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/pfkeyv2.h> 35 #include <linux/random.h> 36 #include <net/icmp.h> 37 #include <net/ipv6.h> 38 #include <linux/icmpv6.h> 39 40 static int esp6_output(struct xfrm_state *x, struct sk_buff *skb) 41 { 42 int err; 43 int hdr_len; 44 struct ipv6hdr *top_iph; 45 struct ipv6_esp_hdr *esph; 46 struct crypto_tfm *tfm; 47 struct esp_data *esp; 48 struct sk_buff *trailer; 49 int blksize; 50 int clen; 51 int alen; 52 int nfrags; 53 54 esp = x->data; 55 hdr_len = skb->h.raw - skb->data + 56 sizeof(*esph) + esp->conf.ivlen; 57 58 /* Strip IP+ESP header. */ 59 __skb_pull(skb, hdr_len); 60 61 /* Now skb is pure payload to encrypt */ 62 err = -ENOMEM; 63 64 /* Round to block size */ 65 clen = skb->len; 66 67 alen = esp->auth.icv_trunc_len; 68 tfm = esp->conf.tfm; 69 blksize = (crypto_tfm_alg_blocksize(tfm) + 3) & ~3; 70 clen = (clen + 2 + blksize-1)&~(blksize-1); 71 if (esp->conf.padlen) 72 clen = (clen + esp->conf.padlen-1)&~(esp->conf.padlen-1); 73 74 if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0) { 75 goto error; 76 } 77 78 /* Fill padding... */ 79 do { 80 int i; 81 for (i=0; i<clen-skb->len - 2; i++) 82 *(u8*)(trailer->tail + i) = i+1; 83 } while (0); 84 *(u8*)(trailer->tail + clen-skb->len - 2) = (clen - skb->len)-2; 85 pskb_put(skb, trailer, clen - skb->len); 86 87 top_iph = (struct ipv6hdr *)__skb_push(skb, hdr_len); 88 esph = (struct ipv6_esp_hdr *)skb->h.raw; 89 top_iph->payload_len = htons(skb->len + alen - sizeof(*top_iph)); 90 *(u8*)(trailer->tail - 1) = *skb->nh.raw; 91 *skb->nh.raw = IPPROTO_ESP; 92 93 esph->spi = x->id.spi; 94 esph->seq_no = htonl(++x->replay.oseq); 95 96 if (esp->conf.ivlen) 97 crypto_cipher_set_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); 98 99 do { 100 struct scatterlist *sg = &esp->sgbuf[0]; 101 102 if (unlikely(nfrags > ESP_NUM_FAST_SG)) { 103 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); 104 if (!sg) 105 goto error; 106 } 107 skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen); 108 crypto_cipher_encrypt(tfm, sg, sg, clen); 109 if (unlikely(sg != &esp->sgbuf[0])) 110 kfree(sg); 111 } while (0); 112 113 if (esp->conf.ivlen) { 114 memcpy(esph->enc_data, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); 115 crypto_cipher_get_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); 116 } 117 118 if (esp->auth.icv_full_len) { 119 esp->auth.icv(esp, skb, (u8*)esph-skb->data, 120 sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen+clen, trailer->tail); 121 pskb_put(skb, trailer, alen); 122 } 123 124 err = 0; 125 126 error: 127 return err; 128 } 129 130 static int esp6_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb) 131 { 132 struct ipv6hdr *iph; 133 struct ipv6_esp_hdr *esph; 134 struct esp_data *esp = x->data; 135 struct sk_buff *trailer; 136 int blksize = crypto_tfm_alg_blocksize(esp->conf.tfm); 137 int alen = esp->auth.icv_trunc_len; 138 int elen = skb->len - sizeof(struct ipv6_esp_hdr) - esp->conf.ivlen - alen; 139 140 int hdr_len = skb->h.raw - skb->nh.raw; 141 int nfrags; 142 unsigned char *tmp_hdr = NULL; 143 int ret = 0; 144 145 if (!pskb_may_pull(skb, sizeof(struct ipv6_esp_hdr))) { 146 ret = -EINVAL; 147 goto out_nofree; 148 } 149 150 if (elen <= 0 || (elen & (blksize-1))) { 151 ret = -EINVAL; 152 goto out_nofree; 153 } 154 155 tmp_hdr = kmalloc(hdr_len, GFP_ATOMIC); 156 if (!tmp_hdr) { 157 ret = -ENOMEM; 158 goto out_nofree; 159 } 160 memcpy(tmp_hdr, skb->nh.raw, hdr_len); 161 162 /* If integrity check is required, do this. */ 163 if (esp->auth.icv_full_len) { 164 u8 sum[esp->auth.icv_full_len]; 165 u8 sum1[alen]; 166 167 esp->auth.icv(esp, skb, 0, skb->len-alen, sum); 168 169 if (skb_copy_bits(skb, skb->len-alen, sum1, alen)) 170 BUG(); 171 172 if (unlikely(memcmp(sum, sum1, alen))) { 173 x->stats.integrity_failed++; 174 ret = -EINVAL; 175 goto out; 176 } 177 } 178 179 if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) { 180 ret = -EINVAL; 181 goto out; 182 } 183 184 skb->ip_summed = CHECKSUM_NONE; 185 186 esph = (struct ipv6_esp_hdr*)skb->data; 187 iph = skb->nh.ipv6h; 188 189 /* Get ivec. This can be wrong, check against another impls. */ 190 if (esp->conf.ivlen) 191 crypto_cipher_set_iv(esp->conf.tfm, esph->enc_data, crypto_tfm_alg_ivsize(esp->conf.tfm)); 192 193 { 194 u8 nexthdr[2]; 195 struct scatterlist *sg = &esp->sgbuf[0]; 196 u8 padlen; 197 198 if (unlikely(nfrags > ESP_NUM_FAST_SG)) { 199 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); 200 if (!sg) { 201 ret = -ENOMEM; 202 goto out; 203 } 204 } 205 skb_to_sgvec(skb, sg, sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen, elen); 206 crypto_cipher_decrypt(esp->conf.tfm, sg, sg, elen); 207 if (unlikely(sg != &esp->sgbuf[0])) 208 kfree(sg); 209 210 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2)) 211 BUG(); 212 213 padlen = nexthdr[0]; 214 if (padlen+2 >= elen) { 215 LIMIT_NETDEBUG( 216 printk(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 } 229 230 out: 231 kfree(tmp_hdr); 232 out_nofree: 233 return ret; 234 } 235 236 static u32 esp6_get_max_size(struct xfrm_state *x, int mtu) 237 { 238 struct esp_data *esp = x->data; 239 u32 blksize = crypto_tfm_alg_blocksize(esp->conf.tfm); 240 241 if (x->props.mode) { 242 mtu = (mtu + 2 + blksize-1)&~(blksize-1); 243 } else { 244 /* The worst case. */ 245 mtu += 2 + blksize; 246 } 247 if (esp->conf.padlen) 248 mtu = (mtu + esp->conf.padlen-1)&~(esp->conf.padlen-1); 249 250 return mtu + x->props.header_len + esp->auth.icv_full_len; 251 } 252 253 static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 254 int type, int code, int offset, __u32 info) 255 { 256 struct ipv6hdr *iph = (struct ipv6hdr*)skb->data; 257 struct ipv6_esp_hdr *esph = (struct ipv6_esp_hdr*)(skb->data+offset); 258 struct xfrm_state *x; 259 260 if (type != ICMPV6_DEST_UNREACH && 261 type != ICMPV6_PKT_TOOBIG) 262 return; 263 264 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET6); 265 if (!x) 266 return; 267 printk(KERN_DEBUG "pmtu discovery on SA ESP/%08x/" 268 "%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x\n", 269 ntohl(esph->spi), NIP6(iph->daddr)); 270 xfrm_state_put(x); 271 } 272 273 static void esp6_destroy(struct xfrm_state *x) 274 { 275 struct esp_data *esp = x->data; 276 277 if (!esp) 278 return; 279 280 if (esp->conf.tfm) { 281 crypto_free_tfm(esp->conf.tfm); 282 esp->conf.tfm = NULL; 283 } 284 if (esp->conf.ivec) { 285 kfree(esp->conf.ivec); 286 esp->conf.ivec = NULL; 287 } 288 if (esp->auth.tfm) { 289 crypto_free_tfm(esp->auth.tfm); 290 esp->auth.tfm = NULL; 291 } 292 if (esp->auth.work_icv) { 293 kfree(esp->auth.work_icv); 294 esp->auth.work_icv = NULL; 295 } 296 kfree(esp); 297 } 298 299 static int esp6_init_state(struct xfrm_state *x, void *args) 300 { 301 struct esp_data *esp = NULL; 302 303 /* null auth and encryption can have zero length keys */ 304 if (x->aalg) { 305 if (x->aalg->alg_key_len > 512) 306 goto error; 307 } 308 if (x->ealg == NULL) 309 goto error; 310 311 if (x->encap) 312 goto error; 313 314 esp = kmalloc(sizeof(*esp), GFP_KERNEL); 315 if (esp == NULL) 316 return -ENOMEM; 317 318 memset(esp, 0, sizeof(*esp)); 319 320 if (x->aalg) { 321 struct xfrm_algo_desc *aalg_desc; 322 323 esp->auth.key = x->aalg->alg_key; 324 esp->auth.key_len = (x->aalg->alg_key_len+7)/8; 325 esp->auth.tfm = crypto_alloc_tfm(x->aalg->alg_name, 0); 326 if (esp->auth.tfm == NULL) 327 goto error; 328 esp->auth.icv = esp_hmac_digest; 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_tfm_alg_digestsize(esp->auth.tfm)) { 335 printk(KERN_INFO "ESP: %s digestsize %u != %hu\n", 336 x->aalg->alg_name, 337 crypto_tfm_alg_digestsize(esp->auth.tfm), 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 if (x->props.ealgo == SADB_EALG_NULL) 352 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_ECB); 353 else 354 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_CBC); 355 if (esp->conf.tfm == NULL) 356 goto error; 357 esp->conf.ivlen = crypto_tfm_alg_ivsize(esp->conf.tfm); 358 esp->conf.padlen = 0; 359 if (esp->conf.ivlen) { 360 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL); 361 if (unlikely(esp->conf.ivec == NULL)) 362 goto error; 363 get_random_bytes(esp->conf.ivec, esp->conf.ivlen); 364 } 365 if (crypto_cipher_setkey(esp->conf.tfm, esp->conf.key, esp->conf.key_len)) 366 goto error; 367 x->props.header_len = sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen; 368 if (x->props.mode) 369 x->props.header_len += sizeof(struct ipv6hdr); 370 x->data = esp; 371 return 0; 372 373 error: 374 x->data = esp; 375 esp6_destroy(x); 376 x->data = NULL; 377 return -EINVAL; 378 } 379 380 static struct xfrm_type esp6_type = 381 { 382 .description = "ESP6", 383 .owner = THIS_MODULE, 384 .proto = IPPROTO_ESP, 385 .init_state = esp6_init_state, 386 .destructor = esp6_destroy, 387 .get_max_size = esp6_get_max_size, 388 .input = esp6_input, 389 .output = esp6_output 390 }; 391 392 static struct inet6_protocol esp6_protocol = { 393 .handler = xfrm6_rcv, 394 .err_handler = esp6_err, 395 .flags = INET6_PROTO_NOPOLICY, 396 }; 397 398 static int __init esp6_init(void) 399 { 400 if (xfrm_register_type(&esp6_type, AF_INET6) < 0) { 401 printk(KERN_INFO "ipv6 esp init: can't add xfrm type\n"); 402 return -EAGAIN; 403 } 404 if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) { 405 printk(KERN_INFO "ipv6 esp init: can't add protocol\n"); 406 xfrm_unregister_type(&esp6_type, AF_INET6); 407 return -EAGAIN; 408 } 409 410 return 0; 411 } 412 413 static void __exit esp6_fini(void) 414 { 415 if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0) 416 printk(KERN_INFO "ipv6 esp close: can't remove protocol\n"); 417 if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0) 418 printk(KERN_INFO "ipv6 esp close: can't remove xfrm type\n"); 419 } 420 421 module_init(esp6_init); 422 module_exit(esp6_fini); 423 424 MODULE_LICENSE("GPL"); 425