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 <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 int hdr_len; 46 struct ipv6hdr *top_iph; 47 struct ipv6_esp_hdr *esph; 48 struct crypto_tfm *tfm; 49 struct esp_data *esp; 50 struct sk_buff *trailer; 51 int blksize; 52 int clen; 53 int alen; 54 int nfrags; 55 56 esp = x->data; 57 hdr_len = skb->h.raw - skb->data + 58 sizeof(*esph) + esp->conf.ivlen; 59 60 /* Strip IP+ESP header. */ 61 __skb_pull(skb, hdr_len); 62 63 /* Now skb is pure payload to encrypt */ 64 err = -ENOMEM; 65 66 /* Round to block size */ 67 clen = skb->len; 68 69 alen = esp->auth.icv_trunc_len; 70 tfm = esp->conf.tfm; 71 blksize = ALIGN(crypto_tfm_alg_blocksize(tfm), 4); 72 clen = ALIGN(clen + 2, blksize); 73 if (esp->conf.padlen) 74 clen = ALIGN(clen, esp->conf.padlen); 75 76 if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0) { 77 goto error; 78 } 79 80 /* Fill padding... */ 81 do { 82 int i; 83 for (i=0; i<clen-skb->len - 2; i++) 84 *(u8*)(trailer->tail + i) = i+1; 85 } while (0); 86 *(u8*)(trailer->tail + clen-skb->len - 2) = (clen - skb->len)-2; 87 pskb_put(skb, trailer, clen - skb->len); 88 89 top_iph = (struct ipv6hdr *)__skb_push(skb, hdr_len); 90 esph = (struct ipv6_esp_hdr *)skb->h.raw; 91 top_iph->payload_len = htons(skb->len + alen - sizeof(*top_iph)); 92 *(u8*)(trailer->tail - 1) = *skb->nh.raw; 93 *skb->nh.raw = IPPROTO_ESP; 94 95 esph->spi = x->id.spi; 96 esph->seq_no = htonl(++x->replay.oseq); 97 98 if (esp->conf.ivlen) 99 crypto_cipher_set_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); 100 101 do { 102 struct scatterlist *sg = &esp->sgbuf[0]; 103 104 if (unlikely(nfrags > ESP_NUM_FAST_SG)) { 105 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); 106 if (!sg) 107 goto error; 108 } 109 skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen); 110 crypto_cipher_encrypt(tfm, sg, sg, clen); 111 if (unlikely(sg != &esp->sgbuf[0])) 112 kfree(sg); 113 } while (0); 114 115 if (esp->conf.ivlen) { 116 memcpy(esph->enc_data, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); 117 crypto_cipher_get_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); 118 } 119 120 if (esp->auth.icv_full_len) { 121 esp->auth.icv(esp, skb, (u8*)esph-skb->data, 122 sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen+clen, trailer->tail); 123 pskb_put(skb, trailer, alen); 124 } 125 126 err = 0; 127 128 error: 129 return err; 130 } 131 132 static int esp6_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb) 133 { 134 struct ipv6hdr *iph; 135 struct ipv6_esp_hdr *esph; 136 struct esp_data *esp = x->data; 137 struct sk_buff *trailer; 138 int blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4); 139 int alen = esp->auth.icv_trunc_len; 140 int elen = skb->len - sizeof(struct ipv6_esp_hdr) - esp->conf.ivlen - alen; 141 142 int hdr_len = skb->h.raw - skb->nh.raw; 143 int nfrags; 144 unsigned char *tmp_hdr = NULL; 145 int ret = 0; 146 147 if (!pskb_may_pull(skb, sizeof(struct ipv6_esp_hdr))) { 148 ret = -EINVAL; 149 goto out_nofree; 150 } 151 152 if (elen <= 0 || (elen & (blksize-1))) { 153 ret = -EINVAL; 154 goto out_nofree; 155 } 156 157 tmp_hdr = kmalloc(hdr_len, GFP_ATOMIC); 158 if (!tmp_hdr) { 159 ret = -ENOMEM; 160 goto out_nofree; 161 } 162 memcpy(tmp_hdr, skb->nh.raw, hdr_len); 163 164 /* If integrity check is required, do this. */ 165 if (esp->auth.icv_full_len) { 166 u8 sum[esp->auth.icv_full_len]; 167 u8 sum1[alen]; 168 169 esp->auth.icv(esp, skb, 0, skb->len-alen, sum); 170 171 if (skb_copy_bits(skb, skb->len-alen, sum1, alen)) 172 BUG(); 173 174 if (unlikely(memcmp(sum, sum1, alen))) { 175 x->stats.integrity_failed++; 176 ret = -EINVAL; 177 goto out; 178 } 179 } 180 181 if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) { 182 ret = -EINVAL; 183 goto out; 184 } 185 186 skb->ip_summed = CHECKSUM_NONE; 187 188 esph = (struct ipv6_esp_hdr*)skb->data; 189 iph = skb->nh.ipv6h; 190 191 /* Get ivec. This can be wrong, check against another impls. */ 192 if (esp->conf.ivlen) 193 crypto_cipher_set_iv(esp->conf.tfm, esph->enc_data, crypto_tfm_alg_ivsize(esp->conf.tfm)); 194 195 { 196 u8 nexthdr[2]; 197 struct scatterlist *sg = &esp->sgbuf[0]; 198 u8 padlen; 199 200 if (unlikely(nfrags > ESP_NUM_FAST_SG)) { 201 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); 202 if (!sg) { 203 ret = -ENOMEM; 204 goto out; 205 } 206 } 207 skb_to_sgvec(skb, sg, sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen, elen); 208 crypto_cipher_decrypt(esp->conf.tfm, sg, sg, elen); 209 if (unlikely(sg != &esp->sgbuf[0])) 210 kfree(sg); 211 212 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2)) 213 BUG(); 214 215 padlen = nexthdr[0]; 216 if (padlen+2 >= elen) { 217 LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage padlen=%d, elen=%d\n", padlen+2, elen); 218 ret = -EINVAL; 219 goto out; 220 } 221 /* ... check padding bits here. Silly. :-) */ 222 223 pskb_trim(skb, skb->len - alen - padlen - 2); 224 skb->h.raw = skb_pull(skb, sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen); 225 skb->nh.raw += sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen; 226 memcpy(skb->nh.raw, tmp_hdr, hdr_len); 227 skb->nh.ipv6h->payload_len = htons(skb->len - sizeof(struct ipv6hdr)); 228 ret = nexthdr[1]; 229 } 230 231 out: 232 kfree(tmp_hdr); 233 out_nofree: 234 return ret; 235 } 236 237 static u32 esp6_get_max_size(struct xfrm_state *x, int mtu) 238 { 239 struct esp_data *esp = x->data; 240 u32 blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4); 241 242 if (x->props.mode) { 243 mtu = ALIGN(mtu + 2, blksize); 244 } else { 245 /* The worst case. */ 246 u32 padsize = ((blksize - 1) & 7) + 1; 247 mtu = ALIGN(mtu + 2, padsize) + blksize - padsize; 248 } 249 if (esp->conf.padlen) 250 mtu = ALIGN(mtu, esp->conf.padlen); 251 252 return mtu + x->props.header_len + esp->auth.icv_trunc_len; 253 } 254 255 static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 256 int type, int code, int offset, __u32 info) 257 { 258 struct ipv6hdr *iph = (struct ipv6hdr*)skb->data; 259 struct ipv6_esp_hdr *esph = (struct ipv6_esp_hdr*)(skb->data+offset); 260 struct xfrm_state *x; 261 262 if (type != ICMPV6_DEST_UNREACH && 263 type != ICMPV6_PKT_TOOBIG) 264 return; 265 266 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET6); 267 if (!x) 268 return; 269 printk(KERN_DEBUG "pmtu discovery on SA ESP/%08x/" 270 "%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x\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_tfm(esp->conf.tfm); 283 esp->conf.tfm = NULL; 284 kfree(esp->conf.ivec); 285 esp->conf.ivec = NULL; 286 crypto_free_tfm(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; 296 297 /* null auth and encryption can have zero length keys */ 298 if (x->aalg) { 299 if (x->aalg->alg_key_len > 512) 300 goto error; 301 } 302 if (x->ealg == NULL) 303 goto error; 304 305 if (x->encap) 306 goto error; 307 308 esp = kmalloc(sizeof(*esp), GFP_KERNEL); 309 if (esp == NULL) 310 return -ENOMEM; 311 312 memset(esp, 0, sizeof(*esp)); 313 314 if (x->aalg) { 315 struct xfrm_algo_desc *aalg_desc; 316 317 esp->auth.key = x->aalg->alg_key; 318 esp->auth.key_len = (x->aalg->alg_key_len+7)/8; 319 esp->auth.tfm = crypto_alloc_tfm(x->aalg->alg_name, 0); 320 if (esp->auth.tfm == NULL) 321 goto error; 322 esp->auth.icv = esp_hmac_digest; 323 324 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 325 BUG_ON(!aalg_desc); 326 327 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 328 crypto_tfm_alg_digestsize(esp->auth.tfm)) { 329 printk(KERN_INFO "ESP: %s digestsize %u != %hu\n", 330 x->aalg->alg_name, 331 crypto_tfm_alg_digestsize(esp->auth.tfm), 332 aalg_desc->uinfo.auth.icv_fullbits/8); 333 goto error; 334 } 335 336 esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; 337 esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8; 338 339 esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL); 340 if (!esp->auth.work_icv) 341 goto error; 342 } 343 esp->conf.key = x->ealg->alg_key; 344 esp->conf.key_len = (x->ealg->alg_key_len+7)/8; 345 if (x->props.ealgo == SADB_EALG_NULL) 346 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_ECB); 347 else 348 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_CBC); 349 if (esp->conf.tfm == NULL) 350 goto error; 351 esp->conf.ivlen = crypto_tfm_alg_ivsize(esp->conf.tfm); 352 esp->conf.padlen = 0; 353 if (esp->conf.ivlen) { 354 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL); 355 if (unlikely(esp->conf.ivec == NULL)) 356 goto error; 357 get_random_bytes(esp->conf.ivec, esp->conf.ivlen); 358 } 359 if (crypto_cipher_setkey(esp->conf.tfm, esp->conf.key, esp->conf.key_len)) 360 goto error; 361 x->props.header_len = sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen; 362 if (x->props.mode) 363 x->props.header_len += sizeof(struct ipv6hdr); 364 x->data = esp; 365 return 0; 366 367 error: 368 x->data = esp; 369 esp6_destroy(x); 370 x->data = NULL; 371 return -EINVAL; 372 } 373 374 static struct xfrm_type esp6_type = 375 { 376 .description = "ESP6", 377 .owner = THIS_MODULE, 378 .proto = IPPROTO_ESP, 379 .init_state = esp6_init_state, 380 .destructor = esp6_destroy, 381 .get_max_size = esp6_get_max_size, 382 .input = esp6_input, 383 .output = esp6_output 384 }; 385 386 static struct inet6_protocol esp6_protocol = { 387 .handler = xfrm6_rcv, 388 .err_handler = esp6_err, 389 .flags = INET6_PROTO_NOPOLICY, 390 }; 391 392 static int __init esp6_init(void) 393 { 394 if (xfrm_register_type(&esp6_type, AF_INET6) < 0) { 395 printk(KERN_INFO "ipv6 esp init: can't add xfrm type\n"); 396 return -EAGAIN; 397 } 398 if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) { 399 printk(KERN_INFO "ipv6 esp init: can't add protocol\n"); 400 xfrm_unregister_type(&esp6_type, AF_INET6); 401 return -EAGAIN; 402 } 403 404 return 0; 405 } 406 407 static void __exit esp6_fini(void) 408 { 409 if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0) 410 printk(KERN_INFO "ipv6 esp close: can't remove protocol\n"); 411 if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0) 412 printk(KERN_INFO "ipv6 esp close: can't remove xfrm type\n"); 413 } 414 415 module_init(esp6_init); 416 module_exit(esp6_fini); 417 418 MODULE_LICENSE("GPL"); 419