summaryrefslogtreecommitdiffstats
path: root/fs/ceph/auth_x.c
blob: 8d8a8496476328c500e7e959e6a9fcbb90ac5d1d (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
#include "ceph_debug.h"

#include <linux/err.h>
#include <linux/module.h>
#include <linux/random.h>

#include "auth_x.h"
#include "auth_x_protocol.h"
#include "crypto.h"
#include "auth.h"
#include "decode.h"

struct kmem_cache *ceph_x_ticketbuf_cachep;

#define TEMP_TICKET_BUF_LEN	256

static void ceph_x_validate_tickets(struct ceph_auth_client *ac, int *pneed);

static int ceph_x_is_authenticated(struct ceph_auth_client *ac)
{
	struct ceph_x_info *xi = ac->private;
	int need;

	ceph_x_validate_tickets(ac, &need);
	dout("ceph_x_is_authenticated want=%d need=%d have=%d\n",
	     ac->want_keys, need, xi->have_keys);
	return (ac->want_keys & xi->have_keys) == ac->want_keys;
}

static int ceph_x_encrypt_buflen(int ilen)
{
	return sizeof(struct ceph_x_encrypt_header) + ilen + 16 +
		sizeof(u32);
}

static int ceph_x_encrypt(struct ceph_crypto_key *secret,
			  void *ibuf, int ilen, void *obuf, size_t olen)
{
	struct ceph_x_encrypt_header head = {
		.struct_v = 1,
		.magic = cpu_to_le64(CEPHX_ENC_MAGIC)
	};
	size_t len = olen - sizeof(u32);
	int ret;

	ret = ceph_encrypt2(secret, obuf + sizeof(u32), &len,
			    &head, sizeof(head), ibuf, ilen);
	if (ret)
		return ret;
	ceph_encode_32(&obuf, len);
	return len + sizeof(u32);
}

static int ceph_x_decrypt(struct ceph_crypto_key *secret,
			  void **p, void *end, void *obuf, size_t olen)
{
	struct ceph_x_encrypt_header head;
	size_t head_len = sizeof(head);
	int len, ret;

	len = ceph_decode_32(p);
	if (*p + len > end)
		return -EINVAL;

	dout("ceph_x_decrypt len %d\n", len);
	ret = ceph_decrypt2(secret, &head, &head_len, obuf, &olen,
			    *p, len);
	if (ret)
		return ret;
	if (head.struct_v != 1 || le64_to_cpu(head.magic) != CEPHX_ENC_MAGIC)
		return -EPERM;
	*p += len;
	return olen;
}

/*
 * get existing (or insert new) ticket handler
 */
struct ceph_x_ticket_handler *get_ticket_handler(struct ceph_auth_client *ac,
						 int service)
{
	struct ceph_x_ticket_handler *th;
	struct ceph_x_info *xi = ac->private;
	struct rb_node *parent = NULL, **p = &xi->ticket_handlers.rb_node;

	while (*p) {
		parent = *p;
		th = rb_entry(parent, struct ceph_x_ticket_handler, node);
		if (service < th->service)
			p = &(*p)->rb_left;
		else if (service > th->service)
			p = &(*p)->rb_right;
		else
			return th;
	}

	/* add it */
	th = kzalloc(sizeof(*th), GFP_NOFS);
	if (!th)
		return ERR_PTR(-ENOMEM);
	th->service = service;
	rb_link_node(&th->node, parent, p);
	rb_insert_color(&th->node, &xi->ticket_handlers);
	return th;
}

static void remove_ticket_handler(struct ceph_auth_client *ac,
				  struct ceph_x_ticket_handler *th)
{
	struct ceph_x_info *xi = ac->private;

	dout("remove_ticket_handler %p %d\n", th, th->service);
	rb_erase(&th->node, &xi->ticket_handlers);
	ceph_crypto_key_destroy(&th->session_key);
	if (th->ticket_blob)
		ceph_buffer_put(th->ticket_blob);
	kfree(th);
}

static int ceph_x_proc_ticket_reply(struct ceph_auth_client *ac,
				    struct ceph_crypto_key *secret,
				    void *buf, void *end)
{
	struct ceph_x_info *xi = ac->private;
	int num;
	void *p = buf;
	int ret;
	char *dbuf;
	char *ticket_buf;
	u8 struct_v;

	dbuf = kmem_cache_alloc(ceph_x_ticketbuf_cachep, GFP_NOFS | GFP_ATOMIC);
	if (!dbuf)
		return -ENOMEM;

	ret = -ENOMEM;
	ticket_buf = kmem_cache_alloc(ceph_x_ticketbuf_cachep,
				      GFP_NOFS | GFP_ATOMIC);
	if (!ticket_buf)
		goto out_dbuf;

	ceph_decode_need(&p, end, 1 + sizeof(u32), bad);
	struct_v = ceph_decode_8(&p);
	if (struct_v != 1)
		goto bad;
	num = ceph_decode_32(&p);
	dout("%d tickets\n", num);
	while (num--) {
		int type;
		u8 struct_v;
		struct ceph_x_ticket_handler *th;
		void *dp, *dend;
		int dlen;
		char is_enc;
		struct timespec validity;
		struct ceph_crypto_key old_key;
		void *tp, *tpend;
		struct ceph_timespec new_validity;
		struct ceph_crypto_key new_session_key;
		struct ceph_buffer *new_ticket_blob;
		unsigned long new_expires, new_renew_after;
		u64 new_secret_id;

		ceph_decode_need(&p, end, sizeof(u32) + 1, bad);

		type = ceph_decode_32(&p);
		dout(" ticket type %d %s\n", type, ceph_entity_type_name(type));

		struct_v = ceph_decode_8(&p);
		if (struct_v != 1)
			goto bad;

		th = get_ticket_handler(ac, type);
		if (IS_ERR(th)) {
			ret = PTR_ERR(th);
			goto out;
		}

		/* blob for me */
		dlen = ceph_x_decrypt(secret, &p, end, dbuf,
				      TEMP_TICKET_BUF_LEN);
		if (dlen <= 0) {
			ret = dlen;
			goto out;
		}
		dout(" decrypted %d bytes\n", dlen);
		dend = dbuf + dlen;
		dp = dbuf;

		struct_v = ceph_decode_8(&dp);
		if (struct_v != 1)
			goto bad;

		memcpy(&old_key, &th->session_key, sizeof(old_key));
		ret = ceph_crypto_key_decode(&new_session_key, &dp, dend);
		if (ret)
			goto out;

		ceph_decode_copy(&dp, &new_validity, sizeof(new_validity));
		ceph_decode_timespec(&validity, &new_validity);
		new_expires = get_seconds() + validity.tv_sec;
		new_renew_after = new_expires - (validity.tv_sec / 4);
		dout(" expires=%lu renew_after=%lu\n", new_expires,
		     new_renew_after);

		/* ticket blob for service */
		ceph_decode_8_safe(&p, end, is_enc, bad);
		tp = ticket_buf;
		if (is_enc) {
			/* encrypted */
			dout(" encrypted ticket\n");
			dlen = ceph_x_decrypt(&old_key, &p, end, ticket_buf,
					      TEMP_TICKET_BUF_LEN);
			if (dlen < 0) {
				ret = dlen;
				goto out;
			}
			dlen = ceph_decode_32(&tp);
		} else {
			/* unencrypted */
			ceph_decode_32_safe(&p, end, dlen, bad);
			ceph_decode_need(&p, end, dlen, bad);
			ceph_decode_copy(&p, ticket_buf, dlen);
		}
		tpend = tp + dlen;
		dout(" ticket blob is %d bytes\n", dlen);
		ceph_decode_need(&tp, tpend, 1 + sizeof(u64), bad);
		struct_v = ceph_decode_8(&tp);
		new_secret_id = ceph_decode_64(&tp);
		ret = ceph_decode_buffer(&new_ticket_blob, &tp, tpend);
		if (ret)
			goto out;

		/* all is well, update our ticket */
		ceph_crypto_key_destroy(&th->session_key);
		if (th->ticket_blob)
			ceph_buffer_put(th->ticket_blob);
		th->session_key = new_session_key;
		th->ticket_blob = new_ticket_blob;
		th->validity = new_validity;
		th->secret_id = new_secret_id;
		th->expires = new_expires;
		th->renew_after = new_renew_after;
		dout(" got ticket service %d (%s) secret_id %lld len %d\n",
		     type, ceph_entity_type_name(type), th->secret_id,
		     (int)th->ticket_blob->vec.iov_len);
		xi->have_keys |= th->service;
	}

	ret = 0;
out:
	kmem_cache_free(ceph_x_ticketbuf_cachep, ticket_buf);
out_dbuf:
	kmem_cache_free(ceph_x_ticketbuf_cachep, dbuf);
	return ret;

bad:
	ret = -EINVAL;
	goto out;
}

static int ceph_x_build_authorizer(struct ceph_auth_client *ac,
				   struct ceph_x_ticket_handler *th,
				   struct ceph_x_authorizer *au)
{
	int maxlen;
	struct ceph_x_authorize_a *msg_a;
	struct ceph_x_authorize_b msg_b;
	void *p, *end;
	int ret;
	int ticket_blob_len =
		(th->ticket_blob ? th->ticket_blob->vec.iov_len : 0);

	dout("build_authorizer for %s %p\n",
	     ceph_entity_type_name(th->service), au);

	maxlen = sizeof(*msg_a) + sizeof(msg_b) +
		ceph_x_encrypt_buflen(ticket_blob_len);
	dout("  need len %d\n", maxlen);
	if (au->buf && au->buf->alloc_len < maxlen) {
		ceph_buffer_put(au->buf);
		au->buf = NULL;
	}
	if (!au->buf) {
		au->buf = ceph_buffer_new(maxlen, GFP_NOFS);
		if (!au->buf)
			return -ENOMEM;
	}
	au->service = th->service;

	msg_a = au->buf->vec.iov_base;
	msg_a->struct_v = 1;
	msg_a->global_id = cpu_to_le64(ac->global_id);
	msg_a->service_id = cpu_to_le32(th->service);
	msg_a->ticket_blob.struct_v = 1;
	msg_a->ticket_blob.secret_id = cpu_to_le64(th->secret_id);
	msg_a->ticket_blob.blob_len = cpu_to_le32(ticket_blob_len);
	if (ticket_blob_len) {
		memcpy(msg_a->ticket_blob.blob, th->ticket_blob->vec.iov_base,
		       th->ticket_blob->vec.iov_len);
	}
	dout(" th %p secret_id %lld %lld\n", th, th->secret_id,
	     le64_to_cpu(msg_a->ticket_blob.secret_id));

	p = msg_a + 1;
	p += ticket_blob_len;
	end = au->buf->vec.iov_base + au->buf->vec.iov_len;

	get_random_bytes(&au->nonce, sizeof(au->nonce));
	msg_b.struct_v = 1;
	msg_b.nonce = cpu_to_le64(au->nonce);
	ret = ceph_x_encrypt(&th->session_key, &msg_b, sizeof(msg_b),
			     p, end - p);
	if (ret < 0)
		goto out_buf;
	p += ret;
	au->buf->vec.iov_len = p - au->buf->vec.iov_base;
	dout(" built authorizer nonce %llx len %d\n", au->nonce,
	     (int)au->buf->vec.iov_len);
	BUG_ON(au->buf->vec.iov_len > maxlen);
	return 0;

out_buf:
	ceph_buffer_put(au->buf);
	au->buf = NULL;
	return ret;
}

static int ceph_x_encode_ticket(struct ceph_x_ticket_handler *th,
				void **p, void *end)
{
	ceph_decode_need(p, end, 1 + sizeof(u64), bad);
	ceph_encode_8(p, 1);
	ceph_encode_64(p, th->secret_id);
	if (th->ticket_blob) {
		const char *buf = th->ticket_blob->vec.iov_base;
		u32 len = th->ticket_blob->vec.iov_len;

		ceph_encode_32_safe(p, end, len, bad);
		ceph_encode_copy_safe(p, end, buf, len, bad);
	} else {
		ceph_encode_32_safe(p, end, 0, bad);
	}

	return 0;
bad:
	return -ERANGE;
}

static void ceph_x_validate_tickets(struct ceph_auth_client *ac, int *pneed)
{
	int want = ac->want_keys;
	struct ceph_x_info *xi = ac->private;
	int service;

	*pneed = ac->want_keys & ~(xi->have_keys);

	for (service = 1; service <= want; service <<= 1) {
		struct ceph_x_ticket_handler *th;

		if (!(ac->want_keys & service))
			continue;

		if (*pneed & service)
			continue;

		th = get_ticket_handler(ac, service);

		if (!th) {
			*pneed |= service;
			continue;
		}

		if (get_seconds() >= th->renew_after)
			*pneed |= service;
		if (get_seconds() >= th->expires)
			xi->have_keys &= ~service;
	}
}


static int ceph_x_build_request(struct ceph_auth_client *ac,
				void *buf, void *end)
{
	struct ceph_x_info *xi = ac->private;
	int need;
	struct ceph_x_request_header *head = buf;
	int ret;
	struct ceph_x_ticket_handler *th =
		get_ticket_handler(ac, CEPH_ENTITY_TYPE_AUTH);

	ceph_x_validate_tickets(ac, &need);

	dout("build_request want %x have %x need %x\n",
	     ac->want_keys, xi->have_keys, need);

	if (need & CEPH_ENTITY_TYPE_AUTH) {
		struct ceph_x_authenticate *auth = (void *)(head + 1);
		void *p = auth + 1;
		struct ceph_x_challenge_blob tmp;
		char tmp_enc[40];
		u64 *u;

		if (p > end)
			return -ERANGE;

		dout(" get_auth_session_key\n");
		head->op = cpu_to_le16(CEPHX_GET_AUTH_SESSION_KEY);

		/* encrypt and hash */
		get_random_bytes(&auth->client_challenge, sizeof(u64));
		tmp.client_challenge = auth->client_challenge;
		tmp.server_challenge = cpu_to_le64(xi->server_challenge);
		ret = ceph_x_encrypt(&xi->secret, &tmp, sizeof(tmp),
				     tmp_enc, sizeof(tmp_enc));
		if (ret < 0)
			return ret;

		auth->struct_v = 1;
		auth->key = 0;
		for (u = (u64 *)tmp_enc; u + 1 <= (u64 *)(tmp_enc + ret); u++)
			auth->key ^= *u;
		dout(" server_challenge %llx client_challenge %llx key %llx\n",
		     xi->server_challenge, le64_to_cpu(auth->client_challenge),
		     le64_to_cpu(auth->key));

		/* now encode the old ticket if exists */
		ret = ceph_x_encode_ticket(th, &p, end);
		if (ret < 0)
			return ret;

		return p - buf;
	}

	if (need) {
		void *p = head + 1;
		struct ceph_x_service_ticket_request *req;

		if (p > end)
			return -ERANGE;
		head->op = cpu_to_le16(CEPHX_GET_PRINCIPAL_SESSION_KEY);

		BUG_ON(!th);
		ret = ceph_x_build_authorizer(ac, th, &xi->auth_authorizer);
		if (ret)
			return ret;
		ceph_encode_copy(&p, xi->auth_authorizer.buf->vec.iov_base,
				 xi->auth_authorizer.buf->vec.iov_len);

		req = p;
		req->keys = cpu_to_le32(need);
		p += sizeof(*req);
		return p - buf;
	}

	return 0;
}

static int ceph_x_handle_reply(struct ceph_auth_client *ac, int result,
			       void *buf, void *end)
{
	struct ceph_x_info *xi = ac->private;
	struct ceph_x_reply_header *head = buf;
	struct ceph_x_ticket_handler *th;
	int len = end - buf;
	int op;
	int ret;

	if (result)
		return result;  /* XXX hmm? */

	if (xi->starting) {
		/* it's a hello */
		struct ceph_x_server_challenge *sc = buf;

		if (len != sizeof(*sc))
			return -EINVAL;
		xi->server_challenge = le64_to_cpu(sc->server_challenge);
		dout("handle_reply got server challenge %llx\n",
		     xi->server_challenge);
		xi->starting = false;
		xi->have_keys &= ~CEPH_ENTITY_TYPE_AUTH;
		return -EAGAIN;
	}

	op = le32_to_cpu(head->op);
	result = le32_to_cpu(head->result);
	dout("handle_reply op %d result %d\n", op, result);
	switch (op) {
	case CEPHX_GET_AUTH_SESSION_KEY:
		/* verify auth key */
		ret = ceph_x_proc_ticket_reply(ac, &xi->secret,
					       buf + sizeof(*head), end);
		break;

	case CEPHX_GET_PRINCIPAL_SESSION_KEY:
		th = get_ticket_handler(ac, CEPH_ENTITY_TYPE_AUTH);
		BUG_ON(!th);
		ret = ceph_x_proc_ticket_reply(ac, &th->session_key,
					       buf + sizeof(*head), end);
		break;

	default:
		return -EINVAL;
	}
	if (ret)
		return ret;
	if (ac->want_keys == xi->have_keys)
		return 0;
	return -EAGAIN;
}

static int ceph_x_create_authorizer(
	struct ceph_auth_client *ac, int peer_type,
	struct ceph_authorizer **a,
	void **buf, size_t *len,
	void **reply_buf, size_t *reply_len)
{
	struct ceph_x_authorizer *au;
	struct ceph_x_ticket_handler *th;
	int ret;

	th = get_ticket_handler(ac, peer_type);
	if (IS_ERR(th))
		return PTR_ERR(th);

	au = kzalloc(sizeof(*au), GFP_NOFS);
	if (!au)
		return -ENOMEM;

	ret = ceph_x_build_authorizer(ac, th, au);
	if (ret) {
		kfree(au);
		return ret;
	}

	*a = (struct ceph_authorizer *)au;
	*buf = au->buf->vec.iov_base;
	*len = au->buf->vec.iov_len;
	*reply_buf = au->reply_buf;
	*reply_len = sizeof(au->reply_buf);
	return 0;
}

static int ceph_x_verify_authorizer_reply(struct ceph_auth_client *ac,
					  struct ceph_authorizer *a, size_t len)
{
	struct ceph_x_authorizer *au = (void *)a;
	struct ceph_x_ticket_handler *th;
	int ret = 0;
	struct ceph_x_authorize_reply reply;
	void *p = au->reply_buf;
	void *end = p + sizeof(au->reply_buf);

	th = get_ticket_handler(ac, au->service);
	if (!th)
		return -EIO;  /* hrm! */
	ret = ceph_x_decrypt(&th->session_key, &p, end, &reply, sizeof(reply));
	if (ret < 0)
		return ret;
	if (ret != sizeof(reply))
		return -EPERM;

	if (au->nonce + 1 != le64_to_cpu(reply.nonce_plus_one))
		ret = -EPERM;
	else
		ret = 0;
	dout("verify_authorizer_reply nonce %llx got %llx ret %d\n",
	     au->nonce, le64_to_cpu(reply.nonce_plus_one), ret);
	return ret;
}

static void ceph_x_destroy_authorizer(struct ceph_auth_client *ac,
				      struct ceph_authorizer *a)
{
	struct ceph_x_authorizer *au = (void *)a;

	ceph_buffer_put(au->buf);
	kfree(au);
}


static void ceph_x_reset(struct ceph_auth_client *ac)
{
	struct ceph_x_info *xi = ac->private;

	dout("reset\n");
	xi->starting = true;
	xi->server_challenge = 0;
}

static void ceph_x_destroy(struct ceph_auth_client *ac)
{
	struct ceph_x_info *xi = ac->private;
	struct rb_node *p;

	dout("ceph_x_destroy %p\n", ac);
	ceph_crypto_key_destroy(&xi->secret);

	while ((p = rb_first(&xi->ticket_handlers)) != NULL) {
		struct ceph_x_ticket_handler *th =
			rb_entry(p, struct ceph_x_ticket_handler, node);
		remove_ticket_handler(ac, th);
	}

	kmem_cache_destroy(ceph_x_ticketbuf_cachep);

	kfree(ac->private);
	ac->private = NULL;
}

static void ceph_x_invalidate_authorizer(struct ceph_auth_client *ac,
				   int peer_type)
{
	struct ceph_x_ticket_handler *th;

	th = get_ticket_handler(ac, peer_type);
	if (th && !IS_ERR(th))
		remove_ticket_handler(ac, th);
}


static const struct ceph_auth_client_ops ceph_x_ops = {
	.is_authenticated = ceph_x_is_authenticated,
	.build_request = ceph_x_build_request,
	.handle_reply = ceph_x_handle_reply,
	.create_authorizer = ceph_x_create_authorizer,
	.verify_authorizer_reply = ceph_x_verify_authorizer_reply,
	.destroy_authorizer = ceph_x_destroy_authorizer,
	.invalidate_authorizer = ceph_x_invalidate_authorizer,
	.reset =  ceph_x_reset,
	.destroy = ceph_x_destroy,
};


int ceph_x_init(struct ceph_auth_client *ac)
{
	struct ceph_x_info *xi;
	int ret;

	dout("ceph_x_init %p\n", ac);
	xi = kzalloc(sizeof(*xi), GFP_NOFS);
	if (!xi)
		return -ENOMEM;

	ret = -ENOMEM;
	ceph_x_ticketbuf_cachep = kmem_cache_create("ceph_x_ticketbuf",
				      TEMP_TICKET_BUF_LEN, 8,
				      (SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD),
				      NULL);
	if (!ceph_x_ticketbuf_cachep)
		goto done_nomem;
	ret = -EINVAL;
	if (!ac->secret) {
		pr_err("no secret set (for auth_x protocol)\n");
		goto done_nomem;
	}

	ret = ceph_crypto_key_unarmor(&xi->secret, ac->secret);
	if (ret)
		goto done_nomem;

	xi->starting = true;
	xi->ticket_handlers = RB_ROOT;

	ac->protocol = CEPH_AUTH_CEPHX;
	ac->private = xi;
	ac->ops = &ceph_x_ops;
	return 0;

done_nomem:
	kfree(xi);
	if (ceph_x_ticketbuf_cachep)
		kmem_cache_destroy(ceph_x_ticketbuf_cachep);
	return ret;
}