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.
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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(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;
137 ndp->ni_cnd.cn_cred = ndp->ni_cnd.cn_thread->td_ucred;
138 KASSERT(cnp->cn_cred && p, ("namei: bad cred/proc"));
139 KASSERT((cnp->cn_nameiop & (~OPMASK)) == 0,
140 ("namei: nameiop contaminated with flags"));
141 KASSERT((cnp->cn_flags & OPMASK) == 0,
142 ("namei: flags contaminated with nameiops"));
144 cnp->cn_flags &= ~LOCKSHARED;
147 /* We will set this ourselves if we need it. */
148 cnp->cn_flags &= ~TRAILINGSLASH;
151 * Get a buffer for the name to be translated, and copy the
152 * name into the buffer.
154 if ((cnp->cn_flags & HASBUF) == 0)
155 cnp->cn_pnbuf = uma_zalloc(namei_zone, M_WAITOK);
156 if (ndp->ni_segflg == UIO_SYSSPACE)
157 error = copystr(ndp->ni_dirp, cnp->cn_pnbuf,
158 MAXPATHLEN, (size_t *)&ndp->ni_pathlen);
160 error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf,
161 MAXPATHLEN, (size_t *)&ndp->ni_pathlen);
164 * Don't allow empty pathnames.
166 if (!error && *cnp->cn_pnbuf == '\0')
169 #ifdef CAPABILITY_MODE
171 * In capability mode, lookups must be "strictly relative" (i.e.
172 * not an absolute path, and not containing '..' components) to
173 * a real file descriptor, not the pseudo-descriptor AT_FDCWD.
175 if (error == 0 && IN_CAPABILITY_MODE(td) &&
176 (cnp->cn_flags & NOCAPCHECK) == 0) {
177 ndp->ni_strictrelative = 1;
178 if (ndp->ni_dirfd == AT_FDCWD) {
180 if (KTRPOINT(td, KTR_CAPFAIL))
181 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
188 uma_zfree(namei_zone, cnp->cn_pnbuf);
190 cnp->cn_pnbuf = NULL;
191 cnp->cn_nameptr = NULL;
198 if (KTRPOINT(td, KTR_NAMEI)) {
199 KASSERT(cnp->cn_thread == curthread,
200 ("namei not using curthread"));
201 ktrnamei(cnp->cn_pnbuf);
205 * Get starting point for the translation.
208 ndp->ni_rootdir = fdp->fd_rdir;
209 ndp->ni_topdir = fdp->fd_jdir;
212 * If we are auditing the kernel pathname, save the user pathname.
214 if (cnp->cn_flags & AUDITVNODE1)
215 AUDIT_ARG_UPATH1(td, ndp->ni_dirfd, cnp->cn_pnbuf);
216 if (cnp->cn_flags & AUDITVNODE2)
217 AUDIT_ARG_UPATH2(td, ndp->ni_dirfd, cnp->cn_pnbuf);
220 if (cnp->cn_pnbuf[0] != '/') {
221 if (ndp->ni_startdir != NULL) {
222 dp = ndp->ni_startdir;
224 } else if (ndp->ni_dirfd != AT_FDCWD) {
227 rights = ndp->ni_rightsneeded;
228 cap_rights_set(&rights, CAP_LOOKUP);
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 &rights, &ndp->ni_filecaps, &dp);
238 * If file descriptor doesn't have all rights,
239 * all lookups relative to it must also be
243 if (!cap_rights_contains(&ndp->ni_filecaps.fc_rights,
245 ndp->ni_filecaps.fc_fcntls != CAP_FCNTL_ALL ||
246 ndp->ni_filecaps.fc_nioctls != -1) {
247 ndp->ni_strictrelative = 1;
251 if (error != 0 || dp != NULL) {
252 FILEDESC_SUNLOCK(fdp);
253 if (error == 0 && dp->v_type != VDIR) {
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 vrele(ndp->ni_startdir);
274 SDT_PROBE(vfs, namei, lookup, entry, dp, cnp->cn_pnbuf,
275 cnp->cn_flags, 0, 0);
278 * Check if root directory should replace current directory.
279 * Done at start of translation and after symbolic link.
281 cnp->cn_nameptr = cnp->cn_pnbuf;
282 if (*(cnp->cn_nameptr) == '/') {
284 if (ndp->ni_strictrelative != 0) {
286 if (KTRPOINT(curthread, KTR_CAPFAIL))
287 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
289 return (ENOTCAPABLE);
291 while (*(cnp->cn_nameptr) == '/') {
295 dp = ndp->ni_rootdir;
298 ndp->ni_startdir = dp;
301 uma_zfree(namei_zone, cnp->cn_pnbuf);
303 cnp->cn_pnbuf = NULL;
304 cnp->cn_nameptr = NULL;
306 SDT_PROBE(vfs, namei, lookup, return, error, NULL, 0,
311 * If not a symbolic link, we're done.
313 if ((cnp->cn_flags & ISSYMLINK) == 0) {
314 if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) {
315 uma_zfree(namei_zone, cnp->cn_pnbuf);
317 cnp->cn_pnbuf = NULL;
318 cnp->cn_nameptr = NULL;
321 cnp->cn_flags |= HASBUF;
323 SDT_PROBE(vfs, namei, lookup, return, 0, ndp->ni_vp,
327 if (ndp->ni_loopcnt++ >= MAXSYMLINKS) {
332 if ((cnp->cn_flags & NOMACCHECK) == 0) {
333 error = mac_vnode_check_readlink(td->td_ucred,
339 if (ndp->ni_pathlen > 1)
340 cp = uma_zalloc(namei_zone, M_WAITOK);
344 aiov.iov_len = MAXPATHLEN;
345 auio.uio_iov = &aiov;
348 auio.uio_rw = UIO_READ;
349 auio.uio_segflg = UIO_SYSSPACE;
351 auio.uio_resid = MAXPATHLEN;
352 error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred);
354 if (ndp->ni_pathlen > 1)
355 uma_zfree(namei_zone, cp);
358 linklen = MAXPATHLEN - auio.uio_resid;
360 if (ndp->ni_pathlen > 1)
361 uma_zfree(namei_zone, cp);
365 if (linklen + ndp->ni_pathlen >= MAXPATHLEN) {
366 if (ndp->ni_pathlen > 1)
367 uma_zfree(namei_zone, cp);
368 error = ENAMETOOLONG;
371 if (ndp->ni_pathlen > 1) {
372 bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen);
373 uma_zfree(namei_zone, cnp->cn_pnbuf);
376 cnp->cn_pnbuf[linklen] = '\0';
377 ndp->ni_pathlen += linklen;
381 uma_zfree(namei_zone, cnp->cn_pnbuf);
383 cnp->cn_pnbuf = NULL;
384 cnp->cn_nameptr = NULL;
389 SDT_PROBE(vfs, namei, lookup, return, error, NULL, 0, 0, 0);
394 compute_cn_lkflags(struct mount *mp, int lkflags, int cnflags)
397 if (mp == NULL || ((lkflags & LK_SHARED) &&
398 (!(mp->mnt_kern_flag & MNTK_LOOKUP_SHARED) ||
399 ((cnflags & ISDOTDOT) &&
400 (mp->mnt_kern_flag & MNTK_LOOKUP_EXCL_DOTDOT))))) {
401 lkflags &= ~LK_SHARED;
402 lkflags |= LK_EXCLUSIVE;
408 needs_exclusive_leaf(struct mount *mp, int flags)
412 * Intermediate nodes can use shared locks, we only need to
413 * force an exclusive lock for leaf nodes.
415 if ((flags & (ISLASTCN | LOCKLEAF)) != (ISLASTCN | LOCKLEAF))
418 /* Always use exclusive locks if LOCKSHARED isn't set. */
419 if (!(flags & LOCKSHARED))
423 * For lookups during open(), if the mount point supports
424 * extended shared operations, then use a shared lock for the
425 * leaf node, otherwise use an exclusive lock.
427 if ((flags & ISOPEN) != 0)
428 return (!MNT_EXTENDED_SHARED(mp));
431 * Lookup requests outside of open() that specify LOCKSHARED
432 * only need a shared lock on the leaf vnode.
439 * This is a very central and rather complicated routine.
441 * The pathname is pointed to by ni_ptr and is of length ni_pathlen.
442 * The starting directory is taken from ni_startdir. The pathname is
443 * descended until done, or a symbolic link is encountered. The variable
444 * ni_more is clear if the path is completed; it is set to one if a
445 * symbolic link needing interpretation is encountered.
447 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on
448 * whether the name is to be looked up, created, renamed, or deleted.
449 * When CREATE, RENAME, or DELETE is specified, information usable in
450 * creating, renaming, or deleting a directory entry may be calculated.
451 * If flag has LOCKPARENT or'ed into it, the parent directory is returned
452 * locked. If flag has WANTPARENT or'ed into it, the parent directory is
453 * returned unlocked. Otherwise the parent directory is not returned. If
454 * the target of the pathname exists and LOCKLEAF is or'ed into the flag
455 * the target is returned locked, otherwise it is returned unlocked.
456 * When creating or renaming and LOCKPARENT is specified, the target may not
457 * be ".". When deleting and LOCKPARENT is specified, the target may be ".".
459 * Overall outline of lookup:
462 * identify next component of name at ndp->ni_ptr
463 * handle degenerate case where name is null string
464 * if .. and crossing mount points and on mounted filesys, find parent
465 * call VOP_LOOKUP routine for next component name
466 * directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set
467 * component vnode returned in ni_vp (if it exists), locked.
468 * if result vnode is mounted on and crossing mount points,
469 * find mounted on vnode
470 * if more components of name, do next level at dirloop
471 * return the answer in ni_vp, locked if LOCKLEAF set
472 * if LOCKPARENT set, return locked parent in ni_dvp
473 * if WANTPARENT set, return unlocked parent in ni_dvp
476 lookup(struct nameidata *ndp)
478 char *cp; /* pointer into pathname argument */
479 struct vnode *dp = 0; /* the directory we are searching */
480 struct vnode *tdp; /* saved dp */
481 struct mount *mp; /* mount table entry */
483 int docache; /* == 0 do not cache last component */
484 int wantparent; /* 1 => wantparent or lockparent flag */
485 int rdonly; /* lookup read-only flag bit */
487 int dpunlocked = 0; /* dp has already been unlocked */
488 struct componentname *cnp = &ndp->ni_cnd;
493 * Setup: break out flag bits into variables.
496 wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT);
497 KASSERT(cnp->cn_nameiop == LOOKUP || wantparent,
498 ("CREATE, DELETE, RENAME require LOCKPARENT or WANTPARENT."));
499 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE;
500 if (cnp->cn_nameiop == DELETE ||
501 (wantparent && cnp->cn_nameiop != CREATE &&
502 cnp->cn_nameiop != LOOKUP))
504 rdonly = cnp->cn_flags & RDONLY;
505 cnp->cn_flags &= ~ISSYMLINK;
508 * We use shared locks until we hit the parent of the last cn then
509 * we adjust based on the requesting flags.
512 cnp->cn_lkflags = LK_SHARED;
514 cnp->cn_lkflags = LK_EXCLUSIVE;
515 dp = ndp->ni_startdir;
516 ndp->ni_startdir = NULLVP;
518 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | LK_RETRY,
523 * Search a new directory.
525 * The last component of the filename is left accessible via
526 * cnp->cn_nameptr for callers that need the name. Callers needing
527 * the name set the SAVENAME flag. When done, they assume
528 * responsibility for freeing the pathname buffer.
531 for (cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++)
533 cnp->cn_namelen = cp - cnp->cn_nameptr;
534 if (cnp->cn_namelen > NAME_MAX) {
535 error = ENAMETOOLONG;
538 #ifdef NAMEI_DIAGNOSTIC
541 printf("{%s}: ", cnp->cn_nameptr);
544 ndp->ni_pathlen -= cnp->cn_namelen;
548 * Replace multiple slashes by a single slash and trailing slashes
549 * by a null. This must be done before VOP_LOOKUP() because some
550 * fs's don't know about trailing slashes. Remember if there were
551 * trailing slashes to handle symlinks, existing non-directories
552 * and non-existing files that won't be directories specially later.
554 while (*cp == '/' && (cp[1] == '/' || cp[1] == '\0')) {
558 *ndp->ni_next = '\0';
559 cnp->cn_flags |= TRAILINGSLASH;
564 cnp->cn_flags |= MAKEENTRY;
565 if (*cp == '\0' && docache == 0)
566 cnp->cn_flags &= ~MAKEENTRY;
567 if (cnp->cn_namelen == 2 &&
568 cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.')
569 cnp->cn_flags |= ISDOTDOT;
571 cnp->cn_flags &= ~ISDOTDOT;
572 if (*ndp->ni_next == 0)
573 cnp->cn_flags |= ISLASTCN;
575 cnp->cn_flags &= ~ISLASTCN;
577 if ((cnp->cn_flags & ISLASTCN) != 0 &&
578 cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.' &&
579 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
585 * Check for degenerate name (e.g. / or "")
586 * which is a way of talking about a directory,
587 * e.g. like "/." or ".".
589 if (cnp->cn_nameptr[0] == '\0') {
590 if (dp->v_type != VDIR) {
594 if (cnp->cn_nameiop != LOOKUP) {
604 if (cnp->cn_flags & AUDITVNODE1)
605 AUDIT_ARG_VNODE1(dp);
606 else if (cnp->cn_flags & AUDITVNODE2)
607 AUDIT_ARG_VNODE2(dp);
609 if (!(cnp->cn_flags & (LOCKPARENT | LOCKLEAF)))
611 /* XXX This should probably move to the top of function. */
612 if (cnp->cn_flags & SAVESTART)
613 panic("lookup: SAVESTART");
618 * Handle "..": five special cases.
619 * 0. If doing a capability lookup, return ENOTCAPABLE (this is a
620 * fairly conservative design choice, but it's the only one that we
621 * are satisfied guarantees the property we're looking for).
622 * 1. Return an error if this is the last component of
623 * the name and the operation is DELETE or RENAME.
624 * 2. If at root directory (e.g. after chroot)
625 * or at absolute root directory
626 * then ignore it so can't get out.
627 * 3. If this vnode is the root of a mounted
628 * filesystem, then replace it with the
629 * vnode which was mounted on so we take the
630 * .. in the other filesystem.
631 * 4. If the vnode is the top directory of
632 * the jail or chroot, don't let them out.
634 if (cnp->cn_flags & ISDOTDOT) {
635 if (ndp->ni_strictrelative != 0) {
637 if (KTRPOINT(curthread, KTR_CAPFAIL))
638 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
643 if ((cnp->cn_flags & ISLASTCN) != 0 &&
644 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
649 for (pr = cnp->cn_cred->cr_prison; pr != NULL;
651 if (dp == pr->pr_root)
653 if (dp == ndp->ni_rootdir ||
654 dp == ndp->ni_topdir ||
657 ((dp->v_vflag & VV_ROOT) != 0 &&
658 (cnp->cn_flags & NOCROSSMOUNT) != 0)) {
664 if ((dp->v_vflag & VV_ROOT) == 0)
666 if (dp->v_iflag & VI_DOOMED) { /* forced unmount */
671 dp = dp->v_mount->mnt_vnodecovered;
675 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags |
676 LK_RETRY, ISDOTDOT));
681 * We now have a segment name to search for, and a directory to search.
685 if ((cnp->cn_flags & NOMACCHECK) == 0) {
686 error = mac_vnode_check_lookup(cnp->cn_thread->td_ucred, dp,
694 ASSERT_VOP_LOCKED(dp, "lookup");
696 * If we have a shared lock we may need to upgrade the lock for the
699 if (dp != vp_crossmp &&
700 VOP_ISLOCKED(dp) == LK_SHARED &&
701 (cnp->cn_flags & ISLASTCN) && (cnp->cn_flags & LOCKPARENT))
702 vn_lock(dp, LK_UPGRADE|LK_RETRY);
703 if ((dp->v_iflag & VI_DOOMED) != 0) {
708 * If we're looking up the last component and we need an exclusive
709 * lock, adjust our lkflags.
711 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags))
712 cnp->cn_lkflags = LK_EXCLUSIVE;
713 #ifdef NAMEI_DIAGNOSTIC
714 vprint("lookup in", dp);
716 lkflags_save = cnp->cn_lkflags;
717 cnp->cn_lkflags = compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags,
719 if ((error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp)) != 0) {
720 cnp->cn_lkflags = lkflags_save;
721 KASSERT(ndp->ni_vp == NULL, ("leaf should be empty"));
722 #ifdef NAMEI_DIAGNOSTIC
723 printf("not found\n");
725 if ((error == ENOENT) &&
726 (dp->v_vflag & VV_ROOT) && (dp->v_mount != NULL) &&
727 (dp->v_mount->mnt_flag & MNT_UNION)) {
729 dp = dp->v_mount->mnt_vnodecovered;
733 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags |
734 LK_RETRY, cnp->cn_flags));
738 if (error != EJUSTRETURN)
741 * At this point, we know we're at the end of the
742 * pathname. If creating / renaming, we can consider
743 * allowing the file or directory to be created / renamed,
744 * provided we're not on a read-only filesystem.
750 /* trailing slash only allowed for directories */
751 if ((cnp->cn_flags & TRAILINGSLASH) &&
752 !(cnp->cn_flags & WILLBEDIR)) {
756 if ((cnp->cn_flags & LOCKPARENT) == 0)
759 * We return with ni_vp NULL to indicate that the entry
760 * doesn't currently exist, leaving a pointer to the
761 * (possibly locked) directory vnode in ndp->ni_dvp.
763 if (cnp->cn_flags & SAVESTART) {
764 ndp->ni_startdir = ndp->ni_dvp;
765 VREF(ndp->ni_startdir);
769 cnp->cn_lkflags = lkflags_save;
770 #ifdef NAMEI_DIAGNOSTIC
774 * Take into account any additional components consumed by
775 * the underlying filesystem.
777 if (cnp->cn_consume > 0) {
778 cnp->cn_nameptr += cnp->cn_consume;
779 ndp->ni_next += cnp->cn_consume;
780 ndp->ni_pathlen -= cnp->cn_consume;
787 * Check to see if the vnode has been mounted on;
788 * if so find the root of the mounted filesystem.
790 while (dp->v_type == VDIR && (mp = dp->v_mountedhere) &&
791 (cnp->cn_flags & NOCROSSMOUNT) == 0) {
795 if (dp != ndp->ni_dvp)
800 ndp->ni_dvp = vp_crossmp;
801 error = VFS_ROOT(mp, compute_cn_lkflags(mp, cnp->cn_lkflags,
802 cnp->cn_flags), &tdp);
804 if (vn_lock(vp_crossmp, LK_SHARED | LK_NOWAIT))
805 panic("vp_crossmp exclusively locked or reclaimed");
810 ndp->ni_vp = dp = tdp;
814 * Check for symbolic link
816 if ((dp->v_type == VLNK) &&
817 ((cnp->cn_flags & FOLLOW) || (cnp->cn_flags & TRAILINGSLASH) ||
818 *ndp->ni_next == '/')) {
819 cnp->cn_flags |= ISSYMLINK;
820 if (dp->v_iflag & VI_DOOMED) {
822 * We can't know whether the directory was mounted with
823 * NOSYMFOLLOW, so we can't follow safely.
828 if (dp->v_mount->mnt_flag & MNT_NOSYMFOLLOW) {
833 * Symlink code always expects an unlocked dvp.
835 if (ndp->ni_dvp != ndp->ni_vp) {
836 VOP_UNLOCK(ndp->ni_dvp, 0);
844 * Not a symbolic link that we will follow. Continue with the
845 * next component if there is any; otherwise, we're done.
847 KASSERT((cnp->cn_flags & ISLASTCN) || *ndp->ni_next == '/',
848 ("lookup: invalid path state."));
849 if (*ndp->ni_next == '/') {
850 cnp->cn_nameptr = ndp->ni_next;
851 while (*cnp->cn_nameptr == '/') {
855 if (ndp->ni_dvp != dp)
862 * If we're processing a path with a trailing slash,
863 * check that the end result is a directory.
865 if ((cnp->cn_flags & TRAILINGSLASH) && dp->v_type != VDIR) {
870 * Disallow directory write attempts on read-only filesystems.
873 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
877 if (cnp->cn_flags & SAVESTART) {
878 ndp->ni_startdir = ndp->ni_dvp;
879 VREF(ndp->ni_startdir);
883 if (ndp->ni_dvp != dp)
887 } else if ((cnp->cn_flags & LOCKPARENT) == 0 && ndp->ni_dvp != dp) {
888 VOP_UNLOCK(ndp->ni_dvp, 0);
892 if (cnp->cn_flags & AUDITVNODE1)
893 AUDIT_ARG_VNODE1(dp);
894 else if (cnp->cn_flags & AUDITVNODE2)
895 AUDIT_ARG_VNODE2(dp);
897 if ((cnp->cn_flags & LOCKLEAF) == 0)
901 * Because of lookup_shared we may have the vnode shared locked, but
902 * the caller may want it to be exclusively locked.
904 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags) &&
905 VOP_ISLOCKED(dp) != LK_EXCLUSIVE) {
906 vn_lock(dp, LK_UPGRADE | LK_RETRY);
907 if (dp->v_iflag & VI_DOOMED) {
915 if (ni_dvp_unlocked != 2) {
916 if (dp != ndp->ni_dvp && !ni_dvp_unlocked)
929 * relookup - lookup a path name component
930 * Used by lookup to re-acquire things.
933 relookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp)
935 struct vnode *dp = 0; /* the directory we are searching */
936 int wantparent; /* 1 => wantparent or lockparent flag */
937 int rdonly; /* lookup read-only flag bit */
940 KASSERT(cnp->cn_flags & ISLASTCN,
941 ("relookup: Not given last component."));
943 * Setup: break out flag bits into variables.
945 wantparent = cnp->cn_flags & (LOCKPARENT|WANTPARENT);
946 KASSERT(wantparent, ("relookup: parent not wanted."));
947 rdonly = cnp->cn_flags & RDONLY;
948 cnp->cn_flags &= ~ISSYMLINK;
950 cnp->cn_lkflags = LK_EXCLUSIVE;
951 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY);
954 * Search a new directory.
956 * The last component of the filename is left accessible via
957 * cnp->cn_nameptr for callers that need the name. Callers needing
958 * the name set the SAVENAME flag. When done, they assume
959 * responsibility for freeing the pathname buffer.
961 #ifdef NAMEI_DIAGNOSTIC
962 printf("{%s}: ", cnp->cn_nameptr);
966 * Check for "" which represents the root directory after slash
969 if (cnp->cn_nameptr[0] == '\0') {
971 * Support only LOOKUP for "/" because lookup()
972 * can't succeed for CREATE, DELETE and RENAME.
974 KASSERT(cnp->cn_nameiop == LOOKUP, ("nameiop must be LOOKUP"));
975 KASSERT(dp->v_type == VDIR, ("dp is not a directory"));
977 if (!(cnp->cn_flags & LOCKLEAF))
980 /* XXX This should probably move to the top of function. */
981 if (cnp->cn_flags & SAVESTART)
982 panic("lookup: SAVESTART");
986 if (cnp->cn_flags & ISDOTDOT)
987 panic ("relookup: lookup on dot-dot");
990 * We now have a segment name to search for, and a directory to search.
992 #ifdef NAMEI_DIAGNOSTIC
993 vprint("search in:", dp);
995 if ((error = VOP_LOOKUP(dp, vpp, cnp)) != 0) {
996 KASSERT(*vpp == NULL, ("leaf should be empty"));
997 if (error != EJUSTRETURN)
1000 * If creating and at end of pathname, then can consider
1001 * allowing file to be created.
1007 /* ASSERT(dvp == ndp->ni_startdir) */
1008 if (cnp->cn_flags & SAVESTART)
1010 if ((cnp->cn_flags & LOCKPARENT) == 0)
1013 * We return with ni_vp NULL to indicate that the entry
1014 * doesn't currently exist, leaving a pointer to the
1015 * (possibly locked) directory vnode in ndp->ni_dvp.
1023 * Disallow directory write attempts on read-only filesystems.
1026 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
1035 * Set the parent lock/ref state to the requested state.
1037 if ((cnp->cn_flags & LOCKPARENT) == 0 && dvp != dp) {
1042 } else if (!wantparent)
1045 * Check for symbolic link
1047 KASSERT(dp->v_type != VLNK || !(cnp->cn_flags & FOLLOW),
1048 ("relookup: symlink found.\n"));
1050 /* ASSERT(dvp == ndp->ni_startdir) */
1051 if (cnp->cn_flags & SAVESTART)
1054 if ((cnp->cn_flags & LOCKLEAF) == 0)
1064 NDINIT_ALL(struct nameidata *ndp, u_long op, u_long flags, enum uio_seg segflg,
1065 const char *namep, int dirfd, struct vnode *startdir, cap_rights_t *rightsp,
1069 ndp->ni_cnd.cn_nameiop = op;
1070 ndp->ni_cnd.cn_flags = flags;
1071 ndp->ni_segflg = segflg;
1072 ndp->ni_dirp = namep;
1073 ndp->ni_dirfd = dirfd;
1074 ndp->ni_startdir = startdir;
1075 ndp->ni_strictrelative = 0;
1076 if (rightsp != NULL)
1077 ndp->ni_rightsneeded = *rightsp;
1079 cap_rights_init(&ndp->ni_rightsneeded);
1080 filecaps_init(&ndp->ni_filecaps);
1081 ndp->ni_cnd.cn_thread = td;
1085 * Free data allocated by namei(); see namei(9) for details.
1088 NDFREE(struct nameidata *ndp, const u_int flags)
1096 if (!(flags & NDF_NO_FREE_PNBUF) &&
1097 (ndp->ni_cnd.cn_flags & HASBUF)) {
1098 uma_zfree(namei_zone, ndp->ni_cnd.cn_pnbuf);
1099 ndp->ni_cnd.cn_flags &= ~HASBUF;
1101 if (!(flags & NDF_NO_VP_UNLOCK) &&
1102 (ndp->ni_cnd.cn_flags & LOCKLEAF) && ndp->ni_vp)
1104 if (!(flags & NDF_NO_VP_RELE) && ndp->ni_vp) {
1113 VOP_UNLOCK(ndp->ni_vp, 0);
1114 if (!(flags & NDF_NO_DVP_UNLOCK) &&
1115 (ndp->ni_cnd.cn_flags & LOCKPARENT) &&
1116 ndp->ni_dvp != ndp->ni_vp)
1118 if (!(flags & NDF_NO_DVP_RELE) &&
1119 (ndp->ni_cnd.cn_flags & (LOCKPARENT|WANTPARENT))) {
1128 VOP_UNLOCK(ndp->ni_dvp, 0);
1129 if (!(flags & NDF_NO_STARTDIR_RELE) &&
1130 (ndp->ni_cnd.cn_flags & SAVESTART)) {
1131 vrele(ndp->ni_startdir);
1132 ndp->ni_startdir = NULL;
1137 * Determine if there is a suitable alternate filename under the specified
1138 * prefix for the specified path. If the create flag is set, then the
1139 * alternate prefix will be used so long as the parent directory exists.
1140 * This is used by the various compatiblity ABIs so that Linux binaries prefer
1141 * files under /compat/linux for example. The chosen path (whether under
1142 * the prefix or under /) is returned in a kernel malloc'd buffer pointed
1143 * to by pathbuf. The caller is responsible for free'ing the buffer from
1144 * the M_TEMP bucket if one is returned.
1147 kern_alternate_path(struct thread *td, const char *prefix, const char *path,
1148 enum uio_seg pathseg, char **pathbuf, int create, int dirfd)
1150 struct nameidata nd, ndroot;
1151 char *ptr, *buf, *cp;
1155 buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
1158 /* Copy the prefix into the new pathname as a starting point. */
1159 len = strlcpy(buf, prefix, MAXPATHLEN);
1160 if (len >= MAXPATHLEN) {
1165 sz = MAXPATHLEN - len;
1168 /* Append the filename to the prefix. */
1169 if (pathseg == UIO_SYSSPACE)
1170 error = copystr(path, ptr, sz, &len);
1172 error = copyinstr(path, ptr, sz, &len);
1180 /* Only use a prefix with absolute pathnames. */
1186 if (dirfd != AT_FDCWD) {
1188 * We want the original because the "prefix" is
1189 * included in the already opened dirfd.
1191 bcopy(ptr, buf, len);
1196 * We know that there is a / somewhere in this pathname.
1197 * Search backwards for it, to find the file's parent dir
1198 * to see if it exists in the alternate tree. If it does,
1199 * and we want to create a file (cflag is set). We don't
1200 * need to worry about the root comparison in this case.
1204 for (cp = &ptr[len] - 1; *cp != '/'; cp--);
1207 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, td);
1213 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, td);
1220 * We now compare the vnode of the prefix to the one
1221 * vnode asked. If they resolve to be the same, then we
1222 * ignore the match so that the real root gets used.
1223 * This avoids the problem of traversing "../.." to find the
1224 * root directory and never finding it, because "/" resolves
1225 * to the emulation root directory. This is expensive :-(
1227 NDINIT(&ndroot, LOOKUP, FOLLOW, UIO_SYSSPACE, prefix,
1230 /* We shouldn't ever get an error from this namei(). */
1231 error = namei(&ndroot);
1233 if (nd.ni_vp == ndroot.ni_vp)
1236 NDFREE(&ndroot, NDF_ONLY_PNBUF);
1237 vrele(ndroot.ni_vp);
1241 NDFREE(&nd, NDF_ONLY_PNBUF);
1245 /* If there was an error, use the original path name. */
1247 bcopy(ptr, buf, len);