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
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>
71 #include <sys/ktrace.h>
75 * Initialize a nlookup() structure, early error return for copyin faults
76 * or a degenerate empty string (which is not allowed).
78 * The first process proc0's credentials are used if the calling thread
79 * is not associated with a process context.
82 nlookup_init(struct nlookupdata *nd,
83 const char *path, enum uio_seg seg, int flags)
94 * note: the pathlen set by copy*str() includes the terminating \0.
96 bzero(nd, sizeof(struct nlookupdata));
97 nd->nl_path = objcache_get(namei_oc, M_WAITOK);
98 nd->nl_flags |= NLC_HASBUF;
99 if (seg == UIO_SYSSPACE)
100 error = copystr(path, nd->nl_path, MAXPATHLEN, &pathlen);
102 error = copyinstr(path, nd->nl_path, MAXPATHLEN, &pathlen);
105 * Don't allow empty pathnames.
106 * POSIX.1 requirement: "" is not a vaild file name.
108 if (error == 0 && pathlen <= 1)
113 cache_copy(&p->p_fd->fd_ncdir, &nd->nl_nch);
114 cache_copy(&p->p_fd->fd_nrdir, &nd->nl_rootnch);
115 if (p->p_fd->fd_njdir.ncp)
116 cache_copy(&p->p_fd->fd_njdir, &nd->nl_jailnch);
117 nd->nl_cred = crhold(p->p_ucred);
119 cache_copy(&rootnch, &nd->nl_nch);
120 cache_copy(&nd->nl_nch, &nd->nl_rootnch);
121 cache_copy(&nd->nl_nch, &nd->nl_jailnch);
122 nd->nl_cred = crhold(proc0.p_ucred);
125 nd->nl_flags |= flags;
134 * nlookup_init() for "at" family of syscalls.
136 * Works similarly to nlookup_init() but if path is relative and fd is not
137 * AT_FDCWD, path is interpreted relative to the directory pointed to by fd.
138 * In this case, the file entry pointed to by fd is ref'ed and returned in
141 * If the call succeeds, nlookup_done_at() must be called to clean-up the nd
142 * and release the ref to the file entry.
145 nlookup_init_at(struct nlookupdata *nd, struct file **fpp, int fd,
146 const char *path, enum uio_seg seg, int flags)
148 struct thread *td = curthread;
149 struct proc *p = td->td_proc;
156 if ((error = nlookup_init(nd, path, seg, flags)) != 0) {
160 if (nd->nl_path[0] != '/' && fd != AT_FDCWD) {
161 if ((error = holdvnode(p->p_fd, fd, &fp)) != 0)
163 vp = (struct vnode*)fp->f_data;
164 if (vp->v_type != VDIR || fp->f_nchandle.ncp == NULL) {
170 cache_drop(&nd->nl_nch);
171 cache_copy(&fp->f_nchandle, &nd->nl_nch);
184 * This works similarly to nlookup_init() but does not assume a process
185 * context. rootnch is always chosen for the root directory and the cred
186 * and starting directory are supplied in arguments.
189 nlookup_init_raw(struct nlookupdata *nd,
190 const char *path, enum uio_seg seg, int flags,
191 struct ucred *cred, struct nchandle *ncstart)
199 bzero(nd, sizeof(struct nlookupdata));
200 nd->nl_path = objcache_get(namei_oc, M_WAITOK);
201 nd->nl_flags |= NLC_HASBUF;
202 if (seg == UIO_SYSSPACE)
203 error = copystr(path, nd->nl_path, MAXPATHLEN, &pathlen);
205 error = copyinstr(path, nd->nl_path, MAXPATHLEN, &pathlen);
208 * Don't allow empty pathnames.
209 * POSIX.1 requirement: "" is not a vaild file name.
211 if (error == 0 && pathlen <= 1)
215 cache_copy(ncstart, &nd->nl_nch);
216 cache_copy(&rootnch, &nd->nl_rootnch);
217 cache_copy(&rootnch, &nd->nl_jailnch);
218 nd->nl_cred = crhold(cred);
220 nd->nl_flags |= flags;
228 * Set a different credential; this credential will be used by future
229 * operations performed on nd.nl_open_vp and nlookupdata structure.
232 nlookup_set_cred(struct nlookupdata *nd, struct ucred *cred)
234 KKASSERT(nd->nl_cred != NULL);
236 if (nd->nl_cred != cred) {
244 * Cleanup a nlookupdata structure after we are through with it. This may
245 * be called on any nlookupdata structure initialized with nlookup_init().
246 * Calling nlookup_done() is mandatory in all cases except where nlookup_init()
247 * returns an error, even if as a consumer you believe you have taken all
248 * dynamic elements out of the nlookupdata structure.
251 nlookup_done(struct nlookupdata *nd)
253 if (nd->nl_nch.ncp) {
254 if (nd->nl_flags & NLC_NCPISLOCKED) {
255 nd->nl_flags &= ~NLC_NCPISLOCKED;
256 cache_unlock(&nd->nl_nch);
258 cache_drop(&nd->nl_nch);
260 if (nd->nl_rootnch.ncp)
261 cache_drop(&nd->nl_rootnch);
262 if (nd->nl_jailnch.ncp)
263 cache_drop(&nd->nl_jailnch);
264 if ((nd->nl_flags & NLC_HASBUF) && nd->nl_path) {
265 objcache_put(namei_oc, nd->nl_path);
272 if (nd->nl_open_vp) {
273 if (nd->nl_flags & NLC_LOCKVP) {
274 vn_unlock(nd->nl_open_vp);
275 nd->nl_flags &= ~NLC_LOCKVP;
277 vn_close(nd->nl_open_vp, nd->nl_vp_fmode);
278 nd->nl_open_vp = NULL;
284 nd->nl_flags = 0; /* clear remaining flags (just clear everything) */
288 * Works similarly to nlookup_done() when nd initialized with
292 nlookup_done_at(struct nlookupdata *nd, struct file *fp)
300 nlookup_zero(struct nlookupdata *nd)
302 bzero(nd, sizeof(struct nlookupdata));
306 * Simple all-in-one nlookup. Returns a locked namecache structure or NULL
307 * if an error occured.
309 * Note that the returned ncp is not checked for permissions, though VEXEC
310 * is checked on the directory path leading up to the result. The caller
311 * must call naccess() to check the permissions of the returned leaf.
314 nlookup_simple(const char *str, enum uio_seg seg,
315 int niflags, int *error)
317 struct nlookupdata nd;
320 *error = nlookup_init(&nd, str, seg, niflags);
322 if ((*error = nlookup(&nd)) == 0) {
323 nch = nd.nl_nch; /* keep hold ref from structure */
324 cache_zero(&nd.nl_nch); /* and NULL out */
336 * Do a generic nlookup. Note that the passed nd is not nlookup_done()'d
337 * on return, even if an error occurs. If no error occurs the returned
338 * nl_nch is always referenced and locked, otherwise it may or may not be.
340 * Intermediate directory elements, including the current directory, require
341 * execute (search) permission. nlookup does not examine the access
342 * permissions on the returned element.
344 * If NLC_CREATE is set the last directory must allow node creation,
345 * and an error code of 0 will be returned for a non-existant
346 * target (not ENOENT).
348 * If NLC_RENAME_DST is set the last directory mut allow node deletion,
349 * plus the sticky check is made, and an error code of 0 will be returned
350 * for a non-existant target (not ENOENT).
352 * If NLC_DELETE is set the last directory mut allow node deletion,
353 * plus the sticky check is made.
355 * If NLC_REFDVP is set nd->nl_dvp will be set to the directory vnode
356 * of the returned entry. The vnode will be referenced, but not locked,
357 * and will be released by nlookup_done() along with everything else.
360 nlookup(struct nlookupdata *nd)
362 struct nlcomponent nlc;
374 if (KTRPOINT(nd->nl_td, KTR_NAMEI))
375 ktrnamei(nd->nl_td->td_lwp, nd->nl_path);
377 bzero(&nlc, sizeof(nlc));
380 * Setup for the loop. The current working namecache element must
381 * be in a refd + unlocked state. This typically the case on entry except
382 * when stringing nlookup()'s along in a chain, since nlookup() always
383 * returns nl_nch in a locked state.
386 if (nd->nl_flags & NLC_NCPISLOCKED) {
387 nd->nl_flags &= ~NLC_NCPISLOCKED;
388 cache_unlock(&nd->nl_nch);
397 * Loop on the path components. At the top of the loop nd->nl_nch
398 * is ref'd and unlocked and represents our current position.
402 * Check if the root directory should replace the current
403 * directory. This is done at the start of a translation
404 * or after a symbolic link has been found. In other cases
405 * ptr will never be pointing at a '/'.
410 } while (*ptr == '/');
411 cache_copy(&nd->nl_rootnch, &nch);
412 cache_drop(&nd->nl_nch);
416 * Fast-track termination. There is no parent directory of
417 * the root in the same mount from the point of view of
418 * the caller so return EPERM if NLC_REFDVP is specified.
419 * e.g. 'rmdir /' is not allowed.
422 if (nd->nl_flags & NLC_REFDVP) {
425 cache_lock(&nd->nl_nch);
426 nd->nl_flags |= NLC_NCPISLOCKED;
435 * Check directory search permissions.
438 if ((error = naccess(&nd->nl_nch, NLC_EXEC, nd->nl_cred, &dflags)) != 0)
442 * Extract the path component. Path components are limited to
445 nlc.nlc_nameptr = ptr;
446 while (*ptr && *ptr != '/')
448 nlc.nlc_namelen = ptr - nlc.nlc_nameptr;
449 if (nlc.nlc_namelen >= 256) {
450 error = ENAMETOOLONG;
455 * Lookup the path component in the cache, creating an unresolved
456 * entry if necessary. We have to handle "." and ".." as special
459 * When handling ".." we have to detect a traversal back through a
460 * mount point. If we are at the root, ".." just returns the root.
462 * When handling "." or ".." we also have to recalculate dflags
463 * since our dflags will be for some sub-directory instead of the
466 * This subsection returns a locked, refd 'nch' unless it errors out.
467 * The namecache topology is not allowed to be disconnected, so
468 * encountering a NULL parent will generate EINVAL. This typically
469 * occurs when a directory is removed out from under a process.
471 if (nlc.nlc_namelen == 1 && nlc.nlc_nameptr[0] == '.') {
472 cache_get(&nd->nl_nch, &nch);
474 } else if (nlc.nlc_namelen == 2 &&
475 nlc.nlc_nameptr[0] == '.' && nlc.nlc_nameptr[1] == '.') {
476 if (nd->nl_nch.mount == nd->nl_rootnch.mount &&
477 nd->nl_nch.ncp == nd->nl_rootnch.ncp
480 * ".." at the root returns the root
482 cache_get(&nd->nl_nch, &nch);
485 * Locate the parent ncp. If we are at the root of a
486 * filesystem mount we have to skip to the mounted-on
487 * point in the underlying filesystem.
490 while (nch.ncp == nch.mount->mnt_ncmountpt.ncp)
491 nch = nch.mount->mnt_ncmounton;
492 nch.ncp = nch.ncp->nc_parent;
493 KKASSERT(nch.ncp != NULL);
494 cache_get(&nch, &nch);
498 nch = cache_nlookup(&nd->nl_nch, &nlc);
499 while ((error = cache_resolve(&nch, nd->nl_cred)) == EAGAIN) {
500 kprintf("[diagnostic] nlookup: relookup %*.*s\n",
501 nch.ncp->nc_nlen, nch.ncp->nc_nlen, nch.ncp->nc_name);
503 nch = cache_nlookup(&nd->nl_nch, &nlc);
509 * If the last component was "." or ".." our dflags no longer
510 * represents the parent directory and we have to explicitly
513 if (wasdotordotdot && error == 0) {
515 if ((par.ncp = nch.ncp->nc_parent) != NULL) {
516 par.mount = nch.mount;
519 error = naccess(&par, 0, nd->nl_cred, &dflags);
525 * [end of subsection] ncp is locked and ref'd. nd->nl_nch is ref'd
529 * Resolve the namespace if necessary. The ncp returned by
530 * cache_nlookup() is referenced and locked.
532 * XXX neither '.' nor '..' should return EAGAIN since they were
533 * previously resolved and thus cannot be newly created ncp's.
535 if (nch.ncp->nc_flag & NCF_UNRESOLVED) {
536 error = cache_resolve(&nch, nd->nl_cred);
537 KKASSERT(error != EAGAIN);
539 error = nch.ncp->nc_error;
543 * Early completion. ENOENT is not an error if this is the last
544 * component and NLC_CREATE or NLC_RENAME (rename target) was
545 * requested. Note that ncp->nc_error is left as ENOENT in that
546 * case, which we check later on.
548 * Also handle invalid '.' or '..' components terminating a path
549 * for a create/rename/delete. The standard requires this and pax
550 * pretty stupidly depends on it.
552 for (xptr = ptr; *xptr == '/'; ++xptr)
555 if (error == ENOENT &&
556 (nd->nl_flags & (NLC_CREATE | NLC_RENAME_DST))
558 if (nd->nl_flags & NLC_NFS_RDONLY) {
561 error = naccess(&nch, nd->nl_flags | dflags,
565 if (error == 0 && wasdotordotdot &&
566 (nd->nl_flags & (NLC_CREATE | NLC_DELETE |
567 NLC_RENAME_SRC | NLC_RENAME_DST))) {
571 if (nd->nl_flags & NLC_CREATE)
573 else if (nd->nl_flags & NLC_DELETE)
574 error = (wasdotordotdot == 1) ? EINVAL : ENOTEMPTY;
581 * Early completion on error.
589 * If the element is a symlink and it is either not the last
590 * element or it is the last element and we are allowed to
591 * follow symlinks, resolve the symlink.
593 if ((nch.ncp->nc_flag & NCF_ISSYMLINK) &&
594 (*ptr || (nd->nl_flags & NLC_FOLLOW))
596 if (nd->nl_loopcnt++ >= MAXSYMLINKS) {
601 error = nreadsymlink(nd, &nch, &nlc);
607 * Concatenate trailing path elements onto the returned symlink.
608 * Note that if the path component (ptr) is not exhausted, it
609 * will being with a '/', so we do not have to add another one.
611 * The symlink may not be empty.
614 if (nlc.nlc_namelen == 0 || nlc.nlc_namelen + len >= MAXPATHLEN) {
615 error = nlc.nlc_namelen ? ENAMETOOLONG : ENOENT;
616 objcache_put(namei_oc, nlc.nlc_nameptr);
619 bcopy(ptr, nlc.nlc_nameptr + nlc.nlc_namelen, len + 1);
620 if (nd->nl_flags & NLC_HASBUF)
621 objcache_put(namei_oc, nd->nl_path);
622 nd->nl_path = nlc.nlc_nameptr;
623 nd->nl_flags |= NLC_HASBUF;
627 * Go back up to the top to resolve any initial '/'s in the
634 * If the element is a directory and we are crossing a mount point,
637 while ((nch.ncp->nc_flag & NCF_ISMOUNTPT) &&
638 (nd->nl_flags & NLC_NOCROSSMOUNT) == 0 &&
639 (mp = cache_findmount(&nch)) != NULL
644 cache_get(&mp->mnt_ncmountpt, &nch);
646 if (nch.ncp->nc_flag & NCF_UNRESOLVED) {
647 while (vfs_busy(mp, 0))
649 error = VFS_ROOT(mp, &tdp);
653 cache_setvp(&nch, tdp);
663 * Skip any slashes to get to the next element. If there
664 * are any slashes at all the current element must be a
665 * directory or, in the create case, intended to become a directory.
666 * If it isn't we break without incrementing ptr and fall through
667 * to the failure case below.
669 while (*ptr == '/') {
670 if ((nch.ncp->nc_flag & NCF_ISDIR) == 0 &&
671 !(nd->nl_flags & NLC_WILLBEDIR)
679 * Continuation case: additional elements and the current
680 * element is a directory.
682 if (*ptr && (nch.ncp->nc_flag & NCF_ISDIR)) {
683 cache_drop(&nd->nl_nch);
690 * Failure case: additional elements and the current element
700 * Successful lookup of last element.
702 * Check permissions if the target exists. If the target does not
703 * exist directory permissions were already tested in the early
704 * completion code above.
706 * nd->nl_flags will be adjusted on return with NLC_APPENDONLY
707 * if the file is marked append-only, and NLC_STICKY if the directory
708 * containing the file is sticky.
710 if (nch.ncp->nc_vp && (nd->nl_flags & NLC_ALLCHKS)) {
711 error = naccess(&nch, nd->nl_flags | dflags,
720 * Termination: no more elements.
722 * If NLC_REFDVP is set acquire a referenced parent dvp.
724 if (nd->nl_flags & NLC_REFDVP) {
725 error = cache_vref(&nd->nl_nch, nd->nl_cred, &nd->nl_dvp);
727 kprintf("NLC_REFDVP: Cannot ref dvp of %p\n", nch.ncp);
732 cache_drop(&nd->nl_nch);
734 nd->nl_flags |= NLC_NCPISLOCKED;
740 * NOTE: If NLC_CREATE was set the ncp may represent a negative hit
741 * (ncp->nc_error will be ENOENT), but we will still return an error
748 * Resolve a mount point's glue ncp. This ncp connects creates the illusion
749 * of continuity in the namecache tree by connecting the ncp related to the
750 * vnode under the mount to the ncp related to the mount's root vnode.
752 * If no error occured a locked, ref'd ncp is stored in *ncpp.
755 nlookup_mp(struct mount *mp, struct nchandle *nch)
761 cache_get(&mp->mnt_ncmountpt, nch);
762 if (nch->ncp->nc_flag & NCF_UNRESOLVED) {
763 while (vfs_busy(mp, 0))
765 error = VFS_ROOT(mp, &vp);
770 cache_setvp(nch, vp);
778 * Read the contents of a symlink, allocate a path buffer out of the
779 * namei_oc and initialize the supplied nlcomponent with the result.
781 * If an error occurs no buffer will be allocated or returned in the nlc.
784 nreadsymlink(struct nlookupdata *nd, struct nchandle *nch,
785 struct nlcomponent *nlc)
794 nlc->nlc_nameptr = NULL;
795 nlc->nlc_namelen = 0;
796 if (nch->ncp->nc_vp == NULL)
798 if ((error = cache_vget(nch, nd->nl_cred, LK_SHARED, &vp)) != 0)
800 cp = objcache_get(namei_oc, M_WAITOK);
802 aiov.iov_len = MAXPATHLEN;
803 auio.uio_iov = &aiov;
806 auio.uio_rw = UIO_READ;
807 auio.uio_segflg = UIO_SYSSPACE;
808 auio.uio_td = nd->nl_td;
809 auio.uio_resid = MAXPATHLEN - 1;
810 error = VOP_READLINK(vp, &auio, nd->nl_cred);
813 linklen = MAXPATHLEN - 1 - auio.uio_resid;
815 linklen = varsymreplace(cp, linklen, MAXPATHLEN - 1);
817 error = ENAMETOOLONG;
822 nlc->nlc_nameptr = cp;
823 nlc->nlc_namelen = linklen;
827 objcache_put(namei_oc, cp);
833 * Check access [XXX cache vattr!] [XXX quota]
835 * Generally check the NLC_* access bits. All specified bits must pass
836 * for this function to return 0.
838 * The file does not have to exist when checking NLC_CREATE or NLC_RENAME_DST
839 * access, otherwise it must exist. No error is returned in this case.
841 * The file must not exist if NLC_EXCL is specified.
843 * Directory permissions in general are tested for NLC_CREATE if the file
844 * does not exist, NLC_DELETE if the file does exist, and NLC_RENAME_DST
845 * whether the file exists or not.
847 * The directory sticky bit is tested for NLC_DELETE and NLC_RENAME_DST,
848 * the latter is only tested if the target exists.
850 * The passed ncp may or may not be locked. The caller should use a
851 * locked ncp on leaf lookups, especially for NLC_CREATE, NLC_RENAME_DST,
852 * NLC_DELETE, and NLC_EXCL checks.
855 naccess(struct nchandle *nch, int nflags, struct ucred *cred, int *nflagsp)
863 if (nch->ncp->nc_flag & NCF_UNRESOLVED) {
865 cache_resolve(nch, cred);
868 error = nch->ncp->nc_error;
871 * Directory permissions checks. Silently ignore ENOENT if these
872 * tests pass. It isn't an error.
874 if (nflags & (NLC_CREATE | NLC_DELETE | NLC_RENAME_SRC | NLC_RENAME_DST)) {
875 if (((nflags & NLC_CREATE) && nch->ncp->nc_vp == NULL) ||
876 ((nflags & NLC_DELETE) && nch->ncp->nc_vp != NULL) ||
877 ((nflags & NLC_RENAME_SRC) && nch->ncp->nc_vp != NULL) ||
878 (nflags & NLC_RENAME_DST)
880 if ((par.ncp = nch->ncp->nc_parent) == NULL) {
883 } else if (error == 0 || error == ENOENT) {
884 par.mount = nch->mount;
887 error = naccess(&par, NLC_WRITE, cred, NULL);
894 * NLC_EXCL check. Target file must not exist.
896 if (error == 0 && (nflags & NLC_EXCL) && nch->ncp->nc_vp != NULL)
900 * Get the vnode attributes so we can do the rest of our checks.
902 * NOTE: We only call naccess_va() if the target exists.
905 error = cache_vget(nch, cred, LK_SHARED, &vp);
906 if (error == ENOENT) {
908 * Silently zero-out ENOENT if creating or renaming
909 * (rename target). It isn't an error.
911 if (nflags & (NLC_CREATE | NLC_RENAME_DST))
913 } else if (error == 0) {
915 * Get the vnode attributes and check for illegal O_TRUNC
916 * requests and read-only mounts.
918 * NOTE: You can still open devices on read-only mounts for
921 * NOTE: creates/deletes/renames are handled by the NLC_WRITE
922 * check on the parent directory above.
924 * XXX cache the va in the namecache or in the vnode
926 error = VOP_GETATTR(vp, &va);
927 if (error == 0 && (nflags & NLC_TRUNCATE)) {
943 if (error == 0 && (nflags & NLC_WRITE) && vp->v_mount &&
944 (vp->v_mount->mnt_flag & MNT_RDONLY)
960 * Check permissions based on file attributes. The passed
961 * flags (*nflagsp) are modified with feedback based on
962 * special attributes and requirements.
966 * Adjust the returned (*nflagsp) if non-NULL.
969 if ((va.va_mode & VSVTX) && va.va_uid != cred->cr_uid)
970 *nflagsp |= NLC_STICKY;
971 if (va.va_flags & APPEND)
972 *nflagsp |= NLC_APPENDONLY;
973 if (va.va_flags & IMMUTABLE)
974 *nflagsp |= NLC_IMMUTABLE;
978 * Process general access.
980 error = naccess_va(&va, nflags, cred);
988 * Check the requested access against the given vattr using cred.
991 naccess_va(struct vattr *va, int nflags, struct ucred *cred)
997 * Test the immutable bit. Creations, deletions, renames (source
998 * or destination) are not allowed. chown/chmod/other is also not
999 * allowed but is handled by SETATTR. Hardlinks to the immutable
1002 * If the directory is set to immutable then creations, deletions,
1003 * renames (source or dest) and hardlinks to files within the directory
1004 * are not allowed, and regular files opened through the directory may
1005 * not be written to or truncated (unless a special device).
1007 * NOTE! New hardlinks to immutable files work but new hardlinks to
1008 * files, immutable or not, sitting inside an immutable directory are
1009 * not allowed. As always if the file is hardlinked via some other
1010 * path additional hardlinks may be possible even if the file is marked
1011 * immutable. The sysop needs to create a closure by checking the hard
1012 * link count. Once closure is achieved you are good, and security
1013 * scripts should check link counts anyway.
1015 * Writes and truncations are only allowed on special devices.
1017 if ((va->va_flags & IMMUTABLE) || (nflags & NLC_IMMUTABLE)) {
1018 if ((nflags & NLC_IMMUTABLE) && (nflags & NLC_HLINK))
1020 if (nflags & (NLC_CREATE | NLC_DELETE |
1021 NLC_RENAME_SRC | NLC_RENAME_DST)) {
1024 if (nflags & (NLC_WRITE | NLC_TRUNCATE)) {
1025 switch(va->va_type) {
1039 * Test the no-unlink and append-only bits for opens, rename targets,
1040 * and deletions. These bits are not tested for creations or
1043 * Unlike FreeBSD we allow a file with APPEND set to be renamed.
1044 * If you do not wish this you must also set NOUNLINK.
1046 * If the governing directory is marked APPEND-only it implies
1047 * NOUNLINK for all entries in the directory.
1049 if (((va->va_flags & NOUNLINK) || (nflags & NLC_APPENDONLY)) &&
1050 (nflags & (NLC_DELETE | NLC_RENAME_SRC | NLC_RENAME_DST))
1056 * A file marked append-only may not be deleted but can be renamed.
1058 if ((va->va_flags & APPEND) &&
1059 (nflags & (NLC_DELETE | NLC_RENAME_DST))
1065 * A file marked append-only which is opened for writing must also
1066 * be opened O_APPEND.
1068 if ((va->va_flags & APPEND) && (nflags & (NLC_OPEN | NLC_TRUNCATE))) {
1069 if (nflags & NLC_TRUNCATE)
1071 if ((nflags & (NLC_OPEN | NLC_WRITE)) == (NLC_OPEN | NLC_WRITE)) {
1072 if ((nflags & NLC_APPEND) == 0)
1078 * root gets universal access
1080 if (cred->cr_uid == 0)
1084 * Check owner perms.
1086 * If NLC_OWN is set the owner of the file is allowed no matter when
1087 * the owner-mode bits say (utimes).
1090 if (nflags & NLC_READ)
1092 if (nflags & NLC_WRITE)
1094 if (nflags & NLC_EXEC)
1097 if (cred->cr_uid == va->va_uid) {
1098 if ((nflags & NLC_OWN) == 0) {
1099 if ((vmode & va->va_mode) != vmode)
1106 * If NLC_STICKY is set only the owner may delete or rename a file.
1107 * This bit is typically set on /tmp.
1109 * Note that the NLC_READ/WRITE/EXEC bits are not typically set in
1110 * the specific delete or rename case. For deletions and renames we
1111 * usually just care about directory permissions, not file permissions.
1113 if ((nflags & NLC_STICKY) &&
1114 (nflags & (NLC_RENAME_SRC | NLC_RENAME_DST | NLC_DELETE))) {
1122 for (i = 0; i < cred->cr_ngroups; ++i) {
1123 if (va->va_gid == cred->cr_groups[i]) {
1124 if ((vmode & va->va_mode) != vmode)
1134 if ((vmode & va->va_mode) != vmode)