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 int blksize; 25 int clen; 26 int alen; 27 int nfrags; 28 29 /* Strip IP+ESP header. */ 30 __skb_pull(skb, skb->h.raw - skb->data); 31 /* Now 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 do { 53 int i; 54 for (i=0; i<clen-skb->len - 2; i++) 55 *(u8*)(trailer->tail + i) = i+1; 56 } while (0); 57 *(u8*)(trailer->tail + clen-skb->len - 2) = (clen - skb->len)-2; 58 pskb_put(skb, trailer, clen - skb->len); 59 60 __skb_push(skb, skb->data - skb->nh.raw); 61 top_iph = skb->nh.iph; 62 esph = (struct ip_esp_hdr *)(skb->nh.raw + top_iph->ihl*4); 63 top_iph->tot_len = htons(skb->len + alen); 64 *(u8*)(trailer->tail - 1) = top_iph->protocol; 65 66 /* this is non-NULL only with UDP Encapsulation */ 67 if (x->encap) { 68 struct xfrm_encap_tmpl *encap = x->encap; 69 struct udphdr *uh; 70 __be32 *udpdata32; 71 72 uh = (struct udphdr *)esph; 73 uh->source = encap->encap_sport; 74 uh->dest = encap->encap_dport; 75 uh->len = htons(skb->len + alen - top_iph->ihl*4); 76 uh->check = 0; 77 78 switch (encap->encap_type) { 79 default: 80 case UDP_ENCAP_ESPINUDP: 81 esph = (struct ip_esp_hdr *)(uh + 1); 82 break; 83 case UDP_ENCAP_ESPINUDP_NON_IKE: 84 udpdata32 = (__be32 *)(uh + 1); 85 udpdata32[0] = udpdata32[1] = 0; 86 esph = (struct ip_esp_hdr *)(udpdata32 + 2); 87 break; 88 } 89 90 top_iph->protocol = IPPROTO_UDP; 91 } else 92 top_iph->protocol = IPPROTO_ESP; 93 94 esph->spi = x->id.spi; 95 esph->seq_no = htonl(++x->replay.oseq); 96 xfrm_aevent_doreplay(x); 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 error; 113 } 114 skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen); 115 err = crypto_blkcipher_encrypt(&desc, sg, sg, clen); 116 if (unlikely(sg != &esp->sgbuf[0])) 117 kfree(sg); 118 } while (0); 119 120 if (unlikely(err)) 121 goto error; 122 123 if (esp->conf.ivlen) { 124 memcpy(esph->enc_data, esp->conf.ivec, esp->conf.ivlen); 125 crypto_blkcipher_get_iv(tfm, esp->conf.ivec, esp->conf.ivlen); 126 } 127 128 if (esp->auth.icv_full_len) { 129 err = esp_mac_digest(esp, skb, (u8 *)esph - skb->data, 130 sizeof(*esph) + esp->conf.ivlen + clen); 131 memcpy(pskb_put(skb, trailer, alen), esp->auth.work_icv, alen); 132 } 133 134 ip_send_check(top_iph); 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(struct ip_esp_hdr) - 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(struct ip_esp_hdr))) 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(struct ip_esp_hdr) + 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 = skb->nh.iph; 221 ihl = iph->ihl * 4; 222 223 if (x->encap) { 224 struct xfrm_encap_tmpl *encap = x->encap; 225 struct udphdr *uh = (void *)(skb->nh.raw + 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 x->props.mode == XFRM_MODE_BEET) 258 skb->ip_summed = CHECKSUM_UNNECESSARY; 259 } 260 261 iph->protocol = nexthdr[1]; 262 pskb_trim(skb, skb->len - alen - padlen - 2); 263 skb->h.raw = __skb_pull(skb, sizeof(*esph) + esp->conf.ivlen) - ihl; 264 265 return 0; 266 267 out: 268 return -EINVAL; 269 } 270 271 static u32 esp4_get_max_size(struct xfrm_state *x, int mtu) 272 { 273 struct esp_data *esp = x->data; 274 u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4); 275 int enclen = 0; 276 277 switch (x->props.mode) { 278 case XFRM_MODE_TUNNEL: 279 mtu = ALIGN(mtu +2, blksize); 280 break; 281 default: 282 case XFRM_MODE_TRANSPORT: 283 /* The worst case */ 284 mtu = ALIGN(mtu + 2, 4) + blksize - 4; 285 break; 286 case XFRM_MODE_BEET: 287 /* The worst case. */ 288 enclen = IPV4_BEET_PHMAXLEN; 289 mtu = ALIGN(mtu + enclen + 2, blksize); 290 break; 291 } 292 293 if (esp->conf.padlen) 294 mtu = ALIGN(mtu, esp->conf.padlen); 295 296 return mtu + x->props.header_len + esp->auth.icv_trunc_len - enclen; 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 (skb->h.icmph->type != ICMP_DEST_UNREACH || 306 skb->h.icmph->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; 339 340 /* null auth and encryption can have zero length keys */ 341 if (x->aalg) { 342 if (x->aalg->alg_key_len > 512) 343 goto error; 344 } 345 if (x->ealg == NULL) 346 goto error; 347 348 esp = kzalloc(sizeof(*esp), GFP_KERNEL); 349 if (esp == NULL) 350 return -ENOMEM; 351 352 if (x->aalg) { 353 struct xfrm_algo_desc *aalg_desc; 354 struct crypto_hash *hash; 355 356 esp->auth.key = x->aalg->alg_key; 357 esp->auth.key_len = (x->aalg->alg_key_len+7)/8; 358 hash = crypto_alloc_hash(x->aalg->alg_name, 0, 359 CRYPTO_ALG_ASYNC); 360 if (IS_ERR(hash)) 361 goto error; 362 363 esp->auth.tfm = hash; 364 if (crypto_hash_setkey(hash, esp->auth.key, esp->auth.key_len)) 365 goto error; 366 367 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 368 BUG_ON(!aalg_desc); 369 370 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 371 crypto_hash_digestsize(hash)) { 372 NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n", 373 x->aalg->alg_name, 374 crypto_hash_digestsize(hash), 375 aalg_desc->uinfo.auth.icv_fullbits/8); 376 goto error; 377 } 378 379 esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; 380 esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8; 381 382 esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL); 383 if (!esp->auth.work_icv) 384 goto error; 385 } 386 esp->conf.key = x->ealg->alg_key; 387 esp->conf.key_len = (x->ealg->alg_key_len+7)/8; 388 tfm = crypto_alloc_blkcipher(x->ealg->alg_name, 0, CRYPTO_ALG_ASYNC); 389 if (IS_ERR(tfm)) 390 goto error; 391 esp->conf.tfm = tfm; 392 esp->conf.ivlen = crypto_blkcipher_ivsize(tfm); 393 esp->conf.padlen = 0; 394 if (esp->conf.ivlen) { 395 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL); 396 if (unlikely(esp->conf.ivec == NULL)) 397 goto error; 398 esp->conf.ivinitted = 0; 399 } 400 if (crypto_blkcipher_setkey(tfm, esp->conf.key, esp->conf.key_len)) 401 goto error; 402 x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen; 403 if (x->props.mode == XFRM_MODE_TUNNEL) 404 x->props.header_len += sizeof(struct iphdr); 405 if (x->encap) { 406 struct xfrm_encap_tmpl *encap = x->encap; 407 408 switch (encap->encap_type) { 409 default: 410 goto error; 411 case UDP_ENCAP_ESPINUDP: 412 x->props.header_len += sizeof(struct udphdr); 413 break; 414 case UDP_ENCAP_ESPINUDP_NON_IKE: 415 x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32); 416 break; 417 } 418 } 419 x->data = esp; 420 x->props.trailer_len = esp4_get_max_size(x, 0) - x->props.header_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 .init_state = esp_init_state, 436 .destructor = esp_destroy, 437 .get_max_size = esp4_get_max_size, 438 .input = esp_input, 439 .output = esp_output 440 }; 441 442 static struct net_protocol esp4_protocol = { 443 .handler = xfrm4_rcv, 444 .err_handler = esp4_err, 445 .no_policy = 1, 446 }; 447 448 static int __init esp4_init(void) 449 { 450 if (xfrm_register_type(&esp_type, AF_INET) < 0) { 451 printk(KERN_INFO "ip esp init: can't add xfrm type\n"); 452 return -EAGAIN; 453 } 454 if (inet_add_protocol(&esp4_protocol, IPPROTO_ESP) < 0) { 455 printk(KERN_INFO "ip esp init: can't add protocol\n"); 456 xfrm_unregister_type(&esp_type, AF_INET); 457 return -EAGAIN; 458 } 459 return 0; 460 } 461 462 static void __exit esp4_fini(void) 463 { 464 if (inet_del_protocol(&esp4_protocol, IPPROTO_ESP) < 0) 465 printk(KERN_INFO "ip esp close: can't remove protocol\n"); 466 if (xfrm_unregister_type(&esp_type, AF_INET) < 0) 467 printk(KERN_INFO "ip esp close: can't remove xfrm type\n"); 468 } 469 470 module_init(esp4_init); 471 module_exit(esp4_fini); 472 MODULE_LICENSE("GPL"); 473