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 */
 28static 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 */
 64static inline __be32
 65nfsd_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
 92static 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
102static __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
119static 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 */
154static __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;
295out:
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
328fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type, int access)
329{
330	struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
331	struct svc_export *exp = NULL;
332	struct dentry	*dentry;
333	__be32		error;
334
 
 
335	if (!fhp->fh_dentry) {
336		error = nfsd_set_fh_dentry(rqstp, fhp);
337		if (error)
338			goto out;
339	}
340	dentry = fhp->fh_dentry;
341	exp = fhp->fh_export;
342
343	trace_nfsd_fh_verify(rqstp, fhp, type, access);
344
345	/*
346	 * We still have to do all these permission checks, even when
347	 * fh_dentry is already set:
348	 * 	- fh_verify may be called multiple times with different
349	 * 	  "access" arguments (e.g. nfsd_proc_create calls
350	 * 	  fh_verify(...,NFSD_MAY_EXEC) first, then later (in
351	 * 	  nfsd_create) calls fh_verify(...,NFSD_MAY_CREATE).
352	 *	- in the NFSv4 case, the filehandle may have been filled
353	 *	  in by fh_compose, and given a dentry, but further
354	 *	  compound operations performed with that filehandle
355	 *	  still need permissions checks.  In the worst case, a
356	 *	  mountpoint crossing may have changed the export
357	 *	  options, and we may now need to use a different uid
358	 *	  (for example, if different id-squashing options are in
359	 *	  effect on the new filesystem).
360	 */
361	error = check_pseudo_root(rqstp, dentry, exp);
362	if (error)
363		goto out;
364
365	error = nfsd_setuser_and_check_port(rqstp, exp);
366	if (error)
367		goto out;
368
369	error = nfsd_mode_check(rqstp, dentry, type);
370	if (error)
371		goto out;
372
373	/*
374	 * pseudoflavor restrictions are not enforced on NLM,
375	 * which clients virtually always use auth_sys for,
376	 * even while using RPCSEC_GSS for NFS.
377	 */
378	if (access & NFSD_MAY_LOCK || access & NFSD_MAY_BYPASS_GSS)
379		goto skip_pseudoflavor_check;
380	/*
381	 * Clients may expect to be able to use auth_sys during mount,
382	 * even if they use gss for everything else; see section 2.3.2
383	 * of rfc 2623.
384	 */
385	if (access & NFSD_MAY_BYPASS_GSS_ON_ROOT
386			&& exp->ex_path.dentry == dentry)
387		goto skip_pseudoflavor_check;
388
389	error = check_nfsd_access(exp, rqstp);
390	if (error)
391		goto out;
392
393skip_pseudoflavor_check:
394	/* Finally, check access permissions. */
395	error = nfsd_permission(rqstp, exp, dentry, access);
 
 
 
 
 
 
 
396out:
397	trace_nfsd_fh_verify_err(rqstp, fhp, type, access, error);
398	if (error == nfserr_stale)
399		nfsd_stats_fh_stale_inc(nn, exp);
400	return error;
401}
402
403
404/*
405 * Compose a file handle for an NFS reply.
406 *
407 * Note that when first composed, the dentry may not yet have
408 * an inode.  In this case a call to fh_update should be made
409 * before the fh goes out on the wire ...
410 */
411static void _fh_update(struct svc_fh *fhp, struct svc_export *exp,
412		struct dentry *dentry)
413{
414	if (dentry != exp->ex_path.dentry) {
415		struct fid *fid = (struct fid *)
416			(fhp->fh_handle.fh_fsid + fhp->fh_handle.fh_size/4 - 1);
417		int maxsize = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4;
418		int fh_flags = (exp->ex_flags & NFSEXP_NOSUBTREECHECK) ? 0 :
419				EXPORT_FH_CONNECTABLE;
420		int fileid_type =
421			exportfs_encode_fh(dentry, fid, &maxsize, fh_flags);
422
423		fhp->fh_handle.fh_fileid_type =
424			fileid_type > 0 ? fileid_type : FILEID_INVALID;
425		fhp->fh_handle.fh_size += maxsize * 4;
426	} else {
427		fhp->fh_handle.fh_fileid_type = FILEID_ROOT;
428	}
429}
430
 
 
 
 
 
 
 
 
 
 
 
 
 
 
431static bool is_root_export(struct svc_export *exp)
432{
433	return exp->ex_path.dentry == exp->ex_path.dentry->d_sb->s_root;
434}
435
436static struct super_block *exp_sb(struct svc_export *exp)
437{
438	return exp->ex_path.dentry->d_sb;
439}
440
441static bool fsid_type_ok_for_exp(u8 fsid_type, struct svc_export *exp)
442{
443	switch (fsid_type) {
444	case FSID_DEV:
445		if (!old_valid_dev(exp_sb(exp)->s_dev))
446			return false;
447		fallthrough;
448	case FSID_MAJOR_MINOR:
449	case FSID_ENCODE_DEV:
450		return exp_sb(exp)->s_type->fs_flags & FS_REQUIRES_DEV;
451	case FSID_NUM:
452		return exp->ex_flags & NFSEXP_FSID;
453	case FSID_UUID8:
454	case FSID_UUID16:
455		if (!is_root_export(exp))
456			return false;
457		fallthrough;
458	case FSID_UUID4_INUM:
459	case FSID_UUID16_INUM:
460		return exp->ex_uuid != NULL;
461	}
462	return true;
463}
464
465
466static void set_version_and_fsid_type(struct svc_fh *fhp, struct svc_export *exp, struct svc_fh *ref_fh)
467{
468	u8 version;
469	u8 fsid_type;
470retry:
471	version = 1;
472	if (ref_fh && ref_fh->fh_export == exp) {
473		version = ref_fh->fh_handle.fh_version;
474		fsid_type = ref_fh->fh_handle.fh_fsid_type;
475
476		ref_fh = NULL;
477
478		switch (version) {
479		case 0xca:
480			fsid_type = FSID_DEV;
481			break;
482		case 1:
483			break;
484		default:
485			goto retry;
486		}
487
488		/*
489		 * As the fsid -> filesystem mapping was guided by
490		 * user-space, there is no guarantee that the filesystem
491		 * actually supports that fsid type. If it doesn't we
492		 * loop around again without ref_fh set.
493		 */
494		if (!fsid_type_ok_for_exp(fsid_type, exp))
495			goto retry;
496	} else if (exp->ex_flags & NFSEXP_FSID) {
497		fsid_type = FSID_NUM;
498	} else if (exp->ex_uuid) {
499		if (fhp->fh_maxsize >= 64) {
500			if (is_root_export(exp))
501				fsid_type = FSID_UUID16;
502			else
503				fsid_type = FSID_UUID16_INUM;
504		} else {
505			if (is_root_export(exp))
506				fsid_type = FSID_UUID8;
507			else
508				fsid_type = FSID_UUID4_INUM;
509		}
510	} else if (!old_valid_dev(exp_sb(exp)->s_dev))
511		/* for newer device numbers, we must use a newer fsid format */
512		fsid_type = FSID_ENCODE_DEV;
513	else
514		fsid_type = FSID_DEV;
515	fhp->fh_handle.fh_version = version;
516	if (version)
517		fhp->fh_handle.fh_fsid_type = fsid_type;
518}
519
520__be32
521fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry,
522	   struct svc_fh *ref_fh)
523{
524	/* ref_fh is a reference file handle.
525	 * if it is non-null and for the same filesystem, then we should compose
526	 * a filehandle which is of the same version, where possible.
 
 
 
527	 */
528
529	struct inode * inode = d_inode(dentry);
530	dev_t ex_dev = exp_sb(exp)->s_dev;
531
532	dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %pd2, ino=%ld)\n",
533		MAJOR(ex_dev), MINOR(ex_dev),
534		(long) d_inode(exp->ex_path.dentry)->i_ino,
535		dentry,
536		(inode ? inode->i_ino : 0));
537
538	/* Choose filehandle version and fsid type based on
539	 * the reference filehandle (if it is in the same export)
540	 * or the export options.
541	 */
542	set_version_and_fsid_type(fhp, exp, ref_fh);
543
544	/* If we have a ref_fh, then copy the fh_no_wcc setting from it. */
545	fhp->fh_no_wcc = ref_fh ? ref_fh->fh_no_wcc : false;
546
547	if (ref_fh == fhp)
548		fh_put(ref_fh);
549
550	if (fhp->fh_dentry) {
551		printk(KERN_ERR "fh_compose: fh %pd2 not initialized!\n",
552		       dentry);
553	}
554	if (fhp->fh_maxsize < NFS_FHSIZE)
555		printk(KERN_ERR "fh_compose: called with maxsize %d! %pd2\n",
556		       fhp->fh_maxsize,
557		       dentry);
558
559	fhp->fh_dentry = dget(dentry); /* our internal copy */
560	fhp->fh_export = exp_get(exp);
561
562	fhp->fh_handle.fh_size =
563		key_len(fhp->fh_handle.fh_fsid_type) + 4;
564	fhp->fh_handle.fh_auth_type = 0;
565
566	mk_fsid(fhp->fh_handle.fh_fsid_type,
567		fhp->fh_handle.fh_fsid,
568		ex_dev,
569		d_inode(exp->ex_path.dentry)->i_ino,
570		exp->ex_fsid, exp->ex_uuid);
571
572	if (inode)
573		_fh_update(fhp, exp, dentry);
574	if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID) {
575		fh_put(fhp);
576		return nfserr_opnotsupp;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
577	}
578
579	return 0;
580}
581
582/*
583 * Update file handle information after changing a dentry.
584 * This is only called by nfsd_create, nfsd_create_v3 and nfsd_proc_create
585 */
586__be32
587fh_update(struct svc_fh *fhp)
588{
589	struct dentry *dentry;
590
591	if (!fhp->fh_dentry)
592		goto out_bad;
593
594	dentry = fhp->fh_dentry;
595	if (d_really_is_negative(dentry))
596		goto out_negative;
597	if (fhp->fh_handle.fh_fileid_type != FILEID_ROOT)
598		return 0;
 
 
 
599
600	_fh_update(fhp, fhp->fh_export, dentry);
601	if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID)
602		return nfserr_opnotsupp;
 
603	return 0;
604out_bad:
605	printk(KERN_ERR "fh_update: fh not verified!\n");
606	return nfserr_serverfault;
607out_negative:
608	printk(KERN_ERR "fh_update: %pd2 still negative!\n",
609		dentry);
610	return nfserr_serverfault;
611}
612
613/**
614 * fh_fill_pre_attrs - Fill in pre-op attributes
615 * @fhp: file handle to be updated
616 *
617 */
618__be32 __must_check fh_fill_pre_attrs(struct svc_fh *fhp)
619{
620	bool v4 = (fhp->fh_maxsize == NFS4_FHSIZE);
621	struct inode *inode;
622	struct kstat stat;
623	__be32 err;
624
625	if (fhp->fh_no_wcc || fhp->fh_pre_saved)
626		return nfs_ok;
627
628	inode = d_inode(fhp->fh_dentry);
629	err = fh_getattr(fhp, &stat);
630	if (err)
631		return err;
632
633	if (v4)
634		fhp->fh_pre_change = nfsd4_change_attribute(&stat, inode);
635
636	fhp->fh_pre_mtime = stat.mtime;
637	fhp->fh_pre_ctime = stat.ctime;
638	fhp->fh_pre_size  = stat.size;
639	fhp->fh_pre_saved = true;
640	return nfs_ok;
641}
642
643/**
644 * fh_fill_post_attrs - Fill in post-op attributes
645 * @fhp: file handle to be updated
646 *
647 */
648__be32 fh_fill_post_attrs(struct svc_fh *fhp)
649{
650	bool v4 = (fhp->fh_maxsize == NFS4_FHSIZE);
651	struct inode *inode = d_inode(fhp->fh_dentry);
652	__be32 err;
653
654	if (fhp->fh_no_wcc)
655		return nfs_ok;
656
657	if (fhp->fh_post_saved)
658		printk("nfsd: inode locked twice during operation.\n");
659
660	err = fh_getattr(fhp, &fhp->fh_post_attr);
661	if (err)
662		return err;
663
664	fhp->fh_post_saved = true;
665	if (v4)
666		fhp->fh_post_change =
667			nfsd4_change_attribute(&fhp->fh_post_attr, inode);
668	return nfs_ok;
669}
670
671/**
672 * fh_fill_both_attrs - Fill pre-op and post-op attributes
673 * @fhp: file handle to be updated
674 *
675 * This is used when the directory wasn't changed, but wcc attributes
676 * are needed anyway.
677 */
678__be32 __must_check fh_fill_both_attrs(struct svc_fh *fhp)
679{
680	__be32 err;
681
682	err = fh_fill_post_attrs(fhp);
683	if (err)
684		return err;
685
686	fhp->fh_pre_change = fhp->fh_post_change;
687	fhp->fh_pre_mtime = fhp->fh_post_attr.mtime;
688	fhp->fh_pre_ctime = fhp->fh_post_attr.ctime;
689	fhp->fh_pre_size = fhp->fh_post_attr.size;
690	fhp->fh_pre_saved = true;
691	return nfs_ok;
692}
693
694/*
695 * Release a file handle.
696 */
697void
698fh_put(struct svc_fh *fhp)
699{
700	struct dentry * dentry = fhp->fh_dentry;
701	struct svc_export * exp = fhp->fh_export;
702	if (dentry) {
 
703		fhp->fh_dentry = NULL;
704		dput(dentry);
705		fh_clear_pre_post_attrs(fhp);
706	}
707	fh_drop_write(fhp);
708	if (exp) {
709		exp_put(exp);
710		fhp->fh_export = NULL;
711	}
712	fhp->fh_no_wcc = false;
713	return;
714}
715
716/*
717 * Shorthand for dprintk()'s
718 */
719char * SVCFH_fmt(struct svc_fh *fhp)
720{
721	struct knfsd_fh *fh = &fhp->fh_handle;
722	static char buf[2+1+1+64*3+1];
723
724	if (fh->fh_size < 0 || fh->fh_size> 64)
725		return "bad-fh";
726	sprintf(buf, "%d: %*ph", fh->fh_size, fh->fh_size, fh->fh_raw);
 
 
 
 
 
 
727	return buf;
728}
729
730enum fsid_source fsid_source(const struct svc_fh *fhp)
731{
732	if (fhp->fh_handle.fh_version != 1)
733		return FSIDSOURCE_DEV;
734	switch(fhp->fh_handle.fh_fsid_type) {
735	case FSID_DEV:
736	case FSID_ENCODE_DEV:
737	case FSID_MAJOR_MINOR:
738		if (exp_sb(fhp->fh_export)->s_type->fs_flags & FS_REQUIRES_DEV)
739			return FSIDSOURCE_DEV;
740		break;
741	case FSID_NUM:
742		if (fhp->fh_export->ex_flags & NFSEXP_FSID)
743			return FSIDSOURCE_FSID;
744		break;
745	default:
746		break;
747	}
748	/* either a UUID type filehandle, or the filehandle doesn't
749	 * match the export.
750	 */
751	if (fhp->fh_export->ex_flags & NFSEXP_FSID)
752		return FSIDSOURCE_FSID;
753	if (fhp->fh_export->ex_uuid)
754		return FSIDSOURCE_UUID;
755	return FSIDSOURCE_DEV;
756}
757
758/*
759 * We could use i_version alone as the change attribute.  However, i_version
760 * can go backwards on a regular file after an unclean shutdown.  On its own
761 * that doesn't necessarily cause a problem, but if i_version goes backwards
762 * and then is incremented again it could reuse a value that was previously
763 * used before boot, and a client who queried the two values might incorrectly
764 * assume nothing changed.
765 *
766 * By using both ctime and the i_version counter we guarantee that as long as
767 * time doesn't go backwards we never reuse an old value. If the filesystem
768 * advertises STATX_ATTR_CHANGE_MONOTONIC, then this mitigation is not
769 * needed.
770 *
771 * We only need to do this for regular files as well. For directories, we
772 * assume that the new change attr is always logged to stable storage in some
773 * fashion before the results can be seen.
774 */
775u64 nfsd4_change_attribute(const struct kstat *stat, const struct inode *inode)
776{
777	u64 chattr;
778
779	if (stat->result_mask & STATX_CHANGE_COOKIE) {
780		chattr = stat->change_cookie;
781		if (S_ISREG(inode->i_mode) &&
782		    !(stat->attributes & STATX_ATTR_CHANGE_MONOTONIC)) {
783			chattr += (u64)stat->ctime.tv_sec << 30;
784			chattr += stat->ctime.tv_nsec;
785		}
786	} else {
787		chattr = time_to_chattr(&stat->ctime);
788	}
789	return chattr;
790}