xref: /openbmc/linux/fs/nfsd/nfsfh.c (revision e29dc460)
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 
18 #define NFSDDBG_FACILITY		NFSDDBG_FH
19 
20 
21 /*
22  * our acceptability function.
23  * if NOSUBTREECHECK, accept anything
24  * if not, require that we can walk up to exp->ex_dentry
25  * doing some checks on the 'x' bits
26  */
27 static int nfsd_acceptable(void *expv, struct dentry *dentry)
28 {
29 	struct svc_export *exp = expv;
30 	int rv;
31 	struct dentry *tdentry;
32 	struct dentry *parent;
33 
34 	if (exp->ex_flags & NFSEXP_NOSUBTREECHECK)
35 		return 1;
36 
37 	tdentry = dget(dentry);
38 	while (tdentry != exp->ex_path.dentry && !IS_ROOT(tdentry)) {
39 		/* make sure parents give x permission to user */
40 		int err;
41 		parent = dget_parent(tdentry);
42 		err = inode_permission(d_inode(parent), MAY_EXEC);
43 		if (err < 0) {
44 			dput(parent);
45 			break;
46 		}
47 		dput(tdentry);
48 		tdentry = parent;
49 	}
50 	if (tdentry != exp->ex_path.dentry)
51 		dprintk("nfsd_acceptable failed at %p %pd\n", tdentry, tdentry);
52 	rv = (tdentry == exp->ex_path.dentry);
53 	dput(tdentry);
54 	return rv;
55 }
56 
57 /* Type check. The correct error return for type mismatches does not seem to be
58  * generally agreed upon. SunOS seems to use EISDIR if file isn't S_IFREG; a
59  * comment in the NFSv3 spec says this is incorrect (implementation notes for
60  * the write call).
61  */
62 static inline __be32
63 nfsd_mode_check(struct svc_rqst *rqstp, struct dentry *dentry,
64 		umode_t requested)
65 {
66 	umode_t mode = d_inode(dentry)->i_mode & S_IFMT;
67 
68 	if (requested == 0) /* the caller doesn't care */
69 		return nfs_ok;
70 	if (mode == requested) {
71 		if (mode == S_IFDIR && !d_can_lookup(dentry)) {
72 			WARN_ON_ONCE(1);
73 			return nfserr_notdir;
74 		}
75 		return nfs_ok;
76 	}
77 	/*
78 	 * v4 has an error more specific than err_notdir which we should
79 	 * return in preference to err_notdir:
80 	 */
81 	if (rqstp->rq_vers == 4 && mode == S_IFLNK)
82 		return nfserr_symlink;
83 	if (requested == S_IFDIR)
84 		return nfserr_notdir;
85 	if (mode == S_IFDIR)
86 		return nfserr_isdir;
87 	return nfserr_inval;
88 }
89 
90 static bool nfsd_originating_port_ok(struct svc_rqst *rqstp, int flags)
91 {
92 	if (flags & NFSEXP_INSECURE_PORT)
93 		return true;
94 	/* We don't require gss requests to use low ports: */
95 	if (rqstp->rq_cred.cr_flavor >= RPC_AUTH_GSS)
96 		return true;
97 	return test_bit(RQ_SECURE, &rqstp->rq_flags);
98 }
99 
100 static __be32 nfsd_setuser_and_check_port(struct svc_rqst *rqstp,
101 					  struct svc_export *exp)
102 {
103 	int flags = nfsexp_flags(rqstp, exp);
104 
105 	/* Check if the request originated from a secure port. */
106 	if (!nfsd_originating_port_ok(rqstp, flags)) {
107 		RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
108 		dprintk("nfsd: request from insecure port %s!\n",
109 		        svc_print_addr(rqstp, buf, sizeof(buf)));
110 		return nfserr_perm;
111 	}
112 
113 	/* Set user creds for this exportpoint */
114 	return nfserrno(nfsd_setuser(rqstp, exp));
115 }
116 
117 static inline __be32 check_pseudo_root(struct svc_rqst *rqstp,
118 	struct dentry *dentry, struct svc_export *exp)
119 {
120 	if (!(exp->ex_flags & NFSEXP_V4ROOT))
121 		return nfs_ok;
122 	/*
123 	 * v2/v3 clients have no need for the V4ROOT export--they use
124 	 * the mount protocl instead; also, further V4ROOT checks may be
125 	 * in v4-specific code, in which case v2/v3 clients could bypass
126 	 * them.
127 	 */
128 	if (!nfsd_v4client(rqstp))
129 		return nfserr_stale;
130 	/*
131 	 * We're exposing only the directories and symlinks that have to be
132 	 * traversed on the way to real exports:
133 	 */
134 	if (unlikely(!d_is_dir(dentry) &&
135 		     !d_is_symlink(dentry)))
136 		return nfserr_stale;
137 	/*
138 	 * A pseudoroot export gives permission to access only one
139 	 * single directory; the kernel has to make another upcall
140 	 * before granting access to anything else under it:
141 	 */
142 	if (unlikely(dentry != exp->ex_path.dentry))
143 		return nfserr_stale;
144 	return nfs_ok;
145 }
146 
147 /*
148  * Use the given filehandle to look up the corresponding export and
149  * dentry.  On success, the results are used to set fh_export and
150  * fh_dentry.
151  */
152 static __be32 nfsd_set_fh_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp)
153 {
154 	struct knfsd_fh	*fh = &fhp->fh_handle;
155 	struct fid *fid = NULL, sfid;
156 	struct svc_export *exp;
157 	struct dentry *dentry;
158 	int fileid_type;
159 	int data_left = fh->fh_size/4;
160 	__be32 error;
161 
162 	error = nfserr_stale;
163 	if (rqstp->rq_vers > 2)
164 		error = nfserr_badhandle;
165 	if (rqstp->rq_vers == 4 && fh->fh_size == 0)
166 		return nfserr_nofilehandle;
167 
168 	if (fh->fh_version == 1) {
169 		int len;
170 
171 		if (--data_left < 0)
172 			return error;
173 		if (fh->fh_auth_type != 0)
174 			return error;
175 		len = key_len(fh->fh_fsid_type) / 4;
176 		if (len == 0)
177 			return error;
178 		if  (fh->fh_fsid_type == FSID_MAJOR_MINOR) {
179 			/* deprecated, convert to type 3 */
180 			len = key_len(FSID_ENCODE_DEV)/4;
181 			fh->fh_fsid_type = FSID_ENCODE_DEV;
182 			/*
183 			 * struct knfsd_fh uses host-endian fields, which are
184 			 * sometimes used to hold net-endian values. This
185 			 * confuses sparse, so we must use __force here to
186 			 * keep it from complaining.
187 			 */
188 			fh->fh_fsid[0] = new_encode_dev(MKDEV(ntohl((__force __be32)fh->fh_fsid[0]),
189 							ntohl((__force __be32)fh->fh_fsid[1])));
190 			fh->fh_fsid[1] = fh->fh_fsid[2];
191 		}
192 		data_left -= len;
193 		if (data_left < 0)
194 			return error;
195 		exp = rqst_exp_find(rqstp, fh->fh_fsid_type, fh->fh_fsid);
196 		fid = (struct fid *)(fh->fh_fsid + len);
197 	} else {
198 		__u32 tfh[2];
199 		dev_t xdev;
200 		ino_t xino;
201 
202 		if (fh->fh_size != NFS_FHSIZE)
203 			return error;
204 		/* assume old filehandle format */
205 		xdev = old_decode_dev(fh->ofh_xdev);
206 		xino = u32_to_ino_t(fh->ofh_xino);
207 		mk_fsid(FSID_DEV, tfh, xdev, xino, 0, NULL);
208 		exp = rqst_exp_find(rqstp, FSID_DEV, tfh);
209 	}
210 
211 	error = nfserr_stale;
212 	if (PTR_ERR(exp) == -ENOENT)
213 		return error;
214 
215 	if (IS_ERR(exp))
216 		return nfserrno(PTR_ERR(exp));
217 
218 	if (exp->ex_flags & NFSEXP_NOSUBTREECHECK) {
219 		/* Elevate privileges so that the lack of 'r' or 'x'
220 		 * permission on some parent directory will
221 		 * not stop exportfs_decode_fh from being able
222 		 * to reconnect a directory into the dentry cache.
223 		 * The same problem can affect "SUBTREECHECK" exports,
224 		 * but as nfsd_acceptable depends on correct
225 		 * access control settings being in effect, we cannot
226 		 * fix that case easily.
227 		 */
228 		struct cred *new = prepare_creds();
229 		if (!new) {
230 			error =  nfserrno(-ENOMEM);
231 			goto out;
232 		}
233 		new->cap_effective =
234 			cap_raise_nfsd_set(new->cap_effective,
235 					   new->cap_permitted);
236 		put_cred(override_creds(new));
237 		put_cred(new);
238 	} else {
239 		error = nfsd_setuser_and_check_port(rqstp, exp);
240 		if (error)
241 			goto out;
242 	}
243 
244 	/*
245 	 * Look up the dentry using the NFS file handle.
246 	 */
247 	error = nfserr_stale;
248 	if (rqstp->rq_vers > 2)
249 		error = nfserr_badhandle;
250 
251 	if (fh->fh_version != 1) {
252 		sfid.i32.ino = fh->ofh_ino;
253 		sfid.i32.gen = fh->ofh_generation;
254 		sfid.i32.parent_ino = fh->ofh_dirino;
255 		fid = &sfid;
256 		data_left = 3;
257 		if (fh->ofh_dirino == 0)
258 			fileid_type = FILEID_INO32_GEN;
259 		else
260 			fileid_type = FILEID_INO32_GEN_PARENT;
261 	} else
262 		fileid_type = fh->fh_fileid_type;
263 
264 	if (fileid_type == FILEID_ROOT)
265 		dentry = dget(exp->ex_path.dentry);
266 	else {
267 		dentry = exportfs_decode_fh(exp->ex_path.mnt, fid,
268 				data_left, fileid_type,
269 				nfsd_acceptable, exp);
270 	}
271 	if (dentry == NULL)
272 		goto out;
273 	if (IS_ERR(dentry)) {
274 		if (PTR_ERR(dentry) != -EINVAL)
275 			error = nfserrno(PTR_ERR(dentry));
276 		goto out;
277 	}
278 
279 	if (d_is_dir(dentry) &&
280 			(dentry->d_flags & DCACHE_DISCONNECTED)) {
281 		printk("nfsd: find_fh_dentry returned a DISCONNECTED directory: %pd2\n",
282 				dentry);
283 	}
284 
285 	fhp->fh_dentry = dentry;
286 	fhp->fh_export = exp;
287 	return 0;
288 out:
289 	exp_put(exp);
290 	return error;
291 }
292 
293 /**
294  * fh_verify - filehandle lookup and access checking
295  * @rqstp: pointer to current rpc request
296  * @fhp: filehandle to be verified
297  * @type: expected type of object pointed to by filehandle
298  * @access: type of access needed to object
299  *
300  * Look up a dentry from the on-the-wire filehandle, check the client's
301  * access to the export, and set the current task's credentials.
302  *
303  * Regardless of success or failure of fh_verify(), fh_put() should be
304  * called on @fhp when the caller is finished with the filehandle.
305  *
306  * fh_verify() may be called multiple times on a given filehandle, for
307  * example, when processing an NFSv4 compound.  The first call will look
308  * up a dentry using the on-the-wire filehandle.  Subsequent calls will
309  * skip the lookup and just perform the other checks and possibly change
310  * the current task's credentials.
311  *
312  * @type specifies the type of object expected using one of the S_IF*
313  * constants defined in include/linux/stat.h.  The caller may use zero
314  * to indicate that it doesn't care, or a negative integer to indicate
315  * that it expects something not of the given type.
316  *
317  * @access is formed from the NFSD_MAY_* constants defined in
318  * fs/nfsd/vfs.h.
319  */
320 __be32
321 fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type, int access)
322 {
323 	struct svc_export *exp;
324 	struct dentry	*dentry;
325 	__be32		error;
326 
327 	dprintk("nfsd: fh_verify(%s)\n", SVCFH_fmt(fhp));
328 
329 	if (!fhp->fh_dentry) {
330 		error = nfsd_set_fh_dentry(rqstp, fhp);
331 		if (error)
332 			goto out;
333 	}
334 	dentry = fhp->fh_dentry;
335 	exp = fhp->fh_export;
336 	/*
337 	 * We still have to do all these permission checks, even when
338 	 * fh_dentry is already set:
339 	 * 	- fh_verify may be called multiple times with different
340 	 * 	  "access" arguments (e.g. nfsd_proc_create calls
341 	 * 	  fh_verify(...,NFSD_MAY_EXEC) first, then later (in
342 	 * 	  nfsd_create) calls fh_verify(...,NFSD_MAY_CREATE).
343 	 *	- in the NFSv4 case, the filehandle may have been filled
344 	 *	  in by fh_compose, and given a dentry, but further
345 	 *	  compound operations performed with that filehandle
346 	 *	  still need permissions checks.  In the worst case, a
347 	 *	  mountpoint crossing may have changed the export
348 	 *	  options, and we may now need to use a different uid
349 	 *	  (for example, if different id-squashing options are in
350 	 *	  effect on the new filesystem).
351 	 */
352 	error = check_pseudo_root(rqstp, dentry, exp);
353 	if (error)
354 		goto out;
355 
356 	error = nfsd_setuser_and_check_port(rqstp, exp);
357 	if (error)
358 		goto out;
359 
360 	error = nfsd_mode_check(rqstp, dentry, type);
361 	if (error)
362 		goto out;
363 
364 	/*
365 	 * pseudoflavor restrictions are not enforced on NLM,
366 	 * which clients virtually always use auth_sys for,
367 	 * even while using RPCSEC_GSS for NFS.
368 	 */
369 	if (access & NFSD_MAY_LOCK || access & NFSD_MAY_BYPASS_GSS)
370 		goto skip_pseudoflavor_check;
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 		goto skip_pseudoflavor_check;
379 
380 	error = check_nfsd_access(exp, rqstp);
381 	if (error)
382 		goto out;
383 
384 skip_pseudoflavor_check:
385 	/* Finally, check access permissions. */
386 	error = nfsd_permission(rqstp, exp, dentry, access);
387 
388 	if (error) {
389 		dprintk("fh_verify: %pd2 permission failure, "
390 			"acc=%x, error=%d\n",
391 			dentry,
392 			access, ntohl(error));
393 	}
394 out:
395 	if (error == nfserr_stale)
396 		nfsdstats.fh_stale++;
397 	return error;
398 }
399 
400 
401 /*
402  * Compose a file handle for an NFS reply.
403  *
404  * Note that when first composed, the dentry may not yet have
405  * an inode.  In this case a call to fh_update should be made
406  * before the fh goes out on the wire ...
407  */
408 static void _fh_update(struct svc_fh *fhp, struct svc_export *exp,
409 		struct dentry *dentry)
410 {
411 	if (dentry != exp->ex_path.dentry) {
412 		struct fid *fid = (struct fid *)
413 			(fhp->fh_handle.fh_fsid + fhp->fh_handle.fh_size/4 - 1);
414 		int maxsize = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4;
415 		int subtreecheck = !(exp->ex_flags & NFSEXP_NOSUBTREECHECK);
416 
417 		fhp->fh_handle.fh_fileid_type =
418 			exportfs_encode_fh(dentry, fid, &maxsize, subtreecheck);
419 		fhp->fh_handle.fh_size += maxsize * 4;
420 	} else {
421 		fhp->fh_handle.fh_fileid_type = FILEID_ROOT;
422 	}
423 }
424 
425 /*
426  * for composing old style file handles
427  */
428 static inline void _fh_update_old(struct dentry *dentry,
429 				  struct svc_export *exp,
430 				  struct knfsd_fh *fh)
431 {
432 	fh->ofh_ino = ino_t_to_u32(d_inode(dentry)->i_ino);
433 	fh->ofh_generation = d_inode(dentry)->i_generation;
434 	if (d_is_dir(dentry) ||
435 	    (exp->ex_flags & NFSEXP_NOSUBTREECHECK))
436 		fh->ofh_dirino = 0;
437 }
438 
439 static bool is_root_export(struct svc_export *exp)
440 {
441 	return exp->ex_path.dentry == exp->ex_path.dentry->d_sb->s_root;
442 }
443 
444 static struct super_block *exp_sb(struct svc_export *exp)
445 {
446 	return exp->ex_path.dentry->d_sb;
447 }
448 
449 static bool fsid_type_ok_for_exp(u8 fsid_type, struct svc_export *exp)
450 {
451 	switch (fsid_type) {
452 	case FSID_DEV:
453 		if (!old_valid_dev(exp_sb(exp)->s_dev))
454 			return 0;
455 		/* FALL THROUGH */
456 	case FSID_MAJOR_MINOR:
457 	case FSID_ENCODE_DEV:
458 		return exp_sb(exp)->s_type->fs_flags & FS_REQUIRES_DEV;
459 	case FSID_NUM:
460 		return exp->ex_flags & NFSEXP_FSID;
461 	case FSID_UUID8:
462 	case FSID_UUID16:
463 		if (!is_root_export(exp))
464 			return 0;
465 		/* fall through */
466 	case FSID_UUID4_INUM:
467 	case FSID_UUID16_INUM:
468 		return exp->ex_uuid != NULL;
469 	}
470 	return 1;
471 }
472 
473 
474 static void set_version_and_fsid_type(struct svc_fh *fhp, struct svc_export *exp, struct svc_fh *ref_fh)
475 {
476 	u8 version;
477 	u8 fsid_type;
478 retry:
479 	version = 1;
480 	if (ref_fh && ref_fh->fh_export == exp) {
481 		version = ref_fh->fh_handle.fh_version;
482 		fsid_type = ref_fh->fh_handle.fh_fsid_type;
483 
484 		ref_fh = NULL;
485 
486 		switch (version) {
487 		case 0xca:
488 			fsid_type = FSID_DEV;
489 			break;
490 		case 1:
491 			break;
492 		default:
493 			goto retry;
494 		}
495 
496 		/*
497 		 * As the fsid -> filesystem mapping was guided by
498 		 * user-space, there is no guarantee that the filesystem
499 		 * actually supports that fsid type. If it doesn't we
500 		 * loop around again without ref_fh set.
501 		 */
502 		if (!fsid_type_ok_for_exp(fsid_type, exp))
503 			goto retry;
504 	} else if (exp->ex_flags & NFSEXP_FSID) {
505 		fsid_type = FSID_NUM;
506 	} else if (exp->ex_uuid) {
507 		if (fhp->fh_maxsize >= 64) {
508 			if (is_root_export(exp))
509 				fsid_type = FSID_UUID16;
510 			else
511 				fsid_type = FSID_UUID16_INUM;
512 		} else {
513 			if (is_root_export(exp))
514 				fsid_type = FSID_UUID8;
515 			else
516 				fsid_type = FSID_UUID4_INUM;
517 		}
518 	} else if (!old_valid_dev(exp_sb(exp)->s_dev))
519 		/* for newer device numbers, we must use a newer fsid format */
520 		fsid_type = FSID_ENCODE_DEV;
521 	else
522 		fsid_type = FSID_DEV;
523 	fhp->fh_handle.fh_version = version;
524 	if (version)
525 		fhp->fh_handle.fh_fsid_type = fsid_type;
526 }
527 
528 __be32
529 fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry,
530 	   struct svc_fh *ref_fh)
531 {
532 	/* ref_fh is a reference file handle.
533 	 * if it is non-null and for the same filesystem, then we should compose
534 	 * a filehandle which is of the same version, where possible.
535 	 * Currently, that means that if ref_fh->fh_handle.fh_version == 0xca
536 	 * Then create a 32byte filehandle using nfs_fhbase_old
537 	 *
538 	 */
539 
540 	struct inode * inode = d_inode(dentry);
541 	dev_t ex_dev = exp_sb(exp)->s_dev;
542 
543 	dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %pd2, ino=%ld)\n",
544 		MAJOR(ex_dev), MINOR(ex_dev),
545 		(long) d_inode(exp->ex_path.dentry)->i_ino,
546 		dentry,
547 		(inode ? inode->i_ino : 0));
548 
549 	/* Choose filehandle version and fsid type based on
550 	 * the reference filehandle (if it is in the same export)
551 	 * or the export options.
552 	 */
553 	set_version_and_fsid_type(fhp, exp, ref_fh);
554 
555 	if (ref_fh == fhp)
556 		fh_put(ref_fh);
557 
558 	if (fhp->fh_locked || fhp->fh_dentry) {
559 		printk(KERN_ERR "fh_compose: fh %pd2 not initialized!\n",
560 		       dentry);
561 	}
562 	if (fhp->fh_maxsize < NFS_FHSIZE)
563 		printk(KERN_ERR "fh_compose: called with maxsize %d! %pd2\n",
564 		       fhp->fh_maxsize,
565 		       dentry);
566 
567 	fhp->fh_dentry = dget(dentry); /* our internal copy */
568 	fhp->fh_export = exp_get(exp);
569 
570 	if (fhp->fh_handle.fh_version == 0xca) {
571 		/* old style filehandle please */
572 		memset(&fhp->fh_handle.fh_base, 0, NFS_FHSIZE);
573 		fhp->fh_handle.fh_size = NFS_FHSIZE;
574 		fhp->fh_handle.ofh_dcookie = 0xfeebbaca;
575 		fhp->fh_handle.ofh_dev =  old_encode_dev(ex_dev);
576 		fhp->fh_handle.ofh_xdev = fhp->fh_handle.ofh_dev;
577 		fhp->fh_handle.ofh_xino =
578 			ino_t_to_u32(d_inode(exp->ex_path.dentry)->i_ino);
579 		fhp->fh_handle.ofh_dirino = ino_t_to_u32(parent_ino(dentry));
580 		if (inode)
581 			_fh_update_old(dentry, exp, &fhp->fh_handle);
582 	} else {
583 		fhp->fh_handle.fh_size =
584 			key_len(fhp->fh_handle.fh_fsid_type) + 4;
585 		fhp->fh_handle.fh_auth_type = 0;
586 
587 		mk_fsid(fhp->fh_handle.fh_fsid_type,
588 			fhp->fh_handle.fh_fsid,
589 			ex_dev,
590 			d_inode(exp->ex_path.dentry)->i_ino,
591 			exp->ex_fsid, exp->ex_uuid);
592 
593 		if (inode)
594 			_fh_update(fhp, exp, dentry);
595 		if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID) {
596 			fh_put(fhp);
597 			return nfserr_opnotsupp;
598 		}
599 	}
600 
601 	return 0;
602 }
603 
604 /*
605  * Update file handle information after changing a dentry.
606  * This is only called by nfsd_create, nfsd_create_v3 and nfsd_proc_create
607  */
608 __be32
609 fh_update(struct svc_fh *fhp)
610 {
611 	struct dentry *dentry;
612 
613 	if (!fhp->fh_dentry)
614 		goto out_bad;
615 
616 	dentry = fhp->fh_dentry;
617 	if (d_really_is_negative(dentry))
618 		goto out_negative;
619 	if (fhp->fh_handle.fh_version != 1) {
620 		_fh_update_old(dentry, fhp->fh_export, &fhp->fh_handle);
621 	} else {
622 		if (fhp->fh_handle.fh_fileid_type != FILEID_ROOT)
623 			return 0;
624 
625 		_fh_update(fhp, fhp->fh_export, dentry);
626 		if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID)
627 			return nfserr_opnotsupp;
628 	}
629 	return 0;
630 out_bad:
631 	printk(KERN_ERR "fh_update: fh not verified!\n");
632 	return nfserr_serverfault;
633 out_negative:
634 	printk(KERN_ERR "fh_update: %pd2 still negative!\n",
635 		dentry);
636 	return nfserr_serverfault;
637 }
638 
639 /*
640  * Release a file handle.
641  */
642 void
643 fh_put(struct svc_fh *fhp)
644 {
645 	struct dentry * dentry = fhp->fh_dentry;
646 	struct svc_export * exp = fhp->fh_export;
647 	if (dentry) {
648 		fh_unlock(fhp);
649 		fhp->fh_dentry = NULL;
650 		dput(dentry);
651 		fh_clear_wcc(fhp);
652 	}
653 	fh_drop_write(fhp);
654 	if (exp) {
655 		exp_put(exp);
656 		fhp->fh_export = NULL;
657 	}
658 	return;
659 }
660 
661 /*
662  * Shorthand for dprintk()'s
663  */
664 char * SVCFH_fmt(struct svc_fh *fhp)
665 {
666 	struct knfsd_fh *fh = &fhp->fh_handle;
667 
668 	static char buf[80];
669 	sprintf(buf, "%d: %08x %08x %08x %08x %08x %08x",
670 		fh->fh_size,
671 		fh->fh_base.fh_pad[0],
672 		fh->fh_base.fh_pad[1],
673 		fh->fh_base.fh_pad[2],
674 		fh->fh_base.fh_pad[3],
675 		fh->fh_base.fh_pad[4],
676 		fh->fh_base.fh_pad[5]);
677 	return buf;
678 }
679 
680 enum fsid_source fsid_source(struct svc_fh *fhp)
681 {
682 	if (fhp->fh_handle.fh_version != 1)
683 		return FSIDSOURCE_DEV;
684 	switch(fhp->fh_handle.fh_fsid_type) {
685 	case FSID_DEV:
686 	case FSID_ENCODE_DEV:
687 	case FSID_MAJOR_MINOR:
688 		if (exp_sb(fhp->fh_export)->s_type->fs_flags & FS_REQUIRES_DEV)
689 			return FSIDSOURCE_DEV;
690 		break;
691 	case FSID_NUM:
692 		if (fhp->fh_export->ex_flags & NFSEXP_FSID)
693 			return FSIDSOURCE_FSID;
694 		break;
695 	default:
696 		break;
697 	}
698 	/* either a UUID type filehandle, or the filehandle doesn't
699 	 * match the export.
700 	 */
701 	if (fhp->fh_export->ex_flags & NFSEXP_FSID)
702 		return FSIDSOURCE_FSID;
703 	if (fhp->fh_export->ex_uuid)
704 		return FSIDSOURCE_UUID;
705 	return FSIDSOURCE_DEV;
706 }
707