aboutsummaryrefslogtreecommitdiff
path: root/net/tls/tls_device_fallback.c
blob: 28895333701e40f68b02cb62b4ad9aa845a05537 (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
/* Copyright (c) 2018, Mellanox Technologies All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - 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.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include <net/tls.h>
#include <crypto/aead.h>
#include <crypto/scatterwalk.h>
#include <net/ip6_checksum.h>

static void chain_to_walk(struct scatterlist *sg, struct scatter_walk *walk)
{
	struct scatterlist *src = walk->sg;
	int diff = walk->offset - src->offset;

	sg_set_page(sg, sg_page(src),
		    src->length - diff, walk->offset);

	scatterwalk_crypto_chain(sg, sg_next(src), 2);
}

static int tls_enc_record(struct aead_request *aead_req,
			  struct crypto_aead *aead, char *aad,
			  char *iv, __be64 rcd_sn,
			  struct scatter_walk *in,
			  struct scatter_walk *out, int *in_len)
{
	unsigned char buf[TLS_HEADER_SIZE + TLS_CIPHER_AES_GCM_128_IV_SIZE];
	struct scatterlist sg_in[3];
	struct scatterlist sg_out[3];
	u16 len;
	int rc;

	len = min_t(int, *in_len, ARRAY_SIZE(buf));

	scatterwalk_copychunks(buf, in, len, 0);
	scatterwalk_copychunks(buf, out, len, 1);

	*in_len -= len;
	if (!*in_len)
		return 0;

	scatterwalk_pagedone(in, 0, 1);
	scatterwalk_pagedone(out, 1, 1);

	len = buf[4] | (buf[3] << 8);
	len -= TLS_CIPHER_AES_GCM_128_IV_SIZE;

	tls_make_aad(aad, len - TLS_CIPHER_AES_GCM_128_TAG_SIZE,
		(char *)&rcd_sn, sizeof(rcd_sn), buf[0],
		TLS_1_2_VERSION);

	memcpy(iv + TLS_CIPHER_AES_GCM_128_SALT_SIZE, buf + TLS_HEADER_SIZE,
	       TLS_CIPHER_AES_GCM_128_IV_SIZE);

	sg_init_table(sg_in, ARRAY_SIZE(sg_in));
	sg_init_table(sg_out, ARRAY_SIZE(sg_out));
	sg_set_buf(sg_in, aad, TLS_AAD_SPACE_SIZE);
	sg_set_buf(sg_out, aad, TLS_AAD_SPACE_SIZE);
	chain_to_walk(sg_in + 1, in);
	chain_to_walk(sg_out + 1, out);

	*in_len -= len;
	if (*in_len < 0) {
		*in_len += TLS_CIPHER_AES_GCM_128_TAG_SIZE;
		/* the input buffer doesn't contain the entire record.
		 * trim len accordingly. The resulting authentication tag
		 * will contain garbage, but we don't care, so we won't
		 * include any of it in the output skb
		 * Note that we assume the output buffer length
		 * is larger then input buffer length + tag size
		 */
		if (*in_len < 0)
			len += *in_len;

		*in_len = 0;
	}

	if (*in_len) {
		scatterwalk_copychunks(NULL, in, len, 2);
		scatterwalk_pagedone(in, 0, 1);
		scatterwalk_copychunks(NULL, out, len, 2);
		scatterwalk_pagedone(out, 1, 1);
	}

	len -= TLS_CIPHER_AES_GCM_128_TAG_SIZE;
	aead_request_set_crypt(aead_req, sg_in, sg_out, len, iv);

	rc = crypto_aead_encrypt(aead_req);

	return rc;
}

static void tls_init_aead_request(struct aead_request *aead_req,
				  struct crypto_aead *aead)
{
	aead_request_set_tfm(aead_req, aead);
	aead_request_set_ad(aead_req, TLS_AAD_SPACE_SIZE);
}

static struct aead_request *tls_alloc_aead_request(struct crypto_aead *aead,
						   gfp_t flags)
{
	unsigned int req_size = sizeof(struct aead_request) +
		crypto_aead_reqsize(aead);
	struct aead_request *aead_req;

	aead_req = kzalloc(req_size, flags);
	if (aead_req)
		tls_init_aead_request(aead_req, aead);
	return aead_req;
}

static int tls_enc_records(struct aead_request *aead_req,
			   struct crypto_aead *aead, struct scatterlist *sg_in,
			   struct scatterlist *sg_out, char *aad, char *iv,
			   u64 rcd_sn, int len)
{
	struct scatter_walk out, in;
	int rc;

	scatterwalk_start(&in, sg_in);
	scatterwalk_start(&out, sg_out);

	do {
		rc = tls_enc_record(aead_req, aead, aad, iv,
				    cpu_to_be64(rcd_sn), &in, &out, &len);
		rcd_sn++;

	} while (rc == 0 && len);

	scatterwalk_done(&in, 0, 0);
	scatterwalk_done(&out, 1, 0);

	return rc;
}

/* Can't use icsk->icsk_af_ops->send_check here because the ip addresses
 * might have been changed by NAT.
 */
static void update_chksum(struct sk_buff *skb, int headln)
{
	struct tcphdr *th = tcp_hdr(skb);
	int datalen = skb->len - headln;
	const struct ipv6hdr *ipv6h;
	const struct iphdr *iph;

	/* We only changed the payload so if we are using partial we don't
	 * need to update anything.
	 */
	if (likely(skb->ip_summed == CHECKSUM_PARTIAL))
		return;

	skb->ip_summed = CHECKSUM_PARTIAL;
	skb->csum_start = skb_transport_header(skb) - skb->head;
	skb->csum_offset = offsetof(struct tcphdr, check);

	if (skb->sk->sk_family == AF_INET6) {
		ipv6h = ipv6_hdr(skb);
		th->check = ~csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr,
					     datalen, IPPROTO_TCP, 0);
	} else {
		iph = ip_hdr(skb);
		th->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr, datalen,
					       IPPROTO_TCP, 0);
	}
}

static void complete_skb(struct sk_buff *nskb, struct sk_buff *skb, int headln)
{
	struct sock *sk = skb->sk;
	int delta;

	skb_copy_header(nskb, skb);

	skb_put(nskb, skb->len);
	memcpy(nskb->data, skb->data, headln);

	nskb->destructor = skb->destructor;
	nskb->sk = sk;
	skb->destructor = NULL;
	skb->sk = NULL;

	update_chksum(nskb, headln);

	/* sock_efree means skb must gone through skb_orphan_partial() */
	if (nskb->destructor == sock_efree)
		return;

	delta = nskb->truesize - skb->truesize;
	if (likely(delta < 0))
		WARN_ON_ONCE(refcount_sub_and_test(-delta, &sk->sk_wmem_alloc));
	else if (delta)
		refcount_add(delta, &sk->sk_wmem_alloc);
}

/* This function may be called after the user socket is already
 * closed so make sure we don't use anything freed during
 * tls_sk_proto_close here
 */

static int fill_sg_in(struct scatterlist *sg_in,
		      struct sk_buff *skb,
		      struct tls_offload_context_tx *ctx,
		      u64 *rcd_sn,
		      s32 *sync_size,
		      int *resync_sgs)
{
	int tcp_payload_offset = skb_transport_offset(skb) + tcp_hdrlen(skb);
	int payload_len = skb->len - tcp_payload_offset;
	u32 tcp_seq = ntohl(tcp_hdr(skb)->seq);
	struct tls_record_info *record;
	unsigned long flags;
	int remaining;
	int i;

	spin_lock_irqsave(&ctx->lock, flags);
	record = tls_get_record(ctx, tcp_seq, rcd_sn);
	if (!record) {
		spin_unlock_irqrestore(&ctx->lock, flags);
		return -EINVAL;
	}

	*sync_size = tcp_seq - tls_record_start_seq(record);
	if (*sync_size < 0) {
		int is_start_marker = tls_record_is_start_marker(record);

		spin_unlock_irqrestore(&ctx->lock, flags);
		/* This should only occur if the relevant record was
		 * already acked. In that case it should be ok
		 * to drop the packet and avoid retransmission.
		 *
		 * There is a corner case where the packet contains
		 * both an acked and a non-acked record.
		 * We currently don't handle that case and rely
		 * on TCP to retranmit a packet that doesn't contain
		 * already acked payload.
		 */
		if (!is_start_marker)
			*sync_size = 0;
		return -EINVAL;
	}

	remaining = *sync_size;
	for (i = 0; remaining > 0; i++) {
		skb_frag_t *frag = &record->frags[i];

		__skb_frag_ref(frag);
		sg_set_page(sg_in + i, skb_frag_page(frag),
			    skb_frag_size(frag), skb_frag_off(frag));

		remaining -= skb_frag_size(frag);

		if (remaining < 0)
			sg_in[i].length += remaining;
	}
	*resync_sgs = i;

	spin_unlock_irqrestore(&ctx->lock, flags);
	if (skb_to_sgvec(skb, &sg_in[i], tcp_payload_offset, payload_len) < 0)
		return -EINVAL;

	return 0;
}

static void fill_sg_out(struct scatterlist sg_out[3], void *buf,
			struct tls_context *tls_ctx,
			struct sk_buff *nskb,
			int tcp_payload_offset,
			int payload_len,
			int sync_size,
			void *dummy_buf)
{
	sg_set_buf(&sg_out[0], dummy_buf, sync_size);
	sg_set_buf(&sg_out[1], nskb->data + tcp_payload_offset, payload_len);
	/* Add room for authentication tag produced by crypto */
	dummy_buf += sync_size;
	sg_set_buf(&sg_out[2], dummy_buf, TLS_CIPHER_AES_GCM_128_TAG_SIZE);
}

static struct sk_buff *tls_enc_skb(struct tls_context *tls_ctx,
				   struct scatterlist sg_out[3],
				   struct scatterlist *sg_in,
				   struct sk_buff *skb,
				   s32 sync_size, u64 rcd_sn)
{
	int tcp_payload_offset = skb_transport_offset(skb) + tcp_hdrlen(skb);
	struct tls_offload_context_tx *ctx = tls_offload_ctx_tx(tls_ctx);
	int payload_len = skb->len - tcp_payload_offset;
	void *buf, *iv, *aad, *dummy_buf;
	struct aead_request *aead_req;
	struct sk_buff *nskb = NULL;
	int buf_len;

	aead_req = tls_alloc_aead_request(ctx->aead_send, GFP_ATOMIC);
	if (!aead_req)
		return NULL;

	buf_len = TLS_CIPHER_AES_GCM_128_SALT_SIZE +
		  TLS_CIPHER_AES_GCM_128_IV_SIZE +
		  TLS_AAD_SPACE_SIZE +
		  sync_size +
		  TLS_CIPHER_AES_GCM_128_TAG_SIZE;
	buf = kmalloc(buf_len, GFP_ATOMIC);
	if (!buf)
		goto free_req;

	iv = buf;
	memcpy(iv, tls_ctx->crypto_send.aes_gcm_128.salt,
	       TLS_CIPHER_AES_GCM_128_SALT_SIZE);
	aad = buf + TLS_CIPHER_AES_GCM_128_SALT_SIZE +
	      TLS_CIPHER_AES_GCM_128_IV_SIZE;
	dummy_buf = aad + TLS_AAD_SPACE_SIZE;

	nskb = alloc_skb(skb_headroom(skb) + skb->len, GFP_ATOMIC);
	if (!nskb)
		goto free_buf;

	skb_reserve(nskb, skb_headroom(skb));

	fill_sg_out(sg_out, buf, tls_ctx, nskb, tcp_payload_offset,
		    payload_len, sync_size, dummy_buf);

	if (tls_enc_records(aead_req, ctx->aead_send, sg_in, sg_out, aad, iv,
			    rcd_sn, sync_size + payload_len) < 0)
		goto free_nskb;

	complete_skb(nskb, skb, tcp_payload_offset);

	/* validate_xmit_skb_list assumes that if the skb wasn't segmented
	 * nskb->prev will point to the skb itself
	 */
	nskb->prev = nskb;

free_buf:
	kfree(buf);
free_req:
	kfree(aead_req);
	return nskb;
free_nskb:
	kfree_skb(nskb);
	nskb = NULL;
	goto free_buf;
}

static struct sk_buff *tls_sw_fallback(struct sock *sk, struct sk_buff *skb)
{
	int tcp_payload_offset = skb_transport_offset(skb) + tcp_hdrlen(skb);
	struct tls_context *tls_ctx = tls_get_ctx(sk);
	struct tls_offload_context_tx *ctx = tls_offload_ctx_tx(tls_ctx);
	int payload_len = skb->len - tcp_payload_offset;
	struct scatterlist *sg_in, sg_out[3];
	struct sk_buff *nskb = NULL;
	int sg_in_max_elements;
	int resync_sgs = 0;
	s32 sync_size = 0;
	u64 rcd_sn;

	/* worst case is:
	 * MAX_SKB_FRAGS in tls_record_info
	 * MAX_SKB_FRAGS + 1 in SKB head and frags.
	 */
	sg_in_max_elements = 2 * MAX_SKB_FRAGS + 1;

	if (!payload_len)
		return skb;

	sg_in = kmalloc_array(sg_in_max_elements, sizeof(*sg_in), GFP_ATOMIC);
	if (!sg_in)
		goto free_orig;

	sg_init_table(sg_in, sg_in_max_elements);
	sg_init_table(sg_out, ARRAY_SIZE(sg_out));

	if (fill_sg_in(sg_in, skb, ctx, &rcd_sn, &sync_size, &resync_sgs)) {
		/* bypass packets before kernel TLS socket option was set */
		if (sync_size < 0 && payload_len <= -sync_size)
			nskb = skb_get(skb);
		goto put_sg;
	}

	nskb = tls_enc_skb(tls_ctx, sg_out, sg_in, skb, sync_size, rcd_sn);

put_sg:
	while (resync_sgs)
		put_page(sg_page(&sg_in[--resync_sgs]));
	kfree(sg_in);
free_orig:
	if (nskb)
		consume_skb(skb);
	else
		kfree_skb(skb);
	return nskb;
}

struct sk_buff *tls_validate_xmit_skb(struct sock *sk,
				      struct net_device *dev,
				      struct sk_buff *skb)
{
	if (dev == tls_get_ctx(sk)->netdev)
		return skb;

	return tls_sw_fallback(sk, skb);
}
EXPORT_SYMBOL_GPL(tls_validate_xmit_skb);

struct sk_buff *tls_encrypt_skb(struct sk_buff *skb)
{
	return tls_sw_fallback(skb->sk, skb);
}
EXPORT_SYMBOL_GPL(tls_encrypt_skb);

int tls_sw_fallback_init(struct sock *sk,
			 struct tls_offload_context_tx *offload_ctx,
			 struct tls_crypto_info *crypto_info)
{
	const u8 *key;
	int rc;

	offload_ctx->aead_send =
	    crypto_alloc_aead("gcm(aes)", 0, CRYPTO_ALG_ASYNC);
	if (IS_ERR(offload_ctx->aead_send)) {
		rc = PTR_ERR(offload_ctx->aead_send);
		pr_err_ratelimited("crypto_alloc_aead failed rc=%d\n", rc);
		offload_ctx->aead_send = NULL;
		goto err_out;
	}

	key = ((struct tls12_crypto_info_aes_gcm_128 *)crypto_info)->key;

	rc = crypto_aead_setkey(offload_ctx->aead_send, key,
				TLS_CIPHER_AES_GCM_128_KEY_SIZE);
	if (rc)
		goto free_aead;

	rc = crypto_aead_setauthsize(offload_ctx->aead_send,
				     TLS_CIPHER_AES_GCM_128_TAG_SIZE);
	if (rc)
		goto free_aead;

	return 0;
free_aead:
	crypto_free_aead(offload_ctx->aead_send);
err_out:
	return rc;
}