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