1 #include <linux/err.h> 2 #include <linux/module.h> 3 #include <net/ip.h> 4 #include <net/xfrm.h> 5 #include <net/esp.h> 6 #include <linux/scatterlist.h> 7 #include <linux/crypto.h> 8 #include <linux/kernel.h> 9 #include <linux/pfkeyv2.h> 10 #include <linux/random.h> 11 #include <linux/spinlock.h> 12 #include <linux/in6.h> 13 #include <net/icmp.h> 14 #include <net/protocol.h> 15 #include <net/udp.h> 16 17 static int esp_output(struct xfrm_state *x, struct sk_buff *skb) 18 { 19 int err; 20 struct ip_esp_hdr *esph; 21 struct crypto_blkcipher *tfm; 22 struct blkcipher_desc desc; 23 struct esp_data *esp; 24 struct sk_buff *trailer; 25 u8 *tail; 26 int blksize; 27 int clen; 28 int alen; 29 int nfrags; 30 31 /* skb is pure payload to encrypt */ 32 33 err = -ENOMEM; 34 35 /* Round to block size */ 36 clen = skb->len; 37 38 esp = x->data; 39 alen = esp->auth.icv_trunc_len; 40 tfm = esp->conf.tfm; 41 desc.tfm = tfm; 42 desc.flags = 0; 43 blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4); 44 clen = ALIGN(clen + 2, blksize); 45 if (esp->conf.padlen) 46 clen = ALIGN(clen, esp->conf.padlen); 47 48 if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0) 49 goto error; 50 51 /* Fill padding... */ 52 tail = skb_tail_pointer(trailer); 53 do { 54 int i; 55 for (i=0; i<clen-skb->len - 2; i++) 56 tail[i] = i + 1; 57 } while (0); 58 tail[clen - skb->len - 2] = (clen - skb->len) - 2; 59 pskb_put(skb, trailer, clen - skb->len); 60 61 skb_push(skb, -skb_network_offset(skb)); 62 esph = ip_esp_hdr(skb); 63 *(skb_tail_pointer(trailer) - 1) = *skb_mac_header(skb); 64 *skb_mac_header(skb) = IPPROTO_ESP; 65 66 spin_lock_bh(&x->lock); 67 68 /* this is non-NULL only with UDP Encapsulation */ 69 if (x->encap) { 70 struct xfrm_encap_tmpl *encap = x->encap; 71 struct udphdr *uh; 72 __be32 *udpdata32; 73 74 uh = (struct udphdr *)esph; 75 uh->source = encap->encap_sport; 76 uh->dest = encap->encap_dport; 77 uh->len = htons(skb->len + alen - skb_transport_offset(skb)); 78 uh->check = 0; 79 80 switch (encap->encap_type) { 81 default: 82 case UDP_ENCAP_ESPINUDP: 83 esph = (struct ip_esp_hdr *)(uh + 1); 84 break; 85 case UDP_ENCAP_ESPINUDP_NON_IKE: 86 udpdata32 = (__be32 *)(uh + 1); 87 udpdata32[0] = udpdata32[1] = 0; 88 esph = (struct ip_esp_hdr *)(udpdata32 + 2); 89 break; 90 } 91 92 *skb_mac_header(skb) = IPPROTO_UDP; 93 } 94 95 esph->spi = x->id.spi; 96 esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq); 97 98 if (esp->conf.ivlen) { 99 if (unlikely(!esp->conf.ivinitted)) { 100 get_random_bytes(esp->conf.ivec, esp->conf.ivlen); 101 esp->conf.ivinitted = 1; 102 } 103 crypto_blkcipher_set_iv(tfm, esp->conf.ivec, esp->conf.ivlen); 104 } 105 106 do { 107 struct scatterlist *sg = &esp->sgbuf[0]; 108 109 if (unlikely(nfrags > ESP_NUM_FAST_SG)) { 110 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); 111 if (!sg) 112 goto unlock; 113 } 114 sg_init_table(sg, nfrags); 115 skb_to_sgvec(skb, sg, 116 esph->enc_data + 117 esp->conf.ivlen - 118 skb->data, clen); 119 err = crypto_blkcipher_encrypt(&desc, sg, sg, clen); 120 if (unlikely(sg != &esp->sgbuf[0])) 121 kfree(sg); 122 } while (0); 123 124 if (unlikely(err)) 125 goto unlock; 126 127 if (esp->conf.ivlen) { 128 memcpy(esph->enc_data, esp->conf.ivec, esp->conf.ivlen); 129 crypto_blkcipher_get_iv(tfm, esp->conf.ivec, esp->conf.ivlen); 130 } 131 132 if (esp->auth.icv_full_len) { 133 err = esp_mac_digest(esp, skb, (u8 *)esph - skb->data, 134 sizeof(*esph) + esp->conf.ivlen + clen); 135 memcpy(pskb_put(skb, trailer, alen), esp->auth.work_icv, alen); 136 } 137 138 unlock: 139 spin_unlock_bh(&x->lock); 140 141 error: 142 return err; 143 } 144 145 /* 146 * Note: detecting truncated vs. non-truncated authentication data is very 147 * expensive, so we only support truncated data, which is the recommended 148 * and common case. 149 */ 150 static int esp_input(struct xfrm_state *x, struct sk_buff *skb) 151 { 152 struct iphdr *iph; 153 struct ip_esp_hdr *esph; 154 struct esp_data *esp = x->data; 155 struct crypto_blkcipher *tfm = esp->conf.tfm; 156 struct blkcipher_desc desc = { .tfm = tfm }; 157 struct sk_buff *trailer; 158 int blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4); 159 int alen = esp->auth.icv_trunc_len; 160 int elen = skb->len - sizeof(*esph) - esp->conf.ivlen - alen; 161 int nfrags; 162 int ihl; 163 u8 nexthdr[2]; 164 struct scatterlist *sg; 165 int padlen; 166 int err; 167 168 if (!pskb_may_pull(skb, sizeof(*esph))) 169 goto out; 170 171 if (elen <= 0 || (elen & (blksize-1))) 172 goto out; 173 174 /* If integrity check is required, do this. */ 175 if (esp->auth.icv_full_len) { 176 u8 sum[alen]; 177 178 err = esp_mac_digest(esp, skb, 0, skb->len - alen); 179 if (err) 180 goto out; 181 182 if (skb_copy_bits(skb, skb->len - alen, sum, alen)) 183 BUG(); 184 185 if (unlikely(memcmp(esp->auth.work_icv, sum, alen))) { 186 x->stats.integrity_failed++; 187 goto out; 188 } 189 } 190 191 if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) 192 goto out; 193 194 skb->ip_summed = CHECKSUM_NONE; 195 196 esph = (struct ip_esp_hdr *)skb->data; 197 198 /* Get ivec. This can be wrong, check against another impls. */ 199 if (esp->conf.ivlen) 200 crypto_blkcipher_set_iv(tfm, esph->enc_data, esp->conf.ivlen); 201 202 sg = &esp->sgbuf[0]; 203 204 if (unlikely(nfrags > ESP_NUM_FAST_SG)) { 205 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); 206 if (!sg) 207 goto out; 208 } 209 sg_init_table(sg, nfrags); 210 skb_to_sgvec(skb, sg, 211 sizeof(*esph) + esp->conf.ivlen, 212 elen); 213 err = crypto_blkcipher_decrypt(&desc, sg, sg, elen); 214 if (unlikely(sg != &esp->sgbuf[0])) 215 kfree(sg); 216 if (unlikely(err)) 217 return err; 218 219 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2)) 220 BUG(); 221 222 padlen = nexthdr[0]; 223 if (padlen+2 >= elen) 224 goto out; 225 226 /* ... check padding bits here. Silly. :-) */ 227 228 /* RFC4303: Drop dummy packets without any error */ 229 if (nexthdr[1] == IPPROTO_NONE) 230 goto out; 231 232 iph = ip_hdr(skb); 233 ihl = iph->ihl * 4; 234 235 if (x->encap) { 236 struct xfrm_encap_tmpl *encap = x->encap; 237 struct udphdr *uh = (void *)(skb_network_header(skb) + ihl); 238 239 /* 240 * 1) if the NAT-T peer's IP or port changed then 241 * advertize the change to the keying daemon. 242 * This is an inbound SA, so just compare 243 * SRC ports. 244 */ 245 if (iph->saddr != x->props.saddr.a4 || 246 uh->source != encap->encap_sport) { 247 xfrm_address_t ipaddr; 248 249 ipaddr.a4 = iph->saddr; 250 km_new_mapping(x, &ipaddr, uh->source); 251 252 /* XXX: perhaps add an extra 253 * policy check here, to see 254 * if we should allow or 255 * reject a packet from a 256 * different source 257 * address/port. 258 */ 259 } 260 261 /* 262 * 2) ignore UDP/TCP checksums in case 263 * of NAT-T in Transport Mode, or 264 * perform other post-processing fixes 265 * as per draft-ietf-ipsec-udp-encaps-06, 266 * section 3.1.2 267 */ 268 if (x->props.mode == XFRM_MODE_TRANSPORT) 269 skb->ip_summed = CHECKSUM_UNNECESSARY; 270 } 271 272 pskb_trim(skb, skb->len - alen - padlen - 2); 273 __skb_pull(skb, sizeof(*esph) + esp->conf.ivlen); 274 skb_set_transport_header(skb, -ihl); 275 276 return nexthdr[1]; 277 278 out: 279 return -EINVAL; 280 } 281 282 static u32 esp4_get_mtu(struct xfrm_state *x, int mtu) 283 { 284 struct esp_data *esp = x->data; 285 u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4); 286 u32 align = max_t(u32, blksize, esp->conf.padlen); 287 u32 rem; 288 289 mtu -= x->props.header_len + esp->auth.icv_trunc_len; 290 rem = mtu & (align - 1); 291 mtu &= ~(align - 1); 292 293 switch (x->props.mode) { 294 case XFRM_MODE_TUNNEL: 295 break; 296 default: 297 case XFRM_MODE_TRANSPORT: 298 /* The worst case */ 299 mtu -= blksize - 4; 300 mtu += min_t(u32, blksize - 4, rem); 301 break; 302 case XFRM_MODE_BEET: 303 /* The worst case. */ 304 mtu += min_t(u32, IPV4_BEET_PHMAXLEN, rem); 305 break; 306 } 307 308 return mtu - 2; 309 } 310 311 static void esp4_err(struct sk_buff *skb, u32 info) 312 { 313 struct iphdr *iph = (struct iphdr*)skb->data; 314 struct ip_esp_hdr *esph = (struct ip_esp_hdr*)(skb->data+(iph->ihl<<2)); 315 struct xfrm_state *x; 316 317 if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH || 318 icmp_hdr(skb)->code != ICMP_FRAG_NEEDED) 319 return; 320 321 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET); 322 if (!x) 323 return; 324 NETDEBUG(KERN_DEBUG "pmtu discovery on SA ESP/%08x/%08x\n", 325 ntohl(esph->spi), ntohl(iph->daddr)); 326 xfrm_state_put(x); 327 } 328 329 static void esp_destroy(struct xfrm_state *x) 330 { 331 struct esp_data *esp = x->data; 332 333 if (!esp) 334 return; 335 336 crypto_free_blkcipher(esp->conf.tfm); 337 esp->conf.tfm = NULL; 338 kfree(esp->conf.ivec); 339 esp->conf.ivec = NULL; 340 crypto_free_hash(esp->auth.tfm); 341 esp->auth.tfm = NULL; 342 kfree(esp->auth.work_icv); 343 esp->auth.work_icv = NULL; 344 kfree(esp); 345 } 346 347 static int esp_init_state(struct xfrm_state *x) 348 { 349 struct esp_data *esp = NULL; 350 struct crypto_blkcipher *tfm; 351 u32 align; 352 353 if (x->ealg == NULL) 354 goto error; 355 356 esp = kzalloc(sizeof(*esp), GFP_KERNEL); 357 if (esp == NULL) 358 return -ENOMEM; 359 360 if (x->aalg) { 361 struct xfrm_algo_desc *aalg_desc; 362 struct crypto_hash *hash; 363 364 hash = crypto_alloc_hash(x->aalg->alg_name, 0, 365 CRYPTO_ALG_ASYNC); 366 if (IS_ERR(hash)) 367 goto error; 368 369 esp->auth.tfm = hash; 370 if (crypto_hash_setkey(hash, x->aalg->alg_key, 371 (x->aalg->alg_key_len + 7) / 8)) 372 goto error; 373 374 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 375 BUG_ON(!aalg_desc); 376 377 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 378 crypto_hash_digestsize(hash)) { 379 NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n", 380 x->aalg->alg_name, 381 crypto_hash_digestsize(hash), 382 aalg_desc->uinfo.auth.icv_fullbits/8); 383 goto error; 384 } 385 386 esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; 387 esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8; 388 389 esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL); 390 if (!esp->auth.work_icv) 391 goto error; 392 } 393 394 tfm = crypto_alloc_blkcipher(x->ealg->alg_name, 0, CRYPTO_ALG_ASYNC); 395 if (IS_ERR(tfm)) 396 goto error; 397 esp->conf.tfm = tfm; 398 esp->conf.ivlen = crypto_blkcipher_ivsize(tfm); 399 esp->conf.padlen = 0; 400 if (esp->conf.ivlen) { 401 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL); 402 if (unlikely(esp->conf.ivec == NULL)) 403 goto error; 404 esp->conf.ivinitted = 0; 405 } 406 if (crypto_blkcipher_setkey(tfm, x->ealg->alg_key, 407 (x->ealg->alg_key_len + 7) / 8)) 408 goto error; 409 x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen; 410 if (x->props.mode == XFRM_MODE_TUNNEL) 411 x->props.header_len += sizeof(struct iphdr); 412 else if (x->props.mode == XFRM_MODE_BEET) 413 x->props.header_len += IPV4_BEET_PHMAXLEN; 414 if (x->encap) { 415 struct xfrm_encap_tmpl *encap = x->encap; 416 417 switch (encap->encap_type) { 418 default: 419 goto error; 420 case UDP_ENCAP_ESPINUDP: 421 x->props.header_len += sizeof(struct udphdr); 422 break; 423 case UDP_ENCAP_ESPINUDP_NON_IKE: 424 x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32); 425 break; 426 } 427 } 428 x->data = esp; 429 align = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4); 430 if (esp->conf.padlen) 431 align = max_t(u32, align, esp->conf.padlen); 432 x->props.trailer_len = align + 1 + esp->auth.icv_trunc_len; 433 return 0; 434 435 error: 436 x->data = esp; 437 esp_destroy(x); 438 x->data = NULL; 439 return -EINVAL; 440 } 441 442 static struct xfrm_type esp_type = 443 { 444 .description = "ESP4", 445 .owner = THIS_MODULE, 446 .proto = IPPROTO_ESP, 447 .flags = XFRM_TYPE_REPLAY_PROT, 448 .init_state = esp_init_state, 449 .destructor = esp_destroy, 450 .get_mtu = esp4_get_mtu, 451 .input = esp_input, 452 .output = esp_output 453 }; 454 455 static struct net_protocol esp4_protocol = { 456 .handler = xfrm4_rcv, 457 .err_handler = esp4_err, 458 .no_policy = 1, 459 }; 460 461 static int __init esp4_init(void) 462 { 463 if (xfrm_register_type(&esp_type, AF_INET) < 0) { 464 printk(KERN_INFO "ip esp init: can't add xfrm type\n"); 465 return -EAGAIN; 466 } 467 if (inet_add_protocol(&esp4_protocol, IPPROTO_ESP) < 0) { 468 printk(KERN_INFO "ip esp init: can't add protocol\n"); 469 xfrm_unregister_type(&esp_type, AF_INET); 470 return -EAGAIN; 471 } 472 return 0; 473 } 474 475 static void __exit esp4_fini(void) 476 { 477 if (inet_del_protocol(&esp4_protocol, IPPROTO_ESP) < 0) 478 printk(KERN_INFO "ip esp close: can't remove protocol\n"); 479 if (xfrm_unregister_type(&esp_type, AF_INET) < 0) 480 printk(KERN_INFO "ip esp close: can't remove xfrm type\n"); 481 } 482 483 module_init(esp4_init); 484 module_exit(esp4_fini); 485 MODULE_LICENSE("GPL"); 486 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_ESP); 487