(struct nameidata *ndp)
137 struct filedesc *fdp; /* pointer to file descriptor state */
138 char *cp; /* pointer into pathname argument */
139 struct vnode *dp; /* the directory we are searching */
140 struct iovec aiov; /* uio for reading symbolic links */
143 struct componentname *cnp = &ndp->ni_cnd;
144 struct thread *td = cnp->cn_thread;
145 struct proc *p = td->td_proc;
147 ndp->ni_cnd.cn_cred = ndp->ni_cnd.cn_thread->td_ucred;
148 KASSERT(cnp->cn_cred && p, ("namei: bad cred/proc"));
149 KASSERT((cnp->cn_nameiop & (~OPMASK)) == 0,
150 ("namei: nameiop contaminated with flags"));
151 KASSERT((cnp->cn_flags & OPMASK) == 0,
152 ("namei: flags contaminated with nameiops"));
154 cnp->cn_flags &= ~LOCKSHARED;
157 /* We will set this ourselves if we need it. */
158 cnp->cn_flags &= ~TRAILINGSLASH;
161 * Get a buffer for the name to be translated, and copy the
162 * name into the buffer.
164 if ((cnp->cn_flags & HASBUF) == 0)
165 cnp->cn_pnbuf = uma_zalloc(namei_zone, M_WAITOK);
166 if (ndp->ni_segflg == UIO_SYSSPACE)
167 error = copystr(ndp->ni_dirp, cnp->cn_pnbuf,
168 MAXPATHLEN, (size_t *)&ndp->ni_pathlen);
170 error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf,
171 MAXPATHLEN, (size_t *)&ndp->ni_pathlen);
174 * Don't allow empty pathnames.
176 if (!error && *cnp->cn_pnbuf == '\0')
179 #ifdef CAPABILITY_MODE
181 * In capability mode, lookups must be "strictly relative" (i.e.
182 * not an absolute path, and not containing '..' components) to
183 * a real file descriptor, not the pseudo-descriptor AT_FDCWD.
185 if (error == 0 && IN_CAPABILITY_MODE(td) &&
186 (cnp->cn_flags & NOCAPCHECK) == 0) {
187 ndp->ni_strictrelative = 1;
188 if (ndp->ni_dirfd == AT_FDCWD) {
190 if (KTRPOINT(td, KTR_CAPFAIL))
191 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
198 namei_cleanup_cnp(cnp);
204 if (KTRPOINT(td, KTR_NAMEI)) {
205 KASSERT(cnp->cn_thread == curthread,
206 ("namei not using curthread"));
207 ktrnamei(cnp->cn_pnbuf);
211 * Get starting point for the translation.
214 ndp->ni_rootdir = fdp->fd_rdir;
215 ndp->ni_topdir = fdp->fd_jdir;
218 * If we are auditing the kernel pathname, save the user pathname.
220 if (cnp->cn_flags & AUDITVNODE1)
221 AUDIT_ARG_UPATH1(td, ndp->ni_dirfd, cnp->cn_pnbuf);
222 if (cnp->cn_flags & AUDITVNODE2)
223 AUDIT_ARG_UPATH2(td, ndp->ni_dirfd, cnp->cn_pnbuf);
226 if (cnp->cn_pnbuf[0] != '/') {
227 if (ndp->ni_startdir != NULL) {
228 dp = ndp->ni_startdir;
230 } else if (ndp->ni_dirfd != AT_FDCWD) {
233 rights = ndp->ni_rightsneeded;
234 cap_rights_set(&rights, CAP_LOOKUP);
236 if (cnp->cn_flags & AUDITVNODE1)
237 AUDIT_ARG_ATFD1(ndp->ni_dirfd);
238 if (cnp->cn_flags & AUDITVNODE2)
239 AUDIT_ARG_ATFD2(ndp->ni_dirfd);
240 error = fgetvp_rights(td, ndp->ni_dirfd,
241 &rights, &ndp->ni_filecaps, &dp);
244 * If file descriptor doesn't have all rights,
245 * all lookups relative to it must also be
249 if (!cap_rights_contains(&ndp->ni_filecaps.fc_rights,
251 ndp->ni_filecaps.fc_fcntls != CAP_FCNTL_ALL ||
252 ndp->ni_filecaps.fc_nioctls != -1) {
253 ndp->ni_strictrelative = 1;
257 if (error != 0 || dp != NULL) {
258 FILEDESC_SUNLOCK(fdp);
259 if (error == 0 && dp->v_type != VDIR) {
265 namei_cleanup_cnp(cnp);
272 FILEDESC_SUNLOCK(fdp);
273 if (ndp->ni_startdir != NULL)
274 vrele(ndp->ni_startdir);
276 SDT_PROBE(vfs, namei, lookup, entry, dp, cnp->cn_pnbuf,
277 cnp->cn_flags, 0, 0);
280 * Check if root directory should replace current directory.
281 * Done at start of translation and after symbolic link.
283 cnp->cn_nameptr = cnp->cn_pnbuf;
284 if (*(cnp->cn_nameptr) == '/') {
286 if (ndp->ni_strictrelative != 0) {
288 if (KTRPOINT(curthread, KTR_CAPFAIL))
289 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
291 namei_cleanup_cnp(cnp);
292 return (ENOTCAPABLE);
294 while (*(cnp->cn_nameptr) == '/') {
298 dp = ndp->ni_rootdir;
301 ndp->ni_startdir = dp;
304 namei_cleanup_cnp(cnp);
305 SDT_PROBE(vfs, namei, lookup, return, error, NULL, 0,
310 * If not a symbolic link, we're done.
312 if ((cnp->cn_flags & ISSYMLINK) == 0) {
313 if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) {
314 namei_cleanup_cnp(cnp);
316 cnp->cn_flags |= HASBUF;
318 SDT_PROBE(vfs, namei, lookup, return, 0, ndp->ni_vp,
322 if (ndp->ni_loopcnt++ >= MAXSYMLINKS) {
327 if ((cnp->cn_flags & NOMACCHECK) == 0) {
328 error = mac_vnode_check_readlink(td->td_ucred,
334 if (ndp->ni_pathlen > 1)
335 cp = uma_zalloc(namei_zone, M_WAITOK);
339 aiov.iov_len = MAXPATHLEN;
340 auio.uio_iov = &aiov;
343 auio.uio_rw = UIO_READ;
344 auio.uio_segflg = UIO_SYSSPACE;
346 auio.uio_resid = MAXPATHLEN;
347 error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred);
349 if (ndp->ni_pathlen > 1)
350 uma_zfree(namei_zone, cp);
353 linklen = MAXPATHLEN - auio.uio_resid;
355 if (ndp->ni_pathlen > 1)
356 uma_zfree(namei_zone, cp);
360 if (linklen + ndp->ni_pathlen >= MAXPATHLEN) {
361 if (ndp->ni_pathlen > 1)
362 uma_zfree(namei_zone, cp);
363 error = ENAMETOOLONG;
366 if (ndp->ni_pathlen > 1) {
367 bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen);
368 uma_zfree(namei_zone, cnp->cn_pnbuf);
371 cnp->cn_pnbuf[linklen] = '\0';
372 ndp->ni_pathlen += linklen;
376 namei_cleanup_cnp(cnp);
380 SDT_PROBE(vfs, namei, lookup, return, error, NULL, 0, 0, 0);
385 compute_cn_lkflags(struct mount *mp, int lkflags, int cnflags)
388 if (mp == NULL || ((lkflags & LK_SHARED) &&
389 (!(mp->mnt_kern_flag & MNTK_LOOKUP_SHARED) ||
390 ((cnflags & ISDOTDOT) &&
391 (mp->mnt_kern_flag & MNTK_LOOKUP_EXCL_DOTDOT))))) {
392 lkflags &= ~LK_SHARED;
393 lkflags |= LK_EXCLUSIVE;
399 needs_exclusive_leaf(struct mount *mp, int flags)
403 * Intermediate nodes can use shared locks, we only need to
404 * force an exclusive lock for leaf nodes.
406 if ((flags & (ISLASTCN | LOCKLEAF)) != (ISLASTCN | LOCKLEAF))
409 /* Always use exclusive locks if LOCKSHARED isn't set. */
410 if (!(flags & LOCKSHARED))
414 * For lookups during open(), if the mount point supports
415 * extended shared operations, then use a shared lock for the
416 * leaf node, otherwise use an exclusive lock.
418 if ((flags & ISOPEN) != 0)
419 return (!MNT_EXTENDED_SHARED(mp));
422 * Lookup requests outside of open() that specify LOCKSHARED
423 * only need a shared lock on the leaf vnode.
430 * This is a very central and rather complicated routine.
432 * The pathname is pointed to by ni_ptr and is of length ni_pathlen.
433 * The starting directory is taken from ni_startdir. The pathname is
434 * descended until done, or a symbolic link is encountered. The variable
435 * ni_more is clear if the path is completed; it is set to one if a
436 * symbolic link needing interpretation is encountered.
438 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on
439 * whether the name is to be looked up, created, renamed, or deleted.
440 * When CREATE, RENAME, or DELETE is specified, information usable in
441 * creating, renaming, or deleting a directory entry may be calculated.
442 * If flag has LOCKPARENT or'ed into it, the parent directory is returned
443 * locked. If flag has WANTPARENT or'ed into it, the parent directory is
444 * returned unlocked. Otherwise the parent directory is not returned. If
445 * the target of the pathname exists and LOCKLEAF is or'ed into the flag
446 * the target is returned locked, otherwise it is returned unlocked.
447 * When creating or renaming and LOCKPARENT is specified, the target may not
448 * be ".". When deleting and LOCKPARENT is specified, the target may be ".".
450 * Overall outline of lookup:
453 * identify next component of name at ndp->ni_ptr
454 * handle degenerate case where name is null string
455 * if .. and crossing mount points and on mounted filesys, find parent
456 * call VOP_LOOKUP routine for next component name
457 * directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set
458 * component vnode returned in ni_vp (if it exists), locked.
459 * if result vnode is mounted on and crossing mount points,
460 * find mounted on vnode
461 * if more components of name, do next level at dirloop
462 * return the answer in ni_vp, locked if LOCKLEAF set
463 * if LOCKPARENT set, return locked parent in ni_dvp
464 * if WANTPARENT set, return unlocked parent in ni_dvp
467 lookup(struct nameidata *ndp)
469 char *cp; /* pointer into pathname argument */
470 struct vnode *dp = 0; /* the directory we are searching */
471 struct vnode *tdp; /* saved dp */
472 struct mount *mp; /* mount table entry */
474 int docache; /* == 0 do not cache last component */
475 int wantparent; /* 1 => wantparent or lockparent flag */
476 int rdonly; /* lookup read-only flag bit */
478 int dpunlocked = 0; /* dp has already been unlocked */
479 struct componentname *cnp = &ndp->ni_cnd;
484 * Setup: break out flag bits into variables.
487 wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT);
488 KASSERT(cnp->cn_nameiop == LOOKUP || wantparent,
489 ("CREATE, DELETE, RENAME require LOCKPARENT or WANTPARENT."));
490 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE;
491 if (cnp->cn_nameiop == DELETE ||
492 (wantparent && cnp->cn_nameiop != CREATE &&
493 cnp->cn_nameiop != LOOKUP))
495 rdonly = cnp->cn_flags & RDONLY;
496 cnp->cn_flags &= ~ISSYMLINK;
499 * We use shared locks until we hit the parent of the last cn then
500 * we adjust based on the requesting flags.
503 cnp->cn_lkflags = LK_SHARED;
505 cnp->cn_lkflags = LK_EXCLUSIVE;
506 dp = ndp->ni_startdir;
507 ndp->ni_startdir = NULLVP;
509 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | LK_RETRY,
514 * Search a new directory.
516 * The last component of the filename is left accessible via
517 * cnp->cn_nameptr for callers that need the name. Callers needing
518 * the name set the SAVENAME flag. When done, they assume
519 * responsibility for freeing the pathname buffer.
522 for (cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++)
524 cnp->cn_namelen = cp - cnp->cn_nameptr;
525 if (cnp->cn_namelen > NAME_MAX) {
526 error = ENAMETOOLONG;
529 #ifdef NAMEI_DIAGNOSTIC
532 printf("{%s}: ", cnp->cn_nameptr);
535 ndp->ni_pathlen -= cnp->cn_namelen;
539 * Replace multiple slashes by a single slash and trailing slashes
540 * by a null. This must be done before VOP_LOOKUP() because some
541 * fs's don't know about trailing slashes. Remember if there were
542 * trailing slashes to handle symlinks, existing non-directories
543 * and non-existing files that won't be directories specially later.
545 while (*cp == '/' && (cp[1] == '/' || cp[1] == '\0')) {
549 *ndp->ni_next = '\0';
550 cnp->cn_flags |= TRAILINGSLASH;
555 cnp->cn_flags |= MAKEENTRY;
556 if (*cp == '\0' && docache == 0)
557 cnp->cn_flags &= ~MAKEENTRY;
558 if (cnp->cn_namelen == 2 &&
559 cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.')
560 cnp->cn_flags |= ISDOTDOT;
562 cnp->cn_flags &= ~ISDOTDOT;
563 if (*ndp->ni_next == 0)
564 cnp->cn_flags |= ISLASTCN;
566 cnp->cn_flags &= ~ISLASTCN;
568 if ((cnp->cn_flags & ISLASTCN) != 0 &&
569 cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.' &&
570 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
576 * Check for degenerate name (e.g. / or "")
577 * which is a way of talking about a directory,
578 * e.g. like "/." or ".".
580 if (cnp->cn_nameptr[0] == '\0') {
581 if (dp->v_type != VDIR) {
585 if (cnp->cn_nameiop != LOOKUP) {
595 if (cnp->cn_flags & AUDITVNODE1)
596 AUDIT_ARG_VNODE1(dp);
597 else if (cnp->cn_flags & AUDITVNODE2)
598 AUDIT_ARG_VNODE2(dp);
600 if (!(cnp->cn_flags & (LOCKPARENT | LOCKLEAF)))
602 /* XXX This should probably move to the top of function. */
603 if (cnp->cn_flags & SAVESTART)
604 panic("lookup: SAVESTART");
609 * Handle "..": five special cases.
610 * 0. If doing a capability lookup, return ENOTCAPABLE (this is a
611 * fairly conservative design choice, but it's the only one that we
612 * are satisfied guarantees the property we're looking for).
613 * 1. Return an error if this is the last component of
614 * the name and the operation is DELETE or RENAME.
615 * 2. If at root directory (e.g. after chroot)
616 * or at absolute root directory
617 * then ignore it so can't get out.
618 * 3. If this vnode is the root of a mounted
619 * filesystem, then replace it with the
620 * vnode which was mounted on so we take the
621 * .. in the other filesystem.
622 * 4. If the vnode is the top directory of
623 * the jail or chroot, don't let them out.
625 if (cnp->cn_flags & ISDOTDOT) {
626 if (ndp->ni_strictrelative != 0) {
628 if (KTRPOINT(curthread, KTR_CAPFAIL))
629 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
634 if ((cnp->cn_flags & ISLASTCN) != 0 &&
635 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
640 for (pr = cnp->cn_cred->cr_prison; pr != NULL;
642 if (dp == pr->pr_root)
644 if (dp == ndp->ni_rootdir ||
645 dp == ndp->ni_topdir ||
648 ((dp->v_vflag & VV_ROOT) != 0 &&
649 (cnp->cn_flags & NOCROSSMOUNT) != 0)) {
655 if ((dp->v_vflag & VV_ROOT) == 0)
657 if (dp->v_iflag & VI_DOOMED) { /* forced unmount */
662 dp = dp->v_mount->mnt_vnodecovered;
666 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags |
667 LK_RETRY, ISDOTDOT));
672 * We now have a segment name to search for, and a directory to search.
676 if ((cnp->cn_flags & NOMACCHECK) == 0) {
677 error = mac_vnode_check_lookup(cnp->cn_thread->td_ucred, dp,
685 ASSERT_VOP_LOCKED(dp, "lookup");
687 * If we have a shared lock we may need to upgrade the lock for the
690 if (dp != vp_crossmp &&
691 VOP_ISLOCKED(dp) == LK_SHARED &&
692 (cnp->cn_flags & ISLASTCN) && (cnp->cn_flags & LOCKPARENT))
693 vn_lock(dp, LK_UPGRADE|LK_RETRY);
694 if ((dp->v_iflag & VI_DOOMED) != 0) {
699 * If we're looking up the last component and we need an exclusive
700 * lock, adjust our lkflags.
702 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags))
703 cnp->cn_lkflags = LK_EXCLUSIVE;
704 #ifdef NAMEI_DIAGNOSTIC
705 vprint("lookup in", dp);
707 lkflags_save = cnp->cn_lkflags;
708 cnp->cn_lkflags = compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags,
710 if ((error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp)) != 0) {
711 cnp->cn_lkflags = lkflags_save;
712 KASSERT(ndp->ni_vp == NULL, ("leaf should be empty"));
713 #ifdef NAMEI_DIAGNOSTIC
714 printf("not found\n");
716 if ((error == ENOENT) &&
717 (dp->v_vflag & VV_ROOT) && (dp->v_mount != NULL) &&
718 (dp->v_mount->mnt_flag & MNT_UNION)) {
720 dp = dp->v_mount->mnt_vnodecovered;
724 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags |
725 LK_RETRY, cnp->cn_flags));
729 if (error != EJUSTRETURN)
732 * At this point, we know we're at the end of the
733 * pathname. If creating / renaming, we can consider
734 * allowing the file or directory to be created / renamed,
735 * provided we're not on a read-only filesystem.
741 /* trailing slash only allowed for directories */
742 if ((cnp->cn_flags & TRAILINGSLASH) &&
743 !(cnp->cn_flags & WILLBEDIR)) {
747 if ((cnp->cn_flags & LOCKPARENT) == 0)
750 * We return with ni_vp NULL to indicate that the entry
751 * doesn't currently exist, leaving a pointer to the
752 * (possibly locked) directory vnode in ndp->ni_dvp.
754 if (cnp->cn_flags & SAVESTART) {
755 ndp->ni_startdir = ndp->ni_dvp;
756 VREF(ndp->ni_startdir);
760 cnp->cn_lkflags = lkflags_save;
761 #ifdef NAMEI_DIAGNOSTIC
765 * Take into account any additional components consumed by
766 * the underlying filesystem.
768 if (cnp->cn_consume > 0) {
769 cnp->cn_nameptr += cnp->cn_consume;
770 ndp->ni_next += cnp->cn_consume;
771 ndp->ni_pathlen -= cnp->cn_consume;
778 * Check to see if the vnode has been mounted on;
779 * if so find the root of the mounted filesystem.
781 while (dp->v_type == VDIR && (mp = dp->v_mountedhere) &&
782 (cnp->cn_flags & NOCROSSMOUNT) == 0) {
786 if (dp != ndp->ni_dvp)
791 ndp->ni_dvp = vp_crossmp;
792 error = VFS_ROOT(mp, compute_cn_lkflags(mp, cnp->cn_lkflags,
793 cnp->cn_flags), &tdp);
795 if (vn_lock(vp_crossmp, LK_SHARED | LK_NOWAIT))
796 panic("vp_crossmp exclusively locked or reclaimed");
801 ndp->ni_vp = dp = tdp;
805 * Check for symbolic link
807 if ((dp->v_type == VLNK) &&
808 ((cnp->cn_flags & FOLLOW) || (cnp->cn_flags & TRAILINGSLASH) ||
809 *ndp->ni_next == '/')) {
810 cnp->cn_flags |= ISSYMLINK;
811 if (dp->v_iflag & VI_DOOMED) {
813 * We can't know whether the directory was mounted with
814 * NOSYMFOLLOW, so we can't follow safely.
819 if (dp->v_mount->mnt_flag & MNT_NOSYMFOLLOW) {
824 * Symlink code always expects an unlocked dvp.
826 if (ndp->ni_dvp != ndp->ni_vp) {
827 VOP_UNLOCK(ndp->ni_dvp, 0);
835 * Not a symbolic link that we will follow. Continue with the
836 * next component if there is any; otherwise, we're done.
838 KASSERT((cnp->cn_flags & ISLASTCN) || *ndp->ni_next == '/',
839 ("lookup: invalid path state."));
840 if (*ndp->ni_next == '/') {
841 cnp->cn_nameptr = ndp->ni_next;
842 while (*cnp->cn_nameptr == '/') {
846 if (ndp->ni_dvp != dp)
853 * If we're processing a path with a trailing slash,
854 * check that the end result is a directory.
856 if ((cnp->cn_flags & TRAILINGSLASH) && dp->v_type != VDIR) {
861 * Disallow directory write attempts on read-only filesystems.
864 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
868 if (cnp->cn_flags & SAVESTART) {
869 ndp->ni_startdir = ndp->ni_dvp;
870 VREF(ndp->ni_startdir);
874 if (ndp->ni_dvp != dp)
878 } else if ((cnp->cn_flags & LOCKPARENT) == 0 && ndp->ni_dvp != dp) {
879 VOP_UNLOCK(ndp->ni_dvp, 0);
883 if (cnp->cn_flags & AUDITVNODE1)
884 AUDIT_ARG_VNODE1(dp);
885 else if (cnp->cn_flags & AUDITVNODE2)
886 AUDIT_ARG_VNODE2(dp);
888 if ((cnp->cn_flags & LOCKLEAF) == 0)
892 * Because of lookup_shared we may have the vnode shared locked, but
893 * the caller may want it to be exclusively locked.
895 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags) &&
896 VOP_ISLOCKED(dp) != LK_EXCLUSIVE) {
897 vn_lock(dp, LK_UPGRADE | LK_RETRY);
898 if (dp->v_iflag & VI_DOOMED) {
906 if (ni_dvp_unlocked != 2) {
907 if (dp != ndp->ni_dvp && !ni_dvp_unlocked)
920 * relookup - lookup a path name component
921 * Used by lookup to re-acquire things.
924 relookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp)
926 struct vnode *dp = 0; /* the directory we are searching */
927 int wantparent; /* 1 => wantparent or lockparent flag */
928 int rdonly; /* lookup read-only flag bit */
931 KASSERT(cnp->cn_flags & ISLASTCN,
932 ("relookup: Not given last component."));
934 * Setup: break out flag bits into variables.
936 wantparent = cnp->cn_flags & (LOCKPARENT|WANTPARENT);
937 KASSERT(wantparent, ("relookup: parent not wanted."));
938 rdonly = cnp->cn_flags & RDONLY;
939 cnp->cn_flags &= ~ISSYMLINK;
941 cnp->cn_lkflags = LK_EXCLUSIVE;
942 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY);
945 * Search a new directory.
947 * The last component of the filename is left accessible via
948 * cnp->cn_nameptr for callers that need the name. Callers needing
949 * the name set the SAVENAME flag. When done, they assume
950 * responsibility for freeing the pathname buffer.
952 #ifdef NAMEI_DIAGNOSTIC
953 printf("{%s}: ", cnp->cn_nameptr);
957 * Check for "" which represents the root directory after slash
960 if (cnp->cn_nameptr[0] == '\0') {
962 * Support only LOOKUP for "/" because lookup()
963 * can't succeed for CREATE, DELETE and RENAME.
965 KASSERT(cnp->cn_nameiop == LOOKUP, ("nameiop must be LOOKUP"));
966 KASSERT(dp->v_type == VDIR, ("dp is not a directory"));
968 if (!(cnp->cn_flags & LOCKLEAF))
971 /* XXX This should probably move to the top of function. */
972 if (cnp->cn_flags & SAVESTART)
973 panic("lookup: SAVESTART");
977 if (cnp->cn_flags & ISDOTDOT)
978 panic ("relookup: lookup on dot-dot");
981 * We now have a segment name to search for, and a directory to search.
983 #ifdef NAMEI_DIAGNOSTIC
984 vprint("search in:", dp);
986 if ((error = VOP_LOOKUP(dp, vpp, cnp)) != 0) {
987 KASSERT(*vpp == NULL, ("leaf should be empty"));
988 if (error != EJUSTRETURN)
991 * If creating and at end of pathname, then can consider
992 * allowing file to be created.
998 /* ASSERT(dvp == ndp->ni_startdir) */
999 if (cnp->cn_flags & SAVESTART)
1001 if ((cnp->cn_flags & LOCKPARENT) == 0)
1004 * We return with ni_vp NULL to indicate that the entry
1005 * doesn't currently exist, leaving a pointer to the
1006 * (possibly locked) directory vnode in ndp->ni_dvp.
1014 * Disallow directory write attempts on read-only filesystems.
1017 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
1026 * Set the parent lock/ref state to the requested state.
1028 if ((cnp->cn_flags & LOCKPARENT) == 0 && dvp != dp) {
1033 } else if (!wantparent)
1036 * Check for symbolic link
1038 KASSERT(dp->v_type != VLNK || !(cnp->cn_flags & FOLLOW),
1039 ("relookup: symlink found.\n"));
1041 /* ASSERT(dvp == ndp->ni_startdir) */
1042 if (cnp->cn_flags & SAVESTART)
1045 if ((cnp->cn_flags & LOCKLEAF) == 0)
1055 NDINIT_ALL(struct nameidata *ndp, u_long op, u_long flags, enum uio_seg segflg,
1056 const char *namep, int dirfd, struct vnode *startdir, cap_rights_t *rightsp,
1060 ndp->ni_cnd.cn_nameiop = op;
1061 ndp->ni_cnd.cn_flags = flags;
1062 ndp->ni_segflg = segflg;
1063 ndp->ni_dirp = namep;
1064 ndp->ni_dirfd = dirfd;
1065 ndp->ni_startdir = startdir;
1066 ndp->ni_strictrelative = 0;
1067 if (rightsp != NULL)
1068 ndp->ni_rightsneeded = *rightsp;
1070 cap_rights_init(&ndp->ni_rightsneeded);
1071 filecaps_init(&ndp->ni_filecaps);
1072 ndp->ni_cnd.cn_thread = td;
1076 * Free data allocated by namei(); see namei(9) for details.
1079 NDFREE(struct nameidata *ndp, const u_int flags)
1087 if (!(flags & NDF_NO_FREE_PNBUF) &&
1088 (ndp->ni_cnd.cn_flags & HASBUF)) {
1089 uma_zfree(namei_zone, ndp->ni_cnd.cn_pnbuf);
1090 ndp->ni_cnd.cn_flags &= ~HASBUF;
1092 if (!(flags & NDF_NO_VP_UNLOCK) &&
1093 (ndp->ni_cnd.cn_flags & LOCKLEAF) && ndp->ni_vp)
1095 if (!(flags & NDF_NO_VP_RELE) && ndp->ni_vp) {
1104 VOP_UNLOCK(ndp->ni_vp, 0);
1105 if (!(flags & NDF_NO_DVP_UNLOCK) &&
1106 (ndp->ni_cnd.cn_flags & LOCKPARENT) &&
1107 ndp->ni_dvp != ndp->ni_vp)
1109 if (!(flags & NDF_NO_DVP_RELE) &&
1110 (ndp->ni_cnd.cn_flags & (LOCKPARENT|WANTPARENT))) {
1119 VOP_UNLOCK(ndp->ni_dvp, 0);
1120 if (!(flags & NDF_NO_STARTDIR_RELE) &&
1121 (ndp->ni_cnd.cn_flags & SAVESTART)) {
1122 vrele(ndp->ni_startdir);
1123 ndp->ni_startdir = NULL;
1128 * Determine if there is a suitable alternate filename under the specified
1129 * prefix for the specified path. If the create flag is set, then the
1130 * alternate prefix will be used so long as the parent directory exists.
1131 * This is used by the various compatiblity ABIs so that Linux binaries prefer
1132 * files under /compat/linux for example. The chosen path (whether under
1133 * the prefix or under /) is returned in a kernel malloc'd buffer pointed
1134 * to by pathbuf. The caller is responsible for free'ing the buffer from
1135 * the M_TEMP bucket if one is returned.
1138 kern_alternate_path(struct thread *td, const char *prefix, const char *path,
1139 enum uio_seg pathseg, char **pathbuf, int create, int dirfd)
1141 struct nameidata nd, ndroot;
1142 char *ptr, *buf, *cp;
1146 buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
1149 /* Copy the prefix into the new pathname as a starting point. */
1150 len = strlcpy(buf, prefix, MAXPATHLEN);
1151 if (len >= MAXPATHLEN) {
1156 sz = MAXPATHLEN - len;
1159 /* Append the filename to the prefix. */
1160 if (pathseg == UIO_SYSSPACE)
1161 error = copystr(path, ptr, sz, &len);
1163 error = copyinstr(path, ptr, sz, &len);
1171 /* Only use a prefix with absolute pathnames. */
1177 if (dirfd != AT_FDCWD) {
1179 * We want the original because the "prefix" is
1180 * included in the already opened dirfd.
1182 bcopy(ptr, buf, len);
1187 * We know that there is a / somewhere in this pathname.
1188 * Search backwards for it, to find the file's parent dir
1189 * to see if it exists in the alternate tree. If it does,
1190 * and we want to create a file (cflag is set). We don't
1191 * need to worry about the root comparison in this case.
1195 for (cp = &ptr[len] - 1; *cp != '/'; cp--);
1198 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, td);
1204 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, td);
1211 * We now compare the vnode of the prefix to the one
1212 * vnode asked. If they resolve to be the same, then we
1213 * ignore the match so that the real root gets used.
1214 * This avoids the problem of traversing "../.." to find the
1215 * root directory and never finding it, because "/" resolves
1216 * to the emulation root directory. This is expensive :-(
1218 NDINIT(&ndroot, LOOKUP, FOLLOW, UIO_SYSSPACE, prefix,
1221 /* We shouldn't ever get an error from this namei(). */
1222 error = namei(&ndroot);
1224 if (nd.ni_vp == ndroot.ni_vp)
1227 NDFREE(&ndroot, NDF_ONLY_PNBUF);
1228 vrele(ndroot.ni_vp);
1232 NDFREE(&nd, NDF_ONLY_PNBUF);
1236 /* If there was an error, use the original path name. */
1238 bcopy(ptr, buf, len);