1 // SPDX-License-Identifier: GPL-2.0-only
2 #define pr_fmt(fmt) "IPsec: " fmt
3
4 #include <crypto/algapi.h>
5 #include <crypto/hash.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
18 struct 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
ah_alloc_tmp(struct crypto_ahash * ahash,int nfrags,unsigned int size)25 static 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 (crypto_ahash_alignmask(ahash) &
32 ~(crypto_tfm_ctx_alignment() - 1));
33
34 len = ALIGN(len, crypto_tfm_ctx_alignment());
35
36 len += sizeof(struct ahash_request) + crypto_ahash_reqsize(ahash);
37 len = ALIGN(len, __alignof__(struct scatterlist));
38
39 len += sizeof(struct scatterlist) * nfrags;
40
41 return kmalloc(len, GFP_ATOMIC);
42 }
43
ah_tmp_auth(void * tmp,unsigned int offset)44 static inline u8 *ah_tmp_auth(void *tmp, unsigned int offset)
45 {
46 return tmp + offset;
47 }
48
ah_tmp_icv(struct crypto_ahash * ahash,void * tmp,unsigned int offset)49 static inline u8 *ah_tmp_icv(struct crypto_ahash *ahash, void *tmp,
50 unsigned int offset)
51 {
52 return PTR_ALIGN((u8 *)tmp + offset, crypto_ahash_alignmask(ahash) + 1);
53 }
54
ah_tmp_req(struct crypto_ahash * ahash,u8 * icv)55 static inline struct ahash_request *ah_tmp_req(struct crypto_ahash *ahash,
56 u8 *icv)
57 {
58 struct ahash_request *req;
59
60 req = (void *)PTR_ALIGN(icv + crypto_ahash_digestsize(ahash),
61 crypto_tfm_ctx_alignment());
62
63 ahash_request_set_tfm(req, ahash);
64
65 return req;
66 }
67
ah_req_sg(struct crypto_ahash * ahash,struct ahash_request * req)68 static inline struct scatterlist *ah_req_sg(struct crypto_ahash *ahash,
69 struct ahash_request *req)
70 {
71 return (void *)ALIGN((unsigned long)(req + 1) +
72 crypto_ahash_reqsize(ahash),
73 __alignof__(struct scatterlist));
74 }
75
76 /* Clear mutable options and find final destination to substitute
77 * into IP header for icv calculation. Options are already checked
78 * for validity, so paranoia is not required. */
79
ip_clear_mutable_options(const struct iphdr * iph,__be32 * daddr)80 static int ip_clear_mutable_options(const struct iphdr *iph, __be32 *daddr)
81 {
82 unsigned char *optptr = (unsigned char *)(iph+1);
83 int l = iph->ihl*4 - sizeof(struct iphdr);
84 int optlen;
85
86 while (l > 0) {
87 switch (*optptr) {
88 case IPOPT_END:
89 return 0;
90 case IPOPT_NOOP:
91 l--;
92 optptr++;
93 continue;
94 }
95 optlen = optptr[1];
96 if (optlen<2 || optlen>l)
97 return -EINVAL;
98 switch (*optptr) {
99 case IPOPT_SEC:
100 case 0x85: /* Some "Extended Security" crap. */
101 case IPOPT_CIPSO:
102 case IPOPT_RA:
103 case 0x80|21: /* RFC1770 */
104 break;
105 case IPOPT_LSRR:
106 case IPOPT_SSRR:
107 if (optlen < 6)
108 return -EINVAL;
109 memcpy(daddr, optptr+optlen-4, 4);
110 fallthrough;
111 default:
112 memset(optptr, 0, optlen);
113 }
114 l -= optlen;
115 optptr += optlen;
116 }
117 return 0;
118 }
119
ah_output_done(struct crypto_async_request * base,int err)120 static void ah_output_done(struct crypto_async_request *base, int err)
121 {
122 u8 *icv;
123 struct iphdr *iph;
124 struct sk_buff *skb = base->data;
125 struct xfrm_state *x = skb_dst(skb)->xfrm;
126 struct ah_data *ahp = x->data;
127 struct iphdr *top_iph = ip_hdr(skb);
128 struct ip_auth_hdr *ah = ip_auth_hdr(skb);
129 int ihl = ip_hdrlen(skb);
130
131 iph = AH_SKB_CB(skb)->tmp;
132 icv = ah_tmp_icv(ahp->ahash, iph, ihl);
133 memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
134
135 top_iph->tos = iph->tos;
136 top_iph->ttl = iph->ttl;
137 top_iph->frag_off = iph->frag_off;
138 if (top_iph->ihl != 5) {
139 top_iph->daddr = iph->daddr;
140 memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
141 }
142
143 kfree(AH_SKB_CB(skb)->tmp);
144 xfrm_output_resume(skb, err);
145 }
146
ah_output(struct xfrm_state * x,struct sk_buff * skb)147 static int ah_output(struct xfrm_state *x, struct sk_buff *skb)
148 {
149 int err;
150 int nfrags;
151 int ihl;
152 u8 *icv;
153 struct sk_buff *trailer;
154 struct crypto_ahash *ahash;
155 struct ahash_request *req;
156 struct scatterlist *sg;
157 struct iphdr *iph, *top_iph;
158 struct ip_auth_hdr *ah;
159 struct ah_data *ahp;
160 int seqhi_len = 0;
161 __be32 *seqhi;
162 int sglists = 0;
163 struct scatterlist *seqhisg;
164
165 ahp = x->data;
166 ahash = ahp->ahash;
167
168 if ((err = skb_cow_data(skb, 0, &trailer)) < 0)
169 goto out;
170 nfrags = err;
171
172 skb_push(skb, -skb_network_offset(skb));
173 ah = ip_auth_hdr(skb);
174 ihl = ip_hdrlen(skb);
175
176 if (x->props.flags & XFRM_STATE_ESN) {
177 sglists = 1;
178 seqhi_len = sizeof(*seqhi);
179 }
180 err = -ENOMEM;
181 iph = ah_alloc_tmp(ahash, nfrags + sglists, ihl + seqhi_len);
182 if (!iph)
183 goto out;
184 seqhi = (__be32 *)((char *)iph + ihl);
185 icv = ah_tmp_icv(ahash, seqhi, seqhi_len);
186 req = ah_tmp_req(ahash, icv);
187 sg = ah_req_sg(ahash, req);
188 seqhisg = sg + nfrags;
189
190 memset(ah->auth_data, 0, ahp->icv_trunc_len);
191
192 top_iph = ip_hdr(skb);
193
194 iph->tos = top_iph->tos;
195 iph->ttl = top_iph->ttl;
196 iph->frag_off = top_iph->frag_off;
197
198 if (top_iph->ihl != 5) {
199 iph->daddr = top_iph->daddr;
200 memcpy(iph+1, top_iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
201 err = ip_clear_mutable_options(top_iph, &top_iph->daddr);
202 if (err)
203 goto out_free;
204 }
205
206 ah->nexthdr = *skb_mac_header(skb);
207 *skb_mac_header(skb) = IPPROTO_AH;
208
209 top_iph->tos = 0;
210 top_iph->tot_len = htons(skb->len);
211 top_iph->frag_off = 0;
212 top_iph->ttl = 0;
213 top_iph->check = 0;
214
215 if (x->props.flags & XFRM_STATE_ALIGN4)
216 ah->hdrlen = (XFRM_ALIGN4(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2;
217 else
218 ah->hdrlen = (XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2;
219
220 ah->reserved = 0;
221 ah->spi = x->id.spi;
222 ah->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
223
224 sg_init_table(sg, nfrags + sglists);
225 err = skb_to_sgvec_nomark(skb, sg, 0, skb->len);
226 if (unlikely(err < 0))
227 goto out_free;
228
229 if (x->props.flags & XFRM_STATE_ESN) {
230 /* Attach seqhi sg right after packet payload */
231 *seqhi = htonl(XFRM_SKB_CB(skb)->seq.output.hi);
232 sg_set_buf(seqhisg, seqhi, seqhi_len);
233 }
234 ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len);
235 ahash_request_set_callback(req, 0, ah_output_done, skb);
236
237 AH_SKB_CB(skb)->tmp = iph;
238
239 err = crypto_ahash_digest(req);
240 if (err) {
241 if (err == -EINPROGRESS)
242 goto out;
243
244 if (err == -ENOSPC)
245 err = NET_XMIT_DROP;
246 goto out_free;
247 }
248
249 memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
250
251 top_iph->tos = iph->tos;
252 top_iph->ttl = iph->ttl;
253 top_iph->frag_off = iph->frag_off;
254 if (top_iph->ihl != 5) {
255 top_iph->daddr = iph->daddr;
256 memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
257 }
258
259 out_free:
260 kfree(iph);
261 out:
262 return err;
263 }
264
ah_input_done(struct crypto_async_request * base,int err)265 static void ah_input_done(struct crypto_async_request *base, int err)
266 {
267 u8 *auth_data;
268 u8 *icv;
269 struct iphdr *work_iph;
270 struct sk_buff *skb = base->data;
271 struct xfrm_state *x = xfrm_input_state(skb);
272 struct ah_data *ahp = x->data;
273 struct ip_auth_hdr *ah = ip_auth_hdr(skb);
274 int ihl = ip_hdrlen(skb);
275 int ah_hlen = (ah->hdrlen + 2) << 2;
276
277 if (err)
278 goto out;
279
280 work_iph = AH_SKB_CB(skb)->tmp;
281 auth_data = ah_tmp_auth(work_iph, ihl);
282 icv = ah_tmp_icv(ahp->ahash, auth_data, ahp->icv_trunc_len);
283
284 err = crypto_memneq(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG : 0;
285 if (err)
286 goto out;
287
288 err = ah->nexthdr;
289
290 skb->network_header += ah_hlen;
291 memcpy(skb_network_header(skb), work_iph, ihl);
292 __skb_pull(skb, ah_hlen + ihl);
293
294 if (x->props.mode == XFRM_MODE_TUNNEL)
295 skb_reset_transport_header(skb);
296 else
297 skb_set_transport_header(skb, -ihl);
298 out:
299 kfree(AH_SKB_CB(skb)->tmp);
300 xfrm_input_resume(skb, err);
301 }
302
ah_input(struct xfrm_state * x,struct sk_buff * skb)303 static int ah_input(struct xfrm_state *x, struct sk_buff *skb)
304 {
305 int ah_hlen;
306 int ihl;
307 int nexthdr;
308 int nfrags;
309 u8 *auth_data;
310 u8 *icv;
311 struct sk_buff *trailer;
312 struct crypto_ahash *ahash;
313 struct ahash_request *req;
314 struct scatterlist *sg;
315 struct iphdr *iph, *work_iph;
316 struct ip_auth_hdr *ah;
317 struct ah_data *ahp;
318 int err = -ENOMEM;
319 int seqhi_len = 0;
320 __be32 *seqhi;
321 int sglists = 0;
322 struct scatterlist *seqhisg;
323
324 if (!pskb_may_pull(skb, sizeof(*ah)))
325 goto out;
326
327 ah = (struct ip_auth_hdr *)skb->data;
328 ahp = x->data;
329 ahash = ahp->ahash;
330
331 nexthdr = ah->nexthdr;
332 ah_hlen = (ah->hdrlen + 2) << 2;
333
334 if (x->props.flags & XFRM_STATE_ALIGN4) {
335 if (ah_hlen != XFRM_ALIGN4(sizeof(*ah) + ahp->icv_full_len) &&
336 ah_hlen != XFRM_ALIGN4(sizeof(*ah) + ahp->icv_trunc_len))
337 goto out;
338 } else {
339 if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) &&
340 ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len))
341 goto out;
342 }
343
344 if (!pskb_may_pull(skb, ah_hlen))
345 goto out;
346
347 /* We are going to _remove_ AH header to keep sockets happy,
348 * so... Later this can change. */
349 if (skb_unclone(skb, GFP_ATOMIC))
350 goto out;
351
352 skb->ip_summed = CHECKSUM_NONE;
353
354
355 if ((err = skb_cow_data(skb, 0, &trailer)) < 0)
356 goto out;
357 nfrags = err;
358
359 ah = (struct ip_auth_hdr *)skb->data;
360 iph = ip_hdr(skb);
361 ihl = ip_hdrlen(skb);
362
363 if (x->props.flags & XFRM_STATE_ESN) {
364 sglists = 1;
365 seqhi_len = sizeof(*seqhi);
366 }
367
368 work_iph = ah_alloc_tmp(ahash, nfrags + sglists, ihl +
369 ahp->icv_trunc_len + seqhi_len);
370 if (!work_iph) {
371 err = -ENOMEM;
372 goto out;
373 }
374
375 seqhi = (__be32 *)((char *)work_iph + ihl);
376 auth_data = ah_tmp_auth(seqhi, seqhi_len);
377 icv = ah_tmp_icv(ahash, auth_data, ahp->icv_trunc_len);
378 req = ah_tmp_req(ahash, icv);
379 sg = ah_req_sg(ahash, req);
380 seqhisg = sg + nfrags;
381
382 memcpy(work_iph, iph, ihl);
383 memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
384 memset(ah->auth_data, 0, ahp->icv_trunc_len);
385
386 iph->ttl = 0;
387 iph->tos = 0;
388 iph->frag_off = 0;
389 iph->check = 0;
390 if (ihl > sizeof(*iph)) {
391 __be32 dummy;
392 err = ip_clear_mutable_options(iph, &dummy);
393 if (err)
394 goto out_free;
395 }
396
397 skb_push(skb, ihl);
398
399 sg_init_table(sg, nfrags + sglists);
400 err = skb_to_sgvec_nomark(skb, sg, 0, skb->len);
401 if (unlikely(err < 0))
402 goto out_free;
403
404 if (x->props.flags & XFRM_STATE_ESN) {
405 /* Attach seqhi sg right after packet payload */
406 *seqhi = XFRM_SKB_CB(skb)->seq.input.hi;
407 sg_set_buf(seqhisg, seqhi, seqhi_len);
408 }
409 ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len);
410 ahash_request_set_callback(req, 0, ah_input_done, skb);
411
412 AH_SKB_CB(skb)->tmp = work_iph;
413
414 err = crypto_ahash_digest(req);
415 if (err) {
416 if (err == -EINPROGRESS)
417 goto out;
418
419 goto out_free;
420 }
421
422 err = crypto_memneq(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG : 0;
423 if (err)
424 goto out_free;
425
426 skb->network_header += ah_hlen;
427 memcpy(skb_network_header(skb), work_iph, ihl);
428 __skb_pull(skb, ah_hlen + ihl);
429 if (x->props.mode == XFRM_MODE_TUNNEL)
430 skb_reset_transport_header(skb);
431 else
432 skb_set_transport_header(skb, -ihl);
433
434 err = nexthdr;
435
436 out_free:
437 kfree (work_iph);
438 out:
439 return err;
440 }
441
ah4_err(struct sk_buff * skb,u32 info)442 static int ah4_err(struct sk_buff *skb, u32 info)
443 {
444 struct net *net = dev_net(skb->dev);
445 const struct iphdr *iph = (const struct iphdr *)skb->data;
446 struct ip_auth_hdr *ah = (struct ip_auth_hdr *)(skb->data+(iph->ihl<<2));
447 struct xfrm_state *x;
448
449 switch (icmp_hdr(skb)->type) {
450 case ICMP_DEST_UNREACH:
451 if (icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
452 return 0;
453 case ICMP_REDIRECT:
454 break;
455 default:
456 return 0;
457 }
458
459 x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
460 ah->spi, IPPROTO_AH, AF_INET);
461 if (!x)
462 return 0;
463
464 if (icmp_hdr(skb)->type == ICMP_DEST_UNREACH)
465 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_AH);
466 else
467 ipv4_redirect(skb, net, 0, IPPROTO_AH);
468 xfrm_state_put(x);
469
470 return 0;
471 }
472
ah_init_state(struct xfrm_state * x)473 static int ah_init_state(struct xfrm_state *x)
474 {
475 struct ah_data *ahp = NULL;
476 struct xfrm_algo_desc *aalg_desc;
477 struct crypto_ahash *ahash;
478
479 if (!x->aalg)
480 goto error;
481
482 if (x->encap)
483 goto error;
484
485 ahp = kzalloc(sizeof(*ahp), GFP_KERNEL);
486 if (!ahp)
487 return -ENOMEM;
488
489 ahash = crypto_alloc_ahash(x->aalg->alg_name, 0, 0);
490 if (IS_ERR(ahash))
491 goto error;
492
493 ahp->ahash = ahash;
494 if (crypto_ahash_setkey(ahash, x->aalg->alg_key,
495 (x->aalg->alg_key_len + 7) / 8))
496 goto error;
497
498 /*
499 * Lookup the algorithm description maintained by xfrm_algo,
500 * verify crypto transform properties, and store information
501 * we need for AH processing. This lookup cannot fail here
502 * after a successful crypto_alloc_ahash().
503 */
504 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
505 BUG_ON(!aalg_desc);
506
507 if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
508 crypto_ahash_digestsize(ahash)) {
509 pr_info("%s: %s digestsize %u != %hu\n",
510 __func__, x->aalg->alg_name,
511 crypto_ahash_digestsize(ahash),
512 aalg_desc->uinfo.auth.icv_fullbits / 8);
513 goto error;
514 }
515
516 ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
517 ahp->icv_trunc_len = x->aalg->alg_trunc_len/8;
518
519 if (x->props.flags & XFRM_STATE_ALIGN4)
520 x->props.header_len = XFRM_ALIGN4(sizeof(struct ip_auth_hdr) +
521 ahp->icv_trunc_len);
522 else
523 x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) +
524 ahp->icv_trunc_len);
525 if (x->props.mode == XFRM_MODE_TUNNEL)
526 x->props.header_len += sizeof(struct iphdr);
527 x->data = ahp;
528
529 return 0;
530
531 error:
532 if (ahp) {
533 crypto_free_ahash(ahp->ahash);
534 kfree(ahp);
535 }
536 return -EINVAL;
537 }
538
ah_destroy(struct xfrm_state * x)539 static void ah_destroy(struct xfrm_state *x)
540 {
541 struct ah_data *ahp = x->data;
542
543 if (!ahp)
544 return;
545
546 crypto_free_ahash(ahp->ahash);
547 kfree(ahp);
548 }
549
ah4_rcv_cb(struct sk_buff * skb,int err)550 static int ah4_rcv_cb(struct sk_buff *skb, int err)
551 {
552 return 0;
553 }
554
555 static const struct xfrm_type ah_type =
556 {
557 .description = "AH4",
558 .owner = THIS_MODULE,
559 .proto = IPPROTO_AH,
560 .flags = XFRM_TYPE_REPLAY_PROT,
561 .init_state = ah_init_state,
562 .destructor = ah_destroy,
563 .input = ah_input,
564 .output = ah_output
565 };
566
567 static struct xfrm4_protocol ah4_protocol = {
568 .handler = xfrm4_rcv,
569 .input_handler = xfrm_input,
570 .cb_handler = ah4_rcv_cb,
571 .err_handler = ah4_err,
572 .priority = 0,
573 };
574
ah4_init(void)575 static int __init ah4_init(void)
576 {
577 if (xfrm_register_type(&ah_type, AF_INET) < 0) {
578 pr_info("%s: can't add xfrm type\n", __func__);
579 return -EAGAIN;
580 }
581 if (xfrm4_protocol_register(&ah4_protocol, IPPROTO_AH) < 0) {
582 pr_info("%s: can't add protocol\n", __func__);
583 xfrm_unregister_type(&ah_type, AF_INET);
584 return -EAGAIN;
585 }
586 return 0;
587 }
588
ah4_fini(void)589 static void __exit ah4_fini(void)
590 {
591 if (xfrm4_protocol_deregister(&ah4_protocol, IPPROTO_AH) < 0)
592 pr_info("%s: can't remove protocol\n", __func__);
593 xfrm_unregister_type(&ah_type, AF_INET);
594 }
595
596 module_init(ah4_init);
597 module_exit(ah4_fini);
598 MODULE_LICENSE("GPL");
599 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_AH);
600
