2 * Copyright (c) 2004 The DragonFly Project. All rights reserved.
4 * This code is derived from software contributed to The DragonFly Project
5 * by Matthew Dillon <dillon@backplane.com>
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
17 * 3. Neither the name of The DragonFly Project nor the names of its
18 * contributors may be used to endorse or promote products derived
19 * from this software without specific, prior written permission.
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * $DragonFly: src/sys/kern/vfs_nlookup.c,v 1.25 2008/07/19 04:43:33 dillon Exp $
37 * nlookup() is the 'new' namei interface. Rather then return directory and
38 * leaf vnodes (in various lock states) the new interface instead deals in
39 * namecache records. Namecache records may represent both a positive or
40 * a negative hit. The namespace is locked via the namecache record instead
41 * of via the vnode, and only the leaf namecache record (representing the
42 * filename) needs to be locked.
44 * This greatly improves filesystem parallelism and is a huge simplification
45 * of the API verses the old vnode locking / namei scheme.
47 * Filesystems must actively control the caching aspects of the namecache,
48 * and since namecache pointers are used as handles they are non-optional
49 * even for filesystems which do not generally wish to cache things. It is
50 * intended that a separate cache coherency API will be constructed to handle
54 #include "opt_ktrace.h"
56 #include <sys/param.h>
57 #include <sys/systm.h>
58 #include <sys/kernel.h>
59 #include <sys/vnode.h>
60 #include <sys/mount.h>
61 #include <sys/filedesc.h>
63 #include <sys/namei.h>
64 #include <sys/nlookup.h>
65 #include <sys/malloc.h>
67 #include <sys/objcache.h>
70 #include <sys/ktrace.h>
73 static int naccess_va(struct vattr *va, int vmode, struct ucred *cred);
76 * Initialize a nlookup() structure, early error return for copyin faults
77 * or a degenerate empty string (which is not allowed).
79 * The first process proc0's credentials are used if the calling thread
80 * is not associated with a process context.
83 nlookup_init(struct nlookupdata *nd,
84 const char *path, enum uio_seg seg, int flags)
95 * note: the pathlen set by copy*str() includes the terminating \0.
97 bzero(nd, sizeof(struct nlookupdata));
98 nd->nl_path = objcache_get(namei_oc, M_WAITOK);
99 nd->nl_flags |= NLC_HASBUF;
100 if (seg == UIO_SYSSPACE)
101 error = copystr(path, nd->nl_path, MAXPATHLEN, &pathlen);
103 error = copyinstr(path, nd->nl_path, MAXPATHLEN, &pathlen);
106 * Don't allow empty pathnames.
107 * POSIX.1 requirement: "" is not a vaild file name.
109 if (error == 0 && pathlen <= 1)
114 cache_copy(&p->p_fd->fd_ncdir, &nd->nl_nch);
115 cache_copy(&p->p_fd->fd_nrdir, &nd->nl_rootnch);
116 if (p->p_fd->fd_njdir.ncp)
117 cache_copy(&p->p_fd->fd_njdir, &nd->nl_jailnch);
118 nd->nl_cred = crhold(p->p_ucred);
120 cache_copy(&rootnch, &nd->nl_nch);
121 cache_copy(&nd->nl_nch, &nd->nl_rootnch);
122 cache_copy(&nd->nl_nch, &nd->nl_jailnch);
123 nd->nl_cred = crhold(proc0.p_ucred);
126 nd->nl_flags |= flags;
134 * This works similarly to nlookup_init() but does not assume a process
135 * context. rootnch is always chosen for the root directory and the cred
136 * and starting directory are supplied in arguments.
139 nlookup_init_raw(struct nlookupdata *nd,
140 const char *path, enum uio_seg seg, int flags,
141 struct ucred *cred, struct nchandle *ncstart)
149 bzero(nd, sizeof(struct nlookupdata));
150 nd->nl_path = objcache_get(namei_oc, M_WAITOK);
151 nd->nl_flags |= NLC_HASBUF;
152 if (seg == UIO_SYSSPACE)
153 error = copystr(path, nd->nl_path, MAXPATHLEN, &pathlen);
155 error = copyinstr(path, nd->nl_path, MAXPATHLEN, &pathlen);
158 * Don't allow empty pathnames.
159 * POSIX.1 requirement: "" is not a vaild file name.
161 if (error == 0 && pathlen <= 1)
165 cache_copy(ncstart, &nd->nl_nch);
166 cache_copy(&rootnch, &nd->nl_rootnch);
167 cache_copy(&rootnch, &nd->nl_jailnch);
168 nd->nl_cred = crhold(cred);
170 nd->nl_flags |= flags;
178 * Set a different credential; this credential will be used by future
179 * operations performed on nd.nl_open_vp and nlookupdata structure.
182 nlookup_set_cred(struct nlookupdata *nd, struct ucred *cred)
184 KKASSERT(nd->nl_cred != NULL);
186 if (nd->nl_cred != cred) {
194 * Cleanup a nlookupdata structure after we are through with it. This may
195 * be called on any nlookupdata structure initialized with nlookup_init().
196 * Calling nlookup_done() is mandatory in all cases except where nlookup_init()
197 * returns an error, even if as a consumer you believe you have taken all
198 * dynamic elements out of the nlookupdata structure.
201 nlookup_done(struct nlookupdata *nd)
203 if (nd->nl_nch.ncp) {
204 if (nd->nl_flags & NLC_NCPISLOCKED) {
205 nd->nl_flags &= ~NLC_NCPISLOCKED;
206 cache_unlock(&nd->nl_nch);
208 cache_drop(&nd->nl_nch);
210 if (nd->nl_rootnch.ncp)
211 cache_drop(&nd->nl_rootnch);
212 if (nd->nl_jailnch.ncp)
213 cache_drop(&nd->nl_jailnch);
214 if ((nd->nl_flags & NLC_HASBUF) && nd->nl_path) {
215 objcache_put(namei_oc, nd->nl_path);
222 if (nd->nl_open_vp) {
223 if (nd->nl_flags & NLC_LOCKVP) {
224 vn_unlock(nd->nl_open_vp);
225 nd->nl_flags &= ~NLC_LOCKVP;
227 vn_close(nd->nl_open_vp, nd->nl_vp_fmode);
228 nd->nl_open_vp = NULL;
234 nd->nl_flags = 0; /* clear remaining flags (just clear everything) */
238 nlookup_zero(struct nlookupdata *nd)
240 bzero(nd, sizeof(struct nlookupdata));
244 * Simple all-in-one nlookup. Returns a locked namecache structure or NULL
245 * if an error occured.
247 * Note that the returned ncp is not checked for permissions, though VEXEC
248 * is checked on the directory path leading up to the result. The caller
249 * must call naccess() to check the permissions of the returned leaf.
252 nlookup_simple(const char *str, enum uio_seg seg,
253 int niflags, int *error)
255 struct nlookupdata nd;
258 *error = nlookup_init(&nd, str, seg, niflags);
260 if ((*error = nlookup(&nd)) == 0) {
261 nch = nd.nl_nch; /* keep hold ref from structure */
262 cache_zero(&nd.nl_nch); /* and NULL out */
274 * Do a generic nlookup. Note that the passed nd is not nlookup_done()'d
275 * on return, even if an error occurs. If no error occurs the returned
276 * nl_nch is always referenced and locked, otherwise it may or may not be.
278 * Intermediate directory elements, including the current directory, require
279 * execute (search) permission. nlookup does not examine the access
280 * permissions on the returned element.
282 * If NLC_CREATE or NLC_DELETE is set the last directory must allow node
283 * creation (VCREATE/VDELETE), and an error code of 0 will be returned for
284 * a non-existant target. Otherwise a non-existant target will cause
285 * ENOENT to be returned.
287 * If NLC_REFDVP is set nd->nl_dvp will be set to the directory vnode
288 * of the returned entry. The vnode will be referenced, but not locked,
289 * and will be released by nlookup_done() along with everything else.
292 nlookup(struct nlookupdata *nd)
294 struct nlcomponent nlc;
304 if (KTRPOINT(nd->nl_td, KTR_NAMEI))
305 ktrnamei(nd->nl_td->td_lwp, nd->nl_path);
307 bzero(&nlc, sizeof(nlc));
310 * Setup for the loop. The current working namecache element must
311 * be in a refd + unlocked state. This typically the case on entry except
312 * when stringing nlookup()'s along in a chain, since nlookup() always
313 * returns nl_nch in a locked state.
316 if (nd->nl_flags & NLC_NCPISLOCKED) {
317 nd->nl_flags &= ~NLC_NCPISLOCKED;
318 cache_unlock(&nd->nl_nch);
327 * Loop on the path components. At the top of the loop nd->nl_nch
328 * is ref'd and unlocked and represents our current position.
332 * Check if the root directory should replace the current
333 * directory. This is done at the start of a translation
334 * or after a symbolic link has been found. In other cases
335 * ptr will never be pointing at a '/'.
340 } while (*ptr == '/');
341 cache_copy(&nd->nl_rootnch, &nch);
342 cache_drop(&nd->nl_nch);
346 * Fast-track termination. There is no parent directory of
347 * the root in the same mount from the point of view of
348 * the caller so return EPERM if NLC_REFDVP is specified.
349 * e.g. 'rmdir /' is not allowed.
352 if (nd->nl_flags & NLC_REFDVP) {
355 cache_lock(&nd->nl_nch);
356 nd->nl_flags |= NLC_NCPISLOCKED;
365 * Check directory search permissions.
367 if ((error = naccess(&nd->nl_nch, VEXEC, nd->nl_cred, NULL)) != 0)
371 * Extract the path component
373 nlc.nlc_nameptr = ptr;
374 while (*ptr && *ptr != '/')
376 nlc.nlc_namelen = ptr - nlc.nlc_nameptr;
379 * Lookup the path component in the cache, creating an unresolved
380 * entry if necessary. We have to handle "." and ".." as special
383 * When handling ".." we have to detect a traversal back through a
384 * mount point. If we are at the root, ".." just returns the root.
386 * This subsection returns a locked, refd 'nch' unless it errors out.
387 * The namecache topology is not allowed to be disconnected, so
388 * encountering a NULL parent will generate EINVAL. This typically
389 * occurs when a directory is removed out from under a process.
391 * If NLC_DELETE is set neither '.' or '..' can be the last component
394 if (nlc.nlc_namelen == 1 && nlc.nlc_nameptr[0] == '.') {
395 cache_get(&nd->nl_nch, &nch);
397 } else if (nlc.nlc_namelen == 2 &&
398 nlc.nlc_nameptr[0] == '.' && nlc.nlc_nameptr[1] == '.') {
399 if (nd->nl_nch.mount == nd->nl_rootnch.mount &&
400 nd->nl_nch.ncp == nd->nl_rootnch.ncp
403 * ".." at the root returns the root
405 cache_get(&nd->nl_nch, &nch);
408 * Locate the parent ncp. If we are at the root of a
409 * filesystem mount we have to skip to the mounted-on
410 * point in the underlying filesystem.
413 while (nch.ncp == nch.mount->mnt_ncmountpt.ncp)
414 nch = nch.mount->mnt_ncmounton;
415 nch.ncp = nch.ncp->nc_parent;
416 KKASSERT(nch.ncp != NULL);
417 cache_get(&nch, &nch);
421 nch = cache_nlookup(&nd->nl_nch, &nlc);
422 while ((error = cache_resolve(&nch, nd->nl_cred)) == EAGAIN) {
423 kprintf("[diagnostic] nlookup: relookup %*.*s\n",
424 nch.ncp->nc_nlen, nch.ncp->nc_nlen, nch.ncp->nc_name);
426 nch = cache_nlookup(&nd->nl_nch, &nlc);
431 * [end of subsection] ncp is locked and ref'd. nd->nl_nch is ref'd
435 * Resolve the namespace if necessary. The ncp returned by
436 * cache_nlookup() is referenced and locked.
438 * XXX neither '.' nor '..' should return EAGAIN since they were
439 * previously resolved and thus cannot be newly created ncp's.
441 if (nch.ncp->nc_flag & NCF_UNRESOLVED) {
442 error = cache_resolve(&nch, nd->nl_cred);
443 KKASSERT(error != EAGAIN);
445 error = nch.ncp->nc_error;
449 * Early completion. ENOENT is not an error if this is the last
450 * component and NLC_CREATE was requested. Note that ncp->nc_error
451 * is left as ENOENT in that case, which we check later on.
453 * Also handle invalid '.' or '..' components terminating a path
454 * during removal. The standard requires this and pax pretty
455 * stupidly depends on it.
457 for (xptr = ptr; *xptr == '/'; ++xptr)
460 if (error == ENOENT && (nd->nl_flags & NLC_CREATE)) {
461 if (nd->nl_flags & NLC_NFS_RDONLY)
464 error = naccess(&nch, VCREATE, nd->nl_cred, NULL);
466 if (error == 0 && wasdotordotdot && (nd->nl_flags & NLC_DELETE))
471 * Early completion on error.
479 * If the element is a symlink and it is either not the last
480 * element or it is the last element and we are allowed to
481 * follow symlinks, resolve the symlink.
483 if ((nch.ncp->nc_flag & NCF_ISSYMLINK) &&
484 (*ptr || (nd->nl_flags & NLC_FOLLOW))
486 if (nd->nl_loopcnt++ >= MAXSYMLINKS) {
491 error = nreadsymlink(nd, &nch, &nlc);
497 * Concatenate trailing path elements onto the returned symlink.
498 * Note that if the path component (ptr) is not exhausted, it
499 * will being with a '/', so we do not have to add another one.
501 * The symlink may not be empty.
504 if (nlc.nlc_namelen == 0 || nlc.nlc_namelen + len >= MAXPATHLEN) {
505 error = nlc.nlc_namelen ? ENAMETOOLONG : ENOENT;
506 objcache_put(namei_oc, nlc.nlc_nameptr);
509 bcopy(ptr, nlc.nlc_nameptr + nlc.nlc_namelen, len + 1);
510 if (nd->nl_flags & NLC_HASBUF)
511 objcache_put(namei_oc, nd->nl_path);
512 nd->nl_path = nlc.nlc_nameptr;
513 nd->nl_flags |= NLC_HASBUF;
517 * Go back up to the top to resolve any initial '/'s in the
524 * If the element is a directory and we are crossing a mount point,
527 while ((nch.ncp->nc_flag & NCF_ISMOUNTPT) &&
528 (nd->nl_flags & NLC_NOCROSSMOUNT) == 0 &&
529 (mp = cache_findmount(&nch)) != NULL
534 cache_get(&mp->mnt_ncmountpt, &nch);
536 if (nch.ncp->nc_flag & NCF_UNRESOLVED) {
537 while (vfs_busy(mp, 0))
539 error = VFS_ROOT(mp, &tdp);
543 cache_setvp(&nch, tdp);
553 * Skip any slashes to get to the next element. If there
554 * are any slashes at all the current element must be a
555 * directory or, in the create case, intended to become a directory.
556 * If it isn't we break without incrementing ptr and fall through
557 * to the failure case below.
559 while (*ptr == '/') {
560 if ((nch.ncp->nc_flag & NCF_ISDIR) == 0 &&
561 !(nd->nl_flags & NLC_WILLBEDIR)
569 * Continuation case: additional elements and the current
570 * element is a directory.
572 if (*ptr && (nch.ncp->nc_flag & NCF_ISDIR)) {
573 cache_drop(&nd->nl_nch);
580 * Failure case: additional elements and the current element
590 * Successful lookup of last element.
592 * Check directory permissions if a deletion is specified.
594 if (*ptr == 0 && (nd->nl_flags & NLC_DELETE)) {
595 if ((error = naccess(&nch, VDELETE, nd->nl_cred, NULL)) != 0) {
602 * Termination: no more elements. If NLC_CREATE was set the
603 * ncp may represent a negative hit (ncp->nc_error will be ENOENT),
604 * but we still return an error code of 0.
606 * If NLC_REFDVP is set acquire a referenced parent dvp.
608 if (nd->nl_flags & NLC_REFDVP) {
609 error = cache_vref(&nd->nl_nch, nd->nl_cred, &nd->nl_dvp);
611 kprintf("NLC_REFDVP: Cannot ref dvp of %p\n", nch.ncp);
616 cache_drop(&nd->nl_nch);
618 nd->nl_flags |= NLC_NCPISLOCKED;
626 * Resolve a mount point's glue ncp. This ncp connects creates the illusion
627 * of continuity in the namecache tree by connecting the ncp related to the
628 * vnode under the mount to the ncp related to the mount's root vnode.
630 * If no error occured a locked, ref'd ncp is stored in *ncpp.
633 nlookup_mp(struct mount *mp, struct nchandle *nch)
639 cache_get(&mp->mnt_ncmountpt, nch);
640 if (nch->ncp->nc_flag & NCF_UNRESOLVED) {
641 while (vfs_busy(mp, 0))
643 error = VFS_ROOT(mp, &vp);
648 cache_setvp(nch, vp);
656 * Read the contents of a symlink, allocate a path buffer out of the
657 * namei_oc and initialize the supplied nlcomponent with the result.
659 * If an error occurs no buffer will be allocated or returned in the nlc.
662 nreadsymlink(struct nlookupdata *nd, struct nchandle *nch,
663 struct nlcomponent *nlc)
672 nlc->nlc_nameptr = NULL;
673 nlc->nlc_namelen = 0;
674 if (nch->ncp->nc_vp == NULL)
676 if ((error = cache_vget(nch, nd->nl_cred, LK_SHARED, &vp)) != 0)
678 cp = objcache_get(namei_oc, M_WAITOK);
680 aiov.iov_len = MAXPATHLEN;
681 auio.uio_iov = &aiov;
684 auio.uio_rw = UIO_READ;
685 auio.uio_segflg = UIO_SYSSPACE;
686 auio.uio_td = nd->nl_td;
687 auio.uio_resid = MAXPATHLEN - 1;
688 error = VOP_READLINK(vp, &auio, nd->nl_cred);
691 linklen = MAXPATHLEN - 1 - auio.uio_resid;
693 linklen = varsymreplace(cp, linklen, MAXPATHLEN - 1);
695 error = ENAMETOOLONG;
700 nlc->nlc_nameptr = cp;
701 nlc->nlc_namelen = linklen;
705 objcache_put(namei_oc, cp);
711 * Check access [XXX cache vattr!] [XXX quota]
713 * Generally check the V* access bits from sys/vnode.h. All specified bits
714 * must pass for this function to return 0.
716 * If VCREATE is specified and the target ncp represents a non-existant
717 * file or dir, or if VDELETE is specified and the target exists, the parent
718 * directory is checked for VWRITE. If VEXCL is specified and the target
719 * ncp represents a positive hit, an error is returned.
721 * If VCREATE is not specified and the target does not exist (negative hit),
722 * ENOENT is returned. Note that nlookup() does not (and should not) return
723 * ENOENT for non-existant leafs.
725 * If VDELETE is specified we also do sticky-bit tests on the parent
728 * The passed ncp may or may not be locked. The caller should use a
729 * locked ncp on leaf lookups, especially for VCREATE, VDELETE, and VEXCL
733 naccess(struct nchandle *nch, int vmode, struct ucred *cred, int *stickyp)
741 if (nch->ncp->nc_flag & NCF_UNRESOLVED) {
743 cache_resolve(nch, cred);
746 error = nch->ncp->nc_error;
749 if (vmode & (VDELETE|VCREATE|VEXCL)) {
750 if (((vmode & VCREATE) && nch->ncp->nc_vp == NULL) ||
751 ((vmode & VDELETE) && nch->ncp->nc_vp != NULL)
753 if ((par.ncp = nch->ncp->nc_parent) == NULL) {
757 par.mount = nch->mount;
759 error = naccess(&par, VWRITE, cred, &sticky);
760 if ((vmode & VDELETE) && sticky)
765 if ((vmode & VEXCL) && nch->ncp->nc_vp != NULL)
769 error = cache_vget(nch, cred, LK_SHARED, &vp);
770 if (error == ENOENT) {
773 } else if (error == 0) {
774 /* XXX cache the va in the namecache or in the vnode */
775 if ((error = VOP_GETATTR(vp, &va)) == 0) {
776 if ((vmode & VWRITE) && vp->v_mount) {
777 if (vp->v_mount->mnt_flag & MNT_RDONLY)
785 * Set the returned (*stickyp) if VSVTX is set and the uid
786 * is not the owner of the directory. The caller uses this
787 * disallow deletions of files not owned by the user if the
788 * user also does not own the directory and the sticky bit
789 * is set on the directory. Weird, I know.
791 if (stickyp && va.va_uid != cred->cr_uid)
792 *stickyp = (va.va_mode & VSVTX);
795 * Process general access.
797 error = naccess_va(&va, vmode, cred);
805 * Check the requested access against the given vattr using cred.
809 naccess_va(struct vattr *va, int vmode, struct ucred *cred)
814 * Test the immutable bit for files, directories, and softlinks.
816 if (vmode & (VWRITE|VDELETE)) {
817 if (va->va_type == VDIR || va->va_type == VLNK || va->va_type == VREG) {
818 if (va->va_flags & IMMUTABLE)
824 * root gets universal access
826 if (cred->cr_uid == 0)
832 * If VOWN is set the owner of the file is allowed no matter when
833 * the owner-mode bits say (utimes).
835 if (cred->cr_uid == va->va_uid) {
836 if ((vmode & VOWN) == 0) {
838 if ((vmode & va->va_mode) != vmode)
845 * If VSVTX is set only the owner may access the file. This bit is
846 * typically set for VDELETE checks on files in sticky directories
847 * when the user does not own the directory. Note that other V bits
848 * are not typically set (for deletions we usually just care about
849 * the directory permissions, not the file permissions).
851 * The effect on VDELETE checks is thus to not allow the deletion
852 * of the file, and otherwise allow it.
862 for (i = 0; i < cred->cr_ngroups; ++i) {
863 if (va->va_gid == cred->cr_groups[i]) {
864 if ((vmode & va->va_mode) != vmode)
874 if ((vmode & va->va_mode) != vmode)