kernel - swapcache - Fix snocache and cache flags propagation, fix PG_NOTMETA
[dragonfly.git] / sys / kern / vfs_nlookup.c
CommitLineData
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1/*
2 * Copyright (c) 2004 The DragonFly Project. All rights reserved.
3 *
4 * This code is derived from software contributed to The DragonFly Project
5 * by Matthew Dillon <dillon@backplane.com>
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 *
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
16 * distribution.
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.
20 *
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
32 * SUCH DAMAGE.
33 *
c9aef211 34 * $DragonFly: src/sys/kern/vfs_nlookup.c,v 1.25 2008/07/19 04:43:33 dillon Exp $
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35 */
36/*
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.
43 *
44 * This greatly improves filesystem parallelism and is a huge simplification
45 * of the API verses the old vnode locking / namei scheme.
46 *
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
51 * these issues.
52 */
53
54#include "opt_ktrace.h"
55
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>
62#include <sys/proc.h>
63#include <sys/namei.h>
64#include <sys/nlookup.h>
65#include <sys/malloc.h>
21739618 66#include <sys/stat.h>
70aac194 67#include <sys/objcache.h>
1db695af 68#include <sys/file.h>
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69
70#ifdef KTRACE
71#include <sys/ktrace.h>
72#endif
73
e9b56058 74static int naccess(struct nchandle *nch, int vmode, struct ucred *cred,
aabd5ce8 75 int *stickyp);
e9b56058 76
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77/*
78 * Initialize a nlookup() structure, early error return for copyin faults
79 * or a degenerate empty string (which is not allowed).
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80 *
81 * The first process proc0's credentials are used if the calling thread
82 * is not associated with a process context.
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83 *
84 * MPSAFE
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85 */
86int
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87nlookup_init(struct nlookupdata *nd,
88 const char *path, enum uio_seg seg, int flags)
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89{
90 size_t pathlen;
91 struct proc *p;
92 thread_t td;
93 int error;
94
95 td = curthread;
96 p = td->td_proc;
97
98 /*
99 * note: the pathlen set by copy*str() includes the terminating \0.
100 */
101 bzero(nd, sizeof(struct nlookupdata));
70aac194 102 nd->nl_path = objcache_get(namei_oc, M_WAITOK);
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103 nd->nl_flags |= NLC_HASBUF;
104 if (seg == UIO_SYSSPACE)
105 error = copystr(path, nd->nl_path, MAXPATHLEN, &pathlen);
106 else
107 error = copyinstr(path, nd->nl_path, MAXPATHLEN, &pathlen);
108
109 /*
110 * Don't allow empty pathnames.
111 * POSIX.1 requirement: "" is not a vaild file name.
112 */
113 if (error == 0 && pathlen <= 1)
114 error = ENOENT;
115
116 if (error == 0) {
21739618 117 if (p && p->p_fd) {
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118 cache_copy(&p->p_fd->fd_ncdir, &nd->nl_nch);
119 cache_copy(&p->p_fd->fd_nrdir, &nd->nl_rootnch);
120 if (p->p_fd->fd_njdir.ncp)
121 cache_copy(&p->p_fd->fd_njdir, &nd->nl_jailnch);
21739618 122 nd->nl_cred = crhold(p->p_ucred);
690a3127 123 } else {
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124 cache_copy(&rootnch, &nd->nl_nch);
125 cache_copy(&nd->nl_nch, &nd->nl_rootnch);
126 cache_copy(&nd->nl_nch, &nd->nl_jailnch);
21739618 127 nd->nl_cred = crhold(proc0.p_ucred);
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128 }
129 nd->nl_td = td;
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130 nd->nl_flags |= flags;
131 } else {
132 nlookup_done(nd);
133 }
134 return(error);
135}
136
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137
138/*
139 * nlookup_init() for "at" family of syscalls.
140 *
141 * Works similarly to nlookup_init() but if path is relative and fd is not
142 * AT_FDCWD, path is interpreted relative to the directory pointed to by fd.
143 * In this case, the file entry pointed to by fd is ref'ed and returned in
144 * *fpp.
145 *
146 * If the call succeeds, nlookup_done_at() must be called to clean-up the nd
147 * and release the ref to the file entry.
148 */
149int
150nlookup_init_at(struct nlookupdata *nd, struct file **fpp, int fd,
151 const char *path, enum uio_seg seg, int flags)
152{
153 struct thread *td = curthread;
154 struct proc *p = td->td_proc;
155 struct file* fp;
156 struct vnode *vp;
157 int error;
158
159 *fpp = NULL;
160
161 if ((error = nlookup_init(nd, path, seg, flags)) != 0) {
162 return (error);
163 }
164
165 if (nd->nl_path[0] != '/' && fd != AT_FDCWD) {
166 if ((error = holdvnode(p->p_fd, fd, &fp)) != 0)
167 goto done;
168 vp = (struct vnode*)fp->f_data;
169 if (vp->v_type != VDIR || fp->f_nchandle.ncp == NULL) {
170 fdrop(fp);
171 fp = NULL;
172 error = ENOTDIR;
173 goto done;
174 }
175 cache_drop(&nd->nl_nch);
176 cache_copy(&fp->f_nchandle, &nd->nl_nch);
177 *fpp = fp;
178 }
179
180
181done:
182 if (error)
183 nlookup_done(nd);
184 return (error);
185
186}
187
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188/*
189 * This works similarly to nlookup_init() but does not assume a process
28623bf9 190 * context. rootnch is always chosen for the root directory and the cred
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191 * and starting directory are supplied in arguments.
192 */
193int
194nlookup_init_raw(struct nlookupdata *nd,
195 const char *path, enum uio_seg seg, int flags,
28623bf9 196 struct ucred *cred, struct nchandle *ncstart)
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197{
198 size_t pathlen;
199 thread_t td;
200 int error;
201
202 td = curthread;
203
204 bzero(nd, sizeof(struct nlookupdata));
70aac194 205 nd->nl_path = objcache_get(namei_oc, M_WAITOK);
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206 nd->nl_flags |= NLC_HASBUF;
207 if (seg == UIO_SYSSPACE)
208 error = copystr(path, nd->nl_path, MAXPATHLEN, &pathlen);
209 else
210 error = copyinstr(path, nd->nl_path, MAXPATHLEN, &pathlen);
211
212 /*
213 * Don't allow empty pathnames.
214 * POSIX.1 requirement: "" is not a vaild file name.
215 */
216 if (error == 0 && pathlen <= 1)
217 error = ENOENT;
218
219 if (error == 0) {
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220 cache_copy(ncstart, &nd->nl_nch);
221 cache_copy(&rootnch, &nd->nl_rootnch);
222 cache_copy(&rootnch, &nd->nl_jailnch);
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223 nd->nl_cred = crhold(cred);
224 nd->nl_td = td;
225 nd->nl_flags |= flags;
226 } else {
227 nlookup_done(nd);
228 }
229 return(error);
230}
231
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232/*
233 * Set a different credential; this credential will be used by future
234 * operations performed on nd.nl_open_vp and nlookupdata structure.
235 */
236void
237nlookup_set_cred(struct nlookupdata *nd, struct ucred *cred)
238{
239 KKASSERT(nd->nl_cred != NULL);
240
241 if (nd->nl_cred != cred) {
242 cred = crhold(cred);
243 crfree(nd->nl_cred);
244 nd->nl_cred = cred;
245 }
246}
247
690a3127 248/*
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249 * Cleanup a nlookupdata structure after we are through with it. This may
250 * be called on any nlookupdata structure initialized with nlookup_init().
251 * Calling nlookup_done() is mandatory in all cases except where nlookup_init()
252 * returns an error, even if as a consumer you believe you have taken all
253 * dynamic elements out of the nlookupdata structure.
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254 */
255void
256nlookup_done(struct nlookupdata *nd)
257{
28623bf9 258 if (nd->nl_nch.ncp) {
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259 if (nd->nl_flags & NLC_NCPISLOCKED) {
260 nd->nl_flags &= ~NLC_NCPISLOCKED;
28623bf9 261 cache_unlock(&nd->nl_nch);
21739618 262 }
2247fe02 263 cache_drop(&nd->nl_nch); /* NULL's out the nch */
690a3127 264 }
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265 if (nd->nl_rootnch.ncp)
266 cache_drop(&nd->nl_rootnch);
267 if (nd->nl_jailnch.ncp)
268 cache_drop(&nd->nl_jailnch);
690a3127 269 if ((nd->nl_flags & NLC_HASBUF) && nd->nl_path) {
70aac194 270 objcache_put(namei_oc, nd->nl_path);
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271 nd->nl_path = NULL;
272 }
273 if (nd->nl_cred) {
274 crfree(nd->nl_cred);
275 nd->nl_cred = NULL;
276 }
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277 if (nd->nl_open_vp) {
278 if (nd->nl_flags & NLC_LOCKVP) {
a11aaa81 279 vn_unlock(nd->nl_open_vp);
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280 nd->nl_flags &= ~NLC_LOCKVP;
281 }
87de5057 282 vn_close(nd->nl_open_vp, nd->nl_vp_fmode);
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283 nd->nl_open_vp = NULL;
284 }
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285 if (nd->nl_dvp) {
286 vrele(nd->nl_dvp);
287 nd->nl_dvp = NULL;
288 }
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289 nd->nl_flags = 0; /* clear remaining flags (just clear everything) */
290}
291
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292/*
293 * Works similarly to nlookup_done() when nd initialized with
294 * nlookup_init_at().
295 */
296void
297nlookup_done_at(struct nlookupdata *nd, struct file *fp)
298{
299 nlookup_done(nd);
300 if (fp != NULL)
301 fdrop(fp);
302}
303
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304void
305nlookup_zero(struct nlookupdata *nd)
306{
2247fe02 307 bzero(nd, sizeof(struct nlookupdata));
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308}
309
310/*
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311 * Simple all-in-one nlookup. Returns a locked namecache structure or NULL
312 * if an error occured.
313 *
314 * Note that the returned ncp is not checked for permissions, though VEXEC
315 * is checked on the directory path leading up to the result. The caller
316 * must call naccess() to check the permissions of the returned leaf.
690a3127 317 */
28623bf9 318struct nchandle
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319nlookup_simple(const char *str, enum uio_seg seg,
320 int niflags, int *error)
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321{
322 struct nlookupdata nd;
28623bf9 323 struct nchandle nch;
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324
325 *error = nlookup_init(&nd, str, seg, niflags);
326 if (*error == 0) {
21739618 327 if ((*error = nlookup(&nd)) == 0) {
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328 nch = nd.nl_nch; /* keep hold ref from structure */
329 cache_zero(&nd.nl_nch); /* and NULL out */
21739618 330 } else {
28623bf9 331 cache_zero(&nch);
21739618 332 }
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333 nlookup_done(&nd);
334 } else {
28623bf9 335 cache_zero(&nch);
690a3127 336 }
28623bf9 337 return(nch);
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338}
339
340/*
341 * Do a generic nlookup. Note that the passed nd is not nlookup_done()'d
342 * on return, even if an error occurs. If no error occurs the returned
28623bf9 343 * nl_nch is always referenced and locked, otherwise it may or may not be.
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344 *
345 * Intermediate directory elements, including the current directory, require
346 * execute (search) permission. nlookup does not examine the access
347 * permissions on the returned element.
fad57d0e 348 *
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349 * If NLC_CREATE is set the last directory must allow node creation,
350 * and an error code of 0 will be returned for a non-existant
351 * target (not ENOENT).
352 *
3a907475 353 * If NLC_RENAME_DST is set the last directory mut allow node deletion,
945b476a 354 * plus the sticky check is made, and an error code of 0 will be returned
3a907475 355 * for a non-existant target (not ENOENT).
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356 *
357 * If NLC_DELETE is set the last directory mut allow node deletion,
358 * plus the sticky check is made.
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359 *
360 * If NLC_REFDVP is set nd->nl_dvp will be set to the directory vnode
361 * of the returned entry. The vnode will be referenced, but not locked,
362 * and will be released by nlookup_done() along with everything else.
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363 */
364int
365nlookup(struct nlookupdata *nd)
366{
367 struct nlcomponent nlc;
28623bf9 368 struct nchandle nch;
3a907475 369 struct nchandle par;
f63911bf 370 struct nchandle nctmp;
28623bf9 371 struct mount *mp;
f4d4e93a 372 int wasdotordotdot;
690a3127 373 char *ptr;
fad57d0e 374 char *xptr;
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375 int error;
376 int len;
3a907475 377 int dflags;
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378
379#ifdef KTRACE
380 if (KTRPOINT(nd->nl_td, KTR_NAMEI))
9fb04d14 381 ktrnamei(nd->nl_td->td_lwp, nd->nl_path);
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382#endif
383 bzero(&nlc, sizeof(nlc));
384
385 /*
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386 * Setup for the loop. The current working namecache element is
387 * always at least referenced. We lock it as required, but always
388 * return a locked, resolved namecache entry.
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389 */
390 nd->nl_loopcnt = 0;
2247fe02 391 if (nd->nl_dvp) {
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392 vrele(nd->nl_dvp);
393 nd->nl_dvp = NULL;
394 }
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395 ptr = nd->nl_path;
396
397 /*
28623bf9 398 * Loop on the path components. At the top of the loop nd->nl_nch
524c845c 399 * is ref'd and unlocked and represents our current position.
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400 */
401 for (;;) {
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402 /*
403 * Make sure nl_nch is locked so we can access the vnode, resolution
404 * state, etc.
405 */
406 if ((nd->nl_flags & NLC_NCPISLOCKED) == 0) {
407 nd->nl_flags |= NLC_NCPISLOCKED;
408 cache_lock(&nd->nl_nch);
409 }
410
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411 /*
412 * Check if the root directory should replace the current
413 * directory. This is done at the start of a translation
414 * or after a symbolic link has been found. In other cases
415 * ptr will never be pointing at a '/'.
416 */
417 if (*ptr == '/') {
418 do {
419 ++ptr;
420 } while (*ptr == '/');
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421 cache_get(&nd->nl_rootnch, &nch);
422 cache_put(&nd->nl_nch);
423 nd->nl_nch = nch; /* remains locked */
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424
425 /*
426 * Fast-track termination. There is no parent directory of
427 * the root in the same mount from the point of view of
428 * the caller so return EPERM if NLC_REFDVP is specified.
429 * e.g. 'rmdir /' is not allowed.
430 */
21739618 431 if (*ptr == 0) {
2247fe02 432 if (nd->nl_flags & NLC_REFDVP)
5312fa43 433 error = EPERM;
2247fe02 434 else
5312fa43 435 error = 0;
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436 break;
437 }
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438 continue;
439 }
440
21739618 441 /*
28623bf9 442 * Check directory search permissions.
21739618 443 */
3a907475 444 dflags = 0;
aabd5ce8 445 error = naccess(&nd->nl_nch, NLC_EXEC, nd->nl_cred, &dflags);
e9b56058 446 if (error)
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447 break;
448
690a3127 449 /*
d7c75c7a
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450 * Extract the path component. Path components are limited to
451 * 255 characters.
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452 */
453 nlc.nlc_nameptr = ptr;
454 while (*ptr && *ptr != '/')
455 ++ptr;
456 nlc.nlc_namelen = ptr - nlc.nlc_nameptr;
d7c75c7a
MD
457 if (nlc.nlc_namelen >= 256) {
458 error = ENAMETOOLONG;
459 break;
460 }
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461
462 /*
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463 * Lookup the path component in the cache, creating an unresolved
464 * entry if necessary. We have to handle "." and ".." as special
465 * cases.
466 *
467 * When handling ".." we have to detect a traversal back through a
28623bf9 468 * mount point. If we are at the root, ".." just returns the root.
524c845c 469 *
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470 * When handling "." or ".." we also have to recalculate dflags
471 * since our dflags will be for some sub-directory instead of the
472 * parent dir.
473 *
28623bf9 474 * This subsection returns a locked, refd 'nch' unless it errors out.
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475 * The namecache topology is not allowed to be disconnected, so
476 * encountering a NULL parent will generate EINVAL. This typically
477 * occurs when a directory is removed out from under a process.
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MD
478 */
479 if (nlc.nlc_namelen == 1 && nlc.nlc_nameptr[0] == '.') {
28623bf9 480 cache_get(&nd->nl_nch, &nch);
f4d4e93a 481 wasdotordotdot = 1;
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MD
482 } else if (nlc.nlc_namelen == 2 &&
483 nlc.nlc_nameptr[0] == '.' && nlc.nlc_nameptr[1] == '.') {
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484 if (nd->nl_nch.mount == nd->nl_rootnch.mount &&
485 nd->nl_nch.ncp == nd->nl_rootnch.ncp
486 ) {
487 /*
488 * ".." at the root returns the root
489 */
490 cache_get(&nd->nl_nch, &nch);
21739618 491 } else {
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492 /*
493 * Locate the parent ncp. If we are at the root of a
494 * filesystem mount we have to skip to the mounted-on
495 * point in the underlying filesystem.
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496 *
497 * Expect the parent to always be good since the
498 * mountpoint doesn't go away. XXX hack. cache_get()
499 * requires the ncp to already have a ref as a safety.
28623bf9 500 */
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501 nctmp = nd->nl_nch;
502 while (nctmp.ncp == nctmp.mount->mnt_ncmountpt.ncp)
503 nctmp = nctmp.mount->mnt_ncmounton;
504 nctmp.ncp = nctmp.ncp->nc_parent;
505 KKASSERT(nctmp.ncp != NULL);
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506 cache_hold(&nctmp);
507 cache_get(&nctmp, &nch);
f63911bf 508 cache_drop(&nctmp); /* NOTE: zero's nctmp */
21739618 509 }
d7c75c7a 510 wasdotordotdot = 2;
21739618 511 } else {
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512 /*
513 * Must unlock nl_nch when traversing down the path.
514 */
515 cache_unlock(&nd->nl_nch);
516 nd->nl_flags &= ~NLC_NCPISLOCKED;
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517 nch = cache_nlookup(&nd->nl_nch, &nlc);
518 while ((error = cache_resolve(&nch, nd->nl_cred)) == EAGAIN) {
6ea70f76 519 kprintf("[diagnostic] nlookup: relookup %*.*s\n",
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MD
520 nch.ncp->nc_nlen, nch.ncp->nc_nlen, nch.ncp->nc_name);
521 cache_put(&nch);
522 nch = cache_nlookup(&nd->nl_nch, &nlc);
8e005a45 523 }
f4d4e93a 524 wasdotordotdot = 0;
21739618 525 }
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526
527 /*
528 * If the last component was "." or ".." our dflags no longer
529 * represents the parent directory and we have to explicitly
530 * look it up.
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531 *
532 * Expect the parent to be good since nch is locked.
3a907475
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533 */
534 if (wasdotordotdot && error == 0) {
535 dflags = 0;
536 if ((par.ncp = nch.ncp->nc_parent) != NULL) {
537 par.mount = nch.mount;
538 cache_hold(&par);
2247fe02 539 cache_lock(&par);
aabd5ce8 540 error = naccess(&par, 0, nd->nl_cred, &dflags);
2247fe02 541 cache_put(&par);
3a907475
MD
542 }
543 }
2247fe02
MD
544 if (nd->nl_flags & NLC_NCPISLOCKED) {
545 cache_unlock(&nd->nl_nch);
546 nd->nl_flags &= ~NLC_NCPISLOCKED;
547 }
3a907475 548
524c845c 549 /*
2247fe02
MD
550 * [end of subsection]
551 *
552 * nch is locked and referenced.
553 * nd->nl_nch is unlocked and referenced.
554 *
555 * nl_nch must be unlocked or we could chain lock to the root
556 * if a resolve gets stuck (e.g. in NFS).
524c845c 557 */
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558
559 /*
560 * Resolve the namespace if necessary. The ncp returned by
561 * cache_nlookup() is referenced and locked.
8e005a45
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562 *
563 * XXX neither '.' nor '..' should return EAGAIN since they were
564 * previously resolved and thus cannot be newly created ncp's.
690a3127 565 */
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566 if (nch.ncp->nc_flag & NCF_UNRESOLVED) {
567 error = cache_resolve(&nch, nd->nl_cred);
8e005a45 568 KKASSERT(error != EAGAIN);
690a3127 569 } else {
28623bf9 570 error = nch.ncp->nc_error;
690a3127 571 }
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572
573 /*
fad57d0e 574 * Early completion. ENOENT is not an error if this is the last
945b476a
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575 * component and NLC_CREATE or NLC_RENAME (rename target) was
576 * requested. Note that ncp->nc_error is left as ENOENT in that
577 * case, which we check later on.
578 *
f4d4e93a 579 * Also handle invalid '.' or '..' components terminating a path
945b476a
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580 * for a create/rename/delete. The standard requires this and pax
581 * pretty stupidly depends on it.
fad57d0e
MD
582 */
583 for (xptr = ptr; *xptr == '/'; ++xptr)
584 ;
f4d4e93a 585 if (*xptr == 0) {
3a907475
MD
586 if (error == ENOENT &&
587 (nd->nl_flags & (NLC_CREATE | NLC_RENAME_DST))
588 ) {
589 if (nd->nl_flags & NLC_NFS_RDONLY) {
c9aef211 590 error = EROFS;
3a907475
MD
591 } else {
592 error = naccess(&nch, nd->nl_flags | dflags,
aabd5ce8 593 nd->nl_cred, NULL);
3a907475 594 }
c9aef211 595 }
945b476a 596 if (error == 0 && wasdotordotdot &&
3a907475
MD
597 (nd->nl_flags & (NLC_CREATE | NLC_DELETE |
598 NLC_RENAME_SRC | NLC_RENAME_DST))) {
d7c75c7a
MD
599 /*
600 * POSIX junk
601 */
602 if (nd->nl_flags & NLC_CREATE)
603 error = EEXIST;
604 else if (nd->nl_flags & NLC_DELETE)
605 error = (wasdotordotdot == 1) ? EINVAL : ENOTEMPTY;
606 else
607 error = EINVAL;
945b476a 608 }
fad57d0e
MD
609 }
610
611 /*
612 * Early completion on error.
21739618 613 */
690a3127 614 if (error) {
28623bf9 615 cache_put(&nch);
690a3127
MD
616 break;
617 }
618
619 /*
620 * If the element is a symlink and it is either not the last
621 * element or it is the last element and we are allowed to
622 * follow symlinks, resolve the symlink.
623 */
28623bf9 624 if ((nch.ncp->nc_flag & NCF_ISSYMLINK) &&
690a3127
MD
625 (*ptr || (nd->nl_flags & NLC_FOLLOW))
626 ) {
627 if (nd->nl_loopcnt++ >= MAXSYMLINKS) {
21739618 628 error = ELOOP;
28623bf9 629 cache_put(&nch);
690a3127
MD
630 break;
631 }
28623bf9
MD
632 error = nreadsymlink(nd, &nch, &nlc);
633 cache_put(&nch);
21739618
MD
634 if (error)
635 break;
690a3127
MD
636
637 /*
638 * Concatenate trailing path elements onto the returned symlink.
639 * Note that if the path component (ptr) is not exhausted, it
640 * will being with a '/', so we do not have to add another one.
641 *
642 * The symlink may not be empty.
643 */
644 len = strlen(ptr);
645 if (nlc.nlc_namelen == 0 || nlc.nlc_namelen + len >= MAXPATHLEN) {
646 error = nlc.nlc_namelen ? ENAMETOOLONG : ENOENT;
70aac194 647 objcache_put(namei_oc, nlc.nlc_nameptr);
690a3127
MD
648 break;
649 }
650 bcopy(ptr, nlc.nlc_nameptr + nlc.nlc_namelen, len + 1);
651 if (nd->nl_flags & NLC_HASBUF)
70aac194 652 objcache_put(namei_oc, nd->nl_path);
690a3127
MD
653 nd->nl_path = nlc.nlc_nameptr;
654 nd->nl_flags |= NLC_HASBUF;
655 ptr = nd->nl_path;
656
657 /*
658 * Go back up to the top to resolve any initial '/'s in the
659 * symlink.
660 */
661 continue;
662 }
663
21739618
MD
664 /*
665 * If the element is a directory and we are crossing a mount point,
28623bf9 666 * Locate the mount.
21739618 667 */
28623bf9
MD
668 while ((nch.ncp->nc_flag & NCF_ISMOUNTPT) &&
669 (nd->nl_flags & NLC_NOCROSSMOUNT) == 0 &&
670 (mp = cache_findmount(&nch)) != NULL
21739618 671 ) {
21739618
MD
672 struct vnode *tdp;
673
28623bf9
MD
674 cache_put(&nch);
675 cache_get(&mp->mnt_ncmountpt, &nch);
21739618 676
28623bf9 677 if (nch.ncp->nc_flag & NCF_UNRESOLVED) {
f9642f56 678 while (vfs_busy(mp, 0))
21739618
MD
679 ;
680 error = VFS_ROOT(mp, &tdp);
f9642f56 681 vfs_unbusy(mp);
524c845c 682 if (error)
21739618 683 break;
28623bf9 684 cache_setvp(&nch, tdp);
21739618
MD
685 vput(tdp);
686 }
687 }
688 if (error) {
28623bf9 689 cache_put(&nch);
21739618
MD
690 break;
691 }
692
690a3127
MD
693 /*
694 * Skip any slashes to get to the next element. If there
695 * are any slashes at all the current element must be a
fad57d0e
MD
696 * directory or, in the create case, intended to become a directory.
697 * If it isn't we break without incrementing ptr and fall through
698 * to the failure case below.
690a3127
MD
699 */
700 while (*ptr == '/') {
28623bf9 701 if ((nch.ncp->nc_flag & NCF_ISDIR) == 0 &&
fad57d0e
MD
702 !(nd->nl_flags & NLC_WILLBEDIR)
703 ) {
690a3127 704 break;
fad57d0e 705 }
690a3127
MD
706 ++ptr;
707 }
708
709 /*
710 * Continuation case: additional elements and the current
711 * element is a directory.
712 */
28623bf9
MD
713 if (*ptr && (nch.ncp->nc_flag & NCF_ISDIR)) {
714 cache_drop(&nd->nl_nch);
715 cache_unlock(&nch);
2247fe02 716 KKASSERT((nd->nl_flags & NLC_NCPISLOCKED) == 0);
28623bf9 717 nd->nl_nch = nch;
690a3127
MD
718 continue;
719 }
720
721 /*
722 * Failure case: additional elements and the current element
723 * is not a directory
724 */
725 if (*ptr) {
28623bf9 726 cache_put(&nch);
690a3127
MD
727 error = ENOTDIR;
728 break;
729 }
730
fad57d0e
MD
731 /*
732 * Successful lookup of last element.
733 *
3a907475
MD
734 * Check permissions if the target exists. If the target does not
735 * exist directory permissions were already tested in the early
736 * completion code above.
945b476a 737 *
3a907475
MD
738 * nd->nl_flags will be adjusted on return with NLC_APPENDONLY
739 * if the file is marked append-only, and NLC_STICKY if the directory
740 * containing the file is sticky.
fad57d0e 741 */
3a907475
MD
742 if (nch.ncp->nc_vp && (nd->nl_flags & NLC_ALLCHKS)) {
743 error = naccess(&nch, nd->nl_flags | dflags,
aabd5ce8 744 nd->nl_cred, NULL);
945b476a 745 if (error) {
28623bf9 746 cache_put(&nch);
fad57d0e
MD
747 break;
748 }
749 }
750
690a3127 751 /*
3a907475 752 * Termination: no more elements.
5312fa43
MD
753 *
754 * If NLC_REFDVP is set acquire a referenced parent dvp.
690a3127 755 */
5312fa43 756 if (nd->nl_flags & NLC_REFDVP) {
2247fe02 757 cache_lock(&nd->nl_nch);
5312fa43 758 error = cache_vref(&nd->nl_nch, nd->nl_cred, &nd->nl_dvp);
2247fe02 759 cache_unlock(&nd->nl_nch);
5312fa43
MD
760 if (error) {
761 kprintf("NLC_REFDVP: Cannot ref dvp of %p\n", nch.ncp);
762 cache_put(&nch);
763 break;
764 }
765 }
28623bf9
MD
766 cache_drop(&nd->nl_nch);
767 nd->nl_nch = nch;
690a3127
MD
768 nd->nl_flags |= NLC_NCPISLOCKED;
769 error = 0;
770 break;
771 }
3a907475
MD
772
773 /*
774 * NOTE: If NLC_CREATE was set the ncp may represent a negative hit
775 * (ncp->nc_error will be ENOENT), but we will still return an error
776 * code of 0.
777 */
690a3127
MD
778 return(error);
779}
780
21739618
MD
781/*
782 * Resolve a mount point's glue ncp. This ncp connects creates the illusion
783 * of continuity in the namecache tree by connecting the ncp related to the
784 * vnode under the mount to the ncp related to the mount's root vnode.
785 *
786 * If no error occured a locked, ref'd ncp is stored in *ncpp.
787 */
788int
28623bf9 789nlookup_mp(struct mount *mp, struct nchandle *nch)
21739618 790{
21739618
MD
791 struct vnode *vp;
792 int error;
793
794 error = 0;
28623bf9
MD
795 cache_get(&mp->mnt_ncmountpt, nch);
796 if (nch->ncp->nc_flag & NCF_UNRESOLVED) {
f9642f56 797 while (vfs_busy(mp, 0))
21739618
MD
798 ;
799 error = VFS_ROOT(mp, &vp);
f9642f56 800 vfs_unbusy(mp);
21739618 801 if (error) {
28623bf9 802 cache_put(nch);
21739618 803 } else {
28623bf9 804 cache_setvp(nch, vp);
21739618
MD
805 vput(vp);
806 }
807 }
21739618
MD
808 return(error);
809}
810
690a3127
MD
811/*
812 * Read the contents of a symlink, allocate a path buffer out of the
70aac194 813 * namei_oc and initialize the supplied nlcomponent with the result.
690a3127
MD
814 *
815 * If an error occurs no buffer will be allocated or returned in the nlc.
816 */
817int
28623bf9 818nreadsymlink(struct nlookupdata *nd, struct nchandle *nch,
690a3127
MD
819 struct nlcomponent *nlc)
820{
21739618 821 struct vnode *vp;
690a3127
MD
822 struct iovec aiov;
823 struct uio auio;
824 int linklen;
825 int error;
826 char *cp;
827
828 nlc->nlc_nameptr = NULL;
829 nlc->nlc_namelen = 0;
28623bf9 830 if (nch->ncp->nc_vp == NULL)
690a3127 831 return(ENOENT);
28623bf9 832 if ((error = cache_vget(nch, nd->nl_cred, LK_SHARED, &vp)) != 0)
690a3127 833 return(error);
70aac194 834 cp = objcache_get(namei_oc, M_WAITOK);
690a3127
MD
835 aiov.iov_base = cp;
836 aiov.iov_len = MAXPATHLEN;
837 auio.uio_iov = &aiov;
838 auio.uio_iovcnt = 1;
839 auio.uio_offset = 0;
840 auio.uio_rw = UIO_READ;
841 auio.uio_segflg = UIO_SYSSPACE;
842 auio.uio_td = nd->nl_td;
843 auio.uio_resid = MAXPATHLEN - 1;
21739618 844 error = VOP_READLINK(vp, &auio, nd->nl_cred);
690a3127
MD
845 if (error)
846 goto fail;
21739618 847 linklen = MAXPATHLEN - 1 - auio.uio_resid;
690a3127
MD
848 if (varsym_enable) {
849 linklen = varsymreplace(cp, linklen, MAXPATHLEN - 1);
850 if (linklen < 0) {
851 error = ENAMETOOLONG;
852 goto fail;
853 }
854 }
855 cp[linklen] = 0;
856 nlc->nlc_nameptr = cp;
857 nlc->nlc_namelen = linklen;
21739618 858 vput(vp);
690a3127
MD
859 return(0);
860fail:
70aac194 861 objcache_put(namei_oc, cp);
21739618 862 vput(vp);
690a3127
MD
863 return(error);
864}
865
21739618
MD
866/*
867 * Check access [XXX cache vattr!] [XXX quota]
868 *
3a907475
MD
869 * Generally check the NLC_* access bits. All specified bits must pass
870 * for this function to return 0.
21739618 871 *
3a907475
MD
872 * The file does not have to exist when checking NLC_CREATE or NLC_RENAME_DST
873 * access, otherwise it must exist. No error is returned in this case.
945b476a 874 *
3a907475 875 * The file must not exist if NLC_EXCL is specified.
21739618 876 *
3a907475
MD
877 * Directory permissions in general are tested for NLC_CREATE if the file
878 * does not exist, NLC_DELETE if the file does exist, and NLC_RENAME_DST
879 * whether the file exists or not.
21739618 880 *
3a907475
MD
881 * The directory sticky bit is tested for NLC_DELETE and NLC_RENAME_DST,
882 * the latter is only tested if the target exists.
dae8d54f 883 *
2247fe02 884 * The passed ncp must be referenced and locked.
21739618
MD
885 */
886int
aabd5ce8 887naccess(struct nchandle *nch, int nflags, struct ucred *cred, int *nflagsp)
21739618
MD
888{
889 struct vnode *vp;
890 struct vattr va;
aabd5ce8 891 struct namecache *ncp;
21739618 892 int error;
e9b56058 893 int cflags;
21739618 894
2247fe02 895 ASSERT_NCH_LOCKED(nch);
aabd5ce8
MD
896 ncp = nch->ncp;
897 if (ncp->nc_flag & NCF_UNRESOLVED) {
28623bf9 898 cache_resolve(nch, cred);
aabd5ce8 899 ncp = nch->ncp;
21739618 900 }
aabd5ce8 901 error = ncp->nc_error;
dae8d54f 902
945b476a 903 /*
3a907475
MD
904 * Directory permissions checks. Silently ignore ENOENT if these
905 * tests pass. It isn't an error.
2247fe02 906 *
aabd5ce8
MD
907 * We can safely resolve ncp->nc_parent because ncp is currently
908 * locked.
945b476a 909 */
3a907475 910 if (nflags & (NLC_CREATE | NLC_DELETE | NLC_RENAME_SRC | NLC_RENAME_DST)) {
aabd5ce8
MD
911 if (((nflags & NLC_CREATE) && ncp->nc_vp == NULL) ||
912 ((nflags & NLC_DELETE) && ncp->nc_vp != NULL) ||
913 ((nflags & NLC_RENAME_SRC) && ncp->nc_vp != NULL) ||
3a907475 914 (nflags & NLC_RENAME_DST)
21739618 915 ) {
f63911bf
MD
916 struct nchandle par;
917
aabd5ce8 918 if ((par.ncp = ncp->nc_parent) == NULL) {
8e005a45 919 if (error != EAGAIN)
fad57d0e 920 error = EINVAL;
3a907475 921 } else if (error == 0 || error == ENOENT) {
28623bf9 922 par.mount = nch->mount;
2247fe02
MD
923 cache_hold(&par);
924 cache_lock(&par);
aabd5ce8 925 error = naccess(&par, NLC_WRITE, cred, NULL);
2247fe02 926 cache_put(&par);
8e005a45 927 }
21739618 928 }
21739618 929 }
3a907475
MD
930
931 /*
932 * NLC_EXCL check. Target file must not exist.
933 */
aabd5ce8 934 if (error == 0 && (nflags & NLC_EXCL) && ncp->nc_vp != NULL)
3a907475
MD
935 error = EEXIST;
936
937 /*
938 * Get the vnode attributes so we can do the rest of our checks.
939 *
940 * NOTE: We only call naccess_va() if the target exists.
941 */
21739618 942 if (error == 0) {
28623bf9 943 error = cache_vget(nch, cred, LK_SHARED, &vp);
21739618 944 if (error == ENOENT) {
3a907475
MD
945 /*
946 * Silently zero-out ENOENT if creating or renaming
947 * (rename target). It isn't an error.
948 */
949 if (nflags & (NLC_CREATE | NLC_RENAME_DST))
21739618
MD
950 error = 0;
951 } else if (error == 0) {
3a907475
MD
952 /*
953 * Get the vnode attributes and check for illegal O_TRUNC
954 * requests and read-only mounts.
955 *
956 * NOTE: You can still open devices on read-only mounts for
957 * writing.
958 *
959 * NOTE: creates/deletes/renames are handled by the NLC_WRITE
960 * check on the parent directory above.
961 *
962 * XXX cache the va in the namecache or in the vnode
963 */
964 error = VOP_GETATTR(vp, &va);
965 if (error == 0 && (nflags & NLC_TRUNCATE)) {
966 switch(va.va_type) {
967 case VREG:
968 case VDATABASE:
969 case VCHR:
970 case VBLK:
c9c08c19 971 case VFIFO:
3a907475 972 break;
d7c75c7a
MD
973 case VDIR:
974 error = EISDIR;
975 break;
3a907475
MD
976 default:
977 error = EINVAL;
978 break;
979 }
980 }
981 if (error == 0 && (nflags & NLC_WRITE) && vp->v_mount &&
982 (vp->v_mount->mnt_flag & MNT_RDONLY)
983 ) {
984 switch(va.va_type) {
985 case VDIR:
986 case VLNK:
987 case VREG:
988 case VDATABASE:
989 error = EROFS;
990 break;
991 default:
992 break;
21739618
MD
993 }
994 }
995 vput(vp);
dae8d54f 996
3a907475
MD
997 /*
998 * Check permissions based on file attributes. The passed
999 * flags (*nflagsp) are modified with feedback based on
1000 * special attributes and requirements.
1001 */
dae8d54f
MD
1002 if (error == 0) {
1003 /*
3a907475 1004 * Adjust the returned (*nflagsp) if non-NULL.
dae8d54f 1005 */
3a907475
MD
1006 if (nflagsp) {
1007 if ((va.va_mode & VSVTX) && va.va_uid != cred->cr_uid)
1008 *nflagsp |= NLC_STICKY;
1009 if (va.va_flags & APPEND)
1010 *nflagsp |= NLC_APPENDONLY;
1011 if (va.va_flags & IMMUTABLE)
1012 *nflagsp |= NLC_IMMUTABLE;
1013 }
dae8d54f 1014
e9b56058
MD
1015 /*
1016 * Track swapcache management flags in the namecache.
aabd5ce8
MD
1017 *
1018 * Calculate the flags based on the current vattr info
1019 * and recalculate the inherited flags from the parent
1020 * (the original cache linkage may have occurred without
1021 * getattrs and thus have stale flags).
e9b56058 1022 */
aabd5ce8 1023 cflags = 0;
e9b56058 1024 if (va.va_flags & SF_NOCACHE)
aabd5ce8 1025 cflags |= NCF_SF_NOCACHE;
e9b56058 1026 if (va.va_flags & UF_CACHE)
aabd5ce8
MD
1027 cflags |= NCF_UF_CACHE;
1028 if (ncp->nc_parent) {
1029 if (ncp->nc_parent->nc_flag &
1030 (NCF_SF_NOCACHE | NCF_SF_PNOCACHE)) {
1031 cflags |= NCF_SF_PNOCACHE;
1032 }
1033 if (ncp->nc_parent->nc_flag &
1034 (NCF_UF_CACHE | NCF_UF_PCACHE)) {
1035 cflags |= NCF_UF_PCACHE;
1036 }
1037 }
1038 ncp->nc_flag &= ~(NCF_SF_NOCACHE | NCF_UF_CACHE |
1039 NCF_SF_PNOCACHE | NCF_UF_PCACHE);
1040 ncp->nc_flag |= cflags;
e9b56058 1041
dae8d54f
MD
1042 /*
1043 * Process general access.
1044 */
3a907475 1045 error = naccess_va(&va, nflags, cred);
dae8d54f 1046 }
21739618
MD
1047 }
1048 }
1049 return(error);
1050}
1051
1052/*
1053 * Check the requested access against the given vattr using cred.
1054 */
1055int
3a907475 1056naccess_va(struct vattr *va, int nflags, struct ucred *cred)
21739618
MD
1057{
1058 int i;
3a907475 1059 int vmode;
21739618
MD
1060
1061 /*
3a907475
MD
1062 * Test the immutable bit. Creations, deletions, renames (source
1063 * or destination) are not allowed. chown/chmod/other is also not
1064 * allowed but is handled by SETATTR. Hardlinks to the immutable
1065 * file are allowed.
1066 *
1067 * If the directory is set to immutable then creations, deletions,
1068 * renames (source or dest) and hardlinks to files within the directory
1069 * are not allowed, and regular files opened through the directory may
1070 * not be written to or truncated (unless a special device).
945b476a 1071 *
3a907475
MD
1072 * NOTE! New hardlinks to immutable files work but new hardlinks to
1073 * files, immutable or not, sitting inside an immutable directory are
1074 * not allowed. As always if the file is hardlinked via some other
1075 * path additional hardlinks may be possible even if the file is marked
1076 * immutable. The sysop needs to create a closure by checking the hard
1077 * link count. Once closure is achieved you are good, and security
1078 * scripts should check link counts anyway.
1079 *
1080 * Writes and truncations are only allowed on special devices.
21739618 1081 */
3a907475
MD
1082 if ((va->va_flags & IMMUTABLE) || (nflags & NLC_IMMUTABLE)) {
1083 if ((nflags & NLC_IMMUTABLE) && (nflags & NLC_HLINK))
1084 return (EPERM);
1085 if (nflags & (NLC_CREATE | NLC_DELETE |
1086 NLC_RENAME_SRC | NLC_RENAME_DST)) {
1087 return (EPERM);
1088 }
1089 if (nflags & (NLC_WRITE | NLC_TRUNCATE)) {
1090 switch(va->va_type) {
1091 case VDIR:
d7c75c7a 1092 return (EISDIR);
3a907475
MD
1093 case VLNK:
1094 case VREG:
1095 case VDATABASE:
1096 return (EPERM);
1097 default:
1098 break;
1099 }
1100 }
1101 }
1102
1103 /*
1104 * Test the no-unlink and append-only bits for opens, rename targets,
1105 * and deletions. These bits are not tested for creations or
1106 * rename sources.
1107 *
1108 * Unlike FreeBSD we allow a file with APPEND set to be renamed.
1109 * If you do not wish this you must also set NOUNLINK.
1110 *
1111 * If the governing directory is marked APPEND-only it implies
1112 * NOUNLINK for all entries in the directory.
1113 */
1114 if (((va->va_flags & NOUNLINK) || (nflags & NLC_APPENDONLY)) &&
1115 (nflags & (NLC_DELETE | NLC_RENAME_SRC | NLC_RENAME_DST))
1116 ) {
1117 return (EPERM);
1118 }
1119
1120 /*
1121 * A file marked append-only may not be deleted but can be renamed.
1122 */
1123 if ((va->va_flags & APPEND) &&
1124 (nflags & (NLC_DELETE | NLC_RENAME_DST))
1125 ) {
1126 return (EPERM);
1127 }
1128
1129 /*
1130 * A file marked append-only which is opened for writing must also
1131 * be opened O_APPEND.
1132 */
1133 if ((va->va_flags & APPEND) && (nflags & (NLC_OPEN | NLC_TRUNCATE))) {
1134 if (nflags & NLC_TRUNCATE)
1135 return (EPERM);
1136 if ((nflags & (NLC_OPEN | NLC_WRITE)) == (NLC_OPEN | NLC_WRITE)) {
1137 if ((nflags & NLC_APPEND) == 0)
21739618
MD
1138 return (EPERM);
1139 }
1140 }
1141
1142 /*
1143 * root gets universal access
1144 */
1145 if (cred->cr_uid == 0)
1146 return(0);
1147
1148 /*
dae8d54f
MD
1149 * Check owner perms.
1150 *
3a907475 1151 * If NLC_OWN is set the owner of the file is allowed no matter when
dae8d54f 1152 * the owner-mode bits say (utimes).
21739618 1153 */
3a907475
MD
1154 vmode = 0;
1155 if (nflags & NLC_READ)
1156 vmode |= S_IRUSR;
1157 if (nflags & NLC_WRITE)
1158 vmode |= S_IWUSR;
1159 if (nflags & NLC_EXEC)
1160 vmode |= S_IXUSR;
1161
21739618 1162 if (cred->cr_uid == va->va_uid) {
3a907475 1163 if ((nflags & NLC_OWN) == 0) {
ee89633d
MD
1164 if ((vmode & va->va_mode) != vmode)
1165 return(EACCES);
1166 }
21739618
MD
1167 return(0);
1168 }
dae8d54f
MD
1169
1170 /*
3a907475
MD
1171 * If NLC_STICKY is set only the owner may delete or rename a file.
1172 * This bit is typically set on /tmp.
dae8d54f 1173 *
3a907475
MD
1174 * Note that the NLC_READ/WRITE/EXEC bits are not typically set in
1175 * the specific delete or rename case. For deletions and renames we
1176 * usually just care about directory permissions, not file permissions.
dae8d54f 1177 */
3a907475
MD
1178 if ((nflags & NLC_STICKY) &&
1179 (nflags & (NLC_RENAME_SRC | NLC_RENAME_DST | NLC_DELETE))) {
dae8d54f 1180 return(EACCES);
3a907475 1181 }
dae8d54f
MD
1182
1183 /*
1184 * Check group perms
1185 */
21739618
MD
1186 vmode >>= 3;
1187 for (i = 0; i < cred->cr_ngroups; ++i) {
1188 if (va->va_gid == cred->cr_groups[i]) {
1189 if ((vmode & va->va_mode) != vmode)
1190 return(EACCES);
1191 return(0);
1192 }
1193 }
1194
dae8d54f
MD
1195 /*
1196 * Check world perms
1197 */
21739618
MD
1198 vmode >>= 3;
1199 if ((vmode & va->va_mode) != vmode)
1200 return(EACCES);
1201 return(0);
1202}
1203