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