aboutsummaryrefslogtreecommitdiff
path: root/fs/nfs/idmap.c
blob: b701358c39c351d0613d1db29ebcf382ca8cb0a6 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
/*
 * fs/nfs/idmap.c
 *
 *  UID and GID to name mapping for clients.
 *
 *  Copyright (c) 2002 The Regents of the University of Michigan.
 *  All rights reserved.
 *
 *  Marius Aamodt Eriksen <marius@umich.edu>
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *  3. Neither the name of the University nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
 *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 *  DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 *  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 *  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 *  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 *  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
#include <linux/types.h>
#include <linux/parser.h>
#include <linux/fs.h>
#include <linux/nfs_idmap.h>
#include <net/net_namespace.h>
#include <linux/sunrpc/rpc_pipe_fs.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_fs_sb.h>
#include <linux/key.h>
#include <linux/keyctl.h>
#include <linux/key-type.h>
#include <keys/user-type.h>
#include <linux/module.h>

#include "internal.h"
#include "netns.h"

#define NFS_UINT_MAXLEN 11

static const struct cred *id_resolver_cache;
static struct key_type key_type_id_resolver_legacy;

struct idmap {
	struct rpc_pipe		*idmap_pipe;
	struct key_construction	*idmap_key_cons;
	struct mutex		idmap_mutex;
};

/**
 * nfs_fattr_init_names - initialise the nfs_fattr owner_name/group_name fields
 * @fattr: fully initialised struct nfs_fattr
 * @owner_name: owner name string cache
 * @group_name: group name string cache
 */
void nfs_fattr_init_names(struct nfs_fattr *fattr,
		struct nfs4_string *owner_name,
		struct nfs4_string *group_name)
{
	fattr->owner_name = owner_name;
	fattr->group_name = group_name;
}

static void nfs_fattr_free_owner_name(struct nfs_fattr *fattr)
{
	fattr->valid &= ~NFS_ATTR_FATTR_OWNER_NAME;
	kfree(fattr->owner_name->data);
}

static void nfs_fattr_free_group_name(struct nfs_fattr *fattr)
{
	fattr->valid &= ~NFS_ATTR_FATTR_GROUP_NAME;
	kfree(fattr->group_name->data);
}

static bool nfs_fattr_map_owner_name(struct nfs_server *server, struct nfs_fattr *fattr)
{
	struct nfs4_string *owner = fattr->owner_name;
	__u32 uid;

	if (!(fattr->valid & NFS_ATTR_FATTR_OWNER_NAME))
		return false;
	if (nfs_map_name_to_uid(server, owner->data, owner->len, &uid) == 0) {
		fattr->uid = uid;
		fattr->valid |= NFS_ATTR_FATTR_OWNER;
	}
	return true;
}

static bool nfs_fattr_map_group_name(struct nfs_server *server, struct nfs_fattr *fattr)
{
	struct nfs4_string *group = fattr->group_name;
	__u32 gid;

	if (!(fattr->valid & NFS_ATTR_FATTR_GROUP_NAME))
		return false;
	if (nfs_map_group_to_gid(server, group->data, group->len, &gid) == 0) {
		fattr->gid = gid;
		fattr->valid |= NFS_ATTR_FATTR_GROUP;
	}
	return true;
}

/**
 * nfs_fattr_free_names - free up the NFSv4 owner and group strings
 * @fattr: a fully initialised nfs_fattr structure
 */
void nfs_fattr_free_names(struct nfs_fattr *fattr)
{
	if (fattr->valid & NFS_ATTR_FATTR_OWNER_NAME)
		nfs_fattr_free_owner_name(fattr);
	if (fattr->valid & NFS_ATTR_FATTR_GROUP_NAME)
		nfs_fattr_free_group_name(fattr);
}

/**
 * nfs_fattr_map_and_free_names - map owner/group strings into uid/gid and free
 * @server: pointer to the filesystem nfs_server structure
 * @fattr: a fully initialised nfs_fattr structure
 *
 * This helper maps the cached NFSv4 owner/group strings in fattr into
 * their numeric uid/gid equivalents, and then frees the cached strings.
 */
void nfs_fattr_map_and_free_names(struct nfs_server *server, struct nfs_fattr *fattr)
{
	if (nfs_fattr_map_owner_name(server, fattr))
		nfs_fattr_free_owner_name(fattr);
	if (nfs_fattr_map_group_name(server, fattr))
		nfs_fattr_free_group_name(fattr);
}

static int nfs_map_string_to_numeric(const char *name, size_t namelen, __u32 *res)
{
	unsigned long val;
	char buf[16];

	if (memchr(name, '@', namelen) != NULL || namelen >= sizeof(buf))
		return 0;
	memcpy(buf, name, namelen);
	buf[namelen] = '\0';
	if (strict_strtoul(buf, 0, &val) != 0)
		return 0;
	*res = val;
	return 1;
}

static int nfs_map_numeric_to_string(__u32 id, char *buf, size_t buflen)
{
	return snprintf(buf, buflen, "%u", id);
}

static struct key_type key_type_id_resolver = {
	.name		= "id_resolver",
	.instantiate	= user_instantiate,
	.match		= user_match,
	.revoke		= user_revoke,
	.destroy	= user_destroy,
	.describe	= user_describe,
	.read		= user_read,
};

static int nfs_idmap_init_keyring(void)
{
	struct cred *cred;
	struct key *keyring;
	int ret = 0;

	printk(KERN_NOTICE "NFS: Registering the %s key type\n",
		key_type_id_resolver.name);

	cred = prepare_kernel_cred(NULL);
	if (!cred)
		return -ENOMEM;

	keyring = key_alloc(&key_type_keyring, ".id_resolver", 0, 0, cred,
			     (KEY_POS_ALL & ~KEY_POS_SETATTR) |
			     KEY_USR_VIEW | KEY_USR_READ,
			     KEY_ALLOC_NOT_IN_QUOTA);
	if (IS_ERR(keyring)) {
		ret = PTR_ERR(keyring);
		goto failed_put_cred;
	}

	ret = key_instantiate_and_link(keyring, NULL, 0, NULL, NULL);
	if (ret < 0)
		goto failed_put_key;

	ret = register_key_type(&key_type_id_resolver);
	if (ret < 0)
		goto failed_put_key;

	ret = register_key_type(&key_type_id_resolver_legacy);
	if (ret < 0)
		goto failed_reg_legacy;

	set_bit(KEY_FLAG_ROOT_CAN_CLEAR, &keyring->flags);
	cred->thread_keyring = keyring;
	cred->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING;
	id_resolver_cache = cred;
	return 0;

failed_reg_legacy:
	unregister_key_type(&key_type_id_resolver);
failed_put_key:
	key_put(keyring);
failed_put_cred:
	put_cred(cred);
	return ret;
}

static void nfs_idmap_quit_keyring(void)
{
	key_revoke(id_resolver_cache->thread_keyring);
	unregister_key_type(&key_type_id_resolver);
	unregister_key_type(&key_type_id_resolver_legacy);
	put_cred(id_resolver_cache);
}

/*
 * Assemble the description to pass to request_key()
 * This function will allocate a new string and update dest to point
 * at it.  The caller is responsible for freeing dest.
 *
 * On error 0 is returned.  Otherwise, the length of dest is returned.
 */
static ssize_t nfs_idmap_get_desc(const char *name, size_t namelen,
				const char *type, size_t typelen, char **desc)
{
	char *cp;
	size_t desclen = typelen + namelen + 2;

	*desc = kmalloc(desclen, GFP_KERNEL);
	if (!*desc)
		return -ENOMEM;

	cp = *desc;
	memcpy(cp, type, typelen);
	cp += typelen;
	*cp++ = ':';

	memcpy(cp, name, namelen);
	cp += namelen;
	*cp = '\0';
	return desclen;
}

static ssize_t nfs_idmap_request_key(struct key_type *key_type,
				     const char *name, size_t namelen,
				     const char *type, void *data,
				     size_t data_size, struct idmap *idmap)
{
	const struct cred *saved_cred;
	struct key *rkey;
	char *desc;
	struct user_key_payload *payload;
	ssize_t ret;

	ret = nfs_idmap_get_desc(name, namelen, type, strlen(type), &desc);
	if (ret <= 0)
		goto out;

	saved_cred = override_creds(id_resolver_cache);
	if (idmap)
		rkey = request_key_with_auxdata(key_type, desc, "", 0, idmap);
	else
		rkey = request_key(&key_type_id_resolver, desc, "");
	revert_creds(saved_cred);

	kfree(desc);
	if (IS_ERR(rkey)) {
		ret = PTR_ERR(rkey);
		goto out;
	}

	rcu_read_lock();
	rkey->perm |= KEY_USR_VIEW;

	ret = key_validate(rkey);
	if (ret < 0)
		goto out_up;

	payload = rcu_dereference(rkey->payload.data);
	if (IS_ERR_OR_NULL(payload)) {
		ret = PTR_ERR(payload);
		goto out_up;
	}

	ret = payload->datalen;
	if (ret > 0 && ret <= data_size)
		memcpy(data, payload->data, ret);
	else
		ret = -EINVAL;

out_up:
	rcu_read_unlock();
	key_put(rkey);
out:
	return ret;
}

static ssize_t nfs_idmap_get_key(const char *name, size_t namelen,
				 const char *type, void *data,
				 size_t data_size, struct idmap *idmap)
{
	ssize_t ret = nfs_idmap_request_key(&key_type_id_resolver,
					    name, namelen, type, data,
					    data_size, NULL);
	if (ret < 0) {
		mutex_lock(&idmap->idmap_mutex);
		ret = nfs_idmap_request_key(&key_type_id_resolver_legacy,
					    name, namelen, type, data,
					    data_size, idmap);
		mutex_unlock(&idmap->idmap_mutex);
	}
	return ret;
}

/* ID -> Name */
static ssize_t nfs_idmap_lookup_name(__u32 id, const char *type, char *buf,
				     size_t buflen, struct idmap *idmap)
{
	char id_str[NFS_UINT_MAXLEN];
	int id_len;
	ssize_t ret;

	id_len = snprintf(id_str, sizeof(id_str), "%u", id);
	ret = nfs_idmap_get_key(id_str, id_len, type, buf, buflen, idmap);
	if (ret < 0)
		return -EINVAL;
	return ret;
}

/* Name -> ID */
static int nfs_idmap_lookup_id(const char *name, size_t namelen, const char *type,
			       __u32 *id, struct idmap *idmap)
{
	char id_str[NFS_UINT_MAXLEN];
	long id_long;
	ssize_t data_size;
	int ret = 0;

	data_size = nfs_idmap_get_key(name, namelen, type, id_str, NFS_UINT_MAXLEN, idmap);
	if (data_size <= 0) {
		ret = -EINVAL;
	} else {
		ret = strict_strtol(id_str, 10, &id_long);
		*id = (__u32)id_long;
	}
	return ret;
}

/* idmap classic begins here */

enum {
	Opt_find_uid, Opt_find_gid, Opt_find_user, Opt_find_group, Opt_find_err
};

static const match_table_t nfs_idmap_tokens = {
	{ Opt_find_uid, "uid:%s" },
	{ Opt_find_gid, "gid:%s" },
	{ Opt_find_user, "user:%s" },
	{ Opt_find_group, "group:%s" },
	{ Opt_find_err, NULL }
};

static int nfs_idmap_legacy_upcall(struct key_construction *, const char *, void *);
static ssize_t idmap_pipe_downcall(struct file *, const char __user *,
				   size_t);
static void idmap_pipe_destroy_msg(struct rpc_pipe_msg *);

static const struct rpc_pipe_ops idmap_upcall_ops = {
	.upcall		= rpc_pipe_generic_upcall,
	.downcall	= idmap_pipe_downcall,
	.destroy_msg	= idmap_pipe_destroy_msg,
};

static struct key_type key_type_id_resolver_legacy = {
	.name		= "id_legacy",
	.instantiate	= user_instantiate,
	.match		= user_match,
	.revoke		= user_revoke,
	.destroy	= user_destroy,
	.describe	= user_describe,
	.read		= user_read,
	.request_key	= nfs_idmap_legacy_upcall,
};

static void __nfs_idmap_unregister(struct rpc_pipe *pipe)
{
	if (pipe->dentry)
		rpc_unlink(pipe->dentry);
}

static int __nfs_idmap_register(struct dentry *dir,
				     struct idmap *idmap,
				     struct rpc_pipe *pipe)
{
	struct dentry *dentry;

	dentry = rpc_mkpipe_dentry(dir, "idmap", idmap, pipe);
	if (IS_ERR(dentry))
		return PTR_ERR(dentry);
	pipe->dentry = dentry;
	return 0;
}

static void nfs_idmap_unregister(struct nfs_client *clp,
				      struct rpc_pipe *pipe)
{
	struct net *net = clp->cl_net;
	struct super_block *pipefs_sb;

	pipefs_sb = rpc_get_sb_net(net);
	if (pipefs_sb) {
		__nfs_idmap_unregister(pipe);
		rpc_put_sb_net(net);
	}
}

static int nfs_idmap_register(struct nfs_client *clp,
				   struct idmap *idmap,
				   struct rpc_pipe *pipe)
{
	struct net *net = clp->cl_net;
	struct super_block *pipefs_sb;
	int err = 0;

	pipefs_sb = rpc_get_sb_net(net);
	if (pipefs_sb) {
		if (clp->cl_rpcclient->cl_dentry)
			err = __nfs_idmap_register(clp->cl_rpcclient->cl_dentry,
						   idmap, pipe);
		rpc_put_sb_net(net);
	}
	return err;
}

int
nfs_idmap_new(struct nfs_client *clp)
{
	struct idmap *idmap;
	struct rpc_pipe *pipe;
	int error;

	BUG_ON(clp->cl_idmap != NULL);

	idmap = kzalloc(sizeof(*idmap), GFP_KERNEL);
	if (idmap == NULL)
		return -ENOMEM;

	pipe = rpc_mkpipe_data(&idmap_upcall_ops, 0);
	if (IS_ERR(pipe)) {
		error = PTR_ERR(pipe);
		kfree(idmap);
		return error;
	}
	error = nfs_idmap_register(clp, idmap, pipe);
	if (error) {
		rpc_destroy_pipe_data(pipe);
		kfree(idmap);
		return error;
	}
	idmap->idmap_pipe = pipe;
	mutex_init(&idmap->idmap_mutex);

	clp->cl_idmap = idmap;
	return 0;
}

void
nfs_idmap_delete(struct nfs_client *clp)
{
	struct idmap *idmap = clp->cl_idmap;

	if (!idmap)
		return;
	nfs_idmap_unregister(clp, idmap->idmap_pipe);
	rpc_destroy_pipe_data(idmap->idmap_pipe);
	clp->cl_idmap = NULL;
	kfree(idmap);
}

static int __rpc_pipefs_event(struct nfs_client *clp, unsigned long event,
			      struct super_block *sb)
{
	int err = 0;

	switch (event) {
	case RPC_PIPEFS_MOUNT:
		BUG_ON(clp->cl_rpcclient->cl_dentry == NULL);
		err = __nfs_idmap_register(clp->cl_rpcclient->cl_dentry,
						clp->cl_idmap,
						clp->cl_idmap->idmap_pipe);
		break;
	case RPC_PIPEFS_UMOUNT:
		if (clp->cl_idmap->idmap_pipe) {
			struct dentry *parent;

			parent = clp->cl_idmap->idmap_pipe->dentry->d_parent;
			__nfs_idmap_unregister(clp->cl_idmap->idmap_pipe);
			/*
			 * Note: This is a dirty hack. SUNRPC hook has been
			 * called already but simple_rmdir() call for the
			 * directory returned with error because of idmap pipe
			 * inside. Thus now we have to remove this directory
			 * here.
			 */
			if (rpc_rmdir(parent))
				printk(KERN_ERR "NFS: %s: failed to remove "
					"clnt dir!\n", __func__);
		}
		break;
	default:
		printk(KERN_ERR "NFS: %s: unknown event: %ld\n", __func__,
			event);
		return -ENOTSUPP;
	}
	return err;
}

static struct nfs_client *nfs_get_client_for_event(struct net *net, int event)
{
	struct nfs_net *nn = net_generic(net, nfs_net_id);
	struct dentry *cl_dentry;
	struct nfs_client *clp;
	int err;

restart:
	spin_lock(&nn->nfs_client_lock);
	list_for_each_entry(clp, &nn->nfs_client_list, cl_share_link) {
		/* Wait for initialisation to finish */
		if (clp->cl_cons_state == NFS_CS_INITING) {
			atomic_inc(&clp->cl_count);
			spin_unlock(&nn->nfs_client_lock);
			err = nfs_wait_client_init_complete(clp);
			nfs_put_client(clp);
			if (err)
				return NULL;
			goto restart;
		}
		/* Skip nfs_clients that failed to initialise */
		if (clp->cl_cons_state < 0)
			continue;
		smp_rmb();
		if (clp->rpc_ops != &nfs_v4_clientops)
			continue;
		cl_dentry = clp->cl_idmap->idmap_pipe->dentry;
		if (((event == RPC_PIPEFS_MOUNT) && cl_dentry) ||
		    ((event == RPC_PIPEFS_UMOUNT) && !cl_dentry))
			continue;
		atomic_inc(&clp->cl_count);
		spin_unlock(&nn->nfs_client_lock);
		return clp;
	}
	spin_unlock(&nn->nfs_client_lock);
	return NULL;
}

static int rpc_pipefs_event(struct notifier_block *nb, unsigned long event,
			    void *ptr)
{
	struct super_block *sb = ptr;
	struct nfs_client *clp;
	int error = 0;

	if (!try_module_get(THIS_MODULE))
		return 0;

	while ((clp = nfs_get_client_for_event(sb->s_fs_info, event))) {
		error = __rpc_pipefs_event(clp, event, sb);
		nfs_put_client(clp);
		if (error)
			break;
	}
	module_put(THIS_MODULE);
	return error;
}

#define PIPEFS_NFS_PRIO		1

static struct notifier_block nfs_idmap_block = {
	.notifier_call	= rpc_pipefs_event,
	.priority	= SUNRPC_PIPEFS_NFS_PRIO,
};

int nfs_idmap_init(void)
{
	int ret;
	ret = nfs_idmap_init_keyring();
	if (ret != 0)
		goto out;
	ret = rpc_pipefs_notifier_register(&nfs_idmap_block);
	if (ret != 0)
		nfs_idmap_quit_keyring();
out:
	return ret;
}

void nfs_idmap_quit(void)
{
	rpc_pipefs_notifier_unregister(&nfs_idmap_block);
	nfs_idmap_quit_keyring();
}

static int nfs_idmap_prepare_message(char *desc, struct idmap_msg *im,
				     struct rpc_pipe_msg *msg)
{
	substring_t substr;
	int token, ret;

	memset(im,  0, sizeof(*im));
	memset(msg, 0, sizeof(*msg));

	im->im_type = IDMAP_TYPE_GROUP;
	token = match_token(desc, nfs_idmap_tokens, &substr);

	switch (token) {
	case Opt_find_uid:
		im->im_type = IDMAP_TYPE_USER;
	case Opt_find_gid:
		im->im_conv = IDMAP_CONV_NAMETOID;
		ret = match_strlcpy(im->im_name, &substr, IDMAP_NAMESZ);
		break;

	case Opt_find_user:
		im->im_type = IDMAP_TYPE_USER;
	case Opt_find_group:
		im->im_conv = IDMAP_CONV_IDTONAME;
		ret = match_int(&substr, &im->im_id);
		break;

	default:
		ret = -EINVAL;
		goto out;
	}

	msg->data = im;
	msg->len  = sizeof(struct idmap_msg);

out:
	return ret;
}

static int nfs_idmap_legacy_upcall(struct key_construction *cons,
				   const char *op,
				   void *aux)
{
	struct rpc_pipe_msg *msg;
	struct idmap_msg *im;
	struct idmap *idmap = (struct idmap *)aux;
	struct key *key = cons->key;
	int ret = -ENOMEM;

	/* msg and im are freed in idmap_pipe_destroy_msg */
	msg = kmalloc(sizeof(*msg), GFP_KERNEL);
	if (!msg)
		goto out0;

	im = kmalloc(sizeof(*im), GFP_KERNEL);
	if (!im)
		goto out1;

	ret = nfs_idmap_prepare_message(key->description, im, msg);
	if (ret < 0)
		goto out2;

	BUG_ON(idmap->idmap_key_cons != NULL);
	idmap->idmap_key_cons = cons;

	ret = rpc_queue_upcall(idmap->idmap_pipe, msg);
	if (ret < 0)
		goto out2;

	return ret;

out2:
	kfree(im);
out1:
	kfree(msg);
out0:
	complete_request_key(cons, ret);
	return ret;
}

static int nfs_idmap_instantiate(struct key *key, struct key *authkey, char *data)
{
	return key_instantiate_and_link(key, data, strlen(data) + 1,
					id_resolver_cache->thread_keyring,
					authkey);
}

static int nfs_idmap_read_message(struct idmap_msg *im, struct key *key, struct key *authkey)
{
	char id_str[NFS_UINT_MAXLEN];
	int ret = -EINVAL;

	switch (im->im_conv) {
	case IDMAP_CONV_NAMETOID:
		sprintf(id_str, "%d", im->im_id);
		ret = nfs_idmap_instantiate(key, authkey, id_str);
		break;
	case IDMAP_CONV_IDTONAME:
		ret = nfs_idmap_instantiate(key, authkey, im->im_name);
		break;
	}

	return ret;
}

static ssize_t
idmap_pipe_downcall(struct file *filp, const char __user *src, size_t mlen)
{
	struct rpc_inode *rpci = RPC_I(filp->f_path.dentry->d_inode);
	struct idmap *idmap = (struct idmap *)rpci->private;
	struct key_construction *cons;
	struct idmap_msg im;
	size_t namelen_in;
	int ret;

	/* If instantiation is successful, anyone waiting for key construction
	 * will have been woken up and someone else may now have used
	 * idmap_key_cons - so after this point we may no longer touch it.
	 */
	cons = ACCESS_ONCE(idmap->idmap_key_cons);
	idmap->idmap_key_cons = NULL;

	if (mlen != sizeof(im)) {
		ret = -ENOSPC;
		goto out;
	}

	if (copy_from_user(&im, src, mlen) != 0) {
		ret = -EFAULT;
		goto out;
	}

	if (!(im.im_status & IDMAP_STATUS_SUCCESS)) {
		ret = mlen;
		complete_request_key(cons, -ENOKEY);
		goto out_incomplete;
	}

	namelen_in = strnlen(im.im_name, IDMAP_NAMESZ);
	if (namelen_in == 0 || namelen_in == IDMAP_NAMESZ) {
		ret = -EINVAL;
		goto out;
	}

	ret = nfs_idmap_read_message(&im, cons->key, cons->authkey);
	if (ret >= 0) {
		key_set_timeout(cons->key, nfs_idmap_cache_timeout);
		ret = mlen;
	}

out:
	complete_request_key(cons, ret);
out_incomplete:
	return ret;
}

static void
idmap_pipe_destroy_msg(struct rpc_pipe_msg *msg)
{
	/* Free memory allocated in nfs_idmap_legacy_upcall() */
	kfree(msg->data);
	kfree(msg);
}

int nfs_map_name_to_uid(const struct nfs_server *server, const char *name, size_t namelen, __u32 *uid)
{
	struct idmap *idmap = server->nfs_client->cl_idmap;

	if (nfs_map_string_to_numeric(name, namelen, uid))
		return 0;
	return nfs_idmap_lookup_id(name, namelen, "uid", uid, idmap);
}

int nfs_map_group_to_gid(const struct nfs_server *server, const char *name, size_t namelen, __u32 *gid)
{
	struct idmap *idmap = server->nfs_client->cl_idmap;

	if (nfs_map_string_to_numeric(name, namelen, gid))
		return 0;
	return nfs_idmap_lookup_id(name, namelen, "gid", gid, idmap);
}

int nfs_map_uid_to_name(const struct nfs_server *server, __u32 uid, char *buf, size_t buflen)
{
	struct idmap *idmap = server->nfs_client->cl_idmap;
	int ret = -EINVAL;

	if (!(server->caps & NFS_CAP_UIDGID_NOMAP))
		ret = nfs_idmap_lookup_name(uid, "user", buf, buflen, idmap);
	if (ret < 0)
		ret = nfs_map_numeric_to_string(uid, buf, buflen);
	return ret;
}
int nfs_map_gid_to_group(const struct nfs_server *server, __u32 gid, char *buf, size_t buflen)
{
	struct idmap *idmap = server->nfs_client->cl_idmap;
	int ret = -EINVAL;

	if (!(server->caps & NFS_CAP_UIDGID_NOMAP))
		ret = nfs_idmap_lookup_name(gid, "group", buf, buflen, idmap);
	if (ret < 0)
		ret = nfs_map_numeric_to_string(gid, buf, buflen);
	return ret;
}