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TOMOYO Linux Cross Reference
Linux/net/ipv4/ah4.c

Version: ~ [ linux-5.12-rc5 ] ~ [ linux-5.11.11 ] ~ [ linux-5.10.27 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.109 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.184 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.228 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.264 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.264 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.18.140 ] ~ [ linux-3.16.85 ] ~ [ linux-3.14.79 ] ~ [ linux-3.12.74 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 #define pr_fmt(fmt) "IPsec: " fmt
  2 
  3 #include <crypto/hash.h>
  4 #include <linux/err.h>
  5 #include <linux/module.h>
  6 #include <linux/slab.h>
  7 #include <net/ip.h>
  8 #include <net/xfrm.h>
  9 #include <net/ah.h>
 10 #include <linux/crypto.h>
 11 #include <linux/pfkeyv2.h>
 12 #include <linux/scatterlist.h>
 13 #include <net/icmp.h>
 14 #include <net/protocol.h>
 15 
 16 struct ah_skb_cb {
 17         struct xfrm_skb_cb xfrm;
 18         void *tmp;
 19 };
 20 
 21 #define AH_SKB_CB(__skb) ((struct ah_skb_cb *)&((__skb)->cb[0]))
 22 
 23 static void *ah_alloc_tmp(struct crypto_ahash *ahash, int nfrags,
 24                           unsigned int size)
 25 {
 26         unsigned int len;
 27 
 28         len = size + crypto_ahash_digestsize(ahash) +
 29               (crypto_ahash_alignmask(ahash) &
 30                ~(crypto_tfm_ctx_alignment() - 1));
 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 
 42 static inline u8 *ah_tmp_auth(void *tmp, unsigned int offset)
 43 {
 44         return tmp + offset;
 45 }
 46 
 47 static inline u8 *ah_tmp_icv(struct crypto_ahash *ahash, void *tmp,
 48                              unsigned int offset)
 49 {
 50         return PTR_ALIGN((u8 *)tmp + offset, crypto_ahash_alignmask(ahash) + 1);
 51 }
 52 
 53 static inline struct ahash_request *ah_tmp_req(struct crypto_ahash *ahash,
 54                                                u8 *icv)
 55 {
 56         struct ahash_request *req;
 57 
 58         req = (void *)PTR_ALIGN(icv + crypto_ahash_digestsize(ahash),
 59                                 crypto_tfm_ctx_alignment());
 60 
 61         ahash_request_set_tfm(req, ahash);
 62 
 63         return req;
 64 }
 65 
 66 static inline struct scatterlist *ah_req_sg(struct crypto_ahash *ahash,
 67                                              struct ahash_request *req)
 68 {
 69         return (void *)ALIGN((unsigned long)(req + 1) +
 70                              crypto_ahash_reqsize(ahash),
 71                              __alignof__(struct scatterlist));
 72 }
 73 
 74 /* Clear mutable options and find final destination to substitute
 75  * into IP header for icv calculation. Options are already checked
 76  * for validity, so paranoia is not required. */
 77 
 78 static int ip_clear_mutable_options(const struct iphdr *iph, __be32 *daddr)
 79 {
 80         unsigned char *optptr = (unsigned char *)(iph+1);
 81         int  l = iph->ihl*4 - sizeof(struct iphdr);
 82         int  optlen;
 83 
 84         while (l > 0) {
 85                 switch (*optptr) {
 86                 case IPOPT_END:
 87                         return 0;
 88                 case IPOPT_NOOP:
 89                         l--;
 90                         optptr++;
 91                         continue;
 92                 }
 93                 optlen = optptr[1];
 94                 if (optlen<2 || optlen>l)
 95                         return -EINVAL;
 96                 switch (*optptr) {
 97                 case IPOPT_SEC:
 98                 case 0x85:      /* Some "Extended Security" crap. */
 99                 case IPOPT_CIPSO:
100                 case IPOPT_RA:
101                 case 0x80|21:   /* RFC1770 */
102                         break;
103                 case IPOPT_LSRR:
104                 case IPOPT_SSRR:
105                         if (optlen < 6)
106                                 return -EINVAL;
107                         memcpy(daddr, optptr+optlen-4, 4);
108                         /* Fall through */
109                 default:
110                         memset(optptr, 0, optlen);
111                 }
112                 l -= optlen;
113                 optptr += optlen;
114         }
115         return 0;
116 }
117 
118 static void ah_output_done(struct crypto_async_request *base, int err)
119 {
120         u8 *icv;
121         struct iphdr *iph;
122         struct sk_buff *skb = base->data;
123         struct xfrm_state *x = skb_dst(skb)->xfrm;
124         struct ah_data *ahp = x->data;
125         struct iphdr *top_iph = ip_hdr(skb);
126         struct ip_auth_hdr *ah = ip_auth_hdr(skb);
127         int ihl = ip_hdrlen(skb);
128 
129         iph = AH_SKB_CB(skb)->tmp;
130         icv = ah_tmp_icv(ahp->ahash, iph, ihl);
131         memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
132 
133         top_iph->tos = iph->tos;
134         top_iph->ttl = iph->ttl;
135         top_iph->frag_off = iph->frag_off;
136         if (top_iph->ihl != 5) {
137                 top_iph->daddr = iph->daddr;
138                 memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
139         }
140 
141         kfree(AH_SKB_CB(skb)->tmp);
142         xfrm_output_resume(skb, err);
143 }
144 
145 static 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         int seqhi_len = 0;
159         __be32 *seqhi;
160         int sglists = 0;
161         struct scatterlist *seqhisg;
162 
163         ahp = x->data;
164         ahash = ahp->ahash;
165 
166         if ((err = skb_cow_data(skb, 0, &trailer)) < 0)
167                 goto out;
168         nfrags = err;
169 
170         skb_push(skb, -skb_network_offset(skb));
171         ah = ip_auth_hdr(skb);
172         ihl = ip_hdrlen(skb);
173 
174         if (x->props.flags & XFRM_STATE_ESN) {
175                 sglists = 1;
176                 seqhi_len = sizeof(*seqhi);
177         }
178         err = -ENOMEM;
179         iph = ah_alloc_tmp(ahash, nfrags + sglists, ihl + seqhi_len);
180         if (!iph)
181                 goto out;
182         seqhi = (__be32 *)((char *)iph + ihl);
183         icv = ah_tmp_icv(ahash, seqhi, seqhi_len);
184         req = ah_tmp_req(ahash, icv);
185         sg = ah_req_sg(ahash, req);
186         seqhisg = sg + nfrags;
187 
188         memset(ah->auth_data, 0, ahp->icv_trunc_len);
189 
190         top_iph = ip_hdr(skb);
191 
192         iph->tos = top_iph->tos;
193         iph->ttl = top_iph->ttl;
194         iph->frag_off = top_iph->frag_off;
195 
196         if (top_iph->ihl != 5) {
197                 iph->daddr = top_iph->daddr;
198                 memcpy(iph+1, top_iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
199                 err = ip_clear_mutable_options(top_iph, &top_iph->daddr);
200                 if (err)
201                         goto out_free;
202         }
203 
204         ah->nexthdr = *skb_mac_header(skb);
205         *skb_mac_header(skb) = IPPROTO_AH;
206 
207         top_iph->tos = 0;
208         top_iph->tot_len = htons(skb->len);
209         top_iph->frag_off = 0;
210         top_iph->ttl = 0;
211         top_iph->check = 0;
212 
213         if (x->props.flags & XFRM_STATE_ALIGN4)
214                 ah->hdrlen  = (XFRM_ALIGN4(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2;
215         else
216                 ah->hdrlen  = (XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2;
217 
218         ah->reserved = 0;
219         ah->spi = x->id.spi;
220         ah->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
221 
222         sg_init_table(sg, nfrags + sglists);
223         skb_to_sgvec_nomark(skb, sg, 0, skb->len);
224 
225         if (x->props.flags & XFRM_STATE_ESN) {
226                 /* Attach seqhi sg right after packet payload */
227                 *seqhi = htonl(XFRM_SKB_CB(skb)->seq.output.hi);
228                 sg_set_buf(seqhisg, seqhi, seqhi_len);
229         }
230         ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len);
231         ahash_request_set_callback(req, 0, ah_output_done, skb);
232 
233         AH_SKB_CB(skb)->tmp = iph;
234 
235         err = crypto_ahash_digest(req);
236         if (err) {
237                 if (err == -EINPROGRESS)
238                         goto out;
239 
240                 if (err == -EBUSY)
241                         err = NET_XMIT_DROP;
242                 goto out_free;
243         }
244 
245         memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
246 
247         top_iph->tos = iph->tos;
248         top_iph->ttl = iph->ttl;
249         top_iph->frag_off = iph->frag_off;
250         if (top_iph->ihl != 5) {
251                 top_iph->daddr = iph->daddr;
252                 memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
253         }
254 
255 out_free:
256         kfree(iph);
257 out:
258         return err;
259 }
260 
261 static void ah_input_done(struct crypto_async_request *base, int err)
262 {
263         u8 *auth_data;
264         u8 *icv;
265         struct iphdr *work_iph;
266         struct sk_buff *skb = base->data;
267         struct xfrm_state *x = xfrm_input_state(skb);
268         struct ah_data *ahp = x->data;
269         struct ip_auth_hdr *ah = ip_auth_hdr(skb);
270         int ihl = ip_hdrlen(skb);
271         int ah_hlen = (ah->hdrlen + 2) << 2;
272 
273         work_iph = AH_SKB_CB(skb)->tmp;
274         auth_data = ah_tmp_auth(work_iph, ihl);
275         icv = ah_tmp_icv(ahp->ahash, auth_data, ahp->icv_trunc_len);
276 
277         err = memcmp(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG: 0;
278         if (err)
279                 goto out;
280 
281         err = ah->nexthdr;
282 
283         skb->network_header += ah_hlen;
284         memcpy(skb_network_header(skb), work_iph, ihl);
285         __skb_pull(skb, ah_hlen + ihl);
286 
287         if (x->props.mode == XFRM_MODE_TUNNEL)
288                 skb_reset_transport_header(skb);
289         else
290                 skb_set_transport_header(skb, -ihl);
291 out:
292         kfree(AH_SKB_CB(skb)->tmp);
293         xfrm_input_resume(skb, err);
294 }
295 
296 static int ah_input(struct xfrm_state *x, struct sk_buff *skb)
297 {
298         int ah_hlen;
299         int ihl;
300         int nexthdr;
301         int nfrags;
302         u8 *auth_data;
303         u8 *icv;
304         struct sk_buff *trailer;
305         struct crypto_ahash *ahash;
306         struct ahash_request *req;
307         struct scatterlist *sg;
308         struct iphdr *iph, *work_iph;
309         struct ip_auth_hdr *ah;
310         struct ah_data *ahp;
311         int err = -ENOMEM;
312         int seqhi_len = 0;
313         __be32 *seqhi;
314         int sglists = 0;
315         struct scatterlist *seqhisg;
316 
317         if (!pskb_may_pull(skb, sizeof(*ah)))
318                 goto out;
319 
320         ah = (struct ip_auth_hdr *)skb->data;
321         ahp = x->data;
322         ahash = ahp->ahash;
323 
324         nexthdr = ah->nexthdr;
325         ah_hlen = (ah->hdrlen + 2) << 2;
326 
327         if (x->props.flags & XFRM_STATE_ALIGN4) {
328                 if (ah_hlen != XFRM_ALIGN4(sizeof(*ah) + ahp->icv_full_len) &&
329                     ah_hlen != XFRM_ALIGN4(sizeof(*ah) + ahp->icv_trunc_len))
330                         goto out;
331         } else {
332                 if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) &&
333                     ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len))
334                         goto out;
335         }
336 
337         if (!pskb_may_pull(skb, ah_hlen))
338                 goto out;
339 
340         /* We are going to _remove_ AH header to keep sockets happy,
341          * so... Later this can change. */
342         if (skb_unclone(skb, GFP_ATOMIC))
343                 goto out;
344 
345         skb->ip_summed = CHECKSUM_NONE;
346 
347 
348         if ((err = skb_cow_data(skb, 0, &trailer)) < 0)
349                 goto out;
350         nfrags = err;
351 
352         ah = (struct ip_auth_hdr *)skb->data;
353         iph = ip_hdr(skb);
354         ihl = ip_hdrlen(skb);
355 
356         if (x->props.flags & XFRM_STATE_ESN) {
357                 sglists = 1;
358                 seqhi_len = sizeof(*seqhi);
359         }
360 
361         work_iph = ah_alloc_tmp(ahash, nfrags + sglists, ihl +
362                                 ahp->icv_trunc_len + seqhi_len);
363         if (!work_iph) {
364                 err = -ENOMEM;
365                 goto out;
366         }
367 
368         seqhi = (__be32 *)((char *)work_iph + ihl);
369         auth_data = ah_tmp_auth(seqhi, seqhi_len);
370         icv = ah_tmp_icv(ahash, auth_data, ahp->icv_trunc_len);
371         req = ah_tmp_req(ahash, icv);
372         sg = ah_req_sg(ahash, req);
373         seqhisg = sg + nfrags;
374 
375         memcpy(work_iph, iph, ihl);
376         memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
377         memset(ah->auth_data, 0, ahp->icv_trunc_len);
378 
379         iph->ttl = 0;
380         iph->tos = 0;
381         iph->frag_off = 0;
382         iph->check = 0;
383         if (ihl > sizeof(*iph)) {
384                 __be32 dummy;
385                 err = ip_clear_mutable_options(iph, &dummy);
386                 if (err)
387                         goto out_free;
388         }
389 
390         skb_push(skb, ihl);
391 
392         sg_init_table(sg, nfrags + sglists);
393         skb_to_sgvec_nomark(skb, sg, 0, skb->len);
394 
395         if (x->props.flags & XFRM_STATE_ESN) {
396                 /* Attach seqhi sg right after packet payload */
397                 *seqhi = XFRM_SKB_CB(skb)->seq.input.hi;
398                 sg_set_buf(seqhisg, seqhi, seqhi_len);
399         }
400         ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len);
401         ahash_request_set_callback(req, 0, ah_input_done, skb);
402 
403         AH_SKB_CB(skb)->tmp = work_iph;
404 
405         err = crypto_ahash_digest(req);
406         if (err) {
407                 if (err == -EINPROGRESS)
408                         goto out;
409 
410                 goto out_free;
411         }
412 
413         err = memcmp(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG: 0;
414         if (err)
415                 goto out_free;
416 
417         skb->network_header += ah_hlen;
418         memcpy(skb_network_header(skb), work_iph, ihl);
419         __skb_pull(skb, ah_hlen + ihl);
420         if (x->props.mode == XFRM_MODE_TUNNEL)
421                 skb_reset_transport_header(skb);
422         else
423                 skb_set_transport_header(skb, -ihl);
424 
425         err = nexthdr;
426 
427 out_free:
428         kfree (work_iph);
429 out:
430         return err;
431 }
432 
433 static int ah4_err(struct sk_buff *skb, u32 info)
434 {
435         struct net *net = dev_net(skb->dev);
436         const struct iphdr *iph = (const struct iphdr *)skb->data;
437         struct ip_auth_hdr *ah = (struct ip_auth_hdr *)(skb->data+(iph->ihl<<2));
438         struct xfrm_state *x;
439 
440         switch (icmp_hdr(skb)->type) {
441         case ICMP_DEST_UNREACH:
442                 if (icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
443                         return 0;
444         case ICMP_REDIRECT:
445                 break;
446         default:
447                 return 0;
448         }
449 
450         x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
451                               ah->spi, IPPROTO_AH, AF_INET);
452         if (!x)
453                 return 0;
454 
455         if (icmp_hdr(skb)->type == ICMP_DEST_UNREACH)
456                 ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_AH, 0);
457         else
458                 ipv4_redirect(skb, net, 0, 0, IPPROTO_AH, 0);
459         xfrm_state_put(x);
460 
461         return 0;
462 }
463 
464 static int ah_init_state(struct xfrm_state *x)
465 {
466         struct ah_data *ahp = NULL;
467         struct xfrm_algo_desc *aalg_desc;
468         struct crypto_ahash *ahash;
469 
470         if (!x->aalg)
471                 goto error;
472 
473         if (x->encap)
474                 goto error;
475 
476         ahp = kzalloc(sizeof(*ahp), GFP_KERNEL);
477         if (!ahp)
478                 return -ENOMEM;
479 
480         ahash = crypto_alloc_ahash(x->aalg->alg_name, 0, 0);
481         if (IS_ERR(ahash))
482                 goto error;
483 
484         ahp->ahash = ahash;
485         if (crypto_ahash_setkey(ahash, x->aalg->alg_key,
486                                 (x->aalg->alg_key_len + 7) / 8))
487                 goto error;
488 
489         /*
490          * Lookup the algorithm description maintained by xfrm_algo,
491          * verify crypto transform properties, and store information
492          * we need for AH processing.  This lookup cannot fail here
493          * after a successful crypto_alloc_ahash().
494          */
495         aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
496         BUG_ON(!aalg_desc);
497 
498         if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
499             crypto_ahash_digestsize(ahash)) {
500                 pr_info("%s: %s digestsize %u != %hu\n",
501                         __func__, x->aalg->alg_name,
502                         crypto_ahash_digestsize(ahash),
503                         aalg_desc->uinfo.auth.icv_fullbits / 8);
504                 goto error;
505         }
506 
507         ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
508         ahp->icv_trunc_len = x->aalg->alg_trunc_len/8;
509 
510         if (x->props.flags & XFRM_STATE_ALIGN4)
511                 x->props.header_len = XFRM_ALIGN4(sizeof(struct ip_auth_hdr) +
512                                                   ahp->icv_trunc_len);
513         else
514                 x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) +
515                                                   ahp->icv_trunc_len);
516         if (x->props.mode == XFRM_MODE_TUNNEL)
517                 x->props.header_len += sizeof(struct iphdr);
518         x->data = ahp;
519 
520         return 0;
521 
522 error:
523         if (ahp) {
524                 crypto_free_ahash(ahp->ahash);
525                 kfree(ahp);
526         }
527         return -EINVAL;
528 }
529 
530 static void ah_destroy(struct xfrm_state *x)
531 {
532         struct ah_data *ahp = x->data;
533 
534         if (!ahp)
535                 return;
536 
537         crypto_free_ahash(ahp->ahash);
538         kfree(ahp);
539 }
540 
541 static int ah4_rcv_cb(struct sk_buff *skb, int err)
542 {
543         return 0;
544 }
545 
546 static const struct xfrm_type ah_type =
547 {
548         .description    = "AH4",
549         .owner          = THIS_MODULE,
550         .proto          = IPPROTO_AH,
551         .flags          = XFRM_TYPE_REPLAY_PROT,
552         .init_state     = ah_init_state,
553         .destructor     = ah_destroy,
554         .input          = ah_input,
555         .output         = ah_output
556 };
557 
558 static struct xfrm4_protocol ah4_protocol = {
559         .handler        =       xfrm4_rcv,
560         .input_handler  =       xfrm_input,
561         .cb_handler     =       ah4_rcv_cb,
562         .err_handler    =       ah4_err,
563         .priority       =       0,
564 };
565 
566 static int __init ah4_init(void)
567 {
568         if (xfrm_register_type(&ah_type, AF_INET) < 0) {
569                 pr_info("%s: can't add xfrm type\n", __func__);
570                 return -EAGAIN;
571         }
572         if (xfrm4_protocol_register(&ah4_protocol, IPPROTO_AH) < 0) {
573                 pr_info("%s: can't add protocol\n", __func__);
574                 xfrm_unregister_type(&ah_type, AF_INET);
575                 return -EAGAIN;
576         }
577         return 0;
578 }
579 
580 static void __exit ah4_fini(void)
581 {
582         if (xfrm4_protocol_deregister(&ah4_protocol, IPPROTO_AH) < 0)
583                 pr_info("%s: can't remove protocol\n", __func__);
584         if (xfrm_unregister_type(&ah_type, AF_INET) < 0)
585                 pr_info("%s: can't remove xfrm type\n", __func__);
586 }
587 
588 module_init(ah4_init);
589 module_exit(ah4_fini);
590 MODULE_LICENSE("GPL");
591 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_AH);
592 

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