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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9 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
10 * the permission of UNIX System Laboratories, Inc.
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13 * modification, are permitted provided that the following conditions
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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 <security/audit/audit.h>
66 #include <security/mac/mac_framework.h>
70 #define NAMEI_DIAGNOSTIC 1
71 #undef NAMEI_DIAGNOSTIC
73 SDT_PROVIDER_DECLARE(vfs);
74 SDT_PROBE_DEFINE4(vfs, namei, lookup, entry, "struct vnode *", "char *",
75 "unsigned long", "bool");
76 SDT_PROBE_DEFINE3(vfs, namei, lookup, return, "int", "struct vnode *", "bool");
78 /* Allocation zone for namei. */
79 uma_zone_t namei_zone;
81 /* Placeholder vnode for mp traversal. */
82 static struct vnode *vp_crossmp;
85 crossmp_vop_islocked(struct vop_islocked_args *ap)
92 crossmp_vop_lock1(struct vop_lock1_args *ap)
95 struct lock *lk __unused;
96 const char *file __unused;
97 int flags, line __unused;
105 if ((flags & LK_SHARED) == 0)
106 panic("invalid lock request for crossmp");
108 WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER, file, line,
109 flags & LK_INTERLOCK ? &VI_MTX(vp)->lock_object : NULL);
110 WITNESS_LOCK(&lk->lock_object, 0, file, line);
111 if ((flags & LK_INTERLOCK) != 0)
113 LOCK_LOG_LOCK("SLOCK", &lk->lock_object, 0, 0, ap->a_file, line);
118 crossmp_vop_unlock(struct vop_unlock_args *ap)
121 struct lock *lk __unused;
126 WITNESS_UNLOCK(&lk->lock_object, 0, LOCK_FILE, LOCK_LINE);
127 LOCK_LOG_LOCK("SUNLOCK", &lk->lock_object, 0, 0, LOCK_FILE,
132 static struct vop_vector crossmp_vnodeops = {
133 .vop_default = &default_vnodeops,
134 .vop_islocked = crossmp_vop_islocked,
135 .vop_lock1 = crossmp_vop_lock1,
136 .vop_unlock = crossmp_vop_unlock,
139 * VFS_VOP_VECTOR_REGISTER(crossmp_vnodeops) is not used here since the vnode
140 * gets allocated early. See nameiinit for the direct call below.
143 struct nameicap_tracker {
145 TAILQ_ENTRY(nameicap_tracker) nm_link;
148 /* Zone for cap mode tracker elements used for dotdot capability checks. */
149 static uma_zone_t nt_zone;
152 nameiinit(void *dummy __unused)
155 namei_zone = uma_zcreate("NAMEI", MAXPATHLEN, NULL, NULL, NULL, NULL,
157 nt_zone = uma_zcreate("rentr", sizeof(struct nameicap_tracker),
158 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
159 vfs_vector_op_register(&crossmp_vnodeops);
160 getnewvnode("crossmp", NULL, &crossmp_vnodeops, &vp_crossmp);
162 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nameiinit, NULL);
164 static int lookup_cap_dotdot = 1;
165 SYSCTL_INT(_vfs, OID_AUTO, lookup_cap_dotdot, CTLFLAG_RWTUN,
166 &lookup_cap_dotdot, 0,
167 "enables \"..\" components in path lookup in capability mode");
168 static int lookup_cap_dotdot_nonlocal = 1;
169 SYSCTL_INT(_vfs, OID_AUTO, lookup_cap_dotdot_nonlocal, CTLFLAG_RWTUN,
170 &lookup_cap_dotdot_nonlocal, 0,
171 "enables \"..\" components in path lookup in capability mode "
172 "on non-local mount");
175 nameicap_tracker_add(struct nameidata *ndp, struct vnode *dp)
177 struct nameicap_tracker *nt;
179 if ((ndp->ni_lcf & NI_LCF_CAP_DOTDOT) == 0 || dp->v_type != VDIR)
181 if ((ndp->ni_lcf & (NI_LCF_BENEATH_ABS | NI_LCF_BENEATH_LATCHED)) ==
182 NI_LCF_BENEATH_ABS) {
183 MPASS((ndp->ni_lcf & NI_LCF_LATCH) != 0);
184 if (dp != ndp->ni_beneath_latch)
186 ndp->ni_lcf |= NI_LCF_BENEATH_LATCHED;
188 nt = uma_zalloc(nt_zone, M_WAITOK);
191 TAILQ_INSERT_TAIL(&ndp->ni_cap_tracker, nt, nm_link);
195 nameicap_cleanup(struct nameidata *ndp, bool clean_latch)
197 struct nameicap_tracker *nt, *nt1;
199 KASSERT(TAILQ_EMPTY(&ndp->ni_cap_tracker) ||
200 (ndp->ni_lcf & NI_LCF_CAP_DOTDOT) != 0, ("not strictrelative"));
201 TAILQ_FOREACH_SAFE(nt, &ndp->ni_cap_tracker, nm_link, nt1) {
202 TAILQ_REMOVE(&ndp->ni_cap_tracker, nt, nm_link);
204 uma_zfree(nt_zone, nt);
206 if (clean_latch && (ndp->ni_lcf & NI_LCF_LATCH) != 0) {
207 ndp->ni_lcf &= ~NI_LCF_LATCH;
208 vrele(ndp->ni_beneath_latch);
213 * For dotdot lookups in capability mode, only allow the component
214 * lookup to succeed if the resulting directory was already traversed
215 * during the operation. Also fail dotdot lookups for non-local
216 * filesystems, where external agents might assist local lookups to
217 * escape the compartment.
220 nameicap_check_dotdot(struct nameidata *ndp, struct vnode *dp)
222 struct nameicap_tracker *nt;
225 if ((ndp->ni_lcf & NI_LCF_CAP_DOTDOT) == 0 || dp == NULL ||
229 if (lookup_cap_dotdot_nonlocal == 0 && mp != NULL &&
230 (mp->mnt_flag & MNT_LOCAL) == 0)
231 return (ENOTCAPABLE);
232 TAILQ_FOREACH_REVERSE(nt, &ndp->ni_cap_tracker, nameicap_tracker_head,
237 if ((ndp->ni_lcf & NI_LCF_BENEATH_ABS) != 0) {
238 ndp->ni_lcf &= ~NI_LCF_BENEATH_LATCHED;
239 nameicap_cleanup(ndp, false);
242 return (ENOTCAPABLE);
246 namei_cleanup_cnp(struct componentname *cnp)
249 uma_zfree(namei_zone, cnp->cn_pnbuf);
251 cnp->cn_pnbuf = NULL;
252 cnp->cn_nameptr = NULL;
257 namei_handle_root(struct nameidata *ndp, struct vnode **dpp)
259 struct componentname *cnp;
262 if ((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) != 0) {
264 if (KTRPOINT(curthread, KTR_CAPFAIL))
265 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
267 return (ENOTCAPABLE);
269 if ((cnp->cn_flags & BENEATH) != 0) {
270 ndp->ni_lcf |= NI_LCF_BENEATH_ABS;
271 ndp->ni_lcf &= ~NI_LCF_BENEATH_LATCHED;
272 nameicap_cleanup(ndp, false);
274 while (*(cnp->cn_nameptr) == '/') {
278 *dpp = ndp->ni_rootdir;
284 namei_setup(struct nameidata *ndp, struct vnode **dpp, struct pwd **pwdp)
286 struct componentname *cnp;
291 struct filecaps dirfd_caps;
298 startdir_used = false;
302 #ifdef CAPABILITY_MODE
304 * In capability mode, lookups must be restricted to happen in
305 * the subtree with the root specified by the file descriptor:
306 * - The root must be real file descriptor, not the pseudo-descriptor
308 * - The passed path must be relative and not absolute.
309 * - If lookup_cap_dotdot is disabled, path must not contain the
311 * - If lookup_cap_dotdot is enabled, we verify that all '..'
312 * components lookups result in the directories which were
313 * previously walked by us, which prevents an escape from
316 if (IN_CAPABILITY_MODE(td) && (cnp->cn_flags & NOCAPCHECK) == 0) {
317 ndp->ni_lcf |= NI_LCF_STRICTRELATIVE;
318 if (ndp->ni_dirfd == AT_FDCWD) {
320 if (KTRPOINT(td, KTR_CAPFAIL))
321 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
330 * Get starting point for the translation.
334 * The reference on ni_rootdir is acquired in the block below to avoid
335 * back-to-back atomics for absolute lookups.
337 ndp->ni_rootdir = pwd->pwd_rdir;
338 ndp->ni_topdir = pwd->pwd_jdir;
340 if (cnp->cn_pnbuf[0] == '/') {
341 ndp->ni_resflags |= NIRES_ABS;
342 error = namei_handle_root(ndp, dpp);
344 if (ndp->ni_startdir != NULL) {
345 *dpp = ndp->ni_startdir;
346 startdir_used = true;
347 } else if (ndp->ni_dirfd == AT_FDCWD) {
348 *dpp = pwd->pwd_cdir;
351 rights = *ndp->ni_rightsneeded;
352 cap_rights_set_one(&rights, CAP_LOOKUP);
354 if (cnp->cn_flags & AUDITVNODE1)
355 AUDIT_ARG_ATFD1(ndp->ni_dirfd);
356 if (cnp->cn_flags & AUDITVNODE2)
357 AUDIT_ARG_ATFD2(ndp->ni_dirfd);
359 * Effectively inlined fgetvp_rights, because we need to
360 * inspect the file as well as grabbing the vnode.
362 error = fget_cap(td, ndp->ni_dirfd, &rights,
363 &dfp, &ndp->ni_filecaps);
366 * Preserve the error; it should either be EBADF
367 * or capability-related, both of which can be
368 * safely returned to the caller.
371 if (dfp->f_ops == &badfileops) {
373 } else if (dfp->f_vnode == NULL) {
379 if ((dfp->f_flag & FSEARCH) != 0)
380 cnp->cn_flags |= NOEXECCHECK;
386 * If file descriptor doesn't have all rights,
387 * all lookups relative to it must also be
391 if (!cap_rights_contains(&ndp->ni_filecaps.fc_rights,
393 ndp->ni_filecaps.fc_fcntls != CAP_FCNTL_ALL ||
394 ndp->ni_filecaps.fc_nioctls != -1) {
395 ndp->ni_lcf |= NI_LCF_STRICTRELATIVE;
399 if (error == 0 && (*dpp)->v_type != VDIR)
402 if (error == 0 && (cnp->cn_flags & BENEATH) != 0) {
403 if (ndp->ni_dirfd == AT_FDCWD) {
404 ndp->ni_beneath_latch = pwd->pwd_cdir;
405 vrefact(ndp->ni_beneath_latch);
407 rights = *ndp->ni_rightsneeded;
408 cap_rights_set_one(&rights, CAP_LOOKUP);
409 error = fgetvp_rights(td, ndp->ni_dirfd, &rights,
410 &dirfd_caps, &ndp->ni_beneath_latch);
411 if (error == 0 && (*dpp)->v_type != VDIR) {
412 vrele(ndp->ni_beneath_latch);
417 ndp->ni_lcf |= NI_LCF_LATCH;
420 * If we are auditing the kernel pathname, save the user pathname.
422 if (cnp->cn_flags & AUDITVNODE1)
423 AUDIT_ARG_UPATH1_VP(td, ndp->ni_rootdir, *dpp, cnp->cn_pnbuf);
424 if (cnp->cn_flags & AUDITVNODE2)
425 AUDIT_ARG_UPATH2_VP(td, ndp->ni_rootdir, *dpp, cnp->cn_pnbuf);
426 if (ndp->ni_startdir != NULL && !startdir_used)
427 vrele(ndp->ni_startdir);
433 MPASS((ndp->ni_lcf & (NI_LCF_BENEATH_ABS | NI_LCF_LATCH)) !=
435 if (((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) != 0 &&
436 lookup_cap_dotdot != 0) ||
437 ((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) == 0 &&
438 (cnp->cn_flags & BENEATH) != 0))
439 ndp->ni_lcf |= NI_LCF_CAP_DOTDOT;
440 SDT_PROBE4(vfs, namei, lookup, entry, *dpp, cnp->cn_pnbuf,
441 cnp->cn_flags, false);
447 * Convert a pathname into a pointer to a locked vnode.
449 * The FOLLOW flag is set when symbolic links are to be followed
450 * when they occur at the end of the name translation process.
451 * Symbolic links are always followed for all other pathname
452 * components other than the last.
454 * The segflg defines whether the name is to be copied from user
455 * space or kernel space.
457 * Overall outline of namei:
460 * get starting directory
461 * while (!done && !error) {
462 * call lookup to search path.
463 * if symbolic link, massage name in buffer and continue
467 namei(struct nameidata *ndp)
469 char *cp; /* pointer into pathname argument */
470 struct vnode *dp; /* the directory we are searching */
471 struct iovec aiov; /* uio for reading symbolic links */
472 struct componentname *cnp;
477 enum cache_fpl_status status;
481 ndp->ni_cnd.cn_cred = ndp->ni_cnd.cn_thread->td_ucred;
482 KASSERT(cnp->cn_cred && td->td_proc, ("namei: bad cred/proc"));
483 KASSERT((cnp->cn_nameiop & (~OPMASK)) == 0,
484 ("namei: nameiop contaminated with flags"));
485 KASSERT((cnp->cn_flags & OPMASK) == 0,
486 ("namei: flags contaminated with nameiops"));
487 if (cnp->cn_flags & NOCACHE)
488 KASSERT(cnp->cn_nameiop != LOOKUP,
489 ("%s: NOCACHE passed with LOOKUP", __func__));
490 MPASS(ndp->ni_startdir == NULL || ndp->ni_startdir->v_type == VDIR ||
491 ndp->ni_startdir->v_type == VBAD);
493 /* We will set this ourselves if we need it. */
494 cnp->cn_flags &= ~TRAILINGSLASH;
500 * Get a buffer for the name to be translated, and copy the
501 * name into the buffer.
503 if ((cnp->cn_flags & HASBUF) == 0)
504 cnp->cn_pnbuf = uma_zalloc(namei_zone, M_WAITOK);
505 if (ndp->ni_segflg == UIO_SYSSPACE)
506 error = copystr(ndp->ni_dirp, cnp->cn_pnbuf, MAXPATHLEN,
509 error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf, MAXPATHLEN,
512 if (__predict_false(error != 0)) {
513 namei_cleanup_cnp(cnp);
518 * Don't allow empty pathnames.
520 if (__predict_false(*cnp->cn_pnbuf == '\0')) {
521 namei_cleanup_cnp(cnp);
526 if (KTRPOINT(td, KTR_NAMEI)) {
527 KASSERT(cnp->cn_thread == curthread,
528 ("namei not using curthread"));
529 ktrnamei(cnp->cn_pnbuf);
533 cnp->cn_nameptr = cnp->cn_pnbuf;
536 * First try looking up the target without locking any vnodes.
538 * We may need to start from scratch or pick up where it left off.
540 error = cache_fplookup(ndp, &status, &pwd);
542 case CACHE_FPL_STATUS_UNSET:
543 __assert_unreachable();
545 case CACHE_FPL_STATUS_HANDLED:
547 case CACHE_FPL_STATUS_PARTIAL:
548 TAILQ_INIT(&ndp->ni_cap_tracker);
549 dp = ndp->ni_startdir;
551 case CACHE_FPL_STATUS_ABORTED:
552 TAILQ_INIT(&ndp->ni_cap_tracker);
553 error = namei_setup(ndp, &dp, &pwd);
555 namei_cleanup_cnp(cnp);
567 ndp->ni_startdir = dp;
572 * If not a symbolic link, we're done.
574 if ((cnp->cn_flags & ISSYMLINK) == 0) {
575 if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) {
576 namei_cleanup_cnp(cnp);
578 cnp->cn_flags |= HASBUF;
579 if ((ndp->ni_lcf & (NI_LCF_BENEATH_ABS |
580 NI_LCF_BENEATH_LATCHED)) == NI_LCF_BENEATH_ABS) {
584 nameicap_cleanup(ndp, true);
585 SDT_PROBE3(vfs, namei, lookup, return, error,
586 (error == 0 ? ndp->ni_vp : NULL), false);
590 if (ndp->ni_loopcnt++ >= MAXSYMLINKS) {
595 if ((cnp->cn_flags & NOMACCHECK) == 0) {
596 error = mac_vnode_check_readlink(td->td_ucred,
602 if (ndp->ni_pathlen > 1)
603 cp = uma_zalloc(namei_zone, M_WAITOK);
607 aiov.iov_len = MAXPATHLEN;
608 auio.uio_iov = &aiov;
611 auio.uio_rw = UIO_READ;
612 auio.uio_segflg = UIO_SYSSPACE;
614 auio.uio_resid = MAXPATHLEN;
615 error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred);
617 if (ndp->ni_pathlen > 1)
618 uma_zfree(namei_zone, cp);
621 linklen = MAXPATHLEN - auio.uio_resid;
623 if (ndp->ni_pathlen > 1)
624 uma_zfree(namei_zone, cp);
628 if (linklen + ndp->ni_pathlen > MAXPATHLEN) {
629 if (ndp->ni_pathlen > 1)
630 uma_zfree(namei_zone, cp);
631 error = ENAMETOOLONG;
634 if (ndp->ni_pathlen > 1) {
635 bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen);
636 uma_zfree(namei_zone, cnp->cn_pnbuf);
639 cnp->cn_pnbuf[linklen] = '\0';
640 ndp->ni_pathlen += linklen;
644 * Check if root directory should replace current directory.
646 cnp->cn_nameptr = cnp->cn_pnbuf;
647 if (*(cnp->cn_nameptr) == '/') {
649 error = namei_handle_root(ndp, &dp);
659 namei_cleanup_cnp(cnp);
660 nameicap_cleanup(ndp, true);
661 SDT_PROBE3(vfs, namei, lookup, return, error, NULL, false);
667 compute_cn_lkflags(struct mount *mp, int lkflags, int cnflags)
670 if (mp == NULL || ((lkflags & LK_SHARED) &&
671 (!(mp->mnt_kern_flag & MNTK_LOOKUP_SHARED) ||
672 ((cnflags & ISDOTDOT) &&
673 (mp->mnt_kern_flag & MNTK_LOOKUP_EXCL_DOTDOT))))) {
674 lkflags &= ~LK_SHARED;
675 lkflags |= LK_EXCLUSIVE;
677 lkflags |= LK_NODDLKTREAT;
682 needs_exclusive_leaf(struct mount *mp, int flags)
686 * Intermediate nodes can use shared locks, we only need to
687 * force an exclusive lock for leaf nodes.
689 if ((flags & (ISLASTCN | LOCKLEAF)) != (ISLASTCN | LOCKLEAF))
692 /* Always use exclusive locks if LOCKSHARED isn't set. */
693 if (!(flags & LOCKSHARED))
697 * For lookups during open(), if the mount point supports
698 * extended shared operations, then use a shared lock for the
699 * leaf node, otherwise use an exclusive lock.
701 if ((flags & ISOPEN) != 0)
702 return (!MNT_EXTENDED_SHARED(mp));
705 * Lookup requests outside of open() that specify LOCKSHARED
706 * only need a shared lock on the leaf vnode.
713 * This is a very central and rather complicated routine.
715 * The pathname is pointed to by ni_ptr and is of length ni_pathlen.
716 * The starting directory is taken from ni_startdir. The pathname is
717 * descended until done, or a symbolic link is encountered. The variable
718 * ni_more is clear if the path is completed; it is set to one if a
719 * symbolic link needing interpretation is encountered.
721 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on
722 * whether the name is to be looked up, created, renamed, or deleted.
723 * When CREATE, RENAME, or DELETE is specified, information usable in
724 * creating, renaming, or deleting a directory entry may be calculated.
725 * If flag has LOCKPARENT or'ed into it, the parent directory is returned
726 * locked. If flag has WANTPARENT or'ed into it, the parent directory is
727 * returned unlocked. Otherwise the parent directory is not returned. If
728 * the target of the pathname exists and LOCKLEAF is or'ed into the flag
729 * the target is returned locked, otherwise it is returned unlocked.
730 * When creating or renaming and LOCKPARENT is specified, the target may not
731 * be ".". When deleting and LOCKPARENT is specified, the target may be ".".
733 * Overall outline of lookup:
736 * identify next component of name at ndp->ni_ptr
737 * handle degenerate case where name is null string
738 * if .. and crossing mount points and on mounted filesys, find parent
739 * call VOP_LOOKUP routine for next component name
740 * directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set
741 * component vnode returned in ni_vp (if it exists), locked.
742 * if result vnode is mounted on and crossing mount points,
743 * find mounted on vnode
744 * if more components of name, do next level at dirloop
745 * return the answer in ni_vp, locked if LOCKLEAF set
746 * if LOCKPARENT set, return locked parent in ni_dvp
747 * if WANTPARENT set, return unlocked parent in ni_dvp
750 lookup(struct nameidata *ndp)
752 char *cp; /* pointer into pathname argument */
753 char *prev_ni_next; /* saved ndp->ni_next */
754 struct vnode *dp = NULL; /* the directory we are searching */
755 struct vnode *tdp; /* saved dp */
756 struct mount *mp; /* mount table entry */
758 size_t prev_ni_pathlen; /* saved ndp->ni_pathlen */
759 int docache; /* == 0 do not cache last component */
760 int wantparent; /* 1 => wantparent or lockparent flag */
761 int rdonly; /* lookup read-only flag bit */
763 int dpunlocked = 0; /* dp has already been unlocked */
764 int relookup = 0; /* do not consume the path component */
765 struct componentname *cnp = &ndp->ni_cnd;
770 * Setup: break out flag bits into variables.
773 wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT);
774 KASSERT(cnp->cn_nameiop == LOOKUP || wantparent,
775 ("CREATE, DELETE, RENAME require LOCKPARENT or WANTPARENT."));
776 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE;
777 if (cnp->cn_nameiop == DELETE ||
778 (wantparent && cnp->cn_nameiop != CREATE &&
779 cnp->cn_nameiop != LOOKUP))
781 rdonly = cnp->cn_flags & RDONLY;
782 cnp->cn_flags &= ~ISSYMLINK;
785 * We use shared locks until we hit the parent of the last cn then
786 * we adjust based on the requesting flags.
788 cnp->cn_lkflags = LK_SHARED;
789 dp = ndp->ni_startdir;
790 ndp->ni_startdir = NULLVP;
792 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | LK_RETRY,
797 * Search a new directory.
799 * The last component of the filename is left accessible via
800 * cnp->cn_nameptr for callers that need the name. Callers needing
801 * the name set the SAVENAME flag. When done, they assume
802 * responsibility for freeing the pathname buffer.
804 for (cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++)
806 cnp->cn_namelen = cp - cnp->cn_nameptr;
807 if (cnp->cn_namelen > NAME_MAX) {
808 error = ENAMETOOLONG;
811 #ifdef NAMEI_DIAGNOSTIC
814 printf("{%s}: ", cnp->cn_nameptr);
817 prev_ni_pathlen = ndp->ni_pathlen;
818 ndp->ni_pathlen -= cnp->cn_namelen;
819 KASSERT(ndp->ni_pathlen <= PATH_MAX,
820 ("%s: ni_pathlen underflow to %zd\n", __func__, ndp->ni_pathlen));
821 prev_ni_next = ndp->ni_next;
825 * Replace multiple slashes by a single slash and trailing slashes
826 * by a null. This must be done before VOP_LOOKUP() because some
827 * fs's don't know about trailing slashes. Remember if there were
828 * trailing slashes to handle symlinks, existing non-directories
829 * and non-existing files that won't be directories specially later.
831 while (*cp == '/' && (cp[1] == '/' || cp[1] == '\0')) {
835 *ndp->ni_next = '\0';
836 cnp->cn_flags |= TRAILINGSLASH;
841 cnp->cn_flags |= MAKEENTRY;
842 if (*cp == '\0' && docache == 0)
843 cnp->cn_flags &= ~MAKEENTRY;
844 if (cnp->cn_namelen == 2 &&
845 cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.')
846 cnp->cn_flags |= ISDOTDOT;
848 cnp->cn_flags &= ~ISDOTDOT;
849 if (*ndp->ni_next == 0)
850 cnp->cn_flags |= ISLASTCN;
852 cnp->cn_flags &= ~ISLASTCN;
854 if ((cnp->cn_flags & ISLASTCN) != 0 &&
855 cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.' &&
856 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
861 nameicap_tracker_add(ndp, dp);
864 * Check for degenerate name (e.g. / or "")
865 * which is a way of talking about a directory,
866 * e.g. like "/." or ".".
868 if (cnp->cn_nameptr[0] == '\0') {
869 if (dp->v_type != VDIR) {
873 if (cnp->cn_nameiop != LOOKUP) {
883 if (cnp->cn_flags & AUDITVNODE1)
884 AUDIT_ARG_VNODE1(dp);
885 else if (cnp->cn_flags & AUDITVNODE2)
886 AUDIT_ARG_VNODE2(dp);
888 if (!(cnp->cn_flags & (LOCKPARENT | LOCKLEAF)))
890 /* XXX This should probably move to the top of function. */
891 if (cnp->cn_flags & SAVESTART)
892 panic("lookup: SAVESTART");
897 * Handle "..": five special cases.
898 * 0. If doing a capability lookup and lookup_cap_dotdot is
899 * disabled, return ENOTCAPABLE.
900 * 1. Return an error if this is the last component of
901 * the name and the operation is DELETE or RENAME.
902 * 2. If at root directory (e.g. after chroot)
903 * or at absolute root directory
904 * then ignore it so can't get out.
905 * 3. If this vnode is the root of a mounted
906 * filesystem, then replace it with the
907 * vnode which was mounted on so we take the
908 * .. in the other filesystem.
909 * 4. If the vnode is the top directory of
910 * the jail or chroot, don't let them out.
911 * 5. If doing a capability lookup and lookup_cap_dotdot is
912 * enabled, return ENOTCAPABLE if the lookup would escape
913 * from the initial file descriptor directory. Checks are
914 * done by ensuring that namei() already traversed the
915 * result of dotdot lookup.
917 if (cnp->cn_flags & ISDOTDOT) {
918 if ((ndp->ni_lcf & (NI_LCF_STRICTRELATIVE | NI_LCF_CAP_DOTDOT))
919 == NI_LCF_STRICTRELATIVE) {
921 if (KTRPOINT(curthread, KTR_CAPFAIL))
922 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
927 if ((cnp->cn_flags & ISLASTCN) != 0 &&
928 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
933 for (pr = cnp->cn_cred->cr_prison; pr != NULL;
935 if (dp == pr->pr_root)
937 if (dp == ndp->ni_rootdir ||
938 dp == ndp->ni_topdir ||
941 ((dp->v_vflag & VV_ROOT) != 0 &&
942 (cnp->cn_flags & NOCROSSMOUNT) != 0)) {
948 if ((dp->v_vflag & VV_ROOT) == 0)
950 if (VN_IS_DOOMED(dp)) { /* forced unmount */
955 dp = dp->v_mount->mnt_vnodecovered;
959 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags |
960 LK_RETRY, ISDOTDOT));
961 error = nameicap_check_dotdot(ndp, dp);
964 if (KTRPOINT(curthread, KTR_CAPFAIL))
965 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
973 * We now have a segment name to search for, and a directory to search.
977 error = mac_vnode_check_lookup(cnp->cn_thread->td_ucred, dp, cnp);
983 ASSERT_VOP_LOCKED(dp, "lookup");
985 * If we have a shared lock we may need to upgrade the lock for the
988 if ((cnp->cn_flags & LOCKPARENT) && (cnp->cn_flags & ISLASTCN) &&
989 dp != vp_crossmp && VOP_ISLOCKED(dp) == LK_SHARED)
990 vn_lock(dp, LK_UPGRADE|LK_RETRY);
991 if (VN_IS_DOOMED(dp)) {
996 * If we're looking up the last component and we need an exclusive
997 * lock, adjust our lkflags.
999 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags))
1000 cnp->cn_lkflags = LK_EXCLUSIVE;
1001 #ifdef NAMEI_DIAGNOSTIC
1002 vn_printf(dp, "lookup in ");
1004 lkflags_save = cnp->cn_lkflags;
1005 cnp->cn_lkflags = compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags,
1007 error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp);
1008 cnp->cn_lkflags = lkflags_save;
1010 KASSERT(ndp->ni_vp == NULL, ("leaf should be empty"));
1011 #ifdef NAMEI_DIAGNOSTIC
1012 printf("not found\n");
1014 if ((error == ENOENT) &&
1015 (dp->v_vflag & VV_ROOT) && (dp->v_mount != NULL) &&
1016 (dp->v_mount->mnt_flag & MNT_UNION)) {
1018 dp = dp->v_mount->mnt_vnodecovered;
1022 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags |
1023 LK_RETRY, cnp->cn_flags));
1024 nameicap_tracker_add(ndp, dp);
1028 if (error == ERELOOKUP) {
1036 if (error != EJUSTRETURN)
1039 * At this point, we know we're at the end of the
1040 * pathname. If creating / renaming, we can consider
1041 * allowing the file or directory to be created / renamed,
1042 * provided we're not on a read-only filesystem.
1048 /* trailing slash only allowed for directories */
1049 if ((cnp->cn_flags & TRAILINGSLASH) &&
1050 !(cnp->cn_flags & WILLBEDIR)) {
1054 if ((cnp->cn_flags & LOCKPARENT) == 0)
1057 * We return with ni_vp NULL to indicate that the entry
1058 * doesn't currently exist, leaving a pointer to the
1059 * (possibly locked) directory vnode in ndp->ni_dvp.
1061 if (cnp->cn_flags & SAVESTART) {
1062 ndp->ni_startdir = ndp->ni_dvp;
1063 VREF(ndp->ni_startdir);
1069 #ifdef NAMEI_DIAGNOSTIC
1075 * Check to see if the vnode has been mounted on;
1076 * if so find the root of the mounted filesystem.
1078 while (dp->v_type == VDIR && (mp = dp->v_mountedhere) &&
1079 (cnp->cn_flags & NOCROSSMOUNT) == 0) {
1080 if (vfs_busy(mp, 0))
1083 if (dp != ndp->ni_dvp)
1087 vrefact(vp_crossmp);
1088 ndp->ni_dvp = vp_crossmp;
1089 error = VFS_ROOT(mp, compute_cn_lkflags(mp, cnp->cn_lkflags,
1090 cnp->cn_flags), &tdp);
1092 if (vn_lock(vp_crossmp, LK_SHARED | LK_NOWAIT))
1093 panic("vp_crossmp exclusively locked or reclaimed");
1098 ndp->ni_vp = dp = tdp;
1102 * Check for symbolic link
1104 if ((dp->v_type == VLNK) &&
1105 ((cnp->cn_flags & FOLLOW) || (cnp->cn_flags & TRAILINGSLASH) ||
1106 *ndp->ni_next == '/')) {
1107 cnp->cn_flags |= ISSYMLINK;
1108 if (VN_IS_DOOMED(dp)) {
1110 * We can't know whether the directory was mounted with
1111 * NOSYMFOLLOW, so we can't follow safely.
1116 if (dp->v_mount->mnt_flag & MNT_NOSYMFOLLOW) {
1121 * Symlink code always expects an unlocked dvp.
1123 if (ndp->ni_dvp != ndp->ni_vp) {
1124 VOP_UNLOCK(ndp->ni_dvp);
1125 ni_dvp_unlocked = 1;
1132 * Not a symbolic link that we will follow. Continue with the
1133 * next component if there is any; otherwise, we're done.
1135 KASSERT((cnp->cn_flags & ISLASTCN) || *ndp->ni_next == '/',
1136 ("lookup: invalid path state."));
1139 ndp->ni_pathlen = prev_ni_pathlen;
1140 ndp->ni_next = prev_ni_next;
1141 if (ndp->ni_dvp != dp)
1147 if (cnp->cn_flags & ISDOTDOT) {
1148 error = nameicap_check_dotdot(ndp, ndp->ni_vp);
1151 if (KTRPOINT(curthread, KTR_CAPFAIL))
1152 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
1157 if (*ndp->ni_next == '/') {
1158 cnp->cn_nameptr = ndp->ni_next;
1159 while (*cnp->cn_nameptr == '/') {
1163 if (ndp->ni_dvp != dp)
1170 * If we're processing a path with a trailing slash,
1171 * check that the end result is a directory.
1173 if ((cnp->cn_flags & TRAILINGSLASH) && dp->v_type != VDIR) {
1178 * Disallow directory write attempts on read-only filesystems.
1181 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
1185 if (cnp->cn_flags & SAVESTART) {
1186 ndp->ni_startdir = ndp->ni_dvp;
1187 VREF(ndp->ni_startdir);
1190 ni_dvp_unlocked = 2;
1191 if (ndp->ni_dvp != dp)
1195 } else if ((cnp->cn_flags & LOCKPARENT) == 0 && ndp->ni_dvp != dp) {
1196 VOP_UNLOCK(ndp->ni_dvp);
1197 ni_dvp_unlocked = 1;
1200 if (cnp->cn_flags & AUDITVNODE1)
1201 AUDIT_ARG_VNODE1(dp);
1202 else if (cnp->cn_flags & AUDITVNODE2)
1203 AUDIT_ARG_VNODE2(dp);
1205 if ((cnp->cn_flags & LOCKLEAF) == 0)
1209 * Because of shared lookup we may have the vnode shared locked, but
1210 * the caller may want it to be exclusively locked.
1212 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags) &&
1213 VOP_ISLOCKED(dp) != LK_EXCLUSIVE) {
1214 vn_lock(dp, LK_UPGRADE | LK_RETRY);
1215 if (VN_IS_DOOMED(dp)) {
1223 if (ni_dvp_unlocked != 2) {
1224 if (dp != ndp->ni_dvp && !ni_dvp_unlocked)
1237 * relookup - lookup a path name component
1238 * Used by lookup to re-acquire things.
1241 relookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp)
1243 struct vnode *dp = NULL; /* the directory we are searching */
1244 int wantparent; /* 1 => wantparent or lockparent flag */
1245 int rdonly; /* lookup read-only flag bit */
1248 KASSERT(cnp->cn_flags & ISLASTCN,
1249 ("relookup: Not given last component."));
1251 * Setup: break out flag bits into variables.
1253 wantparent = cnp->cn_flags & (LOCKPARENT|WANTPARENT);
1254 KASSERT(wantparent, ("relookup: parent not wanted."));
1255 rdonly = cnp->cn_flags & RDONLY;
1256 cnp->cn_flags &= ~ISSYMLINK;
1258 cnp->cn_lkflags = LK_EXCLUSIVE;
1259 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY);
1262 * Search a new directory.
1264 * The last component of the filename is left accessible via
1265 * cnp->cn_nameptr for callers that need the name. Callers needing
1266 * the name set the SAVENAME flag. When done, they assume
1267 * responsibility for freeing the pathname buffer.
1269 #ifdef NAMEI_DIAGNOSTIC
1270 printf("{%s}: ", cnp->cn_nameptr);
1274 * Check for "" which represents the root directory after slash
1277 if (cnp->cn_nameptr[0] == '\0') {
1279 * Support only LOOKUP for "/" because lookup()
1280 * can't succeed for CREATE, DELETE and RENAME.
1282 KASSERT(cnp->cn_nameiop == LOOKUP, ("nameiop must be LOOKUP"));
1283 KASSERT(dp->v_type == VDIR, ("dp is not a directory"));
1285 if (!(cnp->cn_flags & LOCKLEAF))
1288 /* XXX This should probably move to the top of function. */
1289 if (cnp->cn_flags & SAVESTART)
1290 panic("lookup: SAVESTART");
1294 if (cnp->cn_flags & ISDOTDOT)
1295 panic ("relookup: lookup on dot-dot");
1298 * We now have a segment name to search for, and a directory to search.
1300 #ifdef NAMEI_DIAGNOSTIC
1301 vn_printf(dp, "search in ");
1303 if ((error = VOP_LOOKUP(dp, vpp, cnp)) != 0) {
1304 KASSERT(*vpp == NULL, ("leaf should be empty"));
1305 if (error != EJUSTRETURN)
1308 * If creating and at end of pathname, then can consider
1309 * allowing file to be created.
1315 /* ASSERT(dvp == ndp->ni_startdir) */
1316 if (cnp->cn_flags & SAVESTART)
1318 if ((cnp->cn_flags & LOCKPARENT) == 0)
1321 * We return with ni_vp NULL to indicate that the entry
1322 * doesn't currently exist, leaving a pointer to the
1323 * (possibly locked) directory vnode in ndp->ni_dvp.
1331 * Disallow directory write attempts on read-only filesystems.
1334 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
1343 * Set the parent lock/ref state to the requested state.
1345 if ((cnp->cn_flags & LOCKPARENT) == 0 && dvp != dp) {
1350 } else if (!wantparent)
1353 * Check for symbolic link
1355 KASSERT(dp->v_type != VLNK || !(cnp->cn_flags & FOLLOW),
1356 ("relookup: symlink found.\n"));
1358 /* ASSERT(dvp == ndp->ni_startdir) */
1359 if (cnp->cn_flags & SAVESTART)
1362 if ((cnp->cn_flags & LOCKLEAF) == 0)
1372 * Free data allocated by namei(); see namei(9) for details.
1375 NDFREE_PNBUF(struct nameidata *ndp)
1378 if ((ndp->ni_cnd.cn_flags & HASBUF) != 0) {
1379 uma_zfree(namei_zone, ndp->ni_cnd.cn_pnbuf);
1380 ndp->ni_cnd.cn_flags &= ~HASBUF;
1385 (NDFREE)(struct nameidata *ndp, const u_int flags)
1393 if (!(flags & NDF_NO_FREE_PNBUF)) {
1396 if (!(flags & NDF_NO_VP_UNLOCK) &&
1397 (ndp->ni_cnd.cn_flags & LOCKLEAF) && ndp->ni_vp)
1399 if (!(flags & NDF_NO_DVP_UNLOCK) &&
1400 (ndp->ni_cnd.cn_flags & LOCKPARENT) &&
1401 ndp->ni_dvp != ndp->ni_vp)
1403 if (!(flags & NDF_NO_VP_RELE) && ndp->ni_vp) {
1412 VOP_UNLOCK(ndp->ni_vp);
1413 if (!(flags & NDF_NO_DVP_RELE) &&
1414 (ndp->ni_cnd.cn_flags & (LOCKPARENT|WANTPARENT))) {
1423 VOP_UNLOCK(ndp->ni_dvp);
1424 if (!(flags & NDF_NO_STARTDIR_RELE) &&
1425 (ndp->ni_cnd.cn_flags & SAVESTART)) {
1426 vrele(ndp->ni_startdir);
1427 ndp->ni_startdir = NULL;
1432 * Determine if there is a suitable alternate filename under the specified
1433 * prefix for the specified path. If the create flag is set, then the
1434 * alternate prefix will be used so long as the parent directory exists.
1435 * This is used by the various compatibility ABIs so that Linux binaries prefer
1436 * files under /compat/linux for example. The chosen path (whether under
1437 * the prefix or under /) is returned in a kernel malloc'd buffer pointed
1438 * to by pathbuf. The caller is responsible for free'ing the buffer from
1439 * the M_TEMP bucket if one is returned.
1442 kern_alternate_path(struct thread *td, const char *prefix, const char *path,
1443 enum uio_seg pathseg, char **pathbuf, int create, int dirfd)
1445 struct nameidata nd, ndroot;
1446 char *ptr, *buf, *cp;
1450 buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
1453 /* Copy the prefix into the new pathname as a starting point. */
1454 len = strlcpy(buf, prefix, MAXPATHLEN);
1455 if (len >= MAXPATHLEN) {
1460 sz = MAXPATHLEN - len;
1463 /* Append the filename to the prefix. */
1464 if (pathseg == UIO_SYSSPACE)
1465 error = copystr(path, ptr, sz, &len);
1467 error = copyinstr(path, ptr, sz, &len);
1475 /* Only use a prefix with absolute pathnames. */
1481 if (dirfd != AT_FDCWD) {
1483 * We want the original because the "prefix" is
1484 * included in the already opened dirfd.
1486 bcopy(ptr, buf, len);
1491 * We know that there is a / somewhere in this pathname.
1492 * Search backwards for it, to find the file's parent dir
1493 * to see if it exists in the alternate tree. If it does,
1494 * and we want to create a file (cflag is set). We don't
1495 * need to worry about the root comparison in this case.
1499 for (cp = &ptr[len] - 1; *cp != '/'; cp--);
1502 NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_SYSSPACE, buf, td);
1508 NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_SYSSPACE, buf, td);
1515 * We now compare the vnode of the prefix to the one
1516 * vnode asked. If they resolve to be the same, then we
1517 * ignore the match so that the real root gets used.
1518 * This avoids the problem of traversing "../.." to find the
1519 * root directory and never finding it, because "/" resolves
1520 * to the emulation root directory. This is expensive :-(
1522 NDINIT(&ndroot, LOOKUP, FOLLOW, UIO_SYSSPACE, prefix,
1525 /* We shouldn't ever get an error from this namei(). */
1526 error = namei(&ndroot);
1528 if (nd.ni_vp == ndroot.ni_vp)
1531 NDFREE(&ndroot, NDF_ONLY_PNBUF);
1532 vrele(ndroot.ni_vp);
1536 NDFREE(&nd, NDF_ONLY_PNBUF);
1540 /* If there was an error, use the original path name. */
1542 bcopy(ptr, buf, len);