1 #include <linux/config.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/pfkeyv2.h> 9 #include <linux/random.h> 10 #include <net/icmp.h> 11 #include <net/udp.h> 12 13 /* decapsulation data for use when post-processing */ 14 struct esp_decap_data { 15 xfrm_address_t saddr; 16 __u16 sport; 17 __u8 proto; 18 }; 19 20 static int esp_output(struct xfrm_state *x, struct sk_buff *skb) 21 { 22 int err; 23 struct iphdr *top_iph; 24 struct ip_esp_hdr *esph; 25 struct crypto_tfm *tfm; 26 struct esp_data *esp; 27 struct sk_buff *trailer; 28 int blksize; 29 int clen; 30 int alen; 31 int nfrags; 32 33 /* Strip IP+ESP header. */ 34 __skb_pull(skb, skb->h.raw - skb->data); 35 /* Now skb is pure payload to encrypt */ 36 37 err = -ENOMEM; 38 39 /* Round to block size */ 40 clen = skb->len; 41 42 esp = x->data; 43 alen = esp->auth.icv_trunc_len; 44 tfm = esp->conf.tfm; 45 blksize = (crypto_tfm_alg_blocksize(tfm) + 3) & ~3; 46 clen = (clen + 2 + blksize-1)&~(blksize-1); 47 if (esp->conf.padlen) 48 clen = (clen + esp->conf.padlen-1)&~(esp->conf.padlen-1); 49 50 if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0) 51 goto error; 52 53 /* Fill padding... */ 54 do { 55 int i; 56 for (i=0; i<clen-skb->len - 2; i++) 57 *(u8*)(trailer->tail + i) = i+1; 58 } while (0); 59 *(u8*)(trailer->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->nh.raw); 63 top_iph = skb->nh.iph; 64 esph = (struct ip_esp_hdr *)(skb->nh.raw + top_iph->ihl*4); 65 top_iph->tot_len = htons(skb->len + alen); 66 *(u8*)(trailer->tail - 1) = top_iph->protocol; 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 u32 *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 - top_iph->ihl*4); 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 = (u32 *)(uh + 1); 87 udpdata32[0] = udpdata32[1] = 0; 88 esph = (struct ip_esp_hdr *)(udpdata32 + 2); 89 break; 90 } 91 92 top_iph->protocol = IPPROTO_UDP; 93 } else 94 top_iph->protocol = IPPROTO_ESP; 95 96 esph->spi = x->id.spi; 97 esph->seq_no = htonl(++x->replay.oseq); 98 99 if (esp->conf.ivlen) 100 crypto_cipher_set_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); 101 102 do { 103 struct scatterlist *sg = &esp->sgbuf[0]; 104 105 if (unlikely(nfrags > ESP_NUM_FAST_SG)) { 106 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); 107 if (!sg) 108 goto error; 109 } 110 skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen); 111 crypto_cipher_encrypt(tfm, sg, sg, clen); 112 if (unlikely(sg != &esp->sgbuf[0])) 113 kfree(sg); 114 } while (0); 115 116 if (esp->conf.ivlen) { 117 memcpy(esph->enc_data, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); 118 crypto_cipher_get_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); 119 } 120 121 if (esp->auth.icv_full_len) { 122 esp->auth.icv(esp, skb, (u8*)esph-skb->data, 123 sizeof(struct ip_esp_hdr) + esp->conf.ivlen+clen, trailer->tail); 124 pskb_put(skb, trailer, alen); 125 } 126 127 ip_send_check(top_iph); 128 129 err = 0; 130 131 error: 132 return err; 133 } 134 135 /* 136 * Note: detecting truncated vs. non-truncated authentication data is very 137 * expensive, so we only support truncated data, which is the recommended 138 * and common case. 139 */ 140 static int esp_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb) 141 { 142 struct iphdr *iph; 143 struct ip_esp_hdr *esph; 144 struct esp_data *esp = x->data; 145 struct sk_buff *trailer; 146 int blksize = crypto_tfm_alg_blocksize(esp->conf.tfm); 147 int alen = esp->auth.icv_trunc_len; 148 int elen = skb->len - sizeof(struct ip_esp_hdr) - esp->conf.ivlen - alen; 149 int nfrags; 150 int encap_len = 0; 151 152 if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr))) 153 goto out; 154 155 if (elen <= 0 || (elen & (blksize-1))) 156 goto out; 157 158 /* If integrity check is required, do this. */ 159 if (esp->auth.icv_full_len) { 160 u8 sum[esp->auth.icv_full_len]; 161 u8 sum1[alen]; 162 163 esp->auth.icv(esp, skb, 0, skb->len-alen, sum); 164 165 if (skb_copy_bits(skb, skb->len-alen, sum1, alen)) 166 BUG(); 167 168 if (unlikely(memcmp(sum, sum1, alen))) { 169 x->stats.integrity_failed++; 170 goto out; 171 } 172 } 173 174 if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) 175 goto out; 176 177 skb->ip_summed = CHECKSUM_NONE; 178 179 esph = (struct ip_esp_hdr*)skb->data; 180 iph = skb->nh.iph; 181 182 /* Get ivec. This can be wrong, check against another impls. */ 183 if (esp->conf.ivlen) 184 crypto_cipher_set_iv(esp->conf.tfm, esph->enc_data, crypto_tfm_alg_ivsize(esp->conf.tfm)); 185 186 { 187 u8 nexthdr[2]; 188 struct scatterlist *sg = &esp->sgbuf[0]; 189 u8 workbuf[60]; 190 int padlen; 191 192 if (unlikely(nfrags > ESP_NUM_FAST_SG)) { 193 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); 194 if (!sg) 195 goto out; 196 } 197 skb_to_sgvec(skb, sg, sizeof(struct ip_esp_hdr) + esp->conf.ivlen, elen); 198 crypto_cipher_decrypt(esp->conf.tfm, sg, sg, elen); 199 if (unlikely(sg != &esp->sgbuf[0])) 200 kfree(sg); 201 202 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2)) 203 BUG(); 204 205 padlen = nexthdr[0]; 206 if (padlen+2 >= elen) 207 goto out; 208 209 /* ... check padding bits here. Silly. :-) */ 210 211 if (x->encap && decap && decap->decap_type) { 212 struct esp_decap_data *encap_data; 213 struct udphdr *uh = (struct udphdr *) (iph+1); 214 215 encap_data = (struct esp_decap_data *) (decap->decap_data); 216 encap_data->proto = 0; 217 218 switch (decap->decap_type) { 219 case UDP_ENCAP_ESPINUDP: 220 case UDP_ENCAP_ESPINUDP_NON_IKE: 221 encap_data->proto = AF_INET; 222 encap_data->saddr.a4 = iph->saddr; 223 encap_data->sport = uh->source; 224 encap_len = (void*)esph - (void*)uh; 225 break; 226 227 default: 228 goto out; 229 } 230 } 231 232 iph->protocol = nexthdr[1]; 233 pskb_trim(skb, skb->len - alen - padlen - 2); 234 memcpy(workbuf, skb->nh.raw, iph->ihl*4); 235 skb->h.raw = skb_pull(skb, sizeof(struct ip_esp_hdr) + esp->conf.ivlen); 236 skb->nh.raw += encap_len + sizeof(struct ip_esp_hdr) + esp->conf.ivlen; 237 memcpy(skb->nh.raw, workbuf, iph->ihl*4); 238 skb->nh.iph->tot_len = htons(skb->len); 239 } 240 241 return 0; 242 243 out: 244 return -EINVAL; 245 } 246 247 static int esp_post_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb) 248 { 249 250 if (x->encap) { 251 struct xfrm_encap_tmpl *encap; 252 struct esp_decap_data *decap_data; 253 254 encap = x->encap; 255 decap_data = (struct esp_decap_data *)(decap->decap_data); 256 257 /* first, make sure that the decap type == the encap type */ 258 if (encap->encap_type != decap->decap_type) 259 return -EINVAL; 260 261 switch (encap->encap_type) { 262 default: 263 case UDP_ENCAP_ESPINUDP: 264 case UDP_ENCAP_ESPINUDP_NON_IKE: 265 /* 266 * 1) if the NAT-T peer's IP or port changed then 267 * advertize the change to the keying daemon. 268 * This is an inbound SA, so just compare 269 * SRC ports. 270 */ 271 if (decap_data->proto == AF_INET && 272 (decap_data->saddr.a4 != x->props.saddr.a4 || 273 decap_data->sport != encap->encap_sport)) { 274 xfrm_address_t ipaddr; 275 276 ipaddr.a4 = decap_data->saddr.a4; 277 km_new_mapping(x, &ipaddr, decap_data->sport); 278 279 /* XXX: perhaps add an extra 280 * policy check here, to see 281 * if we should allow or 282 * reject a packet from a 283 * different source 284 * address/port. 285 */ 286 } 287 288 /* 289 * 2) ignore UDP/TCP checksums in case 290 * of NAT-T in Transport Mode, or 291 * perform other post-processing fixes 292 * as per * draft-ietf-ipsec-udp-encaps-06, 293 * section 3.1.2 294 */ 295 if (!x->props.mode) 296 skb->ip_summed = CHECKSUM_UNNECESSARY; 297 298 break; 299 } 300 } 301 return 0; 302 } 303 304 static u32 esp4_get_max_size(struct xfrm_state *x, int mtu) 305 { 306 struct esp_data *esp = x->data; 307 u32 blksize = crypto_tfm_alg_blocksize(esp->conf.tfm); 308 309 if (x->props.mode) { 310 mtu = (mtu + 2 + blksize-1)&~(blksize-1); 311 } else { 312 /* The worst case. */ 313 mtu += 2 + blksize; 314 } 315 if (esp->conf.padlen) 316 mtu = (mtu + esp->conf.padlen-1)&~(esp->conf.padlen-1); 317 318 return mtu + x->props.header_len + esp->auth.icv_trunc_len; 319 } 320 321 static void esp4_err(struct sk_buff *skb, u32 info) 322 { 323 struct iphdr *iph = (struct iphdr*)skb->data; 324 struct ip_esp_hdr *esph = (struct ip_esp_hdr*)(skb->data+(iph->ihl<<2)); 325 struct xfrm_state *x; 326 327 if (skb->h.icmph->type != ICMP_DEST_UNREACH || 328 skb->h.icmph->code != ICMP_FRAG_NEEDED) 329 return; 330 331 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET); 332 if (!x) 333 return; 334 NETDEBUG(KERN_DEBUG "pmtu discovery on SA ESP/%08x/%08x\n", 335 ntohl(esph->spi), ntohl(iph->daddr)); 336 xfrm_state_put(x); 337 } 338 339 static void esp_destroy(struct xfrm_state *x) 340 { 341 struct esp_data *esp = x->data; 342 343 if (!esp) 344 return; 345 346 crypto_free_tfm(esp->conf.tfm); 347 esp->conf.tfm = NULL; 348 kfree(esp->conf.ivec); 349 esp->conf.ivec = NULL; 350 crypto_free_tfm(esp->auth.tfm); 351 esp->auth.tfm = NULL; 352 kfree(esp->auth.work_icv); 353 esp->auth.work_icv = NULL; 354 kfree(esp); 355 } 356 357 static int esp_init_state(struct xfrm_state *x) 358 { 359 struct esp_data *esp = NULL; 360 361 /* null auth and encryption can have zero length keys */ 362 if (x->aalg) { 363 if (x->aalg->alg_key_len > 512) 364 goto error; 365 } 366 if (x->ealg == NULL) 367 goto error; 368 369 esp = kmalloc(sizeof(*esp), GFP_KERNEL); 370 if (esp == NULL) 371 return -ENOMEM; 372 373 memset(esp, 0, sizeof(*esp)); 374 375 if (x->aalg) { 376 struct xfrm_algo_desc *aalg_desc; 377 378 esp->auth.key = x->aalg->alg_key; 379 esp->auth.key_len = (x->aalg->alg_key_len+7)/8; 380 esp->auth.tfm = crypto_alloc_tfm(x->aalg->alg_name, 0); 381 if (esp->auth.tfm == NULL) 382 goto error; 383 esp->auth.icv = esp_hmac_digest; 384 385 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 386 BUG_ON(!aalg_desc); 387 388 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 389 crypto_tfm_alg_digestsize(esp->auth.tfm)) { 390 NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n", 391 x->aalg->alg_name, 392 crypto_tfm_alg_digestsize(esp->auth.tfm), 393 aalg_desc->uinfo.auth.icv_fullbits/8); 394 goto error; 395 } 396 397 esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; 398 esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8; 399 400 esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL); 401 if (!esp->auth.work_icv) 402 goto error; 403 } 404 esp->conf.key = x->ealg->alg_key; 405 esp->conf.key_len = (x->ealg->alg_key_len+7)/8; 406 if (x->props.ealgo == SADB_EALG_NULL) 407 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_ECB); 408 else 409 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_CBC); 410 if (esp->conf.tfm == NULL) 411 goto error; 412 esp->conf.ivlen = crypto_tfm_alg_ivsize(esp->conf.tfm); 413 esp->conf.padlen = 0; 414 if (esp->conf.ivlen) { 415 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL); 416 if (unlikely(esp->conf.ivec == NULL)) 417 goto error; 418 get_random_bytes(esp->conf.ivec, esp->conf.ivlen); 419 } 420 if (crypto_cipher_setkey(esp->conf.tfm, esp->conf.key, esp->conf.key_len)) 421 goto error; 422 x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen; 423 if (x->props.mode) 424 x->props.header_len += sizeof(struct iphdr); 425 if (x->encap) { 426 struct xfrm_encap_tmpl *encap = x->encap; 427 428 switch (encap->encap_type) { 429 default: 430 goto error; 431 case UDP_ENCAP_ESPINUDP: 432 x->props.header_len += sizeof(struct udphdr); 433 break; 434 case UDP_ENCAP_ESPINUDP_NON_IKE: 435 x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32); 436 break; 437 } 438 } 439 x->data = esp; 440 x->props.trailer_len = esp4_get_max_size(x, 0) - x->props.header_len; 441 return 0; 442 443 error: 444 x->data = esp; 445 esp_destroy(x); 446 x->data = NULL; 447 return -EINVAL; 448 } 449 450 static struct xfrm_type esp_type = 451 { 452 .description = "ESP4", 453 .owner = THIS_MODULE, 454 .proto = IPPROTO_ESP, 455 .init_state = esp_init_state, 456 .destructor = esp_destroy, 457 .get_max_size = esp4_get_max_size, 458 .input = esp_input, 459 .post_input = esp_post_input, 460 .output = esp_output 461 }; 462 463 static struct net_protocol esp4_protocol = { 464 .handler = xfrm4_rcv, 465 .err_handler = esp4_err, 466 .no_policy = 1, 467 }; 468 469 static int __init esp4_init(void) 470 { 471 struct xfrm_decap_state decap; 472 473 if (sizeof(struct esp_decap_data) > 474 sizeof(decap.decap_data)) { 475 extern void decap_data_too_small(void); 476 477 decap_data_too_small(); 478 } 479 480 if (xfrm_register_type(&esp_type, AF_INET) < 0) { 481 printk(KERN_INFO "ip esp init: can't add xfrm type\n"); 482 return -EAGAIN; 483 } 484 if (inet_add_protocol(&esp4_protocol, IPPROTO_ESP) < 0) { 485 printk(KERN_INFO "ip esp init: can't add protocol\n"); 486 xfrm_unregister_type(&esp_type, AF_INET); 487 return -EAGAIN; 488 } 489 return 0; 490 } 491 492 static void __exit esp4_fini(void) 493 { 494 if (inet_del_protocol(&esp4_protocol, IPPROTO_ESP) < 0) 495 printk(KERN_INFO "ip esp close: can't remove protocol\n"); 496 if (xfrm_unregister_type(&esp_type, AF_INET) < 0) 497 printk(KERN_INFO "ip esp close: can't remove xfrm type\n"); 498 } 499 500 module_init(esp4_init); 501 module_exit(esp4_fini); 502 MODULE_LICENSE("GPL"); 503