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 dentry * dentry,umode_t requested)65 nfsd_mode_check(struct dentry *dentry, umode_t requested)
66 {
67 umode_t mode = d_inode(dentry)->i_mode & S_IFMT;
68
69 if (requested == 0) /* the caller doesn't care */
70 return nfs_ok;
71 if (mode == requested) {
72 if (mode == S_IFDIR && !d_can_lookup(dentry)) {
73 WARN_ON_ONCE(1);
74 return nfserr_notdir;
75 }
76 return nfs_ok;
77 }
78 if (mode == S_IFLNK) {
79 if (requested == S_IFDIR)
80 return nfserr_symlink_not_dir;
81 return nfserr_symlink;
82 }
83 if (requested == S_IFDIR)
84 return nfserr_notdir;
85 if (mode == S_IFDIR)
86 return nfserr_isdir;
87 return nfserr_wrong_type;
88 }
89
nfsd_originating_port_ok(struct svc_rqst * rqstp,struct svc_cred * cred,struct svc_export * exp)90 static bool nfsd_originating_port_ok(struct svc_rqst *rqstp,
91 struct svc_cred *cred,
92 struct svc_export *exp)
93 {
94 if (nfsexp_flags(cred, exp) & NFSEXP_INSECURE_PORT)
95 return true;
96 /* We don't require gss requests to use low ports: */
97 if (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_cred * cred,struct svc_export * exp)102 static __be32 nfsd_setuser_and_check_port(struct svc_rqst *rqstp,
103 struct svc_cred *cred,
104 struct svc_export *exp)
105 {
106 /* Check if the request originated from a secure port. */
107 if (rqstp && !nfsd_originating_port_ok(rqstp, cred, exp)) {
108 RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
109 dprintk("nfsd: request from insecure port %s!\n",
110 svc_print_addr(rqstp, buf, sizeof(buf)));
111 return nfserr_perm;
112 }
113
114 /* Set user creds for this exportpoint */
115 return nfserrno(nfsd_setuser(cred, exp));
116 }
117
check_pseudo_root(struct dentry * dentry,struct svc_export * exp)118 static inline __be32 check_pseudo_root(struct dentry *dentry,
119 struct svc_export *exp)
120 {
121 if (!(exp->ex_flags & NFSEXP_V4ROOT))
122 return nfs_ok;
123 /*
124 * We're exposing only the directories and symlinks that have to be
125 * traversed on the way to real exports:
126 */
127 if (unlikely(!d_is_dir(dentry) &&
128 !d_is_symlink(dentry)))
129 return nfserr_stale;
130 /*
131 * A pseudoroot export gives permission to access only one
132 * single directory; the kernel has to make another upcall
133 * before granting access to anything else under it:
134 */
135 if (unlikely(dentry != exp->ex_path.dentry))
136 return nfserr_stale;
137 return nfs_ok;
138 }
139
140 /*
141 * Use the given filehandle to look up the corresponding export and
142 * dentry. On success, the results are used to set fh_export and
143 * fh_dentry.
144 */
nfsd_set_fh_dentry(struct svc_rqst * rqstp,struct net * net,struct svc_cred * cred,struct auth_domain * client,struct auth_domain * gssclient,struct svc_fh * fhp)145 static __be32 nfsd_set_fh_dentry(struct svc_rqst *rqstp, struct net *net,
146 struct svc_cred *cred,
147 struct auth_domain *client,
148 struct auth_domain *gssclient,
149 struct svc_fh *fhp)
150 {
151 struct knfsd_fh *fh = &fhp->fh_handle;
152 struct fid *fid = NULL;
153 struct svc_export *exp;
154 struct dentry *dentry;
155 int fileid_type;
156 int data_left = fh->fh_size/4;
157 int len;
158 __be32 error;
159
160 error = nfserr_badhandle;
161 if (fh->fh_size == 0)
162 return nfserr_nofilehandle;
163
164 if (fh->fh_version != 1)
165 return error;
166
167 if (--data_left < 0)
168 return error;
169 if (fh->fh_auth_type != 0)
170 return error;
171 len = key_len(fh->fh_fsid_type) / 4;
172 if (len == 0)
173 return error;
174 if (fh->fh_fsid_type == FSID_MAJOR_MINOR) {
175 u32 *fsid = fh_fsid(fh);
176
177 /* deprecated, convert to type 3 */
178 len = key_len(FSID_ENCODE_DEV)/4;
179 fh->fh_fsid_type = FSID_ENCODE_DEV;
180 /*
181 * struct knfsd_fh uses host-endian fields, which are
182 * sometimes used to hold net-endian values. This
183 * confuses sparse, so we must use __force here to
184 * keep it from complaining.
185 */
186 fsid[0] = new_encode_dev(MKDEV(ntohl((__force __be32)fsid[0]),
187 ntohl((__force __be32)fsid[1])));
188 fsid[1] = fsid[2];
189 }
190 data_left -= len;
191 if (data_left < 0)
192 return error;
193 exp = rqst_exp_find(rqstp ? &rqstp->rq_chandle : NULL,
194 net, client, gssclient,
195 fh->fh_fsid_type, fh_fsid(fh));
196 fid = (struct fid *)(fh_fsid(fh) + len);
197
198 error = nfserr_stale;
199 if (IS_ERR(exp)) {
200 trace_nfsd_set_fh_dentry_badexport(rqstp, fhp, PTR_ERR(exp));
201
202 if (PTR_ERR(exp) == -ENOENT)
203 return error;
204
205 return nfserrno(PTR_ERR(exp));
206 }
207
208 if (exp->ex_flags & NFSEXP_NOSUBTREECHECK) {
209 /* Elevate privileges so that the lack of 'r' or 'x'
210 * permission on some parent directory will
211 * not stop exportfs_decode_fh from being able
212 * to reconnect a directory into the dentry cache.
213 * The same problem can affect "SUBTREECHECK" exports,
214 * but as nfsd_acceptable depends on correct
215 * access control settings being in effect, we cannot
216 * fix that case easily.
217 */
218 struct cred *new = prepare_creds();
219 if (!new) {
220 error = nfserrno(-ENOMEM);
221 goto out;
222 }
223 new->cap_effective =
224 cap_raise_nfsd_set(new->cap_effective,
225 new->cap_permitted);
226 put_cred(override_creds(new));
227 } else {
228 error = nfsd_setuser_and_check_port(rqstp, cred, exp);
229 if (error)
230 goto out;
231 }
232
233 /*
234 * Look up the dentry using the NFS file handle.
235 */
236 error = nfserr_badhandle;
237
238 fileid_type = fh->fh_fileid_type;
239
240 if (fileid_type == FILEID_ROOT)
241 dentry = dget(exp->ex_path.dentry);
242 else {
243 dentry = exportfs_decode_fh_raw(exp->ex_path.mnt, fid,
244 data_left, fileid_type, 0,
245 nfsd_acceptable, exp);
246 if (IS_ERR_OR_NULL(dentry)) {
247 trace_nfsd_set_fh_dentry_badhandle(rqstp, fhp,
248 dentry ? PTR_ERR(dentry) : -ESTALE);
249 switch (PTR_ERR(dentry)) {
250 case -ENOMEM:
251 case -ETIMEDOUT:
252 break;
253 default:
254 dentry = ERR_PTR(-ESTALE);
255 }
256 }
257 }
258 if (dentry == NULL)
259 goto out;
260 if (IS_ERR(dentry)) {
261 if (PTR_ERR(dentry) != -EINVAL)
262 error = nfserrno(PTR_ERR(dentry));
263 goto out;
264 }
265
266 if (d_is_dir(dentry) &&
267 (dentry->d_flags & DCACHE_DISCONNECTED)) {
268 printk("nfsd: find_fh_dentry returned a DISCONNECTED directory: %pd2\n",
269 dentry);
270 }
271
272 fhp->fh_dentry = dentry;
273 fhp->fh_export = exp;
274
275 switch (fhp->fh_maxsize) {
276 case NFS4_FHSIZE:
277 if (dentry->d_sb->s_export_op->flags & EXPORT_OP_NOATOMIC_ATTR)
278 fhp->fh_no_atomic_attr = true;
279 fhp->fh_64bit_cookies = true;
280 break;
281 case NFS3_FHSIZE:
282 if (dentry->d_sb->s_export_op->flags & EXPORT_OP_NOWCC)
283 fhp->fh_no_wcc = true;
284 fhp->fh_64bit_cookies = true;
285 if (exp->ex_flags & NFSEXP_V4ROOT)
286 goto out;
287 break;
288 case NFS_FHSIZE:
289 fhp->fh_no_wcc = true;
290 if (EX_WGATHER(exp))
291 fhp->fh_use_wgather = true;
292 if (exp->ex_flags & NFSEXP_V4ROOT)
293 goto out;
294 }
295
296 return 0;
297 out:
298 exp_put(exp);
299 return error;
300 }
301
302 /**
303 * __fh_verify - filehandle lookup and access checking
304 * @rqstp: RPC transaction context, or NULL
305 * @net: net namespace in which to perform the export lookup
306 * @cred: RPC user credential
307 * @client: RPC auth domain
308 * @gssclient: RPC GSS auth domain, or NULL
309 * @fhp: filehandle to be verified
310 * @type: expected type of object pointed to by filehandle
311 * @access: type of access needed to object
312 *
313 * See fh_verify() for further descriptions of @fhp, @type, and @access.
314 */
315 static __be32
__fh_verify(struct svc_rqst * rqstp,struct net * net,struct svc_cred * cred,struct auth_domain * client,struct auth_domain * gssclient,struct svc_fh * fhp,umode_t type,int access)316 __fh_verify(struct svc_rqst *rqstp,
317 struct net *net, struct svc_cred *cred,
318 struct auth_domain *client,
319 struct auth_domain *gssclient,
320 struct svc_fh *fhp, umode_t type, int access)
321 {
322 struct nfsd_net *nn = net_generic(net, nfsd_net_id);
323 struct svc_export *exp = NULL;
324 bool may_bypass_gss = false;
325 struct dentry *dentry;
326 __be32 error;
327
328 if (!fhp->fh_dentry) {
329 error = nfsd_set_fh_dentry(rqstp, net, cred, client,
330 gssclient, fhp);
331 if (error)
332 goto out;
333 }
334 dentry = fhp->fh_dentry;
335 exp = fhp->fh_export;
336
337 trace_nfsd_fh_verify(rqstp, fhp, type, access);
338
339 /*
340 * We still have to do all these permission checks, even when
341 * fh_dentry is already set:
342 * - fh_verify may be called multiple times with different
343 * "access" arguments (e.g. nfsd_proc_create calls
344 * fh_verify(...,NFSD_MAY_EXEC) first, then later (in
345 * nfsd_create) calls fh_verify(...,NFSD_MAY_CREATE).
346 * - in the NFSv4 case, the filehandle may have been filled
347 * in by fh_compose, and given a dentry, but further
348 * compound operations performed with that filehandle
349 * still need permissions checks. In the worst case, a
350 * mountpoint crossing may have changed the export
351 * options, and we may now need to use a different uid
352 * (for example, if different id-squashing options are in
353 * effect on the new filesystem).
354 */
355 error = check_pseudo_root(dentry, exp);
356 if (error)
357 goto out;
358
359 error = nfsd_setuser_and_check_port(rqstp, cred, exp);
360 if (error)
361 goto out;
362
363 error = nfsd_mode_check(dentry, type);
364 if (error)
365 goto out;
366
367 if ((access & NFSD_MAY_NLM) && (exp->ex_flags & NFSEXP_NOAUTHNLM))
368 /* NLM is allowed to fully bypass authentication */
369 goto out;
370
371 if (access & NFSD_MAY_BYPASS_GSS)
372 may_bypass_gss = true;
373 /*
374 * Clients may expect to be able to use auth_sys during mount,
375 * even if they use gss for everything else; see section 2.3.2
376 * of rfc 2623.
377 */
378 if (access & NFSD_MAY_BYPASS_GSS_ON_ROOT
379 && exp->ex_path.dentry == dentry)
380 may_bypass_gss = true;
381
382 error = check_nfsd_access(exp, rqstp, may_bypass_gss);
383 if (error)
384 goto out;
385 /* During LOCALIO call to fh_verify will be called with a NULL rqstp */
386 if (rqstp)
387 svc_xprt_set_valid(rqstp->rq_xprt);
388
389 /* Finally, check access permissions. */
390 error = nfsd_permission(cred, exp, dentry, access);
391 out:
392 trace_nfsd_fh_verify_err(rqstp, fhp, type, access, error);
393 if (error == nfserr_stale)
394 nfsd_stats_fh_stale_inc(nn, exp);
395 return error;
396 }
397
398 /**
399 * fh_verify_local - filehandle lookup and access checking
400 * @net: net namespace in which to perform the export lookup
401 * @cred: RPC user credential
402 * @client: RPC auth domain
403 * @fhp: filehandle to be verified
404 * @type: expected type of object pointed to by filehandle
405 * @access: type of access needed to object
406 *
407 * This API can be used by callers who do not have an RPC
408 * transaction context (ie are not running in an nfsd thread).
409 *
410 * See fh_verify() for further descriptions of @fhp, @type, and @access.
411 */
412 __be32
fh_verify_local(struct net * net,struct svc_cred * cred,struct auth_domain * client,struct svc_fh * fhp,umode_t type,int access)413 fh_verify_local(struct net *net, struct svc_cred *cred,
414 struct auth_domain *client, struct svc_fh *fhp,
415 umode_t type, int access)
416 {
417 return __fh_verify(NULL, net, cred, client, NULL,
418 fhp, type, access);
419 }
420
421 /**
422 * fh_verify - filehandle lookup and access checking
423 * @rqstp: pointer to current rpc request
424 * @fhp: filehandle to be verified
425 * @type: expected type of object pointed to by filehandle
426 * @access: type of access needed to object
427 *
428 * Look up a dentry from the on-the-wire filehandle, check the client's
429 * access to the export, and set the current task's credentials.
430 *
431 * Regardless of success or failure of fh_verify(), fh_put() should be
432 * called on @fhp when the caller is finished with the filehandle.
433 *
434 * fh_verify() may be called multiple times on a given filehandle, for
435 * example, when processing an NFSv4 compound. The first call will look
436 * up a dentry using the on-the-wire filehandle. Subsequent calls will
437 * skip the lookup and just perform the other checks and possibly change
438 * the current task's credentials.
439 *
440 * @type specifies the type of object expected using one of the S_IF*
441 * constants defined in include/linux/stat.h. The caller may use zero
442 * to indicate that it doesn't care, or a negative integer to indicate
443 * that it expects something not of the given type.
444 *
445 * @access is formed from the NFSD_MAY_* constants defined in
446 * fs/nfsd/vfs.h.
447 */
448 __be32
fh_verify(struct svc_rqst * rqstp,struct svc_fh * fhp,umode_t type,int access)449 fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type, int access)
450 {
451 return __fh_verify(rqstp, SVC_NET(rqstp), &rqstp->rq_cred,
452 rqstp->rq_client, rqstp->rq_gssclient,
453 fhp, type, access);
454 }
455
456 /*
457 * Compose a file handle for an NFS reply.
458 *
459 * Note that when first composed, the dentry may not yet have
460 * an inode. In this case a call to fh_update should be made
461 * before the fh goes out on the wire ...
462 */
_fh_update(struct svc_fh * fhp,struct svc_export * exp,struct dentry * dentry)463 static void _fh_update(struct svc_fh *fhp, struct svc_export *exp,
464 struct dentry *dentry)
465 {
466 if (dentry != exp->ex_path.dentry) {
467 struct fid *fid = (struct fid *)
468 (fh_fsid(&fhp->fh_handle) + fhp->fh_handle.fh_size/4 - 1);
469 int maxsize = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4;
470 int fh_flags = (exp->ex_flags & NFSEXP_NOSUBTREECHECK) ? 0 :
471 EXPORT_FH_CONNECTABLE;
472 int fileid_type =
473 exportfs_encode_fh(dentry, fid, &maxsize, fh_flags);
474
475 fhp->fh_handle.fh_fileid_type =
476 fileid_type > 0 ? fileid_type : FILEID_INVALID;
477 fhp->fh_handle.fh_size += maxsize * 4;
478 } else {
479 fhp->fh_handle.fh_fileid_type = FILEID_ROOT;
480 }
481 }
482
is_root_export(struct svc_export * exp)483 static bool is_root_export(struct svc_export *exp)
484 {
485 return exp->ex_path.dentry == exp->ex_path.dentry->d_sb->s_root;
486 }
487
exp_sb(struct svc_export * exp)488 static struct super_block *exp_sb(struct svc_export *exp)
489 {
490 return exp->ex_path.dentry->d_sb;
491 }
492
fsid_type_ok_for_exp(u8 fsid_type,struct svc_export * exp)493 static bool fsid_type_ok_for_exp(u8 fsid_type, struct svc_export *exp)
494 {
495 switch (fsid_type) {
496 case FSID_DEV:
497 if (!old_valid_dev(exp_sb(exp)->s_dev))
498 return false;
499 fallthrough;
500 case FSID_MAJOR_MINOR:
501 case FSID_ENCODE_DEV:
502 return exp_sb(exp)->s_type->fs_flags & FS_REQUIRES_DEV;
503 case FSID_NUM:
504 return exp->ex_flags & NFSEXP_FSID;
505 case FSID_UUID8:
506 case FSID_UUID16:
507 if (!is_root_export(exp))
508 return false;
509 fallthrough;
510 case FSID_UUID4_INUM:
511 case FSID_UUID16_INUM:
512 return exp->ex_uuid != NULL;
513 }
514 return true;
515 }
516
517
set_version_and_fsid_type(struct svc_fh * fhp,struct svc_export * exp,struct svc_fh * ref_fh)518 static void set_version_and_fsid_type(struct svc_fh *fhp, struct svc_export *exp, struct svc_fh *ref_fh)
519 {
520 u8 version;
521 u8 fsid_type;
522 retry:
523 version = 1;
524 if (ref_fh && ref_fh->fh_export == exp) {
525 version = ref_fh->fh_handle.fh_version;
526 fsid_type = ref_fh->fh_handle.fh_fsid_type;
527
528 ref_fh = NULL;
529
530 switch (version) {
531 case 0xca:
532 fsid_type = FSID_DEV;
533 break;
534 case 1:
535 break;
536 default:
537 goto retry;
538 }
539
540 /*
541 * As the fsid -> filesystem mapping was guided by
542 * user-space, there is no guarantee that the filesystem
543 * actually supports that fsid type. If it doesn't we
544 * loop around again without ref_fh set.
545 */
546 if (!fsid_type_ok_for_exp(fsid_type, exp))
547 goto retry;
548 } else if (exp->ex_flags & NFSEXP_FSID) {
549 fsid_type = FSID_NUM;
550 } else if (exp->ex_uuid) {
551 if (fhp->fh_maxsize >= 64) {
552 if (is_root_export(exp))
553 fsid_type = FSID_UUID16;
554 else
555 fsid_type = FSID_UUID16_INUM;
556 } else {
557 if (is_root_export(exp))
558 fsid_type = FSID_UUID8;
559 else
560 fsid_type = FSID_UUID4_INUM;
561 }
562 } else if (!old_valid_dev(exp_sb(exp)->s_dev))
563 /* for newer device numbers, we must use a newer fsid format */
564 fsid_type = FSID_ENCODE_DEV;
565 else
566 fsid_type = FSID_DEV;
567 fhp->fh_handle.fh_version = version;
568 if (version)
569 fhp->fh_handle.fh_fsid_type = fsid_type;
570 }
571
572 __be32
fh_compose(struct svc_fh * fhp,struct svc_export * exp,struct dentry * dentry,struct svc_fh * ref_fh)573 fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry,
574 struct svc_fh *ref_fh)
575 {
576 /* ref_fh is a reference file handle.
577 * if it is non-null and for the same filesystem, then we should compose
578 * a filehandle which is of the same version, where possible.
579 */
580
581 struct inode * inode = d_inode(dentry);
582 dev_t ex_dev = exp_sb(exp)->s_dev;
583
584 dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %pd2, ino=%ld)\n",
585 MAJOR(ex_dev), MINOR(ex_dev),
586 (long) d_inode(exp->ex_path.dentry)->i_ino,
587 dentry,
588 (inode ? inode->i_ino : 0));
589
590 /* Choose filehandle version and fsid type based on
591 * the reference filehandle (if it is in the same export)
592 * or the export options.
593 */
594 set_version_and_fsid_type(fhp, exp, ref_fh);
595
596 /* If we have a ref_fh, then copy the fh_no_wcc setting from it. */
597 fhp->fh_no_wcc = ref_fh ? ref_fh->fh_no_wcc : false;
598
599 if (ref_fh == fhp)
600 fh_put(ref_fh);
601
602 if (fhp->fh_dentry) {
603 printk(KERN_ERR "fh_compose: fh %pd2 not initialized!\n",
604 dentry);
605 }
606 if (fhp->fh_maxsize < NFS_FHSIZE)
607 printk(KERN_ERR "fh_compose: called with maxsize %d! %pd2\n",
608 fhp->fh_maxsize,
609 dentry);
610
611 fhp->fh_dentry = dget(dentry); /* our internal copy */
612 fhp->fh_export = exp_get(exp);
613
614 fhp->fh_handle.fh_size =
615 key_len(fhp->fh_handle.fh_fsid_type) + 4;
616 fhp->fh_handle.fh_auth_type = 0;
617
618 mk_fsid(fhp->fh_handle.fh_fsid_type,
619 fh_fsid(&fhp->fh_handle),
620 ex_dev,
621 d_inode(exp->ex_path.dentry)->i_ino,
622 exp->ex_fsid, exp->ex_uuid);
623
624 if (inode)
625 _fh_update(fhp, exp, dentry);
626 if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID) {
627 fh_put(fhp);
628 return nfserr_stale;
629 }
630
631 return 0;
632 }
633
634 /*
635 * Update file handle information after changing a dentry.
636 * This is only called by nfsd_create, nfsd_create_v3 and nfsd_proc_create
637 */
638 __be32
fh_update(struct svc_fh * fhp)639 fh_update(struct svc_fh *fhp)
640 {
641 struct dentry *dentry;
642
643 if (!fhp->fh_dentry)
644 goto out_bad;
645
646 dentry = fhp->fh_dentry;
647 if (d_really_is_negative(dentry))
648 goto out_negative;
649 if (fhp->fh_handle.fh_fileid_type != FILEID_ROOT)
650 return 0;
651
652 _fh_update(fhp, fhp->fh_export, dentry);
653 if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID)
654 return nfserr_stale;
655 return 0;
656 out_bad:
657 printk(KERN_ERR "fh_update: fh not verified!\n");
658 return nfserr_serverfault;
659 out_negative:
660 printk(KERN_ERR "fh_update: %pd2 still negative!\n",
661 dentry);
662 return nfserr_serverfault;
663 }
664
665 /**
666 * fh_fill_pre_attrs - Fill in pre-op attributes
667 * @fhp: file handle to be updated
668 *
669 */
fh_fill_pre_attrs(struct svc_fh * fhp)670 __be32 __must_check fh_fill_pre_attrs(struct svc_fh *fhp)
671 {
672 bool v4 = (fhp->fh_maxsize == NFS4_FHSIZE);
673 struct kstat stat;
674 __be32 err;
675
676 if (fhp->fh_no_wcc || fhp->fh_pre_saved)
677 return nfs_ok;
678
679 err = fh_getattr(fhp, &stat);
680 if (err)
681 return err;
682
683 if (v4)
684 fhp->fh_pre_change = nfsd4_change_attribute(&stat);
685
686 fhp->fh_pre_mtime = stat.mtime;
687 fhp->fh_pre_ctime = stat.ctime;
688 fhp->fh_pre_size = stat.size;
689 fhp->fh_pre_saved = true;
690 return nfs_ok;
691 }
692
693 /**
694 * fh_fill_post_attrs - Fill in post-op attributes
695 * @fhp: file handle to be updated
696 *
697 */
fh_fill_post_attrs(struct svc_fh * fhp)698 __be32 fh_fill_post_attrs(struct svc_fh *fhp)
699 {
700 bool v4 = (fhp->fh_maxsize == NFS4_FHSIZE);
701 __be32 err;
702
703 if (fhp->fh_no_wcc)
704 return nfs_ok;
705
706 if (fhp->fh_post_saved)
707 printk("nfsd: inode locked twice during operation.\n");
708
709 err = fh_getattr(fhp, &fhp->fh_post_attr);
710 if (err)
711 return err;
712
713 fhp->fh_post_saved = true;
714 if (v4)
715 fhp->fh_post_change =
716 nfsd4_change_attribute(&fhp->fh_post_attr);
717 return nfs_ok;
718 }
719
720 /**
721 * fh_fill_both_attrs - Fill pre-op and post-op attributes
722 * @fhp: file handle to be updated
723 *
724 * This is used when the directory wasn't changed, but wcc attributes
725 * are needed anyway.
726 */
fh_fill_both_attrs(struct svc_fh * fhp)727 __be32 __must_check fh_fill_both_attrs(struct svc_fh *fhp)
728 {
729 __be32 err;
730
731 err = fh_fill_post_attrs(fhp);
732 if (err)
733 return err;
734
735 fhp->fh_pre_change = fhp->fh_post_change;
736 fhp->fh_pre_mtime = fhp->fh_post_attr.mtime;
737 fhp->fh_pre_ctime = fhp->fh_post_attr.ctime;
738 fhp->fh_pre_size = fhp->fh_post_attr.size;
739 fhp->fh_pre_saved = true;
740 return nfs_ok;
741 }
742
743 /*
744 * Release a file handle.
745 */
746 void
fh_put(struct svc_fh * fhp)747 fh_put(struct svc_fh *fhp)
748 {
749 struct dentry * dentry = fhp->fh_dentry;
750 struct svc_export * exp = fhp->fh_export;
751 if (dentry) {
752 fhp->fh_dentry = NULL;
753 dput(dentry);
754 fh_clear_pre_post_attrs(fhp);
755 }
756 fh_drop_write(fhp);
757 if (exp) {
758 exp_put(exp);
759 fhp->fh_export = NULL;
760 }
761 fhp->fh_no_wcc = false;
762 return;
763 }
764
765 /*
766 * Shorthand for dprintk()'s
767 */
SVCFH_fmt(struct svc_fh * fhp)768 char * SVCFH_fmt(struct svc_fh *fhp)
769 {
770 struct knfsd_fh *fh = &fhp->fh_handle;
771 static char buf[2+1+1+64*3+1];
772
773 if (fh->fh_size > 64)
774 return "bad-fh";
775 sprintf(buf, "%d: %*ph", fh->fh_size, fh->fh_size, fh->fh_raw);
776 return buf;
777 }
778
fsid_source(const struct svc_fh * fhp)779 enum fsid_source fsid_source(const struct svc_fh *fhp)
780 {
781 if (fhp->fh_handle.fh_version != 1)
782 return FSIDSOURCE_DEV;
783 switch(fhp->fh_handle.fh_fsid_type) {
784 case FSID_DEV:
785 case FSID_ENCODE_DEV:
786 case FSID_MAJOR_MINOR:
787 if (exp_sb(fhp->fh_export)->s_type->fs_flags & FS_REQUIRES_DEV)
788 return FSIDSOURCE_DEV;
789 break;
790 case FSID_NUM:
791 if (fhp->fh_export->ex_flags & NFSEXP_FSID)
792 return FSIDSOURCE_FSID;
793 break;
794 default:
795 break;
796 }
797 /* either a UUID type filehandle, or the filehandle doesn't
798 * match the export.
799 */
800 if (fhp->fh_export->ex_flags & NFSEXP_FSID)
801 return FSIDSOURCE_FSID;
802 if (fhp->fh_export->ex_uuid)
803 return FSIDSOURCE_UUID;
804 return FSIDSOURCE_DEV;
805 }
806
807 /**
808 * nfsd4_change_attribute - Generate an NFSv4 change_attribute value
809 * @stat: inode attributes
810 *
811 * Caller must fill in @stat before calling, typically by invoking
812 * vfs_getattr() with STATX_MODE, STATX_CTIME, and STATX_CHANGE_COOKIE.
813 * Returns an unsigned 64-bit changeid4 value (RFC 8881 Section 3.2).
814 *
815 * We could use i_version alone as the change attribute. However, i_version
816 * can go backwards on a regular file after an unclean shutdown. On its own
817 * that doesn't necessarily cause a problem, but if i_version goes backwards
818 * and then is incremented again it could reuse a value that was previously
819 * used before boot, and a client who queried the two values might incorrectly
820 * assume nothing changed.
821 *
822 * By using both ctime and the i_version counter we guarantee that as long as
823 * time doesn't go backwards we never reuse an old value. If the filesystem
824 * advertises STATX_ATTR_CHANGE_MONOTONIC, then this mitigation is not
825 * needed.
826 *
827 * We only need to do this for regular files as well. For directories, we
828 * assume that the new change attr is always logged to stable storage in some
829 * fashion before the results can be seen.
830 */
nfsd4_change_attribute(const struct kstat * stat)831 u64 nfsd4_change_attribute(const struct kstat *stat)
832 {
833 u64 chattr;
834
835 if (stat->result_mask & STATX_CHANGE_COOKIE) {
836 chattr = stat->change_cookie;
837 if (S_ISREG(stat->mode) &&
838 !(stat->attributes & STATX_ATTR_CHANGE_MONOTONIC)) {
839 chattr += (u64)stat->ctime.tv_sec << 30;
840 chattr += stat->ctime.tv_nsec;
841 }
842 } else {
843 chattr = time_to_chattr(&stat->ctime);
844 }
845 return chattr;
846 }
847