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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16 * notice, this list of conditions and the following disclaimer.
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33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * @(#)vfs_lookup.c 8.4 (Berkeley) 2/16/94
39 #include <sys/cdefs.h>
40 __FBSDID("$FreeBSD$");
42 #include "opt_capsicum.h"
43 #include "opt_ktrace.h"
45 #include <sys/param.h>
46 #include <sys/systm.h>
47 #include <sys/kernel.h>
48 #include <sys/capsicum.h>
49 #include <sys/fcntl.h>
52 #include <sys/mutex.h>
53 #include <sys/namei.h>
54 #include <sys/vnode.h>
55 #include <sys/mount.h>
56 #include <sys/filedesc.h>
59 #include <sys/syscallsubr.h>
60 #include <sys/sysctl.h>
62 #include <sys/ktrace.h>
65 #include <security/audit/audit.h>
66 #include <security/mac/mac_framework.h>
70 #define NAMEI_DIAGNOSTIC 1
71 #undef NAMEI_DIAGNOSTIC
73 SDT_PROVIDER_DECLARE(vfs);
74 SDT_PROBE_DEFINE3(vfs, namei, lookup, entry, "struct vnode *", "char *",
76 SDT_PROBE_DEFINE2(vfs, namei, lookup, return, "int", "struct vnode *");
78 /* Allocation zone for namei. */
79 uma_zone_t namei_zone;
81 /* Placeholder vnode for mp traversal. */
82 static struct vnode *vp_crossmp;
85 crossmp_vop_islocked(struct vop_islocked_args *ap)
92 crossmp_vop_lock1(struct vop_lock1_args *ap)
95 struct lock *lk __unused;
96 const char *file __unused;
97 int flags, line __unused;
105 if ((flags & LK_SHARED) == 0)
106 panic("invalid lock request for crossmp");
108 WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER, file, line,
109 flags & LK_INTERLOCK ? &VI_MTX(vp)->lock_object : NULL);
110 WITNESS_LOCK(&lk->lock_object, 0, file, line);
111 if ((flags & LK_INTERLOCK) != 0)
113 LOCK_LOG_LOCK("SLOCK", &lk->lock_object, 0, 0, ap->a_file, line);
118 crossmp_vop_unlock(struct vop_unlock_args *ap)
121 struct lock *lk __unused;
128 if ((flags & LK_INTERLOCK) != 0)
130 WITNESS_UNLOCK(&lk->lock_object, 0, LOCK_FILE, LOCK_LINE);
131 LOCK_LOG_LOCK("SUNLOCK", &lk->lock_object, 0, 0, LOCK_FILE,
136 static struct vop_vector crossmp_vnodeops = {
137 .vop_default = &default_vnodeops,
138 .vop_islocked = crossmp_vop_islocked,
139 .vop_lock1 = crossmp_vop_lock1,
140 .vop_unlock = crossmp_vop_unlock,
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 getnewvnode("crossmp", NULL, &crossmp_vnodeops, &vp_crossmp);
161 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nameiinit, NULL);
163 static int lookup_cap_dotdot = 1;
164 SYSCTL_INT(_vfs, OID_AUTO, lookup_cap_dotdot, CTLFLAG_RWTUN,
165 &lookup_cap_dotdot, 0,
166 "enables \"..\" components in path lookup in capability mode");
167 static int lookup_cap_dotdot_nonlocal = 1;
168 SYSCTL_INT(_vfs, OID_AUTO, lookup_cap_dotdot_nonlocal, CTLFLAG_RWTUN,
169 &lookup_cap_dotdot_nonlocal, 0,
170 "enables \"..\" components in path lookup in capability mode "
171 "on non-local mount");
174 nameicap_tracker_add(struct nameidata *ndp, struct vnode *dp)
176 struct nameicap_tracker *nt;
178 if ((ndp->ni_lcf & NI_LCF_CAP_DOTDOT) == 0 || dp->v_type != VDIR)
180 nt = uma_zalloc(nt_zone, M_WAITOK);
183 TAILQ_INSERT_TAIL(&ndp->ni_cap_tracker, nt, nm_link);
187 nameicap_cleanup(struct nameidata *ndp)
189 struct nameicap_tracker *nt, *nt1;
191 KASSERT(TAILQ_EMPTY(&ndp->ni_cap_tracker) ||
192 (ndp->ni_lcf & NI_LCF_CAP_DOTDOT) != 0, ("not strictrelative"));
193 TAILQ_FOREACH_SAFE(nt, &ndp->ni_cap_tracker, nm_link, nt1) {
194 TAILQ_REMOVE(&ndp->ni_cap_tracker, nt, nm_link);
196 uma_zfree(nt_zone, nt);
201 * For dotdot lookups in capability mode, only allow the component
202 * lookup to succeed if the resulting directory was already traversed
203 * during the operation. Also fail dotdot lookups for non-local
204 * filesystems, where external agents might assist local lookups to
205 * escape the compartment.
208 nameicap_check_dotdot(struct nameidata *ndp, struct vnode *dp)
210 struct nameicap_tracker *nt;
213 if ((ndp->ni_lcf & NI_LCF_CAP_DOTDOT) == 0 || dp == NULL ||
217 if (lookup_cap_dotdot_nonlocal == 0 && mp != NULL &&
218 (mp->mnt_flag & MNT_LOCAL) == 0)
219 return (ENOTCAPABLE);
220 TAILQ_FOREACH_REVERSE(nt, &ndp->ni_cap_tracker, nameicap_tracker_head,
225 return (ENOTCAPABLE);
229 namei_cleanup_cnp(struct componentname *cnp)
232 uma_zfree(namei_zone, cnp->cn_pnbuf);
234 cnp->cn_pnbuf = NULL;
235 cnp->cn_nameptr = NULL;
240 namei_handle_root(struct nameidata *ndp, struct vnode **dpp)
242 struct componentname *cnp;
245 if ((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) != 0 ||
246 (cnp->cn_flags & BENEATH) != 0) {
248 if (KTRPOINT(curthread, KTR_CAPFAIL))
249 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
251 return (ENOTCAPABLE);
253 while (*(cnp->cn_nameptr) == '/') {
257 *dpp = ndp->ni_rootdir;
263 * Convert a pathname into a pointer to a locked vnode.
265 * The FOLLOW flag is set when symbolic links are to be followed
266 * when they occur at the end of the name translation process.
267 * Symbolic links are always followed for all other pathname
268 * components other than the last.
270 * The segflg defines whether the name is to be copied from user
271 * space or kernel space.
273 * Overall outline of namei:
276 * get starting directory
277 * while (!done && !error) {
278 * call lookup to search path.
279 * if symbolic link, massage name in buffer and continue
283 namei(struct nameidata *ndp)
285 struct filedesc *fdp; /* pointer to file descriptor state */
286 char *cp; /* pointer into pathname argument */
287 struct vnode *dp; /* the directory we are searching */
288 struct iovec aiov; /* uio for reading symbolic links */
289 struct componentname *cnp;
294 int error, linklen, startdir_used;
299 ndp->ni_cnd.cn_cred = ndp->ni_cnd.cn_thread->td_ucred;
300 KASSERT(cnp->cn_cred && p, ("namei: bad cred/proc"));
301 KASSERT((cnp->cn_nameiop & (~OPMASK)) == 0,
302 ("namei: nameiop contaminated with flags"));
303 KASSERT((cnp->cn_flags & OPMASK) == 0,
304 ("namei: flags contaminated with nameiops"));
305 MPASS(ndp->ni_startdir == NULL || ndp->ni_startdir->v_type == VDIR ||
306 ndp->ni_startdir->v_type == VBAD);
308 TAILQ_INIT(&ndp->ni_cap_tracker);
311 /* We will set this ourselves if we need it. */
312 cnp->cn_flags &= ~TRAILINGSLASH;
315 * Get a buffer for the name to be translated, and copy the
316 * name into the buffer.
318 if ((cnp->cn_flags & HASBUF) == 0)
319 cnp->cn_pnbuf = uma_zalloc(namei_zone, M_WAITOK);
320 if (ndp->ni_segflg == UIO_SYSSPACE)
321 error = copystr(ndp->ni_dirp, cnp->cn_pnbuf, MAXPATHLEN,
324 error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf, MAXPATHLEN,
328 * Don't allow empty pathnames.
330 if (error == 0 && *cnp->cn_pnbuf == '\0')
333 #ifdef CAPABILITY_MODE
335 * In capability mode, lookups must be restricted to happen in
336 * the subtree with the root specified by the file descriptor:
337 * - The root must be real file descriptor, not the pseudo-descriptor
339 * - The passed path must be relative and not absolute.
340 * - If lookup_cap_dotdot is disabled, path must not contain the
342 * - If lookup_cap_dotdot is enabled, we verify that all '..'
343 * components lookups result in the directories which were
344 * previously walked by us, which prevents an escape from
347 if (error == 0 && IN_CAPABILITY_MODE(td) &&
348 (cnp->cn_flags & NOCAPCHECK) == 0) {
349 ndp->ni_lcf |= NI_LCF_STRICTRELATIVE;
350 if (ndp->ni_dirfd == AT_FDCWD) {
352 if (KTRPOINT(td, KTR_CAPFAIL))
353 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
360 namei_cleanup_cnp(cnp);
366 if (KTRPOINT(td, KTR_NAMEI)) {
367 KASSERT(cnp->cn_thread == curthread,
368 ("namei not using curthread"));
369 ktrnamei(cnp->cn_pnbuf);
373 * Get starting point for the translation.
376 ndp->ni_rootdir = fdp->fd_rdir;
377 vrefact(ndp->ni_rootdir);
378 ndp->ni_topdir = fdp->fd_jdir;
381 * If we are auditing the kernel pathname, save the user pathname.
383 if (cnp->cn_flags & AUDITVNODE1)
384 AUDIT_ARG_UPATH1(td, ndp->ni_dirfd, cnp->cn_pnbuf);
385 if (cnp->cn_flags & AUDITVNODE2)
386 AUDIT_ARG_UPATH2(td, ndp->ni_dirfd, cnp->cn_pnbuf);
390 cnp->cn_nameptr = cnp->cn_pnbuf;
391 if (cnp->cn_pnbuf[0] == '/') {
392 error = namei_handle_root(ndp, &dp);
394 if (ndp->ni_startdir != NULL) {
395 dp = ndp->ni_startdir;
397 } else if (ndp->ni_dirfd == AT_FDCWD) {
401 rights = ndp->ni_rightsneeded;
402 cap_rights_set(&rights, CAP_LOOKUP);
404 if (cnp->cn_flags & AUDITVNODE1)
405 AUDIT_ARG_ATFD1(ndp->ni_dirfd);
406 if (cnp->cn_flags & AUDITVNODE2)
407 AUDIT_ARG_ATFD2(ndp->ni_dirfd);
408 error = fgetvp_rights(td, ndp->ni_dirfd,
409 &rights, &ndp->ni_filecaps, &dp);
414 * If file descriptor doesn't have all rights,
415 * all lookups relative to it must also be
419 if (!cap_rights_contains(&ndp->ni_filecaps.fc_rights,
421 ndp->ni_filecaps.fc_fcntls != CAP_FCNTL_ALL ||
422 ndp->ni_filecaps.fc_nioctls != -1) {
423 ndp->ni_lcf |= NI_LCF_STRICTRELATIVE;
427 if (error == 0 && dp->v_type != VDIR)
430 FILEDESC_SUNLOCK(fdp);
431 if (ndp->ni_startdir != NULL && !startdir_used)
432 vrele(ndp->ni_startdir);
438 if (((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) != 0 &&
439 lookup_cap_dotdot != 0) ||
440 ((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) == 0 &&
441 (cnp->cn_flags & BENEATH) != 0))
442 ndp->ni_lcf |= NI_LCF_CAP_DOTDOT;
443 SDT_PROBE3(vfs, namei, lookup, entry, dp, cnp->cn_pnbuf,
446 ndp->ni_startdir = dp;
451 * If not a symbolic link, we're done.
453 if ((cnp->cn_flags & ISSYMLINK) == 0) {
454 vrele(ndp->ni_rootdir);
455 if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) {
456 namei_cleanup_cnp(cnp);
458 cnp->cn_flags |= HASBUF;
459 nameicap_cleanup(ndp);
460 SDT_PROBE2(vfs, namei, lookup, return, 0, ndp->ni_vp);
463 if (ndp->ni_loopcnt++ >= MAXSYMLINKS) {
468 if ((cnp->cn_flags & NOMACCHECK) == 0) {
469 error = mac_vnode_check_readlink(td->td_ucred,
475 if (ndp->ni_pathlen > 1)
476 cp = uma_zalloc(namei_zone, M_WAITOK);
480 aiov.iov_len = MAXPATHLEN;
481 auio.uio_iov = &aiov;
484 auio.uio_rw = UIO_READ;
485 auio.uio_segflg = UIO_SYSSPACE;
487 auio.uio_resid = MAXPATHLEN;
488 error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred);
490 if (ndp->ni_pathlen > 1)
491 uma_zfree(namei_zone, cp);
494 linklen = MAXPATHLEN - auio.uio_resid;
496 if (ndp->ni_pathlen > 1)
497 uma_zfree(namei_zone, cp);
501 if (linklen + ndp->ni_pathlen > MAXPATHLEN) {
502 if (ndp->ni_pathlen > 1)
503 uma_zfree(namei_zone, cp);
504 error = ENAMETOOLONG;
507 if (ndp->ni_pathlen > 1) {
508 bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen);
509 uma_zfree(namei_zone, cnp->cn_pnbuf);
512 cnp->cn_pnbuf[linklen] = '\0';
513 ndp->ni_pathlen += linklen;
517 * Check if root directory should replace current directory.
519 cnp->cn_nameptr = cnp->cn_pnbuf;
520 if (*(cnp->cn_nameptr) == '/') {
522 error = namei_handle_root(ndp, &dp);
531 vrele(ndp->ni_rootdir);
532 namei_cleanup_cnp(cnp);
533 nameicap_cleanup(ndp);
534 SDT_PROBE2(vfs, namei, lookup, return, error, NULL);
539 compute_cn_lkflags(struct mount *mp, int lkflags, int cnflags)
542 if (mp == NULL || ((lkflags & LK_SHARED) &&
543 (!(mp->mnt_kern_flag & MNTK_LOOKUP_SHARED) ||
544 ((cnflags & ISDOTDOT) &&
545 (mp->mnt_kern_flag & MNTK_LOOKUP_EXCL_DOTDOT))))) {
546 lkflags &= ~LK_SHARED;
547 lkflags |= LK_EXCLUSIVE;
549 lkflags |= LK_NODDLKTREAT;
554 needs_exclusive_leaf(struct mount *mp, int flags)
558 * Intermediate nodes can use shared locks, we only need to
559 * force an exclusive lock for leaf nodes.
561 if ((flags & (ISLASTCN | LOCKLEAF)) != (ISLASTCN | LOCKLEAF))
564 /* Always use exclusive locks if LOCKSHARED isn't set. */
565 if (!(flags & LOCKSHARED))
569 * For lookups during open(), if the mount point supports
570 * extended shared operations, then use a shared lock for the
571 * leaf node, otherwise use an exclusive lock.
573 if ((flags & ISOPEN) != 0)
574 return (!MNT_EXTENDED_SHARED(mp));
577 * Lookup requests outside of open() that specify LOCKSHARED
578 * only need a shared lock on the leaf vnode.
585 * This is a very central and rather complicated routine.
587 * The pathname is pointed to by ni_ptr and is of length ni_pathlen.
588 * The starting directory is taken from ni_startdir. The pathname is
589 * descended until done, or a symbolic link is encountered. The variable
590 * ni_more is clear if the path is completed; it is set to one if a
591 * symbolic link needing interpretation is encountered.
593 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on
594 * whether the name is to be looked up, created, renamed, or deleted.
595 * When CREATE, RENAME, or DELETE is specified, information usable in
596 * creating, renaming, or deleting a directory entry may be calculated.
597 * If flag has LOCKPARENT or'ed into it, the parent directory is returned
598 * locked. If flag has WANTPARENT or'ed into it, the parent directory is
599 * returned unlocked. Otherwise the parent directory is not returned. If
600 * the target of the pathname exists and LOCKLEAF is or'ed into the flag
601 * the target is returned locked, otherwise it is returned unlocked.
602 * When creating or renaming and LOCKPARENT is specified, the target may not
603 * be ".". When deleting and LOCKPARENT is specified, the target may be ".".
605 * Overall outline of lookup:
608 * identify next component of name at ndp->ni_ptr
609 * handle degenerate case where name is null string
610 * if .. and crossing mount points and on mounted filesys, find parent
611 * call VOP_LOOKUP routine for next component name
612 * directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set
613 * component vnode returned in ni_vp (if it exists), locked.
614 * if result vnode is mounted on and crossing mount points,
615 * find mounted on vnode
616 * if more components of name, do next level at dirloop
617 * return the answer in ni_vp, locked if LOCKLEAF set
618 * if LOCKPARENT set, return locked parent in ni_dvp
619 * if WANTPARENT set, return unlocked parent in ni_dvp
622 lookup(struct nameidata *ndp)
624 char *cp; /* pointer into pathname argument */
625 char *prev_ni_next; /* saved ndp->ni_next */
626 struct vnode *dp = NULL; /* the directory we are searching */
627 struct vnode *tdp; /* saved dp */
628 struct mount *mp; /* mount table entry */
630 size_t prev_ni_pathlen; /* saved ndp->ni_pathlen */
631 int docache; /* == 0 do not cache last component */
632 int wantparent; /* 1 => wantparent or lockparent flag */
633 int rdonly; /* lookup read-only flag bit */
635 int dpunlocked = 0; /* dp has already been unlocked */
636 int relookup = 0; /* do not consume the path component */
637 struct componentname *cnp = &ndp->ni_cnd;
642 * Setup: break out flag bits into variables.
645 wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT);
646 KASSERT(cnp->cn_nameiop == LOOKUP || wantparent,
647 ("CREATE, DELETE, RENAME require LOCKPARENT or WANTPARENT."));
648 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE;
649 if (cnp->cn_nameiop == DELETE ||
650 (wantparent && cnp->cn_nameiop != CREATE &&
651 cnp->cn_nameiop != LOOKUP))
653 rdonly = cnp->cn_flags & RDONLY;
654 cnp->cn_flags &= ~ISSYMLINK;
657 * We use shared locks until we hit the parent of the last cn then
658 * we adjust based on the requesting flags.
660 cnp->cn_lkflags = LK_SHARED;
661 dp = ndp->ni_startdir;
662 ndp->ni_startdir = NULLVP;
664 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | LK_RETRY,
669 * Search a new directory.
671 * The last component of the filename is left accessible via
672 * cnp->cn_nameptr for callers that need the name. Callers needing
673 * the name set the SAVENAME flag. When done, they assume
674 * responsibility for freeing the pathname buffer.
676 for (cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++)
678 cnp->cn_namelen = cp - cnp->cn_nameptr;
679 if (cnp->cn_namelen > NAME_MAX) {
680 error = ENAMETOOLONG;
683 #ifdef NAMEI_DIAGNOSTIC
686 printf("{%s}: ", cnp->cn_nameptr);
689 prev_ni_pathlen = ndp->ni_pathlen;
690 ndp->ni_pathlen -= cnp->cn_namelen;
691 KASSERT(ndp->ni_pathlen <= PATH_MAX,
692 ("%s: ni_pathlen underflow to %zd\n", __func__, ndp->ni_pathlen));
693 prev_ni_next = ndp->ni_next;
697 * Replace multiple slashes by a single slash and trailing slashes
698 * by a null. This must be done before VOP_LOOKUP() because some
699 * fs's don't know about trailing slashes. Remember if there were
700 * trailing slashes to handle symlinks, existing non-directories
701 * and non-existing files that won't be directories specially later.
703 while (*cp == '/' && (cp[1] == '/' || cp[1] == '\0')) {
707 *ndp->ni_next = '\0';
708 cnp->cn_flags |= TRAILINGSLASH;
713 cnp->cn_flags |= MAKEENTRY;
714 if (*cp == '\0' && docache == 0)
715 cnp->cn_flags &= ~MAKEENTRY;
716 if (cnp->cn_namelen == 2 &&
717 cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.')
718 cnp->cn_flags |= ISDOTDOT;
720 cnp->cn_flags &= ~ISDOTDOT;
721 if (*ndp->ni_next == 0)
722 cnp->cn_flags |= ISLASTCN;
724 cnp->cn_flags &= ~ISLASTCN;
726 if ((cnp->cn_flags & ISLASTCN) != 0 &&
727 cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.' &&
728 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
733 nameicap_tracker_add(ndp, dp);
736 * Check for degenerate name (e.g. / or "")
737 * which is a way of talking about a directory,
738 * e.g. like "/." or ".".
740 if (cnp->cn_nameptr[0] == '\0') {
741 if (dp->v_type != VDIR) {
745 if (cnp->cn_nameiop != LOOKUP) {
755 if (cnp->cn_flags & AUDITVNODE1)
756 AUDIT_ARG_VNODE1(dp);
757 else if (cnp->cn_flags & AUDITVNODE2)
758 AUDIT_ARG_VNODE2(dp);
760 if (!(cnp->cn_flags & (LOCKPARENT | LOCKLEAF)))
762 /* XXX This should probably move to the top of function. */
763 if (cnp->cn_flags & SAVESTART)
764 panic("lookup: SAVESTART");
769 * Handle "..": five special cases.
770 * 0. If doing a capability lookup and lookup_cap_dotdot is
771 * disabled, return ENOTCAPABLE.
772 * 1. Return an error if this is the last component of
773 * the name and the operation is DELETE or RENAME.
774 * 2. If at root directory (e.g. after chroot)
775 * or at absolute root directory
776 * then ignore it so can't get out.
777 * 3. If this vnode is the root of a mounted
778 * filesystem, then replace it with the
779 * vnode which was mounted on so we take the
780 * .. in the other filesystem.
781 * 4. If the vnode is the top directory of
782 * the jail or chroot, don't let them out.
783 * 5. If doing a capability lookup and lookup_cap_dotdot is
784 * enabled, return ENOTCAPABLE if the lookup would escape
785 * from the initial file descriptor directory. Checks are
786 * done by ensuring that namei() already traversed the
787 * result of dotdot lookup.
789 if (cnp->cn_flags & ISDOTDOT) {
790 if ((ndp->ni_lcf & (NI_LCF_STRICTRELATIVE | NI_LCF_CAP_DOTDOT))
791 == NI_LCF_STRICTRELATIVE) {
793 if (KTRPOINT(curthread, KTR_CAPFAIL))
794 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
799 if ((cnp->cn_flags & ISLASTCN) != 0 &&
800 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
805 for (pr = cnp->cn_cred->cr_prison; pr != NULL;
807 if (dp == pr->pr_root)
809 if (dp == ndp->ni_rootdir ||
810 dp == ndp->ni_topdir ||
813 ((dp->v_vflag & VV_ROOT) != 0 &&
814 (cnp->cn_flags & NOCROSSMOUNT) != 0)) {
820 if ((dp->v_vflag & VV_ROOT) == 0)
822 if (dp->v_iflag & VI_DOOMED) { /* forced unmount */
827 dp = dp->v_mount->mnt_vnodecovered;
831 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags |
832 LK_RETRY, ISDOTDOT));
833 error = nameicap_check_dotdot(ndp, dp);
836 if (KTRPOINT(curthread, KTR_CAPFAIL))
837 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
845 * We now have a segment name to search for, and a directory to search.
849 if ((cnp->cn_flags & NOMACCHECK) == 0) {
850 error = mac_vnode_check_lookup(cnp->cn_thread->td_ucred, dp,
858 ASSERT_VOP_LOCKED(dp, "lookup");
860 * If we have a shared lock we may need to upgrade the lock for the
863 if ((cnp->cn_flags & LOCKPARENT) && (cnp->cn_flags & ISLASTCN) &&
864 dp != vp_crossmp && VOP_ISLOCKED(dp) == LK_SHARED)
865 vn_lock(dp, LK_UPGRADE|LK_RETRY);
866 if ((dp->v_iflag & VI_DOOMED) != 0) {
871 * If we're looking up the last component and we need an exclusive
872 * lock, adjust our lkflags.
874 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags))
875 cnp->cn_lkflags = LK_EXCLUSIVE;
876 #ifdef NAMEI_DIAGNOSTIC
877 vn_printf(dp, "lookup in ");
879 lkflags_save = cnp->cn_lkflags;
880 cnp->cn_lkflags = compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags,
882 error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp);
883 cnp->cn_lkflags = lkflags_save;
885 KASSERT(ndp->ni_vp == NULL, ("leaf should be empty"));
886 #ifdef NAMEI_DIAGNOSTIC
887 printf("not found\n");
889 if ((error == ENOENT) &&
890 (dp->v_vflag & VV_ROOT) && (dp->v_mount != NULL) &&
891 (dp->v_mount->mnt_flag & MNT_UNION)) {
893 dp = dp->v_mount->mnt_vnodecovered;
897 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags |
898 LK_RETRY, cnp->cn_flags));
899 nameicap_tracker_add(ndp, dp);
903 if (error == ERELOOKUP) {
911 if (error != EJUSTRETURN)
914 * At this point, we know we're at the end of the
915 * pathname. If creating / renaming, we can consider
916 * allowing the file or directory to be created / renamed,
917 * provided we're not on a read-only filesystem.
923 /* trailing slash only allowed for directories */
924 if ((cnp->cn_flags & TRAILINGSLASH) &&
925 !(cnp->cn_flags & WILLBEDIR)) {
929 if ((cnp->cn_flags & LOCKPARENT) == 0)
932 * We return with ni_vp NULL to indicate that the entry
933 * doesn't currently exist, leaving a pointer to the
934 * (possibly locked) directory vnode in ndp->ni_dvp.
936 if (cnp->cn_flags & SAVESTART) {
937 ndp->ni_startdir = ndp->ni_dvp;
938 VREF(ndp->ni_startdir);
944 #ifdef NAMEI_DIAGNOSTIC
950 * Check to see if the vnode has been mounted on;
951 * if so find the root of the mounted filesystem.
953 while (dp->v_type == VDIR && (mp = dp->v_mountedhere) &&
954 (cnp->cn_flags & NOCROSSMOUNT) == 0) {
958 if (dp != ndp->ni_dvp)
963 ndp->ni_dvp = vp_crossmp;
964 error = VFS_ROOT(mp, compute_cn_lkflags(mp, cnp->cn_lkflags,
965 cnp->cn_flags), &tdp);
967 if (vn_lock(vp_crossmp, LK_SHARED | LK_NOWAIT))
968 panic("vp_crossmp exclusively locked or reclaimed");
973 ndp->ni_vp = dp = tdp;
977 * Check for symbolic link
979 if ((dp->v_type == VLNK) &&
980 ((cnp->cn_flags & FOLLOW) || (cnp->cn_flags & TRAILINGSLASH) ||
981 *ndp->ni_next == '/')) {
982 cnp->cn_flags |= ISSYMLINK;
983 if (dp->v_iflag & VI_DOOMED) {
985 * We can't know whether the directory was mounted with
986 * NOSYMFOLLOW, so we can't follow safely.
991 if (dp->v_mount->mnt_flag & MNT_NOSYMFOLLOW) {
996 * Symlink code always expects an unlocked dvp.
998 if (ndp->ni_dvp != ndp->ni_vp) {
999 VOP_UNLOCK(ndp->ni_dvp, 0);
1000 ni_dvp_unlocked = 1;
1007 * Not a symbolic link that we will follow. Continue with the
1008 * next component if there is any; otherwise, we're done.
1010 KASSERT((cnp->cn_flags & ISLASTCN) || *ndp->ni_next == '/',
1011 ("lookup: invalid path state."));
1014 ndp->ni_pathlen = prev_ni_pathlen;
1015 ndp->ni_next = prev_ni_next;
1016 if (ndp->ni_dvp != dp)
1022 if (cnp->cn_flags & ISDOTDOT) {
1023 error = nameicap_check_dotdot(ndp, ndp->ni_vp);
1026 if (KTRPOINT(curthread, KTR_CAPFAIL))
1027 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
1032 if (*ndp->ni_next == '/') {
1033 cnp->cn_nameptr = ndp->ni_next;
1034 while (*cnp->cn_nameptr == '/') {
1038 if (ndp->ni_dvp != dp)
1045 * If we're processing a path with a trailing slash,
1046 * check that the end result is a directory.
1048 if ((cnp->cn_flags & TRAILINGSLASH) && dp->v_type != VDIR) {
1053 * Disallow directory write attempts on read-only filesystems.
1056 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
1060 if (cnp->cn_flags & SAVESTART) {
1061 ndp->ni_startdir = ndp->ni_dvp;
1062 VREF(ndp->ni_startdir);
1065 ni_dvp_unlocked = 2;
1066 if (ndp->ni_dvp != dp)
1070 } else if ((cnp->cn_flags & LOCKPARENT) == 0 && ndp->ni_dvp != dp) {
1071 VOP_UNLOCK(ndp->ni_dvp, 0);
1072 ni_dvp_unlocked = 1;
1075 if (cnp->cn_flags & AUDITVNODE1)
1076 AUDIT_ARG_VNODE1(dp);
1077 else if (cnp->cn_flags & AUDITVNODE2)
1078 AUDIT_ARG_VNODE2(dp);
1080 if ((cnp->cn_flags & LOCKLEAF) == 0)
1084 * Because of shared lookup we may have the vnode shared locked, but
1085 * the caller may want it to be exclusively locked.
1087 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags) &&
1088 VOP_ISLOCKED(dp) != LK_EXCLUSIVE) {
1089 vn_lock(dp, LK_UPGRADE | LK_RETRY);
1090 if (dp->v_iflag & VI_DOOMED) {
1098 if (ni_dvp_unlocked != 2) {
1099 if (dp != ndp->ni_dvp && !ni_dvp_unlocked)
1112 * relookup - lookup a path name component
1113 * Used by lookup to re-acquire things.
1116 relookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp)
1118 struct vnode *dp = NULL; /* the directory we are searching */
1119 int wantparent; /* 1 => wantparent or lockparent flag */
1120 int rdonly; /* lookup read-only flag bit */
1123 KASSERT(cnp->cn_flags & ISLASTCN,
1124 ("relookup: Not given last component."));
1126 * Setup: break out flag bits into variables.
1128 wantparent = cnp->cn_flags & (LOCKPARENT|WANTPARENT);
1129 KASSERT(wantparent, ("relookup: parent not wanted."));
1130 rdonly = cnp->cn_flags & RDONLY;
1131 cnp->cn_flags &= ~ISSYMLINK;
1133 cnp->cn_lkflags = LK_EXCLUSIVE;
1134 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY);
1137 * Search a new directory.
1139 * The last component of the filename is left accessible via
1140 * cnp->cn_nameptr for callers that need the name. Callers needing
1141 * the name set the SAVENAME flag. When done, they assume
1142 * responsibility for freeing the pathname buffer.
1144 #ifdef NAMEI_DIAGNOSTIC
1145 printf("{%s}: ", cnp->cn_nameptr);
1149 * Check for "" which represents the root directory after slash
1152 if (cnp->cn_nameptr[0] == '\0') {
1154 * Support only LOOKUP for "/" because lookup()
1155 * can't succeed for CREATE, DELETE and RENAME.
1157 KASSERT(cnp->cn_nameiop == LOOKUP, ("nameiop must be LOOKUP"));
1158 KASSERT(dp->v_type == VDIR, ("dp is not a directory"));
1160 if (!(cnp->cn_flags & LOCKLEAF))
1163 /* XXX This should probably move to the top of function. */
1164 if (cnp->cn_flags & SAVESTART)
1165 panic("lookup: SAVESTART");
1169 if (cnp->cn_flags & ISDOTDOT)
1170 panic ("relookup: lookup on dot-dot");
1173 * We now have a segment name to search for, and a directory to search.
1175 #ifdef NAMEI_DIAGNOSTIC
1176 vn_printf(dp, "search in ");
1178 if ((error = VOP_LOOKUP(dp, vpp, cnp)) != 0) {
1179 KASSERT(*vpp == NULL, ("leaf should be empty"));
1180 if (error != EJUSTRETURN)
1183 * If creating and at end of pathname, then can consider
1184 * allowing file to be created.
1190 /* ASSERT(dvp == ndp->ni_startdir) */
1191 if (cnp->cn_flags & SAVESTART)
1193 if ((cnp->cn_flags & LOCKPARENT) == 0)
1196 * We return with ni_vp NULL to indicate that the entry
1197 * doesn't currently exist, leaving a pointer to the
1198 * (possibly locked) directory vnode in ndp->ni_dvp.
1206 * Disallow directory write attempts on read-only filesystems.
1209 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
1218 * Set the parent lock/ref state to the requested state.
1220 if ((cnp->cn_flags & LOCKPARENT) == 0 && dvp != dp) {
1225 } else if (!wantparent)
1228 * Check for symbolic link
1230 KASSERT(dp->v_type != VLNK || !(cnp->cn_flags & FOLLOW),
1231 ("relookup: symlink found.\n"));
1233 /* ASSERT(dvp == ndp->ni_startdir) */
1234 if (cnp->cn_flags & SAVESTART)
1237 if ((cnp->cn_flags & LOCKLEAF) == 0)
1247 NDINIT_ALL(struct nameidata *ndp, u_long op, u_long flags, enum uio_seg segflg,
1248 const char *namep, int dirfd, struct vnode *startdir, cap_rights_t *rightsp,
1252 ndp->ni_cnd.cn_nameiop = op;
1253 ndp->ni_cnd.cn_flags = flags;
1254 ndp->ni_segflg = segflg;
1255 ndp->ni_dirp = namep;
1256 ndp->ni_dirfd = dirfd;
1257 ndp->ni_startdir = startdir;
1258 if (rightsp != NULL)
1259 ndp->ni_rightsneeded = *rightsp;
1261 cap_rights_init(&ndp->ni_rightsneeded);
1262 filecaps_init(&ndp->ni_filecaps);
1263 ndp->ni_cnd.cn_thread = td;
1267 * Free data allocated by namei(); see namei(9) for details.
1270 NDFREE(struct nameidata *ndp, const u_int flags)
1278 if (!(flags & NDF_NO_FREE_PNBUF) &&
1279 (ndp->ni_cnd.cn_flags & HASBUF)) {
1280 uma_zfree(namei_zone, ndp->ni_cnd.cn_pnbuf);
1281 ndp->ni_cnd.cn_flags &= ~HASBUF;
1283 if (!(flags & NDF_NO_VP_UNLOCK) &&
1284 (ndp->ni_cnd.cn_flags & LOCKLEAF) && ndp->ni_vp)
1286 if (!(flags & NDF_NO_VP_RELE) && ndp->ni_vp) {
1295 VOP_UNLOCK(ndp->ni_vp, 0);
1296 if (!(flags & NDF_NO_DVP_UNLOCK) &&
1297 (ndp->ni_cnd.cn_flags & LOCKPARENT) &&
1298 ndp->ni_dvp != ndp->ni_vp)
1300 if (!(flags & NDF_NO_DVP_RELE) &&
1301 (ndp->ni_cnd.cn_flags & (LOCKPARENT|WANTPARENT))) {
1310 VOP_UNLOCK(ndp->ni_dvp, 0);
1311 if (!(flags & NDF_NO_STARTDIR_RELE) &&
1312 (ndp->ni_cnd.cn_flags & SAVESTART)) {
1313 vrele(ndp->ni_startdir);
1314 ndp->ni_startdir = NULL;
1319 * Determine if there is a suitable alternate filename under the specified
1320 * prefix for the specified path. If the create flag is set, then the
1321 * alternate prefix will be used so long as the parent directory exists.
1322 * This is used by the various compatibility ABIs so that Linux binaries prefer
1323 * files under /compat/linux for example. The chosen path (whether under
1324 * the prefix or under /) is returned in a kernel malloc'd buffer pointed
1325 * to by pathbuf. The caller is responsible for free'ing the buffer from
1326 * the M_TEMP bucket if one is returned.
1329 kern_alternate_path(struct thread *td, const char *prefix, const char *path,
1330 enum uio_seg pathseg, char **pathbuf, int create, int dirfd)
1332 struct nameidata nd, ndroot;
1333 char *ptr, *buf, *cp;
1337 buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
1340 /* Copy the prefix into the new pathname as a starting point. */
1341 len = strlcpy(buf, prefix, MAXPATHLEN);
1342 if (len >= MAXPATHLEN) {
1347 sz = MAXPATHLEN - len;
1350 /* Append the filename to the prefix. */
1351 if (pathseg == UIO_SYSSPACE)
1352 error = copystr(path, ptr, sz, &len);
1354 error = copyinstr(path, ptr, sz, &len);
1362 /* Only use a prefix with absolute pathnames. */
1368 if (dirfd != AT_FDCWD) {
1370 * We want the original because the "prefix" is
1371 * included in the already opened dirfd.
1373 bcopy(ptr, buf, len);
1378 * We know that there is a / somewhere in this pathname.
1379 * Search backwards for it, to find the file's parent dir
1380 * to see if it exists in the alternate tree. If it does,
1381 * and we want to create a file (cflag is set). We don't
1382 * need to worry about the root comparison in this case.
1386 for (cp = &ptr[len] - 1; *cp != '/'; cp--);
1389 NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_SYSSPACE, buf, td);
1395 NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_SYSSPACE, buf, td);
1402 * We now compare the vnode of the prefix to the one
1403 * vnode asked. If they resolve to be the same, then we
1404 * ignore the match so that the real root gets used.
1405 * This avoids the problem of traversing "../.." to find the
1406 * root directory and never finding it, because "/" resolves
1407 * to the emulation root directory. This is expensive :-(
1409 NDINIT(&ndroot, LOOKUP, FOLLOW, UIO_SYSSPACE, prefix,
1412 /* We shouldn't ever get an error from this namei(). */
1413 error = namei(&ndroot);
1415 if (nd.ni_vp == ndroot.ni_vp)
1418 NDFREE(&ndroot, NDF_ONLY_PNBUF);
1419 vrele(ndroot.ni_vp);
1423 NDFREE(&nd, NDF_ONLY_PNBUF);
1427 /* If there was an error, use the original path name. */
1429 bcopy(ptr, buf, len);