1 // SPDX-License-Identifier: GPL-2.0-only
2 #define pr_fmt(fmt) "IPsec: " fmt
4 #include <crypto/hash.h>
5 #include <crypto/utils.h>
7 #include <linux/module.h>
8 #include <linux/slab.h>
12 #include <linux/crypto.h>
13 #include <linux/pfkeyv2.h>
14 #include <linux/scatterlist.h>
16 #include <net/protocol.h>
19 struct xfrm_skb_cb xfrm;
23 #define AH_SKB_CB(__skb) ((struct ah_skb_cb *)&((__skb)->cb[0]))
25 static void *ah_alloc_tmp(struct crypto_ahash *ahash, int nfrags,
30 len = size + crypto_ahash_digestsize(ahash);
32 len = ALIGN(len, crypto_tfm_ctx_alignment());
34 len += sizeof(struct ahash_request) + crypto_ahash_reqsize(ahash);
35 len = ALIGN(len, __alignof__(struct scatterlist));
37 len += sizeof(struct scatterlist) * nfrags;
39 return kmalloc(len, GFP_ATOMIC);
42 static inline u8 *ah_tmp_auth(void *tmp, unsigned int offset)
47 static inline u8 *ah_tmp_icv(void *tmp, unsigned int offset)
52 static inline struct ahash_request *ah_tmp_req(struct crypto_ahash *ahash,
55 struct ahash_request *req;
57 req = (void *)PTR_ALIGN(icv + crypto_ahash_digestsize(ahash),
58 crypto_tfm_ctx_alignment());
60 ahash_request_set_tfm(req, ahash);
65 static inline struct scatterlist *ah_req_sg(struct crypto_ahash *ahash,
66 struct ahash_request *req)
68 return (void *)ALIGN((unsigned long)(req + 1) +
69 crypto_ahash_reqsize(ahash),
70 __alignof__(struct scatterlist));
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. */
77 static int ip_clear_mutable_options(const struct iphdr *iph, __be32 *daddr)
79 unsigned char *optptr = (unsigned char *)(iph+1);
80 int l = iph->ihl*4 - sizeof(struct iphdr);
93 if (optlen<2 || optlen>l)
97 case 0x85: /* Some "Extended Security" crap. */
100 case 0x80|21: /* RFC1770 */
106 memcpy(daddr, optptr+optlen-4, 4);
109 memset(optptr, 0, optlen);
117 static void ah_output_done(void *data, int err)
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);
128 iph = AH_SKB_CB(skb)->tmp;
129 icv = ah_tmp_icv(iph, ihl);
130 memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
132 top_iph->tos = iph->tos;
133 top_iph->ttl = iph->ttl;
134 top_iph->frag_off = iph->frag_off;
135 if (top_iph->ihl != 5) {
136 top_iph->daddr = iph->daddr;
137 memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
140 kfree(AH_SKB_CB(skb)->tmp);
141 xfrm_output_resume(skb->sk, skb, err);
144 static int ah_output(struct xfrm_state *x, struct sk_buff *skb)
150 struct sk_buff *trailer;
151 struct crypto_ahash *ahash;
152 struct ahash_request *req;
153 struct scatterlist *sg;
154 struct iphdr *iph, *top_iph;
155 struct ip_auth_hdr *ah;
160 struct scatterlist *seqhisg;
165 if ((err = skb_cow_data(skb, 0, &trailer)) < 0)
169 skb_push(skb, -skb_network_offset(skb));
170 ah = ip_auth_hdr(skb);
171 ihl = ip_hdrlen(skb);
173 if (x->props.flags & XFRM_STATE_ESN) {
175 seqhi_len = sizeof(*seqhi);
178 iph = ah_alloc_tmp(ahash, nfrags + sglists, ihl + seqhi_len);
181 seqhi = (__be32 *)((char *)iph + ihl);
182 icv = ah_tmp_icv(seqhi, seqhi_len);
183 req = ah_tmp_req(ahash, icv);
184 sg = ah_req_sg(ahash, req);
185 seqhisg = sg + nfrags;
187 memset(ah->auth_data, 0, ahp->icv_trunc_len);
189 top_iph = ip_hdr(skb);
191 iph->tos = top_iph->tos;
192 iph->ttl = top_iph->ttl;
193 iph->frag_off = top_iph->frag_off;
195 if (top_iph->ihl != 5) {
196 iph->daddr = top_iph->daddr;
197 memcpy(iph+1, top_iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
198 err = ip_clear_mutable_options(top_iph, &top_iph->daddr);
203 ah->nexthdr = *skb_mac_header(skb);
204 *skb_mac_header(skb) = IPPROTO_AH;
207 top_iph->tot_len = htons(skb->len);
208 top_iph->frag_off = 0;
212 if (x->props.flags & XFRM_STATE_ALIGN4)
213 ah->hdrlen = (XFRM_ALIGN4(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2;
215 ah->hdrlen = (XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2;
219 ah->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
221 sg_init_table(sg, nfrags + sglists);
222 err = skb_to_sgvec_nomark(skb, sg, 0, skb->len);
223 if (unlikely(err < 0))
226 if (x->props.flags & XFRM_STATE_ESN) {
227 /* Attach seqhi sg right after packet payload */
228 *seqhi = htonl(XFRM_SKB_CB(skb)->seq.output.hi);
229 sg_set_buf(seqhisg, seqhi, seqhi_len);
231 ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len);
232 ahash_request_set_callback(req, 0, ah_output_done, skb);
234 AH_SKB_CB(skb)->tmp = iph;
236 err = crypto_ahash_digest(req);
238 if (err == -EINPROGRESS)
246 memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
248 top_iph->tos = iph->tos;
249 top_iph->ttl = iph->ttl;
250 top_iph->frag_off = iph->frag_off;
251 if (top_iph->ihl != 5) {
252 top_iph->daddr = iph->daddr;
253 memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
262 static void ah_input_done(void *data, int err)
266 struct iphdr *work_iph;
267 struct sk_buff *skb = data;
268 struct xfrm_state *x = xfrm_input_state(skb);
269 struct ah_data *ahp = x->data;
270 struct ip_auth_hdr *ah = ip_auth_hdr(skb);
271 int ihl = ip_hdrlen(skb);
272 int ah_hlen = (ah->hdrlen + 2) << 2;
277 work_iph = AH_SKB_CB(skb)->tmp;
278 auth_data = ah_tmp_auth(work_iph, ihl);
279 icv = ah_tmp_icv(auth_data, ahp->icv_trunc_len);
281 err = crypto_memneq(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG : 0;
287 skb->network_header += ah_hlen;
288 memcpy(skb_network_header(skb), work_iph, ihl);
289 __skb_pull(skb, ah_hlen + ihl);
291 if (x->props.mode == XFRM_MODE_TUNNEL)
292 skb_reset_transport_header(skb);
294 skb_set_transport_header(skb, -ihl);
296 kfree(AH_SKB_CB(skb)->tmp);
297 xfrm_input_resume(skb, err);
300 static int ah_input(struct xfrm_state *x, struct sk_buff *skb)
308 struct sk_buff *trailer;
309 struct crypto_ahash *ahash;
310 struct ahash_request *req;
311 struct scatterlist *sg;
312 struct iphdr *iph, *work_iph;
313 struct ip_auth_hdr *ah;
319 struct scatterlist *seqhisg;
321 if (!pskb_may_pull(skb, sizeof(*ah)))
324 ah = (struct ip_auth_hdr *)skb->data;
328 nexthdr = ah->nexthdr;
329 ah_hlen = (ah->hdrlen + 2) << 2;
331 if (x->props.flags & XFRM_STATE_ALIGN4) {
332 if (ah_hlen != XFRM_ALIGN4(sizeof(*ah) + ahp->icv_full_len) &&
333 ah_hlen != XFRM_ALIGN4(sizeof(*ah) + ahp->icv_trunc_len))
336 if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) &&
337 ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len))
341 if (!pskb_may_pull(skb, ah_hlen))
344 /* We are going to _remove_ AH header to keep sockets happy,
345 * so... Later this can change. */
346 if (skb_unclone(skb, GFP_ATOMIC))
349 skb->ip_summed = CHECKSUM_NONE;
352 if ((err = skb_cow_data(skb, 0, &trailer)) < 0)
356 ah = (struct ip_auth_hdr *)skb->data;
358 ihl = ip_hdrlen(skb);
360 if (x->props.flags & XFRM_STATE_ESN) {
362 seqhi_len = sizeof(*seqhi);
365 work_iph = ah_alloc_tmp(ahash, nfrags + sglists, ihl +
366 ahp->icv_trunc_len + seqhi_len);
372 seqhi = (__be32 *)((char *)work_iph + ihl);
373 auth_data = ah_tmp_auth(seqhi, seqhi_len);
374 icv = ah_tmp_icv(auth_data, ahp->icv_trunc_len);
375 req = ah_tmp_req(ahash, icv);
376 sg = ah_req_sg(ahash, req);
377 seqhisg = sg + nfrags;
379 memcpy(work_iph, iph, ihl);
380 memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
381 memset(ah->auth_data, 0, ahp->icv_trunc_len);
387 if (ihl > sizeof(*iph)) {
389 err = ip_clear_mutable_options(iph, &dummy);
396 sg_init_table(sg, nfrags + sglists);
397 err = skb_to_sgvec_nomark(skb, sg, 0, skb->len);
398 if (unlikely(err < 0))
401 if (x->props.flags & XFRM_STATE_ESN) {
402 /* Attach seqhi sg right after packet payload */
403 *seqhi = XFRM_SKB_CB(skb)->seq.input.hi;
404 sg_set_buf(seqhisg, seqhi, seqhi_len);
406 ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len);
407 ahash_request_set_callback(req, 0, ah_input_done, skb);
409 AH_SKB_CB(skb)->tmp = work_iph;
411 err = crypto_ahash_digest(req);
413 if (err == -EINPROGRESS)
419 err = crypto_memneq(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG : 0;
423 skb->network_header += ah_hlen;
424 memcpy(skb_network_header(skb), work_iph, ihl);
425 __skb_pull(skb, ah_hlen + ihl);
426 if (x->props.mode == XFRM_MODE_TUNNEL)
427 skb_reset_transport_header(skb);
429 skb_set_transport_header(skb, -ihl);
439 static int ah4_err(struct sk_buff *skb, u32 info)
441 struct net *net = dev_net(skb->dev);
442 const struct iphdr *iph = (const struct iphdr *)skb->data;
443 struct ip_auth_hdr *ah = (struct ip_auth_hdr *)(skb->data+(iph->ihl<<2));
444 struct xfrm_state *x;
446 switch (icmp_hdr(skb)->type) {
447 case ICMP_DEST_UNREACH:
448 if (icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
457 x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
458 ah->spi, IPPROTO_AH, AF_INET);
462 if (icmp_hdr(skb)->type == ICMP_DEST_UNREACH)
463 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_AH);
465 ipv4_redirect(skb, net, 0, IPPROTO_AH);
471 static int ah_init_state(struct xfrm_state *x, struct netlink_ext_ack *extack)
473 struct ah_data *ahp = NULL;
474 struct xfrm_algo_desc *aalg_desc;
475 struct crypto_ahash *ahash;
478 NL_SET_ERR_MSG(extack, "AH requires a state with an AUTH algorithm");
483 NL_SET_ERR_MSG(extack, "AH is not compatible with encapsulation");
487 ahp = kzalloc(sizeof(*ahp), GFP_KERNEL);
491 ahash = crypto_alloc_ahash(x->aalg->alg_name, 0, 0);
493 NL_SET_ERR_MSG(extack, "Kernel was unable to initialize cryptographic operations");
498 if (crypto_ahash_setkey(ahash, x->aalg->alg_key,
499 (x->aalg->alg_key_len + 7) / 8)) {
500 NL_SET_ERR_MSG(extack, "Kernel was unable to initialize cryptographic operations");
505 * Lookup the algorithm description maintained by xfrm_algo,
506 * verify crypto transform properties, and store information
507 * we need for AH processing. This lookup cannot fail here
508 * after a successful crypto_alloc_ahash().
510 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
513 if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
514 crypto_ahash_digestsize(ahash)) {
515 NL_SET_ERR_MSG(extack, "Kernel was unable to initialize cryptographic operations");
519 ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
520 ahp->icv_trunc_len = x->aalg->alg_trunc_len/8;
522 if (x->props.flags & XFRM_STATE_ALIGN4)
523 x->props.header_len = XFRM_ALIGN4(sizeof(struct ip_auth_hdr) +
526 x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) +
528 if (x->props.mode == XFRM_MODE_TUNNEL)
529 x->props.header_len += sizeof(struct iphdr);
536 crypto_free_ahash(ahp->ahash);
542 static void ah_destroy(struct xfrm_state *x)
544 struct ah_data *ahp = x->data;
549 crypto_free_ahash(ahp->ahash);
553 static int ah4_rcv_cb(struct sk_buff *skb, int err)
558 static const struct xfrm_type ah_type =
560 .owner = THIS_MODULE,
562 .flags = XFRM_TYPE_REPLAY_PROT,
563 .init_state = ah_init_state,
564 .destructor = ah_destroy,
569 static struct xfrm4_protocol ah4_protocol = {
570 .handler = xfrm4_rcv,
571 .input_handler = xfrm_input,
572 .cb_handler = ah4_rcv_cb,
573 .err_handler = ah4_err,
577 static int __init ah4_init(void)
579 if (xfrm_register_type(&ah_type, AF_INET) < 0) {
580 pr_info("%s: can't add xfrm type\n", __func__);
583 if (xfrm4_protocol_register(&ah4_protocol, IPPROTO_AH) < 0) {
584 pr_info("%s: can't add protocol\n", __func__);
585 xfrm_unregister_type(&ah_type, AF_INET);
591 static void __exit ah4_fini(void)
593 if (xfrm4_protocol_deregister(&ah4_protocol, IPPROTO_AH) < 0)
594 pr_info("%s: can't remove protocol\n", __func__);
595 xfrm_unregister_type(&ah_type, AF_INET);
598 module_init(ah4_init);
599 module_exit(ah4_fini);
600 MODULE_DESCRIPTION("IPv4 AH transformation library");
601 MODULE_LICENSE("GPL");
602 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_AH);