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1/* Copyright (c) 2018, Mellanox Technologies All rights reserved.
2 *
3 * This software is available to you under a choice of one of two
4 * licenses. You may choose to be licensed under the terms of the GNU
5 * General Public License (GPL) Version 2, available from the file
6 * COPYING in the main directory of this source tree, or the
7 * OpenIB.org BSD license below:
8 *
9 * Redistribution and use in source and binary forms, with or
10 * without modification, are permitted provided that the following
11 * conditions are met:
12 *
13 * - Redistributions of source code must retain the above
14 * copyright notice, this list of conditions and the following
15 * disclaimer.
16 *
17 * - Redistributions in binary form must reproduce the above
18 * copyright notice, this list of conditions and the following
19 * disclaimer in the documentation and/or other materials
20 * provided with the distribution.
21 *
22 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
23 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
24 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
25 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
26 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
27 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
28 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
29 * SOFTWARE.
30 */
31
32#include <net/tls.h>
33#include <crypto/aead.h>
34#include <crypto/scatterwalk.h>
35#include <net/ip6_checksum.h>
36
37static void chain_to_walk(struct scatterlist *sg, struct scatter_walk *walk)
38{
39 struct scatterlist *src = walk->sg;
40 int diff = walk->offset - src->offset;
41
42 sg_set_page(sg, sg_page(src),
43 src->length - diff, walk->offset);
44
45 scatterwalk_crypto_chain(sg, sg_next(src), 2);
46}
47
48static int tls_enc_record(struct aead_request *aead_req,
49 struct crypto_aead *aead, char *aad,
50 char *iv, __be64 rcd_sn,
51 struct scatter_walk *in,
52 struct scatter_walk *out, int *in_len)
53{
54 unsigned char buf[TLS_HEADER_SIZE + TLS_CIPHER_AES_GCM_128_IV_SIZE];
55 struct scatterlist sg_in[3];
56 struct scatterlist sg_out[3];
57 u16 len;
58 int rc;
59
60 len = min_t(int, *in_len, ARRAY_SIZE(buf));
61
62 scatterwalk_copychunks(buf, in, len, 0);
63 scatterwalk_copychunks(buf, out, len, 1);
64
65 *in_len -= len;
66 if (!*in_len)
67 return 0;
68
69 scatterwalk_pagedone(in, 0, 1);
70 scatterwalk_pagedone(out, 1, 1);
71
72 len = buf[4] | (buf[3] << 8);
73 len -= TLS_CIPHER_AES_GCM_128_IV_SIZE;
74
75 tls_make_aad(aad, len - TLS_CIPHER_AES_GCM_128_TAG_SIZE,
76 (char *)&rcd_sn, sizeof(rcd_sn), buf[0],
77 TLS_1_2_VERSION);
78
79 memcpy(iv + TLS_CIPHER_AES_GCM_128_SALT_SIZE, buf + TLS_HEADER_SIZE,
80 TLS_CIPHER_AES_GCM_128_IV_SIZE);
81
82 sg_init_table(sg_in, ARRAY_SIZE(sg_in));
83 sg_init_table(sg_out, ARRAY_SIZE(sg_out));
84 sg_set_buf(sg_in, aad, TLS_AAD_SPACE_SIZE);
85 sg_set_buf(sg_out, aad, TLS_AAD_SPACE_SIZE);
86 chain_to_walk(sg_in + 1, in);
87 chain_to_walk(sg_out + 1, out);
88
89 *in_len -= len;
90 if (*in_len < 0) {
91 *in_len += TLS_CIPHER_AES_GCM_128_TAG_SIZE;
92 /* the input buffer doesn't contain the entire record.
93 * trim len accordingly. The resulting authentication tag
94 * will contain garbage, but we don't care, so we won't
95 * include any of it in the output skb
96 * Note that we assume the output buffer length
97 * is larger then input buffer length + tag size
98 */
99 if (*in_len < 0)
100 len += *in_len;
101
102 *in_len = 0;
103 }
104
105 if (*in_len) {
106 scatterwalk_copychunks(NULL, in, len, 2);
107 scatterwalk_pagedone(in, 0, 1);
108 scatterwalk_copychunks(NULL, out, len, 2);
109 scatterwalk_pagedone(out, 1, 1);
110 }
111
112 len -= TLS_CIPHER_AES_GCM_128_TAG_SIZE;
113 aead_request_set_crypt(aead_req, sg_in, sg_out, len, iv);
114
115 rc = crypto_aead_encrypt(aead_req);
116
117 return rc;
118}
119
120static void tls_init_aead_request(struct aead_request *aead_req,
121 struct crypto_aead *aead)
122{
123 aead_request_set_tfm(aead_req, aead);
124 aead_request_set_ad(aead_req, TLS_AAD_SPACE_SIZE);
125}
126
127static struct aead_request *tls_alloc_aead_request(struct crypto_aead *aead,
128 gfp_t flags)
129{
130 unsigned int req_size = sizeof(struct aead_request) +
131 crypto_aead_reqsize(aead);
132 struct aead_request *aead_req;
133
134 aead_req = kzalloc(req_size, flags);
135 if (aead_req)
136 tls_init_aead_request(aead_req, aead);
137 return aead_req;
138}
139
140static int tls_enc_records(struct aead_request *aead_req,
141 struct crypto_aead *aead, struct scatterlist *sg_in,
142 struct scatterlist *sg_out, char *aad, char *iv,
143 u64 rcd_sn, int len)
144{
145 struct scatter_walk out, in;
146 int rc;
147
148 scatterwalk_start(&in, sg_in);
149 scatterwalk_start(&out, sg_out);
150
151 do {
152 rc = tls_enc_record(aead_req, aead, aad, iv,
153 cpu_to_be64(rcd_sn), &in, &out, &len);
154 rcd_sn++;
155
156 } while (rc == 0 && len);
157
158 scatterwalk_done(&in, 0, 0);
159 scatterwalk_done(&out, 1, 0);
160
161 return rc;
162}
163
164/* Can't use icsk->icsk_af_ops->send_check here because the ip addresses
165 * might have been changed by NAT.
166 */
167static void update_chksum(struct sk_buff *skb, int headln)
168{
169 struct tcphdr *th = tcp_hdr(skb);
170 int datalen = skb->len - headln;
171 const struct ipv6hdr *ipv6h;
172 const struct iphdr *iph;
173
174 /* We only changed the payload so if we are using partial we don't
175 * need to update anything.
176 */
177 if (likely(skb->ip_summed == CHECKSUM_PARTIAL))
178 return;
179
180 skb->ip_summed = CHECKSUM_PARTIAL;
181 skb->csum_start = skb_transport_header(skb) - skb->head;
182 skb->csum_offset = offsetof(struct tcphdr, check);
183
184 if (skb->sk->sk_family == AF_INET6) {
185 ipv6h = ipv6_hdr(skb);
186 th->check = ~csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr,
187 datalen, IPPROTO_TCP, 0);
188 } else {
189 iph = ip_hdr(skb);
190 th->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr, datalen,
191 IPPROTO_TCP, 0);
192 }
193}
194
195static void complete_skb(struct sk_buff *nskb, struct sk_buff *skb, int headln)
196{
197 struct sock *sk = skb->sk;
198 int delta;
199
200 skb_copy_header(nskb, skb);
201
202 skb_put(nskb, skb->len);
203 memcpy(nskb->data, skb->data, headln);
204
205 nskb->destructor = skb->destructor;
206 nskb->sk = sk;
207 skb->destructor = NULL;
208 skb->sk = NULL;
209
210 update_chksum(nskb, headln);
211
212 /* sock_efree means skb must gone through skb_orphan_partial() */
213 if (nskb->destructor == sock_efree)
214 return;
215
216 delta = nskb->truesize - skb->truesize;
217 if (likely(delta < 0))
218 WARN_ON_ONCE(refcount_sub_and_test(-delta, &sk->sk_wmem_alloc));
219 else if (delta)
220 refcount_add(delta, &sk->sk_wmem_alloc);
221}
222
223/* This function may be called after the user socket is already
224 * closed so make sure we don't use anything freed during
225 * tls_sk_proto_close here
226 */
227
228static int fill_sg_in(struct scatterlist *sg_in,
229 struct sk_buff *skb,
230 struct tls_offload_context_tx *ctx,
231 u64 *rcd_sn,
232 s32 *sync_size,
233 int *resync_sgs)
234{
235 int tcp_payload_offset = skb_transport_offset(skb) + tcp_hdrlen(skb);
236 int payload_len = skb->len - tcp_payload_offset;
237 u32 tcp_seq = ntohl(tcp_hdr(skb)->seq);
238 struct tls_record_info *record;
239 unsigned long flags;
240 int remaining;
241 int i;
242
243 spin_lock_irqsave(&ctx->lock, flags);
244 record = tls_get_record(ctx, tcp_seq, rcd_sn);
245 if (!record) {
246 spin_unlock_irqrestore(&ctx->lock, flags);
247 return -EINVAL;
248 }
249
250 *sync_size = tcp_seq - tls_record_start_seq(record);
251 if (*sync_size < 0) {
252 int is_start_marker = tls_record_is_start_marker(record);
253
254 spin_unlock_irqrestore(&ctx->lock, flags);
255 /* This should only occur if the relevant record was
256 * already acked. In that case it should be ok
257 * to drop the packet and avoid retransmission.
258 *
259 * There is a corner case where the packet contains
260 * both an acked and a non-acked record.
261 * We currently don't handle that case and rely
262 * on TCP to retranmit a packet that doesn't contain
263 * already acked payload.
264 */
265 if (!is_start_marker)
266 *sync_size = 0;
267 return -EINVAL;
268 }
269
270 remaining = *sync_size;
271 for (i = 0; remaining > 0; i++) {
272 skb_frag_t *frag = &record->frags[i];
273
274 __skb_frag_ref(frag);
275 sg_set_page(sg_in + i, skb_frag_page(frag),
276 skb_frag_size(frag), skb_frag_off(frag));
277
278 remaining -= skb_frag_size(frag);
279
280 if (remaining < 0)
281 sg_in[i].length += remaining;
282 }
283 *resync_sgs = i;
284
285 spin_unlock_irqrestore(&ctx->lock, flags);
286 if (skb_to_sgvec(skb, &sg_in[i], tcp_payload_offset, payload_len) < 0)
287 return -EINVAL;
288
289 return 0;
290}
291
292static void fill_sg_out(struct scatterlist sg_out[3], void *buf,
293 struct tls_context *tls_ctx,
294 struct sk_buff *nskb,
295 int tcp_payload_offset,
296 int payload_len,
297 int sync_size,
298 void *dummy_buf)
299{
300 sg_set_buf(&sg_out[0], dummy_buf, sync_size);
301 sg_set_buf(&sg_out[1], nskb->data + tcp_payload_offset, payload_len);
302 /* Add room for authentication tag produced by crypto */
303 dummy_buf += sync_size;
304 sg_set_buf(&sg_out[2], dummy_buf, TLS_CIPHER_AES_GCM_128_TAG_SIZE);
305}
306
307static struct sk_buff *tls_enc_skb(struct tls_context *tls_ctx,
308 struct scatterlist sg_out[3],
309 struct scatterlist *sg_in,
310 struct sk_buff *skb,
311 s32 sync_size, u64 rcd_sn)
312{
313 int tcp_payload_offset = skb_transport_offset(skb) + tcp_hdrlen(skb);
314 struct tls_offload_context_tx *ctx = tls_offload_ctx_tx(tls_ctx);
315 int payload_len = skb->len - tcp_payload_offset;
316 void *buf, *iv, *aad, *dummy_buf;
317 struct aead_request *aead_req;
318 struct sk_buff *nskb = NULL;
319 int buf_len;
320
321 aead_req = tls_alloc_aead_request(ctx->aead_send, GFP_ATOMIC);
322 if (!aead_req)
323 return NULL;
324
325 buf_len = TLS_CIPHER_AES_GCM_128_SALT_SIZE +
326 TLS_CIPHER_AES_GCM_128_IV_SIZE +
327 TLS_AAD_SPACE_SIZE +
328 sync_size +
329 TLS_CIPHER_AES_GCM_128_TAG_SIZE;
330 buf = kmalloc(buf_len, GFP_ATOMIC);
331 if (!buf)
332 goto free_req;
333
334 iv = buf;
335 memcpy(iv, tls_ctx->crypto_send.aes_gcm_128.salt,
336 TLS_CIPHER_AES_GCM_128_SALT_SIZE);
337 aad = buf + TLS_CIPHER_AES_GCM_128_SALT_SIZE +
338 TLS_CIPHER_AES_GCM_128_IV_SIZE;
339 dummy_buf = aad + TLS_AAD_SPACE_SIZE;
340
341 nskb = alloc_skb(skb_headroom(skb) + skb->len, GFP_ATOMIC);
342 if (!nskb)
343 goto free_buf;
344
345 skb_reserve(nskb, skb_headroom(skb));
346
347 fill_sg_out(sg_out, buf, tls_ctx, nskb, tcp_payload_offset,
348 payload_len, sync_size, dummy_buf);
349
350 if (tls_enc_records(aead_req, ctx->aead_send, sg_in, sg_out, aad, iv,
351 rcd_sn, sync_size + payload_len) < 0)
352 goto free_nskb;
353
354 complete_skb(nskb, skb, tcp_payload_offset);
355
356 /* validate_xmit_skb_list assumes that if the skb wasn't segmented
357 * nskb->prev will point to the skb itself
358 */
359 nskb->prev = nskb;
360
361free_buf:
362 kfree(buf);
363free_req:
364 kfree(aead_req);
365 return nskb;
366free_nskb:
367 kfree_skb(nskb);
368 nskb = NULL;
369 goto free_buf;
370}
371
372static struct sk_buff *tls_sw_fallback(struct sock *sk, struct sk_buff *skb)
373{
374 int tcp_payload_offset = skb_transport_offset(skb) + tcp_hdrlen(skb);
375 struct tls_context *tls_ctx = tls_get_ctx(sk);
376 struct tls_offload_context_tx *ctx = tls_offload_ctx_tx(tls_ctx);
377 int payload_len = skb->len - tcp_payload_offset;
378 struct scatterlist *sg_in, sg_out[3];
379 struct sk_buff *nskb = NULL;
380 int sg_in_max_elements;
381 int resync_sgs = 0;
382 s32 sync_size = 0;
383 u64 rcd_sn;
384
385 /* worst case is:
386 * MAX_SKB_FRAGS in tls_record_info
387 * MAX_SKB_FRAGS + 1 in SKB head and frags.
388 */
389 sg_in_max_elements = 2 * MAX_SKB_FRAGS + 1;
390
391 if (!payload_len)
392 return skb;
393
394 sg_in = kmalloc_array(sg_in_max_elements, sizeof(*sg_in), GFP_ATOMIC);
395 if (!sg_in)
396 goto free_orig;
397
398 sg_init_table(sg_in, sg_in_max_elements);
399 sg_init_table(sg_out, ARRAY_SIZE(sg_out));
400
401 if (fill_sg_in(sg_in, skb, ctx, &rcd_sn, &sync_size, &resync_sgs)) {
402 /* bypass packets before kernel TLS socket option was set */
403 if (sync_size < 0 && payload_len <= -sync_size)
404 nskb = skb_get(skb);
405 goto put_sg;
406 }
407
408 nskb = tls_enc_skb(tls_ctx, sg_out, sg_in, skb, sync_size, rcd_sn);
409
410put_sg:
411 while (resync_sgs)
412 put_page(sg_page(&sg_in[--resync_sgs]));
413 kfree(sg_in);
414free_orig:
415 if (nskb)
416 consume_skb(skb);
417 else
418 kfree_skb(skb);
419 return nskb;
420}
421
422struct sk_buff *tls_validate_xmit_skb(struct sock *sk,
423 struct net_device *dev,
424 struct sk_buff *skb)
425{
426 if (dev == tls_get_ctx(sk)->netdev)
427 return skb;
428
429 return tls_sw_fallback(sk, skb);
430}
431EXPORT_SYMBOL_GPL(tls_validate_xmit_skb);
432
433struct sk_buff *tls_encrypt_skb(struct sk_buff *skb)
434{
435 return tls_sw_fallback(skb->sk, skb);
436}
437EXPORT_SYMBOL_GPL(tls_encrypt_skb);
438
439int tls_sw_fallback_init(struct sock *sk,
440 struct tls_offload_context_tx *offload_ctx,
441 struct tls_crypto_info *crypto_info)
442{
443 const u8 *key;
444 int rc;
445
446 offload_ctx->aead_send =
447 crypto_alloc_aead("gcm(aes)", 0, CRYPTO_ALG_ASYNC);
448 if (IS_ERR(offload_ctx->aead_send)) {
449 rc = PTR_ERR(offload_ctx->aead_send);
450 pr_err_ratelimited("crypto_alloc_aead failed rc=%d\n", rc);
451 offload_ctx->aead_send = NULL;
452 goto err_out;
453 }
454
455 key = ((struct tls12_crypto_info_aes_gcm_128 *)crypto_info)->key;
456
457 rc = crypto_aead_setkey(offload_ctx->aead_send, key,
458 TLS_CIPHER_AES_GCM_128_KEY_SIZE);
459 if (rc)
460 goto free_aead;
461
462 rc = crypto_aead_setauthsize(offload_ctx->aead_send,
463 TLS_CIPHER_AES_GCM_128_TAG_SIZE);
464 if (rc)
465 goto free_aead;
466
467 return 0;
468free_aead:
469 crypto_free_aead(offload_ctx->aead_send);
470err_out:
471 return rc;
472}