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,
26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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
35 * nlookup() is the 'new' namei interface. Rather then return directory and
36 * leaf vnodes (in various lock states) the new interface instead deals in
37 * namecache records. Namecache records may represent both a positive or
38 * a negative hit. The namespace is locked via the namecache record instead
39 * of via the vnode, and only the leaf namecache record (representing the
40 * filename) needs to be locked.
42 * This greatly improves filesystem parallelism and is a huge simplification
43 * of the API verses the old vnode locking / namei scheme.
45 * Filesystems must actively control the caching aspects of the namecache,
46 * and since namecache pointers are used as handles they are non-optional
47 * even for filesystems which do not generally wish to cache things. It is
48 * intended that a separate cache coherency API will be constructed to handle
52 #include "opt_ktrace.h"
54 #include <sys/param.h>
55 #include <sys/systm.h>
56 #include <sys/kernel.h>
57 #include <sys/vnode.h>
58 #include <sys/mount.h>
59 #include <sys/filedesc.h>
61 #include <sys/namei.h>
62 #include <sys/nlookup.h>
63 #include <sys/malloc.h>
65 #include <sys/objcache.h>
69 #include <sys/ktrace.h>
72 static int naccess(struct nchandle *nch, 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.
85 nlookup_init(struct nlookupdata *nd,
86 const char *path, enum uio_seg seg, int flags)
97 * note: the pathlen set by copy*str() includes the terminating \0.
99 bzero(nd, sizeof(struct nlookupdata));
100 nd->nl_path = objcache_get(namei_oc, M_WAITOK);
101 nd->nl_flags |= NLC_HASBUF;
102 if (seg == UIO_SYSSPACE)
103 error = copystr(path, nd->nl_path, MAXPATHLEN, &pathlen);
105 error = copyinstr(path, nd->nl_path, MAXPATHLEN, &pathlen);
108 * Don't allow empty pathnames.
109 * POSIX.1 requirement: "" is not a vaild file name.
111 if (error == 0 && pathlen <= 1)
116 cache_copy(&p->p_fd->fd_ncdir, &nd->nl_nch);
117 cache_copy(&p->p_fd->fd_nrdir, &nd->nl_rootnch);
118 if (p->p_fd->fd_njdir.ncp)
119 cache_copy(&p->p_fd->fd_njdir, &nd->nl_jailnch);
120 nd->nl_cred = crhold(p->p_ucred);
122 cache_copy(&rootnch, &nd->nl_nch);
123 cache_copy(&nd->nl_nch, &nd->nl_rootnch);
124 cache_copy(&nd->nl_nch, &nd->nl_jailnch);
125 nd->nl_cred = crhold(proc0.p_ucred);
128 nd->nl_flags |= flags;
137 * nlookup_init() for "at" family of syscalls.
139 * Works similarly to nlookup_init() but if path is relative and fd is not
140 * AT_FDCWD, path is interpreted relative to the directory pointed to by fd.
141 * In this case, the file entry pointed to by fd is ref'ed and returned in
144 * If the call succeeds, nlookup_done_at() must be called to clean-up the nd
145 * and release the ref to the file entry.
148 nlookup_init_at(struct nlookupdata *nd, struct file **fpp, int fd,
149 const char *path, enum uio_seg seg, int flags)
151 struct thread *td = curthread;
152 struct proc *p = td->td_proc;
159 if ((error = nlookup_init(nd, path, seg, flags)) != 0) {
163 if (nd->nl_path[0] != '/' && fd != AT_FDCWD) {
164 if ((error = holdvnode(p->p_fd, fd, &fp)) != 0)
166 vp = (struct vnode*)fp->f_data;
167 if (vp->v_type != VDIR || fp->f_nchandle.ncp == NULL) {
173 cache_drop(&nd->nl_nch);
174 cache_copy(&fp->f_nchandle, &nd->nl_nch);
187 * This works similarly to nlookup_init() but does not assume a process
188 * context. rootnch is always chosen for the root directory and the cred
189 * and starting directory are supplied in arguments.
192 nlookup_init_raw(struct nlookupdata *nd,
193 const char *path, enum uio_seg seg, int flags,
194 struct ucred *cred, struct nchandle *ncstart)
202 bzero(nd, sizeof(struct nlookupdata));
203 nd->nl_path = objcache_get(namei_oc, M_WAITOK);
204 nd->nl_flags |= NLC_HASBUF;
205 if (seg == UIO_SYSSPACE)
206 error = copystr(path, nd->nl_path, MAXPATHLEN, &pathlen);
208 error = copyinstr(path, nd->nl_path, MAXPATHLEN, &pathlen);
211 * Don't allow empty pathnames.
212 * POSIX.1 requirement: "" is not a vaild file name.
214 if (error == 0 && pathlen <= 1)
218 cache_copy(ncstart, &nd->nl_nch);
219 cache_copy(&rootnch, &nd->nl_rootnch);
220 cache_copy(&rootnch, &nd->nl_jailnch);
221 nd->nl_cred = crhold(cred);
223 nd->nl_flags |= flags;
231 * This works similarly to nlookup_init_raw() but does not rely
232 * on rootnch being initialized yet.
235 nlookup_init_root(struct nlookupdata *nd,
236 const char *path, enum uio_seg seg, int flags,
237 struct ucred *cred, struct nchandle *ncstart,
238 struct nchandle *ncroot)
246 bzero(nd, sizeof(struct nlookupdata));
247 nd->nl_path = objcache_get(namei_oc, M_WAITOK);
248 nd->nl_flags |= NLC_HASBUF;
249 if (seg == UIO_SYSSPACE)
250 error = copystr(path, nd->nl_path, MAXPATHLEN, &pathlen);
252 error = copyinstr(path, nd->nl_path, MAXPATHLEN, &pathlen);
255 * Don't allow empty pathnames.
256 * POSIX.1 requirement: "" is not a vaild file name.
258 if (error == 0 && pathlen <= 1)
262 cache_copy(ncstart, &nd->nl_nch);
263 cache_copy(ncroot, &nd->nl_rootnch);
264 cache_copy(ncroot, &nd->nl_jailnch);
265 nd->nl_cred = crhold(cred);
267 nd->nl_flags |= flags;
275 * Set a different credential; this credential will be used by future
276 * operations performed on nd.nl_open_vp and nlookupdata structure.
279 nlookup_set_cred(struct nlookupdata *nd, struct ucred *cred)
281 KKASSERT(nd->nl_cred != NULL);
283 if (nd->nl_cred != cred) {
291 * Cleanup a nlookupdata structure after we are through with it. This may
292 * be called on any nlookupdata structure initialized with nlookup_init().
293 * Calling nlookup_done() is mandatory in all cases except where nlookup_init()
294 * returns an error, even if as a consumer you believe you have taken all
295 * dynamic elements out of the nlookupdata structure.
298 nlookup_done(struct nlookupdata *nd)
300 if (nd->nl_nch.ncp) {
301 if (nd->nl_flags & NLC_NCPISLOCKED) {
302 nd->nl_flags &= ~NLC_NCPISLOCKED;
303 cache_unlock(&nd->nl_nch);
305 cache_drop(&nd->nl_nch); /* NULL's out the nch */
307 if (nd->nl_rootnch.ncp)
308 cache_drop(&nd->nl_rootnch);
309 if (nd->nl_jailnch.ncp)
310 cache_drop(&nd->nl_jailnch);
311 if ((nd->nl_flags & NLC_HASBUF) && nd->nl_path) {
312 objcache_put(namei_oc, nd->nl_path);
319 if (nd->nl_open_vp) {
320 if (nd->nl_flags & NLC_LOCKVP) {
321 vn_unlock(nd->nl_open_vp);
322 nd->nl_flags &= ~NLC_LOCKVP;
324 vn_close(nd->nl_open_vp, nd->nl_vp_fmode);
325 nd->nl_open_vp = NULL;
331 nd->nl_flags = 0; /* clear remaining flags (just clear everything) */
335 * Works similarly to nlookup_done() when nd initialized with
339 nlookup_done_at(struct nlookupdata *nd, struct file *fp)
347 nlookup_zero(struct nlookupdata *nd)
349 bzero(nd, sizeof(struct nlookupdata));
353 * Simple all-in-one nlookup. Returns a locked namecache structure or NULL
354 * if an error occured.
356 * Note that the returned ncp is not checked for permissions, though VEXEC
357 * is checked on the directory path leading up to the result. The caller
358 * must call naccess() to check the permissions of the returned leaf.
361 nlookup_simple(const char *str, enum uio_seg seg,
362 int niflags, int *error)
364 struct nlookupdata nd;
367 *error = nlookup_init(&nd, str, seg, niflags);
369 if ((*error = nlookup(&nd)) == 0) {
370 nch = nd.nl_nch; /* keep hold ref from structure */
371 cache_zero(&nd.nl_nch); /* and NULL out */
383 * Returns non-zero if the path element is the last element
387 islastelement(const char *ptr)
395 * Returns non-zero if we need to lock the namecache element
396 * exclusively. Unless otherwise requested by NLC_SHAREDLOCK,
397 * the last element of the namecache lookup will be locked
400 * NOTE: Even if we return on-zero, an unresolved namecache record
401 * will always be locked exclusively.
405 wantsexcllock(struct nlookupdata *nd, const char *ptr)
407 if ((nd->nl_flags & NLC_SHAREDLOCK) == 0)
408 return(islastelement(ptr));
414 * Do a generic nlookup. Note that the passed nd is not nlookup_done()'d
415 * on return, even if an error occurs. If no error occurs or NLC_CREATE
416 * is flagged and ENOENT is returned, then the returned nl_nch is always
417 * referenced and locked exclusively.
419 * WARNING: For any general error other than ENOENT w/NLC_CREATE, the
420 * the resulting nl_nch may or may not be locked and if locked
421 * might be locked either shared or exclusive.
423 * Intermediate directory elements, including the current directory, require
424 * execute (search) permission. nlookup does not examine the access
425 * permissions on the returned element.
427 * If NLC_CREATE is set the last directory must allow node creation,
428 * and an error code of 0 will be returned for a non-existant
429 * target (not ENOENT).
431 * If NLC_RENAME_DST is set the last directory mut allow node deletion,
432 * plus the sticky check is made, and an error code of 0 will be returned
433 * for a non-existant target (not ENOENT).
435 * If NLC_DELETE is set the last directory mut allow node deletion,
436 * plus the sticky check is made.
438 * If NLC_REFDVP is set nd->nl_dvp will be set to the directory vnode
439 * of the returned entry. The vnode will be referenced, but not locked,
440 * and will be released by nlookup_done() along with everything else.
442 * NOTE: As an optimization we attempt to obtain a shared namecache lock
443 * on any intermediate elements. On success, the returned element
444 * is ALWAYS locked exclusively.
447 nlookup(struct nlookupdata *nd)
449 globaldata_t gd = mycpu;
450 struct nlcomponent nlc;
453 struct nchandle nctmp;
455 struct vnode *hvp; /* hold to prevent recyclement */
464 if (KTRPOINT(nd->nl_td, KTR_NAMEI))
465 ktrnamei(nd->nl_td->td_lwp, nd->nl_path);
467 bzero(&nlc, sizeof(nlc));
470 * Setup for the loop. The current working namecache element is
471 * always at least referenced. We lock it as required, but always
472 * return a locked, resolved namecache entry.
482 * Loop on the path components. At the top of the loop nd->nl_nch
483 * is ref'd and unlocked and represents our current position.
487 * Make sure nl_nch is locked so we can access the vnode, resolution
490 if ((nd->nl_flags & NLC_NCPISLOCKED) == 0) {
491 nd->nl_flags |= NLC_NCPISLOCKED;
492 cache_lock_maybe_shared(&nd->nl_nch, wantsexcllock(nd, ptr));
496 * Check if the root directory should replace the current
497 * directory. This is done at the start of a translation
498 * or after a symbolic link has been found. In other cases
499 * ptr will never be pointing at a '/'.
504 } while (*ptr == '/');
505 cache_unlock(&nd->nl_nch);
506 cache_get_maybe_shared(&nd->nl_rootnch, &nch,
507 wantsexcllock(nd, ptr));
508 cache_drop(&nd->nl_nch);
509 nd->nl_nch = nch; /* remains locked */
512 * Fast-track termination. There is no parent directory of
513 * the root in the same mount from the point of view of
514 * the caller so return EACCES if NLC_REFDVP is specified,
515 * and EEXIST if NLC_CREATE is also specified.
516 * e.g. 'rmdir /' or 'mkdir /' are not allowed.
519 if (nd->nl_flags & NLC_REFDVP)
520 error = (nd->nl_flags & NLC_CREATE) ? EEXIST : EACCES;
529 * Check directory search permissions (nd->nl_nch is locked & refd)
532 error = naccess(&nd->nl_nch, NLC_EXEC, nd->nl_cred, &dflags);
537 * Extract the path component. Path components are limited to
540 nlc.nlc_nameptr = ptr;
541 while (*ptr && *ptr != '/')
543 nlc.nlc_namelen = ptr - nlc.nlc_nameptr;
544 if (nlc.nlc_namelen >= 256) {
545 error = ENAMETOOLONG;
550 * Lookup the path component in the cache, creating an unresolved
551 * entry if necessary. We have to handle "." and ".." as special
554 * When handling ".." we have to detect a traversal back through a
555 * mount point. If we are at the root, ".." just returns the root.
557 * When handling "." or ".." we also have to recalculate dflags
558 * since our dflags will be for some sub-directory instead of the
561 * This subsection returns a locked, refd 'nch' unless it errors out,
562 * and an unlocked but still ref'd nd->nl_nch.
564 * The namecache topology is not allowed to be disconnected, so
565 * encountering a NULL parent will generate EINVAL. This typically
566 * occurs when a directory is removed out from under a process.
568 * WARNING! The unlocking of nd->nl_nch is sensitive code.
570 KKASSERT(nd->nl_flags & NLC_NCPISLOCKED);
572 if (nlc.nlc_namelen == 1 && nlc.nlc_nameptr[0] == '.') {
573 cache_unlock(&nd->nl_nch);
574 nd->nl_flags &= ~NLC_NCPISLOCKED;
575 cache_get_maybe_shared(&nd->nl_nch, &nch, wantsexcllock(nd, ptr));
577 } else if (nlc.nlc_namelen == 2 &&
578 nlc.nlc_nameptr[0] == '.' && nlc.nlc_nameptr[1] == '.') {
579 if (nd->nl_nch.mount == nd->nl_rootnch.mount &&
580 nd->nl_nch.ncp == nd->nl_rootnch.ncp
583 * ".." at the root returns the root
585 cache_unlock(&nd->nl_nch);
586 nd->nl_flags &= ~NLC_NCPISLOCKED;
587 cache_get_maybe_shared(&nd->nl_nch, &nch,
588 wantsexcllock(nd, ptr));
591 * Locate the parent ncp. If we are at the root of a
592 * filesystem mount we have to skip to the mounted-on
593 * point in the underlying filesystem.
595 * Expect the parent to always be good since the
596 * mountpoint doesn't go away. XXX hack. cache_get()
597 * requires the ncp to already have a ref as a safety.
600 while (nctmp.ncp == nctmp.mount->mnt_ncmountpt.ncp)
601 nctmp = nctmp.mount->mnt_ncmounton;
602 nctmp.ncp = nctmp.ncp->nc_parent;
603 KKASSERT(nctmp.ncp != NULL);
605 cache_unlock(&nd->nl_nch);
606 nd->nl_flags &= ~NLC_NCPISLOCKED;
607 cache_get_maybe_shared(&nctmp, &nch, wantsexcllock(nd, ptr));
608 cache_drop(&nctmp); /* NOTE: zero's nctmp */
613 * Must unlock nl_nch when traversing down the path. However,
614 * the child ncp has not yet been found/created and the parent's
615 * child list might be empty. Thus releasing the lock can
616 * allow a race whereby the parent ncp's vnode is recycled.
617 * This case can occur especially when maxvnodes is set very low.
619 * We need the parent's ncp to remain resolved for all normal
620 * filesystem activities, so we vhold() the vp during the lookup
621 * to prevent recyclement due to vnlru / maxvnodes.
623 * If we race an unlink or rename the ncp might be marked
624 * DESTROYED after resolution, requiring a retry.
626 if ((hvp = nd->nl_nch.ncp->nc_vp) != NULL)
628 cache_unlock(&nd->nl_nch);
629 nd->nl_flags &= ~NLC_NCPISLOCKED;
630 error = cache_nlookup_maybe_shared(&nd->nl_nch, &nlc,
631 wantsexcllock(nd, ptr), &nch);
632 if (error == EWOULDBLOCK) {
633 nch = cache_nlookup(&nd->nl_nch, &nlc);
634 if (nch.ncp->nc_flag & NCF_UNRESOLVED)
637 error = cache_resolve(&nch, nd->nl_cred);
638 if (error != EAGAIN &&
639 (nch.ncp->nc_flag & NCF_DESTROYED) == 0) {
642 kprintf("[diagnostic] nlookup: relookup %*.*s\n",
643 nch.ncp->nc_nlen, nch.ncp->nc_nlen,
646 nch = cache_nlookup(&nd->nl_nch, &nlc);
655 * If the last component was "." or ".." our dflags no longer
656 * represents the parent directory and we have to explicitly
659 * Expect the parent to be good since nch is locked.
661 if (wasdotordotdot && error == 0) {
663 if ((par.ncp = nch.ncp->nc_parent) != NULL) {
664 par.mount = nch.mount;
666 cache_lock_maybe_shared(&par, wantsexcllock(nd, ptr));
667 error = naccess(&par, 0, nd->nl_cred, &dflags);
673 * [end of subsection]
675 * nch is locked and referenced.
676 * nd->nl_nch is unlocked and referenced.
678 * nl_nch must be unlocked or we could chain lock to the root
679 * if a resolve gets stuck (e.g. in NFS).
681 KKASSERT((nd->nl_flags & NLC_NCPISLOCKED) == 0);
684 * Resolve the namespace if necessary. The ncp returned by
685 * cache_nlookup() is referenced and locked.
687 * XXX neither '.' nor '..' should return EAGAIN since they were
688 * previously resolved and thus cannot be newly created ncp's.
690 if (nch.ncp->nc_flag & NCF_UNRESOLVED) {
692 error = cache_resolve(&nch, nd->nl_cred);
693 KKASSERT(error != EAGAIN);
695 error = nch.ncp->nc_error;
699 * Early completion. ENOENT is not an error if this is the last
700 * component and NLC_CREATE or NLC_RENAME (rename target) was
701 * requested. Note that ncp->nc_error is left as ENOENT in that
702 * case, which we check later on.
704 * Also handle invalid '.' or '..' components terminating a path
705 * for a create/rename/delete. The standard requires this and pax
706 * pretty stupidly depends on it.
708 if (islastelement(ptr)) {
709 if (error == ENOENT &&
710 (nd->nl_flags & (NLC_CREATE | NLC_RENAME_DST))
712 if (nd->nl_flags & NLC_NFS_RDONLY) {
715 error = naccess(&nch, nd->nl_flags | dflags,
719 if (error == 0 && wasdotordotdot &&
720 (nd->nl_flags & (NLC_CREATE | NLC_DELETE |
721 NLC_RENAME_SRC | NLC_RENAME_DST))) {
725 if (nd->nl_flags & NLC_CREATE)
727 else if (nd->nl_flags & NLC_DELETE)
728 error = (wasdotordotdot == 1) ? EINVAL : ENOTEMPTY;
735 * Early completion on error.
743 * If the element is a symlink and it is either not the last
744 * element or it is the last element and we are allowed to
745 * follow symlinks, resolve the symlink.
747 if ((nch.ncp->nc_flag & NCF_ISSYMLINK) &&
748 (*ptr || (nd->nl_flags & NLC_FOLLOW))
750 if (nd->nl_loopcnt++ >= MAXSYMLINKS) {
755 error = nreadsymlink(nd, &nch, &nlc);
761 * Concatenate trailing path elements onto the returned symlink.
762 * Note that if the path component (ptr) is not exhausted, it
763 * will being with a '/', so we do not have to add another one.
765 * The symlink may not be empty.
768 if (nlc.nlc_namelen == 0 || nlc.nlc_namelen + len >= MAXPATHLEN) {
769 error = nlc.nlc_namelen ? ENAMETOOLONG : ENOENT;
770 objcache_put(namei_oc, nlc.nlc_nameptr);
773 bcopy(ptr, nlc.nlc_nameptr + nlc.nlc_namelen, len + 1);
774 if (nd->nl_flags & NLC_HASBUF)
775 objcache_put(namei_oc, nd->nl_path);
776 nd->nl_path = nlc.nlc_nameptr;
777 nd->nl_flags |= NLC_HASBUF;
781 * Go back up to the top to resolve any initial '/'s in the
788 * If the element is a directory and we are crossing a mount point,
791 while ((nch.ncp->nc_flag & NCF_ISMOUNTPT) &&
792 (nd->nl_flags & NLC_NOCROSSMOUNT) == 0 &&
793 (mp = cache_findmount(&nch)) != NULL
799 * VFS must be busied before the namecache entry is locked,
800 * but we don't want to waste time calling vfs_busy() if the
801 * mount point is already resolved.
806 while (vfs_busy(mp, 0)) {
807 if (mp->mnt_kern_flag & MNTK_UNMOUNT) {
808 kprintf("nlookup: warning umount race avoided\n");
816 cache_get_maybe_shared(&mp->mnt_ncmountpt, &nch,
817 wantsexcllock(nd, ptr));
819 if (nch.ncp->nc_flag & NCF_UNRESOLVED) {
820 if (vfs_do_busy == 0) {
824 error = VFS_ROOT(mp, &tdp);
831 cache_setvp(&nch, tdp);
846 * Skip any slashes to get to the next element. If there
847 * are any slashes at all the current element must be a
848 * directory or, in the create case, intended to become a directory.
849 * If it isn't we break without incrementing ptr and fall through
850 * to the failure case below.
852 while (*ptr == '/') {
853 if ((nch.ncp->nc_flag & NCF_ISDIR) == 0 &&
854 !(nd->nl_flags & NLC_WILLBEDIR)
862 * Continuation case: additional elements and the current
863 * element is a directory.
865 if (*ptr && (nch.ncp->nc_flag & NCF_ISDIR)) {
866 cache_drop(&nd->nl_nch);
868 KKASSERT((nd->nl_flags & NLC_NCPISLOCKED) == 0);
874 * Failure case: additional elements and the current element
884 * Successful lookup of last element.
886 * Check permissions if the target exists. If the target does not
887 * exist directory permissions were already tested in the early
888 * completion code above.
890 * nd->nl_flags will be adjusted on return with NLC_APPENDONLY
891 * if the file is marked append-only, and NLC_STICKY if the directory
892 * containing the file is sticky.
894 if (nch.ncp->nc_vp && (nd->nl_flags & NLC_ALLCHKS)) {
895 error = naccess(&nch, nd->nl_flags | dflags,
904 * Termination: no more elements.
906 * If NLC_REFDVP is set acquire a referenced parent dvp.
908 if (nd->nl_flags & NLC_REFDVP) {
909 cache_lock(&nd->nl_nch);
910 error = cache_vref(&nd->nl_nch, nd->nl_cred, &nd->nl_dvp);
911 cache_unlock(&nd->nl_nch);
913 kprintf("NLC_REFDVP: Cannot ref dvp of %p\n", nch.ncp);
918 cache_drop(&nd->nl_nch);
920 nd->nl_flags |= NLC_NCPISLOCKED;
926 ++gd->gd_nchstats->ncs_longhits;
928 ++gd->gd_nchstats->ncs_longmiss;
930 if (nd->nl_flags & NLC_NCPISLOCKED)
931 KKASSERT(cache_lockstatus(&nd->nl_nch) > 0);
934 * NOTE: If NLC_CREATE was set the ncp may represent a negative hit
935 * (ncp->nc_error will be ENOENT), but we will still return an error
942 * Resolve a mount point's glue ncp. This ncp connects creates the illusion
943 * of continuity in the namecache tree by connecting the ncp related to the
944 * vnode under the mount to the ncp related to the mount's root vnode.
946 * If no error occured a locked, ref'd ncp is stored in *ncpp.
949 nlookup_mp(struct mount *mp, struct nchandle *nch)
955 cache_get(&mp->mnt_ncmountpt, nch);
956 if (nch->ncp->nc_flag & NCF_UNRESOLVED) {
957 while (vfs_busy(mp, 0))
959 error = VFS_ROOT(mp, &vp);
964 cache_setvp(nch, vp);
972 * Read the contents of a symlink, allocate a path buffer out of the
973 * namei_oc and initialize the supplied nlcomponent with the result.
975 * If an error occurs no buffer will be allocated or returned in the nlc.
978 nreadsymlink(struct nlookupdata *nd, struct nchandle *nch,
979 struct nlcomponent *nlc)
988 nlc->nlc_nameptr = NULL;
989 nlc->nlc_namelen = 0;
990 if (nch->ncp->nc_vp == NULL)
992 if ((error = cache_vget(nch, nd->nl_cred, LK_SHARED, &vp)) != 0)
994 cp = objcache_get(namei_oc, M_WAITOK);
996 aiov.iov_len = MAXPATHLEN;
997 auio.uio_iov = &aiov;
1000 auio.uio_rw = UIO_READ;
1001 auio.uio_segflg = UIO_SYSSPACE;
1002 auio.uio_td = nd->nl_td;
1003 auio.uio_resid = MAXPATHLEN - 1;
1004 error = VOP_READLINK(vp, &auio, nd->nl_cred);
1007 linklen = MAXPATHLEN - 1 - auio.uio_resid;
1008 if (varsym_enable) {
1009 linklen = varsymreplace(cp, linklen, MAXPATHLEN - 1);
1011 error = ENAMETOOLONG;
1016 nlc->nlc_nameptr = cp;
1017 nlc->nlc_namelen = linklen;
1021 objcache_put(namei_oc, cp);
1027 * Check access [XXX cache vattr!] [XXX quota]
1029 * Generally check the NLC_* access bits. All specified bits must pass
1030 * for this function to return 0.
1032 * The file does not have to exist when checking NLC_CREATE or NLC_RENAME_DST
1033 * access, otherwise it must exist. No error is returned in this case.
1035 * The file must not exist if NLC_EXCL is specified.
1037 * Directory permissions in general are tested for NLC_CREATE if the file
1038 * does not exist, NLC_DELETE if the file does exist, and NLC_RENAME_DST
1039 * whether the file exists or not.
1041 * The directory sticky bit is tested for NLC_DELETE and NLC_RENAME_DST,
1042 * the latter is only tested if the target exists.
1044 * The passed ncp must be referenced and locked. If it is already resolved
1045 * it may be locked shared but otherwise should be locked exclusively.
1048 naccess(struct nchandle *nch, int nflags, struct ucred *cred, int *nflagsp)
1052 struct namecache *ncp;
1056 KKASSERT(cache_lockstatus(nch) > 0);
1059 if (ncp->nc_flag & NCF_UNRESOLVED) {
1060 cache_resolve(nch, cred);
1063 error = ncp->nc_error;
1066 * Directory permissions checks. Silently ignore ENOENT if these
1067 * tests pass. It isn't an error.
1069 * We can safely resolve ncp->nc_parent because ncp is currently
1072 if (nflags & (NLC_CREATE | NLC_DELETE | NLC_RENAME_SRC | NLC_RENAME_DST)) {
1073 if (((nflags & NLC_CREATE) && ncp->nc_vp == NULL) ||
1074 ((nflags & NLC_DELETE) && ncp->nc_vp != NULL) ||
1075 ((nflags & NLC_RENAME_SRC) && ncp->nc_vp != NULL) ||
1076 (nflags & NLC_RENAME_DST)
1078 struct nchandle par;
1080 if ((par.ncp = ncp->nc_parent) == NULL) {
1081 if (error != EAGAIN)
1083 } else if (error == 0 || error == ENOENT) {
1084 par.mount = nch->mount;
1086 cache_lock_maybe_shared(&par, 0);
1087 error = naccess(&par, NLC_WRITE, cred, NULL);
1094 * NLC_EXCL check. Target file must not exist.
1096 if (error == 0 && (nflags & NLC_EXCL) && ncp->nc_vp != NULL)
1100 * Get the vnode attributes so we can do the rest of our checks.
1102 * NOTE: We only call naccess_va() if the target exists.
1105 error = cache_vget(nch, cred, LK_SHARED, &vp);
1106 if (error == ENOENT) {
1108 * Silently zero-out ENOENT if creating or renaming
1109 * (rename target). It isn't an error.
1111 if (nflags & (NLC_CREATE | NLC_RENAME_DST))
1113 } else if (error == 0) {
1115 * Get the vnode attributes and check for illegal O_TRUNC
1116 * requests and read-only mounts.
1118 * NOTE: You can still open devices on read-only mounts for
1121 * NOTE: creates/deletes/renames are handled by the NLC_WRITE
1122 * check on the parent directory above.
1124 * XXX cache the va in the namecache or in the vnode
1126 error = VOP_GETATTR(vp, &va);
1127 if (error == 0 && (nflags & NLC_TRUNCATE)) {
1128 switch(va.va_type) {
1143 if (error == 0 && (nflags & NLC_WRITE) && vp->v_mount &&
1144 (vp->v_mount->mnt_flag & MNT_RDONLY)
1146 switch(va.va_type) {
1160 * Check permissions based on file attributes. The passed
1161 * flags (*nflagsp) are modified with feedback based on
1162 * special attributes and requirements.
1166 * Adjust the returned (*nflagsp) if non-NULL.
1169 if ((va.va_mode & VSVTX) && va.va_uid != cred->cr_uid)
1170 *nflagsp |= NLC_STICKY;
1171 if (va.va_flags & APPEND)
1172 *nflagsp |= NLC_APPENDONLY;
1173 if (va.va_flags & IMMUTABLE)
1174 *nflagsp |= NLC_IMMUTABLE;
1178 * Track swapcache management flags in the namecache.
1180 * Calculate the flags based on the current vattr info
1181 * and recalculate the inherited flags from the parent
1182 * (the original cache linkage may have occurred without
1183 * getattrs and thus have stale flags).
1186 if (va.va_flags & SF_NOCACHE)
1187 cflags |= NCF_SF_NOCACHE;
1188 if (va.va_flags & UF_CACHE)
1189 cflags |= NCF_UF_CACHE;
1190 if (ncp->nc_parent) {
1191 if (ncp->nc_parent->nc_flag &
1192 (NCF_SF_NOCACHE | NCF_SF_PNOCACHE)) {
1193 cflags |= NCF_SF_PNOCACHE;
1195 if (ncp->nc_parent->nc_flag &
1196 (NCF_UF_CACHE | NCF_UF_PCACHE)) {
1197 cflags |= NCF_UF_PCACHE;
1202 * XXX we're not supposed to update nc_flag when holding
1205 atomic_clear_short(&ncp->nc_flag,
1206 (NCF_SF_NOCACHE | NCF_UF_CACHE |
1207 NCF_SF_PNOCACHE | NCF_UF_PCACHE) & ~cflags);
1208 atomic_set_short(&ncp->nc_flag, cflags);
1211 * Process general access.
1213 error = naccess_va(&va, nflags, cred);
1221 * Check the requested access against the given vattr using cred.
1224 naccess_va(struct vattr *va, int nflags, struct ucred *cred)
1230 * Test the immutable bit. Creations, deletions, renames (source
1231 * or destination) are not allowed. chown/chmod/other is also not
1232 * allowed but is handled by SETATTR. Hardlinks to the immutable
1235 * If the directory is set to immutable then creations, deletions,
1236 * renames (source or dest) and hardlinks to files within the directory
1237 * are not allowed, and regular files opened through the directory may
1238 * not be written to or truncated (unless a special device).
1240 * NOTE! New hardlinks to immutable files work but new hardlinks to
1241 * files, immutable or not, sitting inside an immutable directory are
1242 * not allowed. As always if the file is hardlinked via some other
1243 * path additional hardlinks may be possible even if the file is marked
1244 * immutable. The sysop needs to create a closure by checking the hard
1245 * link count. Once closure is achieved you are good, and security
1246 * scripts should check link counts anyway.
1248 * Writes and truncations are only allowed on special devices.
1250 if ((va->va_flags & IMMUTABLE) || (nflags & NLC_IMMUTABLE)) {
1251 if ((nflags & NLC_IMMUTABLE) && (nflags & NLC_HLINK))
1253 if (nflags & (NLC_CREATE | NLC_DELETE |
1254 NLC_RENAME_SRC | NLC_RENAME_DST)) {
1257 if (nflags & (NLC_WRITE | NLC_TRUNCATE)) {
1258 switch(va->va_type) {
1272 * Test the no-unlink and append-only bits for opens, rename targets,
1273 * and deletions. These bits are not tested for creations or
1276 * Unlike FreeBSD we allow a file with APPEND set to be renamed.
1277 * If you do not wish this you must also set NOUNLINK.
1279 * If the governing directory is marked APPEND-only it implies
1280 * NOUNLINK for all entries in the directory.
1282 if (((va->va_flags & NOUNLINK) || (nflags & NLC_APPENDONLY)) &&
1283 (nflags & (NLC_DELETE | NLC_RENAME_SRC | NLC_RENAME_DST))
1289 * A file marked append-only may not be deleted but can be renamed.
1291 if ((va->va_flags & APPEND) &&
1292 (nflags & (NLC_DELETE | NLC_RENAME_DST))
1298 * A file marked append-only which is opened for writing must also
1299 * be opened O_APPEND.
1301 if ((va->va_flags & APPEND) && (nflags & (NLC_OPEN | NLC_TRUNCATE))) {
1302 if (nflags & NLC_TRUNCATE)
1304 if ((nflags & (NLC_OPEN | NLC_WRITE)) == (NLC_OPEN | NLC_WRITE)) {
1305 if ((nflags & NLC_APPEND) == 0)
1311 * root gets universal access
1313 if (cred->cr_uid == 0)
1317 * Check owner perms.
1319 * If NLC_OWN is set the owner of the file is allowed no matter when
1320 * the owner-mode bits say (utimes).
1323 if (nflags & NLC_READ)
1325 if (nflags & NLC_WRITE)
1327 if (nflags & NLC_EXEC)
1330 if (cred->cr_uid == va->va_uid) {
1331 if ((nflags & NLC_OWN) == 0) {
1332 if ((vmode & va->va_mode) != vmode)
1339 * If NLC_STICKY is set only the owner may delete or rename a file.
1340 * This bit is typically set on /tmp.
1342 * Note that the NLC_READ/WRITE/EXEC bits are not typically set in
1343 * the specific delete or rename case. For deletions and renames we
1344 * usually just care about directory permissions, not file permissions.
1346 if ((nflags & NLC_STICKY) &&
1347 (nflags & (NLC_RENAME_SRC | NLC_RENAME_DST | NLC_DELETE))) {
1355 for (i = 0; i < cred->cr_ngroups; ++i) {
1356 if (va->va_gid == cred->cr_groups[i]) {
1357 if ((vmode & va->va_mode) != vmode)
1367 if ((vmode & va->va_mode) != vmode)