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