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TOMOYO Linux Cross Reference
Linux/net/ipv4/esp4.c

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  1 // SPDX-License-Identifier: GPL-2.0-only
  2 #define pr_fmt(fmt) "IPsec: " fmt
  3 
  4 #include <crypto/aead.h>
  5 #include <crypto/authenc.h>
  6 #include <linux/err.h>
  7 #include <linux/module.h>
  8 #include <net/ip.h>
  9 #include <net/xfrm.h>
 10 #include <net/esp.h>
 11 #include <linux/scatterlist.h>
 12 #include <linux/kernel.h>
 13 #include <linux/pfkeyv2.h>
 14 #include <linux/rtnetlink.h>
 15 #include <linux/slab.h>
 16 #include <linux/spinlock.h>
 17 #include <linux/in6.h>
 18 #include <net/icmp.h>
 19 #include <net/protocol.h>
 20 #include <net/udp.h>
 21 #include <net/tcp.h>
 22 #include <net/espintcp.h>
 23 
 24 #include <linux/highmem.h>
 25 
 26 struct esp_skb_cb {
 27         struct xfrm_skb_cb xfrm;
 28         void *tmp;
 29 };
 30 
 31 struct esp_output_extra {
 32         __be32 seqhi;
 33         u32 esphoff;
 34 };
 35 
 36 #define ESP_SKB_CB(__skb) ((struct esp_skb_cb *)&((__skb)->cb[0]))
 37 
 38 /*
 39  * Allocate an AEAD request structure with extra space for SG and IV.
 40  *
 41  * For alignment considerations the IV is placed at the front, followed
 42  * by the request and finally the SG list.
 43  *
 44  * TODO: Use spare space in skb for this where possible.
 45  */
 46 static void *esp_alloc_tmp(struct crypto_aead *aead, int nfrags, int extralen)
 47 {
 48         unsigned int len;
 49 
 50         len = extralen;
 51 
 52         len += crypto_aead_ivsize(aead);
 53 
 54         if (len) {
 55                 len += crypto_aead_alignmask(aead) &
 56                        ~(crypto_tfm_ctx_alignment() - 1);
 57                 len = ALIGN(len, crypto_tfm_ctx_alignment());
 58         }
 59 
 60         len += sizeof(struct aead_request) + crypto_aead_reqsize(aead);
 61         len = ALIGN(len, __alignof__(struct scatterlist));
 62 
 63         len += sizeof(struct scatterlist) * nfrags;
 64 
 65         return kmalloc(len, GFP_ATOMIC);
 66 }
 67 
 68 static inline void *esp_tmp_extra(void *tmp)
 69 {
 70         return PTR_ALIGN(tmp, __alignof__(struct esp_output_extra));
 71 }
 72 
 73 static inline u8 *esp_tmp_iv(struct crypto_aead *aead, void *tmp, int extralen)
 74 {
 75         return crypto_aead_ivsize(aead) ?
 76                PTR_ALIGN((u8 *)tmp + extralen,
 77                          crypto_aead_alignmask(aead) + 1) : tmp + extralen;
 78 }
 79 
 80 static inline struct aead_request *esp_tmp_req(struct crypto_aead *aead, u8 *iv)
 81 {
 82         struct aead_request *req;
 83 
 84         req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead),
 85                                 crypto_tfm_ctx_alignment());
 86         aead_request_set_tfm(req, aead);
 87         return req;
 88 }
 89 
 90 static inline struct scatterlist *esp_req_sg(struct crypto_aead *aead,
 91                                              struct aead_request *req)
 92 {
 93         return (void *)ALIGN((unsigned long)(req + 1) +
 94                              crypto_aead_reqsize(aead),
 95                              __alignof__(struct scatterlist));
 96 }
 97 
 98 static void esp_ssg_unref(struct xfrm_state *x, void *tmp)
 99 {
100         struct esp_output_extra *extra = esp_tmp_extra(tmp);
101         struct crypto_aead *aead = x->data;
102         int extralen = 0;
103         u8 *iv;
104         struct aead_request *req;
105         struct scatterlist *sg;
106 
107         if (x->props.flags & XFRM_STATE_ESN)
108                 extralen += sizeof(*extra);
109 
110         extra = esp_tmp_extra(tmp);
111         iv = esp_tmp_iv(aead, tmp, extralen);
112         req = esp_tmp_req(aead, iv);
113 
114         /* Unref skb_frag_pages in the src scatterlist if necessary.
115          * Skip the first sg which comes from skb->data.
116          */
117         if (req->src != req->dst)
118                 for (sg = sg_next(req->src); sg; sg = sg_next(sg))
119                         put_page(sg_page(sg));
120 }
121 
122 #ifdef CONFIG_INET_ESPINTCP
123 struct esp_tcp_sk {
124         struct sock *sk;
125         struct rcu_head rcu;
126 };
127 
128 static void esp_free_tcp_sk(struct rcu_head *head)
129 {
130         struct esp_tcp_sk *esk = container_of(head, struct esp_tcp_sk, rcu);
131 
132         sock_put(esk->sk);
133         kfree(esk);
134 }
135 
136 static struct sock *esp_find_tcp_sk(struct xfrm_state *x)
137 {
138         struct xfrm_encap_tmpl *encap = x->encap;
139         struct esp_tcp_sk *esk;
140         __be16 sport, dport;
141         struct sock *nsk;
142         struct sock *sk;
143 
144         sk = rcu_dereference(x->encap_sk);
145         if (sk && sk->sk_state == TCP_ESTABLISHED)
146                 return sk;
147 
148         spin_lock_bh(&x->lock);
149         sport = encap->encap_sport;
150         dport = encap->encap_dport;
151         nsk = rcu_dereference_protected(x->encap_sk,
152                                         lockdep_is_held(&x->lock));
153         if (sk && sk == nsk) {
154                 esk = kmalloc(sizeof(*esk), GFP_ATOMIC);
155                 if (!esk) {
156                         spin_unlock_bh(&x->lock);
157                         return ERR_PTR(-ENOMEM);
158                 }
159                 RCU_INIT_POINTER(x->encap_sk, NULL);
160                 esk->sk = sk;
161                 call_rcu(&esk->rcu, esp_free_tcp_sk);
162         }
163         spin_unlock_bh(&x->lock);
164 
165         sk = inet_lookup_established(xs_net(x), &tcp_hashinfo, x->id.daddr.a4,
166                                      dport, x->props.saddr.a4, sport, 0);
167         if (!sk)
168                 return ERR_PTR(-ENOENT);
169 
170         if (!tcp_is_ulp_esp(sk)) {
171                 sock_put(sk);
172                 return ERR_PTR(-EINVAL);
173         }
174 
175         spin_lock_bh(&x->lock);
176         nsk = rcu_dereference_protected(x->encap_sk,
177                                         lockdep_is_held(&x->lock));
178         if (encap->encap_sport != sport ||
179             encap->encap_dport != dport) {
180                 sock_put(sk);
181                 sk = nsk ?: ERR_PTR(-EREMCHG);
182         } else if (sk == nsk) {
183                 sock_put(sk);
184         } else {
185                 rcu_assign_pointer(x->encap_sk, sk);
186         }
187         spin_unlock_bh(&x->lock);
188 
189         return sk;
190 }
191 
192 static int esp_output_tcp_finish(struct xfrm_state *x, struct sk_buff *skb)
193 {
194         struct sock *sk;
195         int err;
196 
197         rcu_read_lock();
198 
199         sk = esp_find_tcp_sk(x);
200         err = PTR_ERR_OR_ZERO(sk);
201         if (err)
202                 goto out;
203 
204         bh_lock_sock(sk);
205         if (sock_owned_by_user(sk))
206                 err = espintcp_queue_out(sk, skb);
207         else
208                 err = espintcp_push_skb(sk, skb);
209         bh_unlock_sock(sk);
210 
211 out:
212         rcu_read_unlock();
213         return err;
214 }
215 
216 static int esp_output_tcp_encap_cb(struct net *net, struct sock *sk,
217                                    struct sk_buff *skb)
218 {
219         struct dst_entry *dst = skb_dst(skb);
220         struct xfrm_state *x = dst->xfrm;
221 
222         return esp_output_tcp_finish(x, skb);
223 }
224 
225 static int esp_output_tail_tcp(struct xfrm_state *x, struct sk_buff *skb)
226 {
227         int err;
228 
229         local_bh_disable();
230         err = xfrm_trans_queue_net(xs_net(x), skb, esp_output_tcp_encap_cb);
231         local_bh_enable();
232 
233         /* EINPROGRESS just happens to do the right thing.  It
234          * actually means that the skb has been consumed and
235          * isn't coming back.
236          */
237         return err ?: -EINPROGRESS;
238 }
239 #else
240 static int esp_output_tail_tcp(struct xfrm_state *x, struct sk_buff *skb)
241 {
242         kfree_skb(skb);
243 
244         return -EOPNOTSUPP;
245 }
246 #endif
247 
248 static void esp_output_done(struct crypto_async_request *base, int err)
249 {
250         struct sk_buff *skb = base->data;
251         struct xfrm_offload *xo = xfrm_offload(skb);
252         void *tmp;
253         struct xfrm_state *x;
254 
255         if (xo && (xo->flags & XFRM_DEV_RESUME)) {
256                 struct sec_path *sp = skb_sec_path(skb);
257 
258                 x = sp->xvec[sp->len - 1];
259         } else {
260                 x = skb_dst(skb)->xfrm;
261         }
262 
263         tmp = ESP_SKB_CB(skb)->tmp;
264         esp_ssg_unref(x, tmp);
265         kfree(tmp);
266 
267         if (xo && (xo->flags & XFRM_DEV_RESUME)) {
268                 if (err) {
269                         XFRM_INC_STATS(xs_net(x), LINUX_MIB_XFRMOUTSTATEPROTOERROR);
270                         kfree_skb(skb);
271                         return;
272                 }
273 
274                 skb_push(skb, skb->data - skb_mac_header(skb));
275                 secpath_reset(skb);
276                 xfrm_dev_resume(skb);
277         } else {
278                 if (!err &&
279                     x->encap && x->encap->encap_type == TCP_ENCAP_ESPINTCP)
280                         esp_output_tail_tcp(x, skb);
281                 else
282                         xfrm_output_resume(skb, err);
283         }
284 }
285 
286 /* Move ESP header back into place. */
287 static void esp_restore_header(struct sk_buff *skb, unsigned int offset)
288 {
289         struct ip_esp_hdr *esph = (void *)(skb->data + offset);
290         void *tmp = ESP_SKB_CB(skb)->tmp;
291         __be32 *seqhi = esp_tmp_extra(tmp);
292 
293         esph->seq_no = esph->spi;
294         esph->spi = *seqhi;
295 }
296 
297 static void esp_output_restore_header(struct sk_buff *skb)
298 {
299         void *tmp = ESP_SKB_CB(skb)->tmp;
300         struct esp_output_extra *extra = esp_tmp_extra(tmp);
301 
302         esp_restore_header(skb, skb_transport_offset(skb) + extra->esphoff -
303                                 sizeof(__be32));
304 }
305 
306 static struct ip_esp_hdr *esp_output_set_extra(struct sk_buff *skb,
307                                                struct xfrm_state *x,
308                                                struct ip_esp_hdr *esph,
309                                                struct esp_output_extra *extra)
310 {
311         /* For ESN we move the header forward by 4 bytes to
312          * accomodate the high bits.  We will move it back after
313          * encryption.
314          */
315         if ((x->props.flags & XFRM_STATE_ESN)) {
316                 __u32 seqhi;
317                 struct xfrm_offload *xo = xfrm_offload(skb);
318 
319                 if (xo)
320                         seqhi = xo->seq.hi;
321                 else
322                         seqhi = XFRM_SKB_CB(skb)->seq.output.hi;
323 
324                 extra->esphoff = (unsigned char *)esph -
325                                  skb_transport_header(skb);
326                 esph = (struct ip_esp_hdr *)((unsigned char *)esph - 4);
327                 extra->seqhi = esph->spi;
328                 esph->seq_no = htonl(seqhi);
329         }
330 
331         esph->spi = x->id.spi;
332 
333         return esph;
334 }
335 
336 static void esp_output_done_esn(struct crypto_async_request *base, int err)
337 {
338         struct sk_buff *skb = base->data;
339 
340         esp_output_restore_header(skb);
341         esp_output_done(base, err);
342 }
343 
344 static struct ip_esp_hdr *esp_output_udp_encap(struct sk_buff *skb,
345                                                int encap_type,
346                                                struct esp_info *esp,
347                                                __be16 sport,
348                                                __be16 dport)
349 {
350         struct udphdr *uh;
351         __be32 *udpdata32;
352         unsigned int len;
353 
354         len = skb->len + esp->tailen - skb_transport_offset(skb);
355         if (len + sizeof(struct iphdr) > IP_MAX_MTU)
356                 return ERR_PTR(-EMSGSIZE);
357 
358         uh = (struct udphdr *)esp->esph;
359         uh->source = sport;
360         uh->dest = dport;
361         uh->len = htons(len);
362         uh->check = 0;
363 
364         *skb_mac_header(skb) = IPPROTO_UDP;
365 
366         if (encap_type == UDP_ENCAP_ESPINUDP_NON_IKE) {
367                 udpdata32 = (__be32 *)(uh + 1);
368                 udpdata32[0] = udpdata32[1] = 0;
369                 return (struct ip_esp_hdr *)(udpdata32 + 2);
370         }
371 
372         return (struct ip_esp_hdr *)(uh + 1);
373 }
374 
375 #ifdef CONFIG_INET_ESPINTCP
376 static struct ip_esp_hdr *esp_output_tcp_encap(struct xfrm_state *x,
377                                                     struct sk_buff *skb,
378                                                     struct esp_info *esp)
379 {
380         __be16 *lenp = (void *)esp->esph;
381         struct ip_esp_hdr *esph;
382         unsigned int len;
383         struct sock *sk;
384 
385         len = skb->len + esp->tailen - skb_transport_offset(skb);
386         if (len > IP_MAX_MTU)
387                 return ERR_PTR(-EMSGSIZE);
388 
389         rcu_read_lock();
390         sk = esp_find_tcp_sk(x);
391         rcu_read_unlock();
392 
393         if (IS_ERR(sk))
394                 return ERR_CAST(sk);
395 
396         *lenp = htons(len);
397         esph = (struct ip_esp_hdr *)(lenp + 1);
398 
399         return esph;
400 }
401 #else
402 static struct ip_esp_hdr *esp_output_tcp_encap(struct xfrm_state *x,
403                                                     struct sk_buff *skb,
404                                                     struct esp_info *esp)
405 {
406         return ERR_PTR(-EOPNOTSUPP);
407 }
408 #endif
409 
410 static int esp_output_encap(struct xfrm_state *x, struct sk_buff *skb,
411                             struct esp_info *esp)
412 {
413         struct xfrm_encap_tmpl *encap = x->encap;
414         struct ip_esp_hdr *esph;
415         __be16 sport, dport;
416         int encap_type;
417 
418         spin_lock_bh(&x->lock);
419         sport = encap->encap_sport;
420         dport = encap->encap_dport;
421         encap_type = encap->encap_type;
422         spin_unlock_bh(&x->lock);
423 
424         switch (encap_type) {
425         default:
426         case UDP_ENCAP_ESPINUDP:
427         case UDP_ENCAP_ESPINUDP_NON_IKE:
428                 esph = esp_output_udp_encap(skb, encap_type, esp, sport, dport);
429                 break;
430         case TCP_ENCAP_ESPINTCP:
431                 esph = esp_output_tcp_encap(x, skb, esp);
432                 break;
433         }
434 
435         if (IS_ERR(esph))
436                 return PTR_ERR(esph);
437 
438         esp->esph = esph;
439 
440         return 0;
441 }
442 
443 int esp_output_head(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *esp)
444 {
445         u8 *tail;
446         u8 *vaddr;
447         int nfrags;
448         int esph_offset;
449         struct page *page;
450         struct sk_buff *trailer;
451         int tailen = esp->tailen;
452 
453         /* this is non-NULL only with TCP/UDP Encapsulation */
454         if (x->encap) {
455                 int err = esp_output_encap(x, skb, esp);
456 
457                 if (err < 0)
458                         return err;
459         }
460 
461         if (!skb_cloned(skb)) {
462                 if (tailen <= skb_tailroom(skb)) {
463                         nfrags = 1;
464                         trailer = skb;
465                         tail = skb_tail_pointer(trailer);
466 
467                         goto skip_cow;
468                 } else if ((skb_shinfo(skb)->nr_frags < MAX_SKB_FRAGS)
469                            && !skb_has_frag_list(skb)) {
470                         int allocsize;
471                         struct sock *sk = skb->sk;
472                         struct page_frag *pfrag = &x->xfrag;
473 
474                         esp->inplace = false;
475 
476                         allocsize = ALIGN(tailen, L1_CACHE_BYTES);
477 
478                         spin_lock_bh(&x->lock);
479 
480                         if (unlikely(!skb_page_frag_refill(allocsize, pfrag, GFP_ATOMIC))) {
481                                 spin_unlock_bh(&x->lock);
482                                 goto cow;
483                         }
484 
485                         page = pfrag->page;
486                         get_page(page);
487 
488                         vaddr = kmap_atomic(page);
489 
490                         tail = vaddr + pfrag->offset;
491 
492                         esp_output_fill_trailer(tail, esp->tfclen, esp->plen, esp->proto);
493 
494                         kunmap_atomic(vaddr);
495 
496                         nfrags = skb_shinfo(skb)->nr_frags;
497 
498                         __skb_fill_page_desc(skb, nfrags, page, pfrag->offset,
499                                              tailen);
500                         skb_shinfo(skb)->nr_frags = ++nfrags;
501 
502                         pfrag->offset = pfrag->offset + allocsize;
503 
504                         spin_unlock_bh(&x->lock);
505 
506                         nfrags++;
507 
508                         skb->len += tailen;
509                         skb->data_len += tailen;
510                         skb->truesize += tailen;
511                         if (sk && sk_fullsock(sk))
512                                 refcount_add(tailen, &sk->sk_wmem_alloc);
513 
514                         goto out;
515                 }
516         }
517 
518 cow:
519         esph_offset = (unsigned char *)esp->esph - skb_transport_header(skb);
520 
521         nfrags = skb_cow_data(skb, tailen, &trailer);
522         if (nfrags < 0)
523                 goto out;
524         tail = skb_tail_pointer(trailer);
525         esp->esph = (struct ip_esp_hdr *)(skb_transport_header(skb) + esph_offset);
526 
527 skip_cow:
528         esp_output_fill_trailer(tail, esp->tfclen, esp->plen, esp->proto);
529         pskb_put(skb, trailer, tailen);
530 
531 out:
532         return nfrags;
533 }
534 EXPORT_SYMBOL_GPL(esp_output_head);
535 
536 int esp_output_tail(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *esp)
537 {
538         u8 *iv;
539         int alen;
540         void *tmp;
541         int ivlen;
542         int assoclen;
543         int extralen;
544         struct page *page;
545         struct ip_esp_hdr *esph;
546         struct crypto_aead *aead;
547         struct aead_request *req;
548         struct scatterlist *sg, *dsg;
549         struct esp_output_extra *extra;
550         int err = -ENOMEM;
551 
552         assoclen = sizeof(struct ip_esp_hdr);
553         extralen = 0;
554 
555         if (x->props.flags & XFRM_STATE_ESN) {
556                 extralen += sizeof(*extra);
557                 assoclen += sizeof(__be32);
558         }
559 
560         aead = x->data;
561         alen = crypto_aead_authsize(aead);
562         ivlen = crypto_aead_ivsize(aead);
563 
564         tmp = esp_alloc_tmp(aead, esp->nfrags + 2, extralen);
565         if (!tmp)
566                 goto error;
567 
568         extra = esp_tmp_extra(tmp);
569         iv = esp_tmp_iv(aead, tmp, extralen);
570         req = esp_tmp_req(aead, iv);
571         sg = esp_req_sg(aead, req);
572 
573         if (esp->inplace)
574                 dsg = sg;
575         else
576                 dsg = &sg[esp->nfrags];
577 
578         esph = esp_output_set_extra(skb, x, esp->esph, extra);
579         esp->esph = esph;
580 
581         sg_init_table(sg, esp->nfrags);
582         err = skb_to_sgvec(skb, sg,
583                            (unsigned char *)esph - skb->data,
584                            assoclen + ivlen + esp->clen + alen);
585         if (unlikely(err < 0))
586                 goto error_free;
587 
588         if (!esp->inplace) {
589                 int allocsize;
590                 struct page_frag *pfrag = &x->xfrag;
591 
592                 allocsize = ALIGN(skb->data_len, L1_CACHE_BYTES);
593 
594                 spin_lock_bh(&x->lock);
595                 if (unlikely(!skb_page_frag_refill(allocsize, pfrag, GFP_ATOMIC))) {
596                         spin_unlock_bh(&x->lock);
597                         goto error_free;
598                 }
599 
600                 skb_shinfo(skb)->nr_frags = 1;
601 
602                 page = pfrag->page;
603                 get_page(page);
604                 /* replace page frags in skb with new page */
605                 __skb_fill_page_desc(skb, 0, page, pfrag->offset, skb->data_len);
606                 pfrag->offset = pfrag->offset + allocsize;
607                 spin_unlock_bh(&x->lock);
608 
609                 sg_init_table(dsg, skb_shinfo(skb)->nr_frags + 1);
610                 err = skb_to_sgvec(skb, dsg,
611                                    (unsigned char *)esph - skb->data,
612                                    assoclen + ivlen + esp->clen + alen);
613                 if (unlikely(err < 0))
614                         goto error_free;
615         }
616 
617         if ((x->props.flags & XFRM_STATE_ESN))
618                 aead_request_set_callback(req, 0, esp_output_done_esn, skb);
619         else
620                 aead_request_set_callback(req, 0, esp_output_done, skb);
621 
622         aead_request_set_crypt(req, sg, dsg, ivlen + esp->clen, iv);
623         aead_request_set_ad(req, assoclen);
624 
625         memset(iv, 0, ivlen);
626         memcpy(iv + ivlen - min(ivlen, 8), (u8 *)&esp->seqno + 8 - min(ivlen, 8),
627                min(ivlen, 8));
628 
629         ESP_SKB_CB(skb)->tmp = tmp;
630         err = crypto_aead_encrypt(req);
631 
632         switch (err) {
633         case -EINPROGRESS:
634                 goto error;
635 
636         case -ENOSPC:
637                 err = NET_XMIT_DROP;
638                 break;
639 
640         case 0:
641                 if ((x->props.flags & XFRM_STATE_ESN))
642                         esp_output_restore_header(skb);
643         }
644 
645         if (sg != dsg)
646                 esp_ssg_unref(x, tmp);
647 
648         if (!err && x->encap && x->encap->encap_type == TCP_ENCAP_ESPINTCP)
649                 err = esp_output_tail_tcp(x, skb);
650 
651 error_free:
652         kfree(tmp);
653 error:
654         return err;
655 }
656 EXPORT_SYMBOL_GPL(esp_output_tail);
657 
658 static int esp_output(struct xfrm_state *x, struct sk_buff *skb)
659 {
660         int alen;
661         int blksize;
662         struct ip_esp_hdr *esph;
663         struct crypto_aead *aead;
664         struct esp_info esp;
665 
666         esp.inplace = true;
667 
668         esp.proto = *skb_mac_header(skb);
669         *skb_mac_header(skb) = IPPROTO_ESP;
670 
671         /* skb is pure payload to encrypt */
672 
673         aead = x->data;
674         alen = crypto_aead_authsize(aead);
675 
676         esp.tfclen = 0;
677         if (x->tfcpad) {
678                 struct xfrm_dst *dst = (struct xfrm_dst *)skb_dst(skb);
679                 u32 padto;
680 
681                 padto = min(x->tfcpad, xfrm_state_mtu(x, dst->child_mtu_cached));
682                 if (skb->len < padto)
683                         esp.tfclen = padto - skb->len;
684         }
685         blksize = ALIGN(crypto_aead_blocksize(aead), 4);
686         esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
687         esp.plen = esp.clen - skb->len - esp.tfclen;
688         esp.tailen = esp.tfclen + esp.plen + alen;
689 
690         esp.esph = ip_esp_hdr(skb);
691 
692         esp.nfrags = esp_output_head(x, skb, &esp);
693         if (esp.nfrags < 0)
694                 return esp.nfrags;
695 
696         esph = esp.esph;
697         esph->spi = x->id.spi;
698 
699         esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
700         esp.seqno = cpu_to_be64(XFRM_SKB_CB(skb)->seq.output.low +
701                                  ((u64)XFRM_SKB_CB(skb)->seq.output.hi << 32));
702 
703         skb_push(skb, -skb_network_offset(skb));
704 
705         return esp_output_tail(x, skb, &esp);
706 }
707 
708 static inline int esp_remove_trailer(struct sk_buff *skb)
709 {
710         struct xfrm_state *x = xfrm_input_state(skb);
711         struct xfrm_offload *xo = xfrm_offload(skb);
712         struct crypto_aead *aead = x->data;
713         int alen, hlen, elen;
714         int padlen, trimlen;
715         __wsum csumdiff;
716         u8 nexthdr[2];
717         int ret;
718 
719         alen = crypto_aead_authsize(aead);
720         hlen = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead);
721         elen = skb->len - hlen;
722 
723         if (xo && (xo->flags & XFRM_ESP_NO_TRAILER)) {
724                 ret = xo->proto;
725                 goto out;
726         }
727 
728         if (skb_copy_bits(skb, skb->len - alen - 2, nexthdr, 2))
729                 BUG();
730 
731         ret = -EINVAL;
732         padlen = nexthdr[0];
733         if (padlen + 2 + alen >= elen) {
734                 net_dbg_ratelimited("ipsec esp packet is garbage padlen=%d, elen=%d\n",
735                                     padlen + 2, elen - alen);
736                 goto out;
737         }
738 
739         trimlen = alen + padlen + 2;
740         if (skb->ip_summed == CHECKSUM_COMPLETE) {
741                 csumdiff = skb_checksum(skb, skb->len - trimlen, trimlen, 0);
742                 skb->csum = csum_block_sub(skb->csum, csumdiff,
743                                            skb->len - trimlen);
744         }
745         pskb_trim(skb, skb->len - trimlen);
746 
747         ret = nexthdr[1];
748 
749 out:
750         return ret;
751 }
752 
753 int esp_input_done2(struct sk_buff *skb, int err)
754 {
755         const struct iphdr *iph;
756         struct xfrm_state *x = xfrm_input_state(skb);
757         struct xfrm_offload *xo = xfrm_offload(skb);
758         struct crypto_aead *aead = x->data;
759         int hlen = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead);
760         int ihl;
761 
762         if (!xo || (xo && !(xo->flags & CRYPTO_DONE)))
763                 kfree(ESP_SKB_CB(skb)->tmp);
764 
765         if (unlikely(err))
766                 goto out;
767 
768         err = esp_remove_trailer(skb);
769         if (unlikely(err < 0))
770                 goto out;
771 
772         iph = ip_hdr(skb);
773         ihl = iph->ihl * 4;
774 
775         if (x->encap) {
776                 struct xfrm_encap_tmpl *encap = x->encap;
777                 struct tcphdr *th = (void *)(skb_network_header(skb) + ihl);
778                 struct udphdr *uh = (void *)(skb_network_header(skb) + ihl);
779                 __be16 source;
780 
781                 switch (x->encap->encap_type) {
782                 case TCP_ENCAP_ESPINTCP:
783                         source = th->source;
784                         break;
785                 case UDP_ENCAP_ESPINUDP:
786                 case UDP_ENCAP_ESPINUDP_NON_IKE:
787                         source = uh->source;
788                         break;
789                 default:
790                         WARN_ON_ONCE(1);
791                         err = -EINVAL;
792                         goto out;
793                 }
794 
795                 /*
796                  * 1) if the NAT-T peer's IP or port changed then
797                  *    advertize the change to the keying daemon.
798                  *    This is an inbound SA, so just compare
799                  *    SRC ports.
800                  */
801                 if (iph->saddr != x->props.saddr.a4 ||
802                     source != encap->encap_sport) {
803                         xfrm_address_t ipaddr;
804 
805                         ipaddr.a4 = iph->saddr;
806                         km_new_mapping(x, &ipaddr, source);
807 
808                         /* XXX: perhaps add an extra
809                          * policy check here, to see
810                          * if we should allow or
811                          * reject a packet from a
812                          * different source
813                          * address/port.
814                          */
815                 }
816 
817                 /*
818                  * 2) ignore UDP/TCP checksums in case
819                  *    of NAT-T in Transport Mode, or
820                  *    perform other post-processing fixes
821                  *    as per draft-ietf-ipsec-udp-encaps-06,
822                  *    section 3.1.2
823                  */
824                 if (x->props.mode == XFRM_MODE_TRANSPORT)
825                         skb->ip_summed = CHECKSUM_UNNECESSARY;
826         }
827 
828         skb_pull_rcsum(skb, hlen);
829         if (x->props.mode == XFRM_MODE_TUNNEL)
830                 skb_reset_transport_header(skb);
831         else
832                 skb_set_transport_header(skb, -ihl);
833 
834         /* RFC4303: Drop dummy packets without any error */
835         if (err == IPPROTO_NONE)
836                 err = -EINVAL;
837 
838 out:
839         return err;
840 }
841 EXPORT_SYMBOL_GPL(esp_input_done2);
842 
843 static void esp_input_done(struct crypto_async_request *base, int err)
844 {
845         struct sk_buff *skb = base->data;
846 
847         xfrm_input_resume(skb, esp_input_done2(skb, err));
848 }
849 
850 static void esp_input_restore_header(struct sk_buff *skb)
851 {
852         esp_restore_header(skb, 0);
853         __skb_pull(skb, 4);
854 }
855 
856 static void esp_input_set_header(struct sk_buff *skb, __be32 *seqhi)
857 {
858         struct xfrm_state *x = xfrm_input_state(skb);
859         struct ip_esp_hdr *esph;
860 
861         /* For ESN we move the header forward by 4 bytes to
862          * accomodate the high bits.  We will move it back after
863          * decryption.
864          */
865         if ((x->props.flags & XFRM_STATE_ESN)) {
866                 esph = skb_push(skb, 4);
867                 *seqhi = esph->spi;
868                 esph->spi = esph->seq_no;
869                 esph->seq_no = XFRM_SKB_CB(skb)->seq.input.hi;
870         }
871 }
872 
873 static void esp_input_done_esn(struct crypto_async_request *base, int err)
874 {
875         struct sk_buff *skb = base->data;
876 
877         esp_input_restore_header(skb);
878         esp_input_done(base, err);
879 }
880 
881 /*
882  * Note: detecting truncated vs. non-truncated authentication data is very
883  * expensive, so we only support truncated data, which is the recommended
884  * and common case.
885  */
886 static int esp_input(struct xfrm_state *x, struct sk_buff *skb)
887 {
888         struct crypto_aead *aead = x->data;
889         struct aead_request *req;
890         struct sk_buff *trailer;
891         int ivlen = crypto_aead_ivsize(aead);
892         int elen = skb->len - sizeof(struct ip_esp_hdr) - ivlen;
893         int nfrags;
894         int assoclen;
895         int seqhilen;
896         __be32 *seqhi;
897         void *tmp;
898         u8 *iv;
899         struct scatterlist *sg;
900         int err = -EINVAL;
901 
902         if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + ivlen))
903                 goto out;
904 
905         if (elen <= 0)
906                 goto out;
907 
908         assoclen = sizeof(struct ip_esp_hdr);
909         seqhilen = 0;
910 
911         if (x->props.flags & XFRM_STATE_ESN) {
912                 seqhilen += sizeof(__be32);
913                 assoclen += seqhilen;
914         }
915 
916         if (!skb_cloned(skb)) {
917                 if (!skb_is_nonlinear(skb)) {
918                         nfrags = 1;
919 
920                         goto skip_cow;
921                 } else if (!skb_has_frag_list(skb)) {
922                         nfrags = skb_shinfo(skb)->nr_frags;
923                         nfrags++;
924 
925                         goto skip_cow;
926                 }
927         }
928 
929         err = skb_cow_data(skb, 0, &trailer);
930         if (err < 0)
931                 goto out;
932 
933         nfrags = err;
934 
935 skip_cow:
936         err = -ENOMEM;
937         tmp = esp_alloc_tmp(aead, nfrags, seqhilen);
938         if (!tmp)
939                 goto out;
940 
941         ESP_SKB_CB(skb)->tmp = tmp;
942         seqhi = esp_tmp_extra(tmp);
943         iv = esp_tmp_iv(aead, tmp, seqhilen);
944         req = esp_tmp_req(aead, iv);
945         sg = esp_req_sg(aead, req);
946 
947         esp_input_set_header(skb, seqhi);
948 
949         sg_init_table(sg, nfrags);
950         err = skb_to_sgvec(skb, sg, 0, skb->len);
951         if (unlikely(err < 0)) {
952                 kfree(tmp);
953                 goto out;
954         }
955 
956         skb->ip_summed = CHECKSUM_NONE;
957 
958         if ((x->props.flags & XFRM_STATE_ESN))
959                 aead_request_set_callback(req, 0, esp_input_done_esn, skb);
960         else
961                 aead_request_set_callback(req, 0, esp_input_done, skb);
962 
963         aead_request_set_crypt(req, sg, sg, elen + ivlen, iv);
964         aead_request_set_ad(req, assoclen);
965 
966         err = crypto_aead_decrypt(req);
967         if (err == -EINPROGRESS)
968                 goto out;
969 
970         if ((x->props.flags & XFRM_STATE_ESN))
971                 esp_input_restore_header(skb);
972 
973         err = esp_input_done2(skb, err);
974 
975 out:
976         return err;
977 }
978 
979 static int esp4_err(struct sk_buff *skb, u32 info)
980 {
981         struct net *net = dev_net(skb->dev);
982         const struct iphdr *iph = (const struct iphdr *)skb->data;
983         struct ip_esp_hdr *esph = (struct ip_esp_hdr *)(skb->data+(iph->ihl<<2));
984         struct xfrm_state *x;
985 
986         switch (icmp_hdr(skb)->type) {
987         case ICMP_DEST_UNREACH:
988                 if (icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
989                         return 0;
990         case ICMP_REDIRECT:
991                 break;
992         default:
993                 return 0;
994         }
995 
996         x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
997                               esph->spi, IPPROTO_ESP, AF_INET);
998         if (!x)
999                 return 0;
1000 
1001         if (icmp_hdr(skb)->type == ICMP_DEST_UNREACH)
1002                 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ESP);
1003         else
1004                 ipv4_redirect(skb, net, 0, IPPROTO_ESP);
1005         xfrm_state_put(x);
1006 
1007         return 0;
1008 }
1009 
1010 static void esp_destroy(struct xfrm_state *x)
1011 {
1012         struct crypto_aead *aead = x->data;
1013 
1014         if (!aead)
1015                 return;
1016 
1017         crypto_free_aead(aead);
1018 }
1019 
1020 static int esp_init_aead(struct xfrm_state *x)
1021 {
1022         char aead_name[CRYPTO_MAX_ALG_NAME];
1023         struct crypto_aead *aead;
1024         int err;
1025 
1026         err = -ENAMETOOLONG;
1027         if (snprintf(aead_name, CRYPTO_MAX_ALG_NAME, "%s(%s)",
1028                      x->geniv, x->aead->alg_name) >= CRYPTO_MAX_ALG_NAME)
1029                 goto error;
1030 
1031         aead = crypto_alloc_aead(aead_name, 0, 0);
1032         err = PTR_ERR(aead);
1033         if (IS_ERR(aead))
1034                 goto error;
1035 
1036         x->data = aead;
1037 
1038         err = crypto_aead_setkey(aead, x->aead->alg_key,
1039                                  (x->aead->alg_key_len + 7) / 8);
1040         if (err)
1041                 goto error;
1042 
1043         err = crypto_aead_setauthsize(aead, x->aead->alg_icv_len / 8);
1044         if (err)
1045                 goto error;
1046 
1047 error:
1048         return err;
1049 }
1050 
1051 static int esp_init_authenc(struct xfrm_state *x)
1052 {
1053         struct crypto_aead *aead;
1054         struct crypto_authenc_key_param *param;
1055         struct rtattr *rta;
1056         char *key;
1057         char *p;
1058         char authenc_name[CRYPTO_MAX_ALG_NAME];
1059         unsigned int keylen;
1060         int err;
1061 
1062         err = -EINVAL;
1063         if (!x->ealg)
1064                 goto error;
1065 
1066         err = -ENAMETOOLONG;
1067 
1068         if ((x->props.flags & XFRM_STATE_ESN)) {
1069                 if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME,
1070                              "%s%sauthencesn(%s,%s)%s",
1071                              x->geniv ?: "", x->geniv ? "(" : "",
1072                              x->aalg ? x->aalg->alg_name : "digest_null",
1073                              x->ealg->alg_name,
1074                              x->geniv ? ")" : "") >= CRYPTO_MAX_ALG_NAME)
1075                         goto error;
1076         } else {
1077                 if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME,
1078                              "%s%sauthenc(%s,%s)%s",
1079                              x->geniv ?: "", x->geniv ? "(" : "",
1080                              x->aalg ? x->aalg->alg_name : "digest_null",
1081                              x->ealg->alg_name,
1082                              x->geniv ? ")" : "") >= CRYPTO_MAX_ALG_NAME)
1083                         goto error;
1084         }
1085 
1086         aead = crypto_alloc_aead(authenc_name, 0, 0);
1087         err = PTR_ERR(aead);
1088         if (IS_ERR(aead))
1089                 goto error;
1090 
1091         x->data = aead;
1092 
1093         keylen = (x->aalg ? (x->aalg->alg_key_len + 7) / 8 : 0) +
1094                  (x->ealg->alg_key_len + 7) / 8 + RTA_SPACE(sizeof(*param));
1095         err = -ENOMEM;
1096         key = kmalloc(keylen, GFP_KERNEL);
1097         if (!key)
1098                 goto error;
1099 
1100         p = key;
1101         rta = (void *)p;
1102         rta->rta_type = CRYPTO_AUTHENC_KEYA_PARAM;
1103         rta->rta_len = RTA_LENGTH(sizeof(*param));
1104         param = RTA_DATA(rta);
1105         p += RTA_SPACE(sizeof(*param));
1106 
1107         if (x->aalg) {
1108                 struct xfrm_algo_desc *aalg_desc;
1109 
1110                 memcpy(p, x->aalg->alg_key, (x->aalg->alg_key_len + 7) / 8);
1111                 p += (x->aalg->alg_key_len + 7) / 8;
1112 
1113                 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
1114                 BUG_ON(!aalg_desc);
1115 
1116                 err = -EINVAL;
1117                 if (aalg_desc->uinfo.auth.icv_fullbits / 8 !=
1118                     crypto_aead_authsize(aead)) {
1119                         pr_info("ESP: %s digestsize %u != %hu\n",
1120                                 x->aalg->alg_name,
1121                                 crypto_aead_authsize(aead),
1122                                 aalg_desc->uinfo.auth.icv_fullbits / 8);
1123                         goto free_key;
1124                 }
1125 
1126                 err = crypto_aead_setauthsize(
1127                         aead, x->aalg->alg_trunc_len / 8);
1128                 if (err)
1129                         goto free_key;
1130         }
1131 
1132         param->enckeylen = cpu_to_be32((x->ealg->alg_key_len + 7) / 8);
1133         memcpy(p, x->ealg->alg_key, (x->ealg->alg_key_len + 7) / 8);
1134 
1135         err = crypto_aead_setkey(aead, key, keylen);
1136 
1137 free_key:
1138         kfree(key);
1139 
1140 error:
1141         return err;
1142 }
1143 
1144 static int esp_init_state(struct xfrm_state *x)
1145 {
1146         struct crypto_aead *aead;
1147         u32 align;
1148         int err;
1149 
1150         x->data = NULL;
1151 
1152         if (x->aead)
1153                 err = esp_init_aead(x);
1154         else
1155                 err = esp_init_authenc(x);
1156 
1157         if (err)
1158                 goto error;
1159 
1160         aead = x->data;
1161 
1162         x->props.header_len = sizeof(struct ip_esp_hdr) +
1163                               crypto_aead_ivsize(aead);
1164         if (x->props.mode == XFRM_MODE_TUNNEL)
1165                 x->props.header_len += sizeof(struct iphdr);
1166         else if (x->props.mode == XFRM_MODE_BEET && x->sel.family != AF_INET6)
1167                 x->props.header_len += IPV4_BEET_PHMAXLEN;
1168         if (x->encap) {
1169                 struct xfrm_encap_tmpl *encap = x->encap;
1170 
1171                 switch (encap->encap_type) {
1172                 default:
1173                         err = -EINVAL;
1174                         goto error;
1175                 case UDP_ENCAP_ESPINUDP:
1176                         x->props.header_len += sizeof(struct udphdr);
1177                         break;
1178                 case UDP_ENCAP_ESPINUDP_NON_IKE:
1179                         x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32);
1180                         break;
1181 #ifdef CONFIG_INET_ESPINTCP
1182                 case TCP_ENCAP_ESPINTCP:
1183                         /* only the length field, TCP encap is done by
1184                          * the socket
1185                          */
1186                         x->props.header_len += 2;
1187                         break;
1188 #endif
1189                 }
1190         }
1191 
1192         align = ALIGN(crypto_aead_blocksize(aead), 4);
1193         x->props.trailer_len = align + 1 + crypto_aead_authsize(aead);
1194 
1195 error:
1196         return err;
1197 }
1198 
1199 static int esp4_rcv_cb(struct sk_buff *skb, int err)
1200 {
1201         return 0;
1202 }
1203 
1204 static const struct xfrm_type esp_type =
1205 {
1206         .description    = "ESP4",
1207         .owner          = THIS_MODULE,
1208         .proto          = IPPROTO_ESP,
1209         .flags          = XFRM_TYPE_REPLAY_PROT,
1210         .init_state     = esp_init_state,
1211         .destructor     = esp_destroy,
1212         .input          = esp_input,
1213         .output         = esp_output,
1214 };
1215 
1216 static struct xfrm4_protocol esp4_protocol = {
1217         .handler        =       xfrm4_rcv,
1218         .input_handler  =       xfrm_input,
1219         .cb_handler     =       esp4_rcv_cb,
1220         .err_handler    =       esp4_err,
1221         .priority       =       0,
1222 };
1223 
1224 static int __init esp4_init(void)
1225 {
1226         if (xfrm_register_type(&esp_type, AF_INET) < 0) {
1227                 pr_info("%s: can't add xfrm type\n", __func__);
1228                 return -EAGAIN;
1229         }
1230         if (xfrm4_protocol_register(&esp4_protocol, IPPROTO_ESP) < 0) {
1231                 pr_info("%s: can't add protocol\n", __func__);
1232                 xfrm_unregister_type(&esp_type, AF_INET);
1233                 return -EAGAIN;
1234         }
1235         return 0;
1236 }
1237 
1238 static void __exit esp4_fini(void)
1239 {
1240         if (xfrm4_protocol_deregister(&esp4_protocol, IPPROTO_ESP) < 0)
1241                 pr_info("%s: can't remove protocol\n", __func__);
1242         xfrm_unregister_type(&esp_type, AF_INET);
1243 }
1244 
1245 module_init(esp4_init);
1246 module_exit(esp4_fini);
1247 MODULE_LICENSE("GPL");
1248 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_ESP);
1249 

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