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 <asm/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 skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen); 113 err = crypto_blkcipher_encrypt(&desc, sg, sg, clen); 114 if (unlikely(sg != &esp->sgbuf[0])) 115 kfree(sg); 116 } while (0); 117 118 if (unlikely(err)) 119 goto unlock; 120 121 if (esp->conf.ivlen) { 122 memcpy(esph->enc_data, esp->conf.ivec, esp->conf.ivlen); 123 crypto_blkcipher_get_iv(tfm, esp->conf.ivec, esp->conf.ivlen); 124 } 125 126 if (esp->auth.icv_full_len) { 127 err = esp_mac_digest(esp, skb, (u8 *)esph - skb->data, 128 sizeof(*esph) + esp->conf.ivlen + clen); 129 memcpy(pskb_put(skb, trailer, alen), esp->auth.work_icv, alen); 130 } 131 132 unlock: 133 spin_unlock_bh(&x->lock); 134 135 error: 136 return err; 137 } 138 139 static int esp6_input(struct xfrm_state *x, struct sk_buff *skb) 140 { 141 struct ipv6hdr *iph; 142 struct ip_esp_hdr *esph; 143 struct esp_data *esp = x->data; 144 struct crypto_blkcipher *tfm = esp->conf.tfm; 145 struct blkcipher_desc desc = { .tfm = tfm }; 146 struct sk_buff *trailer; 147 int blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4); 148 int alen = esp->auth.icv_trunc_len; 149 int elen = skb->len - sizeof(*esph) - esp->conf.ivlen - alen; 150 int hdr_len = skb_network_header_len(skb); 151 int nfrags; 152 int ret = 0; 153 154 if (!pskb_may_pull(skb, sizeof(*esph))) { 155 ret = -EINVAL; 156 goto out; 157 } 158 159 if (elen <= 0 || (elen & (blksize-1))) { 160 ret = -EINVAL; 161 goto out; 162 } 163 164 /* If integrity check is required, do this. */ 165 if (esp->auth.icv_full_len) { 166 u8 sum[alen]; 167 168 ret = esp_mac_digest(esp, skb, 0, skb->len - alen); 169 if (ret) 170 goto out; 171 172 if (skb_copy_bits(skb, skb->len - alen, sum, alen)) 173 BUG(); 174 175 if (unlikely(memcmp(esp->auth.work_icv, sum, alen))) { 176 x->stats.integrity_failed++; 177 ret = -EINVAL; 178 goto out; 179 } 180 } 181 182 if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) { 183 ret = -EINVAL; 184 goto out; 185 } 186 187 skb->ip_summed = CHECKSUM_NONE; 188 189 esph = (struct ip_esp_hdr *)skb->data; 190 iph = ipv6_hdr(skb); 191 192 /* Get ivec. This can be wrong, check against another impls. */ 193 if (esp->conf.ivlen) 194 crypto_blkcipher_set_iv(tfm, esph->enc_data, esp->conf.ivlen); 195 196 { 197 u8 nexthdr[2]; 198 struct scatterlist *sg = &esp->sgbuf[0]; 199 u8 padlen; 200 201 if (unlikely(nfrags > ESP_NUM_FAST_SG)) { 202 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); 203 if (!sg) { 204 ret = -ENOMEM; 205 goto out; 206 } 207 } 208 skb_to_sgvec(skb, sg, sizeof(*esph) + esp->conf.ivlen, elen); 209 ret = crypto_blkcipher_decrypt(&desc, sg, sg, elen); 210 if (unlikely(sg != &esp->sgbuf[0])) 211 kfree(sg); 212 if (unlikely(ret)) 213 goto out; 214 215 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2)) 216 BUG(); 217 218 padlen = nexthdr[0]; 219 if (padlen+2 >= elen) { 220 LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage padlen=%d, elen=%d\n", padlen+2, elen); 221 ret = -EINVAL; 222 goto out; 223 } 224 /* ... check padding bits here. Silly. :-) */ 225 226 pskb_trim(skb, skb->len - alen - padlen - 2); 227 ret = nexthdr[1]; 228 } 229 230 __skb_pull(skb, sizeof(*esph) + esp->conf.ivlen); 231 skb_set_transport_header(skb, -hdr_len); 232 out: 233 return ret; 234 } 235 236 static u32 esp6_get_mtu(struct xfrm_state *x, int mtu) 237 { 238 struct esp_data *esp = x->data; 239 u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4); 240 u32 align = max_t(u32, blksize, esp->conf.padlen); 241 u32 rem; 242 243 mtu -= x->props.header_len + esp->auth.icv_trunc_len; 244 rem = mtu & (align - 1); 245 mtu &= ~(align - 1); 246 247 if (x->props.mode != XFRM_MODE_TUNNEL) { 248 u32 padsize = ((blksize - 1) & 7) + 1; 249 mtu -= blksize - padsize; 250 mtu += min_t(u32, blksize - padsize, rem); 251 } 252 253 return mtu - 2; 254 } 255 256 static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 257 int type, int code, int offset, __be32 info) 258 { 259 struct ipv6hdr *iph = (struct ipv6hdr*)skb->data; 260 struct ip_esp_hdr *esph = (struct ip_esp_hdr *)(skb->data + offset); 261 struct xfrm_state *x; 262 263 if (type != ICMPV6_DEST_UNREACH && 264 type != ICMPV6_PKT_TOOBIG) 265 return; 266 267 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET6); 268 if (!x) 269 return; 270 printk(KERN_DEBUG "pmtu discovery on SA ESP/%08x/" NIP6_FMT "\n", 271 ntohl(esph->spi), NIP6(iph->daddr)); 272 xfrm_state_put(x); 273 } 274 275 static void esp6_destroy(struct xfrm_state *x) 276 { 277 struct esp_data *esp = x->data; 278 279 if (!esp) 280 return; 281 282 crypto_free_blkcipher(esp->conf.tfm); 283 esp->conf.tfm = NULL; 284 kfree(esp->conf.ivec); 285 esp->conf.ivec = NULL; 286 crypto_free_hash(esp->auth.tfm); 287 esp->auth.tfm = NULL; 288 kfree(esp->auth.work_icv); 289 esp->auth.work_icv = NULL; 290 kfree(esp); 291 } 292 293 static int esp6_init_state(struct xfrm_state *x) 294 { 295 struct esp_data *esp = NULL; 296 struct crypto_blkcipher *tfm; 297 298 if (x->ealg == NULL) 299 goto error; 300 301 if (x->encap) 302 goto error; 303 304 esp = kzalloc(sizeof(*esp), GFP_KERNEL); 305 if (esp == NULL) 306 return -ENOMEM; 307 308 if (x->aalg) { 309 struct xfrm_algo_desc *aalg_desc; 310 struct crypto_hash *hash; 311 312 hash = crypto_alloc_hash(x->aalg->alg_name, 0, 313 CRYPTO_ALG_ASYNC); 314 if (IS_ERR(hash)) 315 goto error; 316 317 esp->auth.tfm = hash; 318 if (crypto_hash_setkey(hash, x->aalg->alg_key, 319 (x->aalg->alg_key_len + 7) / 8)) 320 goto error; 321 322 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 323 BUG_ON(!aalg_desc); 324 325 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 326 crypto_hash_digestsize(hash)) { 327 NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n", 328 x->aalg->alg_name, 329 crypto_hash_digestsize(hash), 330 aalg_desc->uinfo.auth.icv_fullbits/8); 331 goto error; 332 } 333 334 esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; 335 esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8; 336 337 esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL); 338 if (!esp->auth.work_icv) 339 goto error; 340 } 341 tfm = crypto_alloc_blkcipher(x->ealg->alg_name, 0, CRYPTO_ALG_ASYNC); 342 if (IS_ERR(tfm)) 343 goto error; 344 esp->conf.tfm = tfm; 345 esp->conf.ivlen = crypto_blkcipher_ivsize(tfm); 346 esp->conf.padlen = 0; 347 if (esp->conf.ivlen) { 348 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL); 349 if (unlikely(esp->conf.ivec == NULL)) 350 goto error; 351 esp->conf.ivinitted = 0; 352 } 353 if (crypto_blkcipher_setkey(tfm, x->ealg->alg_key, 354 (x->ealg->alg_key_len + 7) / 8)) 355 goto error; 356 x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen; 357 switch (x->props.mode) { 358 case XFRM_MODE_BEET: 359 case XFRM_MODE_TRANSPORT: 360 break; 361 case XFRM_MODE_TUNNEL: 362 x->props.header_len += sizeof(struct ipv6hdr); 363 default: 364 goto error; 365 } 366 x->data = esp; 367 return 0; 368 369 error: 370 x->data = esp; 371 esp6_destroy(x); 372 x->data = NULL; 373 return -EINVAL; 374 } 375 376 static struct xfrm_type esp6_type = 377 { 378 .description = "ESP6", 379 .owner = THIS_MODULE, 380 .proto = IPPROTO_ESP, 381 .flags = XFRM_TYPE_REPLAY_PROT, 382 .init_state = esp6_init_state, 383 .destructor = esp6_destroy, 384 .get_mtu = esp6_get_mtu, 385 .input = esp6_input, 386 .output = esp6_output, 387 .hdr_offset = xfrm6_find_1stfragopt, 388 }; 389 390 static struct inet6_protocol esp6_protocol = { 391 .handler = xfrm6_rcv, 392 .err_handler = esp6_err, 393 .flags = INET6_PROTO_NOPOLICY, 394 }; 395 396 static int __init esp6_init(void) 397 { 398 if (xfrm_register_type(&esp6_type, AF_INET6) < 0) { 399 printk(KERN_INFO "ipv6 esp init: can't add xfrm type\n"); 400 return -EAGAIN; 401 } 402 if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) { 403 printk(KERN_INFO "ipv6 esp init: can't add protocol\n"); 404 xfrm_unregister_type(&esp6_type, AF_INET6); 405 return -EAGAIN; 406 } 407 408 return 0; 409 } 410 411 static void __exit esp6_fini(void) 412 { 413 if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0) 414 printk(KERN_INFO "ipv6 esp close: can't remove protocol\n"); 415 if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0) 416 printk(KERN_INFO "ipv6 esp close: can't remove xfrm type\n"); 417 } 418 419 module_init(esp6_init); 420 module_exit(esp6_fini); 421 422 MODULE_LICENSE("GPL"); 423 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ESP); 424