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 xfrm_aevent_doreplay(x); 98 99 if (esp->conf.ivlen) 100 crypto_cipher_set_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); 101 102 do { 103 struct scatterlist *sg = &esp->sgbuf[0]; 104 105 if (unlikely(nfrags > ESP_NUM_FAST_SG)) { 106 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); 107 if (!sg) 108 goto error; 109 } 110 skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen); 111 crypto_cipher_encrypt(tfm, sg, sg, clen); 112 if (unlikely(sg != &esp->sgbuf[0])) 113 kfree(sg); 114 } while (0); 115 116 if (esp->conf.ivlen) { 117 memcpy(esph->enc_data, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); 118 crypto_cipher_get_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); 119 } 120 121 if (esp->auth.icv_full_len) { 122 esp->auth.icv(esp, skb, (u8*)esph-skb->data, 123 sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen+clen, trailer->tail); 124 pskb_put(skb, trailer, alen); 125 } 126 127 err = 0; 128 129 error: 130 return err; 131 } 132 133 static int esp6_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb) 134 { 135 struct ipv6hdr *iph; 136 struct ipv6_esp_hdr *esph; 137 struct esp_data *esp = x->data; 138 struct sk_buff *trailer; 139 int blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4); 140 int alen = esp->auth.icv_trunc_len; 141 int elen = skb->len - sizeof(struct ipv6_esp_hdr) - esp->conf.ivlen - alen; 142 143 int hdr_len = skb->h.raw - skb->nh.raw; 144 int nfrags; 145 unsigned char *tmp_hdr = NULL; 146 int ret = 0; 147 148 if (!pskb_may_pull(skb, sizeof(struct ipv6_esp_hdr))) { 149 ret = -EINVAL; 150 goto out_nofree; 151 } 152 153 if (elen <= 0 || (elen & (blksize-1))) { 154 ret = -EINVAL; 155 goto out_nofree; 156 } 157 158 tmp_hdr = kmalloc(hdr_len, GFP_ATOMIC); 159 if (!tmp_hdr) { 160 ret = -ENOMEM; 161 goto out_nofree; 162 } 163 memcpy(tmp_hdr, skb->nh.raw, hdr_len); 164 165 /* If integrity check is required, do this. */ 166 if (esp->auth.icv_full_len) { 167 u8 sum[esp->auth.icv_full_len]; 168 u8 sum1[alen]; 169 170 esp->auth.icv(esp, skb, 0, skb->len-alen, sum); 171 172 if (skb_copy_bits(skb, skb->len-alen, sum1, alen)) 173 BUG(); 174 175 if (unlikely(memcmp(sum, sum1, 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 ipv6_esp_hdr*)skb->data; 190 iph = skb->nh.ipv6h; 191 192 /* Get ivec. This can be wrong, check against another impls. */ 193 if (esp->conf.ivlen) 194 crypto_cipher_set_iv(esp->conf.tfm, esph->enc_data, crypto_tfm_alg_ivsize(esp->conf.tfm)); 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(struct ipv6_esp_hdr) + esp->conf.ivlen, elen); 209 crypto_cipher_decrypt(esp->conf.tfm, sg, sg, elen); 210 if (unlikely(sg != &esp->sgbuf[0])) 211 kfree(sg); 212 213 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2)) 214 BUG(); 215 216 padlen = nexthdr[0]; 217 if (padlen+2 >= elen) { 218 LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage padlen=%d, elen=%d\n", padlen+2, elen); 219 ret = -EINVAL; 220 goto out; 221 } 222 /* ... check padding bits here. Silly. :-) */ 223 224 pskb_trim(skb, skb->len - alen - padlen - 2); 225 skb->h.raw = skb_pull(skb, sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen); 226 skb->nh.raw += sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen; 227 memcpy(skb->nh.raw, tmp_hdr, hdr_len); 228 skb->nh.ipv6h->payload_len = htons(skb->len - sizeof(struct ipv6hdr)); 229 ret = nexthdr[1]; 230 } 231 232 out: 233 kfree(tmp_hdr); 234 out_nofree: 235 return ret; 236 } 237 238 static u32 esp6_get_max_size(struct xfrm_state *x, int mtu) 239 { 240 struct esp_data *esp = x->data; 241 u32 blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4); 242 243 if (x->props.mode) { 244 mtu = ALIGN(mtu + 2, blksize); 245 } else { 246 /* The worst case. */ 247 u32 padsize = ((blksize - 1) & 7) + 1; 248 mtu = ALIGN(mtu + 2, padsize) + blksize - padsize; 249 } 250 if (esp->conf.padlen) 251 mtu = ALIGN(mtu, esp->conf.padlen); 252 253 return mtu + x->props.header_len + esp->auth.icv_trunc_len; 254 } 255 256 static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 257 int type, int code, int offset, __u32 info) 258 { 259 struct ipv6hdr *iph = (struct ipv6hdr*)skb->data; 260 struct ipv6_esp_hdr *esph = (struct ipv6_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_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 = kzalloc(sizeof(*esp), GFP_KERNEL); 309 if (esp == NULL) 310 return -ENOMEM; 311 312 if (x->aalg) { 313 struct xfrm_algo_desc *aalg_desc; 314 315 esp->auth.key = x->aalg->alg_key; 316 esp->auth.key_len = (x->aalg->alg_key_len+7)/8; 317 esp->auth.tfm = crypto_alloc_tfm(x->aalg->alg_name, 0); 318 if (esp->auth.tfm == NULL) 319 goto error; 320 esp->auth.icv = esp_hmac_digest; 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_tfm_alg_digestsize(esp->auth.tfm)) { 327 printk(KERN_INFO "ESP: %s digestsize %u != %hu\n", 328 x->aalg->alg_name, 329 crypto_tfm_alg_digestsize(esp->auth.tfm), 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 esp->conf.key = x->ealg->alg_key; 342 esp->conf.key_len = (x->ealg->alg_key_len+7)/8; 343 if (x->props.ealgo == SADB_EALG_NULL) 344 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_ECB); 345 else 346 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_CBC); 347 if (esp->conf.tfm == NULL) 348 goto error; 349 esp->conf.ivlen = crypto_tfm_alg_ivsize(esp->conf.tfm); 350 esp->conf.padlen = 0; 351 if (esp->conf.ivlen) { 352 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL); 353 if (unlikely(esp->conf.ivec == NULL)) 354 goto error; 355 get_random_bytes(esp->conf.ivec, esp->conf.ivlen); 356 } 357 if (crypto_cipher_setkey(esp->conf.tfm, esp->conf.key, esp->conf.key_len)) 358 goto error; 359 x->props.header_len = sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen; 360 if (x->props.mode) 361 x->props.header_len += sizeof(struct ipv6hdr); 362 x->data = esp; 363 return 0; 364 365 error: 366 x->data = esp; 367 esp6_destroy(x); 368 x->data = NULL; 369 return -EINVAL; 370 } 371 372 static struct xfrm_type esp6_type = 373 { 374 .description = "ESP6", 375 .owner = THIS_MODULE, 376 .proto = IPPROTO_ESP, 377 .init_state = esp6_init_state, 378 .destructor = esp6_destroy, 379 .get_max_size = esp6_get_max_size, 380 .input = esp6_input, 381 .output = esp6_output 382 }; 383 384 static struct inet6_protocol esp6_protocol = { 385 .handler = xfrm6_rcv, 386 .err_handler = esp6_err, 387 .flags = INET6_PROTO_NOPOLICY, 388 }; 389 390 static int __init esp6_init(void) 391 { 392 if (xfrm_register_type(&esp6_type, AF_INET6) < 0) { 393 printk(KERN_INFO "ipv6 esp init: can't add xfrm type\n"); 394 return -EAGAIN; 395 } 396 if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) { 397 printk(KERN_INFO "ipv6 esp init: can't add protocol\n"); 398 xfrm_unregister_type(&esp6_type, AF_INET6); 399 return -EAGAIN; 400 } 401 402 return 0; 403 } 404 405 static void __exit esp6_fini(void) 406 { 407 if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0) 408 printk(KERN_INFO "ipv6 esp close: can't remove protocol\n"); 409 if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0) 410 printk(KERN_INFO "ipv6 esp close: can't remove xfrm type\n"); 411 } 412 413 module_init(esp6_init); 414 module_exit(esp6_fini); 415 416 MODULE_LICENSE("GPL"); 417