esp6.c 11 KB

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  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. #include <linux/err.h>
  27. #include <linux/module.h>
  28. #include <net/ip.h>
  29. #include <net/xfrm.h>
  30. #include <net/esp.h>
  31. #include <asm/scatterlist.h>
  32. #include <linux/crypto.h>
  33. #include <linux/kernel.h>
  34. #include <linux/pfkeyv2.h>
  35. #include <linux/random.h>
  36. #include <net/icmp.h>
  37. #include <net/ipv6.h>
  38. #include <net/protocol.h>
  39. #include <linux/icmpv6.h>
  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_blkcipher *tfm;
  47. struct blkcipher_desc desc;
  48. struct esp_data *esp;
  49. struct sk_buff *trailer;
  50. int blksize;
  51. int clen;
  52. int alen;
  53. int nfrags;
  54. esp = x->data;
  55. hdr_len = skb->h.raw - skb->data +
  56. sizeof(*esph) + esp->conf.ivlen;
  57. /* Strip IP+ESP header. */
  58. __skb_pull(skb, hdr_len);
  59. /* Now skb is pure payload to encrypt */
  60. err = -ENOMEM;
  61. /* Round to block size */
  62. clen = skb->len;
  63. alen = esp->auth.icv_trunc_len;
  64. tfm = esp->conf.tfm;
  65. desc.tfm = tfm;
  66. desc.flags = 0;
  67. blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
  68. clen = ALIGN(clen + 2, blksize);
  69. if (esp->conf.padlen)
  70. clen = ALIGN(clen, esp->conf.padlen);
  71. if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0) {
  72. goto error;
  73. }
  74. /* Fill padding... */
  75. do {
  76. int i;
  77. for (i=0; i<clen-skb->len - 2; i++)
  78. *(u8*)(trailer->tail + i) = i+1;
  79. } while (0);
  80. *(u8*)(trailer->tail + clen-skb->len - 2) = (clen - skb->len)-2;
  81. pskb_put(skb, trailer, clen - skb->len);
  82. top_iph = (struct ipv6hdr *)__skb_push(skb, hdr_len);
  83. esph = (struct ipv6_esp_hdr *)skb->h.raw;
  84. top_iph->payload_len = htons(skb->len + alen - sizeof(*top_iph));
  85. *(u8*)(trailer->tail - 1) = *skb->nh.raw;
  86. *skb->nh.raw = IPPROTO_ESP;
  87. esph->spi = x->id.spi;
  88. esph->seq_no = htonl(++x->replay.oseq);
  89. xfrm_aevent_doreplay(x);
  90. if (esp->conf.ivlen) {
  91. if (unlikely(!esp->conf.ivinitted)) {
  92. get_random_bytes(esp->conf.ivec, esp->conf.ivlen);
  93. esp->conf.ivinitted = 1;
  94. }
  95. crypto_blkcipher_set_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
  96. }
  97. do {
  98. struct scatterlist *sg = &esp->sgbuf[0];
  99. if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
  100. sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
  101. if (!sg)
  102. goto error;
  103. }
  104. skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen);
  105. err = crypto_blkcipher_encrypt(&desc, sg, sg, clen);
  106. if (unlikely(sg != &esp->sgbuf[0]))
  107. kfree(sg);
  108. } while (0);
  109. if (unlikely(err))
  110. goto error;
  111. if (esp->conf.ivlen) {
  112. memcpy(esph->enc_data, esp->conf.ivec, esp->conf.ivlen);
  113. crypto_blkcipher_get_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
  114. }
  115. if (esp->auth.icv_full_len) {
  116. err = esp_mac_digest(esp, skb, (u8 *)esph - skb->data,
  117. sizeof(*esph) + esp->conf.ivlen + clen);
  118. memcpy(pskb_put(skb, trailer, alen), esp->auth.work_icv, alen);
  119. }
  120. error:
  121. return err;
  122. }
  123. static int esp6_input(struct xfrm_state *x, struct sk_buff *skb)
  124. {
  125. struct ipv6hdr *iph;
  126. struct ipv6_esp_hdr *esph;
  127. struct esp_data *esp = x->data;
  128. struct crypto_blkcipher *tfm = esp->conf.tfm;
  129. struct blkcipher_desc desc = { .tfm = tfm };
  130. struct sk_buff *trailer;
  131. int blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
  132. int alen = esp->auth.icv_trunc_len;
  133. int elen = skb->len - sizeof(struct ipv6_esp_hdr) - esp->conf.ivlen - alen;
  134. int hdr_len = skb->h.raw - skb->nh.raw;
  135. int nfrags;
  136. int ret = 0;
  137. if (!pskb_may_pull(skb, sizeof(struct ipv6_esp_hdr))) {
  138. ret = -EINVAL;
  139. goto out;
  140. }
  141. if (elen <= 0 || (elen & (blksize-1))) {
  142. ret = -EINVAL;
  143. goto out;
  144. }
  145. /* If integrity check is required, do this. */
  146. if (esp->auth.icv_full_len) {
  147. u8 sum[alen];
  148. ret = esp_mac_digest(esp, skb, 0, skb->len - alen);
  149. if (ret)
  150. goto out;
  151. if (skb_copy_bits(skb, skb->len - alen, sum, alen))
  152. BUG();
  153. if (unlikely(memcmp(esp->auth.work_icv, sum, alen))) {
  154. x->stats.integrity_failed++;
  155. ret = -EINVAL;
  156. goto out;
  157. }
  158. }
  159. if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) {
  160. ret = -EINVAL;
  161. goto out;
  162. }
  163. skb->ip_summed = CHECKSUM_NONE;
  164. esph = (struct ipv6_esp_hdr*)skb->data;
  165. iph = skb->nh.ipv6h;
  166. /* Get ivec. This can be wrong, check against another impls. */
  167. if (esp->conf.ivlen)
  168. crypto_blkcipher_set_iv(tfm, esph->enc_data, esp->conf.ivlen);
  169. {
  170. u8 nexthdr[2];
  171. struct scatterlist *sg = &esp->sgbuf[0];
  172. u8 padlen;
  173. if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
  174. sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
  175. if (!sg) {
  176. ret = -ENOMEM;
  177. goto out;
  178. }
  179. }
  180. skb_to_sgvec(skb, sg, sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen, elen);
  181. ret = crypto_blkcipher_decrypt(&desc, sg, sg, elen);
  182. if (unlikely(sg != &esp->sgbuf[0]))
  183. kfree(sg);
  184. if (unlikely(ret))
  185. goto out;
  186. if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2))
  187. BUG();
  188. padlen = nexthdr[0];
  189. if (padlen+2 >= elen) {
  190. LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage padlen=%d, elen=%d\n", padlen+2, elen);
  191. ret = -EINVAL;
  192. goto out;
  193. }
  194. /* ... check padding bits here. Silly. :-) */
  195. pskb_trim(skb, skb->len - alen - padlen - 2);
  196. ret = nexthdr[1];
  197. }
  198. skb->h.raw = __skb_pull(skb, sizeof(*esph) + esp->conf.ivlen) - hdr_len;
  199. out:
  200. return ret;
  201. }
  202. static u32 esp6_get_max_size(struct xfrm_state *x, int mtu)
  203. {
  204. struct esp_data *esp = x->data;
  205. u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
  206. if (x->props.mode == XFRM_MODE_TUNNEL) {
  207. mtu = ALIGN(mtu + 2, blksize);
  208. } else {
  209. /* The worst case. */
  210. u32 padsize = ((blksize - 1) & 7) + 1;
  211. mtu = ALIGN(mtu + 2, padsize) + blksize - padsize;
  212. }
  213. if (esp->conf.padlen)
  214. mtu = ALIGN(mtu, esp->conf.padlen);
  215. return mtu + x->props.header_len + esp->auth.icv_trunc_len;
  216. }
  217. static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
  218. int type, int code, int offset, __be32 info)
  219. {
  220. struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
  221. struct ipv6_esp_hdr *esph = (struct ipv6_esp_hdr*)(skb->data+offset);
  222. struct xfrm_state *x;
  223. if (type != ICMPV6_DEST_UNREACH &&
  224. type != ICMPV6_PKT_TOOBIG)
  225. return;
  226. x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET6);
  227. if (!x)
  228. return;
  229. printk(KERN_DEBUG "pmtu discovery on SA ESP/%08x/" NIP6_FMT "\n",
  230. ntohl(esph->spi), NIP6(iph->daddr));
  231. xfrm_state_put(x);
  232. }
  233. static void esp6_destroy(struct xfrm_state *x)
  234. {
  235. struct esp_data *esp = x->data;
  236. if (!esp)
  237. return;
  238. crypto_free_blkcipher(esp->conf.tfm);
  239. esp->conf.tfm = NULL;
  240. kfree(esp->conf.ivec);
  241. esp->conf.ivec = NULL;
  242. crypto_free_hash(esp->auth.tfm);
  243. esp->auth.tfm = NULL;
  244. kfree(esp->auth.work_icv);
  245. esp->auth.work_icv = NULL;
  246. kfree(esp);
  247. }
  248. static int esp6_init_state(struct xfrm_state *x)
  249. {
  250. struct esp_data *esp = NULL;
  251. struct crypto_blkcipher *tfm;
  252. /* null auth and encryption can have zero length keys */
  253. if (x->aalg) {
  254. if (x->aalg->alg_key_len > 512)
  255. goto error;
  256. }
  257. if (x->ealg == NULL)
  258. goto error;
  259. if (x->encap)
  260. goto error;
  261. esp = kzalloc(sizeof(*esp), GFP_KERNEL);
  262. if (esp == NULL)
  263. return -ENOMEM;
  264. if (x->aalg) {
  265. struct xfrm_algo_desc *aalg_desc;
  266. struct crypto_hash *hash;
  267. esp->auth.key = x->aalg->alg_key;
  268. esp->auth.key_len = (x->aalg->alg_key_len+7)/8;
  269. hash = crypto_alloc_hash(x->aalg->alg_name, 0,
  270. CRYPTO_ALG_ASYNC);
  271. if (IS_ERR(hash))
  272. goto error;
  273. esp->auth.tfm = hash;
  274. if (crypto_hash_setkey(hash, esp->auth.key, esp->auth.key_len))
  275. goto error;
  276. aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
  277. BUG_ON(!aalg_desc);
  278. if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
  279. crypto_hash_digestsize(hash)) {
  280. NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",
  281. x->aalg->alg_name,
  282. crypto_hash_digestsize(hash),
  283. aalg_desc->uinfo.auth.icv_fullbits/8);
  284. goto error;
  285. }
  286. esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
  287. esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
  288. esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL);
  289. if (!esp->auth.work_icv)
  290. goto error;
  291. }
  292. esp->conf.key = x->ealg->alg_key;
  293. esp->conf.key_len = (x->ealg->alg_key_len+7)/8;
  294. tfm = crypto_alloc_blkcipher(x->ealg->alg_name, 0, CRYPTO_ALG_ASYNC);
  295. if (IS_ERR(tfm))
  296. goto error;
  297. esp->conf.tfm = tfm;
  298. esp->conf.ivlen = crypto_blkcipher_ivsize(tfm);
  299. esp->conf.padlen = 0;
  300. if (esp->conf.ivlen) {
  301. esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL);
  302. if (unlikely(esp->conf.ivec == NULL))
  303. goto error;
  304. esp->conf.ivinitted = 0;
  305. }
  306. if (crypto_blkcipher_setkey(tfm, esp->conf.key, esp->conf.key_len))
  307. goto error;
  308. x->props.header_len = sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen;
  309. if (x->props.mode == XFRM_MODE_TUNNEL)
  310. x->props.header_len += sizeof(struct ipv6hdr);
  311. x->data = esp;
  312. return 0;
  313. error:
  314. x->data = esp;
  315. esp6_destroy(x);
  316. x->data = NULL;
  317. return -EINVAL;
  318. }
  319. static struct xfrm_type esp6_type =
  320. {
  321. .description = "ESP6",
  322. .owner = THIS_MODULE,
  323. .proto = IPPROTO_ESP,
  324. .init_state = esp6_init_state,
  325. .destructor = esp6_destroy,
  326. .get_max_size = esp6_get_max_size,
  327. .input = esp6_input,
  328. .output = esp6_output,
  329. .hdr_offset = xfrm6_find_1stfragopt,
  330. };
  331. static struct inet6_protocol esp6_protocol = {
  332. .handler = xfrm6_rcv,
  333. .err_handler = esp6_err,
  334. .flags = INET6_PROTO_NOPOLICY,
  335. };
  336. static int __init esp6_init(void)
  337. {
  338. if (xfrm_register_type(&esp6_type, AF_INET6) < 0) {
  339. printk(KERN_INFO "ipv6 esp init: can't add xfrm type\n");
  340. return -EAGAIN;
  341. }
  342. if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) {
  343. printk(KERN_INFO "ipv6 esp init: can't add protocol\n");
  344. xfrm_unregister_type(&esp6_type, AF_INET6);
  345. return -EAGAIN;
  346. }
  347. return 0;
  348. }
  349. static void __exit esp6_fini(void)
  350. {
  351. if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0)
  352. printk(KERN_INFO "ipv6 esp close: can't remove protocol\n");
  353. if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0)
  354. printk(KERN_INFO "ipv6 esp close: can't remove xfrm type\n");
  355. }
  356. module_init(esp6_init);
  357. module_exit(esp6_fini);
  358. MODULE_LICENSE("GPL");