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(printk(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 if (esp->conf.tfm) { 347 crypto_free_tfm(esp->conf.tfm); 348 esp->conf.tfm = NULL; 349 } 350 if (esp->conf.ivec) { 351 kfree(esp->conf.ivec); 352 esp->conf.ivec = NULL; 353 } 354 if (esp->auth.tfm) { 355 crypto_free_tfm(esp->auth.tfm); 356 esp->auth.tfm = NULL; 357 } 358 if (esp->auth.work_icv) { 359 kfree(esp->auth.work_icv); 360 esp->auth.work_icv = NULL; 361 } 362 kfree(esp); 363 } 364 365 static int esp_init_state(struct xfrm_state *x, void *args) 366 { 367 struct esp_data *esp = NULL; 368 369 /* null auth and encryption can have zero length keys */ 370 if (x->aalg) { 371 if (x->aalg->alg_key_len > 512) 372 goto error; 373 } 374 if (x->ealg == NULL) 375 goto error; 376 377 esp = kmalloc(sizeof(*esp), GFP_KERNEL); 378 if (esp == NULL) 379 return -ENOMEM; 380 381 memset(esp, 0, sizeof(*esp)); 382 383 if (x->aalg) { 384 struct xfrm_algo_desc *aalg_desc; 385 386 esp->auth.key = x->aalg->alg_key; 387 esp->auth.key_len = (x->aalg->alg_key_len+7)/8; 388 esp->auth.tfm = crypto_alloc_tfm(x->aalg->alg_name, 0); 389 if (esp->auth.tfm == NULL) 390 goto error; 391 esp->auth.icv = esp_hmac_digest; 392 393 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 394 BUG_ON(!aalg_desc); 395 396 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 397 crypto_tfm_alg_digestsize(esp->auth.tfm)) { 398 NETDEBUG(printk(KERN_INFO "ESP: %s digestsize %u != %hu\n", 399 x->aalg->alg_name, 400 crypto_tfm_alg_digestsize(esp->auth.tfm), 401 aalg_desc->uinfo.auth.icv_fullbits/8)); 402 goto error; 403 } 404 405 esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; 406 esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8; 407 408 esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL); 409 if (!esp->auth.work_icv) 410 goto error; 411 } 412 esp->conf.key = x->ealg->alg_key; 413 esp->conf.key_len = (x->ealg->alg_key_len+7)/8; 414 if (x->props.ealgo == SADB_EALG_NULL) 415 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_ECB); 416 else 417 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_CBC); 418 if (esp->conf.tfm == NULL) 419 goto error; 420 esp->conf.ivlen = crypto_tfm_alg_ivsize(esp->conf.tfm); 421 esp->conf.padlen = 0; 422 if (esp->conf.ivlen) { 423 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL); 424 if (unlikely(esp->conf.ivec == NULL)) 425 goto error; 426 get_random_bytes(esp->conf.ivec, esp->conf.ivlen); 427 } 428 if (crypto_cipher_setkey(esp->conf.tfm, esp->conf.key, esp->conf.key_len)) 429 goto error; 430 x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen; 431 if (x->props.mode) 432 x->props.header_len += sizeof(struct iphdr); 433 if (x->encap) { 434 struct xfrm_encap_tmpl *encap = x->encap; 435 436 switch (encap->encap_type) { 437 default: 438 goto error; 439 case UDP_ENCAP_ESPINUDP: 440 x->props.header_len += sizeof(struct udphdr); 441 break; 442 case UDP_ENCAP_ESPINUDP_NON_IKE: 443 x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32); 444 break; 445 } 446 } 447 x->data = esp; 448 x->props.trailer_len = esp4_get_max_size(x, 0) - x->props.header_len; 449 return 0; 450 451 error: 452 x->data = esp; 453 esp_destroy(x); 454 x->data = NULL; 455 return -EINVAL; 456 } 457 458 static struct xfrm_type esp_type = 459 { 460 .description = "ESP4", 461 .owner = THIS_MODULE, 462 .proto = IPPROTO_ESP, 463 .init_state = esp_init_state, 464 .destructor = esp_destroy, 465 .get_max_size = esp4_get_max_size, 466 .input = esp_input, 467 .post_input = esp_post_input, 468 .output = esp_output 469 }; 470 471 static struct net_protocol esp4_protocol = { 472 .handler = xfrm4_rcv, 473 .err_handler = esp4_err, 474 .no_policy = 1, 475 }; 476 477 static int __init esp4_init(void) 478 { 479 struct xfrm_decap_state decap; 480 481 if (sizeof(struct esp_decap_data) < 482 sizeof(decap.decap_data)) { 483 extern void decap_data_too_small(void); 484 485 decap_data_too_small(); 486 } 487 488 if (xfrm_register_type(&esp_type, AF_INET) < 0) { 489 printk(KERN_INFO "ip esp init: can't add xfrm type\n"); 490 return -EAGAIN; 491 } 492 if (inet_add_protocol(&esp4_protocol, IPPROTO_ESP) < 0) { 493 printk(KERN_INFO "ip esp init: can't add protocol\n"); 494 xfrm_unregister_type(&esp_type, AF_INET); 495 return -EAGAIN; 496 } 497 return 0; 498 } 499 500 static void __exit esp4_fini(void) 501 { 502 if (inet_del_protocol(&esp4_protocol, IPPROTO_ESP) < 0) 503 printk(KERN_INFO "ip esp close: can't remove protocol\n"); 504 if (xfrm_unregister_type(&esp_type, AF_INET) < 0) 505 printk(KERN_INFO "ip esp close: can't remove xfrm type\n"); 506 } 507 508 module_init(esp4_init); 509 module_exit(esp4_fini); 510 MODULE_LICENSE("GPL"); 511