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 *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 *ctx = tls_offload_ctx(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 *ctx = tls_offload_ctx(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 } 416 417 int tls_sw_fallback_init(struct sock *sk, 418 struct tls_offload_context *offload_ctx, 419 struct tls_crypto_info *crypto_info) 420 { 421 const u8 *key; 422 int rc; 423 424 offload_ctx->aead_send = 425 crypto_alloc_aead("gcm(aes)", 0, CRYPTO_ALG_ASYNC); 426 if (IS_ERR(offload_ctx->aead_send)) { 427 rc = PTR_ERR(offload_ctx->aead_send); 428 pr_err_ratelimited("crypto_alloc_aead failed rc=%d\n", rc); 429 offload_ctx->aead_send = NULL; 430 goto err_out; 431 } 432 433 key = ((struct tls12_crypto_info_aes_gcm_128 *)crypto_info)->key; 434 435 rc = crypto_aead_setkey(offload_ctx->aead_send, key, 436 TLS_CIPHER_AES_GCM_128_KEY_SIZE); 437 if (rc) 438 goto free_aead; 439 440 rc = crypto_aead_setauthsize(offload_ctx->aead_send, 441 TLS_CIPHER_AES_GCM_128_TAG_SIZE); 442 if (rc) 443 goto free_aead; 444 445 return 0; 446 free_aead: 447 crypto_free_aead(offload_ctx->aead_send); 448 err_out: 449 return rc; 450 } 451