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. This catches situations where already
219 * traversed directory is moved to different parent, and then we walk
220 * over it with dotdots.
222 * Also allow to force failure of dotdot lookups for non-local
223 * filesystems, where external agents might assist local lookups to
224 * escape the compartment.
227 nameicap_check_dotdot(struct nameidata *ndp, struct vnode *dp)
229 struct nameicap_tracker *nt;
232 if ((ndp->ni_lcf & NI_LCF_CAP_DOTDOT) == 0 || dp == NULL ||
236 if (lookup_cap_dotdot_nonlocal == 0 && mp != NULL &&
237 (mp->mnt_flag & MNT_LOCAL) == 0)
238 return (ENOTCAPABLE);
239 TAILQ_FOREACH_REVERSE(nt, &ndp->ni_cap_tracker, nameicap_tracker_head,
244 if ((ndp->ni_lcf & NI_LCF_BENEATH_ABS) != 0) {
245 ndp->ni_lcf &= ~NI_LCF_BENEATH_LATCHED;
246 nameicap_cleanup(ndp, false);
249 return (ENOTCAPABLE);
253 namei_cleanup_cnp(struct componentname *cnp)
256 uma_zfree(namei_zone, cnp->cn_pnbuf);
258 cnp->cn_pnbuf = NULL;
259 cnp->cn_nameptr = NULL;
264 namei_handle_root(struct nameidata *ndp, struct vnode **dpp)
266 struct componentname *cnp;
269 if ((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) != 0) {
271 if (KTRPOINT(curthread, KTR_CAPFAIL))
272 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
274 return (ENOTCAPABLE);
276 if ((cnp->cn_flags & BENEATH) != 0) {
277 ndp->ni_lcf |= NI_LCF_BENEATH_ABS;
278 ndp->ni_lcf &= ~NI_LCF_BENEATH_LATCHED;
279 nameicap_cleanup(ndp, false);
281 while (*(cnp->cn_nameptr) == '/') {
285 *dpp = ndp->ni_rootdir;
291 namei_setup(struct nameidata *ndp, struct vnode **dpp, struct pwd **pwdp)
293 struct componentname *cnp;
298 struct filecaps dirfd_caps;
305 startdir_used = false;
309 #ifdef CAPABILITY_MODE
311 * In capability mode, lookups must be restricted to happen in
312 * the subtree with the root specified by the file descriptor:
313 * - The root must be real file descriptor, not the pseudo-descriptor
315 * - The passed path must be relative and not absolute.
316 * - If lookup_cap_dotdot is disabled, path must not contain the
318 * - If lookup_cap_dotdot is enabled, we verify that all '..'
319 * components lookups result in the directories which were
320 * previously walked by us, which prevents an escape from
323 if (IN_CAPABILITY_MODE(td) && (cnp->cn_flags & NOCAPCHECK) == 0) {
324 ndp->ni_lcf |= NI_LCF_STRICTRELATIVE;
325 if (ndp->ni_dirfd == AT_FDCWD) {
327 if (KTRPOINT(td, KTR_CAPFAIL))
328 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
337 * Get starting point for the translation.
341 * The reference on ni_rootdir is acquired in the block below to avoid
342 * back-to-back atomics for absolute lookups.
344 ndp->ni_rootdir = pwd->pwd_rdir;
345 ndp->ni_topdir = pwd->pwd_jdir;
347 if (cnp->cn_pnbuf[0] == '/') {
348 ndp->ni_resflags |= NIRES_ABS;
349 error = namei_handle_root(ndp, dpp);
351 if (ndp->ni_startdir != NULL) {
352 *dpp = ndp->ni_startdir;
353 startdir_used = true;
354 } else if (ndp->ni_dirfd == AT_FDCWD) {
355 *dpp = pwd->pwd_cdir;
358 rights = *ndp->ni_rightsneeded;
359 cap_rights_set_one(&rights, CAP_LOOKUP);
361 if (cnp->cn_flags & AUDITVNODE1)
362 AUDIT_ARG_ATFD1(ndp->ni_dirfd);
363 if (cnp->cn_flags & AUDITVNODE2)
364 AUDIT_ARG_ATFD2(ndp->ni_dirfd);
366 * Effectively inlined fgetvp_rights, because we need to
367 * inspect the file as well as grabbing the vnode.
369 error = fget_cap(td, ndp->ni_dirfd, &rights,
370 &dfp, &ndp->ni_filecaps);
373 * Preserve the error; it should either be EBADF
374 * or capability-related, both of which can be
375 * safely returned to the caller.
378 if (dfp->f_ops == &badfileops) {
380 } else if (dfp->f_vnode == NULL) {
386 if ((dfp->f_flag & FSEARCH) != 0)
387 cnp->cn_flags |= NOEXECCHECK;
393 * If file descriptor doesn't have all rights,
394 * all lookups relative to it must also be
398 if (!cap_rights_contains(&ndp->ni_filecaps.fc_rights,
400 ndp->ni_filecaps.fc_fcntls != CAP_FCNTL_ALL ||
401 ndp->ni_filecaps.fc_nioctls != -1) {
402 ndp->ni_lcf |= NI_LCF_STRICTRELATIVE;
406 if (error == 0 && (*dpp)->v_type != VDIR)
409 if (error == 0 && (cnp->cn_flags & BENEATH) != 0) {
410 if (ndp->ni_dirfd == AT_FDCWD) {
411 ndp->ni_beneath_latch = pwd->pwd_cdir;
412 vrefact(ndp->ni_beneath_latch);
414 rights = *ndp->ni_rightsneeded;
415 cap_rights_set_one(&rights, CAP_LOOKUP);
416 error = fgetvp_rights(td, ndp->ni_dirfd, &rights,
417 &dirfd_caps, &ndp->ni_beneath_latch);
418 if (error == 0 && (*dpp)->v_type != VDIR) {
419 vrele(ndp->ni_beneath_latch);
424 ndp->ni_lcf |= NI_LCF_LATCH;
427 * If we are auditing the kernel pathname, save the user pathname.
429 if (cnp->cn_flags & AUDITVNODE1)
430 AUDIT_ARG_UPATH1_VP(td, ndp->ni_rootdir, *dpp, cnp->cn_pnbuf);
431 if (cnp->cn_flags & AUDITVNODE2)
432 AUDIT_ARG_UPATH2_VP(td, ndp->ni_rootdir, *dpp, cnp->cn_pnbuf);
433 if (ndp->ni_startdir != NULL && !startdir_used)
434 vrele(ndp->ni_startdir);
441 MPASS((ndp->ni_lcf & (NI_LCF_BENEATH_ABS | NI_LCF_LATCH)) !=
443 if (((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) != 0 &&
444 lookup_cap_dotdot != 0) ||
445 ((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) == 0 &&
446 (cnp->cn_flags & BENEATH) != 0))
447 ndp->ni_lcf |= NI_LCF_CAP_DOTDOT;
448 SDT_PROBE4(vfs, namei, lookup, entry, *dpp, cnp->cn_pnbuf,
449 cnp->cn_flags, false);
455 * Convert a pathname into a pointer to a locked vnode.
457 * The FOLLOW flag is set when symbolic links are to be followed
458 * when they occur at the end of the name translation process.
459 * Symbolic links are always followed for all other pathname
460 * components other than the last.
462 * The segflg defines whether the name is to be copied from user
463 * space or kernel space.
465 * Overall outline of namei:
468 * get starting directory
469 * while (!done && !error) {
470 * call lookup to search path.
471 * if symbolic link, massage name in buffer and continue
475 namei(struct nameidata *ndp)
477 char *cp; /* pointer into pathname argument */
478 struct vnode *dp; /* the directory we are searching */
479 struct iovec aiov; /* uio for reading symbolic links */
480 struct componentname *cnp;
485 enum cache_fpl_status status;
493 * While NDINIT may seem like a more natural place to do it, there are
494 * callers which directly modify flags past invoking init.
496 cnp->cn_origflags = cnp->cn_flags;
498 ndp->ni_cnd.cn_cred = ndp->ni_cnd.cn_thread->td_ucred;
499 KASSERT(cnp->cn_cred && td->td_proc, ("namei: bad cred/proc"));
500 KASSERT((cnp->cn_flags & NAMEI_INTERNAL_FLAGS) == 0,
501 ("namei: unexpected flags: %" PRIx64 "\n",
502 cnp->cn_flags & NAMEI_INTERNAL_FLAGS));
503 if (cnp->cn_flags & NOCACHE)
504 KASSERT(cnp->cn_nameiop != LOOKUP,
505 ("%s: NOCACHE passed with LOOKUP", __func__));
506 MPASS(ndp->ni_startdir == NULL || ndp->ni_startdir->v_type == VDIR ||
507 ndp->ni_startdir->v_type == VBAD);
513 * Get a buffer for the name to be translated, and copy the
514 * name into the buffer.
516 cnp->cn_pnbuf = uma_zalloc(namei_zone, M_WAITOK);
517 if (ndp->ni_segflg == UIO_SYSSPACE)
518 error = copystr(ndp->ni_dirp, cnp->cn_pnbuf, MAXPATHLEN,
521 error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf, MAXPATHLEN,
524 if (__predict_false(error != 0)) {
525 namei_cleanup_cnp(cnp);
530 * Don't allow empty pathnames.
532 if (__predict_false(*cnp->cn_pnbuf == '\0')) {
533 namei_cleanup_cnp(cnp);
538 if (KTRPOINT(td, KTR_NAMEI)) {
539 KASSERT(cnp->cn_thread == curthread,
540 ("namei not using curthread"));
541 ktrnamei(cnp->cn_pnbuf);
545 cnp->cn_nameptr = cnp->cn_pnbuf;
548 * First try looking up the target without locking any vnodes.
550 * We may need to start from scratch or pick up where it left off.
552 error = cache_fplookup(ndp, &status, &pwd);
554 case CACHE_FPL_STATUS_UNSET:
555 __assert_unreachable();
557 case CACHE_FPL_STATUS_HANDLED:
561 case CACHE_FPL_STATUS_PARTIAL:
562 TAILQ_INIT(&ndp->ni_cap_tracker);
563 dp = ndp->ni_startdir;
565 case CACHE_FPL_STATUS_ABORTED:
566 TAILQ_INIT(&ndp->ni_cap_tracker);
567 error = namei_setup(ndp, &dp, &pwd);
569 namei_cleanup_cnp(cnp);
581 ndp->ni_startdir = dp;
586 * If not a symbolic link, we're done.
588 if ((cnp->cn_flags & ISSYMLINK) == 0) {
589 if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) {
590 namei_cleanup_cnp(cnp);
592 cnp->cn_flags |= HASBUF;
593 if ((ndp->ni_lcf & (NI_LCF_BENEATH_ABS |
594 NI_LCF_BENEATH_LATCHED)) == NI_LCF_BENEATH_ABS) {
598 nameicap_cleanup(ndp, true);
599 SDT_PROBE3(vfs, namei, lookup, return, error,
600 (error == 0 ? ndp->ni_vp : NULL), false);
606 if (ndp->ni_loopcnt++ >= MAXSYMLINKS) {
611 if ((cnp->cn_flags & NOMACCHECK) == 0) {
612 error = mac_vnode_check_readlink(td->td_ucred,
618 if (ndp->ni_pathlen > 1)
619 cp = uma_zalloc(namei_zone, M_WAITOK);
623 aiov.iov_len = MAXPATHLEN;
624 auio.uio_iov = &aiov;
627 auio.uio_rw = UIO_READ;
628 auio.uio_segflg = UIO_SYSSPACE;
630 auio.uio_resid = MAXPATHLEN;
631 error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred);
633 if (ndp->ni_pathlen > 1)
634 uma_zfree(namei_zone, cp);
637 linklen = MAXPATHLEN - auio.uio_resid;
639 if (ndp->ni_pathlen > 1)
640 uma_zfree(namei_zone, cp);
644 if (linklen + ndp->ni_pathlen > MAXPATHLEN) {
645 if (ndp->ni_pathlen > 1)
646 uma_zfree(namei_zone, cp);
647 error = ENAMETOOLONG;
650 if (ndp->ni_pathlen > 1) {
651 bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen);
652 uma_zfree(namei_zone, cnp->cn_pnbuf);
655 cnp->cn_pnbuf[linklen] = '\0';
656 ndp->ni_pathlen += linklen;
660 * Check if root directory should replace current directory.
662 cnp->cn_nameptr = cnp->cn_pnbuf;
663 if (*(cnp->cn_nameptr) == '/') {
665 error = namei_handle_root(ndp, &dp);
675 namei_cleanup_cnp(cnp);
676 nameicap_cleanup(ndp, true);
677 SDT_PROBE3(vfs, namei, lookup, return, error, NULL, false);
683 compute_cn_lkflags(struct mount *mp, int lkflags, int cnflags)
686 if (mp == NULL || ((lkflags & LK_SHARED) &&
687 (!(mp->mnt_kern_flag & MNTK_LOOKUP_SHARED) ||
688 ((cnflags & ISDOTDOT) &&
689 (mp->mnt_kern_flag & MNTK_LOOKUP_EXCL_DOTDOT))))) {
690 lkflags &= ~LK_SHARED;
691 lkflags |= LK_EXCLUSIVE;
693 lkflags |= LK_NODDLKTREAT;
698 needs_exclusive_leaf(struct mount *mp, int flags)
702 * Intermediate nodes can use shared locks, we only need to
703 * force an exclusive lock for leaf nodes.
705 if ((flags & (ISLASTCN | LOCKLEAF)) != (ISLASTCN | LOCKLEAF))
708 /* Always use exclusive locks if LOCKSHARED isn't set. */
709 if (!(flags & LOCKSHARED))
713 * For lookups during open(), if the mount point supports
714 * extended shared operations, then use a shared lock for the
715 * leaf node, otherwise use an exclusive lock.
717 if ((flags & ISOPEN) != 0)
718 return (!MNT_EXTENDED_SHARED(mp));
721 * Lookup requests outside of open() that specify LOCKSHARED
722 * only need a shared lock on the leaf vnode.
729 * This is a very central and rather complicated routine.
731 * The pathname is pointed to by ni_ptr and is of length ni_pathlen.
732 * The starting directory is taken from ni_startdir. The pathname is
733 * descended until done, or a symbolic link is encountered. The variable
734 * ni_more is clear if the path is completed; it is set to one if a
735 * symbolic link needing interpretation is encountered.
737 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on
738 * whether the name is to be looked up, created, renamed, or deleted.
739 * When CREATE, RENAME, or DELETE is specified, information usable in
740 * creating, renaming, or deleting a directory entry may be calculated.
741 * If flag has LOCKPARENT or'ed into it, the parent directory is returned
742 * locked. If flag has WANTPARENT or'ed into it, the parent directory is
743 * returned unlocked. Otherwise the parent directory is not returned. If
744 * the target of the pathname exists and LOCKLEAF is or'ed into the flag
745 * the target is returned locked, otherwise it is returned unlocked.
746 * When creating or renaming and LOCKPARENT is specified, the target may not
747 * be ".". When deleting and LOCKPARENT is specified, the target may be ".".
749 * Overall outline of lookup:
752 * identify next component of name at ndp->ni_ptr
753 * handle degenerate case where name is null string
754 * if .. and crossing mount points and on mounted filesys, find parent
755 * call VOP_LOOKUP routine for next component name
756 * directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set
757 * component vnode returned in ni_vp (if it exists), locked.
758 * if result vnode is mounted on and crossing mount points,
759 * find mounted on vnode
760 * if more components of name, do next level at dirloop
761 * return the answer in ni_vp, locked if LOCKLEAF set
762 * if LOCKPARENT set, return locked parent in ni_dvp
763 * if WANTPARENT set, return unlocked parent in ni_dvp
766 lookup(struct nameidata *ndp)
768 char *cp; /* pointer into pathname argument */
769 char *prev_ni_next; /* saved ndp->ni_next */
770 struct vnode *dp = NULL; /* the directory we are searching */
771 struct vnode *tdp; /* saved dp */
772 struct mount *mp; /* mount table entry */
774 size_t prev_ni_pathlen; /* saved ndp->ni_pathlen */
775 int docache; /* == 0 do not cache last component */
776 int wantparent; /* 1 => wantparent or lockparent flag */
777 int rdonly; /* lookup read-only flag bit */
779 int dpunlocked = 0; /* dp has already been unlocked */
780 int relookup = 0; /* do not consume the path component */
781 struct componentname *cnp = &ndp->ni_cnd;
786 * Setup: break out flag bits into variables.
789 wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT);
790 KASSERT(cnp->cn_nameiop == LOOKUP || wantparent,
791 ("CREATE, DELETE, RENAME require LOCKPARENT or WANTPARENT."));
793 * When set to zero, docache causes the last component of the
794 * pathname to be deleted from the cache and the full lookup
795 * of the name to be done (via VOP_CACHEDLOOKUP()). Often
796 * filesystems need some pre-computed values that are made
797 * during the full lookup, for instance UFS sets dp->i_offset.
799 * The docache variable is set to zero when requested by the
800 * NOCACHE flag and for all modifying operations except CREATE.
802 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE;
803 if (cnp->cn_nameiop == DELETE ||
804 (wantparent && cnp->cn_nameiop != CREATE &&
805 cnp->cn_nameiop != LOOKUP))
807 rdonly = cnp->cn_flags & RDONLY;
808 cnp->cn_flags &= ~ISSYMLINK;
811 * We use shared locks until we hit the parent of the last cn then
812 * we adjust based on the requesting flags.
814 cnp->cn_lkflags = LK_SHARED;
815 dp = ndp->ni_startdir;
816 ndp->ni_startdir = NULLVP;
818 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | LK_RETRY,
823 * Search a new directory.
825 * The last component of the filename is left accessible via
826 * cnp->cn_nameptr for callers that need the name. Callers needing
827 * the name set the SAVENAME flag. When done, they assume
828 * responsibility for freeing the pathname buffer.
830 for (cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++)
832 cnp->cn_namelen = cp - cnp->cn_nameptr;
833 if (cnp->cn_namelen > NAME_MAX) {
834 error = ENAMETOOLONG;
837 #ifdef NAMEI_DIAGNOSTIC
840 printf("{%s}: ", cnp->cn_nameptr);
843 prev_ni_pathlen = ndp->ni_pathlen;
844 ndp->ni_pathlen -= cnp->cn_namelen;
845 KASSERT(ndp->ni_pathlen <= PATH_MAX,
846 ("%s: ni_pathlen underflow to %zd\n", __func__, ndp->ni_pathlen));
847 prev_ni_next = ndp->ni_next;
851 * Replace multiple slashes by a single slash and trailing slashes
852 * by a null. This must be done before VOP_LOOKUP() because some
853 * fs's don't know about trailing slashes. Remember if there were
854 * trailing slashes to handle symlinks, existing non-directories
855 * and non-existing files that won't be directories specially later.
857 while (*cp == '/' && (cp[1] == '/' || cp[1] == '\0')) {
861 *ndp->ni_next = '\0';
862 cnp->cn_flags |= TRAILINGSLASH;
867 cnp->cn_flags |= MAKEENTRY;
868 if (*cp == '\0' && docache == 0)
869 cnp->cn_flags &= ~MAKEENTRY;
870 if (cnp->cn_namelen == 2 &&
871 cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.')
872 cnp->cn_flags |= ISDOTDOT;
874 cnp->cn_flags &= ~ISDOTDOT;
875 if (*ndp->ni_next == 0)
876 cnp->cn_flags |= ISLASTCN;
878 cnp->cn_flags &= ~ISLASTCN;
880 if ((cnp->cn_flags & ISLASTCN) != 0 &&
881 cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.' &&
882 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
887 nameicap_tracker_add(ndp, dp);
890 * Check for degenerate name (e.g. / or "")
891 * which is a way of talking about a directory,
892 * e.g. like "/." or ".".
894 if (cnp->cn_nameptr[0] == '\0') {
895 if (dp->v_type != VDIR) {
899 if (cnp->cn_nameiop != LOOKUP) {
909 if (cnp->cn_flags & AUDITVNODE1)
910 AUDIT_ARG_VNODE1(dp);
911 else if (cnp->cn_flags & AUDITVNODE2)
912 AUDIT_ARG_VNODE2(dp);
914 if (!(cnp->cn_flags & (LOCKPARENT | LOCKLEAF)))
916 /* XXX This should probably move to the top of function. */
917 if (cnp->cn_flags & SAVESTART)
918 panic("lookup: SAVESTART");
923 * Handle "..": five special cases.
924 * 0. If doing a capability lookup and lookup_cap_dotdot is
925 * disabled, return ENOTCAPABLE.
926 * 1. Return an error if this is the last component of
927 * the name and the operation is DELETE or RENAME.
928 * 2. If at root directory (e.g. after chroot)
929 * or at absolute root directory
930 * then ignore it so can't get out.
931 * 3. If this vnode is the root of a mounted
932 * filesystem, then replace it with the
933 * vnode which was mounted on so we take the
934 * .. in the other filesystem.
935 * 4. If the vnode is the top directory of
936 * the jail or chroot, don't let them out.
937 * 5. If doing a capability lookup and lookup_cap_dotdot is
938 * enabled, return ENOTCAPABLE if the lookup would escape
939 * from the initial file descriptor directory. Checks are
940 * done by ensuring that namei() already traversed the
941 * result of dotdot lookup.
943 if (cnp->cn_flags & ISDOTDOT) {
944 if ((ndp->ni_lcf & (NI_LCF_STRICTRELATIVE | NI_LCF_CAP_DOTDOT))
945 == NI_LCF_STRICTRELATIVE) {
947 if (KTRPOINT(curthread, KTR_CAPFAIL))
948 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
953 if ((cnp->cn_flags & ISLASTCN) != 0 &&
954 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
959 for (pr = cnp->cn_cred->cr_prison; pr != NULL;
961 if (dp == pr->pr_root)
963 if (dp == ndp->ni_rootdir ||
964 dp == ndp->ni_topdir ||
967 ((dp->v_vflag & VV_ROOT) != 0 &&
968 (cnp->cn_flags & NOCROSSMOUNT) != 0)) {
974 if ((dp->v_vflag & VV_ROOT) == 0)
976 if (VN_IS_DOOMED(dp)) { /* forced unmount */
981 dp = dp->v_mount->mnt_vnodecovered;
985 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags |
986 LK_RETRY, ISDOTDOT));
987 error = nameicap_check_dotdot(ndp, dp);
990 if (KTRPOINT(curthread, KTR_CAPFAIL))
991 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
999 * We now have a segment name to search for, and a directory to search.
1003 error = mac_vnode_check_lookup(cnp->cn_thread->td_ucred, dp, cnp);
1009 ASSERT_VOP_LOCKED(dp, "lookup");
1011 * If we have a shared lock we may need to upgrade the lock for the
1014 if ((cnp->cn_flags & LOCKPARENT) && (cnp->cn_flags & ISLASTCN) &&
1015 dp != vp_crossmp && VOP_ISLOCKED(dp) == LK_SHARED)
1016 vn_lock(dp, LK_UPGRADE|LK_RETRY);
1017 if (VN_IS_DOOMED(dp)) {
1022 * If we're looking up the last component and we need an exclusive
1023 * lock, adjust our lkflags.
1025 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags))
1026 cnp->cn_lkflags = LK_EXCLUSIVE;
1027 #ifdef NAMEI_DIAGNOSTIC
1028 vn_printf(dp, "lookup in ");
1030 lkflags_save = cnp->cn_lkflags;
1031 cnp->cn_lkflags = compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags,
1033 error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp);
1034 cnp->cn_lkflags = lkflags_save;
1036 KASSERT(ndp->ni_vp == NULL, ("leaf should be empty"));
1037 #ifdef NAMEI_DIAGNOSTIC
1038 printf("not found\n");
1040 if ((error == ENOENT) &&
1041 (dp->v_vflag & VV_ROOT) && (dp->v_mount != NULL) &&
1042 (dp->v_mount->mnt_flag & MNT_UNION)) {
1044 dp = dp->v_mount->mnt_vnodecovered;
1048 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags |
1049 LK_RETRY, cnp->cn_flags));
1050 nameicap_tracker_add(ndp, dp);
1054 if (error == ERELOOKUP) {
1062 if (error != EJUSTRETURN)
1065 * At this point, we know we're at the end of the
1066 * pathname. If creating / renaming, we can consider
1067 * allowing the file or directory to be created / renamed,
1068 * provided we're not on a read-only filesystem.
1074 /* trailing slash only allowed for directories */
1075 if ((cnp->cn_flags & TRAILINGSLASH) &&
1076 !(cnp->cn_flags & WILLBEDIR)) {
1080 if ((cnp->cn_flags & LOCKPARENT) == 0)
1083 * We return with ni_vp NULL to indicate that the entry
1084 * doesn't currently exist, leaving a pointer to the
1085 * (possibly locked) directory vnode in ndp->ni_dvp.
1087 if (cnp->cn_flags & SAVESTART) {
1088 ndp->ni_startdir = ndp->ni_dvp;
1089 VREF(ndp->ni_startdir);
1095 #ifdef NAMEI_DIAGNOSTIC
1101 * Check to see if the vnode has been mounted on;
1102 * if so find the root of the mounted filesystem.
1104 while (dp->v_type == VDIR && (mp = dp->v_mountedhere) &&
1105 (cnp->cn_flags & NOCROSSMOUNT) == 0) {
1106 if (vfs_busy(mp, 0))
1109 if (dp != ndp->ni_dvp)
1113 vrefact(vp_crossmp);
1114 ndp->ni_dvp = vp_crossmp;
1115 error = VFS_ROOT(mp, compute_cn_lkflags(mp, cnp->cn_lkflags,
1116 cnp->cn_flags), &tdp);
1118 if (vn_lock(vp_crossmp, LK_SHARED | LK_NOWAIT))
1119 panic("vp_crossmp exclusively locked or reclaimed");
1124 ndp->ni_vp = dp = tdp;
1128 * Check for symbolic link
1130 if ((dp->v_type == VLNK) &&
1131 ((cnp->cn_flags & FOLLOW) || (cnp->cn_flags & TRAILINGSLASH) ||
1132 *ndp->ni_next == '/')) {
1133 cnp->cn_flags |= ISSYMLINK;
1134 if (VN_IS_DOOMED(dp)) {
1136 * We can't know whether the directory was mounted with
1137 * NOSYMFOLLOW, so we can't follow safely.
1142 if (dp->v_mount->mnt_flag & MNT_NOSYMFOLLOW) {
1147 * Symlink code always expects an unlocked dvp.
1149 if (ndp->ni_dvp != ndp->ni_vp) {
1150 VOP_UNLOCK(ndp->ni_dvp);
1151 ni_dvp_unlocked = 1;
1158 * Not a symbolic link that we will follow. Continue with the
1159 * next component if there is any; otherwise, we're done.
1161 KASSERT((cnp->cn_flags & ISLASTCN) || *ndp->ni_next == '/',
1162 ("lookup: invalid path state."));
1165 ndp->ni_pathlen = prev_ni_pathlen;
1166 ndp->ni_next = prev_ni_next;
1167 if (ndp->ni_dvp != dp)
1173 if (cnp->cn_flags & ISDOTDOT) {
1174 error = nameicap_check_dotdot(ndp, ndp->ni_vp);
1177 if (KTRPOINT(curthread, KTR_CAPFAIL))
1178 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
1183 if (*ndp->ni_next == '/') {
1184 cnp->cn_nameptr = ndp->ni_next;
1185 while (*cnp->cn_nameptr == '/') {
1189 if (ndp->ni_dvp != dp)
1196 * If we're processing a path with a trailing slash,
1197 * check that the end result is a directory.
1199 if ((cnp->cn_flags & TRAILINGSLASH) && dp->v_type != VDIR) {
1204 * Disallow directory write attempts on read-only filesystems.
1207 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
1211 if (cnp->cn_flags & SAVESTART) {
1212 ndp->ni_startdir = ndp->ni_dvp;
1213 VREF(ndp->ni_startdir);
1216 ni_dvp_unlocked = 2;
1217 if (ndp->ni_dvp != dp)
1221 } else if ((cnp->cn_flags & LOCKPARENT) == 0 && ndp->ni_dvp != dp) {
1222 VOP_UNLOCK(ndp->ni_dvp);
1223 ni_dvp_unlocked = 1;
1226 if (cnp->cn_flags & AUDITVNODE1)
1227 AUDIT_ARG_VNODE1(dp);
1228 else if (cnp->cn_flags & AUDITVNODE2)
1229 AUDIT_ARG_VNODE2(dp);
1231 if ((cnp->cn_flags & LOCKLEAF) == 0)
1235 * FIXME: for lookups which only cross a mount point to fetch the
1236 * root vnode, ni_dvp will be set to vp_crossmp. This can be a problem
1237 * if either WANTPARENT or LOCKPARENT is set.
1240 * Because of shared lookup we may have the vnode shared locked, but
1241 * the caller may want it to be exclusively locked.
1243 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags) &&
1244 VOP_ISLOCKED(dp) != LK_EXCLUSIVE) {
1245 vn_lock(dp, LK_UPGRADE | LK_RETRY);
1246 if (VN_IS_DOOMED(dp)) {
1254 if (ni_dvp_unlocked != 2) {
1255 if (dp != ndp->ni_dvp && !ni_dvp_unlocked)
1268 * relookup - lookup a path name component
1269 * Used by lookup to re-acquire things.
1272 relookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp)
1274 struct vnode *dp = NULL; /* the directory we are searching */
1275 int wantparent; /* 1 => wantparent or lockparent flag */
1276 int rdonly; /* lookup read-only flag bit */
1279 KASSERT(cnp->cn_flags & ISLASTCN,
1280 ("relookup: Not given last component."));
1282 * Setup: break out flag bits into variables.
1284 wantparent = cnp->cn_flags & (LOCKPARENT|WANTPARENT);
1285 KASSERT(wantparent, ("relookup: parent not wanted."));
1286 rdonly = cnp->cn_flags & RDONLY;
1287 cnp->cn_flags &= ~ISSYMLINK;
1289 cnp->cn_lkflags = LK_EXCLUSIVE;
1290 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY);
1293 * Search a new directory.
1295 * The last component of the filename is left accessible via
1296 * cnp->cn_nameptr for callers that need the name. Callers needing
1297 * the name set the SAVENAME flag. When done, they assume
1298 * responsibility for freeing the pathname buffer.
1300 #ifdef NAMEI_DIAGNOSTIC
1301 printf("{%s}: ", cnp->cn_nameptr);
1305 * Check for "" which represents the root directory after slash
1308 if (cnp->cn_nameptr[0] == '\0') {
1310 * Support only LOOKUP for "/" because lookup()
1311 * can't succeed for CREATE, DELETE and RENAME.
1313 KASSERT(cnp->cn_nameiop == LOOKUP, ("nameiop must be LOOKUP"));
1314 KASSERT(dp->v_type == VDIR, ("dp is not a directory"));
1316 if (!(cnp->cn_flags & LOCKLEAF))
1319 /* XXX This should probably move to the top of function. */
1320 if (cnp->cn_flags & SAVESTART)
1321 panic("lookup: SAVESTART");
1325 if (cnp->cn_flags & ISDOTDOT)
1326 panic ("relookup: lookup on dot-dot");
1329 * We now have a segment name to search for, and a directory to search.
1331 #ifdef NAMEI_DIAGNOSTIC
1332 vn_printf(dp, "search in ");
1334 if ((error = VOP_LOOKUP(dp, vpp, cnp)) != 0) {
1335 KASSERT(*vpp == NULL, ("leaf should be empty"));
1336 if (error != EJUSTRETURN)
1339 * If creating and at end of pathname, then can consider
1340 * allowing file to be created.
1346 /* ASSERT(dvp == ndp->ni_startdir) */
1347 if (cnp->cn_flags & SAVESTART)
1349 if ((cnp->cn_flags & LOCKPARENT) == 0)
1352 * We return with ni_vp NULL to indicate that the entry
1353 * doesn't currently exist, leaving a pointer to the
1354 * (possibly locked) directory vnode in ndp->ni_dvp.
1362 * Disallow directory write attempts on read-only filesystems.
1365 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
1374 * Set the parent lock/ref state to the requested state.
1376 if ((cnp->cn_flags & LOCKPARENT) == 0 && dvp != dp) {
1381 } else if (!wantparent)
1384 * Check for symbolic link
1386 KASSERT(dp->v_type != VLNK || !(cnp->cn_flags & FOLLOW),
1387 ("relookup: symlink found.\n"));
1389 /* ASSERT(dvp == ndp->ni_startdir) */
1390 if (cnp->cn_flags & SAVESTART)
1393 if ((cnp->cn_flags & LOCKLEAF) == 0)
1403 * Free data allocated by namei(); see namei(9) for details.
1406 NDFREE_PNBUF(struct nameidata *ndp)
1409 if ((ndp->ni_cnd.cn_flags & HASBUF) != 0) {
1410 MPASS((ndp->ni_cnd.cn_flags & (SAVENAME | SAVESTART)) != 0);
1411 uma_zfree(namei_zone, ndp->ni_cnd.cn_pnbuf);
1412 ndp->ni_cnd.cn_flags &= ~HASBUF;
1417 (NDFREE)(struct nameidata *ndp, const u_int flags)
1425 if (!(flags & NDF_NO_FREE_PNBUF)) {
1428 if (!(flags & NDF_NO_VP_UNLOCK) &&
1429 (ndp->ni_cnd.cn_flags & LOCKLEAF) && ndp->ni_vp)
1431 if (!(flags & NDF_NO_DVP_UNLOCK) &&
1432 (ndp->ni_cnd.cn_flags & LOCKPARENT) &&
1433 ndp->ni_dvp != ndp->ni_vp)
1435 if (!(flags & NDF_NO_VP_RELE) && ndp->ni_vp) {
1444 VOP_UNLOCK(ndp->ni_vp);
1445 if (!(flags & NDF_NO_DVP_RELE) &&
1446 (ndp->ni_cnd.cn_flags & (LOCKPARENT|WANTPARENT))) {
1455 VOP_UNLOCK(ndp->ni_dvp);
1456 if (!(flags & NDF_NO_STARTDIR_RELE) &&
1457 (ndp->ni_cnd.cn_flags & SAVESTART)) {
1458 vrele(ndp->ni_startdir);
1459 ndp->ni_startdir = NULL;
1465 * Validate the final state of ndp after the lookup.
1467 * Historically filesystems were allowed to modify cn_flags. Most notably they
1468 * can add SAVENAME to the request, resulting in HASBUF and pushing subsequent
1469 * clean up to the consumer. In practice this seems to only concern != LOOKUP
1472 * As a step towards stricter API contract this routine validates the state to
1473 * clean up. Note validation is a work in progress with the intent of becoming
1474 * stricter over time.
1476 #define NDMODIFYINGFLAGS (LOCKLEAF | LOCKPARENT | WANTPARENT | SAVENAME | SAVESTART | HASBUF)
1478 NDVALIDATE(struct nameidata *ndp)
1480 struct componentname *cnp;
1481 u_int64_t used, orig;
1484 orig = cnp->cn_origflags;
1485 used = cnp->cn_flags;
1486 switch (cnp->cn_nameiop) {
1489 * For plain lookup we require strict conformance -- nothing
1490 * to clean up if it was not requested by the caller.
1492 orig &= NDMODIFYINGFLAGS;
1493 used &= NDMODIFYINGFLAGS;
1494 if ((orig & (SAVENAME | SAVESTART)) != 0)
1504 * Some filesystems set SAVENAME to provoke HASBUF, accomodate
1505 * for it until it gets fixed.
1507 orig &= NDMODIFYINGFLAGS;
1508 orig |= (SAVENAME | HASBUF);
1509 used &= NDMODIFYINGFLAGS;
1510 used |= (SAVENAME | HASBUF);
1518 panic("%s: mismatched flags for op %d: added %" PRIx64 ", "
1519 "removed %" PRIx64" (%" PRIx64" != %" PRIx64"; stored %" PRIx64" != %" PRIx64")",
1520 __func__, cnp->cn_nameiop, used & ~orig, orig &~ used,
1521 orig, used, cnp->cn_origflags, cnp->cn_flags);
1526 * Determine if there is a suitable alternate filename under the specified
1527 * prefix for the specified path. If the create flag is set, then the
1528 * alternate prefix will be used so long as the parent directory exists.
1529 * This is used by the various compatibility ABIs so that Linux binaries prefer
1530 * files under /compat/linux for example. The chosen path (whether under
1531 * the prefix or under /) is returned in a kernel malloc'd buffer pointed
1532 * to by pathbuf. The caller is responsible for free'ing the buffer from
1533 * the M_TEMP bucket if one is returned.
1536 kern_alternate_path(struct thread *td, const char *prefix, const char *path,
1537 enum uio_seg pathseg, char **pathbuf, int create, int dirfd)
1539 struct nameidata nd, ndroot;
1540 char *ptr, *buf, *cp;
1544 buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
1547 /* Copy the prefix into the new pathname as a starting point. */
1548 len = strlcpy(buf, prefix, MAXPATHLEN);
1549 if (len >= MAXPATHLEN) {
1554 sz = MAXPATHLEN - len;
1557 /* Append the filename to the prefix. */
1558 if (pathseg == UIO_SYSSPACE)
1559 error = copystr(path, ptr, sz, &len);
1561 error = copyinstr(path, ptr, sz, &len);
1569 /* Only use a prefix with absolute pathnames. */
1575 if (dirfd != AT_FDCWD) {
1577 * We want the original because the "prefix" is
1578 * included in the already opened dirfd.
1580 bcopy(ptr, buf, len);
1585 * We know that there is a / somewhere in this pathname.
1586 * Search backwards for it, to find the file's parent dir
1587 * to see if it exists in the alternate tree. If it does,
1588 * and we want to create a file (cflag is set). We don't
1589 * need to worry about the root comparison in this case.
1593 for (cp = &ptr[len] - 1; *cp != '/'; cp--);
1596 NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_SYSSPACE, buf, td);
1602 NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_SYSSPACE, buf, td);
1609 * We now compare the vnode of the prefix to the one
1610 * vnode asked. If they resolve to be the same, then we
1611 * ignore the match so that the real root gets used.
1612 * This avoids the problem of traversing "../.." to find the
1613 * root directory and never finding it, because "/" resolves
1614 * to the emulation root directory. This is expensive :-(
1616 NDINIT(&ndroot, LOOKUP, FOLLOW, UIO_SYSSPACE, prefix,
1619 /* We shouldn't ever get an error from this namei(). */
1620 error = namei(&ndroot);
1622 if (nd.ni_vp == ndroot.ni_vp)
1625 NDFREE(&ndroot, NDF_ONLY_PNBUF);
1626 vrele(ndroot.ni_vp);
1630 NDFREE(&nd, NDF_ONLY_PNBUF);
1634 /* If there was an error, use the original path name. */
1636 bcopy(ptr, buf, len);