esp6.c revision 73d4f84fd001b0be67fea46e84b75e6a7a5da08e
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/config.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 <linux/icmpv6.h> 40 41static int esp6_output(struct xfrm_state *x, struct sk_buff *skb) 42{ 43 int err; 44 int hdr_len; 45 struct ipv6hdr *top_iph; 46 struct ipv6_esp_hdr *esph; 47 struct crypto_tfm *tfm; 48 struct esp_data *esp; 49 struct sk_buff *trailer; 50 int blksize; 51 int clen; 52 int alen; 53 int nfrags; 54 55 esp = x->data; 56 hdr_len = skb->h.raw - skb->data + 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 blksize = ALIGN(crypto_tfm_alg_blocksize(tfm), 4); 71 clen = ALIGN(clen + 2, blksize); 72 if (esp->conf.padlen) 73 clen = ALIGN(clen, esp->conf.padlen); 74 75 if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0) { 76 goto error; 77 } 78 79 /* Fill padding... */ 80 do { 81 int i; 82 for (i=0; i<clen-skb->len - 2; i++) 83 *(u8*)(trailer->tail + i) = i+1; 84 } while (0); 85 *(u8*)(trailer->tail + clen-skb->len - 2) = (clen - skb->len)-2; 86 pskb_put(skb, trailer, clen - skb->len); 87 88 top_iph = (struct ipv6hdr *)__skb_push(skb, hdr_len); 89 esph = (struct ipv6_esp_hdr *)skb->h.raw; 90 top_iph->payload_len = htons(skb->len + alen - sizeof(*top_iph)); 91 *(u8*)(trailer->tail - 1) = *skb->nh.raw; 92 *skb->nh.raw = IPPROTO_ESP; 93 94 esph->spi = x->id.spi; 95 esph->seq_no = htonl(++x->replay.oseq); 96 97 if (esp->conf.ivlen) 98 crypto_cipher_set_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); 99 100 do { 101 struct scatterlist *sg = &esp->sgbuf[0]; 102 103 if (unlikely(nfrags > ESP_NUM_FAST_SG)) { 104 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); 105 if (!sg) 106 goto error; 107 } 108 skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen); 109 crypto_cipher_encrypt(tfm, sg, sg, clen); 110 if (unlikely(sg != &esp->sgbuf[0])) 111 kfree(sg); 112 } while (0); 113 114 if (esp->conf.ivlen) { 115 memcpy(esph->enc_data, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); 116 crypto_cipher_get_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); 117 } 118 119 if (esp->auth.icv_full_len) { 120 esp->auth.icv(esp, skb, (u8*)esph-skb->data, 121 sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen+clen, trailer->tail); 122 pskb_put(skb, trailer, alen); 123 } 124 125 err = 0; 126 127error: 128 return err; 129} 130 131static int esp6_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb) 132{ 133 struct ipv6hdr *iph; 134 struct ipv6_esp_hdr *esph; 135 struct esp_data *esp = x->data; 136 struct sk_buff *trailer; 137 int blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4); 138 int alen = esp->auth.icv_trunc_len; 139 int elen = skb->len - sizeof(struct ipv6_esp_hdr) - esp->conf.ivlen - alen; 140 141 int hdr_len = skb->h.raw - skb->nh.raw; 142 int nfrags; 143 unsigned char *tmp_hdr = NULL; 144 int ret = 0; 145 146 if (!pskb_may_pull(skb, sizeof(struct ipv6_esp_hdr))) { 147 ret = -EINVAL; 148 goto out_nofree; 149 } 150 151 if (elen <= 0 || (elen & (blksize-1))) { 152 ret = -EINVAL; 153 goto out_nofree; 154 } 155 156 tmp_hdr = kmalloc(hdr_len, GFP_ATOMIC); 157 if (!tmp_hdr) { 158 ret = -ENOMEM; 159 goto out_nofree; 160 } 161 memcpy(tmp_hdr, skb->nh.raw, hdr_len); 162 163 /* If integrity check is required, do this. */ 164 if (esp->auth.icv_full_len) { 165 u8 sum[esp->auth.icv_full_len]; 166 u8 sum1[alen]; 167 168 esp->auth.icv(esp, skb, 0, skb->len-alen, sum); 169 170 if (skb_copy_bits(skb, skb->len-alen, sum1, alen)) 171 BUG(); 172 173 if (unlikely(memcmp(sum, sum1, alen))) { 174 x->stats.integrity_failed++; 175 ret = -EINVAL; 176 goto out; 177 } 178 } 179 180 if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) { 181 ret = -EINVAL; 182 goto out; 183 } 184 185 skb->ip_summed = CHECKSUM_NONE; 186 187 esph = (struct ipv6_esp_hdr*)skb->data; 188 iph = skb->nh.ipv6h; 189 190 /* Get ivec. This can be wrong, check against another impls. */ 191 if (esp->conf.ivlen) 192 crypto_cipher_set_iv(esp->conf.tfm, esph->enc_data, crypto_tfm_alg_ivsize(esp->conf.tfm)); 193 194 { 195 u8 nexthdr[2]; 196 struct scatterlist *sg = &esp->sgbuf[0]; 197 u8 padlen; 198 199 if (unlikely(nfrags > ESP_NUM_FAST_SG)) { 200 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); 201 if (!sg) { 202 ret = -ENOMEM; 203 goto out; 204 } 205 } 206 skb_to_sgvec(skb, sg, sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen, elen); 207 crypto_cipher_decrypt(esp->conf.tfm, sg, sg, elen); 208 if (unlikely(sg != &esp->sgbuf[0])) 209 kfree(sg); 210 211 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2)) 212 BUG(); 213 214 padlen = nexthdr[0]; 215 if (padlen+2 >= elen) { 216 LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage padlen=%d, elen=%d\n", padlen+2, elen); 217 ret = -EINVAL; 218 goto out; 219 } 220 /* ... check padding bits here. Silly. :-) */ 221 222 pskb_trim(skb, skb->len - alen - padlen - 2); 223 skb->h.raw = skb_pull(skb, sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen); 224 skb->nh.raw += sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen; 225 memcpy(skb->nh.raw, tmp_hdr, hdr_len); 226 skb->nh.ipv6h->payload_len = htons(skb->len - sizeof(struct ipv6hdr)); 227 ret = nexthdr[1]; 228 } 229 230out: 231 kfree(tmp_hdr); 232out_nofree: 233 return ret; 234} 235 236static u32 esp6_get_max_size(struct xfrm_state *x, int mtu) 237{ 238 struct esp_data *esp = x->data; 239 u32 blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4); 240 241 if (x->props.mode) { 242 mtu = ALIGN(mtu + 2, blksize); 243 } else { 244 /* The worst case. */ 245 u32 padsize = ((blksize - 1) & 7) + 1; 246 mtu = ALIGN(mtu + 2, padsize) + blksize - padsize; 247 } 248 if (esp->conf.padlen) 249 mtu = ALIGN(mtu, esp->conf.padlen); 250 251 return mtu + x->props.header_len + esp->auth.icv_trunc_len; 252} 253 254static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 255 int type, int code, int offset, __u32 info) 256{ 257 struct ipv6hdr *iph = (struct ipv6hdr*)skb->data; 258 struct ipv6_esp_hdr *esph = (struct ipv6_esp_hdr*)(skb->data+offset); 259 struct xfrm_state *x; 260 261 if (type != ICMPV6_DEST_UNREACH && 262 type != ICMPV6_PKT_TOOBIG) 263 return; 264 265 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET6); 266 if (!x) 267 return; 268 printk(KERN_DEBUG "pmtu discovery on SA ESP/%08x/" 269 "%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x\n", 270 ntohl(esph->spi), NIP6(iph->daddr)); 271 xfrm_state_put(x); 272} 273 274static void esp6_destroy(struct xfrm_state *x) 275{ 276 struct esp_data *esp = x->data; 277 278 if (!esp) 279 return; 280 281 crypto_free_tfm(esp->conf.tfm); 282 esp->conf.tfm = NULL; 283 kfree(esp->conf.ivec); 284 esp->conf.ivec = NULL; 285 crypto_free_tfm(esp->auth.tfm); 286 esp->auth.tfm = NULL; 287 kfree(esp->auth.work_icv); 288 esp->auth.work_icv = NULL; 289 kfree(esp); 290} 291 292static int esp6_init_state(struct xfrm_state *x) 293{ 294 struct esp_data *esp = NULL; 295 296 /* null auth and encryption can have zero length keys */ 297 if (x->aalg) { 298 if (x->aalg->alg_key_len > 512) 299 goto error; 300 } 301 if (x->ealg == NULL) 302 goto error; 303 304 if (x->encap) 305 goto error; 306 307 esp = kmalloc(sizeof(*esp), GFP_KERNEL); 308 if (esp == NULL) 309 return -ENOMEM; 310 311 memset(esp, 0, sizeof(*esp)); 312 313 if (x->aalg) { 314 struct xfrm_algo_desc *aalg_desc; 315 316 esp->auth.key = x->aalg->alg_key; 317 esp->auth.key_len = (x->aalg->alg_key_len+7)/8; 318 esp->auth.tfm = crypto_alloc_tfm(x->aalg->alg_name, 0); 319 if (esp->auth.tfm == NULL) 320 goto error; 321 esp->auth.icv = esp_hmac_digest; 322 323 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 324 BUG_ON(!aalg_desc); 325 326 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 327 crypto_tfm_alg_digestsize(esp->auth.tfm)) { 328 printk(KERN_INFO "ESP: %s digestsize %u != %hu\n", 329 x->aalg->alg_name, 330 crypto_tfm_alg_digestsize(esp->auth.tfm), 331 aalg_desc->uinfo.auth.icv_fullbits/8); 332 goto error; 333 } 334 335 esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; 336 esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8; 337 338 esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL); 339 if (!esp->auth.work_icv) 340 goto error; 341 } 342 esp->conf.key = x->ealg->alg_key; 343 esp->conf.key_len = (x->ealg->alg_key_len+7)/8; 344 if (x->props.ealgo == SADB_EALG_NULL) 345 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_ECB); 346 else 347 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_CBC); 348 if (esp->conf.tfm == NULL) 349 goto error; 350 esp->conf.ivlen = crypto_tfm_alg_ivsize(esp->conf.tfm); 351 esp->conf.padlen = 0; 352 if (esp->conf.ivlen) { 353 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL); 354 if (unlikely(esp->conf.ivec == NULL)) 355 goto error; 356 get_random_bytes(esp->conf.ivec, esp->conf.ivlen); 357 } 358 if (crypto_cipher_setkey(esp->conf.tfm, esp->conf.key, esp->conf.key_len)) 359 goto error; 360 x->props.header_len = sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen; 361 if (x->props.mode) 362 x->props.header_len += sizeof(struct ipv6hdr); 363 x->data = esp; 364 return 0; 365 366error: 367 x->data = esp; 368 esp6_destroy(x); 369 x->data = NULL; 370 return -EINVAL; 371} 372 373static struct xfrm_type esp6_type = 374{ 375 .description = "ESP6", 376 .owner = THIS_MODULE, 377 .proto = IPPROTO_ESP, 378 .init_state = esp6_init_state, 379 .destructor = esp6_destroy, 380 .get_max_size = esp6_get_max_size, 381 .input = esp6_input, 382 .output = esp6_output 383}; 384 385static struct inet6_protocol esp6_protocol = { 386 .handler = xfrm6_rcv, 387 .err_handler = esp6_err, 388 .flags = INET6_PROTO_NOPOLICY, 389}; 390 391static int __init esp6_init(void) 392{ 393 if (xfrm_register_type(&esp6_type, AF_INET6) < 0) { 394 printk(KERN_INFO "ipv6 esp init: can't add xfrm type\n"); 395 return -EAGAIN; 396 } 397 if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) { 398 printk(KERN_INFO "ipv6 esp init: can't add protocol\n"); 399 xfrm_unregister_type(&esp6_type, AF_INET6); 400 return -EAGAIN; 401 } 402 403 return 0; 404} 405 406static void __exit esp6_fini(void) 407{ 408 if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0) 409 printk(KERN_INFO "ipv6 esp close: can't remove protocol\n"); 410 if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0) 411 printk(KERN_INFO "ipv6 esp close: can't remove xfrm type\n"); 412} 413 414module_init(esp6_init); 415module_exit(esp6_fini); 416 417MODULE_LICENSE("GPL"); 418