2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1982, 1986, 1989, 1993
5 * The Regents of the University of California. All rights reserved.
6 * (c) UNIX System Laboratories, Inc.
7 * All or some portions of this file are derived from material licensed
8 * to the University of California by American Telephone and Telegraph
9 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
10 * the permission of UNIX System Laboratories, Inc.
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13 * modification, are permitted provided that the following conditions
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
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19 * documentation and/or other materials provided with the distribution.
20 * 3. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * @(#)vfs_lookup.c 8.4 (Berkeley) 2/16/94
39 #include <sys/cdefs.h>
40 __FBSDID("$FreeBSD$");
42 #include "opt_capsicum.h"
43 #include "opt_ktrace.h"
45 #include <sys/param.h>
46 #include <sys/systm.h>
47 #include <sys/kernel.h>
48 #include <sys/capsicum.h>
49 #include <sys/fcntl.h>
52 #include <sys/mutex.h>
53 #include <sys/namei.h>
54 #include <sys/vnode.h>
55 #include <sys/mount.h>
56 #include <sys/filedesc.h>
59 #include <sys/syscallsubr.h>
60 #include <sys/sysctl.h>
62 #include <sys/ktrace.h>
65 #include <security/audit/audit.h>
66 #include <security/mac/mac_framework.h>
70 #define NAMEI_DIAGNOSTIC 1
71 #undef NAMEI_DIAGNOSTIC
73 SDT_PROVIDER_DECLARE(vfs);
74 SDT_PROBE_DEFINE3(vfs, namei, lookup, entry, "struct vnode *", "char *",
76 SDT_PROBE_DEFINE2(vfs, namei, lookup, return, "int", "struct vnode *");
78 /* Allocation zone for namei. */
79 uma_zone_t namei_zone;
81 /* Placeholder vnode for mp traversal. */
82 static struct vnode *vp_crossmp;
85 crossmp_vop_islocked(struct vop_islocked_args *ap)
92 crossmp_vop_lock1(struct vop_lock1_args *ap)
95 struct lock *lk __unused;
96 const char *file __unused;
97 int flags, line __unused;
105 if ((flags & LK_SHARED) == 0)
106 panic("invalid lock request for crossmp");
108 WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER, file, line,
109 flags & LK_INTERLOCK ? &VI_MTX(vp)->lock_object : NULL);
110 WITNESS_LOCK(&lk->lock_object, 0, file, line);
111 if ((flags & LK_INTERLOCK) != 0)
113 LOCK_LOG_LOCK("SLOCK", &lk->lock_object, 0, 0, ap->a_file, line);
118 crossmp_vop_unlock(struct vop_unlock_args *ap)
121 struct lock *lk __unused;
126 WITNESS_UNLOCK(&lk->lock_object, 0, LOCK_FILE, LOCK_LINE);
127 LOCK_LOG_LOCK("SUNLOCK", &lk->lock_object, 0, 0, LOCK_FILE,
132 static struct vop_vector crossmp_vnodeops = {
133 .vop_default = &default_vnodeops,
134 .vop_islocked = crossmp_vop_islocked,
135 .vop_lock1 = crossmp_vop_lock1,
136 .vop_unlock = crossmp_vop_unlock,
139 * VFS_VOP_VECTOR_REGISTER(crossmp_vnodeops) is not used here since the vnode
140 * gets allocated early. See nameiinit for the direct call below.
143 struct nameicap_tracker {
145 TAILQ_ENTRY(nameicap_tracker) nm_link;
148 /* Zone for cap mode tracker elements used for dotdot capability checks. */
149 static uma_zone_t nt_zone;
152 nameiinit(void *dummy __unused)
155 namei_zone = uma_zcreate("NAMEI", MAXPATHLEN, NULL, NULL, NULL, NULL,
157 nt_zone = uma_zcreate("rentr", sizeof(struct nameicap_tracker),
158 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
159 vfs_vector_op_register(&crossmp_vnodeops);
160 getnewvnode("crossmp", NULL, &crossmp_vnodeops, &vp_crossmp);
162 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nameiinit, NULL);
164 static int lookup_cap_dotdot = 1;
165 SYSCTL_INT(_vfs, OID_AUTO, lookup_cap_dotdot, CTLFLAG_RWTUN,
166 &lookup_cap_dotdot, 0,
167 "enables \"..\" components in path lookup in capability mode");
168 static int lookup_cap_dotdot_nonlocal = 1;
169 SYSCTL_INT(_vfs, OID_AUTO, lookup_cap_dotdot_nonlocal, CTLFLAG_RWTUN,
170 &lookup_cap_dotdot_nonlocal, 0,
171 "enables \"..\" components in path lookup in capability mode "
172 "on non-local mount");
175 nameicap_tracker_add(struct nameidata *ndp, struct vnode *dp)
177 struct nameicap_tracker *nt;
179 if ((ndp->ni_lcf & NI_LCF_CAP_DOTDOT) == 0 || dp->v_type != VDIR)
181 if ((ndp->ni_lcf & (NI_LCF_BENEATH_ABS | NI_LCF_BENEATH_LATCHED)) ==
182 NI_LCF_BENEATH_ABS) {
183 MPASS((ndp->ni_lcf & NI_LCF_LATCH) != 0);
184 if (dp != ndp->ni_beneath_latch)
186 ndp->ni_lcf |= NI_LCF_BENEATH_LATCHED;
188 nt = uma_zalloc(nt_zone, M_WAITOK);
191 TAILQ_INSERT_TAIL(&ndp->ni_cap_tracker, nt, nm_link);
195 nameicap_cleanup(struct nameidata *ndp, bool clean_latch)
197 struct nameicap_tracker *nt, *nt1;
199 KASSERT(TAILQ_EMPTY(&ndp->ni_cap_tracker) ||
200 (ndp->ni_lcf & NI_LCF_CAP_DOTDOT) != 0, ("not strictrelative"));
201 TAILQ_FOREACH_SAFE(nt, &ndp->ni_cap_tracker, nm_link, nt1) {
202 TAILQ_REMOVE(&ndp->ni_cap_tracker, nt, nm_link);
204 uma_zfree(nt_zone, nt);
206 if (clean_latch && (ndp->ni_lcf & NI_LCF_LATCH) != 0) {
207 ndp->ni_lcf &= ~NI_LCF_LATCH;
208 vrele(ndp->ni_beneath_latch);
213 * For dotdot lookups in capability mode, only allow the component
214 * lookup to succeed if the resulting directory was already traversed
215 * during the operation. Also fail dotdot lookups for non-local
216 * filesystems, where external agents might assist local lookups to
217 * escape the compartment.
220 nameicap_check_dotdot(struct nameidata *ndp, struct vnode *dp)
222 struct nameicap_tracker *nt;
225 if ((ndp->ni_lcf & NI_LCF_CAP_DOTDOT) == 0 || dp == NULL ||
229 if (lookup_cap_dotdot_nonlocal == 0 && mp != NULL &&
230 (mp->mnt_flag & MNT_LOCAL) == 0)
231 return (ENOTCAPABLE);
232 TAILQ_FOREACH_REVERSE(nt, &ndp->ni_cap_tracker, nameicap_tracker_head,
237 if ((ndp->ni_lcf & NI_LCF_BENEATH_ABS) != 0) {
238 ndp->ni_lcf &= ~NI_LCF_BENEATH_LATCHED;
239 nameicap_cleanup(ndp, false);
242 return (ENOTCAPABLE);
246 namei_cleanup_cnp(struct componentname *cnp)
249 uma_zfree(namei_zone, cnp->cn_pnbuf);
251 cnp->cn_pnbuf = NULL;
252 cnp->cn_nameptr = NULL;
257 namei_handle_root(struct nameidata *ndp, struct vnode **dpp)
259 struct componentname *cnp;
262 if ((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) != 0) {
264 if (KTRPOINT(curthread, KTR_CAPFAIL))
265 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
267 return (ENOTCAPABLE);
269 if ((cnp->cn_flags & BENEATH) != 0) {
270 ndp->ni_lcf |= NI_LCF_BENEATH_ABS;
271 ndp->ni_lcf &= ~NI_LCF_BENEATH_LATCHED;
272 nameicap_cleanup(ndp, false);
274 while (*(cnp->cn_nameptr) == '/') {
278 *dpp = ndp->ni_rootdir;
284 * Convert a pathname into a pointer to a locked vnode.
286 * The FOLLOW flag is set when symbolic links are to be followed
287 * when they occur at the end of the name translation process.
288 * Symbolic links are always followed for all other pathname
289 * components other than the last.
291 * The segflg defines whether the name is to be copied from user
292 * space or kernel space.
294 * Overall outline of namei:
297 * get starting directory
298 * while (!done && !error) {
299 * call lookup to search path.
300 * if symbolic link, massage name in buffer and continue
304 namei(struct nameidata *ndp)
306 struct filedesc *fdp; /* pointer to file descriptor state */
307 char *cp; /* pointer into pathname argument */
308 struct vnode *dp; /* the directory we are searching */
309 struct iovec aiov; /* uio for reading symbolic links */
310 struct componentname *cnp;
314 struct filecaps dirfd_caps;
316 int error, linklen, startdir_used;
321 ndp->ni_cnd.cn_cred = ndp->ni_cnd.cn_thread->td_ucred;
322 KASSERT(cnp->cn_cred && p, ("namei: bad cred/proc"));
323 KASSERT((cnp->cn_nameiop & (~OPMASK)) == 0,
324 ("namei: nameiop contaminated with flags"));
325 KASSERT((cnp->cn_flags & OPMASK) == 0,
326 ("namei: flags contaminated with nameiops"));
327 MPASS(ndp->ni_startdir == NULL || ndp->ni_startdir->v_type == VDIR ||
328 ndp->ni_startdir->v_type == VBAD);
330 TAILQ_INIT(&ndp->ni_cap_tracker);
333 /* We will set this ourselves if we need it. */
334 cnp->cn_flags &= ~TRAILINGSLASH;
337 * Get a buffer for the name to be translated, and copy the
338 * name into the buffer.
340 if ((cnp->cn_flags & HASBUF) == 0)
341 cnp->cn_pnbuf = uma_zalloc(namei_zone, M_WAITOK);
342 if (ndp->ni_segflg == UIO_SYSSPACE)
343 error = copystr(ndp->ni_dirp, cnp->cn_pnbuf, MAXPATHLEN,
346 error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf, MAXPATHLEN,
350 * Don't allow empty pathnames.
352 if (error == 0 && *cnp->cn_pnbuf == '\0')
355 #ifdef CAPABILITY_MODE
357 * In capability mode, lookups must be restricted to happen in
358 * the subtree with the root specified by the file descriptor:
359 * - The root must be real file descriptor, not the pseudo-descriptor
361 * - The passed path must be relative and not absolute.
362 * - If lookup_cap_dotdot is disabled, path must not contain the
364 * - If lookup_cap_dotdot is enabled, we verify that all '..'
365 * components lookups result in the directories which were
366 * previously walked by us, which prevents an escape from
369 if (error == 0 && IN_CAPABILITY_MODE(td) &&
370 (cnp->cn_flags & NOCAPCHECK) == 0) {
371 ndp->ni_lcf |= NI_LCF_STRICTRELATIVE;
372 if (ndp->ni_dirfd == AT_FDCWD) {
374 if (KTRPOINT(td, KTR_CAPFAIL))
375 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
382 namei_cleanup_cnp(cnp);
388 if (KTRPOINT(td, KTR_NAMEI)) {
389 KASSERT(cnp->cn_thread == curthread,
390 ("namei not using curthread"));
391 ktrnamei(cnp->cn_pnbuf);
395 * Get starting point for the translation.
398 ndp->ni_rootdir = fdp->fd_rdir;
399 vrefact(ndp->ni_rootdir);
400 ndp->ni_topdir = fdp->fd_jdir;
403 * If we are auditing the kernel pathname, save the user pathname.
405 if (cnp->cn_flags & AUDITVNODE1)
406 AUDIT_ARG_UPATH1(td, ndp->ni_dirfd, cnp->cn_pnbuf);
407 if (cnp->cn_flags & AUDITVNODE2)
408 AUDIT_ARG_UPATH2(td, ndp->ni_dirfd, cnp->cn_pnbuf);
412 cnp->cn_nameptr = cnp->cn_pnbuf;
413 if (cnp->cn_pnbuf[0] == '/') {
414 ndp->ni_resflags |= NIRES_ABS;
415 error = namei_handle_root(ndp, &dp);
417 if (ndp->ni_startdir != NULL) {
418 dp = ndp->ni_startdir;
420 } else if (ndp->ni_dirfd == AT_FDCWD) {
424 rights = ndp->ni_rightsneeded;
425 cap_rights_set(&rights, CAP_LOOKUP);
427 if (cnp->cn_flags & AUDITVNODE1)
428 AUDIT_ARG_ATFD1(ndp->ni_dirfd);
429 if (cnp->cn_flags & AUDITVNODE2)
430 AUDIT_ARG_ATFD2(ndp->ni_dirfd);
431 error = fgetvp_rights(td, ndp->ni_dirfd,
432 &rights, &ndp->ni_filecaps, &dp);
437 * If file descriptor doesn't have all rights,
438 * all lookups relative to it must also be
442 if (!cap_rights_contains(&ndp->ni_filecaps.fc_rights,
444 ndp->ni_filecaps.fc_fcntls != CAP_FCNTL_ALL ||
445 ndp->ni_filecaps.fc_nioctls != -1) {
446 ndp->ni_lcf |= NI_LCF_STRICTRELATIVE;
450 if (error == 0 && dp->v_type != VDIR)
453 if (error == 0 && (cnp->cn_flags & BENEATH) != 0) {
454 if (ndp->ni_dirfd == AT_FDCWD) {
455 ndp->ni_beneath_latch = fdp->fd_cdir;
456 vrefact(ndp->ni_beneath_latch);
458 rights = ndp->ni_rightsneeded;
459 cap_rights_set(&rights, CAP_LOOKUP);
460 error = fgetvp_rights(td, ndp->ni_dirfd, &rights,
461 &dirfd_caps, &ndp->ni_beneath_latch);
462 if (error == 0 && dp->v_type != VDIR) {
463 vrele(ndp->ni_beneath_latch);
468 ndp->ni_lcf |= NI_LCF_LATCH;
470 FILEDESC_SUNLOCK(fdp);
471 if (ndp->ni_startdir != NULL && !startdir_used)
472 vrele(ndp->ni_startdir);
478 MPASS((ndp->ni_lcf & (NI_LCF_BENEATH_ABS | NI_LCF_LATCH)) !=
480 if (((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) != 0 &&
481 lookup_cap_dotdot != 0) ||
482 ((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) == 0 &&
483 (cnp->cn_flags & BENEATH) != 0))
484 ndp->ni_lcf |= NI_LCF_CAP_DOTDOT;
485 SDT_PROBE3(vfs, namei, lookup, entry, dp, cnp->cn_pnbuf,
488 ndp->ni_startdir = dp;
493 * If not a symbolic link, we're done.
495 if ((cnp->cn_flags & ISSYMLINK) == 0) {
496 vrele(ndp->ni_rootdir);
497 if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) {
498 namei_cleanup_cnp(cnp);
500 cnp->cn_flags |= HASBUF;
501 if ((ndp->ni_lcf & (NI_LCF_BENEATH_ABS |
502 NI_LCF_BENEATH_LATCHED)) == NI_LCF_BENEATH_ABS) {
506 nameicap_cleanup(ndp, true);
507 SDT_PROBE2(vfs, namei, lookup, return, error,
508 (error == 0 ? ndp->ni_vp : NULL));
511 if (ndp->ni_loopcnt++ >= MAXSYMLINKS) {
516 if ((cnp->cn_flags & NOMACCHECK) == 0) {
517 error = mac_vnode_check_readlink(td->td_ucred,
523 if (ndp->ni_pathlen > 1)
524 cp = uma_zalloc(namei_zone, M_WAITOK);
528 aiov.iov_len = MAXPATHLEN;
529 auio.uio_iov = &aiov;
532 auio.uio_rw = UIO_READ;
533 auio.uio_segflg = UIO_SYSSPACE;
535 auio.uio_resid = MAXPATHLEN;
536 error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred);
538 if (ndp->ni_pathlen > 1)
539 uma_zfree(namei_zone, cp);
542 linklen = MAXPATHLEN - auio.uio_resid;
544 if (ndp->ni_pathlen > 1)
545 uma_zfree(namei_zone, cp);
549 if (linklen + ndp->ni_pathlen > MAXPATHLEN) {
550 if (ndp->ni_pathlen > 1)
551 uma_zfree(namei_zone, cp);
552 error = ENAMETOOLONG;
555 if (ndp->ni_pathlen > 1) {
556 bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen);
557 uma_zfree(namei_zone, cnp->cn_pnbuf);
560 cnp->cn_pnbuf[linklen] = '\0';
561 ndp->ni_pathlen += linklen;
565 * Check if root directory should replace current directory.
567 cnp->cn_nameptr = cnp->cn_pnbuf;
568 if (*(cnp->cn_nameptr) == '/') {
570 error = namei_handle_root(ndp, &dp);
579 vrele(ndp->ni_rootdir);
581 namei_cleanup_cnp(cnp);
582 nameicap_cleanup(ndp, true);
583 SDT_PROBE2(vfs, namei, lookup, return, error, NULL);
588 compute_cn_lkflags(struct mount *mp, int lkflags, int cnflags)
591 if (mp == NULL || ((lkflags & LK_SHARED) &&
592 (!(mp->mnt_kern_flag & MNTK_LOOKUP_SHARED) ||
593 ((cnflags & ISDOTDOT) &&
594 (mp->mnt_kern_flag & MNTK_LOOKUP_EXCL_DOTDOT))))) {
595 lkflags &= ~LK_SHARED;
596 lkflags |= LK_EXCLUSIVE;
598 lkflags |= LK_NODDLKTREAT;
603 needs_exclusive_leaf(struct mount *mp, int flags)
607 * Intermediate nodes can use shared locks, we only need to
608 * force an exclusive lock for leaf nodes.
610 if ((flags & (ISLASTCN | LOCKLEAF)) != (ISLASTCN | LOCKLEAF))
613 /* Always use exclusive locks if LOCKSHARED isn't set. */
614 if (!(flags & LOCKSHARED))
618 * For lookups during open(), if the mount point supports
619 * extended shared operations, then use a shared lock for the
620 * leaf node, otherwise use an exclusive lock.
622 if ((flags & ISOPEN) != 0)
623 return (!MNT_EXTENDED_SHARED(mp));
626 * Lookup requests outside of open() that specify LOCKSHARED
627 * only need a shared lock on the leaf vnode.
634 * This is a very central and rather complicated routine.
636 * The pathname is pointed to by ni_ptr and is of length ni_pathlen.
637 * The starting directory is taken from ni_startdir. The pathname is
638 * descended until done, or a symbolic link is encountered. The variable
639 * ni_more is clear if the path is completed; it is set to one if a
640 * symbolic link needing interpretation is encountered.
642 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on
643 * whether the name is to be looked up, created, renamed, or deleted.
644 * When CREATE, RENAME, or DELETE is specified, information usable in
645 * creating, renaming, or deleting a directory entry may be calculated.
646 * If flag has LOCKPARENT or'ed into it, the parent directory is returned
647 * locked. If flag has WANTPARENT or'ed into it, the parent directory is
648 * returned unlocked. Otherwise the parent directory is not returned. If
649 * the target of the pathname exists and LOCKLEAF is or'ed into the flag
650 * the target is returned locked, otherwise it is returned unlocked.
651 * When creating or renaming and LOCKPARENT is specified, the target may not
652 * be ".". When deleting and LOCKPARENT is specified, the target may be ".".
654 * Overall outline of lookup:
657 * identify next component of name at ndp->ni_ptr
658 * handle degenerate case where name is null string
659 * if .. and crossing mount points and on mounted filesys, find parent
660 * call VOP_LOOKUP routine for next component name
661 * directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set
662 * component vnode returned in ni_vp (if it exists), locked.
663 * if result vnode is mounted on and crossing mount points,
664 * find mounted on vnode
665 * if more components of name, do next level at dirloop
666 * return the answer in ni_vp, locked if LOCKLEAF set
667 * if LOCKPARENT set, return locked parent in ni_dvp
668 * if WANTPARENT set, return unlocked parent in ni_dvp
671 lookup(struct nameidata *ndp)
673 char *cp; /* pointer into pathname argument */
674 char *prev_ni_next; /* saved ndp->ni_next */
675 struct vnode *dp = NULL; /* the directory we are searching */
676 struct vnode *tdp; /* saved dp */
677 struct mount *mp; /* mount table entry */
679 size_t prev_ni_pathlen; /* saved ndp->ni_pathlen */
680 int docache; /* == 0 do not cache last component */
681 int wantparent; /* 1 => wantparent or lockparent flag */
682 int rdonly; /* lookup read-only flag bit */
684 int dpunlocked = 0; /* dp has already been unlocked */
685 int relookup = 0; /* do not consume the path component */
686 struct componentname *cnp = &ndp->ni_cnd;
691 * Setup: break out flag bits into variables.
694 wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT);
695 KASSERT(cnp->cn_nameiop == LOOKUP || wantparent,
696 ("CREATE, DELETE, RENAME require LOCKPARENT or WANTPARENT."));
697 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE;
698 if (cnp->cn_nameiop == DELETE ||
699 (wantparent && cnp->cn_nameiop != CREATE &&
700 cnp->cn_nameiop != LOOKUP))
702 rdonly = cnp->cn_flags & RDONLY;
703 cnp->cn_flags &= ~ISSYMLINK;
706 * We use shared locks until we hit the parent of the last cn then
707 * we adjust based on the requesting flags.
709 cnp->cn_lkflags = LK_SHARED;
710 dp = ndp->ni_startdir;
711 ndp->ni_startdir = NULLVP;
713 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | LK_RETRY,
718 * Search a new directory.
720 * The last component of the filename is left accessible via
721 * cnp->cn_nameptr for callers that need the name. Callers needing
722 * the name set the SAVENAME flag. When done, they assume
723 * responsibility for freeing the pathname buffer.
725 for (cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++)
727 cnp->cn_namelen = cp - cnp->cn_nameptr;
728 if (cnp->cn_namelen > NAME_MAX) {
729 error = ENAMETOOLONG;
732 #ifdef NAMEI_DIAGNOSTIC
735 printf("{%s}: ", cnp->cn_nameptr);
738 prev_ni_pathlen = ndp->ni_pathlen;
739 ndp->ni_pathlen -= cnp->cn_namelen;
740 KASSERT(ndp->ni_pathlen <= PATH_MAX,
741 ("%s: ni_pathlen underflow to %zd\n", __func__, ndp->ni_pathlen));
742 prev_ni_next = ndp->ni_next;
746 * Replace multiple slashes by a single slash and trailing slashes
747 * by a null. This must be done before VOP_LOOKUP() because some
748 * fs's don't know about trailing slashes. Remember if there were
749 * trailing slashes to handle symlinks, existing non-directories
750 * and non-existing files that won't be directories specially later.
752 while (*cp == '/' && (cp[1] == '/' || cp[1] == '\0')) {
756 *ndp->ni_next = '\0';
757 cnp->cn_flags |= TRAILINGSLASH;
762 cnp->cn_flags |= MAKEENTRY;
763 if (*cp == '\0' && docache == 0)
764 cnp->cn_flags &= ~MAKEENTRY;
765 if (cnp->cn_namelen == 2 &&
766 cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.')
767 cnp->cn_flags |= ISDOTDOT;
769 cnp->cn_flags &= ~ISDOTDOT;
770 if (*ndp->ni_next == 0)
771 cnp->cn_flags |= ISLASTCN;
773 cnp->cn_flags &= ~ISLASTCN;
775 if ((cnp->cn_flags & ISLASTCN) != 0 &&
776 cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.' &&
777 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
782 nameicap_tracker_add(ndp, dp);
785 * Check for degenerate name (e.g. / or "")
786 * which is a way of talking about a directory,
787 * e.g. like "/." or ".".
789 if (cnp->cn_nameptr[0] == '\0') {
790 if (dp->v_type != VDIR) {
794 if (cnp->cn_nameiop != LOOKUP) {
804 if (cnp->cn_flags & AUDITVNODE1)
805 AUDIT_ARG_VNODE1(dp);
806 else if (cnp->cn_flags & AUDITVNODE2)
807 AUDIT_ARG_VNODE2(dp);
809 if (!(cnp->cn_flags & (LOCKPARENT | LOCKLEAF)))
811 /* XXX This should probably move to the top of function. */
812 if (cnp->cn_flags & SAVESTART)
813 panic("lookup: SAVESTART");
818 * Handle "..": five special cases.
819 * 0. If doing a capability lookup and lookup_cap_dotdot is
820 * disabled, return ENOTCAPABLE.
821 * 1. Return an error if this is the last component of
822 * the name and the operation is DELETE or RENAME.
823 * 2. If at root directory (e.g. after chroot)
824 * or at absolute root directory
825 * then ignore it so can't get out.
826 * 3. If this vnode is the root of a mounted
827 * filesystem, then replace it with the
828 * vnode which was mounted on so we take the
829 * .. in the other filesystem.
830 * 4. If the vnode is the top directory of
831 * the jail or chroot, don't let them out.
832 * 5. If doing a capability lookup and lookup_cap_dotdot is
833 * enabled, return ENOTCAPABLE if the lookup would escape
834 * from the initial file descriptor directory. Checks are
835 * done by ensuring that namei() already traversed the
836 * result of dotdot lookup.
838 if (cnp->cn_flags & ISDOTDOT) {
839 if ((ndp->ni_lcf & (NI_LCF_STRICTRELATIVE | NI_LCF_CAP_DOTDOT))
840 == NI_LCF_STRICTRELATIVE) {
842 if (KTRPOINT(curthread, KTR_CAPFAIL))
843 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
848 if ((cnp->cn_flags & ISLASTCN) != 0 &&
849 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
854 for (pr = cnp->cn_cred->cr_prison; pr != NULL;
856 if (dp == pr->pr_root)
858 if (dp == ndp->ni_rootdir ||
859 dp == ndp->ni_topdir ||
862 ((dp->v_vflag & VV_ROOT) != 0 &&
863 (cnp->cn_flags & NOCROSSMOUNT) != 0)) {
869 if ((dp->v_vflag & VV_ROOT) == 0)
871 if (VN_IS_DOOMED(dp)) { /* forced unmount */
876 dp = dp->v_mount->mnt_vnodecovered;
880 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags |
881 LK_RETRY, ISDOTDOT));
882 error = nameicap_check_dotdot(ndp, dp);
885 if (KTRPOINT(curthread, KTR_CAPFAIL))
886 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
894 * We now have a segment name to search for, and a directory to search.
898 if ((cnp->cn_flags & NOMACCHECK) == 0) {
899 error = mac_vnode_check_lookup(cnp->cn_thread->td_ucred, dp,
907 ASSERT_VOP_LOCKED(dp, "lookup");
909 * If we have a shared lock we may need to upgrade the lock for the
912 if ((cnp->cn_flags & LOCKPARENT) && (cnp->cn_flags & ISLASTCN) &&
913 dp != vp_crossmp && VOP_ISLOCKED(dp) == LK_SHARED)
914 vn_lock(dp, LK_UPGRADE|LK_RETRY);
915 if (VN_IS_DOOMED(dp)) {
920 * If we're looking up the last component and we need an exclusive
921 * lock, adjust our lkflags.
923 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags))
924 cnp->cn_lkflags = LK_EXCLUSIVE;
925 #ifdef NAMEI_DIAGNOSTIC
926 vn_printf(dp, "lookup in ");
928 lkflags_save = cnp->cn_lkflags;
929 cnp->cn_lkflags = compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags,
931 error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp);
932 cnp->cn_lkflags = lkflags_save;
934 KASSERT(ndp->ni_vp == NULL, ("leaf should be empty"));
935 #ifdef NAMEI_DIAGNOSTIC
936 printf("not found\n");
938 if ((error == ENOENT) &&
939 (dp->v_vflag & VV_ROOT) && (dp->v_mount != NULL) &&
940 (dp->v_mount->mnt_flag & MNT_UNION)) {
942 dp = dp->v_mount->mnt_vnodecovered;
946 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags |
947 LK_RETRY, cnp->cn_flags));
948 nameicap_tracker_add(ndp, dp);
952 if (error == ERELOOKUP) {
960 if (error != EJUSTRETURN)
963 * At this point, we know we're at the end of the
964 * pathname. If creating / renaming, we can consider
965 * allowing the file or directory to be created / renamed,
966 * provided we're not on a read-only filesystem.
972 /* trailing slash only allowed for directories */
973 if ((cnp->cn_flags & TRAILINGSLASH) &&
974 !(cnp->cn_flags & WILLBEDIR)) {
978 if ((cnp->cn_flags & LOCKPARENT) == 0)
981 * We return with ni_vp NULL to indicate that the entry
982 * doesn't currently exist, leaving a pointer to the
983 * (possibly locked) directory vnode in ndp->ni_dvp.
985 if (cnp->cn_flags & SAVESTART) {
986 ndp->ni_startdir = ndp->ni_dvp;
987 VREF(ndp->ni_startdir);
993 #ifdef NAMEI_DIAGNOSTIC
999 * Check to see if the vnode has been mounted on;
1000 * if so find the root of the mounted filesystem.
1002 while (dp->v_type == VDIR && (mp = dp->v_mountedhere) &&
1003 (cnp->cn_flags & NOCROSSMOUNT) == 0) {
1004 if (vfs_busy(mp, 0))
1007 if (dp != ndp->ni_dvp)
1011 vrefact(vp_crossmp);
1012 ndp->ni_dvp = vp_crossmp;
1013 error = VFS_ROOT(mp, compute_cn_lkflags(mp, cnp->cn_lkflags,
1014 cnp->cn_flags), &tdp);
1016 if (vn_lock(vp_crossmp, LK_SHARED | LK_NOWAIT))
1017 panic("vp_crossmp exclusively locked or reclaimed");
1022 ndp->ni_vp = dp = tdp;
1026 * Check for symbolic link
1028 if ((dp->v_type == VLNK) &&
1029 ((cnp->cn_flags & FOLLOW) || (cnp->cn_flags & TRAILINGSLASH) ||
1030 *ndp->ni_next == '/')) {
1031 cnp->cn_flags |= ISSYMLINK;
1032 if (VN_IS_DOOMED(dp)) {
1034 * We can't know whether the directory was mounted with
1035 * NOSYMFOLLOW, so we can't follow safely.
1040 if (dp->v_mount->mnt_flag & MNT_NOSYMFOLLOW) {
1045 * Symlink code always expects an unlocked dvp.
1047 if (ndp->ni_dvp != ndp->ni_vp) {
1048 VOP_UNLOCK(ndp->ni_dvp);
1049 ni_dvp_unlocked = 1;
1056 * Not a symbolic link that we will follow. Continue with the
1057 * next component if there is any; otherwise, we're done.
1059 KASSERT((cnp->cn_flags & ISLASTCN) || *ndp->ni_next == '/',
1060 ("lookup: invalid path state."));
1063 ndp->ni_pathlen = prev_ni_pathlen;
1064 ndp->ni_next = prev_ni_next;
1065 if (ndp->ni_dvp != dp)
1071 if (cnp->cn_flags & ISDOTDOT) {
1072 error = nameicap_check_dotdot(ndp, ndp->ni_vp);
1075 if (KTRPOINT(curthread, KTR_CAPFAIL))
1076 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
1081 if (*ndp->ni_next == '/') {
1082 cnp->cn_nameptr = ndp->ni_next;
1083 while (*cnp->cn_nameptr == '/') {
1087 if (ndp->ni_dvp != dp)
1094 * If we're processing a path with a trailing slash,
1095 * check that the end result is a directory.
1097 if ((cnp->cn_flags & TRAILINGSLASH) && dp->v_type != VDIR) {
1102 * Disallow directory write attempts on read-only filesystems.
1105 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
1109 if (cnp->cn_flags & SAVESTART) {
1110 ndp->ni_startdir = ndp->ni_dvp;
1111 VREF(ndp->ni_startdir);
1114 ni_dvp_unlocked = 2;
1115 if (ndp->ni_dvp != dp)
1119 } else if ((cnp->cn_flags & LOCKPARENT) == 0 && ndp->ni_dvp != dp) {
1120 VOP_UNLOCK(ndp->ni_dvp);
1121 ni_dvp_unlocked = 1;
1124 if (cnp->cn_flags & AUDITVNODE1)
1125 AUDIT_ARG_VNODE1(dp);
1126 else if (cnp->cn_flags & AUDITVNODE2)
1127 AUDIT_ARG_VNODE2(dp);
1129 if ((cnp->cn_flags & LOCKLEAF) == 0)
1133 * Because of shared lookup we may have the vnode shared locked, but
1134 * the caller may want it to be exclusively locked.
1136 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags) &&
1137 VOP_ISLOCKED(dp) != LK_EXCLUSIVE) {
1138 vn_lock(dp, LK_UPGRADE | LK_RETRY);
1139 if (VN_IS_DOOMED(dp)) {
1147 if (ni_dvp_unlocked != 2) {
1148 if (dp != ndp->ni_dvp && !ni_dvp_unlocked)
1161 * relookup - lookup a path name component
1162 * Used by lookup to re-acquire things.
1165 relookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp)
1167 struct vnode *dp = NULL; /* the directory we are searching */
1168 int wantparent; /* 1 => wantparent or lockparent flag */
1169 int rdonly; /* lookup read-only flag bit */
1172 KASSERT(cnp->cn_flags & ISLASTCN,
1173 ("relookup: Not given last component."));
1175 * Setup: break out flag bits into variables.
1177 wantparent = cnp->cn_flags & (LOCKPARENT|WANTPARENT);
1178 KASSERT(wantparent, ("relookup: parent not wanted."));
1179 rdonly = cnp->cn_flags & RDONLY;
1180 cnp->cn_flags &= ~ISSYMLINK;
1182 cnp->cn_lkflags = LK_EXCLUSIVE;
1183 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY);
1186 * Search a new directory.
1188 * The last component of the filename is left accessible via
1189 * cnp->cn_nameptr for callers that need the name. Callers needing
1190 * the name set the SAVENAME flag. When done, they assume
1191 * responsibility for freeing the pathname buffer.
1193 #ifdef NAMEI_DIAGNOSTIC
1194 printf("{%s}: ", cnp->cn_nameptr);
1198 * Check for "" which represents the root directory after slash
1201 if (cnp->cn_nameptr[0] == '\0') {
1203 * Support only LOOKUP for "/" because lookup()
1204 * can't succeed for CREATE, DELETE and RENAME.
1206 KASSERT(cnp->cn_nameiop == LOOKUP, ("nameiop must be LOOKUP"));
1207 KASSERT(dp->v_type == VDIR, ("dp is not a directory"));
1209 if (!(cnp->cn_flags & LOCKLEAF))
1212 /* XXX This should probably move to the top of function. */
1213 if (cnp->cn_flags & SAVESTART)
1214 panic("lookup: SAVESTART");
1218 if (cnp->cn_flags & ISDOTDOT)
1219 panic ("relookup: lookup on dot-dot");
1222 * We now have a segment name to search for, and a directory to search.
1224 #ifdef NAMEI_DIAGNOSTIC
1225 vn_printf(dp, "search in ");
1227 if ((error = VOP_LOOKUP(dp, vpp, cnp)) != 0) {
1228 KASSERT(*vpp == NULL, ("leaf should be empty"));
1229 if (error != EJUSTRETURN)
1232 * If creating and at end of pathname, then can consider
1233 * allowing file to be created.
1239 /* ASSERT(dvp == ndp->ni_startdir) */
1240 if (cnp->cn_flags & SAVESTART)
1242 if ((cnp->cn_flags & LOCKPARENT) == 0)
1245 * We return with ni_vp NULL to indicate that the entry
1246 * doesn't currently exist, leaving a pointer to the
1247 * (possibly locked) directory vnode in ndp->ni_dvp.
1255 * Disallow directory write attempts on read-only filesystems.
1258 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
1267 * Set the parent lock/ref state to the requested state.
1269 if ((cnp->cn_flags & LOCKPARENT) == 0 && dvp != dp) {
1274 } else if (!wantparent)
1277 * Check for symbolic link
1279 KASSERT(dp->v_type != VLNK || !(cnp->cn_flags & FOLLOW),
1280 ("relookup: symlink found.\n"));
1282 /* ASSERT(dvp == ndp->ni_startdir) */
1283 if (cnp->cn_flags & SAVESTART)
1286 if ((cnp->cn_flags & LOCKLEAF) == 0)
1296 NDINIT_ALL(struct nameidata *ndp, u_long op, u_long flags, enum uio_seg segflg,
1297 const char *namep, int dirfd, struct vnode *startdir, cap_rights_t *rightsp,
1301 ndp->ni_cnd.cn_nameiop = op;
1302 ndp->ni_cnd.cn_flags = flags;
1303 ndp->ni_segflg = segflg;
1304 ndp->ni_dirp = namep;
1305 ndp->ni_dirfd = dirfd;
1306 ndp->ni_startdir = startdir;
1307 ndp->ni_resflags = 0;
1308 filecaps_init(&ndp->ni_filecaps);
1309 ndp->ni_cnd.cn_thread = td;
1310 if (rightsp != NULL)
1311 ndp->ni_rightsneeded = *rightsp;
1313 cap_rights_init(&ndp->ni_rightsneeded);
1317 * Free data allocated by namei(); see namei(9) for details.
1320 NDFREE(struct nameidata *ndp, const u_int flags)
1328 if (!(flags & NDF_NO_FREE_PNBUF) &&
1329 (ndp->ni_cnd.cn_flags & HASBUF)) {
1330 uma_zfree(namei_zone, ndp->ni_cnd.cn_pnbuf);
1331 ndp->ni_cnd.cn_flags &= ~HASBUF;
1333 if (!(flags & NDF_NO_VP_UNLOCK) &&
1334 (ndp->ni_cnd.cn_flags & LOCKLEAF) && ndp->ni_vp)
1336 if (!(flags & NDF_NO_DVP_UNLOCK) &&
1337 (ndp->ni_cnd.cn_flags & LOCKPARENT) &&
1338 ndp->ni_dvp != ndp->ni_vp)
1340 if (!(flags & NDF_NO_VP_RELE) && ndp->ni_vp) {
1349 VOP_UNLOCK(ndp->ni_vp);
1350 if (!(flags & NDF_NO_DVP_RELE) &&
1351 (ndp->ni_cnd.cn_flags & (LOCKPARENT|WANTPARENT))) {
1360 VOP_UNLOCK(ndp->ni_dvp);
1361 if (!(flags & NDF_NO_STARTDIR_RELE) &&
1362 (ndp->ni_cnd.cn_flags & SAVESTART)) {
1363 vrele(ndp->ni_startdir);
1364 ndp->ni_startdir = NULL;
1369 * Determine if there is a suitable alternate filename under the specified
1370 * prefix for the specified path. If the create flag is set, then the
1371 * alternate prefix will be used so long as the parent directory exists.
1372 * This is used by the various compatibility ABIs so that Linux binaries prefer
1373 * files under /compat/linux for example. The chosen path (whether under
1374 * the prefix or under /) is returned in a kernel malloc'd buffer pointed
1375 * to by pathbuf. The caller is responsible for free'ing the buffer from
1376 * the M_TEMP bucket if one is returned.
1379 kern_alternate_path(struct thread *td, const char *prefix, const char *path,
1380 enum uio_seg pathseg, char **pathbuf, int create, int dirfd)
1382 struct nameidata nd, ndroot;
1383 char *ptr, *buf, *cp;
1387 buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
1390 /* Copy the prefix into the new pathname as a starting point. */
1391 len = strlcpy(buf, prefix, MAXPATHLEN);
1392 if (len >= MAXPATHLEN) {
1397 sz = MAXPATHLEN - len;
1400 /* Append the filename to the prefix. */
1401 if (pathseg == UIO_SYSSPACE)
1402 error = copystr(path, ptr, sz, &len);
1404 error = copyinstr(path, ptr, sz, &len);
1412 /* Only use a prefix with absolute pathnames. */
1418 if (dirfd != AT_FDCWD) {
1420 * We want the original because the "prefix" is
1421 * included in the already opened dirfd.
1423 bcopy(ptr, buf, len);
1428 * We know that there is a / somewhere in this pathname.
1429 * Search backwards for it, to find the file's parent dir
1430 * to see if it exists in the alternate tree. If it does,
1431 * and we want to create a file (cflag is set). We don't
1432 * need to worry about the root comparison in this case.
1436 for (cp = &ptr[len] - 1; *cp != '/'; cp--);
1439 NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_SYSSPACE, buf, td);
1445 NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_SYSSPACE, buf, td);
1452 * We now compare the vnode of the prefix to the one
1453 * vnode asked. If they resolve to be the same, then we
1454 * ignore the match so that the real root gets used.
1455 * This avoids the problem of traversing "../.." to find the
1456 * root directory and never finding it, because "/" resolves
1457 * to the emulation root directory. This is expensive :-(
1459 NDINIT(&ndroot, LOOKUP, FOLLOW, UIO_SYSSPACE, prefix,
1462 /* We shouldn't ever get an error from this namei(). */
1463 error = namei(&ndroot);
1465 if (nd.ni_vp == ndroot.ni_vp)
1468 NDFREE(&ndroot, NDF_ONLY_PNBUF);
1469 vrele(ndroot.ni_vp);
1473 NDFREE(&nd, NDF_ONLY_PNBUF);
1477 /* If there was an error, use the original path name. */
1479 bcopy(ptr, buf, len);