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 <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 skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen); 114 err = crypto_blkcipher_encrypt(&desc, sg, sg, clen); 115 if (unlikely(sg != &esp->sgbuf[0])) 116 kfree(sg); 117 } while (0); 118 119 if (unlikely(err)) 120 goto unlock; 121 122 if (esp->conf.ivlen) { 123 memcpy(esph->enc_data, esp->conf.ivec, esp->conf.ivlen); 124 crypto_blkcipher_get_iv(tfm, esp->conf.ivec, esp->conf.ivlen); 125 } 126 127 if (esp->auth.icv_full_len) { 128 err = esp_mac_digest(esp, skb, (u8 *)esph - skb->data, 129 sizeof(*esph) + esp->conf.ivlen + clen); 130 memcpy(pskb_put(skb, trailer, alen), esp->auth.work_icv, alen); 131 } 132 133 unlock: 134 spin_unlock_bh(&x->lock); 135 136 error: 137 return err; 138 } 139 140 /* 141 * Note: detecting truncated vs. non-truncated authentication data is very 142 * expensive, so we only support truncated data, which is the recommended 143 * and common case. 144 */ 145 static int esp_input(struct xfrm_state *x, struct sk_buff *skb) 146 { 147 struct iphdr *iph; 148 struct ip_esp_hdr *esph; 149 struct esp_data *esp = x->data; 150 struct crypto_blkcipher *tfm = esp->conf.tfm; 151 struct blkcipher_desc desc = { .tfm = tfm }; 152 struct sk_buff *trailer; 153 int blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4); 154 int alen = esp->auth.icv_trunc_len; 155 int elen = skb->len - sizeof(*esph) - esp->conf.ivlen - alen; 156 int nfrags; 157 int ihl; 158 u8 nexthdr[2]; 159 struct scatterlist *sg; 160 int padlen; 161 int err; 162 163 if (!pskb_may_pull(skb, sizeof(*esph))) 164 goto out; 165 166 if (elen <= 0 || (elen & (blksize-1))) 167 goto out; 168 169 /* If integrity check is required, do this. */ 170 if (esp->auth.icv_full_len) { 171 u8 sum[alen]; 172 173 err = esp_mac_digest(esp, skb, 0, skb->len - alen); 174 if (err) 175 goto out; 176 177 if (skb_copy_bits(skb, skb->len - alen, sum, alen)) 178 BUG(); 179 180 if (unlikely(memcmp(esp->auth.work_icv, sum, alen))) { 181 x->stats.integrity_failed++; 182 goto out; 183 } 184 } 185 186 if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) 187 goto out; 188 189 skb->ip_summed = CHECKSUM_NONE; 190 191 esph = (struct ip_esp_hdr *)skb->data; 192 193 /* Get ivec. This can be wrong, check against another impls. */ 194 if (esp->conf.ivlen) 195 crypto_blkcipher_set_iv(tfm, esph->enc_data, esp->conf.ivlen); 196 197 sg = &esp->sgbuf[0]; 198 199 if (unlikely(nfrags > ESP_NUM_FAST_SG)) { 200 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); 201 if (!sg) 202 goto out; 203 } 204 skb_to_sgvec(skb, sg, sizeof(*esph) + esp->conf.ivlen, elen); 205 err = crypto_blkcipher_decrypt(&desc, sg, sg, elen); 206 if (unlikely(sg != &esp->sgbuf[0])) 207 kfree(sg); 208 if (unlikely(err)) 209 return err; 210 211 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2)) 212 BUG(); 213 214 padlen = nexthdr[0]; 215 if (padlen+2 >= elen) 216 goto out; 217 218 /* ... check padding bits here. Silly. :-) */ 219 220 iph = ip_hdr(skb); 221 ihl = iph->ihl * 4; 222 223 if (x->encap) { 224 struct xfrm_encap_tmpl *encap = x->encap; 225 struct udphdr *uh = (void *)(skb_network_header(skb) + ihl); 226 227 /* 228 * 1) if the NAT-T peer's IP or port changed then 229 * advertize the change to the keying daemon. 230 * This is an inbound SA, so just compare 231 * SRC ports. 232 */ 233 if (iph->saddr != x->props.saddr.a4 || 234 uh->source != encap->encap_sport) { 235 xfrm_address_t ipaddr; 236 237 ipaddr.a4 = iph->saddr; 238 km_new_mapping(x, &ipaddr, uh->source); 239 240 /* XXX: perhaps add an extra 241 * policy check here, to see 242 * if we should allow or 243 * reject a packet from a 244 * different source 245 * address/port. 246 */ 247 } 248 249 /* 250 * 2) ignore UDP/TCP checksums in case 251 * of NAT-T in Transport Mode, or 252 * perform other post-processing fixes 253 * as per draft-ietf-ipsec-udp-encaps-06, 254 * section 3.1.2 255 */ 256 if (x->props.mode == XFRM_MODE_TRANSPORT) 257 skb->ip_summed = CHECKSUM_UNNECESSARY; 258 } 259 260 pskb_trim(skb, skb->len - alen - padlen - 2); 261 __skb_pull(skb, sizeof(*esph) + esp->conf.ivlen); 262 skb_set_transport_header(skb, -ihl); 263 264 return nexthdr[1]; 265 266 out: 267 return -EINVAL; 268 } 269 270 static u32 esp4_get_mtu(struct xfrm_state *x, int mtu) 271 { 272 struct esp_data *esp = x->data; 273 u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4); 274 u32 align = max_t(u32, blksize, esp->conf.padlen); 275 u32 rem; 276 277 mtu -= x->props.header_len + esp->auth.icv_trunc_len; 278 rem = mtu & (align - 1); 279 mtu &= ~(align - 1); 280 281 switch (x->props.mode) { 282 case XFRM_MODE_TUNNEL: 283 break; 284 default: 285 case XFRM_MODE_TRANSPORT: 286 /* The worst case */ 287 mtu -= blksize - 4; 288 mtu += min_t(u32, blksize - 4, rem); 289 break; 290 case XFRM_MODE_BEET: 291 /* The worst case. */ 292 mtu += min_t(u32, IPV4_BEET_PHMAXLEN, rem); 293 break; 294 } 295 296 return mtu - 2; 297 } 298 299 static void esp4_err(struct sk_buff *skb, u32 info) 300 { 301 struct iphdr *iph = (struct iphdr*)skb->data; 302 struct ip_esp_hdr *esph = (struct ip_esp_hdr*)(skb->data+(iph->ihl<<2)); 303 struct xfrm_state *x; 304 305 if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH || 306 icmp_hdr(skb)->code != ICMP_FRAG_NEEDED) 307 return; 308 309 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET); 310 if (!x) 311 return; 312 NETDEBUG(KERN_DEBUG "pmtu discovery on SA ESP/%08x/%08x\n", 313 ntohl(esph->spi), ntohl(iph->daddr)); 314 xfrm_state_put(x); 315 } 316 317 static void esp_destroy(struct xfrm_state *x) 318 { 319 struct esp_data *esp = x->data; 320 321 if (!esp) 322 return; 323 324 crypto_free_blkcipher(esp->conf.tfm); 325 esp->conf.tfm = NULL; 326 kfree(esp->conf.ivec); 327 esp->conf.ivec = NULL; 328 crypto_free_hash(esp->auth.tfm); 329 esp->auth.tfm = NULL; 330 kfree(esp->auth.work_icv); 331 esp->auth.work_icv = NULL; 332 kfree(esp); 333 } 334 335 static int esp_init_state(struct xfrm_state *x) 336 { 337 struct esp_data *esp = NULL; 338 struct crypto_blkcipher *tfm; 339 u32 align; 340 341 if (x->ealg == NULL) 342 goto error; 343 344 esp = kzalloc(sizeof(*esp), GFP_KERNEL); 345 if (esp == NULL) 346 return -ENOMEM; 347 348 if (x->aalg) { 349 struct xfrm_algo_desc *aalg_desc; 350 struct crypto_hash *hash; 351 352 hash = crypto_alloc_hash(x->aalg->alg_name, 0, 353 CRYPTO_ALG_ASYNC); 354 if (IS_ERR(hash)) 355 goto error; 356 357 esp->auth.tfm = hash; 358 if (crypto_hash_setkey(hash, x->aalg->alg_key, 359 (x->aalg->alg_key_len + 7) / 8)) 360 goto error; 361 362 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 363 BUG_ON(!aalg_desc); 364 365 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 366 crypto_hash_digestsize(hash)) { 367 NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n", 368 x->aalg->alg_name, 369 crypto_hash_digestsize(hash), 370 aalg_desc->uinfo.auth.icv_fullbits/8); 371 goto error; 372 } 373 374 esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; 375 esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8; 376 377 esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL); 378 if (!esp->auth.work_icv) 379 goto error; 380 } 381 382 tfm = crypto_alloc_blkcipher(x->ealg->alg_name, 0, CRYPTO_ALG_ASYNC); 383 if (IS_ERR(tfm)) 384 goto error; 385 esp->conf.tfm = tfm; 386 esp->conf.ivlen = crypto_blkcipher_ivsize(tfm); 387 esp->conf.padlen = 0; 388 if (esp->conf.ivlen) { 389 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL); 390 if (unlikely(esp->conf.ivec == NULL)) 391 goto error; 392 esp->conf.ivinitted = 0; 393 } 394 if (crypto_blkcipher_setkey(tfm, x->ealg->alg_key, 395 (x->ealg->alg_key_len + 7) / 8)) 396 goto error; 397 x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen; 398 if (x->props.mode == XFRM_MODE_TUNNEL) 399 x->props.header_len += sizeof(struct iphdr); 400 else if (x->props.mode == XFRM_MODE_BEET) 401 x->props.header_len += IPV4_BEET_PHMAXLEN; 402 if (x->encap) { 403 struct xfrm_encap_tmpl *encap = x->encap; 404 405 switch (encap->encap_type) { 406 default: 407 goto error; 408 case UDP_ENCAP_ESPINUDP: 409 x->props.header_len += sizeof(struct udphdr); 410 break; 411 case UDP_ENCAP_ESPINUDP_NON_IKE: 412 x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32); 413 break; 414 } 415 } 416 x->data = esp; 417 align = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4); 418 if (esp->conf.padlen) 419 align = max_t(u32, align, esp->conf.padlen); 420 x->props.trailer_len = align + 1 + esp->auth.icv_trunc_len; 421 return 0; 422 423 error: 424 x->data = esp; 425 esp_destroy(x); 426 x->data = NULL; 427 return -EINVAL; 428 } 429 430 static struct xfrm_type esp_type = 431 { 432 .description = "ESP4", 433 .owner = THIS_MODULE, 434 .proto = IPPROTO_ESP, 435 .flags = XFRM_TYPE_REPLAY_PROT, 436 .init_state = esp_init_state, 437 .destructor = esp_destroy, 438 .get_mtu = esp4_get_mtu, 439 .input = esp_input, 440 .output = esp_output 441 }; 442 443 static struct net_protocol esp4_protocol = { 444 .handler = xfrm4_rcv, 445 .err_handler = esp4_err, 446 .no_policy = 1, 447 }; 448 449 static int __init esp4_init(void) 450 { 451 if (xfrm_register_type(&esp_type, AF_INET) < 0) { 452 printk(KERN_INFO "ip esp init: can't add xfrm type\n"); 453 return -EAGAIN; 454 } 455 if (inet_add_protocol(&esp4_protocol, IPPROTO_ESP) < 0) { 456 printk(KERN_INFO "ip esp init: can't add protocol\n"); 457 xfrm_unregister_type(&esp_type, AF_INET); 458 return -EAGAIN; 459 } 460 return 0; 461 } 462 463 static void __exit esp4_fini(void) 464 { 465 if (inet_del_protocol(&esp4_protocol, IPPROTO_ESP) < 0) 466 printk(KERN_INFO "ip esp close: can't remove protocol\n"); 467 if (xfrm_unregister_type(&esp_type, AF_INET) < 0) 468 printk(KERN_INFO "ip esp close: can't remove xfrm type\n"); 469 } 470 471 module_init(esp4_init); 472 module_exit(esp4_fini); 473 MODULE_LICENSE("GPL"); 474 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_ESP); 475