2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1982, 1986, 1989, 1993
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6 * (c) UNIX System Laboratories, Inc.
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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 ndp->ni_resflags |= NIRES_STRICTREL;
326 if (ndp->ni_dirfd == AT_FDCWD) {
328 if (KTRPOINT(td, KTR_CAPFAIL))
329 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
338 * Get starting point for the translation.
342 * The reference on ni_rootdir is acquired in the block below to avoid
343 * back-to-back atomics for absolute lookups.
345 ndp->ni_rootdir = pwd->pwd_rdir;
346 ndp->ni_topdir = pwd->pwd_jdir;
348 if (cnp->cn_pnbuf[0] == '/') {
349 ndp->ni_resflags |= NIRES_ABS;
350 error = namei_handle_root(ndp, dpp);
352 if (ndp->ni_startdir != NULL) {
353 *dpp = ndp->ni_startdir;
354 startdir_used = true;
355 } else if (ndp->ni_dirfd == AT_FDCWD) {
356 *dpp = pwd->pwd_cdir;
359 rights = *ndp->ni_rightsneeded;
360 cap_rights_set_one(&rights, CAP_LOOKUP);
362 if (cnp->cn_flags & AUDITVNODE1)
363 AUDIT_ARG_ATFD1(ndp->ni_dirfd);
364 if (cnp->cn_flags & AUDITVNODE2)
365 AUDIT_ARG_ATFD2(ndp->ni_dirfd);
367 * Effectively inlined fgetvp_rights, because we need to
368 * inspect the file as well as grabbing the vnode.
370 error = fget_cap(td, ndp->ni_dirfd, &rights,
371 &dfp, &ndp->ni_filecaps);
374 * Preserve the error; it should either be EBADF
375 * or capability-related, both of which can be
376 * safely returned to the caller.
379 if (dfp->f_ops == &badfileops) {
381 } else if (dfp->f_vnode == NULL) {
387 if ((dfp->f_flag & FSEARCH) != 0)
388 cnp->cn_flags |= NOEXECCHECK;
394 * If file descriptor doesn't have all rights,
395 * all lookups relative to it must also be
399 if (!cap_rights_contains(&ndp->ni_filecaps.fc_rights,
401 ndp->ni_filecaps.fc_fcntls != CAP_FCNTL_ALL ||
402 ndp->ni_filecaps.fc_nioctls != -1) {
403 ndp->ni_lcf |= NI_LCF_STRICTRELATIVE;
404 ndp->ni_resflags |= NIRES_STRICTREL;
408 if (error == 0 && (*dpp)->v_type != VDIR)
411 if (error == 0 && (cnp->cn_flags & BENEATH) != 0) {
412 if (ndp->ni_dirfd == AT_FDCWD) {
413 ndp->ni_beneath_latch = pwd->pwd_cdir;
414 vrefact(ndp->ni_beneath_latch);
416 rights = *ndp->ni_rightsneeded;
417 cap_rights_set_one(&rights, CAP_LOOKUP);
418 error = fgetvp_rights(td, ndp->ni_dirfd, &rights,
419 &dirfd_caps, &ndp->ni_beneath_latch);
420 if (error == 0 && (*dpp)->v_type != VDIR) {
421 vrele(ndp->ni_beneath_latch);
426 ndp->ni_lcf |= NI_LCF_LATCH;
429 * If we are auditing the kernel pathname, save the user pathname.
431 if (cnp->cn_flags & AUDITVNODE1)
432 AUDIT_ARG_UPATH1_VP(td, ndp->ni_rootdir, *dpp, cnp->cn_pnbuf);
433 if (cnp->cn_flags & AUDITVNODE2)
434 AUDIT_ARG_UPATH2_VP(td, ndp->ni_rootdir, *dpp, cnp->cn_pnbuf);
435 if (ndp->ni_startdir != NULL && !startdir_used)
436 vrele(ndp->ni_startdir);
443 MPASS((ndp->ni_lcf & (NI_LCF_BENEATH_ABS | NI_LCF_LATCH)) !=
445 if (((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) != 0 &&
446 lookup_cap_dotdot != 0) ||
447 ((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) == 0 &&
448 (cnp->cn_flags & BENEATH) != 0))
449 ndp->ni_lcf |= NI_LCF_CAP_DOTDOT;
450 SDT_PROBE4(vfs, namei, lookup, entry, *dpp, cnp->cn_pnbuf,
451 cnp->cn_flags, false);
457 * Convert a pathname into a pointer to a locked vnode.
459 * The FOLLOW flag is set when symbolic links are to be followed
460 * when they occur at the end of the name translation process.
461 * Symbolic links are always followed for all other pathname
462 * components other than the last.
464 * The segflg defines whether the name is to be copied from user
465 * space or kernel space.
467 * Overall outline of namei:
470 * get starting directory
471 * while (!done && !error) {
472 * call lookup to search path.
473 * if symbolic link, massage name in buffer and continue
477 namei(struct nameidata *ndp)
479 char *cp; /* pointer into pathname argument */
480 struct vnode *dp; /* the directory we are searching */
481 struct iovec aiov; /* uio for reading symbolic links */
482 struct componentname *cnp;
487 enum cache_fpl_status status;
495 * While NDINIT may seem like a more natural place to do it, there are
496 * callers which directly modify flags past invoking init.
498 cnp->cn_origflags = cnp->cn_flags;
500 ndp->ni_cnd.cn_cred = ndp->ni_cnd.cn_thread->td_ucred;
501 KASSERT(cnp->cn_cred && td->td_proc, ("namei: bad cred/proc"));
502 KASSERT((cnp->cn_flags & NAMEI_INTERNAL_FLAGS) == 0,
503 ("namei: unexpected flags: %" PRIx64 "\n",
504 cnp->cn_flags & NAMEI_INTERNAL_FLAGS));
505 if (cnp->cn_flags & NOCACHE)
506 KASSERT(cnp->cn_nameiop != LOOKUP,
507 ("%s: NOCACHE passed with LOOKUP", __func__));
508 MPASS(ndp->ni_startdir == NULL || ndp->ni_startdir->v_type == VDIR ||
509 ndp->ni_startdir->v_type == VBAD);
515 * Get a buffer for the name to be translated, and copy the
516 * name into the buffer.
518 cnp->cn_pnbuf = uma_zalloc(namei_zone, M_WAITOK);
519 if (ndp->ni_segflg == UIO_SYSSPACE)
520 error = copystr(ndp->ni_dirp, cnp->cn_pnbuf, MAXPATHLEN,
523 error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf, MAXPATHLEN,
526 if (__predict_false(error != 0)) {
527 namei_cleanup_cnp(cnp);
532 * Don't allow empty pathnames.
534 if (__predict_false(*cnp->cn_pnbuf == '\0')) {
535 namei_cleanup_cnp(cnp);
540 if (KTRPOINT(td, KTR_NAMEI)) {
541 KASSERT(cnp->cn_thread == curthread,
542 ("namei not using curthread"));
543 ktrnamei(cnp->cn_pnbuf);
547 cnp->cn_nameptr = cnp->cn_pnbuf;
550 * First try looking up the target without locking any vnodes.
552 * We may need to start from scratch or pick up where it left off.
554 error = cache_fplookup(ndp, &status, &pwd);
556 case CACHE_FPL_STATUS_UNSET:
557 __assert_unreachable();
559 case CACHE_FPL_STATUS_HANDLED:
563 case CACHE_FPL_STATUS_PARTIAL:
564 TAILQ_INIT(&ndp->ni_cap_tracker);
565 dp = ndp->ni_startdir;
567 case CACHE_FPL_STATUS_ABORTED:
568 TAILQ_INIT(&ndp->ni_cap_tracker);
569 error = namei_setup(ndp, &dp, &pwd);
571 namei_cleanup_cnp(cnp);
583 ndp->ni_startdir = dp;
588 * If not a symbolic link, we're done.
590 if ((cnp->cn_flags & ISSYMLINK) == 0) {
591 if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) {
592 namei_cleanup_cnp(cnp);
594 cnp->cn_flags |= HASBUF;
595 if ((ndp->ni_lcf & (NI_LCF_BENEATH_ABS |
596 NI_LCF_BENEATH_LATCHED)) == NI_LCF_BENEATH_ABS) {
600 nameicap_cleanup(ndp, true);
601 SDT_PROBE3(vfs, namei, lookup, return, error,
602 (error == 0 ? ndp->ni_vp : NULL), false);
608 if (ndp->ni_loopcnt++ >= MAXSYMLINKS) {
613 if ((cnp->cn_flags & NOMACCHECK) == 0) {
614 error = mac_vnode_check_readlink(td->td_ucred,
620 if (ndp->ni_pathlen > 1)
621 cp = uma_zalloc(namei_zone, M_WAITOK);
625 aiov.iov_len = MAXPATHLEN;
626 auio.uio_iov = &aiov;
629 auio.uio_rw = UIO_READ;
630 auio.uio_segflg = UIO_SYSSPACE;
632 auio.uio_resid = MAXPATHLEN;
633 error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred);
635 if (ndp->ni_pathlen > 1)
636 uma_zfree(namei_zone, cp);
639 linklen = MAXPATHLEN - auio.uio_resid;
641 if (ndp->ni_pathlen > 1)
642 uma_zfree(namei_zone, cp);
646 if (linklen + ndp->ni_pathlen > MAXPATHLEN) {
647 if (ndp->ni_pathlen > 1)
648 uma_zfree(namei_zone, cp);
649 error = ENAMETOOLONG;
652 if (ndp->ni_pathlen > 1) {
653 bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen);
654 uma_zfree(namei_zone, cnp->cn_pnbuf);
657 cnp->cn_pnbuf[linklen] = '\0';
658 ndp->ni_pathlen += linklen;
662 * Check if root directory should replace current directory.
664 cnp->cn_nameptr = cnp->cn_pnbuf;
665 if (*(cnp->cn_nameptr) == '/') {
667 error = namei_handle_root(ndp, &dp);
677 namei_cleanup_cnp(cnp);
678 nameicap_cleanup(ndp, true);
679 SDT_PROBE3(vfs, namei, lookup, return, error, NULL, false);
685 compute_cn_lkflags(struct mount *mp, int lkflags, int cnflags)
688 if (mp == NULL || ((lkflags & LK_SHARED) &&
689 (!(mp->mnt_kern_flag & MNTK_LOOKUP_SHARED) ||
690 ((cnflags & ISDOTDOT) &&
691 (mp->mnt_kern_flag & MNTK_LOOKUP_EXCL_DOTDOT))))) {
692 lkflags &= ~LK_SHARED;
693 lkflags |= LK_EXCLUSIVE;
695 lkflags |= LK_NODDLKTREAT;
700 needs_exclusive_leaf(struct mount *mp, int flags)
704 * Intermediate nodes can use shared locks, we only need to
705 * force an exclusive lock for leaf nodes.
707 if ((flags & (ISLASTCN | LOCKLEAF)) != (ISLASTCN | LOCKLEAF))
710 /* Always use exclusive locks if LOCKSHARED isn't set. */
711 if (!(flags & LOCKSHARED))
715 * For lookups during open(), if the mount point supports
716 * extended shared operations, then use a shared lock for the
717 * leaf node, otherwise use an exclusive lock.
719 if ((flags & ISOPEN) != 0)
720 return (!MNT_EXTENDED_SHARED(mp));
723 * Lookup requests outside of open() that specify LOCKSHARED
724 * only need a shared lock on the leaf vnode.
731 * This is a very central and rather complicated routine.
733 * The pathname is pointed to by ni_ptr and is of length ni_pathlen.
734 * The starting directory is taken from ni_startdir. The pathname is
735 * descended until done, or a symbolic link is encountered. The variable
736 * ni_more is clear if the path is completed; it is set to one if a
737 * symbolic link needing interpretation is encountered.
739 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on
740 * whether the name is to be looked up, created, renamed, or deleted.
741 * When CREATE, RENAME, or DELETE is specified, information usable in
742 * creating, renaming, or deleting a directory entry may be calculated.
743 * If flag has LOCKPARENT or'ed into it, the parent directory is returned
744 * locked. If flag has WANTPARENT or'ed into it, the parent directory is
745 * returned unlocked. Otherwise the parent directory is not returned. If
746 * the target of the pathname exists and LOCKLEAF is or'ed into the flag
747 * the target is returned locked, otherwise it is returned unlocked.
748 * When creating or renaming and LOCKPARENT is specified, the target may not
749 * be ".". When deleting and LOCKPARENT is specified, the target may be ".".
751 * Overall outline of lookup:
754 * identify next component of name at ndp->ni_ptr
755 * handle degenerate case where name is null string
756 * if .. and crossing mount points and on mounted filesys, find parent
757 * call VOP_LOOKUP routine for next component name
758 * directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set
759 * component vnode returned in ni_vp (if it exists), locked.
760 * if result vnode is mounted on and crossing mount points,
761 * find mounted on vnode
762 * if more components of name, do next level at dirloop
763 * return the answer in ni_vp, locked if LOCKLEAF set
764 * if LOCKPARENT set, return locked parent in ni_dvp
765 * if WANTPARENT set, return unlocked parent in ni_dvp
768 lookup(struct nameidata *ndp)
770 char *cp; /* pointer into pathname argument */
771 char *prev_ni_next; /* saved ndp->ni_next */
772 struct vnode *dp = NULL; /* the directory we are searching */
773 struct vnode *tdp; /* saved dp */
774 struct mount *mp; /* mount table entry */
776 size_t prev_ni_pathlen; /* saved ndp->ni_pathlen */
777 int docache; /* == 0 do not cache last component */
778 int wantparent; /* 1 => wantparent or lockparent flag */
779 int rdonly; /* lookup read-only flag bit */
781 int dpunlocked = 0; /* dp has already been unlocked */
782 int relookup = 0; /* do not consume the path component */
783 struct componentname *cnp = &ndp->ni_cnd;
788 * Setup: break out flag bits into variables.
791 wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT);
792 KASSERT(cnp->cn_nameiop == LOOKUP || wantparent,
793 ("CREATE, DELETE, RENAME require LOCKPARENT or WANTPARENT."));
795 * When set to zero, docache causes the last component of the
796 * pathname to be deleted from the cache and the full lookup
797 * of the name to be done (via VOP_CACHEDLOOKUP()). Often
798 * filesystems need some pre-computed values that are made
799 * during the full lookup, for instance UFS sets dp->i_offset.
801 * The docache variable is set to zero when requested by the
802 * NOCACHE flag and for all modifying operations except CREATE.
804 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE;
805 if (cnp->cn_nameiop == DELETE ||
806 (wantparent && cnp->cn_nameiop != CREATE &&
807 cnp->cn_nameiop != LOOKUP))
809 rdonly = cnp->cn_flags & RDONLY;
810 cnp->cn_flags &= ~ISSYMLINK;
813 * We use shared locks until we hit the parent of the last cn then
814 * we adjust based on the requesting flags.
816 cnp->cn_lkflags = LK_SHARED;
817 dp = ndp->ni_startdir;
818 ndp->ni_startdir = NULLVP;
820 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | LK_RETRY,
825 * Search a new directory.
827 * The last component of the filename is left accessible via
828 * cnp->cn_nameptr for callers that need the name. Callers needing
829 * the name set the SAVENAME flag. When done, they assume
830 * responsibility for freeing the pathname buffer.
832 for (cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++)
834 cnp->cn_namelen = cp - cnp->cn_nameptr;
835 if (cnp->cn_namelen > NAME_MAX) {
836 error = ENAMETOOLONG;
839 #ifdef NAMEI_DIAGNOSTIC
842 printf("{%s}: ", cnp->cn_nameptr);
845 prev_ni_pathlen = ndp->ni_pathlen;
846 ndp->ni_pathlen -= cnp->cn_namelen;
847 KASSERT(ndp->ni_pathlen <= PATH_MAX,
848 ("%s: ni_pathlen underflow to %zd\n", __func__, ndp->ni_pathlen));
849 prev_ni_next = ndp->ni_next;
853 * Replace multiple slashes by a single slash and trailing slashes
854 * by a null. This must be done before VOP_LOOKUP() because some
855 * fs's don't know about trailing slashes. Remember if there were
856 * trailing slashes to handle symlinks, existing non-directories
857 * and non-existing files that won't be directories specially later.
859 while (*cp == '/' && (cp[1] == '/' || cp[1] == '\0')) {
863 *ndp->ni_next = '\0';
864 cnp->cn_flags |= TRAILINGSLASH;
869 cnp->cn_flags |= MAKEENTRY;
870 if (*cp == '\0' && docache == 0)
871 cnp->cn_flags &= ~MAKEENTRY;
872 if (cnp->cn_namelen == 2 &&
873 cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.')
874 cnp->cn_flags |= ISDOTDOT;
876 cnp->cn_flags &= ~ISDOTDOT;
877 if (*ndp->ni_next == 0)
878 cnp->cn_flags |= ISLASTCN;
880 cnp->cn_flags &= ~ISLASTCN;
882 if ((cnp->cn_flags & ISLASTCN) != 0 &&
883 cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.' &&
884 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
889 nameicap_tracker_add(ndp, dp);
892 * Check for degenerate name (e.g. / or "")
893 * which is a way of talking about a directory,
894 * e.g. like "/." or ".".
896 if (cnp->cn_nameptr[0] == '\0') {
897 if (dp->v_type != VDIR) {
901 if (cnp->cn_nameiop != LOOKUP) {
911 if (cnp->cn_flags & AUDITVNODE1)
912 AUDIT_ARG_VNODE1(dp);
913 else if (cnp->cn_flags & AUDITVNODE2)
914 AUDIT_ARG_VNODE2(dp);
916 if (!(cnp->cn_flags & (LOCKPARENT | LOCKLEAF)))
918 /* XXX This should probably move to the top of function. */
919 if (cnp->cn_flags & SAVESTART)
920 panic("lookup: SAVESTART");
925 * Handle "..": five special cases.
926 * 0. If doing a capability lookup and lookup_cap_dotdot is
927 * disabled, return ENOTCAPABLE.
928 * 1. Return an error if this is the last component of
929 * the name and the operation is DELETE or RENAME.
930 * 2. If at root directory (e.g. after chroot)
931 * or at absolute root directory
932 * then ignore it so can't get out.
933 * 3. If this vnode is the root of a mounted
934 * filesystem, then replace it with the
935 * vnode which was mounted on so we take the
936 * .. in the other filesystem.
937 * 4. If the vnode is the top directory of
938 * the jail or chroot, don't let them out.
939 * 5. If doing a capability lookup and lookup_cap_dotdot is
940 * enabled, return ENOTCAPABLE if the lookup would escape
941 * from the initial file descriptor directory. Checks are
942 * done by ensuring that namei() already traversed the
943 * result of dotdot lookup.
945 if (cnp->cn_flags & ISDOTDOT) {
946 if ((ndp->ni_lcf & (NI_LCF_STRICTRELATIVE | NI_LCF_CAP_DOTDOT))
947 == NI_LCF_STRICTRELATIVE) {
949 if (KTRPOINT(curthread, KTR_CAPFAIL))
950 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
955 if ((cnp->cn_flags & ISLASTCN) != 0 &&
956 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
961 for (pr = cnp->cn_cred->cr_prison; pr != NULL;
963 if (dp == pr->pr_root)
965 if (dp == ndp->ni_rootdir ||
966 dp == ndp->ni_topdir ||
969 ((dp->v_vflag & VV_ROOT) != 0 &&
970 (cnp->cn_flags & NOCROSSMOUNT) != 0)) {
976 if ((dp->v_vflag & VV_ROOT) == 0)
978 if (VN_IS_DOOMED(dp)) { /* forced unmount */
983 dp = dp->v_mount->mnt_vnodecovered;
987 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags |
988 LK_RETRY, ISDOTDOT));
989 error = nameicap_check_dotdot(ndp, dp);
992 if (KTRPOINT(curthread, KTR_CAPFAIL))
993 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
1001 * We now have a segment name to search for, and a directory to search.
1005 error = mac_vnode_check_lookup(cnp->cn_thread->td_ucred, dp, cnp);
1011 ASSERT_VOP_LOCKED(dp, "lookup");
1013 * If we have a shared lock we may need to upgrade the lock for the
1016 if ((cnp->cn_flags & LOCKPARENT) && (cnp->cn_flags & ISLASTCN) &&
1017 dp != vp_crossmp && VOP_ISLOCKED(dp) == LK_SHARED)
1018 vn_lock(dp, LK_UPGRADE|LK_RETRY);
1019 if (VN_IS_DOOMED(dp)) {
1024 * If we're looking up the last component and we need an exclusive
1025 * lock, adjust our lkflags.
1027 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags))
1028 cnp->cn_lkflags = LK_EXCLUSIVE;
1029 #ifdef NAMEI_DIAGNOSTIC
1030 vn_printf(dp, "lookup in ");
1032 lkflags_save = cnp->cn_lkflags;
1033 cnp->cn_lkflags = compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags,
1035 error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp);
1036 cnp->cn_lkflags = lkflags_save;
1038 KASSERT(ndp->ni_vp == NULL, ("leaf should be empty"));
1039 #ifdef NAMEI_DIAGNOSTIC
1040 printf("not found\n");
1042 if ((error == ENOENT) &&
1043 (dp->v_vflag & VV_ROOT) && (dp->v_mount != NULL) &&
1044 (dp->v_mount->mnt_flag & MNT_UNION)) {
1046 dp = dp->v_mount->mnt_vnodecovered;
1050 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags |
1051 LK_RETRY, cnp->cn_flags));
1052 nameicap_tracker_add(ndp, dp);
1056 if (error == ERELOOKUP) {
1064 if (error != EJUSTRETURN)
1067 * At this point, we know we're at the end of the
1068 * pathname. If creating / renaming, we can consider
1069 * allowing the file or directory to be created / renamed,
1070 * provided we're not on a read-only filesystem.
1076 /* trailing slash only allowed for directories */
1077 if ((cnp->cn_flags & TRAILINGSLASH) &&
1078 !(cnp->cn_flags & WILLBEDIR)) {
1082 if ((cnp->cn_flags & LOCKPARENT) == 0)
1085 * We return with ni_vp NULL to indicate that the entry
1086 * doesn't currently exist, leaving a pointer to the
1087 * (possibly locked) directory vnode in ndp->ni_dvp.
1089 if (cnp->cn_flags & SAVESTART) {
1090 ndp->ni_startdir = ndp->ni_dvp;
1091 VREF(ndp->ni_startdir);
1097 #ifdef NAMEI_DIAGNOSTIC
1103 * Check to see if the vnode has been mounted on;
1104 * if so find the root of the mounted filesystem.
1106 while (dp->v_type == VDIR && (mp = dp->v_mountedhere) &&
1107 (cnp->cn_flags & NOCROSSMOUNT) == 0) {
1108 if (vfs_busy(mp, 0))
1111 if (dp != ndp->ni_dvp)
1115 vrefact(vp_crossmp);
1116 ndp->ni_dvp = vp_crossmp;
1117 error = VFS_ROOT(mp, compute_cn_lkflags(mp, cnp->cn_lkflags,
1118 cnp->cn_flags), &tdp);
1120 if (vn_lock(vp_crossmp, LK_SHARED | LK_NOWAIT))
1121 panic("vp_crossmp exclusively locked or reclaimed");
1126 ndp->ni_vp = dp = tdp;
1130 * Check for symbolic link
1132 if ((dp->v_type == VLNK) &&
1133 ((cnp->cn_flags & FOLLOW) || (cnp->cn_flags & TRAILINGSLASH) ||
1134 *ndp->ni_next == '/')) {
1135 cnp->cn_flags |= ISSYMLINK;
1136 if (VN_IS_DOOMED(dp)) {
1138 * We can't know whether the directory was mounted with
1139 * NOSYMFOLLOW, so we can't follow safely.
1144 if (dp->v_mount->mnt_flag & MNT_NOSYMFOLLOW) {
1149 * Symlink code always expects an unlocked dvp.
1151 if (ndp->ni_dvp != ndp->ni_vp) {
1152 VOP_UNLOCK(ndp->ni_dvp);
1153 ni_dvp_unlocked = 1;
1160 * Not a symbolic link that we will follow. Continue with the
1161 * next component if there is any; otherwise, we're done.
1163 KASSERT((cnp->cn_flags & ISLASTCN) || *ndp->ni_next == '/',
1164 ("lookup: invalid path state."));
1167 ndp->ni_pathlen = prev_ni_pathlen;
1168 ndp->ni_next = prev_ni_next;
1169 if (ndp->ni_dvp != dp)
1175 if (cnp->cn_flags & ISDOTDOT) {
1176 error = nameicap_check_dotdot(ndp, ndp->ni_vp);
1179 if (KTRPOINT(curthread, KTR_CAPFAIL))
1180 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
1185 if (*ndp->ni_next == '/') {
1186 cnp->cn_nameptr = ndp->ni_next;
1187 while (*cnp->cn_nameptr == '/') {
1191 if (ndp->ni_dvp != dp)
1198 * If we're processing a path with a trailing slash,
1199 * check that the end result is a directory.
1201 if ((cnp->cn_flags & TRAILINGSLASH) && dp->v_type != VDIR) {
1206 * Disallow directory write attempts on read-only filesystems.
1209 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
1213 if (cnp->cn_flags & SAVESTART) {
1214 ndp->ni_startdir = ndp->ni_dvp;
1215 VREF(ndp->ni_startdir);
1218 ni_dvp_unlocked = 2;
1219 if (ndp->ni_dvp != dp)
1223 } else if ((cnp->cn_flags & LOCKPARENT) == 0 && ndp->ni_dvp != dp) {
1224 VOP_UNLOCK(ndp->ni_dvp);
1225 ni_dvp_unlocked = 1;
1228 if (cnp->cn_flags & AUDITVNODE1)
1229 AUDIT_ARG_VNODE1(dp);
1230 else if (cnp->cn_flags & AUDITVNODE2)
1231 AUDIT_ARG_VNODE2(dp);
1233 if ((cnp->cn_flags & LOCKLEAF) == 0)
1237 * FIXME: for lookups which only cross a mount point to fetch the
1238 * root vnode, ni_dvp will be set to vp_crossmp. This can be a problem
1239 * if either WANTPARENT or LOCKPARENT is set.
1242 * Because of shared lookup we may have the vnode shared locked, but
1243 * the caller may want it to be exclusively locked.
1245 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags) &&
1246 VOP_ISLOCKED(dp) != LK_EXCLUSIVE) {
1247 vn_lock(dp, LK_UPGRADE | LK_RETRY);
1248 if (VN_IS_DOOMED(dp)) {
1253 if (ndp->ni_vp != NULL && ndp->ni_vp->v_type == VDIR)
1254 nameicap_tracker_add(ndp, ndp->ni_vp);
1258 if (ni_dvp_unlocked != 2) {
1259 if (dp != ndp->ni_dvp && !ni_dvp_unlocked)
1272 * relookup - lookup a path name component
1273 * Used by lookup to re-acquire things.
1276 relookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp)
1278 struct vnode *dp = NULL; /* the directory we are searching */
1279 int wantparent; /* 1 => wantparent or lockparent flag */
1280 int rdonly; /* lookup read-only flag bit */
1283 KASSERT(cnp->cn_flags & ISLASTCN,
1284 ("relookup: Not given last component."));
1286 * Setup: break out flag bits into variables.
1288 wantparent = cnp->cn_flags & (LOCKPARENT|WANTPARENT);
1289 KASSERT(wantparent, ("relookup: parent not wanted."));
1290 rdonly = cnp->cn_flags & RDONLY;
1291 cnp->cn_flags &= ~ISSYMLINK;
1293 cnp->cn_lkflags = LK_EXCLUSIVE;
1294 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY);
1297 * Search a new directory.
1299 * The last component of the filename is left accessible via
1300 * cnp->cn_nameptr for callers that need the name. Callers needing
1301 * the name set the SAVENAME flag. When done, they assume
1302 * responsibility for freeing the pathname buffer.
1304 #ifdef NAMEI_DIAGNOSTIC
1305 printf("{%s}: ", cnp->cn_nameptr);
1309 * Check for "" which represents the root directory after slash
1312 if (cnp->cn_nameptr[0] == '\0') {
1314 * Support only LOOKUP for "/" because lookup()
1315 * can't succeed for CREATE, DELETE and RENAME.
1317 KASSERT(cnp->cn_nameiop == LOOKUP, ("nameiop must be LOOKUP"));
1318 KASSERT(dp->v_type == VDIR, ("dp is not a directory"));
1320 if (!(cnp->cn_flags & LOCKLEAF))
1323 /* XXX This should probably move to the top of function. */
1324 if (cnp->cn_flags & SAVESTART)
1325 panic("lookup: SAVESTART");
1329 if (cnp->cn_flags & ISDOTDOT)
1330 panic ("relookup: lookup on dot-dot");
1333 * We now have a segment name to search for, and a directory to search.
1335 #ifdef NAMEI_DIAGNOSTIC
1336 vn_printf(dp, "search in ");
1338 if ((error = VOP_LOOKUP(dp, vpp, cnp)) != 0) {
1339 KASSERT(*vpp == NULL, ("leaf should be empty"));
1340 if (error != EJUSTRETURN)
1343 * If creating and at end of pathname, then can consider
1344 * allowing file to be created.
1350 /* ASSERT(dvp == ndp->ni_startdir) */
1351 if (cnp->cn_flags & SAVESTART)
1353 if ((cnp->cn_flags & LOCKPARENT) == 0)
1356 * We return with ni_vp NULL to indicate that the entry
1357 * doesn't currently exist, leaving a pointer to the
1358 * (possibly locked) directory vnode in ndp->ni_dvp.
1366 * Disallow directory write attempts on read-only filesystems.
1369 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
1378 * Set the parent lock/ref state to the requested state.
1380 if ((cnp->cn_flags & LOCKPARENT) == 0 && dvp != dp) {
1385 } else if (!wantparent)
1388 * Check for symbolic link
1390 KASSERT(dp->v_type != VLNK || !(cnp->cn_flags & FOLLOW),
1391 ("relookup: symlink found.\n"));
1393 /* ASSERT(dvp == ndp->ni_startdir) */
1394 if (cnp->cn_flags & SAVESTART)
1397 if ((cnp->cn_flags & LOCKLEAF) == 0)
1407 * Free data allocated by namei(); see namei(9) for details.
1410 NDFREE_PNBUF(struct nameidata *ndp)
1413 if ((ndp->ni_cnd.cn_flags & HASBUF) != 0) {
1414 MPASS((ndp->ni_cnd.cn_flags & (SAVENAME | SAVESTART)) != 0);
1415 uma_zfree(namei_zone, ndp->ni_cnd.cn_pnbuf);
1416 ndp->ni_cnd.cn_flags &= ~HASBUF;
1421 (NDFREE)(struct nameidata *ndp, const u_int flags)
1429 if (!(flags & NDF_NO_FREE_PNBUF)) {
1432 if (!(flags & NDF_NO_VP_UNLOCK) &&
1433 (ndp->ni_cnd.cn_flags & LOCKLEAF) && ndp->ni_vp)
1435 if (!(flags & NDF_NO_DVP_UNLOCK) &&
1436 (ndp->ni_cnd.cn_flags & LOCKPARENT) &&
1437 ndp->ni_dvp != ndp->ni_vp)
1439 if (!(flags & NDF_NO_VP_RELE) && ndp->ni_vp) {
1448 VOP_UNLOCK(ndp->ni_vp);
1449 if (!(flags & NDF_NO_DVP_RELE) &&
1450 (ndp->ni_cnd.cn_flags & (LOCKPARENT|WANTPARENT))) {
1459 VOP_UNLOCK(ndp->ni_dvp);
1460 if (!(flags & NDF_NO_STARTDIR_RELE) &&
1461 (ndp->ni_cnd.cn_flags & SAVESTART)) {
1462 vrele(ndp->ni_startdir);
1463 ndp->ni_startdir = NULL;
1469 * Validate the final state of ndp after the lookup.
1471 * Historically filesystems were allowed to modify cn_flags. Most notably they
1472 * can add SAVENAME to the request, resulting in HASBUF and pushing subsequent
1473 * clean up to the consumer. In practice this seems to only concern != LOOKUP
1476 * As a step towards stricter API contract this routine validates the state to
1477 * clean up. Note validation is a work in progress with the intent of becoming
1478 * stricter over time.
1480 #define NDMODIFYINGFLAGS (LOCKLEAF | LOCKPARENT | WANTPARENT | SAVENAME | SAVESTART | HASBUF)
1482 NDVALIDATE(struct nameidata *ndp)
1484 struct componentname *cnp;
1485 u_int64_t used, orig;
1488 orig = cnp->cn_origflags;
1489 used = cnp->cn_flags;
1490 switch (cnp->cn_nameiop) {
1493 * For plain lookup we require strict conformance -- nothing
1494 * to clean up if it was not requested by the caller.
1496 orig &= NDMODIFYINGFLAGS;
1497 used &= NDMODIFYINGFLAGS;
1498 if ((orig & (SAVENAME | SAVESTART)) != 0)
1508 * Some filesystems set SAVENAME to provoke HASBUF, accomodate
1509 * for it until it gets fixed.
1511 orig &= NDMODIFYINGFLAGS;
1512 orig |= (SAVENAME | HASBUF);
1513 used &= NDMODIFYINGFLAGS;
1514 used |= (SAVENAME | HASBUF);
1522 panic("%s: mismatched flags for op %d: added %" PRIx64 ", "
1523 "removed %" PRIx64" (%" PRIx64" != %" PRIx64"; stored %" PRIx64" != %" PRIx64")",
1524 __func__, cnp->cn_nameiop, used & ~orig, orig &~ used,
1525 orig, used, cnp->cn_origflags, cnp->cn_flags);
1530 * Determine if there is a suitable alternate filename under the specified
1531 * prefix for the specified path. If the create flag is set, then the
1532 * alternate prefix will be used so long as the parent directory exists.
1533 * This is used by the various compatibility ABIs so that Linux binaries prefer
1534 * files under /compat/linux for example. The chosen path (whether under
1535 * the prefix or under /) is returned in a kernel malloc'd buffer pointed
1536 * to by pathbuf. The caller is responsible for free'ing the buffer from
1537 * the M_TEMP bucket if one is returned.
1540 kern_alternate_path(struct thread *td, const char *prefix, const char *path,
1541 enum uio_seg pathseg, char **pathbuf, int create, int dirfd)
1543 struct nameidata nd, ndroot;
1544 char *ptr, *buf, *cp;
1548 buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
1551 /* Copy the prefix into the new pathname as a starting point. */
1552 len = strlcpy(buf, prefix, MAXPATHLEN);
1553 if (len >= MAXPATHLEN) {
1558 sz = MAXPATHLEN - len;
1561 /* Append the filename to the prefix. */
1562 if (pathseg == UIO_SYSSPACE)
1563 error = copystr(path, ptr, sz, &len);
1565 error = copyinstr(path, ptr, sz, &len);
1573 /* Only use a prefix with absolute pathnames. */
1579 if (dirfd != AT_FDCWD) {
1581 * We want the original because the "prefix" is
1582 * included in the already opened dirfd.
1584 bcopy(ptr, buf, len);
1589 * We know that there is a / somewhere in this pathname.
1590 * Search backwards for it, to find the file's parent dir
1591 * to see if it exists in the alternate tree. If it does,
1592 * and we want to create a file (cflag is set). We don't
1593 * need to worry about the root comparison in this case.
1597 for (cp = &ptr[len] - 1; *cp != '/'; cp--);
1600 NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_SYSSPACE, buf, td);
1606 NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_SYSSPACE, buf, td);
1613 * We now compare the vnode of the prefix to the one
1614 * vnode asked. If they resolve to be the same, then we
1615 * ignore the match so that the real root gets used.
1616 * This avoids the problem of traversing "../.." to find the
1617 * root directory and never finding it, because "/" resolves
1618 * to the emulation root directory. This is expensive :-(
1620 NDINIT(&ndroot, LOOKUP, FOLLOW, UIO_SYSSPACE, prefix,
1623 /* We shouldn't ever get an error from this namei(). */
1624 error = namei(&ndroot);
1626 if (nd.ni_vp == ndroot.ni_vp)
1629 NDFREE(&ndroot, NDF_ONLY_PNBUF);
1630 vrele(ndroot.ni_vp);
1634 NDFREE(&nd, NDF_ONLY_PNBUF);
1638 /* If there was an error, use the original path name. */
1640 bcopy(ptr, buf, len);