tls: Add rx inline crypto offload
[sfrench/cifs-2.6.git] / net / tls / tls_device_fallback.c
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
37 static 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), 0, 2);
46 }
47
48 static 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
78         memcpy(iv + TLS_CIPHER_AES_GCM_128_SALT_SIZE, buf + TLS_HEADER_SIZE,
79                TLS_CIPHER_AES_GCM_128_IV_SIZE);
80
81         sg_init_table(sg_in, ARRAY_SIZE(sg_in));
82         sg_init_table(sg_out, ARRAY_SIZE(sg_out));
83         sg_set_buf(sg_in, aad, TLS_AAD_SPACE_SIZE);
84         sg_set_buf(sg_out, aad, TLS_AAD_SPACE_SIZE);
85         chain_to_walk(sg_in + 1, in);
86         chain_to_walk(sg_out + 1, out);
87
88         *in_len -= len;
89         if (*in_len < 0) {
90                 *in_len += TLS_CIPHER_AES_GCM_128_TAG_SIZE;
91                 /* the input buffer doesn't contain the entire record.
92                  * trim len accordingly. The resulting authentication tag
93                  * will contain garbage, but we don't care, so we won't
94                  * include any of it in the output skb
95                  * Note that we assume the output buffer length
96                  * is larger then input buffer length + tag size
97                  */
98                 if (*in_len < 0)
99                         len += *in_len;
100
101                 *in_len = 0;
102         }
103
104         if (*in_len) {
105                 scatterwalk_copychunks(NULL, in, len, 2);
106                 scatterwalk_pagedone(in, 0, 1);
107                 scatterwalk_copychunks(NULL, out, len, 2);
108                 scatterwalk_pagedone(out, 1, 1);
109         }
110
111         len -= TLS_CIPHER_AES_GCM_128_TAG_SIZE;
112         aead_request_set_crypt(aead_req, sg_in, sg_out, len, iv);
113
114         rc = crypto_aead_encrypt(aead_req);
115
116         return rc;
117 }
118
119 static void tls_init_aead_request(struct aead_request *aead_req,
120                                   struct crypto_aead *aead)
121 {
122         aead_request_set_tfm(aead_req, aead);
123         aead_request_set_ad(aead_req, TLS_AAD_SPACE_SIZE);
124 }
125
126 static struct aead_request *tls_alloc_aead_request(struct crypto_aead *aead,
127                                                    gfp_t flags)
128 {
129         unsigned int req_size = sizeof(struct aead_request) +
130                 crypto_aead_reqsize(aead);
131         struct aead_request *aead_req;
132
133         aead_req = kzalloc(req_size, flags);
134         if (aead_req)
135                 tls_init_aead_request(aead_req, aead);
136         return aead_req;
137 }
138
139 static int tls_enc_records(struct aead_request *aead_req,
140                            struct crypto_aead *aead, struct scatterlist *sg_in,
141                            struct scatterlist *sg_out, char *aad, char *iv,
142                            u64 rcd_sn, int len)
143 {
144         struct scatter_walk out, in;
145         int rc;
146
147         scatterwalk_start(&in, sg_in);
148         scatterwalk_start(&out, sg_out);
149
150         do {
151                 rc = tls_enc_record(aead_req, aead, aad, iv,
152                                     cpu_to_be64(rcd_sn), &in, &out, &len);
153                 rcd_sn++;
154
155         } while (rc == 0 && len);
156
157         scatterwalk_done(&in, 0, 0);
158         scatterwalk_done(&out, 1, 0);
159
160         return rc;
161 }
162
163 /* Can't use icsk->icsk_af_ops->send_check here because the ip addresses
164  * might have been changed by NAT.
165  */
166 static void update_chksum(struct sk_buff *skb, int headln)
167 {
168         struct tcphdr *th = tcp_hdr(skb);
169         int datalen = skb->len - headln;
170         const struct ipv6hdr *ipv6h;
171         const struct iphdr *iph;
172
173         /* We only changed the payload so if we are using partial we don't
174          * need to update anything.
175          */
176         if (likely(skb->ip_summed == CHECKSUM_PARTIAL))
177                 return;
178
179         skb->ip_summed = CHECKSUM_PARTIAL;
180         skb->csum_start = skb_transport_header(skb) - skb->head;
181         skb->csum_offset = offsetof(struct tcphdr, check);
182
183         if (skb->sk->sk_family == AF_INET6) {
184                 ipv6h = ipv6_hdr(skb);
185                 th->check = ~csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr,
186                                              datalen, IPPROTO_TCP, 0);
187         } else {
188                 iph = ip_hdr(skb);
189                 th->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr, datalen,
190                                                IPPROTO_TCP, 0);
191         }
192 }
193
194 static void complete_skb(struct sk_buff *nskb, struct sk_buff *skb, int headln)
195 {
196         skb_copy_header(nskb, skb);
197
198         skb_put(nskb, skb->len);
199         memcpy(nskb->data, skb->data, headln);
200         update_chksum(nskb, headln);
201
202         nskb->destructor = skb->destructor;
203         nskb->sk = skb->sk;
204         skb->destructor = NULL;
205         skb->sk = NULL;
206         refcount_add(nskb->truesize - skb->truesize,
207                      &nskb->sk->sk_wmem_alloc);
208 }
209
210 /* This function may be called after the user socket is already
211  * closed so make sure we don't use anything freed during
212  * tls_sk_proto_close here
213  */
214
215 static int fill_sg_in(struct scatterlist *sg_in,
216                       struct sk_buff *skb,
217                       struct tls_offload_context_tx *ctx,
218                       u64 *rcd_sn,
219                       s32 *sync_size,
220                       int *resync_sgs)
221 {
222         int tcp_payload_offset = skb_transport_offset(skb) + tcp_hdrlen(skb);
223         int payload_len = skb->len - tcp_payload_offset;
224         u32 tcp_seq = ntohl(tcp_hdr(skb)->seq);
225         struct tls_record_info *record;
226         unsigned long flags;
227         int remaining;
228         int i;
229
230         spin_lock_irqsave(&ctx->lock, flags);
231         record = tls_get_record(ctx, tcp_seq, rcd_sn);
232         if (!record) {
233                 spin_unlock_irqrestore(&ctx->lock, flags);
234                 WARN(1, "Record not found for seq %u\n", tcp_seq);
235                 return -EINVAL;
236         }
237
238         *sync_size = tcp_seq - tls_record_start_seq(record);
239         if (*sync_size < 0) {
240                 int is_start_marker = tls_record_is_start_marker(record);
241
242                 spin_unlock_irqrestore(&ctx->lock, flags);
243                 /* This should only occur if the relevant record was
244                  * already acked. In that case it should be ok
245                  * to drop the packet and avoid retransmission.
246                  *
247                  * There is a corner case where the packet contains
248                  * both an acked and a non-acked record.
249                  * We currently don't handle that case and rely
250                  * on TCP to retranmit a packet that doesn't contain
251                  * already acked payload.
252                  */
253                 if (!is_start_marker)
254                         *sync_size = 0;
255                 return -EINVAL;
256         }
257
258         remaining = *sync_size;
259         for (i = 0; remaining > 0; i++) {
260                 skb_frag_t *frag = &record->frags[i];
261
262                 __skb_frag_ref(frag);
263                 sg_set_page(sg_in + i, skb_frag_page(frag),
264                             skb_frag_size(frag), frag->page_offset);
265
266                 remaining -= skb_frag_size(frag);
267
268                 if (remaining < 0)
269                         sg_in[i].length += remaining;
270         }
271         *resync_sgs = i;
272
273         spin_unlock_irqrestore(&ctx->lock, flags);
274         if (skb_to_sgvec(skb, &sg_in[i], tcp_payload_offset, payload_len) < 0)
275                 return -EINVAL;
276
277         return 0;
278 }
279
280 static void fill_sg_out(struct scatterlist sg_out[3], void *buf,
281                         struct tls_context *tls_ctx,
282                         struct sk_buff *nskb,
283                         int tcp_payload_offset,
284                         int payload_len,
285                         int sync_size,
286                         void *dummy_buf)
287 {
288         sg_set_buf(&sg_out[0], dummy_buf, sync_size);
289         sg_set_buf(&sg_out[1], nskb->data + tcp_payload_offset, payload_len);
290         /* Add room for authentication tag produced by crypto */
291         dummy_buf += sync_size;
292         sg_set_buf(&sg_out[2], dummy_buf, TLS_CIPHER_AES_GCM_128_TAG_SIZE);
293 }
294
295 static struct sk_buff *tls_enc_skb(struct tls_context *tls_ctx,
296                                    struct scatterlist sg_out[3],
297                                    struct scatterlist *sg_in,
298                                    struct sk_buff *skb,
299                                    s32 sync_size, u64 rcd_sn)
300 {
301         int tcp_payload_offset = skb_transport_offset(skb) + tcp_hdrlen(skb);
302         struct tls_offload_context_tx *ctx = tls_offload_ctx_tx(tls_ctx);
303         int payload_len = skb->len - tcp_payload_offset;
304         void *buf, *iv, *aad, *dummy_buf;
305         struct aead_request *aead_req;
306         struct sk_buff *nskb = NULL;
307         int buf_len;
308
309         aead_req = tls_alloc_aead_request(ctx->aead_send, GFP_ATOMIC);
310         if (!aead_req)
311                 return NULL;
312
313         buf_len = TLS_CIPHER_AES_GCM_128_SALT_SIZE +
314                   TLS_CIPHER_AES_GCM_128_IV_SIZE +
315                   TLS_AAD_SPACE_SIZE +
316                   sync_size +
317                   TLS_CIPHER_AES_GCM_128_TAG_SIZE;
318         buf = kmalloc(buf_len, GFP_ATOMIC);
319         if (!buf)
320                 goto free_req;
321
322         iv = buf;
323         memcpy(iv, tls_ctx->crypto_send_aes_gcm_128.salt,
324                TLS_CIPHER_AES_GCM_128_SALT_SIZE);
325         aad = buf + TLS_CIPHER_AES_GCM_128_SALT_SIZE +
326               TLS_CIPHER_AES_GCM_128_IV_SIZE;
327         dummy_buf = aad + TLS_AAD_SPACE_SIZE;
328
329         nskb = alloc_skb(skb_headroom(skb) + skb->len, GFP_ATOMIC);
330         if (!nskb)
331                 goto free_buf;
332
333         skb_reserve(nskb, skb_headroom(skb));
334
335         fill_sg_out(sg_out, buf, tls_ctx, nskb, tcp_payload_offset,
336                     payload_len, sync_size, dummy_buf);
337
338         if (tls_enc_records(aead_req, ctx->aead_send, sg_in, sg_out, aad, iv,
339                             rcd_sn, sync_size + payload_len) < 0)
340                 goto free_nskb;
341
342         complete_skb(nskb, skb, tcp_payload_offset);
343
344         /* validate_xmit_skb_list assumes that if the skb wasn't segmented
345          * nskb->prev will point to the skb itself
346          */
347         nskb->prev = nskb;
348
349 free_buf:
350         kfree(buf);
351 free_req:
352         kfree(aead_req);
353         return nskb;
354 free_nskb:
355         kfree_skb(nskb);
356         nskb = NULL;
357         goto free_buf;
358 }
359
360 static struct sk_buff *tls_sw_fallback(struct sock *sk, struct sk_buff *skb)
361 {
362         int tcp_payload_offset = skb_transport_offset(skb) + tcp_hdrlen(skb);
363         struct tls_context *tls_ctx = tls_get_ctx(sk);
364         struct tls_offload_context_tx *ctx = tls_offload_ctx_tx(tls_ctx);
365         int payload_len = skb->len - tcp_payload_offset;
366         struct scatterlist *sg_in, sg_out[3];
367         struct sk_buff *nskb = NULL;
368         int sg_in_max_elements;
369         int resync_sgs = 0;
370         s32 sync_size = 0;
371         u64 rcd_sn;
372
373         /* worst case is:
374          * MAX_SKB_FRAGS in tls_record_info
375          * MAX_SKB_FRAGS + 1 in SKB head and frags.
376          */
377         sg_in_max_elements = 2 * MAX_SKB_FRAGS + 1;
378
379         if (!payload_len)
380                 return skb;
381
382         sg_in = kmalloc_array(sg_in_max_elements, sizeof(*sg_in), GFP_ATOMIC);
383         if (!sg_in)
384                 goto free_orig;
385
386         sg_init_table(sg_in, sg_in_max_elements);
387         sg_init_table(sg_out, ARRAY_SIZE(sg_out));
388
389         if (fill_sg_in(sg_in, skb, ctx, &rcd_sn, &sync_size, &resync_sgs)) {
390                 /* bypass packets before kernel TLS socket option was set */
391                 if (sync_size < 0 && payload_len <= -sync_size)
392                         nskb = skb_get(skb);
393                 goto put_sg;
394         }
395
396         nskb = tls_enc_skb(tls_ctx, sg_out, sg_in, skb, sync_size, rcd_sn);
397
398 put_sg:
399         while (resync_sgs)
400                 put_page(sg_page(&sg_in[--resync_sgs]));
401         kfree(sg_in);
402 free_orig:
403         kfree_skb(skb);
404         return nskb;
405 }
406
407 struct sk_buff *tls_validate_xmit_skb(struct sock *sk,
408                                       struct net_device *dev,
409                                       struct sk_buff *skb)
410 {
411         if (dev == tls_get_ctx(sk)->netdev)
412                 return skb;
413
414         return tls_sw_fallback(sk, skb);
415 }
416 EXPORT_SYMBOL_GPL(tls_validate_xmit_skb);
417
418 int tls_sw_fallback_init(struct sock *sk,
419                          struct tls_offload_context_tx *offload_ctx,
420                          struct tls_crypto_info *crypto_info)
421 {
422         const u8 *key;
423         int rc;
424
425         offload_ctx->aead_send =
426             crypto_alloc_aead("gcm(aes)", 0, CRYPTO_ALG_ASYNC);
427         if (IS_ERR(offload_ctx->aead_send)) {
428                 rc = PTR_ERR(offload_ctx->aead_send);
429                 pr_err_ratelimited("crypto_alloc_aead failed rc=%d\n", rc);
430                 offload_ctx->aead_send = NULL;
431                 goto err_out;
432         }
433
434         key = ((struct tls12_crypto_info_aes_gcm_128 *)crypto_info)->key;
435
436         rc = crypto_aead_setkey(offload_ctx->aead_send, key,
437                                 TLS_CIPHER_AES_GCM_128_KEY_SIZE);
438         if (rc)
439                 goto free_aead;
440
441         rc = crypto_aead_setauthsize(offload_ctx->aead_send,
442                                      TLS_CIPHER_AES_GCM_128_TAG_SIZE);
443         if (rc)
444                 goto free_aead;
445
446         return 0;
447 free_aead:
448         crypto_free_aead(offload_ctx->aead_send);
449 err_out:
450         return rc;
451 }