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 <net/icmp.h> 38 #include <net/ipv6.h> 39 #include <net/protocol.h> 40 #include <linux/icmpv6.h> 41 42 static int esp6_output(struct xfrm_state *x, struct sk_buff *skb) 43 { 44 int err; 45 struct ipv6hdr *top_iph; 46 struct ipv6_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 int hdr_len = (skb_transport_offset(skb) + 57 sizeof(*esph) + esp->conf.ivlen); 58 59 /* Strip IP+ESP header. */ 60 __skb_pull(skb, hdr_len); 61 62 /* Now skb is pure payload to encrypt */ 63 err = -ENOMEM; 64 65 /* Round to block size */ 66 clen = skb->len; 67 68 alen = esp->auth.icv_trunc_len; 69 tfm = esp->conf.tfm; 70 desc.tfm = tfm; 71 desc.flags = 0; 72 blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4); 73 clen = ALIGN(clen + 2, blksize); 74 if (esp->conf.padlen) 75 clen = ALIGN(clen, esp->conf.padlen); 76 77 if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0) { 78 goto error; 79 } 80 81 /* Fill padding... */ 82 tail = skb_tail_pointer(trailer); 83 do { 84 int i; 85 for (i=0; i<clen-skb->len - 2; i++) 86 tail[i] = i + 1; 87 } while (0); 88 tail[clen-skb->len - 2] = (clen - skb->len) - 2; 89 pskb_put(skb, trailer, clen - skb->len); 90 91 top_iph = (struct ipv6hdr *)__skb_push(skb, hdr_len); 92 esph = (struct ipv6_esp_hdr *)skb_transport_header(skb); 93 top_iph->payload_len = htons(skb->len + alen - sizeof(*top_iph)); 94 *(skb_tail_pointer(trailer) - 1) = *skb_network_header(skb); 95 *skb_network_header(skb) = IPPROTO_ESP; 96 97 esph->spi = x->id.spi; 98 esph->seq_no = htonl(++x->replay.oseq); 99 xfrm_aevent_doreplay(x); 100 101 if (esp->conf.ivlen) { 102 if (unlikely(!esp->conf.ivinitted)) { 103 get_random_bytes(esp->conf.ivec, esp->conf.ivlen); 104 esp->conf.ivinitted = 1; 105 } 106 crypto_blkcipher_set_iv(tfm, esp->conf.ivec, esp->conf.ivlen); 107 } 108 109 do { 110 struct scatterlist *sg = &esp->sgbuf[0]; 111 112 if (unlikely(nfrags > ESP_NUM_FAST_SG)) { 113 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); 114 if (!sg) 115 goto error; 116 } 117 skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen); 118 err = crypto_blkcipher_encrypt(&desc, sg, sg, clen); 119 if (unlikely(sg != &esp->sgbuf[0])) 120 kfree(sg); 121 } while (0); 122 123 if (unlikely(err)) 124 goto error; 125 126 if (esp->conf.ivlen) { 127 memcpy(esph->enc_data, esp->conf.ivec, esp->conf.ivlen); 128 crypto_blkcipher_get_iv(tfm, esp->conf.ivec, esp->conf.ivlen); 129 } 130 131 if (esp->auth.icv_full_len) { 132 err = esp_mac_digest(esp, skb, (u8 *)esph - skb->data, 133 sizeof(*esph) + esp->conf.ivlen + clen); 134 memcpy(pskb_put(skb, trailer, alen), esp->auth.work_icv, alen); 135 } 136 137 error: 138 return err; 139 } 140 141 static int esp6_input(struct xfrm_state *x, struct sk_buff *skb) 142 { 143 struct ipv6hdr *iph; 144 struct ipv6_esp_hdr *esph; 145 struct esp_data *esp = x->data; 146 struct crypto_blkcipher *tfm = esp->conf.tfm; 147 struct blkcipher_desc desc = { .tfm = tfm }; 148 struct sk_buff *trailer; 149 int blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4); 150 int alen = esp->auth.icv_trunc_len; 151 int elen = skb->len - sizeof(struct ipv6_esp_hdr) - esp->conf.ivlen - alen; 152 int hdr_len = skb_network_header_len(skb); 153 int nfrags; 154 int ret = 0; 155 156 if (!pskb_may_pull(skb, sizeof(struct ipv6_esp_hdr))) { 157 ret = -EINVAL; 158 goto out; 159 } 160 161 if (elen <= 0 || (elen & (blksize-1))) { 162 ret = -EINVAL; 163 goto out; 164 } 165 166 /* If integrity check is required, do this. */ 167 if (esp->auth.icv_full_len) { 168 u8 sum[alen]; 169 170 ret = esp_mac_digest(esp, skb, 0, skb->len - alen); 171 if (ret) 172 goto out; 173 174 if (skb_copy_bits(skb, skb->len - alen, sum, alen)) 175 BUG(); 176 177 if (unlikely(memcmp(esp->auth.work_icv, sum, alen))) { 178 x->stats.integrity_failed++; 179 ret = -EINVAL; 180 goto out; 181 } 182 } 183 184 if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) { 185 ret = -EINVAL; 186 goto out; 187 } 188 189 skb->ip_summed = CHECKSUM_NONE; 190 191 esph = (struct ipv6_esp_hdr*)skb->data; 192 iph = ipv6_hdr(skb); 193 194 /* Get ivec. This can be wrong, check against another impls. */ 195 if (esp->conf.ivlen) 196 crypto_blkcipher_set_iv(tfm, esph->enc_data, esp->conf.ivlen); 197 198 { 199 u8 nexthdr[2]; 200 struct scatterlist *sg = &esp->sgbuf[0]; 201 u8 padlen; 202 203 if (unlikely(nfrags > ESP_NUM_FAST_SG)) { 204 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); 205 if (!sg) { 206 ret = -ENOMEM; 207 goto out; 208 } 209 } 210 skb_to_sgvec(skb, sg, sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen, elen); 211 ret = crypto_blkcipher_decrypt(&desc, sg, sg, elen); 212 if (unlikely(sg != &esp->sgbuf[0])) 213 kfree(sg); 214 if (unlikely(ret)) 215 goto out; 216 217 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2)) 218 BUG(); 219 220 padlen = nexthdr[0]; 221 if (padlen+2 >= elen) { 222 LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage padlen=%d, elen=%d\n", padlen+2, elen); 223 ret = -EINVAL; 224 goto out; 225 } 226 /* ... check padding bits here. Silly. :-) */ 227 228 pskb_trim(skb, skb->len - alen - padlen - 2); 229 ret = nexthdr[1]; 230 } 231 232 __skb_pull(skb, sizeof(*esph) + esp->conf.ivlen); 233 skb_set_transport_header(skb, -hdr_len); 234 out: 235 return ret; 236 } 237 238 static u32 esp6_get_mtu(struct xfrm_state *x, int mtu) 239 { 240 struct esp_data *esp = x->data; 241 u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4); 242 u32 align = max_t(u32, blksize, esp->conf.padlen); 243 u32 rem; 244 245 mtu -= x->props.header_len + esp->auth.icv_trunc_len; 246 rem = mtu & (align - 1); 247 mtu &= ~(align - 1); 248 249 if (x->props.mode != XFRM_MODE_TUNNEL) { 250 u32 padsize = ((blksize - 1) & 7) + 1; 251 mtu -= blksize - padsize; 252 mtu += min_t(u32, blksize - padsize, rem); 253 } 254 255 return mtu - 2; 256 } 257 258 static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 259 int type, int code, int offset, __be32 info) 260 { 261 struct ipv6hdr *iph = (struct ipv6hdr*)skb->data; 262 struct ipv6_esp_hdr *esph = (struct ipv6_esp_hdr*)(skb->data+offset); 263 struct xfrm_state *x; 264 265 if (type != ICMPV6_DEST_UNREACH && 266 type != ICMPV6_PKT_TOOBIG) 267 return; 268 269 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET6); 270 if (!x) 271 return; 272 printk(KERN_DEBUG "pmtu discovery on SA ESP/%08x/" NIP6_FMT "\n", 273 ntohl(esph->spi), NIP6(iph->daddr)); 274 xfrm_state_put(x); 275 } 276 277 static void esp6_destroy(struct xfrm_state *x) 278 { 279 struct esp_data *esp = x->data; 280 281 if (!esp) 282 return; 283 284 crypto_free_blkcipher(esp->conf.tfm); 285 esp->conf.tfm = NULL; 286 kfree(esp->conf.ivec); 287 esp->conf.ivec = NULL; 288 crypto_free_hash(esp->auth.tfm); 289 esp->auth.tfm = NULL; 290 kfree(esp->auth.work_icv); 291 esp->auth.work_icv = NULL; 292 kfree(esp); 293 } 294 295 static int esp6_init_state(struct xfrm_state *x) 296 { 297 struct esp_data *esp = NULL; 298 struct crypto_blkcipher *tfm; 299 300 /* null auth and encryption can have zero length keys */ 301 if (x->aalg) { 302 if (x->aalg->alg_key_len > 512) 303 goto error; 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 esp->auth.key = x->aalg->alg_key; 320 esp->auth.key_len = (x->aalg->alg_key_len+7)/8; 321 hash = crypto_alloc_hash(x->aalg->alg_name, 0, 322 CRYPTO_ALG_ASYNC); 323 if (IS_ERR(hash)) 324 goto error; 325 326 esp->auth.tfm = hash; 327 if (crypto_hash_setkey(hash, esp->auth.key, esp->auth.key_len)) 328 goto error; 329 330 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 331 BUG_ON(!aalg_desc); 332 333 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 334 crypto_hash_digestsize(hash)) { 335 NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n", 336 x->aalg->alg_name, 337 crypto_hash_digestsize(hash), 338 aalg_desc->uinfo.auth.icv_fullbits/8); 339 goto error; 340 } 341 342 esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; 343 esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8; 344 345 esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL); 346 if (!esp->auth.work_icv) 347 goto error; 348 } 349 esp->conf.key = x->ealg->alg_key; 350 esp->conf.key_len = (x->ealg->alg_key_len+7)/8; 351 tfm = crypto_alloc_blkcipher(x->ealg->alg_name, 0, CRYPTO_ALG_ASYNC); 352 if (IS_ERR(tfm)) 353 goto error; 354 esp->conf.tfm = tfm; 355 esp->conf.ivlen = crypto_blkcipher_ivsize(tfm); 356 esp->conf.padlen = 0; 357 if (esp->conf.ivlen) { 358 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL); 359 if (unlikely(esp->conf.ivec == NULL)) 360 goto error; 361 esp->conf.ivinitted = 0; 362 } 363 if (crypto_blkcipher_setkey(tfm, esp->conf.key, esp->conf.key_len)) 364 goto error; 365 x->props.header_len = sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen; 366 if (x->props.mode == XFRM_MODE_TUNNEL) 367 x->props.header_len += sizeof(struct ipv6hdr); 368 x->data = esp; 369 return 0; 370 371 error: 372 x->data = esp; 373 esp6_destroy(x); 374 x->data = NULL; 375 return -EINVAL; 376 } 377 378 static struct xfrm_type esp6_type = 379 { 380 .description = "ESP6", 381 .owner = THIS_MODULE, 382 .proto = IPPROTO_ESP, 383 .init_state = esp6_init_state, 384 .destructor = esp6_destroy, 385 .get_mtu = esp6_get_mtu, 386 .input = esp6_input, 387 .output = esp6_output, 388 .hdr_offset = xfrm6_find_1stfragopt, 389 }; 390 391 static struct inet6_protocol esp6_protocol = { 392 .handler = xfrm6_rcv, 393 .err_handler = esp6_err, 394 .flags = INET6_PROTO_NOPOLICY, 395 }; 396 397 static int __init esp6_init(void) 398 { 399 if (xfrm_register_type(&esp6_type, AF_INET6) < 0) { 400 printk(KERN_INFO "ipv6 esp init: can't add xfrm type\n"); 401 return -EAGAIN; 402 } 403 if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) { 404 printk(KERN_INFO "ipv6 esp init: can't add protocol\n"); 405 xfrm_unregister_type(&esp6_type, AF_INET6); 406 return -EAGAIN; 407 } 408 409 return 0; 410 } 411 412 static void __exit esp6_fini(void) 413 { 414 if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0) 415 printk(KERN_INFO "ipv6 esp close: can't remove protocol\n"); 416 if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0) 417 printk(KERN_INFO "ipv6 esp close: can't remove xfrm type\n"); 418 } 419 420 module_init(esp6_init); 421 module_exit(esp6_fini); 422 423 MODULE_LICENSE("GPL"); 424 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ESP); 425