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>
74 * Initialize a nlookup() structure, early error return for copyin faults
75 * or a degenerate empty string (which is not allowed).
77 * The first process proc0's credentials are used if the calling thread
78 * is not associated with a process context.
81 nlookup_init(struct nlookupdata *nd,
82 const char *path, enum uio_seg seg, int flags)
93 * note: the pathlen set by copy*str() includes the terminating \0.
95 bzero(nd, sizeof(struct nlookupdata));
96 nd->nl_path = objcache_get(namei_oc, M_WAITOK);
97 nd->nl_flags |= NLC_HASBUF;
98 if (seg == UIO_SYSSPACE)
99 error = copystr(path, nd->nl_path, MAXPATHLEN, &pathlen);
101 error = copyinstr(path, nd->nl_path, MAXPATHLEN, &pathlen);
104 * Don't allow empty pathnames.
105 * POSIX.1 requirement: "" is not a vaild file name.
107 if (error == 0 && pathlen <= 1)
112 cache_copy(&p->p_fd->fd_ncdir, &nd->nl_nch);
113 cache_copy(&p->p_fd->fd_nrdir, &nd->nl_rootnch);
114 if (p->p_fd->fd_njdir.ncp)
115 cache_copy(&p->p_fd->fd_njdir, &nd->nl_jailnch);
116 nd->nl_cred = crhold(p->p_ucred);
118 cache_copy(&rootnch, &nd->nl_nch);
119 cache_copy(&nd->nl_nch, &nd->nl_rootnch);
120 cache_copy(&nd->nl_nch, &nd->nl_jailnch);
121 nd->nl_cred = crhold(proc0.p_ucred);
124 nd->nl_flags |= flags;
132 * This works similarly to nlookup_init() but does not assume a process
133 * context. rootnch is always chosen for the root directory and the cred
134 * and starting directory are supplied in arguments.
137 nlookup_init_raw(struct nlookupdata *nd,
138 const char *path, enum uio_seg seg, int flags,
139 struct ucred *cred, struct nchandle *ncstart)
147 bzero(nd, sizeof(struct nlookupdata));
148 nd->nl_path = objcache_get(namei_oc, M_WAITOK);
149 nd->nl_flags |= NLC_HASBUF;
150 if (seg == UIO_SYSSPACE)
151 error = copystr(path, nd->nl_path, MAXPATHLEN, &pathlen);
153 error = copyinstr(path, nd->nl_path, MAXPATHLEN, &pathlen);
156 * Don't allow empty pathnames.
157 * POSIX.1 requirement: "" is not a vaild file name.
159 if (error == 0 && pathlen <= 1)
163 cache_copy(ncstart, &nd->nl_nch);
164 cache_copy(&rootnch, &nd->nl_rootnch);
165 cache_copy(&rootnch, &nd->nl_jailnch);
166 nd->nl_cred = crhold(cred);
168 nd->nl_flags |= flags;
176 * Set a different credential; this credential will be used by future
177 * operations performed on nd.nl_open_vp and nlookupdata structure.
180 nlookup_set_cred(struct nlookupdata *nd, struct ucred *cred)
182 KKASSERT(nd->nl_cred != NULL);
184 if (nd->nl_cred != cred) {
192 * Cleanup a nlookupdata structure after we are through with it. This may
193 * be called on any nlookupdata structure initialized with nlookup_init().
194 * Calling nlookup_done() is mandatory in all cases except where nlookup_init()
195 * returns an error, even if as a consumer you believe you have taken all
196 * dynamic elements out of the nlookupdata structure.
199 nlookup_done(struct nlookupdata *nd)
201 if (nd->nl_nch.ncp) {
202 if (nd->nl_flags & NLC_NCPISLOCKED) {
203 nd->nl_flags &= ~NLC_NCPISLOCKED;
204 cache_unlock(&nd->nl_nch);
206 cache_drop(&nd->nl_nch);
208 if (nd->nl_rootnch.ncp)
209 cache_drop(&nd->nl_rootnch);
210 if (nd->nl_jailnch.ncp)
211 cache_drop(&nd->nl_jailnch);
212 if ((nd->nl_flags & NLC_HASBUF) && nd->nl_path) {
213 objcache_put(namei_oc, nd->nl_path);
220 if (nd->nl_open_vp) {
221 if (nd->nl_flags & NLC_LOCKVP) {
222 vn_unlock(nd->nl_open_vp);
223 nd->nl_flags &= ~NLC_LOCKVP;
225 vn_close(nd->nl_open_vp, nd->nl_vp_fmode);
226 nd->nl_open_vp = NULL;
232 nd->nl_flags = 0; /* clear remaining flags (just clear everything) */
236 nlookup_zero(struct nlookupdata *nd)
238 bzero(nd, sizeof(struct nlookupdata));
242 * Simple all-in-one nlookup. Returns a locked namecache structure or NULL
243 * if an error occured.
245 * Note that the returned ncp is not checked for permissions, though VEXEC
246 * is checked on the directory path leading up to the result. The caller
247 * must call naccess() to check the permissions of the returned leaf.
250 nlookup_simple(const char *str, enum uio_seg seg,
251 int niflags, int *error)
253 struct nlookupdata nd;
256 *error = nlookup_init(&nd, str, seg, niflags);
258 if ((*error = nlookup(&nd)) == 0) {
259 nch = nd.nl_nch; /* keep hold ref from structure */
260 cache_zero(&nd.nl_nch); /* and NULL out */
272 * Do a generic nlookup. Note that the passed nd is not nlookup_done()'d
273 * on return, even if an error occurs. If no error occurs the returned
274 * nl_nch is always referenced and locked, otherwise it may or may not be.
276 * Intermediate directory elements, including the current directory, require
277 * execute (search) permission. nlookup does not examine the access
278 * permissions on the returned element.
280 * If NLC_CREATE or NLC_DELETE is set the last directory must allow node
281 * creation (VCREATE/VDELETE), and an error code of 0 will be returned for
282 * a non-existant target. Otherwise a non-existant target will cause
283 * ENOENT to be returned.
285 * If NLC_REFDVP is set nd->nl_dvp will be set to the directory vnode
286 * of the returned entry. The vnode will be referenced, but not locked,
287 * and will be released by nlookup_done() along with everything else.
290 nlookup(struct nlookupdata *nd)
292 struct nlcomponent nlc;
302 if (KTRPOINT(nd->nl_td, KTR_NAMEI))
303 ktrnamei(nd->nl_td->td_lwp, nd->nl_path);
305 bzero(&nlc, sizeof(nlc));
308 * Setup for the loop. The current working namecache element must
309 * be in a refd + unlocked state. This typically the case on entry except
310 * when stringing nlookup()'s along in a chain, since nlookup() always
311 * returns nl_nch in a locked state.
314 if (nd->nl_flags & NLC_NCPISLOCKED) {
315 nd->nl_flags &= ~NLC_NCPISLOCKED;
316 cache_unlock(&nd->nl_nch);
325 * Loop on the path components. At the top of the loop nd->nl_nch
326 * is ref'd and unlocked and represents our current position.
330 * Check if the root directory should replace the current
331 * directory. This is done at the start of a translation
332 * or after a symbolic link has been found. In other cases
333 * ptr will never be pointing at a '/'.
338 } while (*ptr == '/');
339 cache_copy(&nd->nl_rootnch, &nch);
340 cache_drop(&nd->nl_nch);
344 * Fast-track termination. There is no parent directory of
345 * the root in the same mount from the point of view of
346 * the caller so return EPERM if NLC_REFDVP is specified.
347 * e.g. 'rmdir /' is not allowed.
350 if (nd->nl_flags & NLC_REFDVP) {
353 cache_lock(&nd->nl_nch);
354 nd->nl_flags |= NLC_NCPISLOCKED;
363 * Check directory search permissions.
365 if ((error = naccess(&nd->nl_nch, VEXEC, nd->nl_cred)) != 0)
369 * Extract the path component
371 nlc.nlc_nameptr = ptr;
372 while (*ptr && *ptr != '/')
374 nlc.nlc_namelen = ptr - nlc.nlc_nameptr;
377 * Lookup the path component in the cache, creating an unresolved
378 * entry if necessary. We have to handle "." and ".." as special
381 * When handling ".." we have to detect a traversal back through a
382 * mount point. If we are at the root, ".." just returns the root.
384 * This subsection returns a locked, refd 'nch' unless it errors out.
385 * The namecache topology is not allowed to be disconnected, so
386 * encountering a NULL parent will generate EINVAL. This typically
387 * occurs when a directory is removed out from under a process.
389 * If NLC_DELETE is set neither '.' or '..' can be the last component
392 if (nlc.nlc_namelen == 1 && nlc.nlc_nameptr[0] == '.') {
393 cache_get(&nd->nl_nch, &nch);
395 } else if (nlc.nlc_namelen == 2 &&
396 nlc.nlc_nameptr[0] == '.' && nlc.nlc_nameptr[1] == '.') {
397 if (nd->nl_nch.mount == nd->nl_rootnch.mount &&
398 nd->nl_nch.ncp == nd->nl_rootnch.ncp
401 * ".." at the root returns the root
403 cache_get(&nd->nl_nch, &nch);
406 * Locate the parent ncp. If we are at the root of a
407 * filesystem mount we have to skip to the mounted-on
408 * point in the underlying filesystem.
411 while (nch.ncp == nch.mount->mnt_ncmountpt.ncp)
412 nch = nch.mount->mnt_ncmounton;
413 nch.ncp = nch.ncp->nc_parent;
414 KKASSERT(nch.ncp != NULL);
415 cache_get(&nch, &nch);
419 nch = cache_nlookup(&nd->nl_nch, &nlc);
420 while ((error = cache_resolve(&nch, nd->nl_cred)) == EAGAIN) {
421 kprintf("[diagnostic] nlookup: relookup %*.*s\n",
422 nch.ncp->nc_nlen, nch.ncp->nc_nlen, nch.ncp->nc_name);
424 nch = cache_nlookup(&nd->nl_nch, &nlc);
429 * [end of subsection] ncp is locked and ref'd. nd->nl_nch is ref'd
433 * Resolve the namespace if necessary. The ncp returned by
434 * cache_nlookup() is referenced and locked.
436 * XXX neither '.' nor '..' should return EAGAIN since they were
437 * previously resolved and thus cannot be newly created ncp's.
439 if (nch.ncp->nc_flag & NCF_UNRESOLVED) {
440 error = cache_resolve(&nch, nd->nl_cred);
441 KKASSERT(error != EAGAIN);
443 error = nch.ncp->nc_error;
447 * Early completion. ENOENT is not an error if this is the last
448 * component and NLC_CREATE was requested. Note that ncp->nc_error
449 * is left as ENOENT in that case, which we check later on.
451 * Also handle invalid '.' or '..' components terminating a path
452 * during removal. The standard requires this and pax pretty
453 * stupidly depends on it.
455 for (xptr = ptr; *xptr == '/'; ++xptr)
458 if (error == ENOENT && (nd->nl_flags & NLC_CREATE)) {
459 if (nd->nl_flags & NLC_NFS_RDONLY)
462 error = naccess(&nch, VCREATE, nd->nl_cred);
464 if (error == 0 && wasdotordotdot && (nd->nl_flags & NLC_DELETE))
469 * Early completion on error.
477 * If the element is a symlink and it is either not the last
478 * element or it is the last element and we are allowed to
479 * follow symlinks, resolve the symlink.
481 if ((nch.ncp->nc_flag & NCF_ISSYMLINK) &&
482 (*ptr || (nd->nl_flags & NLC_FOLLOW))
484 if (nd->nl_loopcnt++ >= MAXSYMLINKS) {
489 error = nreadsymlink(nd, &nch, &nlc);
495 * Concatenate trailing path elements onto the returned symlink.
496 * Note that if the path component (ptr) is not exhausted, it
497 * will being with a '/', so we do not have to add another one.
499 * The symlink may not be empty.
502 if (nlc.nlc_namelen == 0 || nlc.nlc_namelen + len >= MAXPATHLEN) {
503 error = nlc.nlc_namelen ? ENAMETOOLONG : ENOENT;
504 objcache_put(namei_oc, nlc.nlc_nameptr);
507 bcopy(ptr, nlc.nlc_nameptr + nlc.nlc_namelen, len + 1);
508 if (nd->nl_flags & NLC_HASBUF)
509 objcache_put(namei_oc, nd->nl_path);
510 nd->nl_path = nlc.nlc_nameptr;
511 nd->nl_flags |= NLC_HASBUF;
515 * Go back up to the top to resolve any initial '/'s in the
522 * If the element is a directory and we are crossing a mount point,
525 while ((nch.ncp->nc_flag & NCF_ISMOUNTPT) &&
526 (nd->nl_flags & NLC_NOCROSSMOUNT) == 0 &&
527 (mp = cache_findmount(&nch)) != NULL
532 cache_get(&mp->mnt_ncmountpt, &nch);
534 if (nch.ncp->nc_flag & NCF_UNRESOLVED) {
535 while (vfs_busy(mp, 0))
537 error = VFS_ROOT(mp, &tdp);
541 cache_setvp(&nch, tdp);
551 * Skip any slashes to get to the next element. If there
552 * are any slashes at all the current element must be a
553 * directory or, in the create case, intended to become a directory.
554 * If it isn't we break without incrementing ptr and fall through
555 * to the failure case below.
557 while (*ptr == '/') {
558 if ((nch.ncp->nc_flag & NCF_ISDIR) == 0 &&
559 !(nd->nl_flags & NLC_WILLBEDIR)
567 * Continuation case: additional elements and the current
568 * element is a directory.
570 if (*ptr && (nch.ncp->nc_flag & NCF_ISDIR)) {
571 cache_drop(&nd->nl_nch);
578 * Failure case: additional elements and the current element
588 * Successful lookup of last element.
590 * Check directory permissions if a deletion is specified.
592 if (*ptr == 0 && (nd->nl_flags & NLC_DELETE)) {
593 if ((error = naccess(&nch, VDELETE, nd->nl_cred)) != 0) {
600 * Termination: no more elements. If NLC_CREATE was set the
601 * ncp may represent a negative hit (ncp->nc_error will be ENOENT),
602 * but we still return an error code of 0.
604 * If NLC_REFDVP is set acquire a referenced parent dvp.
606 if (nd->nl_flags & NLC_REFDVP) {
607 error = cache_vref(&nd->nl_nch, nd->nl_cred, &nd->nl_dvp);
609 kprintf("NLC_REFDVP: Cannot ref dvp of %p\n", nch.ncp);
614 cache_drop(&nd->nl_nch);
616 nd->nl_flags |= NLC_NCPISLOCKED;
624 * Resolve a mount point's glue ncp. This ncp connects creates the illusion
625 * of continuity in the namecache tree by connecting the ncp related to the
626 * vnode under the mount to the ncp related to the mount's root vnode.
628 * If no error occured a locked, ref'd ncp is stored in *ncpp.
631 nlookup_mp(struct mount *mp, struct nchandle *nch)
637 cache_get(&mp->mnt_ncmountpt, nch);
638 if (nch->ncp->nc_flag & NCF_UNRESOLVED) {
639 while (vfs_busy(mp, 0))
641 error = VFS_ROOT(mp, &vp);
646 cache_setvp(nch, vp);
654 * Read the contents of a symlink, allocate a path buffer out of the
655 * namei_oc and initialize the supplied nlcomponent with the result.
657 * If an error occurs no buffer will be allocated or returned in the nlc.
660 nreadsymlink(struct nlookupdata *nd, struct nchandle *nch,
661 struct nlcomponent *nlc)
670 nlc->nlc_nameptr = NULL;
671 nlc->nlc_namelen = 0;
672 if (nch->ncp->nc_vp == NULL)
674 if ((error = cache_vget(nch, nd->nl_cred, LK_SHARED, &vp)) != 0)
676 cp = objcache_get(namei_oc, M_WAITOK);
678 aiov.iov_len = MAXPATHLEN;
679 auio.uio_iov = &aiov;
682 auio.uio_rw = UIO_READ;
683 auio.uio_segflg = UIO_SYSSPACE;
684 auio.uio_td = nd->nl_td;
685 auio.uio_resid = MAXPATHLEN - 1;
686 error = VOP_READLINK(vp, &auio, nd->nl_cred);
689 linklen = MAXPATHLEN - 1 - auio.uio_resid;
691 linklen = varsymreplace(cp, linklen, MAXPATHLEN - 1);
693 error = ENAMETOOLONG;
698 nlc->nlc_nameptr = cp;
699 nlc->nlc_namelen = linklen;
703 objcache_put(namei_oc, cp);
709 * Check access [XXX cache vattr!] [XXX quota]
711 * Generally check the V* access bits from sys/vnode.h. All specified bits
712 * must pass for this function to return 0.
714 * If VCREATE is specified and the target ncp represents a non-existant
715 * file or dir, or if VDELETE is specified and the target exists, the parent
716 * directory is checked for VWRITE. If VEXCL is specified and the target
717 * ncp represents a positive hit, an error is returned.
719 * If VCREATE is not specified and the target does not exist (negative hit),
720 * ENOENT is returned. Note that nlookup() does not (and should not) return
721 * ENOENT for non-existant leafs.
723 * The passed ncp may or may not be locked. The caller should use a
724 * locked ncp on leaf lookups, especially for VCREATE, VDELETE, and VEXCL
728 naccess(struct nchandle *nch, int vmode, struct ucred *cred)
735 if (nch->ncp->nc_flag & NCF_UNRESOLVED) {
737 cache_resolve(nch, cred);
740 error = nch->ncp->nc_error;
741 if (vmode & (VDELETE|VCREATE|VEXCL)) {
742 if (((vmode & VCREATE) && nch->ncp->nc_vp == NULL) ||
743 ((vmode & VDELETE) && nch->ncp->nc_vp != NULL)
745 if ((par.ncp = nch->ncp->nc_parent) == NULL) {
749 par.mount = nch->mount;
751 error = naccess(&par, VWRITE, cred);
755 if ((vmode & VEXCL) && nch->ncp->nc_vp != NULL)
759 error = cache_vget(nch, cred, LK_SHARED, &vp);
760 if (error == ENOENT) {
763 } else if (error == 0) {
764 /* XXX cache the va in the namecache or in the vnode */
765 if ((error = VOP_GETATTR(vp, &va)) == 0) {
766 if ((vmode & VWRITE) && vp->v_mount) {
767 if (vp->v_mount->mnt_flag & MNT_RDONLY)
773 error = naccess_va(&va, vmode, cred);
780 * Check the requested access against the given vattr using cred.
783 naccess_va(struct vattr *va, int vmode, struct ucred *cred)
788 * Test the immutable bit for files, directories, and softlinks.
790 if (vmode & (VWRITE|VDELETE)) {
791 if (va->va_type == VDIR || va->va_type == VLNK || va->va_type == VREG) {
792 if (va->va_flags & IMMUTABLE)
798 * root gets universal access
800 if (cred->cr_uid == 0)
804 * Check owner perms, group perms, and world perms
807 if (cred->cr_uid == va->va_uid) {
808 if ((vmode & va->va_mode) != vmode)
814 for (i = 0; i < cred->cr_ngroups; ++i) {
815 if (va->va_gid == cred->cr_groups[i]) {
816 if ((vmode & va->va_mode) != vmode)
823 if ((vmode & va->va_mode) != vmode)