1#include <crypto/hash.h>
2#include <linux/err.h>
3#include <linux/module.h>
4#include <linux/slab.h>
5#include <net/ip.h>
6#include <net/xfrm.h>
7#include <net/ah.h>
8#include <linux/crypto.h>
9#include <linux/pfkeyv2.h>
10#include <linux/scatterlist.h>
11#include <net/icmp.h>
12#include <net/protocol.h>
13
14struct ah_skb_cb {
15 struct xfrm_skb_cb xfrm;
16 void *tmp;
17};
18
19#define AH_SKB_CB(__skb) ((struct ah_skb_cb *)&((__skb)->cb[0]))
20
21static void *ah_alloc_tmp(struct crypto_ahash *ahash, int nfrags,
22 unsigned int size)
23{
24 unsigned int len;
25
26 len = size + crypto_ahash_digestsize(ahash) +
27 (crypto_ahash_alignmask(ahash) &
28 ~(crypto_tfm_ctx_alignment() - 1));
29
30 len = ALIGN(len, crypto_tfm_ctx_alignment());
31
32 len += sizeof(struct ahash_request) + crypto_ahash_reqsize(ahash);
33 len = ALIGN(len, __alignof__(struct scatterlist));
34
35 len += sizeof(struct scatterlist) * nfrags;
36
37 return kmalloc(len, GFP_ATOMIC);
38}
39
40static inline u8 *ah_tmp_auth(void *tmp, unsigned int offset)
41{
42 return tmp + offset;
43}
44
45static inline u8 *ah_tmp_icv(struct crypto_ahash *ahash, void *tmp,
46 unsigned int offset)
47{
48 return PTR_ALIGN((u8 *)tmp + offset, crypto_ahash_alignmask(ahash) + 1);
49}
50
51static inline struct ahash_request *ah_tmp_req(struct crypto_ahash *ahash,
52 u8 *icv)
53{
54 struct ahash_request *req;
55
56 req = (void *)PTR_ALIGN(icv + crypto_ahash_digestsize(ahash),
57 crypto_tfm_ctx_alignment());
58
59 ahash_request_set_tfm(req, ahash);
60
61 return req;
62}
63
64static inline struct scatterlist *ah_req_sg(struct crypto_ahash *ahash,
65 struct ahash_request *req)
66{
67 return (void *)ALIGN((unsigned long)(req + 1) +
68 crypto_ahash_reqsize(ahash),
69 __alignof__(struct scatterlist));
70}
71
72
73
74
75
76static int ip_clear_mutable_options(struct iphdr *iph, __be32 *daddr)
77{
78 unsigned char * optptr = (unsigned char*)(iph+1);
79 int l = iph->ihl*4 - sizeof(struct iphdr);
80 int optlen;
81
82 while (l > 0) {
83 switch (*optptr) {
84 case IPOPT_END:
85 return 0;
86 case IPOPT_NOOP:
87 l--;
88 optptr++;
89 continue;
90 }
91 optlen = optptr[1];
92 if (optlen<2 || optlen>l)
93 return -EINVAL;
94 switch (*optptr) {
95 case IPOPT_SEC:
96 case 0x85:
97 case IPOPT_CIPSO:
98 case IPOPT_RA:
99 case 0x80|21:
100 break;
101 case IPOPT_LSRR:
102 case IPOPT_SSRR:
103 if (optlen < 6)
104 return -EINVAL;
105 memcpy(daddr, optptr+optlen-4, 4);
106
107 default:
108 memset(optptr, 0, optlen);
109 }
110 l -= optlen;
111 optptr += optlen;
112 }
113 return 0;
114}
115
116static void ah_output_done(struct crypto_async_request *base, int err)
117{
118 u8 *icv;
119 struct iphdr *iph;
120 struct sk_buff *skb = base->data;
121 struct xfrm_state *x = skb_dst(skb)->xfrm;
122 struct ah_data *ahp = x->data;
123 struct iphdr *top_iph = ip_hdr(skb);
124 struct ip_auth_hdr *ah = ip_auth_hdr(skb);
125 int ihl = ip_hdrlen(skb);
126
127 iph = AH_SKB_CB(skb)->tmp;
128 icv = ah_tmp_icv(ahp->ahash, iph, ihl);
129 memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
130
131 top_iph->tos = iph->tos;
132 top_iph->ttl = iph->ttl;
133 top_iph->frag_off = iph->frag_off;
134 if (top_iph->ihl != 5) {
135 top_iph->daddr = iph->daddr;
136 memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
137 }
138
139 err = ah->nexthdr;
140
141 kfree(AH_SKB_CB(skb)->tmp);
142 xfrm_output_resume(skb, err);
143}
144
145static int ah_output(struct xfrm_state *x, struct sk_buff *skb)
146{
147 int err;
148 int nfrags;
149 int ihl;
150 u8 *icv;
151 struct sk_buff *trailer;
152 struct crypto_ahash *ahash;
153 struct ahash_request *req;
154 struct scatterlist *sg;
155 struct iphdr *iph, *top_iph;
156 struct ip_auth_hdr *ah;
157 struct ah_data *ahp;
158
159 ahp = x->data;
160 ahash = ahp->ahash;
161
162 if ((err = skb_cow_data(skb, 0, &trailer)) < 0)
163 goto out;
164 nfrags = err;
165
166 skb_push(skb, -skb_network_offset(skb));
167 ah = ip_auth_hdr(skb);
168 ihl = ip_hdrlen(skb);
169
170 err = -ENOMEM;
171 iph = ah_alloc_tmp(ahash, nfrags, ihl);
172 if (!iph)
173 goto out;
174
175 icv = ah_tmp_icv(ahash, iph, ihl);
176 req = ah_tmp_req(ahash, icv);
177 sg = ah_req_sg(ahash, req);
178
179 memset(ah->auth_data, 0, ahp->icv_trunc_len);
180
181 top_iph = ip_hdr(skb);
182
183 iph->tos = top_iph->tos;
184 iph->ttl = top_iph->ttl;
185 iph->frag_off = top_iph->frag_off;
186
187 if (top_iph->ihl != 5) {
188 iph->daddr = top_iph->daddr;
189 memcpy(iph+1, top_iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
190 err = ip_clear_mutable_options(top_iph, &top_iph->daddr);
191 if (err)
192 goto out_free;
193 }
194
195 ah->nexthdr = *skb_mac_header(skb);
196 *skb_mac_header(skb) = IPPROTO_AH;
197
198 top_iph->tos = 0;
199 top_iph->tot_len = htons(skb->len);
200 top_iph->frag_off = 0;
201 top_iph->ttl = 0;
202 top_iph->check = 0;
203
204 if (x->props.flags & XFRM_STATE_ALIGN4)
205 ah->hdrlen = (XFRM_ALIGN4(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2;
206 else
207 ah->hdrlen = (XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2;
208
209 ah->reserved = 0;
210 ah->spi = x->id.spi;
211 ah->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
212
213 sg_init_table(sg, nfrags);
214 skb_to_sgvec(skb, sg, 0, skb->len);
215
216 ahash_request_set_crypt(req, sg, icv, skb->len);
217 ahash_request_set_callback(req, 0, ah_output_done, skb);
218
219 AH_SKB_CB(skb)->tmp = iph;
220
221 err = crypto_ahash_digest(req);
222 if (err) {
223 if (err == -EINPROGRESS)
224 goto out;
225
226 if (err == -EBUSY)
227 err = NET_XMIT_DROP;
228 goto out_free;
229 }
230
231 memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
232
233 top_iph->tos = iph->tos;
234 top_iph->ttl = iph->ttl;
235 top_iph->frag_off = iph->frag_off;
236 if (top_iph->ihl != 5) {
237 top_iph->daddr = iph->daddr;
238 memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
239 }
240
241out_free:
242 kfree(iph);
243out:
244 return err;
245}
246
247static void ah_input_done(struct crypto_async_request *base, int err)
248{
249 u8 *auth_data;
250 u8 *icv;
251 struct iphdr *work_iph;
252 struct sk_buff *skb = base->data;
253 struct xfrm_state *x = xfrm_input_state(skb);
254 struct ah_data *ahp = x->data;
255 struct ip_auth_hdr *ah = ip_auth_hdr(skb);
256 int ihl = ip_hdrlen(skb);
257 int ah_hlen = (ah->hdrlen + 2) << 2;
258
259 work_iph = AH_SKB_CB(skb)->tmp;
260 auth_data = ah_tmp_auth(work_iph, ihl);
261 icv = ah_tmp_icv(ahp->ahash, auth_data, ahp->icv_trunc_len);
262
263 err = memcmp(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG: 0;
264 if (err)
265 goto out;
266
267 skb->network_header += ah_hlen;
268 memcpy(skb_network_header(skb), work_iph, ihl);
269 __skb_pull(skb, ah_hlen + ihl);
270 skb_set_transport_header(skb, -ihl);
271
272 err = ah->nexthdr;
273out:
274 kfree(AH_SKB_CB(skb)->tmp);
275 xfrm_input_resume(skb, err);
276}
277
278static int ah_input(struct xfrm_state *x, struct sk_buff *skb)
279{
280 int ah_hlen;
281 int ihl;
282 int nexthdr;
283 int nfrags;
284 u8 *auth_data;
285 u8 *icv;
286 struct sk_buff *trailer;
287 struct crypto_ahash *ahash;
288 struct ahash_request *req;
289 struct scatterlist *sg;
290 struct iphdr *iph, *work_iph;
291 struct ip_auth_hdr *ah;
292 struct ah_data *ahp;
293 int err = -ENOMEM;
294
295 if (!pskb_may_pull(skb, sizeof(*ah)))
296 goto out;
297
298 ah = (struct ip_auth_hdr *)skb->data;
299 ahp = x->data;
300 ahash = ahp->ahash;
301
302 nexthdr = ah->nexthdr;
303 ah_hlen = (ah->hdrlen + 2) << 2;
304
305 if (x->props.flags & XFRM_STATE_ALIGN4) {
306 if (ah_hlen != XFRM_ALIGN4(sizeof(*ah) + ahp->icv_full_len) &&
307 ah_hlen != XFRM_ALIGN4(sizeof(*ah) + ahp->icv_trunc_len))
308 goto out;
309 } else {
310 if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) &&
311 ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len))
312 goto out;
313 }
314
315 if (!pskb_may_pull(skb, ah_hlen))
316 goto out;
317
318
319
320 if (skb_cloned(skb) &&
321 pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
322 goto out;
323
324 skb->ip_summed = CHECKSUM_NONE;
325
326
327 if ((err = skb_cow_data(skb, 0, &trailer)) < 0)
328 goto out;
329 nfrags = err;
330
331 ah = (struct ip_auth_hdr *)skb->data;
332 iph = ip_hdr(skb);
333 ihl = ip_hdrlen(skb);
334
335 work_iph = ah_alloc_tmp(ahash, nfrags, ihl + ahp->icv_trunc_len);
336 if (!work_iph)
337 goto out;
338
339 auth_data = ah_tmp_auth(work_iph, ihl);
340 icv = ah_tmp_icv(ahash, auth_data, ahp->icv_trunc_len);
341 req = ah_tmp_req(ahash, icv);
342 sg = ah_req_sg(ahash, req);
343
344 memcpy(work_iph, iph, ihl);
345 memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
346 memset(ah->auth_data, 0, ahp->icv_trunc_len);
347
348 iph->ttl = 0;
349 iph->tos = 0;
350 iph->frag_off = 0;
351 iph->check = 0;
352 if (ihl > sizeof(*iph)) {
353 __be32 dummy;
354 err = ip_clear_mutable_options(iph, &dummy);
355 if (err)
356 goto out_free;
357 }
358
359 skb_push(skb, ihl);
360
361 sg_init_table(sg, nfrags);
362 skb_to_sgvec(skb, sg, 0, skb->len);
363
364 ahash_request_set_crypt(req, sg, icv, skb->len);
365 ahash_request_set_callback(req, 0, ah_input_done, skb);
366
367 AH_SKB_CB(skb)->tmp = work_iph;
368
369 err = crypto_ahash_digest(req);
370 if (err) {
371 if (err == -EINPROGRESS)
372 goto out;
373
374 if (err == -EBUSY)
375 err = NET_XMIT_DROP;
376 goto out_free;
377 }
378
379 err = memcmp(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG: 0;
380 if (err)
381 goto out_free;
382
383 skb->network_header += ah_hlen;
384 memcpy(skb_network_header(skb), work_iph, ihl);
385 __skb_pull(skb, ah_hlen + ihl);
386 skb_set_transport_header(skb, -ihl);
387
388 err = nexthdr;
389
390out_free:
391 kfree (work_iph);
392out:
393 return err;
394}
395
396static void ah4_err(struct sk_buff *skb, u32 info)
397{
398 struct net *net = dev_net(skb->dev);
399 struct iphdr *iph = (struct iphdr *)skb->data;
400 struct ip_auth_hdr *ah = (struct ip_auth_hdr *)(skb->data+(iph->ihl<<2));
401 struct xfrm_state *x;
402
403 if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH ||
404 icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
405 return;
406
407 x = xfrm_state_lookup(net, skb->mark, (xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET);
408 if (!x)
409 return;
410 printk(KERN_DEBUG "pmtu discovery on SA AH/%08x/%08x\n",
411 ntohl(ah->spi), ntohl(iph->daddr));
412 xfrm_state_put(x);
413}
414
415static int ah_init_state(struct xfrm_state *x)
416{
417 struct ah_data *ahp = NULL;
418 struct xfrm_algo_desc *aalg_desc;
419 struct crypto_ahash *ahash;
420
421 if (!x->aalg)
422 goto error;
423
424 if (x->encap)
425 goto error;
426
427 ahp = kzalloc(sizeof(*ahp), GFP_KERNEL);
428 if (!ahp)
429 return -ENOMEM;
430
431 ahash = crypto_alloc_ahash(x->aalg->alg_name, 0, 0);
432 if (IS_ERR(ahash))
433 goto error;
434
435 ahp->ahash = ahash;
436 if (crypto_ahash_setkey(ahash, x->aalg->alg_key,
437 (x->aalg->alg_key_len + 7) / 8))
438 goto error;
439
440
441
442
443
444
445
446 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
447 BUG_ON(!aalg_desc);
448
449 if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
450 crypto_ahash_digestsize(ahash)) {
451 printk(KERN_INFO "AH: %s digestsize %u != %hu\n",
452 x->aalg->alg_name, crypto_ahash_digestsize(ahash),
453 aalg_desc->uinfo.auth.icv_fullbits/8);
454 goto error;
455 }
456
457 ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
458 ahp->icv_trunc_len = x->aalg->alg_trunc_len/8;
459
460 BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN);
461
462 if (x->props.flags & XFRM_STATE_ALIGN4)
463 x->props.header_len = XFRM_ALIGN4(sizeof(struct ip_auth_hdr) +
464 ahp->icv_trunc_len);
465 else
466 x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) +
467 ahp->icv_trunc_len);
468 if (x->props.mode == XFRM_MODE_TUNNEL)
469 x->props.header_len += sizeof(struct iphdr);
470 x->data = ahp;
471
472 return 0;
473
474error:
475 if (ahp) {
476 crypto_free_ahash(ahp->ahash);
477 kfree(ahp);
478 }
479 return -EINVAL;
480}
481
482static void ah_destroy(struct xfrm_state *x)
483{
484 struct ah_data *ahp = x->data;
485
486 if (!ahp)
487 return;
488
489 crypto_free_ahash(ahp->ahash);
490 kfree(ahp);
491}
492
493
494static const struct xfrm_type ah_type =
495{
496 .description = "AH4",
497 .owner = THIS_MODULE,
498 .proto = IPPROTO_AH,
499 .flags = XFRM_TYPE_REPLAY_PROT,
500 .init_state = ah_init_state,
501 .destructor = ah_destroy,
502 .input = ah_input,
503 .output = ah_output
504};
505
506static const struct net_protocol ah4_protocol = {
507 .handler = xfrm4_rcv,
508 .err_handler = ah4_err,
509 .no_policy = 1,
510 .netns_ok = 1,
511};
512
513static int __init ah4_init(void)
514{
515 if (xfrm_register_type(&ah_type, AF_INET) < 0) {
516 printk(KERN_INFO "ip ah init: can't add xfrm type\n");
517 return -EAGAIN;
518 }
519 if (inet_add_protocol(&ah4_protocol, IPPROTO_AH) < 0) {
520 printk(KERN_INFO "ip ah init: can't add protocol\n");
521 xfrm_unregister_type(&ah_type, AF_INET);
522 return -EAGAIN;
523 }
524 return 0;
525}
526
527static void __exit ah4_fini(void)
528{
529 if (inet_del_protocol(&ah4_protocol, IPPROTO_AH) < 0)
530 printk(KERN_INFO "ip ah close: can't remove protocol\n");
531 if (xfrm_unregister_type(&ah_type, AF_INET) < 0)
532 printk(KERN_INFO "ip ah close: can't remove xfrm type\n");
533}
534
535module_init(ah4_init);
536module_exit(ah4_fini);
537MODULE_LICENSE("GPL");
538MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_AH);
539
