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1// SPDX-License-Identifier: GPL-2.0-only
2#define pr_fmt(fmt) "IPsec: " fmt
3
4#include <crypto/hash.h>
5#include <crypto/utils.h>
6#include <linux/err.h>
7#include <linux/module.h>
8#include <linux/slab.h>
9#include <net/ip.h>
10#include <net/xfrm.h>
11#include <net/ah.h>
12#include <linux/crypto.h>
13#include <linux/pfkeyv2.h>
14#include <linux/scatterlist.h>
15#include <net/icmp.h>
16#include <net/protocol.h>
17
18struct ah_skb_cb {
19 struct xfrm_skb_cb xfrm;
20 void *tmp;
21};
22
23#define AH_SKB_CB(__skb) ((struct ah_skb_cb *)&((__skb)->cb[0]))
24
25static void *ah_alloc_tmp(struct crypto_ahash *ahash, int nfrags,
26 unsigned int size)
27{
28 unsigned int len;
29
30 len = size + crypto_ahash_digestsize(ahash);
31
32 len = ALIGN(len, crypto_tfm_ctx_alignment());
33
34 len += sizeof(struct ahash_request) + crypto_ahash_reqsize(ahash);
35 len = ALIGN(len, __alignof__(struct scatterlist));
36
37 len += sizeof(struct scatterlist) * nfrags;
38
39 return kmalloc(len, GFP_ATOMIC);
40}
41
42static inline u8 *ah_tmp_auth(void *tmp, unsigned int offset)
43{
44 return tmp + offset;
45}
46
47static inline u8 *ah_tmp_icv(void *tmp, unsigned int offset)
48{
49 return tmp + offset;
50}
51
52static inline struct ahash_request *ah_tmp_req(struct crypto_ahash *ahash,
53 u8 *icv)
54{
55 struct ahash_request *req;
56
57 req = (void *)PTR_ALIGN(icv + crypto_ahash_digestsize(ahash),
58 crypto_tfm_ctx_alignment());
59
60 ahash_request_set_tfm(req, ahash);
61
62 return req;
63}
64
65static inline struct scatterlist *ah_req_sg(struct crypto_ahash *ahash,
66 struct ahash_request *req)
67{
68 return (void *)ALIGN((unsigned long)(req + 1) +
69 crypto_ahash_reqsize(ahash),
70 __alignof__(struct scatterlist));
71}
72
73/* Clear mutable options and find final destination to substitute
74 * into IP header for icv calculation. Options are already checked
75 * for validity, so paranoia is not required. */
76
77static int ip_clear_mutable_options(const struct iphdr *iph, __be32 *daddr)
78{
79 unsigned char *optptr = (unsigned char *)(iph+1);
80 int l = iph->ihl*4 - sizeof(struct iphdr);
81 int optlen;
82
83 while (l > 0) {
84 switch (*optptr) {
85 case IPOPT_END:
86 return 0;
87 case IPOPT_NOOP:
88 l--;
89 optptr++;
90 continue;
91 }
92 optlen = optptr[1];
93 if (optlen<2 || optlen>l)
94 return -EINVAL;
95 switch (*optptr) {
96 case IPOPT_SEC:
97 case 0x85: /* Some "Extended Security" crap. */
98 case IPOPT_CIPSO:
99 case IPOPT_RA:
100 case 0x80|21: /* RFC1770 */
101 break;
102 case IPOPT_LSRR:
103 case IPOPT_SSRR:
104 if (optlen < 6)
105 return -EINVAL;
106 memcpy(daddr, optptr+optlen-4, 4);
107 fallthrough;
108 default:
109 memset(optptr, 0, optlen);
110 }
111 l -= optlen;
112 optptr += optlen;
113 }
114 return 0;
115}
116
117static void ah_output_done(void *data, int err)
118{
119 u8 *icv;
120 struct iphdr *iph;
121 struct sk_buff *skb = data;
122 struct xfrm_state *x = skb_dst(skb)->xfrm;
123 struct ah_data *ahp = x->data;
124 struct iphdr *top_iph = ip_hdr(skb);
125 struct ip_auth_hdr *ah = ip_auth_hdr(skb);
126 int ihl = ip_hdrlen(skb);
127 int seqhi_len = 0;
128 __be32 *seqhi;
129
130 if (x->props.flags & XFRM_STATE_ESN)
131 seqhi_len = sizeof(*seqhi);
132 iph = AH_SKB_CB(skb)->tmp;
133 seqhi = (__be32 *)((char *)iph + ihl);
134 icv = ah_tmp_icv(seqhi, seqhi_len);
135 memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
136
137 top_iph->tos = iph->tos;
138 top_iph->ttl = iph->ttl;
139 top_iph->frag_off = iph->frag_off;
140 if (top_iph->ihl != 5) {
141 top_iph->daddr = iph->daddr;
142 memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
143 }
144
145 kfree(AH_SKB_CB(skb)->tmp);
146 xfrm_output_resume(skb_to_full_sk(skb), skb, err);
147}
148
149static int ah_output(struct xfrm_state *x, struct sk_buff *skb)
150{
151 int err;
152 int nfrags;
153 int ihl;
154 u8 *icv;
155 struct sk_buff *trailer;
156 struct crypto_ahash *ahash;
157 struct ahash_request *req;
158 struct scatterlist *sg;
159 struct iphdr *iph, *top_iph;
160 struct ip_auth_hdr *ah;
161 struct ah_data *ahp;
162 int seqhi_len = 0;
163 __be32 *seqhi;
164 int sglists = 0;
165 struct scatterlist *seqhisg;
166
167 ahp = x->data;
168 ahash = ahp->ahash;
169
170 if ((err = skb_cow_data(skb, 0, &trailer)) < 0)
171 goto out;
172 nfrags = err;
173
174 skb_push(skb, -skb_network_offset(skb));
175 ah = ip_auth_hdr(skb);
176 ihl = ip_hdrlen(skb);
177
178 if (x->props.flags & XFRM_STATE_ESN) {
179 sglists = 1;
180 seqhi_len = sizeof(*seqhi);
181 }
182 err = -ENOMEM;
183 iph = ah_alloc_tmp(ahash, nfrags + sglists, ihl + seqhi_len);
184 if (!iph)
185 goto out;
186 seqhi = (__be32 *)((char *)iph + ihl);
187 icv = ah_tmp_icv(seqhi, seqhi_len);
188 req = ah_tmp_req(ahash, icv);
189 sg = ah_req_sg(ahash, req);
190 seqhisg = sg + nfrags;
191
192 memset(ah->auth_data, 0, ahp->icv_trunc_len);
193
194 top_iph = ip_hdr(skb);
195
196 iph->tos = top_iph->tos;
197 iph->ttl = top_iph->ttl;
198 iph->frag_off = top_iph->frag_off;
199
200 if (top_iph->ihl != 5) {
201 iph->daddr = top_iph->daddr;
202 memcpy(iph+1, top_iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
203 err = ip_clear_mutable_options(top_iph, &top_iph->daddr);
204 if (err)
205 goto out_free;
206 }
207
208 ah->nexthdr = *skb_mac_header(skb);
209 *skb_mac_header(skb) = IPPROTO_AH;
210
211 top_iph->tos = 0;
212 top_iph->tot_len = htons(skb->len);
213 top_iph->frag_off = 0;
214 top_iph->ttl = 0;
215 top_iph->check = 0;
216
217 if (x->props.flags & XFRM_STATE_ALIGN4)
218 ah->hdrlen = (XFRM_ALIGN4(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2;
219 else
220 ah->hdrlen = (XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2;
221
222 ah->reserved = 0;
223 ah->spi = x->id.spi;
224 ah->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
225
226 sg_init_table(sg, nfrags + sglists);
227 err = skb_to_sgvec_nomark(skb, sg, 0, skb->len);
228 if (unlikely(err < 0))
229 goto out_free;
230
231 if (x->props.flags & XFRM_STATE_ESN) {
232 /* Attach seqhi sg right after packet payload */
233 *seqhi = htonl(XFRM_SKB_CB(skb)->seq.output.hi);
234 sg_set_buf(seqhisg, seqhi, seqhi_len);
235 }
236 ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len);
237 ahash_request_set_callback(req, 0, ah_output_done, skb);
238
239 AH_SKB_CB(skb)->tmp = iph;
240
241 err = crypto_ahash_digest(req);
242 if (err) {
243 if (err == -EINPROGRESS)
244 goto out;
245
246 if (err == -ENOSPC)
247 err = NET_XMIT_DROP;
248 goto out_free;
249 }
250
251 memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
252
253 top_iph->tos = iph->tos;
254 top_iph->ttl = iph->ttl;
255 top_iph->frag_off = iph->frag_off;
256 if (top_iph->ihl != 5) {
257 top_iph->daddr = iph->daddr;
258 memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
259 }
260
261out_free:
262 kfree(iph);
263out:
264 return err;
265}
266
267static void ah_input_done(void *data, int err)
268{
269 u8 *auth_data;
270 u8 *icv;
271 struct iphdr *work_iph;
272 struct sk_buff *skb = data;
273 struct xfrm_state *x = xfrm_input_state(skb);
274 struct ah_data *ahp = x->data;
275 struct ip_auth_hdr *ah = ip_auth_hdr(skb);
276 int ihl = ip_hdrlen(skb);
277 int ah_hlen = (ah->hdrlen + 2) << 2;
278 int seqhi_len = 0;
279 __be32 *seqhi;
280
281 if (err)
282 goto out;
283
284 if (x->props.flags & XFRM_STATE_ESN)
285 seqhi_len = sizeof(*seqhi);
286 work_iph = AH_SKB_CB(skb)->tmp;
287 seqhi = (__be32 *)((char *)work_iph + ihl);
288 auth_data = ah_tmp_auth(seqhi, seqhi_len);
289 icv = ah_tmp_icv(auth_data, ahp->icv_trunc_len);
290
291 err = crypto_memneq(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG : 0;
292 if (err)
293 goto out;
294
295 err = ah->nexthdr;
296
297 skb->network_header += ah_hlen;
298 memcpy(skb_network_header(skb), work_iph, ihl);
299 __skb_pull(skb, ah_hlen + ihl);
300
301 if (x->props.mode == XFRM_MODE_TUNNEL)
302 skb_reset_transport_header(skb);
303 else
304 skb_set_transport_header(skb, -ihl);
305out:
306 kfree(AH_SKB_CB(skb)->tmp);
307 xfrm_input_resume(skb, err);
308}
309
310static int ah_input(struct xfrm_state *x, struct sk_buff *skb)
311{
312 int ah_hlen;
313 int ihl;
314 int nexthdr;
315 int nfrags;
316 u8 *auth_data;
317 u8 *icv;
318 struct sk_buff *trailer;
319 struct crypto_ahash *ahash;
320 struct ahash_request *req;
321 struct scatterlist *sg;
322 struct iphdr *iph, *work_iph;
323 struct ip_auth_hdr *ah;
324 struct ah_data *ahp;
325 int err = -ENOMEM;
326 int seqhi_len = 0;
327 __be32 *seqhi;
328 int sglists = 0;
329 struct scatterlist *seqhisg;
330
331 if (!pskb_may_pull(skb, sizeof(*ah)))
332 goto out;
333
334 ah = (struct ip_auth_hdr *)skb->data;
335 ahp = x->data;
336 ahash = ahp->ahash;
337
338 nexthdr = ah->nexthdr;
339 ah_hlen = (ah->hdrlen + 2) << 2;
340
341 if (x->props.flags & XFRM_STATE_ALIGN4) {
342 if (ah_hlen != XFRM_ALIGN4(sizeof(*ah) + ahp->icv_full_len) &&
343 ah_hlen != XFRM_ALIGN4(sizeof(*ah) + ahp->icv_trunc_len))
344 goto out;
345 } else {
346 if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) &&
347 ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len))
348 goto out;
349 }
350
351 if (!pskb_may_pull(skb, ah_hlen))
352 goto out;
353
354 /* We are going to _remove_ AH header to keep sockets happy,
355 * so... Later this can change. */
356 if (skb_unclone(skb, GFP_ATOMIC))
357 goto out;
358
359 skb->ip_summed = CHECKSUM_NONE;
360
361
362 if ((err = skb_cow_data(skb, 0, &trailer)) < 0)
363 goto out;
364 nfrags = err;
365
366 ah = (struct ip_auth_hdr *)skb->data;
367 iph = ip_hdr(skb);
368 ihl = ip_hdrlen(skb);
369
370 if (x->props.flags & XFRM_STATE_ESN) {
371 sglists = 1;
372 seqhi_len = sizeof(*seqhi);
373 }
374
375 work_iph = ah_alloc_tmp(ahash, nfrags + sglists, ihl +
376 ahp->icv_trunc_len + seqhi_len);
377 if (!work_iph) {
378 err = -ENOMEM;
379 goto out;
380 }
381
382 seqhi = (__be32 *)((char *)work_iph + ihl);
383 auth_data = ah_tmp_auth(seqhi, seqhi_len);
384 icv = ah_tmp_icv(auth_data, ahp->icv_trunc_len);
385 req = ah_tmp_req(ahash, icv);
386 sg = ah_req_sg(ahash, req);
387 seqhisg = sg + nfrags;
388
389 memcpy(work_iph, iph, ihl);
390 memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
391 memset(ah->auth_data, 0, ahp->icv_trunc_len);
392
393 iph->ttl = 0;
394 iph->tos = 0;
395 iph->frag_off = 0;
396 iph->check = 0;
397 if (ihl > sizeof(*iph)) {
398 __be32 dummy;
399 err = ip_clear_mutable_options(iph, &dummy);
400 if (err)
401 goto out_free;
402 }
403
404 skb_push(skb, ihl);
405
406 sg_init_table(sg, nfrags + sglists);
407 err = skb_to_sgvec_nomark(skb, sg, 0, skb->len);
408 if (unlikely(err < 0))
409 goto out_free;
410
411 if (x->props.flags & XFRM_STATE_ESN) {
412 /* Attach seqhi sg right after packet payload */
413 *seqhi = XFRM_SKB_CB(skb)->seq.input.hi;
414 sg_set_buf(seqhisg, seqhi, seqhi_len);
415 }
416 ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len);
417 ahash_request_set_callback(req, 0, ah_input_done, skb);
418
419 AH_SKB_CB(skb)->tmp = work_iph;
420
421 err = crypto_ahash_digest(req);
422 if (err) {
423 if (err == -EINPROGRESS)
424 goto out;
425
426 goto out_free;
427 }
428
429 err = crypto_memneq(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG : 0;
430 if (err)
431 goto out_free;
432
433 skb->network_header += ah_hlen;
434 memcpy(skb_network_header(skb), work_iph, ihl);
435 __skb_pull(skb, ah_hlen + ihl);
436 if (x->props.mode == XFRM_MODE_TUNNEL)
437 skb_reset_transport_header(skb);
438 else
439 skb_set_transport_header(skb, -ihl);
440
441 err = nexthdr;
442
443out_free:
444 kfree (work_iph);
445out:
446 return err;
447}
448
449static int ah4_err(struct sk_buff *skb, u32 info)
450{
451 struct net *net = dev_net(skb->dev);
452 const struct iphdr *iph = (const struct iphdr *)skb->data;
453 struct ip_auth_hdr *ah = (struct ip_auth_hdr *)(skb->data+(iph->ihl<<2));
454 struct xfrm_state *x;
455
456 switch (icmp_hdr(skb)->type) {
457 case ICMP_DEST_UNREACH:
458 if (icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
459 return 0;
460 break;
461 case ICMP_REDIRECT:
462 break;
463 default:
464 return 0;
465 }
466
467 x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
468 ah->spi, IPPROTO_AH, AF_INET);
469 if (!x)
470 return 0;
471
472 if (icmp_hdr(skb)->type == ICMP_DEST_UNREACH)
473 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_AH);
474 else
475 ipv4_redirect(skb, net, 0, IPPROTO_AH);
476 xfrm_state_put(x);
477
478 return 0;
479}
480
481static int ah_init_state(struct xfrm_state *x, struct netlink_ext_ack *extack)
482{
483 struct ah_data *ahp = NULL;
484 struct xfrm_algo_desc *aalg_desc;
485 struct crypto_ahash *ahash;
486
487 if (!x->aalg) {
488 NL_SET_ERR_MSG(extack, "AH requires a state with an AUTH algorithm");
489 goto error;
490 }
491
492 if (x->encap) {
493 NL_SET_ERR_MSG(extack, "AH is not compatible with encapsulation");
494 goto error;
495 }
496
497 ahp = kzalloc_obj(*ahp);
498 if (!ahp)
499 return -ENOMEM;
500
501 ahash = crypto_alloc_ahash(x->aalg->alg_name, 0, 0);
502 if (IS_ERR(ahash)) {
503 NL_SET_ERR_MSG(extack, "Kernel was unable to initialize cryptographic operations");
504 goto error;
505 }
506
507 ahp->ahash = ahash;
508 if (crypto_ahash_setkey(ahash, x->aalg->alg_key,
509 (x->aalg->alg_key_len + 7) / 8)) {
510 NL_SET_ERR_MSG(extack, "Kernel was unable to initialize cryptographic operations");
511 goto error;
512 }
513
514 /*
515 * Lookup the algorithm description maintained by xfrm_algo,
516 * verify crypto transform properties, and store information
517 * we need for AH processing. This lookup cannot fail here
518 * after a successful crypto_alloc_ahash().
519 */
520 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
521 BUG_ON(!aalg_desc);
522
523 if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
524 crypto_ahash_digestsize(ahash)) {
525 NL_SET_ERR_MSG(extack, "Kernel was unable to initialize cryptographic operations");
526 goto error;
527 }
528
529 ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
530 ahp->icv_trunc_len = x->aalg->alg_trunc_len/8;
531
532 if (x->props.flags & XFRM_STATE_ALIGN4)
533 x->props.header_len = XFRM_ALIGN4(sizeof(struct ip_auth_hdr) +
534 ahp->icv_trunc_len);
535 else
536 x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) +
537 ahp->icv_trunc_len);
538 if (x->props.mode == XFRM_MODE_TUNNEL)
539 x->props.header_len += sizeof(struct iphdr);
540 x->data = ahp;
541
542 return 0;
543
544error:
545 if (ahp) {
546 crypto_free_ahash(ahp->ahash);
547 kfree(ahp);
548 }
549 return -EINVAL;
550}
551
552static void ah_destroy(struct xfrm_state *x)
553{
554 struct ah_data *ahp = x->data;
555
556 if (!ahp)
557 return;
558
559 crypto_free_ahash(ahp->ahash);
560 kfree(ahp);
561}
562
563static int ah4_rcv_cb(struct sk_buff *skb, int err)
564{
565 return 0;
566}
567
568static const struct xfrm_type ah_type =
569{
570 .owner = THIS_MODULE,
571 .proto = IPPROTO_AH,
572 .flags = XFRM_TYPE_REPLAY_PROT,
573 .init_state = ah_init_state,
574 .destructor = ah_destroy,
575 .input = ah_input,
576 .output = ah_output
577};
578
579static struct xfrm4_protocol ah4_protocol = {
580 .handler = xfrm4_rcv,
581 .input_handler = xfrm_input,
582 .cb_handler = ah4_rcv_cb,
583 .err_handler = ah4_err,
584 .priority = 0,
585};
586
587static int __init ah4_init(void)
588{
589 if (xfrm_register_type(&ah_type, AF_INET) < 0) {
590 pr_info("%s: can't add xfrm type\n", __func__);
591 return -EAGAIN;
592 }
593 if (xfrm4_protocol_register(&ah4_protocol, IPPROTO_AH) < 0) {
594 pr_info("%s: can't add protocol\n", __func__);
595 xfrm_unregister_type(&ah_type, AF_INET);
596 return -EAGAIN;
597 }
598 return 0;
599}
600
601static void __exit ah4_fini(void)
602{
603 if (xfrm4_protocol_deregister(&ah4_protocol, IPPROTO_AH) < 0)
604 pr_info("%s: can't remove protocol\n", __func__);
605 xfrm_unregister_type(&ah_type, AF_INET);
606}
607
608module_init(ah4_init);
609module_exit(ah4_fini);
610MODULE_DESCRIPTION("IPv4 AH transformation library");
611MODULE_LICENSE("GPL");
612MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_AH);