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 xfrm_aevent_doreplay(x); 94 95 if (esp->conf.ivlen) 96 crypto_cipher_set_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); 97 98 do { 99 struct scatterlist *sg = &esp->sgbuf[0]; 100 101 if (unlikely(nfrags > ESP_NUM_FAST_SG)) { 102 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); 103 if (!sg) 104 goto error; 105 } 106 skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen); 107 crypto_cipher_encrypt(tfm, sg, sg, clen); 108 if (unlikely(sg != &esp->sgbuf[0])) 109 kfree(sg); 110 } while (0); 111 112 if (esp->conf.ivlen) { 113 memcpy(esph->enc_data, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); 114 crypto_cipher_get_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); 115 } 116 117 if (esp->auth.icv_full_len) { 118 esp->auth.icv(esp, skb, (u8*)esph-skb->data, 119 sizeof(struct ip_esp_hdr) + esp->conf.ivlen+clen, trailer->tail); 120 pskb_put(skb, trailer, alen); 121 } 122 123 ip_send_check(top_iph); 124 125 err = 0; 126 127 error: 128 return err; 129 } 130 131 /* 132 * Note: detecting truncated vs. non-truncated authentication data is very 133 * expensive, so we only support truncated data, which is the recommended 134 * and common case. 135 */ 136 static int esp_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb) 137 { 138 struct iphdr *iph; 139 struct ip_esp_hdr *esph; 140 struct esp_data *esp = x->data; 141 struct sk_buff *trailer; 142 int blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4); 143 int alen = esp->auth.icv_trunc_len; 144 int elen = skb->len - sizeof(struct ip_esp_hdr) - esp->conf.ivlen - alen; 145 int nfrags; 146 int encap_len = 0; 147 u8 nexthdr[2]; 148 struct scatterlist *sg; 149 u8 workbuf[60]; 150 int padlen; 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 sg = &esp->sgbuf[0]; 187 188 if (unlikely(nfrags > ESP_NUM_FAST_SG)) { 189 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); 190 if (!sg) 191 goto out; 192 } 193 skb_to_sgvec(skb, sg, sizeof(struct ip_esp_hdr) + esp->conf.ivlen, elen); 194 crypto_cipher_decrypt(esp->conf.tfm, sg, sg, elen); 195 if (unlikely(sg != &esp->sgbuf[0])) 196 kfree(sg); 197 198 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2)) 199 BUG(); 200 201 padlen = nexthdr[0]; 202 if (padlen+2 >= elen) 203 goto out; 204 205 /* ... check padding bits here. Silly. :-) */ 206 207 if (x->encap) { 208 struct xfrm_encap_tmpl *encap = x->encap; 209 struct udphdr *uh; 210 211 if (encap->encap_type != decap->decap_type) 212 goto out; 213 214 uh = (struct udphdr *)(iph + 1); 215 encap_len = (void*)esph - (void*)uh; 216 217 /* 218 * 1) if the NAT-T peer's IP or port changed then 219 * advertize the change to the keying daemon. 220 * This is an inbound SA, so just compare 221 * SRC ports. 222 */ 223 if (iph->saddr != x->props.saddr.a4 || 224 uh->source != encap->encap_sport) { 225 xfrm_address_t ipaddr; 226 227 ipaddr.a4 = iph->saddr; 228 km_new_mapping(x, &ipaddr, uh->source); 229 230 /* XXX: perhaps add an extra 231 * policy check here, to see 232 * if we should allow or 233 * reject a packet from a 234 * different source 235 * address/port. 236 */ 237 } 238 239 /* 240 * 2) ignore UDP/TCP checksums in case 241 * of NAT-T in Transport Mode, or 242 * perform other post-processing fixes 243 * as per draft-ietf-ipsec-udp-encaps-06, 244 * section 3.1.2 245 */ 246 if (!x->props.mode) 247 skb->ip_summed = CHECKSUM_UNNECESSARY; 248 } 249 250 iph->protocol = nexthdr[1]; 251 pskb_trim(skb, skb->len - alen - padlen - 2); 252 memcpy(workbuf, skb->nh.raw, iph->ihl*4); 253 skb->h.raw = skb_pull(skb, sizeof(struct ip_esp_hdr) + esp->conf.ivlen); 254 skb->nh.raw += encap_len + sizeof(struct ip_esp_hdr) + esp->conf.ivlen; 255 memcpy(skb->nh.raw, workbuf, iph->ihl*4); 256 skb->nh.iph->tot_len = htons(skb->len); 257 258 return 0; 259 260 out: 261 return -EINVAL; 262 } 263 264 static u32 esp4_get_max_size(struct xfrm_state *x, int mtu) 265 { 266 struct esp_data *esp = x->data; 267 u32 blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4); 268 269 if (x->props.mode) { 270 mtu = ALIGN(mtu + 2, blksize); 271 } else { 272 /* The worst case. */ 273 mtu = ALIGN(mtu + 2, 4) + blksize - 4; 274 } 275 if (esp->conf.padlen) 276 mtu = ALIGN(mtu, esp->conf.padlen); 277 278 return mtu + x->props.header_len + esp->auth.icv_trunc_len; 279 } 280 281 static void esp4_err(struct sk_buff *skb, u32 info) 282 { 283 struct iphdr *iph = (struct iphdr*)skb->data; 284 struct ip_esp_hdr *esph = (struct ip_esp_hdr*)(skb->data+(iph->ihl<<2)); 285 struct xfrm_state *x; 286 287 if (skb->h.icmph->type != ICMP_DEST_UNREACH || 288 skb->h.icmph->code != ICMP_FRAG_NEEDED) 289 return; 290 291 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET); 292 if (!x) 293 return; 294 NETDEBUG(KERN_DEBUG "pmtu discovery on SA ESP/%08x/%08x\n", 295 ntohl(esph->spi), ntohl(iph->daddr)); 296 xfrm_state_put(x); 297 } 298 299 static void esp_destroy(struct xfrm_state *x) 300 { 301 struct esp_data *esp = x->data; 302 303 if (!esp) 304 return; 305 306 crypto_free_tfm(esp->conf.tfm); 307 esp->conf.tfm = NULL; 308 kfree(esp->conf.ivec); 309 esp->conf.ivec = NULL; 310 crypto_free_tfm(esp->auth.tfm); 311 esp->auth.tfm = NULL; 312 kfree(esp->auth.work_icv); 313 esp->auth.work_icv = NULL; 314 kfree(esp); 315 } 316 317 static int esp_init_state(struct xfrm_state *x) 318 { 319 struct esp_data *esp = NULL; 320 321 /* null auth and encryption can have zero length keys */ 322 if (x->aalg) { 323 if (x->aalg->alg_key_len > 512) 324 goto error; 325 } 326 if (x->ealg == NULL) 327 goto error; 328 329 esp = kmalloc(sizeof(*esp), GFP_KERNEL); 330 if (esp == NULL) 331 return -ENOMEM; 332 333 memset(esp, 0, sizeof(*esp)); 334 335 if (x->aalg) { 336 struct xfrm_algo_desc *aalg_desc; 337 338 esp->auth.key = x->aalg->alg_key; 339 esp->auth.key_len = (x->aalg->alg_key_len+7)/8; 340 esp->auth.tfm = crypto_alloc_tfm(x->aalg->alg_name, 0); 341 if (esp->auth.tfm == NULL) 342 goto error; 343 esp->auth.icv = esp_hmac_digest; 344 345 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 346 BUG_ON(!aalg_desc); 347 348 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 349 crypto_tfm_alg_digestsize(esp->auth.tfm)) { 350 NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n", 351 x->aalg->alg_name, 352 crypto_tfm_alg_digestsize(esp->auth.tfm), 353 aalg_desc->uinfo.auth.icv_fullbits/8); 354 goto error; 355 } 356 357 esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; 358 esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8; 359 360 esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL); 361 if (!esp->auth.work_icv) 362 goto error; 363 } 364 esp->conf.key = x->ealg->alg_key; 365 esp->conf.key_len = (x->ealg->alg_key_len+7)/8; 366 if (x->props.ealgo == SADB_EALG_NULL) 367 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_ECB); 368 else 369 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_CBC); 370 if (esp->conf.tfm == NULL) 371 goto error; 372 esp->conf.ivlen = crypto_tfm_alg_ivsize(esp->conf.tfm); 373 esp->conf.padlen = 0; 374 if (esp->conf.ivlen) { 375 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL); 376 if (unlikely(esp->conf.ivec == NULL)) 377 goto error; 378 get_random_bytes(esp->conf.ivec, esp->conf.ivlen); 379 } 380 if (crypto_cipher_setkey(esp->conf.tfm, esp->conf.key, esp->conf.key_len)) 381 goto error; 382 x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen; 383 if (x->props.mode) 384 x->props.header_len += sizeof(struct iphdr); 385 if (x->encap) { 386 struct xfrm_encap_tmpl *encap = x->encap; 387 388 switch (encap->encap_type) { 389 default: 390 goto error; 391 case UDP_ENCAP_ESPINUDP: 392 x->props.header_len += sizeof(struct udphdr); 393 break; 394 case UDP_ENCAP_ESPINUDP_NON_IKE: 395 x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32); 396 break; 397 } 398 } 399 x->data = esp; 400 x->props.trailer_len = esp4_get_max_size(x, 0) - x->props.header_len; 401 return 0; 402 403 error: 404 x->data = esp; 405 esp_destroy(x); 406 x->data = NULL; 407 return -EINVAL; 408 } 409 410 static struct xfrm_type esp_type = 411 { 412 .description = "ESP4", 413 .owner = THIS_MODULE, 414 .proto = IPPROTO_ESP, 415 .init_state = esp_init_state, 416 .destructor = esp_destroy, 417 .get_max_size = esp4_get_max_size, 418 .input = esp_input, 419 .output = esp_output 420 }; 421 422 static struct net_protocol esp4_protocol = { 423 .handler = xfrm4_rcv, 424 .err_handler = esp4_err, 425 .no_policy = 1, 426 }; 427 428 static int __init esp4_init(void) 429 { 430 if (xfrm_register_type(&esp_type, AF_INET) < 0) { 431 printk(KERN_INFO "ip esp init: can't add xfrm type\n"); 432 return -EAGAIN; 433 } 434 if (inet_add_protocol(&esp4_protocol, IPPROTO_ESP) < 0) { 435 printk(KERN_INFO "ip esp init: can't add protocol\n"); 436 xfrm_unregister_type(&esp_type, AF_INET); 437 return -EAGAIN; 438 } 439 return 0; 440 } 441 442 static void __exit esp4_fini(void) 443 { 444 if (inet_del_protocol(&esp4_protocol, IPPROTO_ESP) < 0) 445 printk(KERN_INFO "ip esp close: can't remove protocol\n"); 446 if (xfrm_unregister_type(&esp_type, AF_INET) < 0) 447 printk(KERN_INFO "ip esp close: can't remove xfrm type\n"); 448 } 449 450 module_init(esp4_init); 451 module_exit(esp4_fini); 452 MODULE_LICENSE("GPL"); 453