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 <asm/scatterlist.h> 7 #include <linux/crypto.h> 8 #include <linux/kernel.h> 9 #include <linux/pfkeyv2.h> 10 #include <linux/random.h> 11 #include <net/icmp.h> 12 #include <net/protocol.h> 13 #include <net/udp.h> 14 15 static int esp_output(struct xfrm_state *x, struct sk_buff *skb) 16 { 17 int err; 18 struct iphdr *top_iph; 19 struct ip_esp_hdr *esph; 20 struct crypto_blkcipher *tfm; 21 struct blkcipher_desc desc; 22 struct esp_data *esp; 23 struct sk_buff *trailer; 24 u8 *tail; 25 int blksize; 26 int clen; 27 int alen; 28 int nfrags; 29 30 /* Strip IP+ESP header. */ 31 __skb_pull(skb, skb_transport_offset(skb)); 32 /* Now skb is pure payload to encrypt */ 33 34 err = -ENOMEM; 35 36 /* Round to block size */ 37 clen = skb->len; 38 39 esp = x->data; 40 alen = esp->auth.icv_trunc_len; 41 tfm = esp->conf.tfm; 42 desc.tfm = tfm; 43 desc.flags = 0; 44 blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4); 45 clen = ALIGN(clen + 2, blksize); 46 if (esp->conf.padlen) 47 clen = ALIGN(clen, esp->conf.padlen); 48 49 if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0) 50 goto error; 51 52 /* Fill padding... */ 53 tail = skb_tail_pointer(trailer); 54 do { 55 int i; 56 for (i=0; i<clen-skb->len - 2; i++) 57 tail[i] = i + 1; 58 } while (0); 59 tail[clen - skb->len - 2] = (clen - skb->len) - 2; 60 pskb_put(skb, trailer, clen - skb->len); 61 62 __skb_push(skb, skb->data - skb_network_header(skb)); 63 top_iph = ip_hdr(skb); 64 esph = (struct ip_esp_hdr *)(skb_network_header(skb) + 65 top_iph->ihl * 4); 66 top_iph->tot_len = htons(skb->len + alen); 67 *(skb_tail_pointer(trailer) - 1) = top_iph->protocol; 68 69 /* this is non-NULL only with UDP Encapsulation */ 70 if (x->encap) { 71 struct xfrm_encap_tmpl *encap = x->encap; 72 struct udphdr *uh; 73 __be32 *udpdata32; 74 75 uh = (struct udphdr *)esph; 76 uh->source = encap->encap_sport; 77 uh->dest = encap->encap_dport; 78 uh->len = htons(skb->len + alen - top_iph->ihl*4); 79 uh->check = 0; 80 81 switch (encap->encap_type) { 82 default: 83 case UDP_ENCAP_ESPINUDP: 84 esph = (struct ip_esp_hdr *)(uh + 1); 85 break; 86 case UDP_ENCAP_ESPINUDP_NON_IKE: 87 udpdata32 = (__be32 *)(uh + 1); 88 udpdata32[0] = udpdata32[1] = 0; 89 esph = (struct ip_esp_hdr *)(udpdata32 + 2); 90 break; 91 } 92 93 top_iph->protocol = IPPROTO_UDP; 94 } else 95 top_iph->protocol = IPPROTO_ESP; 96 97 esph->spi = x->id.spi; 98 esph->seq_no = htonl(++x->replay.oseq); 99 xfrm_aevent_doreplay(x); 100 101 if (esp->conf.ivlen) { 102 if (unlikely(!esp->conf.ivinitted)) { 103 get_random_bytes(esp->conf.ivec, esp->conf.ivlen); 104 esp->conf.ivinitted = 1; 105 } 106 crypto_blkcipher_set_iv(tfm, esp->conf.ivec, esp->conf.ivlen); 107 } 108 109 do { 110 struct scatterlist *sg = &esp->sgbuf[0]; 111 112 if (unlikely(nfrags > ESP_NUM_FAST_SG)) { 113 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); 114 if (!sg) 115 goto error; 116 } 117 skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen); 118 err = crypto_blkcipher_encrypt(&desc, sg, sg, clen); 119 if (unlikely(sg != &esp->sgbuf[0])) 120 kfree(sg); 121 } while (0); 122 123 if (unlikely(err)) 124 goto error; 125 126 if (esp->conf.ivlen) { 127 memcpy(esph->enc_data, esp->conf.ivec, esp->conf.ivlen); 128 crypto_blkcipher_get_iv(tfm, esp->conf.ivec, esp->conf.ivlen); 129 } 130 131 if (esp->auth.icv_full_len) { 132 err = esp_mac_digest(esp, skb, (u8 *)esph - skb->data, 133 sizeof(*esph) + esp->conf.ivlen + clen); 134 memcpy(pskb_put(skb, trailer, alen), esp->auth.work_icv, alen); 135 } 136 137 ip_send_check(top_iph); 138 139 error: 140 return err; 141 } 142 143 /* 144 * Note: detecting truncated vs. non-truncated authentication data is very 145 * expensive, so we only support truncated data, which is the recommended 146 * and common case. 147 */ 148 static int esp_input(struct xfrm_state *x, struct sk_buff *skb) 149 { 150 struct iphdr *iph; 151 struct ip_esp_hdr *esph; 152 struct esp_data *esp = x->data; 153 struct crypto_blkcipher *tfm = esp->conf.tfm; 154 struct blkcipher_desc desc = { .tfm = tfm }; 155 struct sk_buff *trailer; 156 int blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4); 157 int alen = esp->auth.icv_trunc_len; 158 int elen = skb->len - sizeof(struct ip_esp_hdr) - esp->conf.ivlen - alen; 159 int nfrags; 160 int ihl; 161 u8 nexthdr[2]; 162 struct scatterlist *sg; 163 int padlen; 164 int err; 165 166 if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr))) 167 goto out; 168 169 if (elen <= 0 || (elen & (blksize-1))) 170 goto out; 171 172 /* If integrity check is required, do this. */ 173 if (esp->auth.icv_full_len) { 174 u8 sum[alen]; 175 176 err = esp_mac_digest(esp, skb, 0, skb->len - alen); 177 if (err) 178 goto out; 179 180 if (skb_copy_bits(skb, skb->len - alen, sum, alen)) 181 BUG(); 182 183 if (unlikely(memcmp(esp->auth.work_icv, sum, alen))) { 184 x->stats.integrity_failed++; 185 goto out; 186 } 187 } 188 189 if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) 190 goto out; 191 192 skb->ip_summed = CHECKSUM_NONE; 193 194 esph = (struct ip_esp_hdr*)skb->data; 195 196 /* Get ivec. This can be wrong, check against another impls. */ 197 if (esp->conf.ivlen) 198 crypto_blkcipher_set_iv(tfm, esph->enc_data, esp->conf.ivlen); 199 200 sg = &esp->sgbuf[0]; 201 202 if (unlikely(nfrags > ESP_NUM_FAST_SG)) { 203 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); 204 if (!sg) 205 goto out; 206 } 207 skb_to_sgvec(skb, sg, sizeof(struct ip_esp_hdr) + esp->conf.ivlen, elen); 208 err = crypto_blkcipher_decrypt(&desc, sg, sg, elen); 209 if (unlikely(sg != &esp->sgbuf[0])) 210 kfree(sg); 211 if (unlikely(err)) 212 return err; 213 214 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2)) 215 BUG(); 216 217 padlen = nexthdr[0]; 218 if (padlen+2 >= elen) 219 goto out; 220 221 /* ... check padding bits here. Silly. :-) */ 222 223 iph = ip_hdr(skb); 224 ihl = iph->ihl * 4; 225 226 if (x->encap) { 227 struct xfrm_encap_tmpl *encap = x->encap; 228 struct udphdr *uh = (void *)(skb_network_header(skb) + ihl); 229 230 /* 231 * 1) if the NAT-T peer's IP or port changed then 232 * advertize the change to the keying daemon. 233 * This is an inbound SA, so just compare 234 * SRC ports. 235 */ 236 if (iph->saddr != x->props.saddr.a4 || 237 uh->source != encap->encap_sport) { 238 xfrm_address_t ipaddr; 239 240 ipaddr.a4 = iph->saddr; 241 km_new_mapping(x, &ipaddr, uh->source); 242 243 /* XXX: perhaps add an extra 244 * policy check here, to see 245 * if we should allow or 246 * reject a packet from a 247 * different source 248 * address/port. 249 */ 250 } 251 252 /* 253 * 2) ignore UDP/TCP checksums in case 254 * of NAT-T in Transport Mode, or 255 * perform other post-processing fixes 256 * as per draft-ietf-ipsec-udp-encaps-06, 257 * section 3.1.2 258 */ 259 if (x->props.mode == XFRM_MODE_TRANSPORT || 260 x->props.mode == XFRM_MODE_BEET) 261 skb->ip_summed = CHECKSUM_UNNECESSARY; 262 } 263 264 iph->protocol = nexthdr[1]; 265 pskb_trim(skb, skb->len - alen - padlen - 2); 266 __skb_pull(skb, sizeof(*esph) + esp->conf.ivlen); 267 skb_set_transport_header(skb, -ihl); 268 269 return 0; 270 271 out: 272 return -EINVAL; 273 } 274 275 static u32 esp4_get_mtu(struct xfrm_state *x, int mtu) 276 { 277 struct esp_data *esp = x->data; 278 u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4); 279 u32 align = max_t(u32, blksize, esp->conf.padlen); 280 u32 rem; 281 282 mtu -= x->props.header_len + esp->auth.icv_trunc_len; 283 rem = mtu & (align - 1); 284 mtu &= ~(align - 1); 285 286 switch (x->props.mode) { 287 case XFRM_MODE_TUNNEL: 288 break; 289 default: 290 case XFRM_MODE_TRANSPORT: 291 /* The worst case */ 292 mtu -= blksize - 4; 293 mtu += min_t(u32, blksize - 4, rem); 294 break; 295 case XFRM_MODE_BEET: 296 /* The worst case. */ 297 mtu += min_t(u32, IPV4_BEET_PHMAXLEN, rem); 298 break; 299 } 300 301 return mtu - 2; 302 } 303 304 static void esp4_err(struct sk_buff *skb, u32 info) 305 { 306 struct iphdr *iph = (struct iphdr*)skb->data; 307 struct ip_esp_hdr *esph = (struct ip_esp_hdr*)(skb->data+(iph->ihl<<2)); 308 struct xfrm_state *x; 309 310 if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH || 311 icmp_hdr(skb)->code != ICMP_FRAG_NEEDED) 312 return; 313 314 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET); 315 if (!x) 316 return; 317 NETDEBUG(KERN_DEBUG "pmtu discovery on SA ESP/%08x/%08x\n", 318 ntohl(esph->spi), ntohl(iph->daddr)); 319 xfrm_state_put(x); 320 } 321 322 static void esp_destroy(struct xfrm_state *x) 323 { 324 struct esp_data *esp = x->data; 325 326 if (!esp) 327 return; 328 329 crypto_free_blkcipher(esp->conf.tfm); 330 esp->conf.tfm = NULL; 331 kfree(esp->conf.ivec); 332 esp->conf.ivec = NULL; 333 crypto_free_hash(esp->auth.tfm); 334 esp->auth.tfm = NULL; 335 kfree(esp->auth.work_icv); 336 esp->auth.work_icv = NULL; 337 kfree(esp); 338 } 339 340 static int esp_init_state(struct xfrm_state *x) 341 { 342 struct esp_data *esp = NULL; 343 struct crypto_blkcipher *tfm; 344 u32 align; 345 346 /* null auth and encryption can have zero length keys */ 347 if (x->aalg) { 348 if (x->aalg->alg_key_len > 512) 349 goto error; 350 } 351 if (x->ealg == NULL) 352 goto error; 353 354 esp = kzalloc(sizeof(*esp), GFP_KERNEL); 355 if (esp == NULL) 356 return -ENOMEM; 357 358 if (x->aalg) { 359 struct xfrm_algo_desc *aalg_desc; 360 struct crypto_hash *hash; 361 362 esp->auth.key = x->aalg->alg_key; 363 esp->auth.key_len = (x->aalg->alg_key_len+7)/8; 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, esp->auth.key, esp->auth.key_len)) 371 goto error; 372 373 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 374 BUG_ON(!aalg_desc); 375 376 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 377 crypto_hash_digestsize(hash)) { 378 NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n", 379 x->aalg->alg_name, 380 crypto_hash_digestsize(hash), 381 aalg_desc->uinfo.auth.icv_fullbits/8); 382 goto error; 383 } 384 385 esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; 386 esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8; 387 388 esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL); 389 if (!esp->auth.work_icv) 390 goto error; 391 } 392 esp->conf.key = x->ealg->alg_key; 393 esp->conf.key_len = (x->ealg->alg_key_len+7)/8; 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, esp->conf.key, esp->conf.key_len)) 407 goto error; 408 x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen; 409 if (x->props.mode == XFRM_MODE_TUNNEL) 410 x->props.header_len += sizeof(struct iphdr); 411 else if (x->props.mode == XFRM_MODE_BEET) 412 x->props.header_len += IPV4_BEET_PHMAXLEN; 413 if (x->encap) { 414 struct xfrm_encap_tmpl *encap = x->encap; 415 416 switch (encap->encap_type) { 417 default: 418 goto error; 419 case UDP_ENCAP_ESPINUDP: 420 x->props.header_len += sizeof(struct udphdr); 421 break; 422 case UDP_ENCAP_ESPINUDP_NON_IKE: 423 x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32); 424 break; 425 } 426 } 427 x->data = esp; 428 align = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4); 429 if (esp->conf.padlen) 430 align = max_t(u32, align, esp->conf.padlen); 431 x->props.trailer_len = align + 1 + esp->auth.icv_trunc_len; 432 return 0; 433 434 error: 435 x->data = esp; 436 esp_destroy(x); 437 x->data = NULL; 438 return -EINVAL; 439 } 440 441 static struct xfrm_type esp_type = 442 { 443 .description = "ESP4", 444 .owner = THIS_MODULE, 445 .proto = IPPROTO_ESP, 446 .init_state = esp_init_state, 447 .destructor = esp_destroy, 448 .get_mtu = esp4_get_mtu, 449 .input = esp_input, 450 .output = esp_output 451 }; 452 453 static struct net_protocol esp4_protocol = { 454 .handler = xfrm4_rcv, 455 .err_handler = esp4_err, 456 .no_policy = 1, 457 }; 458 459 static int __init esp4_init(void) 460 { 461 if (xfrm_register_type(&esp_type, AF_INET) < 0) { 462 printk(KERN_INFO "ip esp init: can't add xfrm type\n"); 463 return -EAGAIN; 464 } 465 if (inet_add_protocol(&esp4_protocol, IPPROTO_ESP) < 0) { 466 printk(KERN_INFO "ip esp init: can't add protocol\n"); 467 xfrm_unregister_type(&esp_type, AF_INET); 468 return -EAGAIN; 469 } 470 return 0; 471 } 472 473 static void __exit esp4_fini(void) 474 { 475 if (inet_del_protocol(&esp4_protocol, IPPROTO_ESP) < 0) 476 printk(KERN_INFO "ip esp close: can't remove protocol\n"); 477 if (xfrm_unregister_type(&esp_type, AF_INET) < 0) 478 printk(KERN_INFO "ip esp close: can't remove xfrm type\n"); 479 } 480 481 module_init(esp4_init); 482 module_exit(esp4_fini); 483 MODULE_LICENSE("GPL"); 484 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_ESP); 485