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 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 uh = (struct udphdr *)(iph + 1); 212 encap_len = (void*)esph - (void*)uh; 213 214 /* 215 * 1) if the NAT-T peer's IP or port changed then 216 * advertize the change to the keying daemon. 217 * This is an inbound SA, so just compare 218 * SRC ports. 219 */ 220 if (iph->saddr != x->props.saddr.a4 || 221 uh->source != encap->encap_sport) { 222 xfrm_address_t ipaddr; 223 224 ipaddr.a4 = iph->saddr; 225 km_new_mapping(x, &ipaddr, uh->source); 226 227 /* XXX: perhaps add an extra 228 * policy check here, to see 229 * if we should allow or 230 * reject a packet from a 231 * different source 232 * address/port. 233 */ 234 } 235 236 /* 237 * 2) ignore UDP/TCP checksums in case 238 * of NAT-T in Transport Mode, or 239 * perform other post-processing fixes 240 * as per draft-ietf-ipsec-udp-encaps-06, 241 * section 3.1.2 242 */ 243 if (!x->props.mode) 244 skb->ip_summed = CHECKSUM_UNNECESSARY; 245 } 246 247 iph->protocol = nexthdr[1]; 248 pskb_trim(skb, skb->len - alen - padlen - 2); 249 memcpy(workbuf, skb->nh.raw, iph->ihl*4); 250 skb->h.raw = skb_pull(skb, sizeof(struct ip_esp_hdr) + esp->conf.ivlen); 251 skb->nh.raw += encap_len + sizeof(struct ip_esp_hdr) + esp->conf.ivlen; 252 memcpy(skb->nh.raw, workbuf, iph->ihl*4); 253 skb->nh.iph->tot_len = htons(skb->len); 254 255 return 0; 256 257 out: 258 return -EINVAL; 259 } 260 261 static u32 esp4_get_max_size(struct xfrm_state *x, int mtu) 262 { 263 struct esp_data *esp = x->data; 264 u32 blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4); 265 266 if (x->props.mode) { 267 mtu = ALIGN(mtu + 2, blksize); 268 } else { 269 /* The worst case. */ 270 mtu = ALIGN(mtu + 2, 4) + blksize - 4; 271 } 272 if (esp->conf.padlen) 273 mtu = ALIGN(mtu, esp->conf.padlen); 274 275 return mtu + x->props.header_len + esp->auth.icv_trunc_len; 276 } 277 278 static void esp4_err(struct sk_buff *skb, u32 info) 279 { 280 struct iphdr *iph = (struct iphdr*)skb->data; 281 struct ip_esp_hdr *esph = (struct ip_esp_hdr*)(skb->data+(iph->ihl<<2)); 282 struct xfrm_state *x; 283 284 if (skb->h.icmph->type != ICMP_DEST_UNREACH || 285 skb->h.icmph->code != ICMP_FRAG_NEEDED) 286 return; 287 288 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET); 289 if (!x) 290 return; 291 NETDEBUG(KERN_DEBUG "pmtu discovery on SA ESP/%08x/%08x\n", 292 ntohl(esph->spi), ntohl(iph->daddr)); 293 xfrm_state_put(x); 294 } 295 296 static void esp_destroy(struct xfrm_state *x) 297 { 298 struct esp_data *esp = x->data; 299 300 if (!esp) 301 return; 302 303 crypto_free_tfm(esp->conf.tfm); 304 esp->conf.tfm = NULL; 305 kfree(esp->conf.ivec); 306 esp->conf.ivec = NULL; 307 crypto_free_tfm(esp->auth.tfm); 308 esp->auth.tfm = NULL; 309 kfree(esp->auth.work_icv); 310 esp->auth.work_icv = NULL; 311 kfree(esp); 312 } 313 314 static int esp_init_state(struct xfrm_state *x) 315 { 316 struct esp_data *esp = NULL; 317 318 /* null auth and encryption can have zero length keys */ 319 if (x->aalg) { 320 if (x->aalg->alg_key_len > 512) 321 goto error; 322 } 323 if (x->ealg == NULL) 324 goto error; 325 326 esp = kmalloc(sizeof(*esp), GFP_KERNEL); 327 if (esp == NULL) 328 return -ENOMEM; 329 330 memset(esp, 0, sizeof(*esp)); 331 332 if (x->aalg) { 333 struct xfrm_algo_desc *aalg_desc; 334 335 esp->auth.key = x->aalg->alg_key; 336 esp->auth.key_len = (x->aalg->alg_key_len+7)/8; 337 esp->auth.tfm = crypto_alloc_tfm(x->aalg->alg_name, 0); 338 if (esp->auth.tfm == NULL) 339 goto error; 340 esp->auth.icv = esp_hmac_digest; 341 342 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 343 BUG_ON(!aalg_desc); 344 345 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 346 crypto_tfm_alg_digestsize(esp->auth.tfm)) { 347 NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n", 348 x->aalg->alg_name, 349 crypto_tfm_alg_digestsize(esp->auth.tfm), 350 aalg_desc->uinfo.auth.icv_fullbits/8); 351 goto error; 352 } 353 354 esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; 355 esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8; 356 357 esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL); 358 if (!esp->auth.work_icv) 359 goto error; 360 } 361 esp->conf.key = x->ealg->alg_key; 362 esp->conf.key_len = (x->ealg->alg_key_len+7)/8; 363 if (x->props.ealgo == SADB_EALG_NULL) 364 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_ECB); 365 else 366 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_CBC); 367 if (esp->conf.tfm == NULL) 368 goto error; 369 esp->conf.ivlen = crypto_tfm_alg_ivsize(esp->conf.tfm); 370 esp->conf.padlen = 0; 371 if (esp->conf.ivlen) { 372 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL); 373 if (unlikely(esp->conf.ivec == NULL)) 374 goto error; 375 get_random_bytes(esp->conf.ivec, esp->conf.ivlen); 376 } 377 if (crypto_cipher_setkey(esp->conf.tfm, esp->conf.key, esp->conf.key_len)) 378 goto error; 379 x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen; 380 if (x->props.mode) 381 x->props.header_len += sizeof(struct iphdr); 382 if (x->encap) { 383 struct xfrm_encap_tmpl *encap = x->encap; 384 385 switch (encap->encap_type) { 386 default: 387 goto error; 388 case UDP_ENCAP_ESPINUDP: 389 x->props.header_len += sizeof(struct udphdr); 390 break; 391 case UDP_ENCAP_ESPINUDP_NON_IKE: 392 x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32); 393 break; 394 } 395 } 396 x->data = esp; 397 x->props.trailer_len = esp4_get_max_size(x, 0) - x->props.header_len; 398 return 0; 399 400 error: 401 x->data = esp; 402 esp_destroy(x); 403 x->data = NULL; 404 return -EINVAL; 405 } 406 407 static struct xfrm_type esp_type = 408 { 409 .description = "ESP4", 410 .owner = THIS_MODULE, 411 .proto = IPPROTO_ESP, 412 .init_state = esp_init_state, 413 .destructor = esp_destroy, 414 .get_max_size = esp4_get_max_size, 415 .input = esp_input, 416 .output = esp_output 417 }; 418 419 static struct net_protocol esp4_protocol = { 420 .handler = xfrm4_rcv, 421 .err_handler = esp4_err, 422 .no_policy = 1, 423 }; 424 425 static int __init esp4_init(void) 426 { 427 if (xfrm_register_type(&esp_type, AF_INET) < 0) { 428 printk(KERN_INFO "ip esp init: can't add xfrm type\n"); 429 return -EAGAIN; 430 } 431 if (inet_add_protocol(&esp4_protocol, IPPROTO_ESP) < 0) { 432 printk(KERN_INFO "ip esp init: can't add protocol\n"); 433 xfrm_unregister_type(&esp_type, AF_INET); 434 return -EAGAIN; 435 } 436 return 0; 437 } 438 439 static void __exit esp4_fini(void) 440 { 441 if (inet_del_protocol(&esp4_protocol, IPPROTO_ESP) < 0) 442 printk(KERN_INFO "ip esp close: can't remove protocol\n"); 443 if (xfrm_unregister_type(&esp_type, AF_INET) < 0) 444 printk(KERN_INFO "ip esp close: can't remove xfrm type\n"); 445 } 446 447 module_init(esp4_init); 448 module_exit(esp4_fini); 449 MODULE_LICENSE("GPL"); 450