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/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 /* decapsulation data for use when post-processing */ 16 struct esp_decap_data { 17 xfrm_address_t saddr; 18 __u16 sport; 19 __u8 proto; 20 }; 21 22 static int esp_output(struct xfrm_state *x, struct sk_buff *skb) 23 { 24 int err; 25 struct iphdr *top_iph; 26 struct ip_esp_hdr *esph; 27 struct crypto_tfm *tfm; 28 struct esp_data *esp; 29 struct sk_buff *trailer; 30 int blksize; 31 int clen; 32 int alen; 33 int nfrags; 34 35 /* Strip IP+ESP header. */ 36 __skb_pull(skb, skb->h.raw - skb->data); 37 /* Now skb is pure payload to encrypt */ 38 39 err = -ENOMEM; 40 41 /* Round to block size */ 42 clen = skb->len; 43 44 esp = x->data; 45 alen = esp->auth.icv_trunc_len; 46 tfm = esp->conf.tfm; 47 blksize = ALIGN(crypto_tfm_alg_blocksize(tfm), 4); 48 clen = ALIGN(clen + 2, blksize); 49 if (esp->conf.padlen) 50 clen = ALIGN(clen, esp->conf.padlen); 51 52 if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0) 53 goto error; 54 55 /* Fill padding... */ 56 do { 57 int i; 58 for (i=0; i<clen-skb->len - 2; i++) 59 *(u8*)(trailer->tail + i) = i+1; 60 } while (0); 61 *(u8*)(trailer->tail + clen-skb->len - 2) = (clen - skb->len)-2; 62 pskb_put(skb, trailer, clen - skb->len); 63 64 __skb_push(skb, skb->data - skb->nh.raw); 65 top_iph = skb->nh.iph; 66 esph = (struct ip_esp_hdr *)(skb->nh.raw + top_iph->ihl*4); 67 top_iph->tot_len = htons(skb->len + alen); 68 *(u8*)(trailer->tail - 1) = top_iph->protocol; 69 70 /* this is non-NULL only with UDP Encapsulation */ 71 if (x->encap) { 72 struct xfrm_encap_tmpl *encap = x->encap; 73 struct udphdr *uh; 74 u32 *udpdata32; 75 76 uh = (struct udphdr *)esph; 77 uh->source = encap->encap_sport; 78 uh->dest = encap->encap_dport; 79 uh->len = htons(skb->len + alen - top_iph->ihl*4); 80 uh->check = 0; 81 82 switch (encap->encap_type) { 83 default: 84 case UDP_ENCAP_ESPINUDP: 85 esph = (struct ip_esp_hdr *)(uh + 1); 86 break; 87 case UDP_ENCAP_ESPINUDP_NON_IKE: 88 udpdata32 = (u32 *)(uh + 1); 89 udpdata32[0] = udpdata32[1] = 0; 90 esph = (struct ip_esp_hdr *)(udpdata32 + 2); 91 break; 92 } 93 94 top_iph->protocol = IPPROTO_UDP; 95 } else 96 top_iph->protocol = IPPROTO_ESP; 97 98 esph->spi = x->id.spi; 99 esph->seq_no = htonl(++x->replay.oseq); 100 101 if (esp->conf.ivlen) 102 crypto_cipher_set_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); 103 104 do { 105 struct scatterlist *sg = &esp->sgbuf[0]; 106 107 if (unlikely(nfrags > ESP_NUM_FAST_SG)) { 108 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); 109 if (!sg) 110 goto error; 111 } 112 skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen); 113 crypto_cipher_encrypt(tfm, sg, sg, clen); 114 if (unlikely(sg != &esp->sgbuf[0])) 115 kfree(sg); 116 } while (0); 117 118 if (esp->conf.ivlen) { 119 memcpy(esph->enc_data, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); 120 crypto_cipher_get_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); 121 } 122 123 if (esp->auth.icv_full_len) { 124 esp->auth.icv(esp, skb, (u8*)esph-skb->data, 125 sizeof(struct ip_esp_hdr) + esp->conf.ivlen+clen, trailer->tail); 126 pskb_put(skb, trailer, alen); 127 } 128 129 ip_send_check(top_iph); 130 131 err = 0; 132 133 error: 134 return err; 135 } 136 137 /* 138 * Note: detecting truncated vs. non-truncated authentication data is very 139 * expensive, so we only support truncated data, which is the recommended 140 * and common case. 141 */ 142 static int esp_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb) 143 { 144 struct iphdr *iph; 145 struct ip_esp_hdr *esph; 146 struct esp_data *esp = x->data; 147 struct sk_buff *trailer; 148 int blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4); 149 int alen = esp->auth.icv_trunc_len; 150 int elen = skb->len - sizeof(struct ip_esp_hdr) - esp->conf.ivlen - alen; 151 int nfrags; 152 int encap_len = 0; 153 154 if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr))) 155 goto out; 156 157 if (elen <= 0 || (elen & (blksize-1))) 158 goto out; 159 160 /* If integrity check is required, do this. */ 161 if (esp->auth.icv_full_len) { 162 u8 sum[esp->auth.icv_full_len]; 163 u8 sum1[alen]; 164 165 esp->auth.icv(esp, skb, 0, skb->len-alen, sum); 166 167 if (skb_copy_bits(skb, skb->len-alen, sum1, alen)) 168 BUG(); 169 170 if (unlikely(memcmp(sum, sum1, alen))) { 171 x->stats.integrity_failed++; 172 goto out; 173 } 174 } 175 176 if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) 177 goto out; 178 179 skb->ip_summed = CHECKSUM_NONE; 180 181 esph = (struct ip_esp_hdr*)skb->data; 182 iph = skb->nh.iph; 183 184 /* Get ivec. This can be wrong, check against another impls. */ 185 if (esp->conf.ivlen) 186 crypto_cipher_set_iv(esp->conf.tfm, esph->enc_data, crypto_tfm_alg_ivsize(esp->conf.tfm)); 187 188 { 189 u8 nexthdr[2]; 190 struct scatterlist *sg = &esp->sgbuf[0]; 191 u8 workbuf[60]; 192 int padlen; 193 194 if (unlikely(nfrags > ESP_NUM_FAST_SG)) { 195 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); 196 if (!sg) 197 goto out; 198 } 199 skb_to_sgvec(skb, sg, sizeof(struct ip_esp_hdr) + esp->conf.ivlen, elen); 200 crypto_cipher_decrypt(esp->conf.tfm, sg, sg, elen); 201 if (unlikely(sg != &esp->sgbuf[0])) 202 kfree(sg); 203 204 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2)) 205 BUG(); 206 207 padlen = nexthdr[0]; 208 if (padlen+2 >= elen) 209 goto out; 210 211 /* ... check padding bits here. Silly. :-) */ 212 213 if (x->encap && decap && decap->decap_type) { 214 struct esp_decap_data *encap_data; 215 struct udphdr *uh = (struct udphdr *) (iph+1); 216 217 encap_data = (struct esp_decap_data *) (decap->decap_data); 218 encap_data->proto = 0; 219 220 switch (decap->decap_type) { 221 case UDP_ENCAP_ESPINUDP: 222 case UDP_ENCAP_ESPINUDP_NON_IKE: 223 encap_data->proto = AF_INET; 224 encap_data->saddr.a4 = iph->saddr; 225 encap_data->sport = uh->source; 226 encap_len = (void*)esph - (void*)uh; 227 break; 228 229 default: 230 goto out; 231 } 232 } 233 234 iph->protocol = nexthdr[1]; 235 pskb_trim(skb, skb->len - alen - padlen - 2); 236 memcpy(workbuf, skb->nh.raw, iph->ihl*4); 237 skb->h.raw = skb_pull(skb, sizeof(struct ip_esp_hdr) + esp->conf.ivlen); 238 skb->nh.raw += encap_len + sizeof(struct ip_esp_hdr) + esp->conf.ivlen; 239 memcpy(skb->nh.raw, workbuf, iph->ihl*4); 240 skb->nh.iph->tot_len = htons(skb->len); 241 } 242 243 return 0; 244 245 out: 246 return -EINVAL; 247 } 248 249 static int esp_post_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb) 250 { 251 252 if (x->encap) { 253 struct xfrm_encap_tmpl *encap; 254 struct esp_decap_data *decap_data; 255 256 encap = x->encap; 257 decap_data = (struct esp_decap_data *)(decap->decap_data); 258 259 /* first, make sure that the decap type == the encap type */ 260 if (encap->encap_type != decap->decap_type) 261 return -EINVAL; 262 263 switch (encap->encap_type) { 264 default: 265 case UDP_ENCAP_ESPINUDP: 266 case UDP_ENCAP_ESPINUDP_NON_IKE: 267 /* 268 * 1) if the NAT-T peer's IP or port changed then 269 * advertize the change to the keying daemon. 270 * This is an inbound SA, so just compare 271 * SRC ports. 272 */ 273 if (decap_data->proto == AF_INET && 274 (decap_data->saddr.a4 != x->props.saddr.a4 || 275 decap_data->sport != encap->encap_sport)) { 276 xfrm_address_t ipaddr; 277 278 ipaddr.a4 = decap_data->saddr.a4; 279 km_new_mapping(x, &ipaddr, decap_data->sport); 280 281 /* XXX: perhaps add an extra 282 * policy check here, to see 283 * if we should allow or 284 * reject a packet from a 285 * different source 286 * address/port. 287 */ 288 } 289 290 /* 291 * 2) ignore UDP/TCP checksums in case 292 * of NAT-T in Transport Mode, or 293 * perform other post-processing fixes 294 * as per * draft-ietf-ipsec-udp-encaps-06, 295 * section 3.1.2 296 */ 297 if (!x->props.mode) 298 skb->ip_summed = CHECKSUM_UNNECESSARY; 299 300 break; 301 } 302 } 303 return 0; 304 } 305 306 static u32 esp4_get_max_size(struct xfrm_state *x, int mtu) 307 { 308 struct esp_data *esp = x->data; 309 u32 blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4); 310 311 if (x->props.mode) { 312 mtu = ALIGN(mtu + 2, blksize); 313 } else { 314 /* The worst case. */ 315 mtu = ALIGN(mtu + 2, 4) + blksize - 4; 316 } 317 if (esp->conf.padlen) 318 mtu = ALIGN(mtu, esp->conf.padlen); 319 320 return mtu + x->props.header_len + esp->auth.icv_trunc_len; 321 } 322 323 static void esp4_err(struct sk_buff *skb, u32 info) 324 { 325 struct iphdr *iph = (struct iphdr*)skb->data; 326 struct ip_esp_hdr *esph = (struct ip_esp_hdr*)(skb->data+(iph->ihl<<2)); 327 struct xfrm_state *x; 328 329 if (skb->h.icmph->type != ICMP_DEST_UNREACH || 330 skb->h.icmph->code != ICMP_FRAG_NEEDED) 331 return; 332 333 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET); 334 if (!x) 335 return; 336 NETDEBUG(KERN_DEBUG "pmtu discovery on SA ESP/%08x/%08x\n", 337 ntohl(esph->spi), ntohl(iph->daddr)); 338 xfrm_state_put(x); 339 } 340 341 static void esp_destroy(struct xfrm_state *x) 342 { 343 struct esp_data *esp = x->data; 344 345 if (!esp) 346 return; 347 348 crypto_free_tfm(esp->conf.tfm); 349 esp->conf.tfm = NULL; 350 kfree(esp->conf.ivec); 351 esp->conf.ivec = NULL; 352 crypto_free_tfm(esp->auth.tfm); 353 esp->auth.tfm = NULL; 354 kfree(esp->auth.work_icv); 355 esp->auth.work_icv = NULL; 356 kfree(esp); 357 } 358 359 static int esp_init_state(struct xfrm_state *x) 360 { 361 struct esp_data *esp = NULL; 362 363 /* null auth and encryption can have zero length keys */ 364 if (x->aalg) { 365 if (x->aalg->alg_key_len > 512) 366 goto error; 367 } 368 if (x->ealg == NULL) 369 goto error; 370 371 esp = kmalloc(sizeof(*esp), GFP_KERNEL); 372 if (esp == NULL) 373 return -ENOMEM; 374 375 memset(esp, 0, sizeof(*esp)); 376 377 if (x->aalg) { 378 struct xfrm_algo_desc *aalg_desc; 379 380 esp->auth.key = x->aalg->alg_key; 381 esp->auth.key_len = (x->aalg->alg_key_len+7)/8; 382 esp->auth.tfm = crypto_alloc_tfm(x->aalg->alg_name, 0); 383 if (esp->auth.tfm == NULL) 384 goto error; 385 esp->auth.icv = esp_hmac_digest; 386 387 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 388 BUG_ON(!aalg_desc); 389 390 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 391 crypto_tfm_alg_digestsize(esp->auth.tfm)) { 392 NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n", 393 x->aalg->alg_name, 394 crypto_tfm_alg_digestsize(esp->auth.tfm), 395 aalg_desc->uinfo.auth.icv_fullbits/8); 396 goto error; 397 } 398 399 esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; 400 esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8; 401 402 esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL); 403 if (!esp->auth.work_icv) 404 goto error; 405 } 406 esp->conf.key = x->ealg->alg_key; 407 esp->conf.key_len = (x->ealg->alg_key_len+7)/8; 408 if (x->props.ealgo == SADB_EALG_NULL) 409 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_ECB); 410 else 411 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_CBC); 412 if (esp->conf.tfm == NULL) 413 goto error; 414 esp->conf.ivlen = crypto_tfm_alg_ivsize(esp->conf.tfm); 415 esp->conf.padlen = 0; 416 if (esp->conf.ivlen) { 417 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL); 418 if (unlikely(esp->conf.ivec == NULL)) 419 goto error; 420 get_random_bytes(esp->conf.ivec, esp->conf.ivlen); 421 } 422 if (crypto_cipher_setkey(esp->conf.tfm, esp->conf.key, esp->conf.key_len)) 423 goto error; 424 x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen; 425 if (x->props.mode) 426 x->props.header_len += sizeof(struct iphdr); 427 if (x->encap) { 428 struct xfrm_encap_tmpl *encap = x->encap; 429 430 switch (encap->encap_type) { 431 default: 432 goto error; 433 case UDP_ENCAP_ESPINUDP: 434 x->props.header_len += sizeof(struct udphdr); 435 break; 436 case UDP_ENCAP_ESPINUDP_NON_IKE: 437 x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32); 438 break; 439 } 440 } 441 x->data = esp; 442 x->props.trailer_len = esp4_get_max_size(x, 0) - x->props.header_len; 443 return 0; 444 445 error: 446 x->data = esp; 447 esp_destroy(x); 448 x->data = NULL; 449 return -EINVAL; 450 } 451 452 static struct xfrm_type esp_type = 453 { 454 .description = "ESP4", 455 .owner = THIS_MODULE, 456 .proto = IPPROTO_ESP, 457 .init_state = esp_init_state, 458 .destructor = esp_destroy, 459 .get_max_size = esp4_get_max_size, 460 .input = esp_input, 461 .post_input = esp_post_input, 462 .output = esp_output 463 }; 464 465 static struct net_protocol esp4_protocol = { 466 .handler = xfrm4_rcv, 467 .err_handler = esp4_err, 468 .no_policy = 1, 469 }; 470 471 static int __init esp4_init(void) 472 { 473 struct xfrm_decap_state decap; 474 475 if (sizeof(struct esp_decap_data) > 476 sizeof(decap.decap_data)) { 477 extern void decap_data_too_small(void); 478 479 decap_data_too_small(); 480 } 481 482 if (xfrm_register_type(&esp_type, AF_INET) < 0) { 483 printk(KERN_INFO "ip esp init: can't add xfrm type\n"); 484 return -EAGAIN; 485 } 486 if (inet_add_protocol(&esp4_protocol, IPPROTO_ESP) < 0) { 487 printk(KERN_INFO "ip esp init: can't add protocol\n"); 488 xfrm_unregister_type(&esp_type, AF_INET); 489 return -EAGAIN; 490 } 491 return 0; 492 } 493 494 static void __exit esp4_fini(void) 495 { 496 if (inet_del_protocol(&esp4_protocol, IPPROTO_ESP) < 0) 497 printk(KERN_INFO "ip esp close: can't remove protocol\n"); 498 if (xfrm_unregister_type(&esp_type, AF_INET) < 0) 499 printk(KERN_INFO "ip esp close: can't remove xfrm type\n"); 500 } 501 502 module_init(esp4_init); 503 module_exit(esp4_fini); 504 MODULE_LICENSE("GPL"); 505