nfsfh.c

  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 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
 90static 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
102static __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
118static 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 */
145static __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	switch (fhp->fh_maxsize) {
273	case NFS4_FHSIZE:
274		if (dentry->d_sb->s_export_op->flags & EXPORT_OP_NOATOMIC_ATTR)
275			fhp->fh_no_atomic_attr = true;
276		fhp->fh_64bit_cookies = true;
277		break;
278	case NFS3_FHSIZE:
279		if (dentry->d_sb->s_export_op->flags & EXPORT_OP_NOWCC)
280			fhp->fh_no_wcc = true;
281		fhp->fh_64bit_cookies = true;
282		if (exp->ex_flags & NFSEXP_V4ROOT)
283			goto out;
284		break;
285	case NFS_FHSIZE:
286		fhp->fh_no_wcc = true;
287		if (EX_WGATHER(exp))
288			fhp->fh_use_wgather = true;
289		if (exp->ex_flags & NFSEXP_V4ROOT)
290			goto out;
291	}
292
293	fhp->fh_dentry = dentry;
294	fhp->fh_export = exp;
295
296	return 0;
297out:
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 */
315static __be32
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	/*
368	 * If rqstp is NULL, this is a LOCALIO request which will only
369	 * ever use a filehandle/credential pair for which access has
370	 * been affirmed (by ACCESS or OPEN NFS requests) over the
371	 * wire.  Skip both the xprtsec policy and the security flavor
372	 * checks.
373	 */
374	if (!rqstp)
375		goto check_permissions;
376
377	if ((access & NFSD_MAY_NLM) && (exp->ex_flags & NFSEXP_NOAUTHNLM))
378		/* NLM is allowed to fully bypass authentication */
379		goto out;
380
381	/*
382	 * NLM is allowed to bypass the xprtsec policy check because lockd
383	 * doesn't support xprtsec.
384	 */
385	if (!(access & NFSD_MAY_NLM)) {
386		error = check_xprtsec_policy(exp, rqstp);
387		if (error)
388			goto out;
389	}
390
391	if (access & NFSD_MAY_BYPASS_GSS)
392		may_bypass_gss = true;
393	/*
394	 * Clients may expect to be able to use auth_sys during mount,
395	 * even if they use gss for everything else; see section 2.3.2
396	 * of rfc 2623.
397	 */
398	if (access & NFSD_MAY_BYPASS_GSS_ON_ROOT
399			&& exp->ex_path.dentry == dentry)
400		may_bypass_gss = true;
401
402	error = check_security_flavor(exp, rqstp, may_bypass_gss);
403	if (error)
404		goto out;
405
406	svc_xprt_set_valid(rqstp->rq_xprt);
407
408check_permissions:
409	/* Finally, check access permissions. */
410	error = nfsd_permission(cred, exp, dentry, access);
411out:
412	trace_nfsd_fh_verify_err(rqstp, fhp, type, access, error);
413	if (error == nfserr_stale)
414		nfsd_stats_fh_stale_inc(nn, exp);
415	return error;
416}
417
418/**
419 * fh_verify_local - filehandle lookup and access checking
420 * @net: net namespace in which to perform the export lookup
421 * @cred: RPC user credential
422 * @client: RPC auth domain
423 * @fhp: filehandle to be verified
424 * @type: expected type of object pointed to by filehandle
425 * @access: type of access needed to object
426 *
427 * This API can be used by callers who do not have an RPC
428 * transaction context (ie are not running in an nfsd thread).
429 *
430 * See fh_verify() for further descriptions of @fhp, @type, and @access.
431 */
432__be32
433fh_verify_local(struct net *net, struct svc_cred *cred,
434		struct auth_domain *client, struct svc_fh *fhp,
435		umode_t type, int access)
436{
437	return __fh_verify(NULL, net, cred, client, NULL,
438			   fhp, type, access);
439}
440
441/**
442 * fh_verify - filehandle lookup and access checking
443 * @rqstp: pointer to current rpc request
444 * @fhp: filehandle to be verified
445 * @type: expected type of object pointed to by filehandle
446 * @access: type of access needed to object
447 *
448 * Look up a dentry from the on-the-wire filehandle, check the client's
449 * access to the export, and set the current task's credentials.
450 *
451 * Regardless of success or failure of fh_verify(), fh_put() should be
452 * called on @fhp when the caller is finished with the filehandle.
453 *
454 * fh_verify() may be called multiple times on a given filehandle, for
455 * example, when processing an NFSv4 compound.  The first call will look
456 * up a dentry using the on-the-wire filehandle.  Subsequent calls will
457 * skip the lookup and just perform the other checks and possibly change
458 * the current task's credentials.
459 *
460 * @type specifies the type of object expected using one of the S_IF*
461 * constants defined in include/linux/stat.h.  The caller may use zero
462 * to indicate that it doesn't care, or a negative integer to indicate
463 * that it expects something not of the given type.
464 *
465 * @access is formed from the NFSD_MAY_* constants defined in
466 * fs/nfsd/vfs.h.
467 */
468__be32
469fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type, int access)
470{
471	return __fh_verify(rqstp, SVC_NET(rqstp), &rqstp->rq_cred,
472			   rqstp->rq_client, rqstp->rq_gssclient,
473			   fhp, type, access);
474}
475
476/*
477 * Compose a file handle for an NFS reply.
478 *
479 * Note that when first composed, the dentry may not yet have
480 * an inode.  In this case a call to fh_update should be made
481 * before the fh goes out on the wire ...
482 */
483static void _fh_update(struct svc_fh *fhp, struct svc_export *exp,
484		struct dentry *dentry)
485{
486	if (dentry != exp->ex_path.dentry) {
487		struct fid *fid = (struct fid *)
488			(fh_fsid(&fhp->fh_handle) + fhp->fh_handle.fh_size/4 - 1);
489		int maxsize = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4;
490		int fh_flags = (exp->ex_flags & NFSEXP_NOSUBTREECHECK) ? 0 :
491				EXPORT_FH_CONNECTABLE;
492		int fileid_type =
493			exportfs_encode_fh(dentry, fid, &maxsize, fh_flags);
494
495		fhp->fh_handle.fh_fileid_type =
496			fileid_type > 0 ? fileid_type : FILEID_INVALID;
497		fhp->fh_handle.fh_size += maxsize * 4;
498	} else {
499		fhp->fh_handle.fh_fileid_type = FILEID_ROOT;
500	}
501}
502
503static bool is_root_export(struct svc_export *exp)
504{
505	return exp->ex_path.dentry == exp->ex_path.dentry->d_sb->s_root;
506}
507
508static struct super_block *exp_sb(struct svc_export *exp)
509{
510	return exp->ex_path.dentry->d_sb;
511}
512
513static bool fsid_type_ok_for_exp(u8 fsid_type, struct svc_export *exp)
514{
515	switch (fsid_type) {
516	case FSID_DEV:
517		if (!old_valid_dev(exp_sb(exp)->s_dev))
518			return false;
519		fallthrough;
520	case FSID_MAJOR_MINOR:
521	case FSID_ENCODE_DEV:
522		return exp_sb(exp)->s_type->fs_flags & FS_REQUIRES_DEV;
523	case FSID_NUM:
524		return exp->ex_flags & NFSEXP_FSID;
525	case FSID_UUID8:
526	case FSID_UUID16:
527		if (!is_root_export(exp))
528			return false;
529		fallthrough;
530	case FSID_UUID4_INUM:
531	case FSID_UUID16_INUM:
532		return exp->ex_uuid != NULL;
533	}
534	return true;
535}
536
537
538static void set_version_and_fsid_type(struct svc_fh *fhp, struct svc_export *exp, struct svc_fh *ref_fh)
539{
540	u8 version;
541	u8 fsid_type;
542retry:
543	version = 1;
544	if (ref_fh && ref_fh->fh_export == exp) {
545		version = ref_fh->fh_handle.fh_version;
546		fsid_type = ref_fh->fh_handle.fh_fsid_type;
547
548		ref_fh = NULL;
549
550		switch (version) {
551		case 0xca:
552			fsid_type = FSID_DEV;
553			break;
554		case 1:
555			break;
556		default:
557			goto retry;
558		}
559
560		/*
561		 * As the fsid -> filesystem mapping was guided by
562		 * user-space, there is no guarantee that the filesystem
563		 * actually supports that fsid type. If it doesn't we
564		 * loop around again without ref_fh set.
565		 */
566		if (!fsid_type_ok_for_exp(fsid_type, exp))
567			goto retry;
568	} else if (exp->ex_flags & NFSEXP_FSID) {
569		fsid_type = FSID_NUM;
570	} else if (exp->ex_uuid) {
571		if (fhp->fh_maxsize >= 64) {
572			if (is_root_export(exp))
573				fsid_type = FSID_UUID16;
574			else
575				fsid_type = FSID_UUID16_INUM;
576		} else {
577			if (is_root_export(exp))
578				fsid_type = FSID_UUID8;
579			else
580				fsid_type = FSID_UUID4_INUM;
581		}
582	} else if (!old_valid_dev(exp_sb(exp)->s_dev))
583		/* for newer device numbers, we must use a newer fsid format */
584		fsid_type = FSID_ENCODE_DEV;
585	else
586		fsid_type = FSID_DEV;
587	fhp->fh_handle.fh_version = version;
588	if (version)
589		fhp->fh_handle.fh_fsid_type = fsid_type;
590}
591
592__be32
593fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry,
594	   struct svc_fh *ref_fh)
595{
596	/* ref_fh is a reference file handle.
597	 * if it is non-null and for the same filesystem, then we should compose
598	 * a filehandle which is of the same version, where possible.
599	 */
600
601	struct inode * inode = d_inode(dentry);
602	dev_t ex_dev = exp_sb(exp)->s_dev;
603
604	dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %pd2, ino=%ld)\n",
605		MAJOR(ex_dev), MINOR(ex_dev),
606		(long) d_inode(exp->ex_path.dentry)->i_ino,
607		dentry,
608		(inode ? inode->i_ino : 0));
609
610	/* Choose filehandle version and fsid type based on
611	 * the reference filehandle (if it is in the same export)
612	 * or the export options.
613	 */
614	set_version_and_fsid_type(fhp, exp, ref_fh);
615
616	/* If we have a ref_fh, then copy the fh_no_wcc setting from it. */
617	fhp->fh_no_wcc = ref_fh ? ref_fh->fh_no_wcc : false;
618
619	if (ref_fh == fhp)
620		fh_put(ref_fh);
621
622	if (fhp->fh_dentry) {
623		printk(KERN_ERR "fh_compose: fh %pd2 not initialized!\n",
624		       dentry);
625	}
626	if (fhp->fh_maxsize < NFS_FHSIZE)
627		printk(KERN_ERR "fh_compose: called with maxsize %d! %pd2\n",
628		       fhp->fh_maxsize,
629		       dentry);
630
631	fhp->fh_dentry = dget(dentry); /* our internal copy */
632	fhp->fh_export = exp_get(exp);
633
634	fhp->fh_handle.fh_size =
635		key_len(fhp->fh_handle.fh_fsid_type) + 4;
636	fhp->fh_handle.fh_auth_type = 0;
637
638	mk_fsid(fhp->fh_handle.fh_fsid_type,
639		fh_fsid(&fhp->fh_handle),
640		ex_dev,
641		d_inode(exp->ex_path.dentry)->i_ino,
642		exp->ex_fsid, exp->ex_uuid);
643
644	if (inode)
645		_fh_update(fhp, exp, dentry);
646	if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID) {
647		fh_put(fhp);
648		return nfserr_stale;
649	}
650
651	return 0;
652}
653
654/*
655 * Update file handle information after changing a dentry.
656 * This is only called by nfsd_create, nfsd_create_v3 and nfsd_proc_create
657 */
658__be32
659fh_update(struct svc_fh *fhp)
660{
661	struct dentry *dentry;
662
663	if (!fhp->fh_dentry)
664		goto out_bad;
665
666	dentry = fhp->fh_dentry;
667	if (d_really_is_negative(dentry))
668		goto out_negative;
669	if (fhp->fh_handle.fh_fileid_type != FILEID_ROOT)
670		return 0;
671
672	_fh_update(fhp, fhp->fh_export, dentry);
673	if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID)
674		return nfserr_stale;
675	return 0;
676out_bad:
677	printk(KERN_ERR "fh_update: fh not verified!\n");
678	return nfserr_serverfault;
679out_negative:
680	printk(KERN_ERR "fh_update: %pd2 still negative!\n",
681		dentry);
682	return nfserr_serverfault;
683}
684
685/**
686 * fh_getattr - Retrieve attributes on a local file
687 * @fhp: File handle of target file
688 * @stat: Caller-supplied kstat buffer to be filled in
689 *
690 * Returns nfs_ok on success, otherwise an NFS status code is
691 * returned.
692 */
693__be32 fh_getattr(const struct svc_fh *fhp, struct kstat *stat)
694{
695	struct path p = {
696		.mnt		= fhp->fh_export->ex_path.mnt,
697		.dentry		= fhp->fh_dentry,
698	};
699	struct inode *inode = d_inode(p.dentry);
700	u32 request_mask = STATX_BASIC_STATS;
701
702	if (S_ISREG(inode->i_mode))
703		request_mask |= (STATX_DIOALIGN | STATX_DIO_READ_ALIGN);
704
705	if (fhp->fh_maxsize == NFS4_FHSIZE)
706		request_mask |= (STATX_BTIME | STATX_CHANGE_COOKIE);
707
708	return nfserrno(vfs_getattr(&p, stat, request_mask,
709				    AT_STATX_SYNC_AS_STAT));
710}
711
712/**
713 * fh_fill_pre_attrs - Fill in pre-op attributes
714 * @fhp: file handle to be updated
715 *
716 */
717__be32 __must_check fh_fill_pre_attrs(struct svc_fh *fhp)
718{
719	bool v4 = (fhp->fh_maxsize == NFS4_FHSIZE);
720	struct kstat stat;
721	__be32 err;
722
723	if (fhp->fh_no_wcc || fhp->fh_pre_saved)
724		return nfs_ok;
725
726	err = fh_getattr(fhp, &stat);
727	if (err)
728		return err;
729
730	if (v4)
731		fhp->fh_pre_change = nfsd4_change_attribute(&stat);
732
733	fhp->fh_pre_mtime = stat.mtime;
734	fhp->fh_pre_ctime = stat.ctime;
735	fhp->fh_pre_size  = stat.size;
736	fhp->fh_pre_saved = true;
737	return nfs_ok;
738}
739
740/**
741 * fh_fill_post_attrs - Fill in post-op attributes
742 * @fhp: file handle to be updated
743 *
744 */
745__be32 fh_fill_post_attrs(struct svc_fh *fhp)
746{
747	bool v4 = (fhp->fh_maxsize == NFS4_FHSIZE);
748	__be32 err;
749
750	if (fhp->fh_no_wcc)
751		return nfs_ok;
752
753	if (fhp->fh_post_saved)
754		printk("nfsd: inode locked twice during operation.\n");
755
756	err = fh_getattr(fhp, &fhp->fh_post_attr);
757	if (err)
758		return err;
759
760	fhp->fh_post_saved = true;
761	if (v4)
762		fhp->fh_post_change =
763			nfsd4_change_attribute(&fhp->fh_post_attr);
764	return nfs_ok;
765}
766
767/**
768 * fh_fill_both_attrs - Fill pre-op and post-op attributes
769 * @fhp: file handle to be updated
770 *
771 * This is used when the directory wasn't changed, but wcc attributes
772 * are needed anyway.
773 */
774__be32 __must_check fh_fill_both_attrs(struct svc_fh *fhp)
775{
776	__be32 err;
777
778	err = fh_fill_post_attrs(fhp);
779	if (err)
780		return err;
781
782	fhp->fh_pre_change = fhp->fh_post_change;
783	fhp->fh_pre_mtime = fhp->fh_post_attr.mtime;
784	fhp->fh_pre_ctime = fhp->fh_post_attr.ctime;
785	fhp->fh_pre_size = fhp->fh_post_attr.size;
786	fhp->fh_pre_saved = true;
787	return nfs_ok;
788}
789
790/*
791 * Release a file handle.
792 */
793void
794fh_put(struct svc_fh *fhp)
795{
796	struct dentry * dentry = fhp->fh_dentry;
797	struct svc_export * exp = fhp->fh_export;
798	if (dentry) {
799		fhp->fh_dentry = NULL;
800		dput(dentry);
801		fh_clear_pre_post_attrs(fhp);
802	}
803	fh_drop_write(fhp);
804	if (exp) {
805		exp_put(exp);
806		fhp->fh_export = NULL;
807	}
808	fhp->fh_no_wcc = false;
809	return;
810}
811
812/*
813 * Shorthand for dprintk()'s
814 */
815char * SVCFH_fmt(struct svc_fh *fhp)
816{
817	struct knfsd_fh *fh = &fhp->fh_handle;
818	static char buf[2+1+1+64*3+1];
819
820	if (fh->fh_size > 64)
821		return "bad-fh";
822	sprintf(buf, "%d: %*ph", fh->fh_size, fh->fh_size, fh->fh_raw);
823	return buf;
824}
825
826enum fsid_source fsid_source(const struct svc_fh *fhp)
827{
828	if (fhp->fh_handle.fh_version != 1)
829		return FSIDSOURCE_DEV;
830	switch(fhp->fh_handle.fh_fsid_type) {
831	case FSID_DEV:
832	case FSID_ENCODE_DEV:
833	case FSID_MAJOR_MINOR:
834		if (exp_sb(fhp->fh_export)->s_type->fs_flags & FS_REQUIRES_DEV)
835			return FSIDSOURCE_DEV;
836		break;
837	case FSID_NUM:
838		if (fhp->fh_export->ex_flags & NFSEXP_FSID)
839			return FSIDSOURCE_FSID;
840		break;
841	default:
842		break;
843	}
844	/* either a UUID type filehandle, or the filehandle doesn't
845	 * match the export.
846	 */
847	if (fhp->fh_export->ex_flags & NFSEXP_FSID)
848		return FSIDSOURCE_FSID;
849	if (fhp->fh_export->ex_uuid)
850		return FSIDSOURCE_UUID;
851	return FSIDSOURCE_DEV;
852}
853
854/**
855 * nfsd4_change_attribute - Generate an NFSv4 change_attribute value
856 * @stat: inode attributes
857 *
858 * Caller must fill in @stat before calling, typically by invoking
859 * vfs_getattr() with STATX_MODE, STATX_CTIME, and STATX_CHANGE_COOKIE.
860 * Returns an unsigned 64-bit changeid4 value (RFC 8881 Section 3.2).
861 *
862 * We could use i_version alone as the change attribute.  However, i_version
863 * can go backwards on a regular file after an unclean shutdown.  On its own
864 * that doesn't necessarily cause a problem, but if i_version goes backwards
865 * and then is incremented again it could reuse a value that was previously
866 * used before boot, and a client who queried the two values might incorrectly
867 * assume nothing changed.
868 *
869 * By using both ctime and the i_version counter we guarantee that as long as
870 * time doesn't go backwards we never reuse an old value. If the filesystem
871 * advertises STATX_ATTR_CHANGE_MONOTONIC, then this mitigation is not
872 * needed.
873 *
874 * We only need to do this for regular files as well. For directories, we
875 * assume that the new change attr is always logged to stable storage in some
876 * fashion before the results can be seen.
877 */
878u64 nfsd4_change_attribute(const struct kstat *stat)
879{
880	u64 chattr;
881
882	if (stat->result_mask & STATX_CHANGE_COOKIE) {
883		chattr = stat->change_cookie;
884		if (S_ISREG(stat->mode) &&
885		    !(stat->attributes & STATX_ATTR_CHANGE_MONOTONIC)) {
886			chattr += (u64)stat->ctime.tv_sec << 30;
887			chattr += stat->ctime.tv_nsec;
888		}
889	} else {
890		chattr = time_to_chattr(&stat->ctime);
891	}
892	return chattr;
893}