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
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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 <machine/_inttypes.h>
68 #include <security/audit/audit.h>
69 #include <security/mac/mac_framework.h>
73 #define NAMEI_DIAGNOSTIC 1
74 #undef NAMEI_DIAGNOSTIC
76 SDT_PROVIDER_DEFINE(vfs);
77 SDT_PROBE_DEFINE4(vfs, namei, lookup, entry, "struct vnode *", "char *",
78 "unsigned long", "bool");
79 SDT_PROBE_DEFINE3(vfs, namei, lookup, return, "int", "struct vnode *", "bool");
81 /* Allocation zone for namei. */
82 uma_zone_t namei_zone;
84 /* Placeholder vnode for mp traversal. */
85 static struct vnode *vp_crossmp;
88 crossmp_vop_islocked(struct vop_islocked_args *ap)
95 crossmp_vop_lock1(struct vop_lock1_args *ap)
98 struct lock *lk __unused;
99 const char *file __unused;
100 int flags, line __unused;
108 if ((flags & LK_SHARED) == 0)
109 panic("invalid lock request for crossmp");
111 WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER, file, line,
112 flags & LK_INTERLOCK ? &VI_MTX(vp)->lock_object : NULL);
113 WITNESS_LOCK(&lk->lock_object, 0, file, line);
114 if ((flags & LK_INTERLOCK) != 0)
116 LOCK_LOG_LOCK("SLOCK", &lk->lock_object, 0, 0, ap->a_file, line);
121 crossmp_vop_unlock(struct vop_unlock_args *ap)
124 struct lock *lk __unused;
129 WITNESS_UNLOCK(&lk->lock_object, 0, LOCK_FILE, LOCK_LINE);
130 LOCK_LOG_LOCK("SUNLOCK", &lk->lock_object, 0, 0, LOCK_FILE,
135 static struct vop_vector crossmp_vnodeops = {
136 .vop_default = &default_vnodeops,
137 .vop_islocked = crossmp_vop_islocked,
138 .vop_lock1 = crossmp_vop_lock1,
139 .vop_unlock = crossmp_vop_unlock,
142 * VFS_VOP_VECTOR_REGISTER(crossmp_vnodeops) is not used here since the vnode
143 * gets allocated early. See nameiinit for the direct call below.
146 struct nameicap_tracker {
148 TAILQ_ENTRY(nameicap_tracker) nm_link;
151 /* Zone for cap mode tracker elements used for dotdot capability checks. */
152 static uma_zone_t nt_zone;
155 nameiinit(void *dummy __unused)
158 namei_zone = uma_zcreate("NAMEI", MAXPATHLEN, NULL, NULL, NULL, NULL,
160 nt_zone = uma_zcreate("rentr", sizeof(struct nameicap_tracker),
161 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
162 vfs_vector_op_register(&crossmp_vnodeops);
163 getnewvnode("crossmp", NULL, &crossmp_vnodeops, &vp_crossmp);
165 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nameiinit, NULL);
167 static int lookup_cap_dotdot = 1;
168 SYSCTL_INT(_vfs, OID_AUTO, lookup_cap_dotdot, CTLFLAG_RWTUN,
169 &lookup_cap_dotdot, 0,
170 "enables \"..\" components in path lookup in capability mode");
171 static int lookup_cap_dotdot_nonlocal = 1;
172 SYSCTL_INT(_vfs, OID_AUTO, lookup_cap_dotdot_nonlocal, CTLFLAG_RWTUN,
173 &lookup_cap_dotdot_nonlocal, 0,
174 "enables \"..\" components in path lookup in capability mode "
175 "on non-local mount");
178 nameicap_tracker_add(struct nameidata *ndp, struct vnode *dp)
180 struct nameicap_tracker *nt;
182 if ((ndp->ni_lcf & NI_LCF_CAP_DOTDOT) == 0 || dp->v_type != VDIR)
184 if ((ndp->ni_lcf & (NI_LCF_BENEATH_ABS | NI_LCF_BENEATH_LATCHED)) ==
185 NI_LCF_BENEATH_ABS) {
186 MPASS((ndp->ni_lcf & NI_LCF_LATCH) != 0);
187 if (dp != ndp->ni_beneath_latch)
189 ndp->ni_lcf |= NI_LCF_BENEATH_LATCHED;
191 nt = uma_zalloc(nt_zone, M_WAITOK);
194 TAILQ_INSERT_TAIL(&ndp->ni_cap_tracker, nt, nm_link);
198 nameicap_cleanup(struct nameidata *ndp, bool clean_latch)
200 struct nameicap_tracker *nt, *nt1;
202 KASSERT(TAILQ_EMPTY(&ndp->ni_cap_tracker) ||
203 (ndp->ni_lcf & NI_LCF_CAP_DOTDOT) != 0, ("not strictrelative"));
204 TAILQ_FOREACH_SAFE(nt, &ndp->ni_cap_tracker, nm_link, nt1) {
205 TAILQ_REMOVE(&ndp->ni_cap_tracker, nt, nm_link);
207 uma_zfree(nt_zone, nt);
209 if (clean_latch && (ndp->ni_lcf & NI_LCF_LATCH) != 0) {
210 ndp->ni_lcf &= ~NI_LCF_LATCH;
211 vrele(ndp->ni_beneath_latch);
216 * For dotdot lookups in capability mode, only allow the component
217 * lookup to succeed if the resulting directory was already traversed
218 * during the operation. Also fail dotdot lookups for non-local
219 * filesystems, where external agents might assist local lookups to
220 * escape the compartment.
223 nameicap_check_dotdot(struct nameidata *ndp, struct vnode *dp)
225 struct nameicap_tracker *nt;
228 if ((ndp->ni_lcf & NI_LCF_CAP_DOTDOT) == 0 || dp == NULL ||
232 if (lookup_cap_dotdot_nonlocal == 0 && mp != NULL &&
233 (mp->mnt_flag & MNT_LOCAL) == 0)
234 return (ENOTCAPABLE);
235 TAILQ_FOREACH_REVERSE(nt, &ndp->ni_cap_tracker, nameicap_tracker_head,
240 if ((ndp->ni_lcf & NI_LCF_BENEATH_ABS) != 0) {
241 ndp->ni_lcf &= ~NI_LCF_BENEATH_LATCHED;
242 nameicap_cleanup(ndp, false);
245 return (ENOTCAPABLE);
249 namei_cleanup_cnp(struct componentname *cnp)
252 uma_zfree(namei_zone, cnp->cn_pnbuf);
254 cnp->cn_pnbuf = NULL;
255 cnp->cn_nameptr = NULL;
260 namei_handle_root(struct nameidata *ndp, struct vnode **dpp)
262 struct componentname *cnp;
265 if ((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) != 0) {
267 if (KTRPOINT(curthread, KTR_CAPFAIL))
268 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
270 return (ENOTCAPABLE);
272 if ((cnp->cn_flags & BENEATH) != 0) {
273 ndp->ni_lcf |= NI_LCF_BENEATH_ABS;
274 ndp->ni_lcf &= ~NI_LCF_BENEATH_LATCHED;
275 nameicap_cleanup(ndp, false);
277 while (*(cnp->cn_nameptr) == '/') {
281 *dpp = ndp->ni_rootdir;
287 namei_setup(struct nameidata *ndp, struct vnode **dpp, struct pwd **pwdp)
289 struct componentname *cnp;
294 struct filecaps dirfd_caps;
301 startdir_used = false;
305 #ifdef CAPABILITY_MODE
307 * In capability mode, lookups must be restricted to happen in
308 * the subtree with the root specified by the file descriptor:
309 * - The root must be real file descriptor, not the pseudo-descriptor
311 * - The passed path must be relative and not absolute.
312 * - If lookup_cap_dotdot is disabled, path must not contain the
314 * - If lookup_cap_dotdot is enabled, we verify that all '..'
315 * components lookups result in the directories which were
316 * previously walked by us, which prevents an escape from
319 if (IN_CAPABILITY_MODE(td) && (cnp->cn_flags & NOCAPCHECK) == 0) {
320 ndp->ni_lcf |= NI_LCF_STRICTRELATIVE;
321 if (ndp->ni_dirfd == AT_FDCWD) {
323 if (KTRPOINT(td, KTR_CAPFAIL))
324 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
333 * Get starting point for the translation.
337 * The reference on ni_rootdir is acquired in the block below to avoid
338 * back-to-back atomics for absolute lookups.
340 ndp->ni_rootdir = pwd->pwd_rdir;
341 ndp->ni_topdir = pwd->pwd_jdir;
343 if (cnp->cn_pnbuf[0] == '/') {
344 ndp->ni_resflags |= NIRES_ABS;
345 error = namei_handle_root(ndp, dpp);
347 if (ndp->ni_startdir != NULL) {
348 *dpp = ndp->ni_startdir;
349 startdir_used = true;
350 } else if (ndp->ni_dirfd == AT_FDCWD) {
351 *dpp = pwd->pwd_cdir;
354 rights = *ndp->ni_rightsneeded;
355 cap_rights_set_one(&rights, CAP_LOOKUP);
357 if (cnp->cn_flags & AUDITVNODE1)
358 AUDIT_ARG_ATFD1(ndp->ni_dirfd);
359 if (cnp->cn_flags & AUDITVNODE2)
360 AUDIT_ARG_ATFD2(ndp->ni_dirfd);
362 * Effectively inlined fgetvp_rights, because we need to
363 * inspect the file as well as grabbing the vnode.
365 error = fget_cap(td, ndp->ni_dirfd, &rights,
366 &dfp, &ndp->ni_filecaps);
369 * Preserve the error; it should either be EBADF
370 * or capability-related, both of which can be
371 * safely returned to the caller.
374 if (dfp->f_ops == &badfileops) {
376 } else if (dfp->f_vnode == NULL) {
382 if ((dfp->f_flag & FSEARCH) != 0)
383 cnp->cn_flags |= NOEXECCHECK;
389 * If file descriptor doesn't have all rights,
390 * all lookups relative to it must also be
394 if (!cap_rights_contains(&ndp->ni_filecaps.fc_rights,
396 ndp->ni_filecaps.fc_fcntls != CAP_FCNTL_ALL ||
397 ndp->ni_filecaps.fc_nioctls != -1) {
398 ndp->ni_lcf |= NI_LCF_STRICTRELATIVE;
402 if (error == 0 && (*dpp)->v_type != VDIR)
405 if (error == 0 && (cnp->cn_flags & BENEATH) != 0) {
406 if (ndp->ni_dirfd == AT_FDCWD) {
407 ndp->ni_beneath_latch = pwd->pwd_cdir;
408 vrefact(ndp->ni_beneath_latch);
410 rights = *ndp->ni_rightsneeded;
411 cap_rights_set_one(&rights, CAP_LOOKUP);
412 error = fgetvp_rights(td, ndp->ni_dirfd, &rights,
413 &dirfd_caps, &ndp->ni_beneath_latch);
414 if (error == 0 && (*dpp)->v_type != VDIR) {
415 vrele(ndp->ni_beneath_latch);
420 ndp->ni_lcf |= NI_LCF_LATCH;
423 * If we are auditing the kernel pathname, save the user pathname.
425 if (cnp->cn_flags & AUDITVNODE1)
426 AUDIT_ARG_UPATH1_VP(td, ndp->ni_rootdir, *dpp, cnp->cn_pnbuf);
427 if (cnp->cn_flags & AUDITVNODE2)
428 AUDIT_ARG_UPATH2_VP(td, ndp->ni_rootdir, *dpp, cnp->cn_pnbuf);
429 if (ndp->ni_startdir != NULL && !startdir_used)
430 vrele(ndp->ni_startdir);
436 MPASS((ndp->ni_lcf & (NI_LCF_BENEATH_ABS | NI_LCF_LATCH)) !=
438 if (((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) != 0 &&
439 lookup_cap_dotdot != 0) ||
440 ((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) == 0 &&
441 (cnp->cn_flags & BENEATH) != 0))
442 ndp->ni_lcf |= NI_LCF_CAP_DOTDOT;
443 SDT_PROBE4(vfs, namei, lookup, entry, *dpp, cnp->cn_pnbuf,
444 cnp->cn_flags, false);
450 * Convert a pathname into a pointer to a locked vnode.
452 * The FOLLOW flag is set when symbolic links are to be followed
453 * when they occur at the end of the name translation process.
454 * Symbolic links are always followed for all other pathname
455 * components other than the last.
457 * The segflg defines whether the name is to be copied from user
458 * space or kernel space.
460 * Overall outline of namei:
463 * get starting directory
464 * while (!done && !error) {
465 * call lookup to search path.
466 * if symbolic link, massage name in buffer and continue
470 namei(struct nameidata *ndp)
472 char *cp; /* pointer into pathname argument */
473 struct vnode *dp; /* the directory we are searching */
474 struct iovec aiov; /* uio for reading symbolic links */
475 struct componentname *cnp;
480 enum cache_fpl_status status;
484 ndp->ni_cnd.cn_cred = ndp->ni_cnd.cn_thread->td_ucred;
485 KASSERT(cnp->cn_cred && td->td_proc, ("namei: bad cred/proc"));
486 KASSERT((cnp->cn_nameiop & (~OPMASK)) == 0,
487 ("namei: nameiop contaminated with flags"));
488 KASSERT((cnp->cn_flags & OPMASK) == 0,
489 ("namei: flags contaminated with nameiops"));
490 KASSERT((cnp->cn_flags & NAMEI_INTERNAL_FLAGS) == 0,
491 ("namei: unexpected flags: %" PRIx64 "\n",
492 cnp->cn_flags & NAMEI_INTERNAL_FLAGS));
493 if (cnp->cn_flags & NOCACHE)
494 KASSERT(cnp->cn_nameiop != LOOKUP,
495 ("%s: NOCACHE passed with LOOKUP", __func__));
496 MPASS(ndp->ni_startdir == NULL || ndp->ni_startdir->v_type == VDIR ||
497 ndp->ni_startdir->v_type == VBAD);
503 * Get a buffer for the name to be translated, and copy the
504 * name into the buffer.
506 if ((cnp->cn_flags & HASBUF) == 0)
507 cnp->cn_pnbuf = uma_zalloc(namei_zone, M_WAITOK);
508 if (ndp->ni_segflg == UIO_SYSSPACE)
509 error = copystr(ndp->ni_dirp, cnp->cn_pnbuf, MAXPATHLEN,
512 error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf, MAXPATHLEN,
515 if (__predict_false(error != 0)) {
516 namei_cleanup_cnp(cnp);
521 * Don't allow empty pathnames.
523 if (__predict_false(*cnp->cn_pnbuf == '\0')) {
524 namei_cleanup_cnp(cnp);
529 if (KTRPOINT(td, KTR_NAMEI)) {
530 KASSERT(cnp->cn_thread == curthread,
531 ("namei not using curthread"));
532 ktrnamei(cnp->cn_pnbuf);
536 cnp->cn_nameptr = cnp->cn_pnbuf;
539 * First try looking up the target without locking any vnodes.
541 * We may need to start from scratch or pick up where it left off.
543 error = cache_fplookup(ndp, &status, &pwd);
545 case CACHE_FPL_STATUS_UNSET:
546 __assert_unreachable();
548 case CACHE_FPL_STATUS_HANDLED:
550 case CACHE_FPL_STATUS_PARTIAL:
551 TAILQ_INIT(&ndp->ni_cap_tracker);
552 dp = ndp->ni_startdir;
554 case CACHE_FPL_STATUS_ABORTED:
555 TAILQ_INIT(&ndp->ni_cap_tracker);
556 error = namei_setup(ndp, &dp, &pwd);
558 namei_cleanup_cnp(cnp);
570 ndp->ni_startdir = dp;
575 * If not a symbolic link, we're done.
577 if ((cnp->cn_flags & ISSYMLINK) == 0) {
578 if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) {
579 namei_cleanup_cnp(cnp);
581 cnp->cn_flags |= HASBUF;
582 if ((ndp->ni_lcf & (NI_LCF_BENEATH_ABS |
583 NI_LCF_BENEATH_LATCHED)) == NI_LCF_BENEATH_ABS) {
587 nameicap_cleanup(ndp, true);
588 SDT_PROBE3(vfs, namei, lookup, return, error,
589 (error == 0 ? ndp->ni_vp : NULL), false);
593 if (ndp->ni_loopcnt++ >= MAXSYMLINKS) {
598 if ((cnp->cn_flags & NOMACCHECK) == 0) {
599 error = mac_vnode_check_readlink(td->td_ucred,
605 if (ndp->ni_pathlen > 1)
606 cp = uma_zalloc(namei_zone, M_WAITOK);
610 aiov.iov_len = MAXPATHLEN;
611 auio.uio_iov = &aiov;
614 auio.uio_rw = UIO_READ;
615 auio.uio_segflg = UIO_SYSSPACE;
617 auio.uio_resid = MAXPATHLEN;
618 error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred);
620 if (ndp->ni_pathlen > 1)
621 uma_zfree(namei_zone, cp);
624 linklen = MAXPATHLEN - auio.uio_resid;
626 if (ndp->ni_pathlen > 1)
627 uma_zfree(namei_zone, cp);
631 if (linklen + ndp->ni_pathlen > MAXPATHLEN) {
632 if (ndp->ni_pathlen > 1)
633 uma_zfree(namei_zone, cp);
634 error = ENAMETOOLONG;
637 if (ndp->ni_pathlen > 1) {
638 bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen);
639 uma_zfree(namei_zone, cnp->cn_pnbuf);
642 cnp->cn_pnbuf[linklen] = '\0';
643 ndp->ni_pathlen += linklen;
647 * Check if root directory should replace current directory.
649 cnp->cn_nameptr = cnp->cn_pnbuf;
650 if (*(cnp->cn_nameptr) == '/') {
652 error = namei_handle_root(ndp, &dp);
662 namei_cleanup_cnp(cnp);
663 nameicap_cleanup(ndp, true);
664 SDT_PROBE3(vfs, namei, lookup, return, error, NULL, false);
670 compute_cn_lkflags(struct mount *mp, int lkflags, int cnflags)
673 if (mp == NULL || ((lkflags & LK_SHARED) &&
674 (!(mp->mnt_kern_flag & MNTK_LOOKUP_SHARED) ||
675 ((cnflags & ISDOTDOT) &&
676 (mp->mnt_kern_flag & MNTK_LOOKUP_EXCL_DOTDOT))))) {
677 lkflags &= ~LK_SHARED;
678 lkflags |= LK_EXCLUSIVE;
680 lkflags |= LK_NODDLKTREAT;
685 needs_exclusive_leaf(struct mount *mp, int flags)
689 * Intermediate nodes can use shared locks, we only need to
690 * force an exclusive lock for leaf nodes.
692 if ((flags & (ISLASTCN | LOCKLEAF)) != (ISLASTCN | LOCKLEAF))
695 /* Always use exclusive locks if LOCKSHARED isn't set. */
696 if (!(flags & LOCKSHARED))
700 * For lookups during open(), if the mount point supports
701 * extended shared operations, then use a shared lock for the
702 * leaf node, otherwise use an exclusive lock.
704 if ((flags & ISOPEN) != 0)
705 return (!MNT_EXTENDED_SHARED(mp));
708 * Lookup requests outside of open() that specify LOCKSHARED
709 * only need a shared lock on the leaf vnode.
716 * This is a very central and rather complicated routine.
718 * The pathname is pointed to by ni_ptr and is of length ni_pathlen.
719 * The starting directory is taken from ni_startdir. The pathname is
720 * descended until done, or a symbolic link is encountered. The variable
721 * ni_more is clear if the path is completed; it is set to one if a
722 * symbolic link needing interpretation is encountered.
724 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on
725 * whether the name is to be looked up, created, renamed, or deleted.
726 * When CREATE, RENAME, or DELETE is specified, information usable in
727 * creating, renaming, or deleting a directory entry may be calculated.
728 * If flag has LOCKPARENT or'ed into it, the parent directory is returned
729 * locked. If flag has WANTPARENT or'ed into it, the parent directory is
730 * returned unlocked. Otherwise the parent directory is not returned. If
731 * the target of the pathname exists and LOCKLEAF is or'ed into the flag
732 * the target is returned locked, otherwise it is returned unlocked.
733 * When creating or renaming and LOCKPARENT is specified, the target may not
734 * be ".". When deleting and LOCKPARENT is specified, the target may be ".".
736 * Overall outline of lookup:
739 * identify next component of name at ndp->ni_ptr
740 * handle degenerate case where name is null string
741 * if .. and crossing mount points and on mounted filesys, find parent
742 * call VOP_LOOKUP routine for next component name
743 * directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set
744 * component vnode returned in ni_vp (if it exists), locked.
745 * if result vnode is mounted on and crossing mount points,
746 * find mounted on vnode
747 * if more components of name, do next level at dirloop
748 * return the answer in ni_vp, locked if LOCKLEAF set
749 * if LOCKPARENT set, return locked parent in ni_dvp
750 * if WANTPARENT set, return unlocked parent in ni_dvp
753 lookup(struct nameidata *ndp)
755 char *cp; /* pointer into pathname argument */
756 char *prev_ni_next; /* saved ndp->ni_next */
757 struct vnode *dp = NULL; /* the directory we are searching */
758 struct vnode *tdp; /* saved dp */
759 struct mount *mp; /* mount table entry */
761 size_t prev_ni_pathlen; /* saved ndp->ni_pathlen */
762 int docache; /* == 0 do not cache last component */
763 int wantparent; /* 1 => wantparent or lockparent flag */
764 int rdonly; /* lookup read-only flag bit */
766 int dpunlocked = 0; /* dp has already been unlocked */
767 int relookup = 0; /* do not consume the path component */
768 struct componentname *cnp = &ndp->ni_cnd;
773 * Setup: break out flag bits into variables.
776 wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT);
777 KASSERT(cnp->cn_nameiop == LOOKUP || wantparent,
778 ("CREATE, DELETE, RENAME require LOCKPARENT or WANTPARENT."));
779 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE;
780 if (cnp->cn_nameiop == DELETE ||
781 (wantparent && cnp->cn_nameiop != CREATE &&
782 cnp->cn_nameiop != LOOKUP))
784 rdonly = cnp->cn_flags & RDONLY;
785 cnp->cn_flags &= ~ISSYMLINK;
788 * We use shared locks until we hit the parent of the last cn then
789 * we adjust based on the requesting flags.
791 cnp->cn_lkflags = LK_SHARED;
792 dp = ndp->ni_startdir;
793 ndp->ni_startdir = NULLVP;
795 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | LK_RETRY,
800 * Search a new directory.
802 * The last component of the filename is left accessible via
803 * cnp->cn_nameptr for callers that need the name. Callers needing
804 * the name set the SAVENAME flag. When done, they assume
805 * responsibility for freeing the pathname buffer.
807 for (cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++)
809 cnp->cn_namelen = cp - cnp->cn_nameptr;
810 if (cnp->cn_namelen > NAME_MAX) {
811 error = ENAMETOOLONG;
814 #ifdef NAMEI_DIAGNOSTIC
817 printf("{%s}: ", cnp->cn_nameptr);
820 prev_ni_pathlen = ndp->ni_pathlen;
821 ndp->ni_pathlen -= cnp->cn_namelen;
822 KASSERT(ndp->ni_pathlen <= PATH_MAX,
823 ("%s: ni_pathlen underflow to %zd\n", __func__, ndp->ni_pathlen));
824 prev_ni_next = ndp->ni_next;
828 * Replace multiple slashes by a single slash and trailing slashes
829 * by a null. This must be done before VOP_LOOKUP() because some
830 * fs's don't know about trailing slashes. Remember if there were
831 * trailing slashes to handle symlinks, existing non-directories
832 * and non-existing files that won't be directories specially later.
834 while (*cp == '/' && (cp[1] == '/' || cp[1] == '\0')) {
838 *ndp->ni_next = '\0';
839 cnp->cn_flags |= TRAILINGSLASH;
844 cnp->cn_flags |= MAKEENTRY;
845 if (*cp == '\0' && docache == 0)
846 cnp->cn_flags &= ~MAKEENTRY;
847 if (cnp->cn_namelen == 2 &&
848 cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.')
849 cnp->cn_flags |= ISDOTDOT;
851 cnp->cn_flags &= ~ISDOTDOT;
852 if (*ndp->ni_next == 0)
853 cnp->cn_flags |= ISLASTCN;
855 cnp->cn_flags &= ~ISLASTCN;
857 if ((cnp->cn_flags & ISLASTCN) != 0 &&
858 cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.' &&
859 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
864 nameicap_tracker_add(ndp, dp);
867 * Check for degenerate name (e.g. / or "")
868 * which is a way of talking about a directory,
869 * e.g. like "/." or ".".
871 if (cnp->cn_nameptr[0] == '\0') {
872 if (dp->v_type != VDIR) {
876 if (cnp->cn_nameiop != LOOKUP) {
886 if (cnp->cn_flags & AUDITVNODE1)
887 AUDIT_ARG_VNODE1(dp);
888 else if (cnp->cn_flags & AUDITVNODE2)
889 AUDIT_ARG_VNODE2(dp);
891 if (!(cnp->cn_flags & (LOCKPARENT | LOCKLEAF)))
893 /* XXX This should probably move to the top of function. */
894 if (cnp->cn_flags & SAVESTART)
895 panic("lookup: SAVESTART");
900 * Handle "..": five special cases.
901 * 0. If doing a capability lookup and lookup_cap_dotdot is
902 * disabled, return ENOTCAPABLE.
903 * 1. Return an error if this is the last component of
904 * the name and the operation is DELETE or RENAME.
905 * 2. If at root directory (e.g. after chroot)
906 * or at absolute root directory
907 * then ignore it so can't get out.
908 * 3. If this vnode is the root of a mounted
909 * filesystem, then replace it with the
910 * vnode which was mounted on so we take the
911 * .. in the other filesystem.
912 * 4. If the vnode is the top directory of
913 * the jail or chroot, don't let them out.
914 * 5. If doing a capability lookup and lookup_cap_dotdot is
915 * enabled, return ENOTCAPABLE if the lookup would escape
916 * from the initial file descriptor directory. Checks are
917 * done by ensuring that namei() already traversed the
918 * result of dotdot lookup.
920 if (cnp->cn_flags & ISDOTDOT) {
921 if ((ndp->ni_lcf & (NI_LCF_STRICTRELATIVE | NI_LCF_CAP_DOTDOT))
922 == NI_LCF_STRICTRELATIVE) {
924 if (KTRPOINT(curthread, KTR_CAPFAIL))
925 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
930 if ((cnp->cn_flags & ISLASTCN) != 0 &&
931 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
936 for (pr = cnp->cn_cred->cr_prison; pr != NULL;
938 if (dp == pr->pr_root)
940 if (dp == ndp->ni_rootdir ||
941 dp == ndp->ni_topdir ||
944 ((dp->v_vflag & VV_ROOT) != 0 &&
945 (cnp->cn_flags & NOCROSSMOUNT) != 0)) {
951 if ((dp->v_vflag & VV_ROOT) == 0)
953 if (VN_IS_DOOMED(dp)) { /* forced unmount */
958 dp = dp->v_mount->mnt_vnodecovered;
962 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags |
963 LK_RETRY, ISDOTDOT));
964 error = nameicap_check_dotdot(ndp, dp);
967 if (KTRPOINT(curthread, KTR_CAPFAIL))
968 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
976 * We now have a segment name to search for, and a directory to search.
980 error = mac_vnode_check_lookup(cnp->cn_thread->td_ucred, dp, cnp);
986 ASSERT_VOP_LOCKED(dp, "lookup");
988 * If we have a shared lock we may need to upgrade the lock for the
991 if ((cnp->cn_flags & LOCKPARENT) && (cnp->cn_flags & ISLASTCN) &&
992 dp != vp_crossmp && VOP_ISLOCKED(dp) == LK_SHARED)
993 vn_lock(dp, LK_UPGRADE|LK_RETRY);
994 if (VN_IS_DOOMED(dp)) {
999 * If we're looking up the last component and we need an exclusive
1000 * lock, adjust our lkflags.
1002 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags))
1003 cnp->cn_lkflags = LK_EXCLUSIVE;
1004 #ifdef NAMEI_DIAGNOSTIC
1005 vn_printf(dp, "lookup in ");
1007 lkflags_save = cnp->cn_lkflags;
1008 cnp->cn_lkflags = compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags,
1010 error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp);
1011 cnp->cn_lkflags = lkflags_save;
1013 KASSERT(ndp->ni_vp == NULL, ("leaf should be empty"));
1014 #ifdef NAMEI_DIAGNOSTIC
1015 printf("not found\n");
1017 if ((error == ENOENT) &&
1018 (dp->v_vflag & VV_ROOT) && (dp->v_mount != NULL) &&
1019 (dp->v_mount->mnt_flag & MNT_UNION)) {
1021 dp = dp->v_mount->mnt_vnodecovered;
1025 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags |
1026 LK_RETRY, cnp->cn_flags));
1027 nameicap_tracker_add(ndp, dp);
1031 if (error == ERELOOKUP) {
1039 if (error != EJUSTRETURN)
1042 * At this point, we know we're at the end of the
1043 * pathname. If creating / renaming, we can consider
1044 * allowing the file or directory to be created / renamed,
1045 * provided we're not on a read-only filesystem.
1051 /* trailing slash only allowed for directories */
1052 if ((cnp->cn_flags & TRAILINGSLASH) &&
1053 !(cnp->cn_flags & WILLBEDIR)) {
1057 if ((cnp->cn_flags & LOCKPARENT) == 0)
1060 * We return with ni_vp NULL to indicate that the entry
1061 * doesn't currently exist, leaving a pointer to the
1062 * (possibly locked) directory vnode in ndp->ni_dvp.
1064 if (cnp->cn_flags & SAVESTART) {
1065 ndp->ni_startdir = ndp->ni_dvp;
1066 VREF(ndp->ni_startdir);
1072 #ifdef NAMEI_DIAGNOSTIC
1078 * Check to see if the vnode has been mounted on;
1079 * if so find the root of the mounted filesystem.
1081 while (dp->v_type == VDIR && (mp = dp->v_mountedhere) &&
1082 (cnp->cn_flags & NOCROSSMOUNT) == 0) {
1083 if (vfs_busy(mp, 0))
1086 if (dp != ndp->ni_dvp)
1090 vrefact(vp_crossmp);
1091 ndp->ni_dvp = vp_crossmp;
1092 error = VFS_ROOT(mp, compute_cn_lkflags(mp, cnp->cn_lkflags,
1093 cnp->cn_flags), &tdp);
1095 if (vn_lock(vp_crossmp, LK_SHARED | LK_NOWAIT))
1096 panic("vp_crossmp exclusively locked or reclaimed");
1101 ndp->ni_vp = dp = tdp;
1105 * Check for symbolic link
1107 if ((dp->v_type == VLNK) &&
1108 ((cnp->cn_flags & FOLLOW) || (cnp->cn_flags & TRAILINGSLASH) ||
1109 *ndp->ni_next == '/')) {
1110 cnp->cn_flags |= ISSYMLINK;
1111 if (VN_IS_DOOMED(dp)) {
1113 * We can't know whether the directory was mounted with
1114 * NOSYMFOLLOW, so we can't follow safely.
1119 if (dp->v_mount->mnt_flag & MNT_NOSYMFOLLOW) {
1124 * Symlink code always expects an unlocked dvp.
1126 if (ndp->ni_dvp != ndp->ni_vp) {
1127 VOP_UNLOCK(ndp->ni_dvp);
1128 ni_dvp_unlocked = 1;
1135 * Not a symbolic link that we will follow. Continue with the
1136 * next component if there is any; otherwise, we're done.
1138 KASSERT((cnp->cn_flags & ISLASTCN) || *ndp->ni_next == '/',
1139 ("lookup: invalid path state."));
1142 ndp->ni_pathlen = prev_ni_pathlen;
1143 ndp->ni_next = prev_ni_next;
1144 if (ndp->ni_dvp != dp)
1150 if (cnp->cn_flags & ISDOTDOT) {
1151 error = nameicap_check_dotdot(ndp, ndp->ni_vp);
1154 if (KTRPOINT(curthread, KTR_CAPFAIL))
1155 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
1160 if (*ndp->ni_next == '/') {
1161 cnp->cn_nameptr = ndp->ni_next;
1162 while (*cnp->cn_nameptr == '/') {
1166 if (ndp->ni_dvp != dp)
1173 * If we're processing a path with a trailing slash,
1174 * check that the end result is a directory.
1176 if ((cnp->cn_flags & TRAILINGSLASH) && dp->v_type != VDIR) {
1181 * Disallow directory write attempts on read-only filesystems.
1184 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
1188 if (cnp->cn_flags & SAVESTART) {
1189 ndp->ni_startdir = ndp->ni_dvp;
1190 VREF(ndp->ni_startdir);
1193 ni_dvp_unlocked = 2;
1194 if (ndp->ni_dvp != dp)
1198 } else if ((cnp->cn_flags & LOCKPARENT) == 0 && ndp->ni_dvp != dp) {
1199 VOP_UNLOCK(ndp->ni_dvp);
1200 ni_dvp_unlocked = 1;
1203 if (cnp->cn_flags & AUDITVNODE1)
1204 AUDIT_ARG_VNODE1(dp);
1205 else if (cnp->cn_flags & AUDITVNODE2)
1206 AUDIT_ARG_VNODE2(dp);
1208 if ((cnp->cn_flags & LOCKLEAF) == 0)
1212 * Because of shared lookup we may have the vnode shared locked, but
1213 * the caller may want it to be exclusively locked.
1215 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags) &&
1216 VOP_ISLOCKED(dp) != LK_EXCLUSIVE) {
1217 vn_lock(dp, LK_UPGRADE | LK_RETRY);
1218 if (VN_IS_DOOMED(dp)) {
1226 if (ni_dvp_unlocked != 2) {
1227 if (dp != ndp->ni_dvp && !ni_dvp_unlocked)
1240 * relookup - lookup a path name component
1241 * Used by lookup to re-acquire things.
1244 relookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp)
1246 struct vnode *dp = NULL; /* the directory we are searching */
1247 int wantparent; /* 1 => wantparent or lockparent flag */
1248 int rdonly; /* lookup read-only flag bit */
1251 KASSERT(cnp->cn_flags & ISLASTCN,
1252 ("relookup: Not given last component."));
1254 * Setup: break out flag bits into variables.
1256 wantparent = cnp->cn_flags & (LOCKPARENT|WANTPARENT);
1257 KASSERT(wantparent, ("relookup: parent not wanted."));
1258 rdonly = cnp->cn_flags & RDONLY;
1259 cnp->cn_flags &= ~ISSYMLINK;
1261 cnp->cn_lkflags = LK_EXCLUSIVE;
1262 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY);
1265 * Search a new directory.
1267 * The last component of the filename is left accessible via
1268 * cnp->cn_nameptr for callers that need the name. Callers needing
1269 * the name set the SAVENAME flag. When done, they assume
1270 * responsibility for freeing the pathname buffer.
1272 #ifdef NAMEI_DIAGNOSTIC
1273 printf("{%s}: ", cnp->cn_nameptr);
1277 * Check for "" which represents the root directory after slash
1280 if (cnp->cn_nameptr[0] == '\0') {
1282 * Support only LOOKUP for "/" because lookup()
1283 * can't succeed for CREATE, DELETE and RENAME.
1285 KASSERT(cnp->cn_nameiop == LOOKUP, ("nameiop must be LOOKUP"));
1286 KASSERT(dp->v_type == VDIR, ("dp is not a directory"));
1288 if (!(cnp->cn_flags & LOCKLEAF))
1291 /* XXX This should probably move to the top of function. */
1292 if (cnp->cn_flags & SAVESTART)
1293 panic("lookup: SAVESTART");
1297 if (cnp->cn_flags & ISDOTDOT)
1298 panic ("relookup: lookup on dot-dot");
1301 * We now have a segment name to search for, and a directory to search.
1303 #ifdef NAMEI_DIAGNOSTIC
1304 vn_printf(dp, "search in ");
1306 if ((error = VOP_LOOKUP(dp, vpp, cnp)) != 0) {
1307 KASSERT(*vpp == NULL, ("leaf should be empty"));
1308 if (error != EJUSTRETURN)
1311 * If creating and at end of pathname, then can consider
1312 * allowing file to be created.
1318 /* ASSERT(dvp == ndp->ni_startdir) */
1319 if (cnp->cn_flags & SAVESTART)
1321 if ((cnp->cn_flags & LOCKPARENT) == 0)
1324 * We return with ni_vp NULL to indicate that the entry
1325 * doesn't currently exist, leaving a pointer to the
1326 * (possibly locked) directory vnode in ndp->ni_dvp.
1334 * Disallow directory write attempts on read-only filesystems.
1337 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
1346 * Set the parent lock/ref state to the requested state.
1348 if ((cnp->cn_flags & LOCKPARENT) == 0 && dvp != dp) {
1353 } else if (!wantparent)
1356 * Check for symbolic link
1358 KASSERT(dp->v_type != VLNK || !(cnp->cn_flags & FOLLOW),
1359 ("relookup: symlink found.\n"));
1361 /* ASSERT(dvp == ndp->ni_startdir) */
1362 if (cnp->cn_flags & SAVESTART)
1365 if ((cnp->cn_flags & LOCKLEAF) == 0)
1375 * Free data allocated by namei(); see namei(9) for details.
1378 NDFREE_PNBUF(struct nameidata *ndp)
1381 if ((ndp->ni_cnd.cn_flags & HASBUF) != 0) {
1382 uma_zfree(namei_zone, ndp->ni_cnd.cn_pnbuf);
1383 ndp->ni_cnd.cn_flags &= ~HASBUF;
1388 (NDFREE)(struct nameidata *ndp, const u_int flags)
1396 if (!(flags & NDF_NO_FREE_PNBUF)) {
1399 if (!(flags & NDF_NO_VP_UNLOCK) &&
1400 (ndp->ni_cnd.cn_flags & LOCKLEAF) && ndp->ni_vp)
1402 if (!(flags & NDF_NO_DVP_UNLOCK) &&
1403 (ndp->ni_cnd.cn_flags & LOCKPARENT) &&
1404 ndp->ni_dvp != ndp->ni_vp)
1406 if (!(flags & NDF_NO_VP_RELE) && ndp->ni_vp) {
1415 VOP_UNLOCK(ndp->ni_vp);
1416 if (!(flags & NDF_NO_DVP_RELE) &&
1417 (ndp->ni_cnd.cn_flags & (LOCKPARENT|WANTPARENT))) {
1426 VOP_UNLOCK(ndp->ni_dvp);
1427 if (!(flags & NDF_NO_STARTDIR_RELE) &&
1428 (ndp->ni_cnd.cn_flags & SAVESTART)) {
1429 vrele(ndp->ni_startdir);
1430 ndp->ni_startdir = NULL;
1435 * Determine if there is a suitable alternate filename under the specified
1436 * prefix for the specified path. If the create flag is set, then the
1437 * alternate prefix will be used so long as the parent directory exists.
1438 * This is used by the various compatibility ABIs so that Linux binaries prefer
1439 * files under /compat/linux for example. The chosen path (whether under
1440 * the prefix or under /) is returned in a kernel malloc'd buffer pointed
1441 * to by pathbuf. The caller is responsible for free'ing the buffer from
1442 * the M_TEMP bucket if one is returned.
1445 kern_alternate_path(struct thread *td, const char *prefix, const char *path,
1446 enum uio_seg pathseg, char **pathbuf, int create, int dirfd)
1448 struct nameidata nd, ndroot;
1449 char *ptr, *buf, *cp;
1453 buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
1456 /* Copy the prefix into the new pathname as a starting point. */
1457 len = strlcpy(buf, prefix, MAXPATHLEN);
1458 if (len >= MAXPATHLEN) {
1463 sz = MAXPATHLEN - len;
1466 /* Append the filename to the prefix. */
1467 if (pathseg == UIO_SYSSPACE)
1468 error = copystr(path, ptr, sz, &len);
1470 error = copyinstr(path, ptr, sz, &len);
1478 /* Only use a prefix with absolute pathnames. */
1484 if (dirfd != AT_FDCWD) {
1486 * We want the original because the "prefix" is
1487 * included in the already opened dirfd.
1489 bcopy(ptr, buf, len);
1494 * We know that there is a / somewhere in this pathname.
1495 * Search backwards for it, to find the file's parent dir
1496 * to see if it exists in the alternate tree. If it does,
1497 * and we want to create a file (cflag is set). We don't
1498 * need to worry about the root comparison in this case.
1502 for (cp = &ptr[len] - 1; *cp != '/'; cp--);
1505 NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_SYSSPACE, buf, td);
1511 NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_SYSSPACE, buf, td);
1518 * We now compare the vnode of the prefix to the one
1519 * vnode asked. If they resolve to be the same, then we
1520 * ignore the match so that the real root gets used.
1521 * This avoids the problem of traversing "../.." to find the
1522 * root directory and never finding it, because "/" resolves
1523 * to the emulation root directory. This is expensive :-(
1525 NDINIT(&ndroot, LOOKUP, FOLLOW, UIO_SYSSPACE, prefix,
1528 /* We shouldn't ever get an error from this namei(). */
1529 error = namei(&ndroot);
1531 if (nd.ni_vp == ndroot.ni_vp)
1534 NDFREE(&ndroot, NDF_ONLY_PNBUF);
1535 vrele(ndroot.ni_vp);
1539 NDFREE(&nd, NDF_ONLY_PNBUF);
1543 /* If there was an error, use the original path name. */
1545 bcopy(ptr, buf, len);