1 /* 2 * Copyright (C)2002 USAGI/WIDE Project 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License as published by 6 * the Free Software Foundation; either version 2 of the License, or 7 * (at your option) any later version. 8 * 9 * This program is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * GNU General Public License for more details. 13 * 14 * You should have received a copy of the GNU General Public License 15 * along with this program; if not, write to the Free Software 16 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 17 * 18 * Authors 19 * 20 * Mitsuru KANDA @USAGI : IPv6 Support 21 * Kazunori MIYAZAWA @USAGI : 22 * Kunihiro Ishiguro <kunihiro@ipinfusion.com> 23 * 24 * This file is derived from net/ipv4/esp.c 25 */ 26 27 #include <linux/err.h> 28 #include <linux/module.h> 29 #include <net/ip.h> 30 #include <net/xfrm.h> 31 #include <net/esp.h> 32 #include <linux/scatterlist.h> 33 #include <linux/crypto.h> 34 #include <linux/kernel.h> 35 #include <linux/pfkeyv2.h> 36 #include <linux/random.h> 37 #include <linux/spinlock.h> 38 #include <net/icmp.h> 39 #include <net/ipv6.h> 40 #include <net/protocol.h> 41 #include <linux/icmpv6.h> 42 43 static int esp6_output(struct xfrm_state *x, struct sk_buff *skb) 44 { 45 int err; 46 struct ip_esp_hdr *esph; 47 struct crypto_blkcipher *tfm; 48 struct blkcipher_desc desc; 49 struct sk_buff *trailer; 50 int blksize; 51 int clen; 52 int alen; 53 int nfrags; 54 u8 *tail; 55 struct esp_data *esp = x->data; 56 57 /* skb is pure payload to encrypt */ 58 err = -ENOMEM; 59 60 /* Round to block size */ 61 clen = skb->len; 62 63 alen = esp->auth.icv_trunc_len; 64 tfm = esp->conf.tfm; 65 desc.tfm = tfm; 66 desc.flags = 0; 67 blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4); 68 clen = ALIGN(clen + 2, blksize); 69 if (esp->conf.padlen) 70 clen = ALIGN(clen, esp->conf.padlen); 71 72 if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0) { 73 goto error; 74 } 75 76 /* Fill padding... */ 77 tail = skb_tail_pointer(trailer); 78 do { 79 int i; 80 for (i=0; i<clen-skb->len - 2; i++) 81 tail[i] = i + 1; 82 } while (0); 83 tail[clen-skb->len - 2] = (clen - skb->len) - 2; 84 pskb_put(skb, trailer, clen - skb->len); 85 86 skb_push(skb, -skb_network_offset(skb)); 87 esph = ip_esp_hdr(skb); 88 *(skb_tail_pointer(trailer) - 1) = *skb_mac_header(skb); 89 *skb_mac_header(skb) = IPPROTO_ESP; 90 91 esph->spi = x->id.spi; 92 esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq); 93 94 spin_lock_bh(&x->lock); 95 96 if (esp->conf.ivlen) { 97 if (unlikely(!esp->conf.ivinitted)) { 98 get_random_bytes(esp->conf.ivec, esp->conf.ivlen); 99 esp->conf.ivinitted = 1; 100 } 101 crypto_blkcipher_set_iv(tfm, esp->conf.ivec, esp->conf.ivlen); 102 } 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 unlock; 111 } 112 sg_init_table(sg, nfrags); 113 skb_to_sgvec(skb, sg, 114 esph->enc_data + 115 esp->conf.ivlen - 116 skb->data, clen); 117 err = crypto_blkcipher_encrypt(&desc, sg, sg, clen); 118 if (unlikely(sg != &esp->sgbuf[0])) 119 kfree(sg); 120 } while (0); 121 122 if (unlikely(err)) 123 goto unlock; 124 125 if (esp->conf.ivlen) { 126 memcpy(esph->enc_data, esp->conf.ivec, esp->conf.ivlen); 127 crypto_blkcipher_get_iv(tfm, esp->conf.ivec, esp->conf.ivlen); 128 } 129 130 if (esp->auth.icv_full_len) { 131 err = esp_mac_digest(esp, skb, (u8 *)esph - skb->data, 132 sizeof(*esph) + esp->conf.ivlen + clen); 133 memcpy(pskb_put(skb, trailer, alen), esp->auth.work_icv, alen); 134 } 135 136 unlock: 137 spin_unlock_bh(&x->lock); 138 139 error: 140 return err; 141 } 142 143 static int esp6_input(struct xfrm_state *x, struct sk_buff *skb) 144 { 145 struct ipv6hdr *iph; 146 struct ip_esp_hdr *esph; 147 struct esp_data *esp = x->data; 148 struct crypto_blkcipher *tfm = esp->conf.tfm; 149 struct blkcipher_desc desc = { .tfm = tfm }; 150 struct sk_buff *trailer; 151 int blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4); 152 int alen = esp->auth.icv_trunc_len; 153 int elen = skb->len - sizeof(*esph) - esp->conf.ivlen - alen; 154 int hdr_len = skb_network_header_len(skb); 155 int nfrags; 156 int ret = 0; 157 158 if (!pskb_may_pull(skb, sizeof(*esph))) { 159 ret = -EINVAL; 160 goto out; 161 } 162 163 if (elen <= 0 || (elen & (blksize-1))) { 164 ret = -EINVAL; 165 goto out; 166 } 167 168 /* If integrity check is required, do this. */ 169 if (esp->auth.icv_full_len) { 170 u8 sum[alen]; 171 172 ret = esp_mac_digest(esp, skb, 0, skb->len - alen); 173 if (ret) 174 goto out; 175 176 if (skb_copy_bits(skb, skb->len - alen, sum, alen)) 177 BUG(); 178 179 if (unlikely(memcmp(esp->auth.work_icv, sum, alen))) { 180 x->stats.integrity_failed++; 181 ret = -EINVAL; 182 goto out; 183 } 184 } 185 186 if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) { 187 ret = -EINVAL; 188 goto out; 189 } 190 191 skb->ip_summed = CHECKSUM_NONE; 192 193 esph = (struct ip_esp_hdr *)skb->data; 194 iph = ipv6_hdr(skb); 195 196 /* Get ivec. This can be wrong, check against another impls. */ 197 if (esp->conf.ivlen) 198 crypto_blkcipher_set_iv(tfm, esph->enc_data, esp->conf.ivlen); 199 200 { 201 u8 nexthdr[2]; 202 struct scatterlist *sg = &esp->sgbuf[0]; 203 u8 padlen; 204 205 if (unlikely(nfrags > ESP_NUM_FAST_SG)) { 206 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); 207 if (!sg) { 208 ret = -ENOMEM; 209 goto out; 210 } 211 } 212 sg_init_table(sg, nfrags); 213 skb_to_sgvec(skb, sg, 214 sizeof(*esph) + esp->conf.ivlen, 215 elen); 216 ret = crypto_blkcipher_decrypt(&desc, sg, sg, elen); 217 if (unlikely(sg != &esp->sgbuf[0])) 218 kfree(sg); 219 if (unlikely(ret)) 220 goto out; 221 222 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2)) 223 BUG(); 224 225 padlen = nexthdr[0]; 226 if (padlen+2 >= elen) { 227 LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage padlen=%d, elen=%d\n", padlen+2, elen); 228 ret = -EINVAL; 229 goto out; 230 } 231 /* ... check padding bits here. Silly. :-) */ 232 233 pskb_trim(skb, skb->len - alen - padlen - 2); 234 ret = nexthdr[1]; 235 } 236 237 __skb_pull(skb, sizeof(*esph) + esp->conf.ivlen); 238 skb_set_transport_header(skb, -hdr_len); 239 out: 240 return ret; 241 } 242 243 static u32 esp6_get_mtu(struct xfrm_state *x, int mtu) 244 { 245 struct esp_data *esp = x->data; 246 u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4); 247 u32 align = max_t(u32, blksize, esp->conf.padlen); 248 u32 rem; 249 250 mtu -= x->props.header_len + esp->auth.icv_trunc_len; 251 rem = mtu & (align - 1); 252 mtu &= ~(align - 1); 253 254 if (x->props.mode != XFRM_MODE_TUNNEL) { 255 u32 padsize = ((blksize - 1) & 7) + 1; 256 mtu -= blksize - padsize; 257 mtu += min_t(u32, blksize - padsize, rem); 258 } 259 260 return mtu - 2; 261 } 262 263 static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 264 int type, int code, int offset, __be32 info) 265 { 266 struct ipv6hdr *iph = (struct ipv6hdr*)skb->data; 267 struct ip_esp_hdr *esph = (struct ip_esp_hdr *)(skb->data + offset); 268 struct xfrm_state *x; 269 270 if (type != ICMPV6_DEST_UNREACH && 271 type != ICMPV6_PKT_TOOBIG) 272 return; 273 274 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET6); 275 if (!x) 276 return; 277 printk(KERN_DEBUG "pmtu discovery on SA ESP/%08x/" NIP6_FMT "\n", 278 ntohl(esph->spi), NIP6(iph->daddr)); 279 xfrm_state_put(x); 280 } 281 282 static void esp6_destroy(struct xfrm_state *x) 283 { 284 struct esp_data *esp = x->data; 285 286 if (!esp) 287 return; 288 289 crypto_free_blkcipher(esp->conf.tfm); 290 esp->conf.tfm = NULL; 291 kfree(esp->conf.ivec); 292 esp->conf.ivec = NULL; 293 crypto_free_hash(esp->auth.tfm); 294 esp->auth.tfm = NULL; 295 kfree(esp->auth.work_icv); 296 esp->auth.work_icv = NULL; 297 kfree(esp); 298 } 299 300 static int esp6_init_state(struct xfrm_state *x) 301 { 302 struct esp_data *esp = NULL; 303 struct crypto_blkcipher *tfm; 304 305 if (x->ealg == NULL) 306 goto error; 307 308 if (x->encap) 309 goto error; 310 311 esp = kzalloc(sizeof(*esp), GFP_KERNEL); 312 if (esp == NULL) 313 return -ENOMEM; 314 315 if (x->aalg) { 316 struct xfrm_algo_desc *aalg_desc; 317 struct crypto_hash *hash; 318 319 hash = crypto_alloc_hash(x->aalg->alg_name, 0, 320 CRYPTO_ALG_ASYNC); 321 if (IS_ERR(hash)) 322 goto error; 323 324 esp->auth.tfm = hash; 325 if (crypto_hash_setkey(hash, x->aalg->alg_key, 326 (x->aalg->alg_key_len + 7) / 8)) 327 goto error; 328 329 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 330 BUG_ON(!aalg_desc); 331 332 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 333 crypto_hash_digestsize(hash)) { 334 NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n", 335 x->aalg->alg_name, 336 crypto_hash_digestsize(hash), 337 aalg_desc->uinfo.auth.icv_fullbits/8); 338 goto error; 339 } 340 341 esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; 342 esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8; 343 344 esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL); 345 if (!esp->auth.work_icv) 346 goto error; 347 } 348 tfm = crypto_alloc_blkcipher(x->ealg->alg_name, 0, CRYPTO_ALG_ASYNC); 349 if (IS_ERR(tfm)) 350 goto error; 351 esp->conf.tfm = tfm; 352 esp->conf.ivlen = crypto_blkcipher_ivsize(tfm); 353 esp->conf.padlen = 0; 354 if (esp->conf.ivlen) { 355 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL); 356 if (unlikely(esp->conf.ivec == NULL)) 357 goto error; 358 esp->conf.ivinitted = 0; 359 } 360 if (crypto_blkcipher_setkey(tfm, x->ealg->alg_key, 361 (x->ealg->alg_key_len + 7) / 8)) 362 goto error; 363 x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen; 364 switch (x->props.mode) { 365 case XFRM_MODE_BEET: 366 case XFRM_MODE_TRANSPORT: 367 break; 368 case XFRM_MODE_TUNNEL: 369 x->props.header_len += sizeof(struct ipv6hdr); 370 break; 371 default: 372 goto error; 373 } 374 x->data = esp; 375 return 0; 376 377 error: 378 x->data = esp; 379 esp6_destroy(x); 380 x->data = NULL; 381 return -EINVAL; 382 } 383 384 static struct xfrm_type esp6_type = 385 { 386 .description = "ESP6", 387 .owner = THIS_MODULE, 388 .proto = IPPROTO_ESP, 389 .flags = XFRM_TYPE_REPLAY_PROT, 390 .init_state = esp6_init_state, 391 .destructor = esp6_destroy, 392 .get_mtu = esp6_get_mtu, 393 .input = esp6_input, 394 .output = esp6_output, 395 .hdr_offset = xfrm6_find_1stfragopt, 396 }; 397 398 static struct inet6_protocol esp6_protocol = { 399 .handler = xfrm6_rcv, 400 .err_handler = esp6_err, 401 .flags = INET6_PROTO_NOPOLICY, 402 }; 403 404 static int __init esp6_init(void) 405 { 406 if (xfrm_register_type(&esp6_type, AF_INET6) < 0) { 407 printk(KERN_INFO "ipv6 esp init: can't add xfrm type\n"); 408 return -EAGAIN; 409 } 410 if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) { 411 printk(KERN_INFO "ipv6 esp init: can't add protocol\n"); 412 xfrm_unregister_type(&esp6_type, AF_INET6); 413 return -EAGAIN; 414 } 415 416 return 0; 417 } 418 419 static void __exit esp6_fini(void) 420 { 421 if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0) 422 printk(KERN_INFO "ipv6 esp close: can't remove protocol\n"); 423 if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0) 424 printk(KERN_INFO "ipv6 esp close: can't remove xfrm type\n"); 425 } 426 427 module_init(esp6_init); 428 module_exit(esp6_fini); 429 430 MODULE_LICENSE("GPL"); 431 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ESP); 432