summaryrefslogtreecommitdiffstats
path: root/crypto/algif_aead.c
blob: f138af18b5000245330d6dc43cc036b005d1fc19 (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
/*
 * algif_aead: User-space interface for AEAD algorithms
 *
 * Copyright (C) 2014, Stephan Mueller <smueller@chronox.de>
 *
 * This file provides the user-space API for AEAD ciphers.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 * The following concept of the memory management is used:
 *
 * The kernel maintains two SGLs, the TX SGL and the RX SGL. The TX SGL is
 * filled by user space with the data submitted via sendpage/sendmsg. Filling
 * up the TX SGL does not cause a crypto operation -- the data will only be
 * tracked by the kernel. Upon receipt of one recvmsg call, the caller must
 * provide a buffer which is tracked with the RX SGL.
 *
 * During the processing of the recvmsg operation, the cipher request is
 * allocated and prepared. As part of the recvmsg operation, the processed
 * TX buffers are extracted from the TX SGL into a separate SGL.
 *
 * After the completion of the crypto operation, the RX SGL and the cipher
 * request is released. The extracted TX SGL parts are released together with
 * the RX SGL release.
 */

#include <crypto/internal/aead.h>
#include <crypto/scatterwalk.h>
#include <crypto/if_alg.h>
#include <crypto/skcipher.h>
#include <crypto/null.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/net.h>
#include <net/sock.h>

struct aead_tfm {
	struct crypto_aead *aead;
	bool has_key;
	struct crypto_skcipher *null_tfm;
};

static inline bool aead_sufficient_data(struct sock *sk)
{
	struct alg_sock *ask = alg_sk(sk);
	struct sock *psk = ask->parent;
	struct alg_sock *pask = alg_sk(psk);
	struct af_alg_ctx *ctx = ask->private;
	struct aead_tfm *aeadc = pask->private;
	struct crypto_aead *tfm = aeadc->aead;
	unsigned int as = crypto_aead_authsize(tfm);

	/*
	 * The minimum amount of memory needed for an AEAD cipher is
	 * the AAD and in case of decryption the tag.
	 */
	return ctx->used >= ctx->aead_assoclen + (ctx->enc ? 0 : as);
}

static int aead_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
{
	struct sock *sk = sock->sk;
	struct alg_sock *ask = alg_sk(sk);
	struct sock *psk = ask->parent;
	struct alg_sock *pask = alg_sk(psk);
	struct aead_tfm *aeadc = pask->private;
	struct crypto_aead *tfm = aeadc->aead;
	unsigned int ivsize = crypto_aead_ivsize(tfm);

	return af_alg_sendmsg(sock, msg, size, ivsize);
}

static int crypto_aead_copy_sgl(struct crypto_skcipher *null_tfm,
				struct scatterlist *src,
				struct scatterlist *dst, unsigned int len)
{
	SKCIPHER_REQUEST_ON_STACK(skreq, null_tfm);

	skcipher_request_set_tfm(skreq, null_tfm);
	skcipher_request_set_callback(skreq, CRYPTO_TFM_REQ_MAY_BACKLOG,
				      NULL, NULL);
	skcipher_request_set_crypt(skreq, src, dst, len, NULL);

	return crypto_skcipher_encrypt(skreq);
}

static int _aead_recvmsg(struct socket *sock, struct msghdr *msg,
			 size_t ignored, int flags)
{
	struct sock *sk = sock->sk;
	struct alg_sock *ask = alg_sk(sk);
	struct sock *psk = ask->parent;
	struct alg_sock *pask = alg_sk(psk);
	struct af_alg_ctx *ctx = ask->private;
	struct aead_tfm *aeadc = pask->private;
	struct crypto_aead *tfm = aeadc->aead;
	struct crypto_skcipher *null_tfm = aeadc->null_tfm;
	unsigned int i, as = crypto_aead_authsize(tfm);
	struct af_alg_async_req *areq;
	struct af_alg_tsgl *tsgl, *tmp;
	struct scatterlist *rsgl_src, *tsgl_src = NULL;
	int err = 0;
	size_t used = 0;		/* [in]  TX bufs to be en/decrypted */
	size_t outlen = 0;		/* [out] RX bufs produced by kernel */
	size_t usedpages = 0;		/* [in]  RX bufs to be used from user */
	size_t processed = 0;		/* [in]  TX bufs to be consumed */

	if (!ctx->used) {
		err = af_alg_wait_for_data(sk, flags);
		if (err)
			return err;
	}

	/*
	 * Data length provided by caller via sendmsg/sendpage that has not
	 * yet been processed.
	 */
	used = ctx->used;

	/*
	 * Make sure sufficient data is present -- note, the same check is
	 * is also present in sendmsg/sendpage. The checks in sendpage/sendmsg
	 * shall provide an information to the data sender that something is
	 * wrong, but they are irrelevant to maintain the kernel integrity.
	 * We need this check here too in case user space decides to not honor
	 * the error message in sendmsg/sendpage and still call recvmsg. This
	 * check here protects the kernel integrity.
	 */
	if (!aead_sufficient_data(sk))
		return -EINVAL;

	/*
	 * Calculate the minimum output buffer size holding the result of the
	 * cipher operation. When encrypting data, the receiving buffer is
	 * larger by the tag length compared to the input buffer as the
	 * encryption operation generates the tag. For decryption, the input
	 * buffer provides the tag which is consumed resulting in only the
	 * plaintext without a buffer for the tag returned to the caller.
	 */
	if (ctx->enc)
		outlen = used + as;
	else
		outlen = used - as;

	/*
	 * The cipher operation input data is reduced by the associated data
	 * length as this data is processed separately later on.
	 */
	used -= ctx->aead_assoclen;

	/* Allocate cipher request for current operation. */
	areq = af_alg_alloc_areq(sk, sizeof(struct af_alg_async_req) +
				     crypto_aead_reqsize(tfm));
	if (IS_ERR(areq))
		return PTR_ERR(areq);

	/* convert iovecs of output buffers into RX SGL */
	err = af_alg_get_rsgl(sk, msg, flags, areq, outlen, &usedpages);
	if (err)
		goto free;

	/*
	 * Ensure output buffer is sufficiently large. If the caller provides
	 * less buffer space, only use the relative required input size. This
	 * allows AIO operation where the caller sent all data to be processed
	 * and the AIO operation performs the operation on the different chunks
	 * of the input data.
	 */
	if (usedpages < outlen) {
		size_t less = outlen - usedpages;

		if (used < less) {
			err = -EINVAL;
			goto free;
		}
		used -= less;
		outlen -= less;
	}

	processed = used + ctx->aead_assoclen;
	list_for_each_entry_safe(tsgl, tmp, &ctx->tsgl_list, list) {
		for (i = 0; i < tsgl->cur; i++) {
			struct scatterlist *process_sg = tsgl->sg + i;

			if (!(process_sg->length) || !sg_page(process_sg))
				continue;
			tsgl_src = process_sg;
			break;
		}
		if (tsgl_src)
			break;
	}
	if (processed && !tsgl_src) {
		err = -EFAULT;
		goto free;
	}

	/*
	 * Copy of AAD from source to destination
	 *
	 * The AAD is copied to the destination buffer without change. Even
	 * when user space uses an in-place cipher operation, the kernel
	 * will copy the data as it does not see whether such in-place operation
	 * is initiated.
	 *
	 * To ensure efficiency, the following implementation ensure that the
	 * ciphers are invoked to perform a crypto operation in-place. This
	 * is achieved by memory management specified as follows.
	 */

	/* Use the RX SGL as source (and destination) for crypto op. */
	rsgl_src = areq->first_rsgl.sgl.sg;

	if (ctx->enc) {
		/*
		 * Encryption operation - The in-place cipher operation is
		 * achieved by the following operation:
		 *
		 * TX SGL: AAD || PT
		 *	    |	   |
		 *	    | copy |
		 *	    v	   v
		 * RX SGL: AAD || PT || Tag
		 */
		err = crypto_aead_copy_sgl(null_tfm, tsgl_src,
					   areq->first_rsgl.sgl.sg, processed);
		if (err)
			goto free;
		af_alg_pull_tsgl(sk, processed, NULL, 0);
	} else {
		/*
		 * Decryption operation - To achieve an in-place cipher
		 * operation, the following  SGL structure is used:
		 *
		 * TX SGL: AAD || CT || Tag
		 *	    |	   |	 ^
		 *	    | copy |	 | Create SGL link.
		 *	    v	   v	 |
		 * RX SGL: AAD || CT ----+
		 */

		 /* Copy AAD || CT to RX SGL buffer for in-place operation. */
		err = crypto_aead_copy_sgl(null_tfm, tsgl_src,
					   areq->first_rsgl.sgl.sg, outlen);
		if (err)
			goto free;

		/* Create TX SGL for tag and chain it to RX SGL. */
		areq->tsgl_entries = af_alg_count_tsgl(sk, processed,
						       processed - as);
		if (!areq->tsgl_entries)
			areq->tsgl_entries = 1;
		areq->tsgl = sock_kmalloc(sk, sizeof(*areq->tsgl) *
					      areq->tsgl_entries,
					  GFP_KERNEL);
		if (!areq->tsgl) {
			err = -ENOMEM;
			goto free;
		}
		sg_init_table(areq->tsgl, areq->tsgl_entries);

		/* Release TX SGL, except for tag data and reassign tag data. */
		af_alg_pull_tsgl(sk, processed, areq->tsgl, processed - as);

		/* chain the areq TX SGL holding the tag with RX SGL */
		if (usedpages) {
			/* RX SGL present */
			struct af_alg_sgl *sgl_prev = &areq->last_rsgl->sgl;

			sg_unmark_end(sgl_prev->sg + sgl_prev->npages - 1);
			sg_chain(sgl_prev->sg, sgl_prev->npages + 1,
				 areq->tsgl);
		} else
			/* no RX SGL present (e.g. authentication only) */
			rsgl_src = areq->tsgl;
	}

	/* Initialize the crypto operation */
	aead_request_set_crypt(&areq->cra_u.aead_req, rsgl_src,
			       areq->first_rsgl.sgl.sg, used, ctx->iv);
	aead_request_set_ad(&areq->cra_u.aead_req, ctx->aead_assoclen);
	aead_request_set_tfm(&areq->cra_u.aead_req, tfm);

	if (msg->msg_iocb && !is_sync_kiocb(msg->msg_iocb)) {
		/* AIO operation */
		sock_hold(sk);
		areq->iocb = msg->msg_iocb;

		/* Remember output size that will be generated. */
		areq->outlen = outlen;

		aead_request_set_callback(&areq->cra_u.aead_req,
					  CRYPTO_TFM_REQ_MAY_BACKLOG,
					  af_alg_async_cb, areq);
		err = ctx->enc ? crypto_aead_encrypt(&areq->cra_u.aead_req) :
				 crypto_aead_decrypt(&areq->cra_u.aead_req);

		/* AIO operation in progress */
		if (err == -EINPROGRESS || err == -EBUSY)
			return -EIOCBQUEUED;

		sock_put(sk);
	} else {
		/* Synchronous operation */
		aead_request_set_callback(&areq->cra_u.aead_req,
					  CRYPTO_TFM_REQ_MAY_BACKLOG,
					  af_alg_complete, &ctx->completion);
		err = af_alg_wait_for_completion(ctx->enc ?
				crypto_aead_encrypt(&areq->cra_u.aead_req) :
				crypto_aead_decrypt(&areq->cra_u.aead_req),
						 &ctx->completion);
	}


free:
	af_alg_free_resources(areq);

	return err ? err : outlen;
}

static int aead_recvmsg(struct socket *sock, struct msghdr *msg,
			size_t ignored, int flags)
{
	struct sock *sk = sock->sk;
	int ret = 0;

	lock_sock(sk);
	while (msg_data_left(msg)) {
		int err = _aead_recvmsg(sock, msg, ignored, flags);

		/*
		 * This error covers -EIOCBQUEUED which implies that we can
		 * only handle one AIO request. If the caller wants to have
		 * multiple AIO requests in parallel, he must make multiple
		 * separate AIO calls.
		 *
		 * Also return the error if no data has been processed so far.
		 */
		if (err <= 0) {
			if (err == -EIOCBQUEUED || err == -EBADMSG || !ret)
				ret = err;
			goto out;
		}

		ret += err;
	}

out:
	af_alg_wmem_wakeup(sk);
	release_sock(sk);
	return ret;
}

static struct proto_ops algif_aead_ops = {
	.family		=	PF_ALG,

	.connect	=	sock_no_connect,
	.socketpair	=	sock_no_socketpair,
	.getname	=	sock_no_getname,
	.ioctl		=	sock_no_ioctl,
	.listen		=	sock_no_listen,
	.shutdown	=	sock_no_shutdown,
	.getsockopt	=	sock_no_getsockopt,
	.mmap		=	sock_no_mmap,
	.bind		=	sock_no_bind,
	.accept		=	sock_no_accept,
	.setsockopt	=	sock_no_setsockopt,

	.release	=	af_alg_release,
	.sendmsg	=	aead_sendmsg,
	.sendpage	=	af_alg_sendpage,
	.recvmsg	=	aead_recvmsg,
	.poll		=	af_alg_poll,
};

static int aead_check_key(struct socket *sock)
{
	int err = 0;
	struct sock *psk;
	struct alg_sock *pask;
	struct aead_tfm *tfm;
	struct sock *sk = sock->sk;
	struct alg_sock *ask = alg_sk(sk);

	lock_sock(sk);
	if (ask->refcnt)
		goto unlock_child;

	psk = ask->parent;
	pask = alg_sk(ask->parent);
	tfm = pask->private;

	err = -ENOKEY;
	lock_sock_nested(psk, SINGLE_DEPTH_NESTING);
	if (!tfm->has_key)
		goto unlock;

	if (!pask->refcnt++)
		sock_hold(psk);

	ask->refcnt = 1;
	sock_put(psk);

	err = 0;

unlock:
	release_sock(psk);
unlock_child:
	release_sock(sk);

	return err;
}

static int aead_sendmsg_nokey(struct socket *sock, struct msghdr *msg,
				  size_t size)
{
	int err;

	err = aead_check_key(sock);
	if (err)
		return err;

	return aead_sendmsg(sock, msg, size);
}

static ssize_t aead_sendpage_nokey(struct socket *sock, struct page *page,
				       int offset, size_t size, int flags)
{
	int err;

	err = aead_check_key(sock);
	if (err)
		return err;

	return af_alg_sendpage(sock, page, offset, size, flags);
}

static int aead_recvmsg_nokey(struct socket *sock, struct msghdr *msg,
				  size_t ignored, int flags)
{
	int err;

	err = aead_check_key(sock);
	if (err)
		return err;

	return aead_recvmsg(sock, msg, ignored, flags);
}

static struct proto_ops algif_aead_ops_nokey = {
	.family		=	PF_ALG,

	.connect	=	sock_no_connect,
	.socketpair	=	sock_no_socketpair,
	.getname	=	sock_no_getname,
	.ioctl		=	sock_no_ioctl,
	.listen		=	sock_no_listen,
	.shutdown	=	sock_no_shutdown,
	.getsockopt	=	sock_no_getsockopt,
	.mmap		=	sock_no_mmap,
	.bind		=	sock_no_bind,
	.accept		=	sock_no_accept,
	.setsockopt	=	sock_no_setsockopt,

	.release	=	af_alg_release,
	.sendmsg	=	aead_sendmsg_nokey,
	.sendpage	=	aead_sendpage_nokey,
	.recvmsg	=	aead_recvmsg_nokey,
	.poll		=	af_alg_poll,
};

static void *aead_bind(const char *name, u32 type, u32 mask)
{
	struct aead_tfm *tfm;
	struct crypto_aead *aead;
	struct crypto_skcipher *null_tfm;

	tfm = kzalloc(sizeof(*tfm), GFP_KERNEL);
	if (!tfm)
		return ERR_PTR(-ENOMEM);

	aead = crypto_alloc_aead(name, type, mask);
	if (IS_ERR(aead)) {
		kfree(tfm);
		return ERR_CAST(aead);
	}

	null_tfm = crypto_get_default_null_skcipher2();
	if (IS_ERR(null_tfm)) {
		crypto_free_aead(aead);
		kfree(tfm);
		return ERR_CAST(null_tfm);
	}

	tfm->aead = aead;
	tfm->null_tfm = null_tfm;

	return tfm;
}

static void aead_release(void *private)
{
	struct aead_tfm *tfm = private;

	crypto_free_aead(tfm->aead);
	crypto_put_default_null_skcipher2();
	kfree(tfm);
}

static int aead_setauthsize(void *private, unsigned int authsize)
{
	struct aead_tfm *tfm = private;

	return crypto_aead_setauthsize(tfm->aead, authsize);
}

static int aead_setkey(void *private, const u8 *key, unsigned int keylen)
{
	struct aead_tfm *tfm = private;
	int err;

	err = crypto_aead_setkey(tfm->aead, key, keylen);
	tfm->has_key = !err;

	return err;
}

static void aead_sock_destruct(struct sock *sk)
{
	struct alg_sock *ask = alg_sk(sk);
	struct af_alg_ctx *ctx = ask->private;
	struct sock *psk = ask->parent;
	struct alg_sock *pask = alg_sk(psk);
	struct aead_tfm *aeadc = pask->private;
	struct crypto_aead *tfm = aeadc->aead;
	unsigned int ivlen = crypto_aead_ivsize(tfm);

	af_alg_pull_tsgl(sk, ctx->used, NULL, 0);
	sock_kzfree_s(sk, ctx->iv, ivlen);
	sock_kfree_s(sk, ctx, ctx->len);
	af_alg_release_parent(sk);
}

static int aead_accept_parent_nokey(void *private, struct sock *sk)
{
	struct af_alg_ctx *ctx;
	struct alg_sock *ask = alg_sk(sk);
	struct aead_tfm *tfm = private;
	struct crypto_aead *aead = tfm->aead;
	unsigned int len = sizeof(*ctx);
	unsigned int ivlen = crypto_aead_ivsize(aead);

	ctx = sock_kmalloc(sk, len, GFP_KERNEL);
	if (!ctx)
		return -ENOMEM;
	memset(ctx, 0, len);

	ctx->iv = sock_kmalloc(sk, ivlen, GFP_KERNEL);
	if (!ctx->iv) {
		sock_kfree_s(sk, ctx, len);
		return -ENOMEM;
	}
	memset(ctx->iv, 0, ivlen);

	INIT_LIST_HEAD(&ctx->tsgl_list);
	ctx->len = len;
	ctx->used = 0;
	atomic_set(&ctx->rcvused, 0);
	ctx->more = 0;
	ctx->merge = 0;
	ctx->enc = 0;
	ctx->aead_assoclen = 0;
	af_alg_init_completion(&ctx->completion);

	ask->private = ctx;

	sk->sk_destruct = aead_sock_destruct;

	return 0;
}

static int aead_accept_parent(void *private, struct sock *sk)
{
	struct aead_tfm *tfm = private;

	if (!tfm->has_key)
		return -ENOKEY;

	return aead_accept_parent_nokey(private, sk);
}

static const struct af_alg_type algif_type_aead = {
	.bind		=	aead_bind,
	.release	=	aead_release,
	.setkey		=	aead_setkey,
	.setauthsize	=	aead_setauthsize,
	.accept		=	aead_accept_parent,
	.accept_nokey	=	aead_accept_parent_nokey,
	.ops		=	&algif_aead_ops,
	.ops_nokey	=	&algif_aead_ops_nokey,
	.name		=	"aead",
	.owner		=	THIS_MODULE
};

static int __init algif_aead_init(void)
{
	return af_alg_register_type(&algif_type_aead);
}

static void __exit algif_aead_exit(void)
{
	int err = af_alg_unregister_type(&algif_type_aead);
	BUG_ON(err);
}

module_init(algif_aead_init);
module_exit(algif_aead_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
MODULE_DESCRIPTION("AEAD kernel crypto API user space interface");