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 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 int ret = 0; 146 147 if (!pskb_may_pull(skb, sizeof(struct ipv6_esp_hdr))) { 148 ret = -EINVAL; 149 goto out; 150 } 151 152 if (elen <= 0 || (elen & (blksize-1))) { 153 ret = -EINVAL; 154 goto out; 155 } 156 157 /* If integrity check is required, do this. */ 158 if (esp->auth.icv_full_len) { 159 u8 sum[esp->auth.icv_full_len]; 160 u8 sum1[alen]; 161 162 esp->auth.icv(esp, skb, 0, skb->len-alen, sum); 163 164 if (skb_copy_bits(skb, skb->len-alen, sum1, alen)) 165 BUG(); 166 167 if (unlikely(memcmp(sum, sum1, alen))) { 168 x->stats.integrity_failed++; 169 ret = -EINVAL; 170 goto out; 171 } 172 } 173 174 if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) { 175 ret = -EINVAL; 176 goto out; 177 } 178 179 skb->ip_summed = CHECKSUM_NONE; 180 181 esph = (struct ipv6_esp_hdr*)skb->data; 182 iph = skb->nh.ipv6h; 183 184 /* Get ivec. This can be wrong, check against another impls. */ 185 if (esp->conf.ivlen) 186 crypto_cipher_set_iv(esp->conf.tfm, esph->enc_data, crypto_tfm_alg_ivsize(esp->conf.tfm)); 187 188 { 189 u8 nexthdr[2]; 190 struct scatterlist *sg = &esp->sgbuf[0]; 191 u8 padlen; 192 193 if (unlikely(nfrags > ESP_NUM_FAST_SG)) { 194 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); 195 if (!sg) { 196 ret = -ENOMEM; 197 goto out; 198 } 199 } 200 skb_to_sgvec(skb, sg, sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen, elen); 201 crypto_cipher_decrypt(esp->conf.tfm, sg, sg, elen); 202 if (unlikely(sg != &esp->sgbuf[0])) 203 kfree(sg); 204 205 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2)) 206 BUG(); 207 208 padlen = nexthdr[0]; 209 if (padlen+2 >= elen) { 210 LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage padlen=%d, elen=%d\n", padlen+2, elen); 211 ret = -EINVAL; 212 goto out; 213 } 214 /* ... check padding bits here. Silly. :-) */ 215 216 pskb_trim(skb, skb->len - alen - padlen - 2); 217 ret = nexthdr[1]; 218 } 219 220 skb->h.raw = __skb_pull(skb, sizeof(*esph) + esp->conf.ivlen) - hdr_len; 221 222 out: 223 return ret; 224 } 225 226 static u32 esp6_get_max_size(struct xfrm_state *x, int mtu) 227 { 228 struct esp_data *esp = x->data; 229 u32 blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4); 230 231 if (x->props.mode) { 232 mtu = ALIGN(mtu + 2, blksize); 233 } else { 234 /* The worst case. */ 235 u32 padsize = ((blksize - 1) & 7) + 1; 236 mtu = ALIGN(mtu + 2, padsize) + blksize - padsize; 237 } 238 if (esp->conf.padlen) 239 mtu = ALIGN(mtu, esp->conf.padlen); 240 241 return mtu + x->props.header_len + esp->auth.icv_trunc_len; 242 } 243 244 static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 245 int type, int code, int offset, __u32 info) 246 { 247 struct ipv6hdr *iph = (struct ipv6hdr*)skb->data; 248 struct ipv6_esp_hdr *esph = (struct ipv6_esp_hdr*)(skb->data+offset); 249 struct xfrm_state *x; 250 251 if (type != ICMPV6_DEST_UNREACH && 252 type != ICMPV6_PKT_TOOBIG) 253 return; 254 255 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET6); 256 if (!x) 257 return; 258 printk(KERN_DEBUG "pmtu discovery on SA ESP/%08x/" NIP6_FMT "\n", 259 ntohl(esph->spi), NIP6(iph->daddr)); 260 xfrm_state_put(x); 261 } 262 263 static void esp6_destroy(struct xfrm_state *x) 264 { 265 struct esp_data *esp = x->data; 266 267 if (!esp) 268 return; 269 270 crypto_free_tfm(esp->conf.tfm); 271 esp->conf.tfm = NULL; 272 kfree(esp->conf.ivec); 273 esp->conf.ivec = NULL; 274 crypto_free_tfm(esp->auth.tfm); 275 esp->auth.tfm = NULL; 276 kfree(esp->auth.work_icv); 277 esp->auth.work_icv = NULL; 278 kfree(esp); 279 } 280 281 static int esp6_init_state(struct xfrm_state *x) 282 { 283 struct esp_data *esp = NULL; 284 285 /* null auth and encryption can have zero length keys */ 286 if (x->aalg) { 287 if (x->aalg->alg_key_len > 512) 288 goto error; 289 } 290 if (x->ealg == NULL) 291 goto error; 292 293 if (x->encap) 294 goto error; 295 296 esp = kzalloc(sizeof(*esp), GFP_KERNEL); 297 if (esp == NULL) 298 return -ENOMEM; 299 300 if (x->aalg) { 301 struct xfrm_algo_desc *aalg_desc; 302 303 esp->auth.key = x->aalg->alg_key; 304 esp->auth.key_len = (x->aalg->alg_key_len+7)/8; 305 esp->auth.tfm = crypto_alloc_tfm(x->aalg->alg_name, 0); 306 if (esp->auth.tfm == NULL) 307 goto error; 308 esp->auth.icv = esp_hmac_digest; 309 310 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 311 BUG_ON(!aalg_desc); 312 313 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 314 crypto_tfm_alg_digestsize(esp->auth.tfm)) { 315 printk(KERN_INFO "ESP: %s digestsize %u != %hu\n", 316 x->aalg->alg_name, 317 crypto_tfm_alg_digestsize(esp->auth.tfm), 318 aalg_desc->uinfo.auth.icv_fullbits/8); 319 goto error; 320 } 321 322 esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; 323 esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8; 324 325 esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL); 326 if (!esp->auth.work_icv) 327 goto error; 328 } 329 esp->conf.key = x->ealg->alg_key; 330 esp->conf.key_len = (x->ealg->alg_key_len+7)/8; 331 if (x->props.ealgo == SADB_EALG_NULL) 332 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_ECB); 333 else 334 esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_CBC); 335 if (esp->conf.tfm == NULL) 336 goto error; 337 esp->conf.ivlen = crypto_tfm_alg_ivsize(esp->conf.tfm); 338 esp->conf.padlen = 0; 339 if (esp->conf.ivlen) { 340 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL); 341 if (unlikely(esp->conf.ivec == NULL)) 342 goto error; 343 get_random_bytes(esp->conf.ivec, esp->conf.ivlen); 344 } 345 if (crypto_cipher_setkey(esp->conf.tfm, esp->conf.key, esp->conf.key_len)) 346 goto error; 347 x->props.header_len = sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen; 348 if (x->props.mode) 349 x->props.header_len += sizeof(struct ipv6hdr); 350 x->data = esp; 351 return 0; 352 353 error: 354 x->data = esp; 355 esp6_destroy(x); 356 x->data = NULL; 357 return -EINVAL; 358 } 359 360 static struct xfrm_type esp6_type = 361 { 362 .description = "ESP6", 363 .owner = THIS_MODULE, 364 .proto = IPPROTO_ESP, 365 .init_state = esp6_init_state, 366 .destructor = esp6_destroy, 367 .get_max_size = esp6_get_max_size, 368 .input = esp6_input, 369 .output = esp6_output 370 }; 371 372 static struct inet6_protocol esp6_protocol = { 373 .handler = xfrm6_rcv, 374 .err_handler = esp6_err, 375 .flags = INET6_PROTO_NOPOLICY, 376 }; 377 378 static int __init esp6_init(void) 379 { 380 if (xfrm_register_type(&esp6_type, AF_INET6) < 0) { 381 printk(KERN_INFO "ipv6 esp init: can't add xfrm type\n"); 382 return -EAGAIN; 383 } 384 if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) { 385 printk(KERN_INFO "ipv6 esp init: can't add protocol\n"); 386 xfrm_unregister_type(&esp6_type, AF_INET6); 387 return -EAGAIN; 388 } 389 390 return 0; 391 } 392 393 static void __exit esp6_fini(void) 394 { 395 if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0) 396 printk(KERN_INFO "ipv6 esp close: can't remove protocol\n"); 397 if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0) 398 printk(KERN_INFO "ipv6 esp close: can't remove xfrm type\n"); 399 } 400 401 module_init(esp6_init); 402 module_exit(esp6_fini); 403 404 MODULE_LICENSE("GPL"); 405