tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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/* Clear mutable options and find final destination to substitute
73 * into IP header for icv calculation. Options are already checked
74 * for validity, so paranoia is not required. */
75
76static int ip_clear_mutable_options(const 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: /* Some "Extended Security" crap. */
97 case IPOPT_CIPSO:
98 case IPOPT_RA:
99 case 0x80|21: /* RFC1770 */
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 /* Fall through */
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 kfree(AH_SKB_CB(skb)->tmp);
140 xfrm_output_resume(skb, err);
141}
142
143static int ah_output(struct xfrm_state *x, struct sk_buff *skb)
144{
145 int err;
146 int nfrags;
147 int ihl;
148 u8 *icv;
149 struct sk_buff *trailer;
150 struct crypto_ahash *ahash;
151 struct ahash_request *req;
152 struct scatterlist *sg;
153 struct iphdr *iph, *top_iph;
154 struct ip_auth_hdr *ah;
155 struct ah_data *ahp;
156
157 ahp = x->data;
158 ahash = ahp->ahash;
159
160 if ((err = skb_cow_data(skb, 0, &trailer)) < 0)
161 goto out;
162 nfrags = err;
163
164 skb_push(skb, -skb_network_offset(skb));
165 ah = ip_auth_hdr(skb);
166 ihl = ip_hdrlen(skb);
167
168 err = -ENOMEM;
169 iph = ah_alloc_tmp(ahash, nfrags, ihl);
170 if (!iph)
171 goto out;
172
173 icv = ah_tmp_icv(ahash, iph, ihl);
174 req = ah_tmp_req(ahash, icv);
175 sg = ah_req_sg(ahash, req);
176
177 memset(ah->auth_data, 0, ahp->icv_trunc_len);
178
179 top_iph = ip_hdr(skb);
180
181 iph->tos = top_iph->tos;
182 iph->ttl = top_iph->ttl;
183 iph->frag_off = top_iph->frag_off;
184
185 if (top_iph->ihl != 5) {
186 iph->daddr = top_iph->daddr;
187 memcpy(iph+1, top_iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
188 err = ip_clear_mutable_options(top_iph, &top_iph->daddr);
189 if (err)
190 goto out_free;
191 }
192
193 ah->nexthdr = *skb_mac_header(skb);
194 *skb_mac_header(skb) = IPPROTO_AH;
195
196 top_iph->tos = 0;
197 top_iph->tot_len = htons(skb->len);
198 top_iph->frag_off = 0;
199 top_iph->ttl = 0;
200 top_iph->check = 0;
201
202 if (x->props.flags & XFRM_STATE_ALIGN4)
203 ah->hdrlen = (XFRM_ALIGN4(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2;
204 else
205 ah->hdrlen = (XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2;
206
207 ah->reserved = 0;
208 ah->spi = x->id.spi;
209 ah->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
210
211 sg_init_table(sg, nfrags);
212 skb_to_sgvec(skb, sg, 0, skb->len);
213
214 ahash_request_set_crypt(req, sg, icv, skb->len);
215 ahash_request_set_callback(req, 0, ah_output_done, skb);
216
217 AH_SKB_CB(skb)->tmp = iph;
218
219 err = crypto_ahash_digest(req);
220 if (err) {
221 if (err == -EINPROGRESS)
222 goto out;
223
224 if (err == -EBUSY)
225 err = NET_XMIT_DROP;
226 goto out_free;
227 }
228
229 memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
230
231 top_iph->tos = iph->tos;
232 top_iph->ttl = iph->ttl;
233 top_iph->frag_off = iph->frag_off;
234 if (top_iph->ihl != 5) {
235 top_iph->daddr = iph->daddr;
236 memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
237 }
238
239out_free:
240 kfree(iph);
241out:
242 return err;
243}
244
245static void ah_input_done(struct crypto_async_request *base, int err)
246{
247 u8 *auth_data;
248 u8 *icv;
249 struct iphdr *work_iph;
250 struct sk_buff *skb = base->data;
251 struct xfrm_state *x = xfrm_input_state(skb);
252 struct ah_data *ahp = x->data;
253 struct ip_auth_hdr *ah = ip_auth_hdr(skb);
254 int ihl = ip_hdrlen(skb);
255 int ah_hlen = (ah->hdrlen + 2) << 2;
256
257 work_iph = AH_SKB_CB(skb)->tmp;
258 auth_data = ah_tmp_auth(work_iph, ihl);
259 icv = ah_tmp_icv(ahp->ahash, auth_data, ahp->icv_trunc_len);
260
261 err = memcmp(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG: 0;
262 if (err)
263 goto out;
264
265 err = ah->nexthdr;
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);
271out:
272 kfree(AH_SKB_CB(skb)->tmp);
273 xfrm_input_resume(skb, err);
274}
275
276static int ah_input(struct xfrm_state *x, struct sk_buff *skb)
277{
278 int ah_hlen;
279 int ihl;
280 int nexthdr;
281 int nfrags;
282 u8 *auth_data;
283 u8 *icv;
284 struct sk_buff *trailer;
285 struct crypto_ahash *ahash;
286 struct ahash_request *req;
287 struct scatterlist *sg;
288 struct iphdr *iph, *work_iph;
289 struct ip_auth_hdr *ah;
290 struct ah_data *ahp;
291 int err = -ENOMEM;
292
293 if (!pskb_may_pull(skb, sizeof(*ah)))
294 goto out;
295
296 ah = (struct ip_auth_hdr *)skb->data;
297 ahp = x->data;
298 ahash = ahp->ahash;
299
300 nexthdr = ah->nexthdr;
301 ah_hlen = (ah->hdrlen + 2) << 2;
302
303 if (x->props.flags & XFRM_STATE_ALIGN4) {
304 if (ah_hlen != XFRM_ALIGN4(sizeof(*ah) + ahp->icv_full_len) &&
305 ah_hlen != XFRM_ALIGN4(sizeof(*ah) + ahp->icv_trunc_len))
306 goto out;
307 } else {
308 if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) &&
309 ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len))
310 goto out;
311 }
312
313 if (!pskb_may_pull(skb, ah_hlen))
314 goto out;
315
316 /* We are going to _remove_ AH header to keep sockets happy,
317 * so... Later this can change. */
318 if (skb_cloned(skb) &&
319 pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
320 goto out;
321
322 skb->ip_summed = CHECKSUM_NONE;
323
324
325 if ((err = skb_cow_data(skb, 0, &trailer)) < 0)
326 goto out;
327 nfrags = err;
328
329 ah = (struct ip_auth_hdr *)skb->data;
330 iph = ip_hdr(skb);
331 ihl = ip_hdrlen(skb);
332
333 work_iph = ah_alloc_tmp(ahash, nfrags, ihl + ahp->icv_trunc_len);
334 if (!work_iph)
335 goto out;
336
337 auth_data = ah_tmp_auth(work_iph, ihl);
338 icv = ah_tmp_icv(ahash, auth_data, ahp->icv_trunc_len);
339 req = ah_tmp_req(ahash, icv);
340 sg = ah_req_sg(ahash, req);
341
342 memcpy(work_iph, iph, ihl);
343 memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
344 memset(ah->auth_data, 0, ahp->icv_trunc_len);
345
346 iph->ttl = 0;
347 iph->tos = 0;
348 iph->frag_off = 0;
349 iph->check = 0;
350 if (ihl > sizeof(*iph)) {
351 __be32 dummy;
352 err = ip_clear_mutable_options(iph, &dummy);
353 if (err)
354 goto out_free;
355 }
356
357 skb_push(skb, ihl);
358
359 sg_init_table(sg, nfrags);
360 skb_to_sgvec(skb, sg, 0, skb->len);
361
362 ahash_request_set_crypt(req, sg, icv, skb->len);
363 ahash_request_set_callback(req, 0, ah_input_done, skb);
364
365 AH_SKB_CB(skb)->tmp = work_iph;
366
367 err = crypto_ahash_digest(req);
368 if (err) {
369 if (err == -EINPROGRESS)
370 goto out;
371
372 goto out_free;
373 }
374
375 err = memcmp(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG: 0;
376 if (err)
377 goto out_free;
378
379 skb->network_header += ah_hlen;
380 memcpy(skb_network_header(skb), work_iph, ihl);
381 __skb_pull(skb, ah_hlen + ihl);
382 skb_set_transport_header(skb, -ihl);
383
384 err = nexthdr;
385
386out_free:
387 kfree (work_iph);
388out:
389 return err;
390}
391
392static void ah4_err(struct sk_buff *skb, u32 info)
393{
394 struct net *net = dev_net(skb->dev);
395 const struct iphdr *iph = (const struct iphdr *)skb->data;
396 struct ip_auth_hdr *ah = (struct ip_auth_hdr *)(skb->data+(iph->ihl<<2));
397 struct xfrm_state *x;
398
399 if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH ||
400 icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
401 return;
402
403 x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
404 ah->spi, IPPROTO_AH, AF_INET);
405 if (!x)
406 return;
407 printk(KERN_DEBUG "pmtu discovery on SA AH/%08x/%08x\n",
408 ntohl(ah->spi), ntohl(iph->daddr));
409 xfrm_state_put(x);
410}
411
412static int ah_init_state(struct xfrm_state *x)
413{
414 struct ah_data *ahp = NULL;
415 struct xfrm_algo_desc *aalg_desc;
416 struct crypto_ahash *ahash;
417
418 if (!x->aalg)
419 goto error;
420
421 if (x->encap)
422 goto error;
423
424 ahp = kzalloc(sizeof(*ahp), GFP_KERNEL);
425 if (!ahp)
426 return -ENOMEM;
427
428 ahash = crypto_alloc_ahash(x->aalg->alg_name, 0, 0);
429 if (IS_ERR(ahash))
430 goto error;
431
432 ahp->ahash = ahash;
433 if (crypto_ahash_setkey(ahash, x->aalg->alg_key,
434 (x->aalg->alg_key_len + 7) / 8))
435 goto error;
436
437 /*
438 * Lookup the algorithm description maintained by xfrm_algo,
439 * verify crypto transform properties, and store information
440 * we need for AH processing. This lookup cannot fail here
441 * after a successful crypto_alloc_ahash().
442 */
443 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
444 BUG_ON(!aalg_desc);
445
446 if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
447 crypto_ahash_digestsize(ahash)) {
448 printk(KERN_INFO "AH: %s digestsize %u != %hu\n",
449 x->aalg->alg_name, crypto_ahash_digestsize(ahash),
450 aalg_desc->uinfo.auth.icv_fullbits/8);
451 goto error;
452 }
453
454 ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
455 ahp->icv_trunc_len = x->aalg->alg_trunc_len/8;
456
457 BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN);
458
459 if (x->props.flags & XFRM_STATE_ALIGN4)
460 x->props.header_len = XFRM_ALIGN4(sizeof(struct ip_auth_hdr) +
461 ahp->icv_trunc_len);
462 else
463 x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) +
464 ahp->icv_trunc_len);
465 if (x->props.mode == XFRM_MODE_TUNNEL)
466 x->props.header_len += sizeof(struct iphdr);
467 x->data = ahp;
468
469 return 0;
470
471error:
472 if (ahp) {
473 crypto_free_ahash(ahp->ahash);
474 kfree(ahp);
475 }
476 return -EINVAL;
477}
478
479static void ah_destroy(struct xfrm_state *x)
480{
481 struct ah_data *ahp = x->data;
482
483 if (!ahp)
484 return;
485
486 crypto_free_ahash(ahp->ahash);
487 kfree(ahp);
488}
489
490
491static const struct xfrm_type ah_type =
492{
493 .description = "AH4",
494 .owner = THIS_MODULE,
495 .proto = IPPROTO_AH,
496 .flags = XFRM_TYPE_REPLAY_PROT,
497 .init_state = ah_init_state,
498 .destructor = ah_destroy,
499 .input = ah_input,
500 .output = ah_output
501};
502
503static const struct net_protocol ah4_protocol = {
504 .handler = xfrm4_rcv,
505 .err_handler = ah4_err,
506 .no_policy = 1,
507 .netns_ok = 1,
508};
509
510static int __init ah4_init(void)
511{
512 if (xfrm_register_type(&ah_type, AF_INET) < 0) {
513 printk(KERN_INFO "ip ah init: can't add xfrm type\n");
514 return -EAGAIN;
515 }
516 if (inet_add_protocol(&ah4_protocol, IPPROTO_AH) < 0) {
517 printk(KERN_INFO "ip ah init: can't add protocol\n");
518 xfrm_unregister_type(&ah_type, AF_INET);
519 return -EAGAIN;
520 }
521 return 0;
522}
523
524static void __exit ah4_fini(void)
525{
526 if (inet_del_protocol(&ah4_protocol, IPPROTO_AH) < 0)
527 printk(KERN_INFO "ip ah close: can't remove protocol\n");
528 if (xfrm_unregister_type(&ah_type, AF_INET) < 0)
529 printk(KERN_INFO "ip ah close: can't remove xfrm type\n");
530}
531
532module_init(ah4_init);
533module_exit(ah4_fini);
534MODULE_LICENSE("GPL");
535MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_AH);