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 ihl; 147 u8 nexthdr[2]; 148 struct scatterlist *sg; 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; 179 180 /* Get ivec. This can be wrong, check against another impls. */ 181 if (esp->conf.ivlen) 182 crypto_cipher_set_iv(esp->conf.tfm, esph->enc_data, crypto_tfm_alg_ivsize(esp->conf.tfm)); 183 184 sg = &esp->sgbuf[0]; 185 186 if (unlikely(nfrags > ESP_NUM_FAST_SG)) { 187 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); 188 if (!sg) 189 goto out; 190 } 191 skb_to_sgvec(skb, sg, sizeof(struct ip_esp_hdr) + esp->conf.ivlen, elen); 192 crypto_cipher_decrypt(esp->conf.tfm, sg, sg, elen); 193 if (unlikely(sg != &esp->sgbuf[0])) 194 kfree(sg); 195 196 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2)) 197 BUG(); 198 199 padlen = nexthdr[0]; 200 if (padlen+2 >= elen) 201 goto out; 202 203 /* ... check padding bits here. Silly. :-) */ 204 205 iph = skb->nh.iph; 206 ihl = iph->ihl * 4; 207 208 if (x->encap) { 209 struct xfrm_encap_tmpl *encap = x->encap; 210 struct udphdr *uh = (void *)(skb->nh.raw + ihl); 211 212 /* 213 * 1) if the NAT-T peer's IP or port changed then 214 * advertize the change to the keying daemon. 215 * This is an inbound SA, so just compare 216 * SRC ports. 217 */ 218 if (iph->saddr != x->props.saddr.a4 || 219 uh->source != encap->encap_sport) { 220 xfrm_address_t ipaddr; 221 222 ipaddr.a4 = iph->saddr; 223 km_new_mapping(x, &ipaddr, uh->source); 224 225 /* XXX: perhaps add an extra 226 * policy check here, to see 227 * if we should allow or 228 * reject a packet from a 229 * different source 230 * address/port. 231 */ 232 } 233 234 /* 235 * 2) ignore UDP/TCP checksums in case 236 * of NAT-T in Transport Mode, or 237 * perform other post-processing fixes 238 * as per draft-ietf-ipsec-udp-encaps-06, 239 * section 3.1.2 240 */ 241 if (!x->props.mode) 242 skb->ip_summed = CHECKSUM_UNNECESSARY; 243 } 244 245 iph->protocol = nexthdr[1]; 246 pskb_trim(skb, skb->len - alen - padlen - 2); 247 skb->h.raw = __skb_pull(skb, sizeof(*esph) + esp->conf.ivlen) - ihl; 248 249 return 0; 250 251 out: 252 return -EINVAL; 253 } 254 255 static u32 esp4_get_max_size(struct xfrm_state *x, int mtu) 256 { 257 struct esp_data *esp = x->data; 258 u32 blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4); 259 260 if (x->props.mode) { 261 mtu = ALIGN(mtu + 2, blksize); 262 } else { 263 /* The worst case. */ 264 mtu = ALIGN(mtu + 2, 4) + blksize - 4; 265 } 266 if (esp->conf.padlen) 267 mtu = ALIGN(mtu, esp->conf.padlen); 268 269 return mtu + x->props.header_len + esp->auth.icv_trunc_len; 270 } 271 272 static void esp4_err(struct sk_buff *skb, u32 info) 273 { 274 struct iphdr *iph = (struct iphdr*)skb->data; 275 struct ip_esp_hdr *esph = (struct ip_esp_hdr*)(skb->data+(iph->ihl<<2)); 276 struct xfrm_state *x; 277 278 if (skb->h.icmph->type != ICMP_DEST_UNREACH || 279 skb->h.icmph->code != ICMP_FRAG_NEEDED) 280 return; 281 282 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET); 283 if (!x) 284 return; 285 NETDEBUG(KERN_DEBUG "pmtu discovery on SA ESP/%08x/%08x\n", 286 ntohl(esph->spi), ntohl(iph->daddr)); 287 xfrm_state_put(x); 288 } 289 290 static void esp_destroy(struct xfrm_state *x) 291 { 292 struct esp_data *esp = x->data; 293 294 if (!esp) 295 return; 296 297 crypto_free_tfm(esp->conf.tfm); 298 esp->conf.tfm = NULL; 299 kfree(esp->conf.ivec); 300 esp->conf.ivec = NULL; 301 crypto_free_tfm(esp->auth.tfm); 302 esp->auth.tfm = NULL; 303 kfree(esp->auth.work_icv); 304 esp->auth.work_icv = NULL; 305 kfree(esp); 306 } 307 308 static int esp_init_state(struct xfrm_state *x) 309 { 310 struct esp_data *esp = NULL; 311 312 /* null auth and encryption can have zero length keys */ 313 if (x->aalg) { 314 if (x->aalg->alg_key_len > 512) 315 goto error; 316 } 317 if (x->ealg == NULL) 318 goto error; 319 320 esp = kmalloc(sizeof(*esp), GFP_KERNEL); 321 if (esp == NULL) 322 return -ENOMEM; 323 324 memset(esp, 0, sizeof(*esp)); 325 326 if (x->aalg) { 327 struct xfrm_algo_desc *aalg_desc; 328 329 esp->auth.key = x->aalg->alg_key; 330 esp->auth.key_len = (x->aalg->alg_key_len+7)/8; 331 esp->auth.tfm = crypto_alloc_tfm(x->aalg->alg_name, 0); 332 if (esp->auth.tfm == NULL) 333 goto error; 334 esp->auth.icv = esp_hmac_digest; 335 336 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 337 BUG_ON(!aalg_desc); 338 339 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 340 crypto_tfm_alg_digestsize(esp->auth.tfm)) { 341 NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n", 342 x->aalg->alg_name, 343 crypto_tfm_alg_digestsize(esp->auth.tfm), 344 aalg_desc->uinfo.auth.icv_fullbits/8); 345 goto error; 346 } 347 348 esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; 349 esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8; 350 351 esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL); 352 if (!esp->auth.work_icv) 353 goto error; 354 } 355 esp->conf.key = x->ealg->alg_key; 356 esp->conf.key_len = (x->ealg->alg_key_len+7)/8; 357 if (x->props.ealgo == SADB_EALG_NULL) 358 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_ECB); 359 else 360 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_CBC); 361 if (esp->conf.tfm == NULL) 362 goto error; 363 esp->conf.ivlen = crypto_tfm_alg_ivsize(esp->conf.tfm); 364 esp->conf.padlen = 0; 365 if (esp->conf.ivlen) { 366 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL); 367 if (unlikely(esp->conf.ivec == NULL)) 368 goto error; 369 get_random_bytes(esp->conf.ivec, esp->conf.ivlen); 370 } 371 if (crypto_cipher_setkey(esp->conf.tfm, esp->conf.key, esp->conf.key_len)) 372 goto error; 373 x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen; 374 if (x->props.mode) 375 x->props.header_len += sizeof(struct iphdr); 376 if (x->encap) { 377 struct xfrm_encap_tmpl *encap = x->encap; 378 379 switch (encap->encap_type) { 380 default: 381 goto error; 382 case UDP_ENCAP_ESPINUDP: 383 x->props.header_len += sizeof(struct udphdr); 384 break; 385 case UDP_ENCAP_ESPINUDP_NON_IKE: 386 x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32); 387 break; 388 } 389 } 390 x->data = esp; 391 x->props.trailer_len = esp4_get_max_size(x, 0) - x->props.header_len; 392 return 0; 393 394 error: 395 x->data = esp; 396 esp_destroy(x); 397 x->data = NULL; 398 return -EINVAL; 399 } 400 401 static struct xfrm_type esp_type = 402 { 403 .description = "ESP4", 404 .owner = THIS_MODULE, 405 .proto = IPPROTO_ESP, 406 .init_state = esp_init_state, 407 .destructor = esp_destroy, 408 .get_max_size = esp4_get_max_size, 409 .input = esp_input, 410 .output = esp_output 411 }; 412 413 static struct net_protocol esp4_protocol = { 414 .handler = xfrm4_rcv, 415 .err_handler = esp4_err, 416 .no_policy = 1, 417 }; 418 419 static int __init esp4_init(void) 420 { 421 if (xfrm_register_type(&esp_type, AF_INET) < 0) { 422 printk(KERN_INFO "ip esp init: can't add xfrm type\n"); 423 return -EAGAIN; 424 } 425 if (inet_add_protocol(&esp4_protocol, IPPROTO_ESP) < 0) { 426 printk(KERN_INFO "ip esp init: can't add protocol\n"); 427 xfrm_unregister_type(&esp_type, AF_INET); 428 return -EAGAIN; 429 } 430 return 0; 431 } 432 433 static void __exit esp4_fini(void) 434 { 435 if (inet_del_protocol(&esp4_protocol, IPPROTO_ESP) < 0) 436 printk(KERN_INFO "ip esp close: can't remove protocol\n"); 437 if (xfrm_unregister_type(&esp_type, AF_INET) < 0) 438 printk(KERN_INFO "ip esp close: can't remove xfrm type\n"); 439 } 440 441 module_init(esp4_init); 442 module_exit(esp4_fini); 443 MODULE_LICENSE("GPL"); 444