1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * NFS server file handle treatment.
4 *
5 * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
6 * Portions Copyright (C) 1999 G. Allen Morris III <gam3@acm.org>
7 * Extensive rewrite by Neil Brown <neilb@cse.unsw.edu.au> Southern-Spring 1999
8 * ... and again Southern-Winter 2001 to support export_operations
9 */
10
11 #include <linux/exportfs.h>
12
13 #include <linux/sunrpc/svcauth_gss.h>
14 #include "nfsd.h"
15 #include "vfs.h"
16 #include "auth.h"
17 #include "trace.h"
18
19 #define NFSDDBG_FACILITY NFSDDBG_FH
20
21
22 /*
23 * our acceptability function.
24 * if NOSUBTREECHECK, accept anything
25 * if not, require that we can walk up to exp->ex_dentry
26 * doing some checks on the 'x' bits
27 */
nfsd_acceptable(void * expv,struct dentry * dentry)28 static int nfsd_acceptable(void *expv, struct dentry *dentry)
29 {
30 struct svc_export *exp = expv;
31 int rv;
32 struct dentry *tdentry;
33 struct dentry *parent;
34
35 if (exp->ex_flags & NFSEXP_NOSUBTREECHECK)
36 return 1;
37
38 tdentry = dget(dentry);
39 while (tdentry != exp->ex_path.dentry && !IS_ROOT(tdentry)) {
40 /* make sure parents give x permission to user */
41 int err;
42 parent = dget_parent(tdentry);
43 err = inode_permission(&nop_mnt_idmap,
44 d_inode(parent), MAY_EXEC);
45 if (err < 0) {
46 dput(parent);
47 break;
48 }
49 dput(tdentry);
50 tdentry = parent;
51 }
52 if (tdentry != exp->ex_path.dentry)
53 dprintk("nfsd_acceptable failed at %p %pd\n", tdentry, tdentry);
54 rv = (tdentry == exp->ex_path.dentry);
55 dput(tdentry);
56 return rv;
57 }
58
59 /* Type check. The correct error return for type mismatches does not seem to be
60 * generally agreed upon. SunOS seems to use EISDIR if file isn't S_IFREG; a
61 * comment in the NFSv3 spec says this is incorrect (implementation notes for
62 * the write call).
63 */
64 static inline __be32
nfsd_mode_check(struct svc_rqst * rqstp,struct dentry * dentry,umode_t requested)65 nfsd_mode_check(struct svc_rqst *rqstp, struct dentry *dentry,
66 umode_t requested)
67 {
68 umode_t mode = d_inode(dentry)->i_mode & S_IFMT;
69
70 if (requested == 0) /* the caller doesn't care */
71 return nfs_ok;
72 if (mode == requested) {
73 if (mode == S_IFDIR && !d_can_lookup(dentry)) {
74 WARN_ON_ONCE(1);
75 return nfserr_notdir;
76 }
77 return nfs_ok;
78 }
79 /*
80 * v4 has an error more specific than err_notdir which we should
81 * return in preference to err_notdir:
82 */
83 if (rqstp->rq_vers == 4 && mode == S_IFLNK)
84 return nfserr_symlink;
85 if (requested == S_IFDIR)
86 return nfserr_notdir;
87 if (mode == S_IFDIR)
88 return nfserr_isdir;
89 return nfserr_inval;
90 }
91
nfsd_originating_port_ok(struct svc_rqst * rqstp,int flags)92 static bool nfsd_originating_port_ok(struct svc_rqst *rqstp, int flags)
93 {
94 if (flags & NFSEXP_INSECURE_PORT)
95 return true;
96 /* We don't require gss requests to use low ports: */
97 if (rqstp->rq_cred.cr_flavor >= RPC_AUTH_GSS)
98 return true;
99 return test_bit(RQ_SECURE, &rqstp->rq_flags);
100 }
101
nfsd_setuser_and_check_port(struct svc_rqst * rqstp,struct svc_export * exp)102 static __be32 nfsd_setuser_and_check_port(struct svc_rqst *rqstp,
103 struct svc_export *exp)
104 {
105 int flags = nfsexp_flags(rqstp, exp);
106
107 /* Check if the request originated from a secure port. */
108 if (!nfsd_originating_port_ok(rqstp, flags)) {
109 RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
110 dprintk("nfsd: request from insecure port %s!\n",
111 svc_print_addr(rqstp, buf, sizeof(buf)));
112 return nfserr_perm;
113 }
114
115 /* Set user creds for this exportpoint */
116 return nfserrno(nfsd_setuser(rqstp, exp));
117 }
118
check_pseudo_root(struct svc_rqst * rqstp,struct dentry * dentry,struct svc_export * exp)119 static inline __be32 check_pseudo_root(struct svc_rqst *rqstp,
120 struct dentry *dentry, struct svc_export *exp)
121 {
122 if (!(exp->ex_flags & NFSEXP_V4ROOT))
123 return nfs_ok;
124 /*
125 * v2/v3 clients have no need for the V4ROOT export--they use
126 * the mount protocl instead; also, further V4ROOT checks may be
127 * in v4-specific code, in which case v2/v3 clients could bypass
128 * them.
129 */
130 if (!nfsd_v4client(rqstp))
131 return nfserr_stale;
132 /*
133 * We're exposing only the directories and symlinks that have to be
134 * traversed on the way to real exports:
135 */
136 if (unlikely(!d_is_dir(dentry) &&
137 !d_is_symlink(dentry)))
138 return nfserr_stale;
139 /*
140 * A pseudoroot export gives permission to access only one
141 * single directory; the kernel has to make another upcall
142 * before granting access to anything else under it:
143 */
144 if (unlikely(dentry != exp->ex_path.dentry))
145 return nfserr_stale;
146 return nfs_ok;
147 }
148
149 /*
150 * Use the given filehandle to look up the corresponding export and
151 * dentry. On success, the results are used to set fh_export and
152 * fh_dentry.
153 */
nfsd_set_fh_dentry(struct svc_rqst * rqstp,struct svc_fh * fhp)154 static __be32 nfsd_set_fh_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp)
155 {
156 struct knfsd_fh *fh = &fhp->fh_handle;
157 struct fid *fid = NULL;
158 struct svc_export *exp;
159 struct dentry *dentry;
160 int fileid_type;
161 int data_left = fh->fh_size/4;
162 int len;
163 __be32 error;
164
165 error = nfserr_stale;
166 if (rqstp->rq_vers > 2)
167 error = nfserr_badhandle;
168 if (rqstp->rq_vers == 4 && fh->fh_size == 0)
169 return nfserr_nofilehandle;
170
171 if (fh->fh_version != 1)
172 return error;
173
174 if (--data_left < 0)
175 return error;
176 if (fh->fh_auth_type != 0)
177 return error;
178 len = key_len(fh->fh_fsid_type) / 4;
179 if (len == 0)
180 return error;
181 if (fh->fh_fsid_type == FSID_MAJOR_MINOR) {
182 /* deprecated, convert to type 3 */
183 len = key_len(FSID_ENCODE_DEV)/4;
184 fh->fh_fsid_type = FSID_ENCODE_DEV;
185 /*
186 * struct knfsd_fh uses host-endian fields, which are
187 * sometimes used to hold net-endian values. This
188 * confuses sparse, so we must use __force here to
189 * keep it from complaining.
190 */
191 fh->fh_fsid[0] = new_encode_dev(MKDEV(ntohl((__force __be32)fh->fh_fsid[0]),
192 ntohl((__force __be32)fh->fh_fsid[1])));
193 fh->fh_fsid[1] = fh->fh_fsid[2];
194 }
195 data_left -= len;
196 if (data_left < 0)
197 return error;
198 exp = rqst_exp_find(rqstp, fh->fh_fsid_type, fh->fh_fsid);
199 fid = (struct fid *)(fh->fh_fsid + len);
200
201 error = nfserr_stale;
202 if (IS_ERR(exp)) {
203 trace_nfsd_set_fh_dentry_badexport(rqstp, fhp, PTR_ERR(exp));
204
205 if (PTR_ERR(exp) == -ENOENT)
206 return error;
207
208 return nfserrno(PTR_ERR(exp));
209 }
210
211 if (exp->ex_flags & NFSEXP_NOSUBTREECHECK) {
212 /* Elevate privileges so that the lack of 'r' or 'x'
213 * permission on some parent directory will
214 * not stop exportfs_decode_fh from being able
215 * to reconnect a directory into the dentry cache.
216 * The same problem can affect "SUBTREECHECK" exports,
217 * but as nfsd_acceptable depends on correct
218 * access control settings being in effect, we cannot
219 * fix that case easily.
220 */
221 struct cred *new = prepare_creds();
222 if (!new) {
223 error = nfserrno(-ENOMEM);
224 goto out;
225 }
226 new->cap_effective =
227 cap_raise_nfsd_set(new->cap_effective,
228 new->cap_permitted);
229 put_cred(override_creds(new));
230 put_cred(new);
231 } else {
232 error = nfsd_setuser_and_check_port(rqstp, exp);
233 if (error)
234 goto out;
235 }
236
237 /*
238 * Look up the dentry using the NFS file handle.
239 */
240 error = nfserr_stale;
241 if (rqstp->rq_vers > 2)
242 error = nfserr_badhandle;
243
244 fileid_type = fh->fh_fileid_type;
245
246 if (fileid_type == FILEID_ROOT)
247 dentry = dget(exp->ex_path.dentry);
248 else {
249 dentry = exportfs_decode_fh_raw(exp->ex_path.mnt, fid,
250 data_left, fileid_type,
251 nfsd_acceptable, exp);
252 if (IS_ERR_OR_NULL(dentry)) {
253 trace_nfsd_set_fh_dentry_badhandle(rqstp, fhp,
254 dentry ? PTR_ERR(dentry) : -ESTALE);
255 switch (PTR_ERR(dentry)) {
256 case -ENOMEM:
257 case -ETIMEDOUT:
258 break;
259 default:
260 dentry = ERR_PTR(-ESTALE);
261 }
262 }
263 }
264 if (dentry == NULL)
265 goto out;
266 if (IS_ERR(dentry)) {
267 if (PTR_ERR(dentry) != -EINVAL)
268 error = nfserrno(PTR_ERR(dentry));
269 goto out;
270 }
271
272 if (d_is_dir(dentry) &&
273 (dentry->d_flags & DCACHE_DISCONNECTED)) {
274 printk("nfsd: find_fh_dentry returned a DISCONNECTED directory: %pd2\n",
275 dentry);
276 }
277
278 fhp->fh_dentry = dentry;
279 fhp->fh_export = exp;
280
281 switch (rqstp->rq_vers) {
282 case 4:
283 if (dentry->d_sb->s_export_op->flags & EXPORT_OP_NOATOMIC_ATTR)
284 fhp->fh_no_atomic_attr = true;
285 break;
286 case 3:
287 if (dentry->d_sb->s_export_op->flags & EXPORT_OP_NOWCC)
288 fhp->fh_no_wcc = true;
289 break;
290 case 2:
291 fhp->fh_no_wcc = true;
292 }
293
294 return 0;
295 out:
296 exp_put(exp);
297 return error;
298 }
299
300 /**
301 * fh_verify - filehandle lookup and access checking
302 * @rqstp: pointer to current rpc request
303 * @fhp: filehandle to be verified
304 * @type: expected type of object pointed to by filehandle
305 * @access: type of access needed to object
306 *
307 * Look up a dentry from the on-the-wire filehandle, check the client's
308 * access to the export, and set the current task's credentials.
309 *
310 * Regardless of success or failure of fh_verify(), fh_put() should be
311 * called on @fhp when the caller is finished with the filehandle.
312 *
313 * fh_verify() may be called multiple times on a given filehandle, for
314 * example, when processing an NFSv4 compound. The first call will look
315 * up a dentry using the on-the-wire filehandle. Subsequent calls will
316 * skip the lookup and just perform the other checks and possibly change
317 * the current task's credentials.
318 *
319 * @type specifies the type of object expected using one of the S_IF*
320 * constants defined in include/linux/stat.h. The caller may use zero
321 * to indicate that it doesn't care, or a negative integer to indicate
322 * that it expects something not of the given type.
323 *
324 * @access is formed from the NFSD_MAY_* constants defined in
325 * fs/nfsd/vfs.h.
326 */
327 __be32
fh_verify(struct svc_rqst * rqstp,struct svc_fh * fhp,umode_t type,int access)328 fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type, int access)
329 {
330 struct svc_export *exp = NULL;
331 struct dentry *dentry;
332 __be32 error;
333
334 if (!fhp->fh_dentry) {
335 error = nfsd_set_fh_dentry(rqstp, fhp);
336 if (error)
337 goto out;
338 }
339 dentry = fhp->fh_dentry;
340 exp = fhp->fh_export;
341
342 trace_nfsd_fh_verify(rqstp, fhp, type, access);
343
344 /*
345 * We still have to do all these permission checks, even when
346 * fh_dentry is already set:
347 * - fh_verify may be called multiple times with different
348 * "access" arguments (e.g. nfsd_proc_create calls
349 * fh_verify(...,NFSD_MAY_EXEC) first, then later (in
350 * nfsd_create) calls fh_verify(...,NFSD_MAY_CREATE).
351 * - in the NFSv4 case, the filehandle may have been filled
352 * in by fh_compose, and given a dentry, but further
353 * compound operations performed with that filehandle
354 * still need permissions checks. In the worst case, a
355 * mountpoint crossing may have changed the export
356 * options, and we may now need to use a different uid
357 * (for example, if different id-squashing options are in
358 * effect on the new filesystem).
359 */
360 error = check_pseudo_root(rqstp, dentry, exp);
361 if (error)
362 goto out;
363
364 error = nfsd_setuser_and_check_port(rqstp, exp);
365 if (error)
366 goto out;
367
368 error = nfsd_mode_check(rqstp, dentry, type);
369 if (error)
370 goto out;
371
372 /*
373 * pseudoflavor restrictions are not enforced on NLM,
374 * which clients virtually always use auth_sys for,
375 * even while using RPCSEC_GSS for NFS.
376 */
377 if (access & NFSD_MAY_LOCK || access & NFSD_MAY_BYPASS_GSS)
378 goto skip_pseudoflavor_check;
379 /*
380 * Clients may expect to be able to use auth_sys during mount,
381 * even if they use gss for everything else; see section 2.3.2
382 * of rfc 2623.
383 */
384 if (access & NFSD_MAY_BYPASS_GSS_ON_ROOT
385 && exp->ex_path.dentry == dentry)
386 goto skip_pseudoflavor_check;
387
388 error = check_nfsd_access(exp, rqstp);
389 if (error)
390 goto out;
391
392 skip_pseudoflavor_check:
393 /* Finally, check access permissions. */
394 error = nfsd_permission(rqstp, exp, dentry, access);
395 out:
396 trace_nfsd_fh_verify_err(rqstp, fhp, type, access, error);
397 if (error == nfserr_stale)
398 nfsd_stats_fh_stale_inc(exp);
399 return error;
400 }
401
402
403 /*
404 * Compose a file handle for an NFS reply.
405 *
406 * Note that when first composed, the dentry may not yet have
407 * an inode. In this case a call to fh_update should be made
408 * before the fh goes out on the wire ...
409 */
_fh_update(struct svc_fh * fhp,struct svc_export * exp,struct dentry * dentry)410 static void _fh_update(struct svc_fh *fhp, struct svc_export *exp,
411 struct dentry *dentry)
412 {
413 if (dentry != exp->ex_path.dentry) {
414 struct fid *fid = (struct fid *)
415 (fhp->fh_handle.fh_fsid + fhp->fh_handle.fh_size/4 - 1);
416 int maxsize = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4;
417 int fh_flags = (exp->ex_flags & NFSEXP_NOSUBTREECHECK) ? 0 :
418 EXPORT_FH_CONNECTABLE;
419 int fileid_type =
420 exportfs_encode_fh(dentry, fid, &maxsize, fh_flags);
421
422 fhp->fh_handle.fh_fileid_type =
423 fileid_type > 0 ? fileid_type : FILEID_INVALID;
424 fhp->fh_handle.fh_size += maxsize * 4;
425 } else {
426 fhp->fh_handle.fh_fileid_type = FILEID_ROOT;
427 }
428 }
429
is_root_export(struct svc_export * exp)430 static bool is_root_export(struct svc_export *exp)
431 {
432 return exp->ex_path.dentry == exp->ex_path.dentry->d_sb->s_root;
433 }
434
exp_sb(struct svc_export * exp)435 static struct super_block *exp_sb(struct svc_export *exp)
436 {
437 return exp->ex_path.dentry->d_sb;
438 }
439
fsid_type_ok_for_exp(u8 fsid_type,struct svc_export * exp)440 static bool fsid_type_ok_for_exp(u8 fsid_type, struct svc_export *exp)
441 {
442 switch (fsid_type) {
443 case FSID_DEV:
444 if (!old_valid_dev(exp_sb(exp)->s_dev))
445 return false;
446 fallthrough;
447 case FSID_MAJOR_MINOR:
448 case FSID_ENCODE_DEV:
449 return exp_sb(exp)->s_type->fs_flags & FS_REQUIRES_DEV;
450 case FSID_NUM:
451 return exp->ex_flags & NFSEXP_FSID;
452 case FSID_UUID8:
453 case FSID_UUID16:
454 if (!is_root_export(exp))
455 return false;
456 fallthrough;
457 case FSID_UUID4_INUM:
458 case FSID_UUID16_INUM:
459 return exp->ex_uuid != NULL;
460 }
461 return true;
462 }
463
464
set_version_and_fsid_type(struct svc_fh * fhp,struct svc_export * exp,struct svc_fh * ref_fh)465 static void set_version_and_fsid_type(struct svc_fh *fhp, struct svc_export *exp, struct svc_fh *ref_fh)
466 {
467 u8 version;
468 u8 fsid_type;
469 retry:
470 version = 1;
471 if (ref_fh && ref_fh->fh_export == exp) {
472 version = ref_fh->fh_handle.fh_version;
473 fsid_type = ref_fh->fh_handle.fh_fsid_type;
474
475 ref_fh = NULL;
476
477 switch (version) {
478 case 0xca:
479 fsid_type = FSID_DEV;
480 break;
481 case 1:
482 break;
483 default:
484 goto retry;
485 }
486
487 /*
488 * As the fsid -> filesystem mapping was guided by
489 * user-space, there is no guarantee that the filesystem
490 * actually supports that fsid type. If it doesn't we
491 * loop around again without ref_fh set.
492 */
493 if (!fsid_type_ok_for_exp(fsid_type, exp))
494 goto retry;
495 } else if (exp->ex_flags & NFSEXP_FSID) {
496 fsid_type = FSID_NUM;
497 } else if (exp->ex_uuid) {
498 if (fhp->fh_maxsize >= 64) {
499 if (is_root_export(exp))
500 fsid_type = FSID_UUID16;
501 else
502 fsid_type = FSID_UUID16_INUM;
503 } else {
504 if (is_root_export(exp))
505 fsid_type = FSID_UUID8;
506 else
507 fsid_type = FSID_UUID4_INUM;
508 }
509 } else if (!old_valid_dev(exp_sb(exp)->s_dev))
510 /* for newer device numbers, we must use a newer fsid format */
511 fsid_type = FSID_ENCODE_DEV;
512 else
513 fsid_type = FSID_DEV;
514 fhp->fh_handle.fh_version = version;
515 if (version)
516 fhp->fh_handle.fh_fsid_type = fsid_type;
517 }
518
519 __be32
fh_compose(struct svc_fh * fhp,struct svc_export * exp,struct dentry * dentry,struct svc_fh * ref_fh)520 fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry,
521 struct svc_fh *ref_fh)
522 {
523 /* ref_fh is a reference file handle.
524 * if it is non-null and for the same filesystem, then we should compose
525 * a filehandle which is of the same version, where possible.
526 */
527
528 struct inode * inode = d_inode(dentry);
529 dev_t ex_dev = exp_sb(exp)->s_dev;
530
531 dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %pd2, ino=%ld)\n",
532 MAJOR(ex_dev), MINOR(ex_dev),
533 (long) d_inode(exp->ex_path.dentry)->i_ino,
534 dentry,
535 (inode ? inode->i_ino : 0));
536
537 /* Choose filehandle version and fsid type based on
538 * the reference filehandle (if it is in the same export)
539 * or the export options.
540 */
541 set_version_and_fsid_type(fhp, exp, ref_fh);
542
543 /* If we have a ref_fh, then copy the fh_no_wcc setting from it. */
544 fhp->fh_no_wcc = ref_fh ? ref_fh->fh_no_wcc : false;
545
546 if (ref_fh == fhp)
547 fh_put(ref_fh);
548
549 if (fhp->fh_dentry) {
550 printk(KERN_ERR "fh_compose: fh %pd2 not initialized!\n",
551 dentry);
552 }
553 if (fhp->fh_maxsize < NFS_FHSIZE)
554 printk(KERN_ERR "fh_compose: called with maxsize %d! %pd2\n",
555 fhp->fh_maxsize,
556 dentry);
557
558 fhp->fh_dentry = dget(dentry); /* our internal copy */
559 fhp->fh_export = exp_get(exp);
560
561 fhp->fh_handle.fh_size =
562 key_len(fhp->fh_handle.fh_fsid_type) + 4;
563 fhp->fh_handle.fh_auth_type = 0;
564
565 mk_fsid(fhp->fh_handle.fh_fsid_type,
566 fhp->fh_handle.fh_fsid,
567 ex_dev,
568 d_inode(exp->ex_path.dentry)->i_ino,
569 exp->ex_fsid, exp->ex_uuid);
570
571 if (inode)
572 _fh_update(fhp, exp, dentry);
573 if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID) {
574 fh_put(fhp);
575 return nfserr_opnotsupp;
576 }
577
578 return 0;
579 }
580
581 /*
582 * Update file handle information after changing a dentry.
583 * This is only called by nfsd_create, nfsd_create_v3 and nfsd_proc_create
584 */
585 __be32
fh_update(struct svc_fh * fhp)586 fh_update(struct svc_fh *fhp)
587 {
588 struct dentry *dentry;
589
590 if (!fhp->fh_dentry)
591 goto out_bad;
592
593 dentry = fhp->fh_dentry;
594 if (d_really_is_negative(dentry))
595 goto out_negative;
596 if (fhp->fh_handle.fh_fileid_type != FILEID_ROOT)
597 return 0;
598
599 _fh_update(fhp, fhp->fh_export, dentry);
600 if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID)
601 return nfserr_opnotsupp;
602 return 0;
603 out_bad:
604 printk(KERN_ERR "fh_update: fh not verified!\n");
605 return nfserr_serverfault;
606 out_negative:
607 printk(KERN_ERR "fh_update: %pd2 still negative!\n",
608 dentry);
609 return nfserr_serverfault;
610 }
611
612 /**
613 * fh_fill_pre_attrs - Fill in pre-op attributes
614 * @fhp: file handle to be updated
615 *
616 */
fh_fill_pre_attrs(struct svc_fh * fhp)617 __be32 __must_check fh_fill_pre_attrs(struct svc_fh *fhp)
618 {
619 bool v4 = (fhp->fh_maxsize == NFS4_FHSIZE);
620 struct inode *inode;
621 struct kstat stat;
622 __be32 err;
623
624 if (fhp->fh_no_wcc || fhp->fh_pre_saved)
625 return nfs_ok;
626
627 inode = d_inode(fhp->fh_dentry);
628 err = fh_getattr(fhp, &stat);
629 if (err)
630 return err;
631
632 if (v4)
633 fhp->fh_pre_change = nfsd4_change_attribute(&stat, inode);
634
635 fhp->fh_pre_mtime = stat.mtime;
636 fhp->fh_pre_ctime = stat.ctime;
637 fhp->fh_pre_size = stat.size;
638 fhp->fh_pre_saved = true;
639 return nfs_ok;
640 }
641
642 /**
643 * fh_fill_post_attrs - Fill in post-op attributes
644 * @fhp: file handle to be updated
645 *
646 */
fh_fill_post_attrs(struct svc_fh * fhp)647 __be32 fh_fill_post_attrs(struct svc_fh *fhp)
648 {
649 bool v4 = (fhp->fh_maxsize == NFS4_FHSIZE);
650 struct inode *inode = d_inode(fhp->fh_dentry);
651 __be32 err;
652
653 if (fhp->fh_no_wcc)
654 return nfs_ok;
655
656 if (fhp->fh_post_saved)
657 printk("nfsd: inode locked twice during operation.\n");
658
659 err = fh_getattr(fhp, &fhp->fh_post_attr);
660 if (err)
661 return err;
662
663 fhp->fh_post_saved = true;
664 if (v4)
665 fhp->fh_post_change =
666 nfsd4_change_attribute(&fhp->fh_post_attr, inode);
667 return nfs_ok;
668 }
669
670 /**
671 * fh_fill_both_attrs - Fill pre-op and post-op attributes
672 * @fhp: file handle to be updated
673 *
674 * This is used when the directory wasn't changed, but wcc attributes
675 * are needed anyway.
676 */
fh_fill_both_attrs(struct svc_fh * fhp)677 __be32 __must_check fh_fill_both_attrs(struct svc_fh *fhp)
678 {
679 __be32 err;
680
681 err = fh_fill_post_attrs(fhp);
682 if (err)
683 return err;
684
685 fhp->fh_pre_change = fhp->fh_post_change;
686 fhp->fh_pre_mtime = fhp->fh_post_attr.mtime;
687 fhp->fh_pre_ctime = fhp->fh_post_attr.ctime;
688 fhp->fh_pre_size = fhp->fh_post_attr.size;
689 fhp->fh_pre_saved = true;
690 return nfs_ok;
691 }
692
693 /*
694 * Release a file handle.
695 */
696 void
fh_put(struct svc_fh * fhp)697 fh_put(struct svc_fh *fhp)
698 {
699 struct dentry * dentry = fhp->fh_dentry;
700 struct svc_export * exp = fhp->fh_export;
701 if (dentry) {
702 fhp->fh_dentry = NULL;
703 dput(dentry);
704 fh_clear_pre_post_attrs(fhp);
705 }
706 fh_drop_write(fhp);
707 if (exp) {
708 exp_put(exp);
709 fhp->fh_export = NULL;
710 }
711 fhp->fh_no_wcc = false;
712 return;
713 }
714
715 /*
716 * Shorthand for dprintk()'s
717 */
SVCFH_fmt(struct svc_fh * fhp)718 char * SVCFH_fmt(struct svc_fh *fhp)
719 {
720 struct knfsd_fh *fh = &fhp->fh_handle;
721 static char buf[2+1+1+64*3+1];
722
723 if (fh->fh_size < 0 || fh->fh_size> 64)
724 return "bad-fh";
725 sprintf(buf, "%d: %*ph", fh->fh_size, fh->fh_size, fh->fh_raw);
726 return buf;
727 }
728
fsid_source(const struct svc_fh * fhp)729 enum fsid_source fsid_source(const struct svc_fh *fhp)
730 {
731 if (fhp->fh_handle.fh_version != 1)
732 return FSIDSOURCE_DEV;
733 switch(fhp->fh_handle.fh_fsid_type) {
734 case FSID_DEV:
735 case FSID_ENCODE_DEV:
736 case FSID_MAJOR_MINOR:
737 if (exp_sb(fhp->fh_export)->s_type->fs_flags & FS_REQUIRES_DEV)
738 return FSIDSOURCE_DEV;
739 break;
740 case FSID_NUM:
741 if (fhp->fh_export->ex_flags & NFSEXP_FSID)
742 return FSIDSOURCE_FSID;
743 break;
744 default:
745 break;
746 }
747 /* either a UUID type filehandle, or the filehandle doesn't
748 * match the export.
749 */
750 if (fhp->fh_export->ex_flags & NFSEXP_FSID)
751 return FSIDSOURCE_FSID;
752 if (fhp->fh_export->ex_uuid)
753 return FSIDSOURCE_UUID;
754 return FSIDSOURCE_DEV;
755 }
756
757 /*
758 * We could use i_version alone as the change attribute. However, i_version
759 * can go backwards on a regular file after an unclean shutdown. On its own
760 * that doesn't necessarily cause a problem, but if i_version goes backwards
761 * and then is incremented again it could reuse a value that was previously
762 * used before boot, and a client who queried the two values might incorrectly
763 * assume nothing changed.
764 *
765 * By using both ctime and the i_version counter we guarantee that as long as
766 * time doesn't go backwards we never reuse an old value. If the filesystem
767 * advertises STATX_ATTR_CHANGE_MONOTONIC, then this mitigation is not
768 * needed.
769 *
770 * We only need to do this for regular files as well. For directories, we
771 * assume that the new change attr is always logged to stable storage in some
772 * fashion before the results can be seen.
773 */
nfsd4_change_attribute(struct kstat * stat,struct inode * inode)774 u64 nfsd4_change_attribute(struct kstat *stat, struct inode *inode)
775 {
776 u64 chattr;
777
778 if (stat->result_mask & STATX_CHANGE_COOKIE) {
779 chattr = stat->change_cookie;
780 if (S_ISREG(inode->i_mode) &&
781 !(stat->attributes & STATX_ATTR_CHANGE_MONOTONIC)) {
782 chattr += (u64)stat->ctime.tv_sec << 30;
783 chattr += stat->ctime.tv_nsec;
784 }
785 } else {
786 chattr = time_to_chattr(&stat->ctime);
787 }
788 return chattr;
789 }
790