xref: /openbmc/linux/net/ipv4/esp4.c (revision fbb6b31a) 
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 crypto_aead *aead = x->data;
101 	int extralen = 0;
102 	u8 *iv;
103 	struct aead_request *req;
104 	struct scatterlist *sg;
105 
106 	if (x->props.flags & XFRM_STATE_ESN)
107 		extralen += sizeof(struct esp_output_extra);
108 
109 	iv = esp_tmp_iv(aead, tmp, extralen);
110 	req = esp_tmp_req(aead, iv);
111 
112 	/* Unref skb_frag_pages in the src scatterlist if necessary.
113 	 * Skip the first sg which comes from skb->data.
114 	 */
115 	if (req->src != req->dst)
116 		for (sg = sg_next(req->src); sg; sg = sg_next(sg))
117 			put_page(sg_page(sg));
118 }
119 
120 #ifdef CONFIG_INET_ESPINTCP
121 struct esp_tcp_sk {
122 	struct sock *sk;
123 	struct rcu_head rcu;
124 };
125 
126 static void esp_free_tcp_sk(struct rcu_head *head)
127 {
128 	struct esp_tcp_sk *esk = container_of(head, struct esp_tcp_sk, rcu);
129 
130 	sock_put(esk->sk);
131 	kfree(esk);
132 }
133 
134 static struct sock *esp_find_tcp_sk(struct xfrm_state *x)
135 {
136 	struct xfrm_encap_tmpl *encap = x->encap;
137 	struct esp_tcp_sk *esk;
138 	__be16 sport, dport;
139 	struct sock *nsk;
140 	struct sock *sk;
141 
142 	sk = rcu_dereference(x->encap_sk);
143 	if (sk && sk->sk_state == TCP_ESTABLISHED)
144 		return sk;
145 
146 	spin_lock_bh(&x->lock);
147 	sport = encap->encap_sport;
148 	dport = encap->encap_dport;
149 	nsk = rcu_dereference_protected(x->encap_sk,
150 					lockdep_is_held(&x->lock));
151 	if (sk && sk == nsk) {
152 		esk = kmalloc(sizeof(*esk), GFP_ATOMIC);
153 		if (!esk) {
154 			spin_unlock_bh(&x->lock);
155 			return ERR_PTR(-ENOMEM);
156 		}
157 		RCU_INIT_POINTER(x->encap_sk, NULL);
158 		esk->sk = sk;
159 		call_rcu(&esk->rcu, esp_free_tcp_sk);
160 	}
161 	spin_unlock_bh(&x->lock);
162 
163 	sk = inet_lookup_established(xs_net(x), &tcp_hashinfo, x->id.daddr.a4,
164 				     dport, x->props.saddr.a4, sport, 0);
165 	if (!sk)
166 		return ERR_PTR(-ENOENT);
167 
168 	if (!tcp_is_ulp_esp(sk)) {
169 		sock_put(sk);
170 		return ERR_PTR(-EINVAL);
171 	}
172 
173 	spin_lock_bh(&x->lock);
174 	nsk = rcu_dereference_protected(x->encap_sk,
175 					lockdep_is_held(&x->lock));
176 	if (encap->encap_sport != sport ||
177 	    encap->encap_dport != dport) {
178 		sock_put(sk);
179 		sk = nsk ?: ERR_PTR(-EREMCHG);
180 	} else if (sk == nsk) {
181 		sock_put(sk);
182 	} else {
183 		rcu_assign_pointer(x->encap_sk, sk);
184 	}
185 	spin_unlock_bh(&x->lock);
186 
187 	return sk;
188 }
189 
190 static int esp_output_tcp_finish(struct xfrm_state *x, struct sk_buff *skb)
191 {
192 	struct sock *sk;
193 	int err;
194 
195 	rcu_read_lock();
196 
197 	sk = esp_find_tcp_sk(x);
198 	err = PTR_ERR_OR_ZERO(sk);
199 	if (err)
200 		goto out;
201 
202 	bh_lock_sock(sk);
203 	if (sock_owned_by_user(sk))
204 		err = espintcp_queue_out(sk, skb);
205 	else
206 		err = espintcp_push_skb(sk, skb);
207 	bh_unlock_sock(sk);
208 
209 out:
210 	rcu_read_unlock();
211 	return err;
212 }
213 
214 static int esp_output_tcp_encap_cb(struct net *net, struct sock *sk,
215 				   struct sk_buff *skb)
216 {
217 	struct dst_entry *dst = skb_dst(skb);
218 	struct xfrm_state *x = dst->xfrm;
219 
220 	return esp_output_tcp_finish(x, skb);
221 }
222 
223 static int esp_output_tail_tcp(struct xfrm_state *x, struct sk_buff *skb)
224 {
225 	int err;
226 
227 	local_bh_disable();
228 	err = xfrm_trans_queue_net(xs_net(x), skb, esp_output_tcp_encap_cb);
229 	local_bh_enable();
230 
231 	/* EINPROGRESS just happens to do the right thing.  It
232 	 * actually means that the skb has been consumed and
233 	 * isn't coming back.
234 	 */
235 	return err ?: -EINPROGRESS;
236 }
237 #else
238 static int esp_output_tail_tcp(struct xfrm_state *x, struct sk_buff *skb)
239 {
240 	kfree_skb(skb);
241 
242 	return -EOPNOTSUPP;
243 }
244 #endif
245 
246 static void esp_output_done(struct crypto_async_request *base, int err)
247 {
248 	struct sk_buff *skb = base->data;
249 	struct xfrm_offload *xo = xfrm_offload(skb);
250 	void *tmp;
251 	struct xfrm_state *x;
252 
253 	if (xo && (xo->flags & XFRM_DEV_RESUME)) {
254 		struct sec_path *sp = skb_sec_path(skb);
255 
256 		x = sp->xvec[sp->len - 1];
257 	} else {
258 		x = skb_dst(skb)->xfrm;
259 	}
260 
261 	tmp = ESP_SKB_CB(skb)->tmp;
262 	esp_ssg_unref(x, tmp);
263 	kfree(tmp);
264 
265 	if (xo && (xo->flags & XFRM_DEV_RESUME)) {
266 		if (err) {
267 			XFRM_INC_STATS(xs_net(x), LINUX_MIB_XFRMOUTSTATEPROTOERROR);
268 			kfree_skb(skb);
269 			return;
270 		}
271 
272 		skb_push(skb, skb->data - skb_mac_header(skb));
273 		secpath_reset(skb);
274 		xfrm_dev_resume(skb);
275 	} else {
276 		if (!err &&
277 		    x->encap && x->encap->encap_type == TCP_ENCAP_ESPINTCP)
278 			esp_output_tail_tcp(x, skb);
279 		else
280 			xfrm_output_resume(skb->sk, skb, err);
281 	}
282 }
283 
284 /* Move ESP header back into place. */
285 static void esp_restore_header(struct sk_buff *skb, unsigned int offset)
286 {
287 	struct ip_esp_hdr *esph = (void *)(skb->data + offset);
288 	void *tmp = ESP_SKB_CB(skb)->tmp;
289 	__be32 *seqhi = esp_tmp_extra(tmp);
290 
291 	esph->seq_no = esph->spi;
292 	esph->spi = *seqhi;
293 }
294 
295 static void esp_output_restore_header(struct sk_buff *skb)
296 {
297 	void *tmp = ESP_SKB_CB(skb)->tmp;
298 	struct esp_output_extra *extra = esp_tmp_extra(tmp);
299 
300 	esp_restore_header(skb, skb_transport_offset(skb) + extra->esphoff -
301 				sizeof(__be32));
302 }
303 
304 static struct ip_esp_hdr *esp_output_set_extra(struct sk_buff *skb,
305 					       struct xfrm_state *x,
306 					       struct ip_esp_hdr *esph,
307 					       struct esp_output_extra *extra)
308 {
309 	/* For ESN we move the header forward by 4 bytes to
310 	 * accommodate the high bits.  We will move it back after
311 	 * encryption.
312 	 */
313 	if ((x->props.flags & XFRM_STATE_ESN)) {
314 		__u32 seqhi;
315 		struct xfrm_offload *xo = xfrm_offload(skb);
316 
317 		if (xo)
318 			seqhi = xo->seq.hi;
319 		else
320 			seqhi = XFRM_SKB_CB(skb)->seq.output.hi;
321 
322 		extra->esphoff = (unsigned char *)esph -
323 				 skb_transport_header(skb);
324 		esph = (struct ip_esp_hdr *)((unsigned char *)esph - 4);
325 		extra->seqhi = esph->spi;
326 		esph->seq_no = htonl(seqhi);
327 	}
328 
329 	esph->spi = x->id.spi;
330 
331 	return esph;
332 }
333 
334 static void esp_output_done_esn(struct crypto_async_request *base, int err)
335 {
336 	struct sk_buff *skb = base->data;
337 
338 	esp_output_restore_header(skb);
339 	esp_output_done(base, err);
340 }
341 
342 static struct ip_esp_hdr *esp_output_udp_encap(struct sk_buff *skb,
343 					       int encap_type,
344 					       struct esp_info *esp,
345 					       __be16 sport,
346 					       __be16 dport)
347 {
348 	struct udphdr *uh;
349 	__be32 *udpdata32;
350 	unsigned int len;
351 
352 	len = skb->len + esp->tailen - skb_transport_offset(skb);
353 	if (len + sizeof(struct iphdr) > IP_MAX_MTU)
354 		return ERR_PTR(-EMSGSIZE);
355 
356 	uh = (struct udphdr *)esp->esph;
357 	uh->source = sport;
358 	uh->dest = dport;
359 	uh->len = htons(len);
360 	uh->check = 0;
361 
362 	*skb_mac_header(skb) = IPPROTO_UDP;
363 
364 	if (encap_type == UDP_ENCAP_ESPINUDP_NON_IKE) {
365 		udpdata32 = (__be32 *)(uh + 1);
366 		udpdata32[0] = udpdata32[1] = 0;
367 		return (struct ip_esp_hdr *)(udpdata32 + 2);
368 	}
369 
370 	return (struct ip_esp_hdr *)(uh + 1);
371 }
372 
373 #ifdef CONFIG_INET_ESPINTCP
374 static struct ip_esp_hdr *esp_output_tcp_encap(struct xfrm_state *x,
375 						    struct sk_buff *skb,
376 						    struct esp_info *esp)
377 {
378 	__be16 *lenp = (void *)esp->esph;
379 	struct ip_esp_hdr *esph;
380 	unsigned int len;
381 	struct sock *sk;
382 
383 	len = skb->len + esp->tailen - skb_transport_offset(skb);
384 	if (len > IP_MAX_MTU)
385 		return ERR_PTR(-EMSGSIZE);
386 
387 	rcu_read_lock();
388 	sk = esp_find_tcp_sk(x);
389 	rcu_read_unlock();
390 
391 	if (IS_ERR(sk))
392 		return ERR_CAST(sk);
393 
394 	*lenp = htons(len);
395 	esph = (struct ip_esp_hdr *)(lenp + 1);
396 
397 	return esph;
398 }
399 #else
400 static struct ip_esp_hdr *esp_output_tcp_encap(struct xfrm_state *x,
401 						    struct sk_buff *skb,
402 						    struct esp_info *esp)
403 {
404 	return ERR_PTR(-EOPNOTSUPP);
405 }
406 #endif
407 
408 static int esp_output_encap(struct xfrm_state *x, struct sk_buff *skb,
409 			    struct esp_info *esp)
410 {
411 	struct xfrm_encap_tmpl *encap = x->encap;
412 	struct ip_esp_hdr *esph;
413 	__be16 sport, dport;
414 	int encap_type;
415 
416 	spin_lock_bh(&x->lock);
417 	sport = encap->encap_sport;
418 	dport = encap->encap_dport;
419 	encap_type = encap->encap_type;
420 	spin_unlock_bh(&x->lock);
421 
422 	switch (encap_type) {
423 	default:
424 	case UDP_ENCAP_ESPINUDP:
425 	case UDP_ENCAP_ESPINUDP_NON_IKE:
426 		esph = esp_output_udp_encap(skb, encap_type, esp, sport, dport);
427 		break;
428 	case TCP_ENCAP_ESPINTCP:
429 		esph = esp_output_tcp_encap(x, skb, esp);
430 		break;
431 	}
432 
433 	if (IS_ERR(esph))
434 		return PTR_ERR(esph);
435 
436 	esp->esph = esph;
437 
438 	return 0;
439 }
440 
441 int esp_output_head(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *esp)
442 {
443 	u8 *tail;
444 	int nfrags;
445 	int esph_offset;
446 	struct page *page;
447 	struct sk_buff *trailer;
448 	int tailen = esp->tailen;
449 
450 	/* this is non-NULL only with TCP/UDP Encapsulation */
451 	if (x->encap) {
452 		int err = esp_output_encap(x, skb, esp);
453 
454 		if (err < 0)
455 			return err;
456 	}
457 
458 	if (ALIGN(tailen, L1_CACHE_BYTES) > PAGE_SIZE ||
459 	    ALIGN(skb->data_len, L1_CACHE_BYTES) > PAGE_SIZE)
460 		goto cow;
461 
462 	if (!skb_cloned(skb)) {
463 		if (tailen <= skb_tailroom(skb)) {
464 			nfrags = 1;
465 			trailer = skb;
466 			tail = skb_tail_pointer(trailer);
467 
468 			goto skip_cow;
469 		} else if ((skb_shinfo(skb)->nr_frags < MAX_SKB_FRAGS)
470 			   && !skb_has_frag_list(skb)) {
471 			int allocsize;
472 			struct sock *sk = skb->sk;
473 			struct page_frag *pfrag = &x->xfrag;
474 
475 			esp->inplace = false;
476 
477 			allocsize = ALIGN(tailen, L1_CACHE_BYTES);
478 
479 			spin_lock_bh(&x->lock);
480 
481 			if (unlikely(!skb_page_frag_refill(allocsize, pfrag, GFP_ATOMIC))) {
482 				spin_unlock_bh(&x->lock);
483 				goto cow;
484 			}
485 
486 			page = pfrag->page;
487 			get_page(page);
488 
489 			tail = page_address(page) + pfrag->offset;
490 
491 			esp_output_fill_trailer(tail, esp->tfclen, esp->plen, esp->proto);
492 
493 			nfrags = skb_shinfo(skb)->nr_frags;
494 
495 			__skb_fill_page_desc(skb, nfrags, page, pfrag->offset,
496 					     tailen);
497 			skb_shinfo(skb)->nr_frags = ++nfrags;
498 
499 			pfrag->offset = pfrag->offset + allocsize;
500 
501 			spin_unlock_bh(&x->lock);
502 
503 			nfrags++;
504 
505 			skb->len += tailen;
506 			skb->data_len += tailen;
507 			skb->truesize += tailen;
508 			if (sk && sk_fullsock(sk))
509 				refcount_add(tailen, &sk->sk_wmem_alloc);
510 
511 			goto out;
512 		}
513 	}
514 
515 cow:
516 	esph_offset = (unsigned char *)esp->esph - skb_transport_header(skb);
517 
518 	nfrags = skb_cow_data(skb, tailen, &trailer);
519 	if (nfrags < 0)
520 		goto out;
521 	tail = skb_tail_pointer(trailer);
522 	esp->esph = (struct ip_esp_hdr *)(skb_transport_header(skb) + esph_offset);
523 
524 skip_cow:
525 	esp_output_fill_trailer(tail, esp->tfclen, esp->plen, esp->proto);
526 	pskb_put(skb, trailer, tailen);
527 
528 out:
529 	return nfrags;
530 }
531 EXPORT_SYMBOL_GPL(esp_output_head);
532 
533 int esp_output_tail(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *esp)
534 {
535 	u8 *iv;
536 	int alen;
537 	void *tmp;
538 	int ivlen;
539 	int assoclen;
540 	int extralen;
541 	struct page *page;
542 	struct ip_esp_hdr *esph;
543 	struct crypto_aead *aead;
544 	struct aead_request *req;
545 	struct scatterlist *sg, *dsg;
546 	struct esp_output_extra *extra;
547 	int err = -ENOMEM;
548 
549 	assoclen = sizeof(struct ip_esp_hdr);
550 	extralen = 0;
551 
552 	if (x->props.flags & XFRM_STATE_ESN) {
553 		extralen += sizeof(*extra);
554 		assoclen += sizeof(__be32);
555 	}
556 
557 	aead = x->data;
558 	alen = crypto_aead_authsize(aead);
559 	ivlen = crypto_aead_ivsize(aead);
560 
561 	tmp = esp_alloc_tmp(aead, esp->nfrags + 2, extralen);
562 	if (!tmp)
563 		goto error;
564 
565 	extra = esp_tmp_extra(tmp);
566 	iv = esp_tmp_iv(aead, tmp, extralen);
567 	req = esp_tmp_req(aead, iv);
568 	sg = esp_req_sg(aead, req);
569 
570 	if (esp->inplace)
571 		dsg = sg;
572 	else
573 		dsg = &sg[esp->nfrags];
574 
575 	esph = esp_output_set_extra(skb, x, esp->esph, extra);
576 	esp->esph = esph;
577 
578 	sg_init_table(sg, esp->nfrags);
579 	err = skb_to_sgvec(skb, sg,
580 		           (unsigned char *)esph - skb->data,
581 		           assoclen + ivlen + esp->clen + alen);
582 	if (unlikely(err < 0))
583 		goto error_free;
584 
585 	if (!esp->inplace) {
586 		int allocsize;
587 		struct page_frag *pfrag = &x->xfrag;
588 
589 		allocsize = ALIGN(skb->data_len, L1_CACHE_BYTES);
590 
591 		spin_lock_bh(&x->lock);
592 		if (unlikely(!skb_page_frag_refill(allocsize, pfrag, GFP_ATOMIC))) {
593 			spin_unlock_bh(&x->lock);
594 			goto error_free;
595 		}
596 
597 		skb_shinfo(skb)->nr_frags = 1;
598 
599 		page = pfrag->page;
600 		get_page(page);
601 		/* replace page frags in skb with new page */
602 		__skb_fill_page_desc(skb, 0, page, pfrag->offset, skb->data_len);
603 		pfrag->offset = pfrag->offset + allocsize;
604 		spin_unlock_bh(&x->lock);
605 
606 		sg_init_table(dsg, skb_shinfo(skb)->nr_frags + 1);
607 		err = skb_to_sgvec(skb, dsg,
608 			           (unsigned char *)esph - skb->data,
609 			           assoclen + ivlen + esp->clen + alen);
610 		if (unlikely(err < 0))
611 			goto error_free;
612 	}
613 
614 	if ((x->props.flags & XFRM_STATE_ESN))
615 		aead_request_set_callback(req, 0, esp_output_done_esn, skb);
616 	else
617 		aead_request_set_callback(req, 0, esp_output_done, skb);
618 
619 	aead_request_set_crypt(req, sg, dsg, ivlen + esp->clen, iv);
620 	aead_request_set_ad(req, assoclen);
621 
622 	memset(iv, 0, ivlen);
623 	memcpy(iv + ivlen - min(ivlen, 8), (u8 *)&esp->seqno + 8 - min(ivlen, 8),
624 	       min(ivlen, 8));
625 
626 	ESP_SKB_CB(skb)->tmp = tmp;
627 	err = crypto_aead_encrypt(req);
628 
629 	switch (err) {
630 	case -EINPROGRESS:
631 		goto error;
632 
633 	case -ENOSPC:
634 		err = NET_XMIT_DROP;
635 		break;
636 
637 	case 0:
638 		if ((x->props.flags & XFRM_STATE_ESN))
639 			esp_output_restore_header(skb);
640 	}
641 
642 	if (sg != dsg)
643 		esp_ssg_unref(x, tmp);
644 
645 	if (!err && x->encap && x->encap->encap_type == TCP_ENCAP_ESPINTCP)
646 		err = esp_output_tail_tcp(x, skb);
647 
648 error_free:
649 	kfree(tmp);
650 error:
651 	return err;
652 }
653 EXPORT_SYMBOL_GPL(esp_output_tail);
654 
655 static int esp_output(struct xfrm_state *x, struct sk_buff *skb)
656 {
657 	int alen;
658 	int blksize;
659 	struct ip_esp_hdr *esph;
660 	struct crypto_aead *aead;
661 	struct esp_info esp;
662 
663 	esp.inplace = true;
664 
665 	esp.proto = *skb_mac_header(skb);
666 	*skb_mac_header(skb) = IPPROTO_ESP;
667 
668 	/* skb is pure payload to encrypt */
669 
670 	aead = x->data;
671 	alen = crypto_aead_authsize(aead);
672 
673 	esp.tfclen = 0;
674 	if (x->tfcpad) {
675 		struct xfrm_dst *dst = (struct xfrm_dst *)skb_dst(skb);
676 		u32 padto;
677 
678 		padto = min(x->tfcpad, xfrm_state_mtu(x, dst->child_mtu_cached));
679 		if (skb->len < padto)
680 			esp.tfclen = padto - skb->len;
681 	}
682 	blksize = ALIGN(crypto_aead_blocksize(aead), 4);
683 	esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
684 	esp.plen = esp.clen - skb->len - esp.tfclen;
685 	esp.tailen = esp.tfclen + esp.plen + alen;
686 
687 	esp.esph = ip_esp_hdr(skb);
688 
689 	esp.nfrags = esp_output_head(x, skb, &esp);
690 	if (esp.nfrags < 0)
691 		return esp.nfrags;
692 
693 	esph = esp.esph;
694 	esph->spi = x->id.spi;
695 
696 	esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
697 	esp.seqno = cpu_to_be64(XFRM_SKB_CB(skb)->seq.output.low +
698 				 ((u64)XFRM_SKB_CB(skb)->seq.output.hi << 32));
699 
700 	skb_push(skb, -skb_network_offset(skb));
701 
702 	return esp_output_tail(x, skb, &esp);
703 }
704 
705 static inline int esp_remove_trailer(struct sk_buff *skb)
706 {
707 	struct xfrm_state *x = xfrm_input_state(skb);
708 	struct xfrm_offload *xo = xfrm_offload(skb);
709 	struct crypto_aead *aead = x->data;
710 	int alen, hlen, elen;
711 	int padlen, trimlen;
712 	__wsum csumdiff;
713 	u8 nexthdr[2];
714 	int ret;
715 
716 	alen = crypto_aead_authsize(aead);
717 	hlen = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead);
718 	elen = skb->len - hlen;
719 
720 	if (xo && (xo->flags & XFRM_ESP_NO_TRAILER)) {
721 		ret = xo->proto;
722 		goto out;
723 	}
724 
725 	if (skb_copy_bits(skb, skb->len - alen - 2, nexthdr, 2))
726 		BUG();
727 
728 	ret = -EINVAL;
729 	padlen = nexthdr[0];
730 	if (padlen + 2 + alen >= elen) {
731 		net_dbg_ratelimited("ipsec esp packet is garbage padlen=%d, elen=%d\n",
732 				    padlen + 2, elen - alen);
733 		goto out;
734 	}
735 
736 	trimlen = alen + padlen + 2;
737 	if (skb->ip_summed == CHECKSUM_COMPLETE) {
738 		csumdiff = skb_checksum(skb, skb->len - trimlen, trimlen, 0);
739 		skb->csum = csum_block_sub(skb->csum, csumdiff,
740 					   skb->len - trimlen);
741 	}
742 	pskb_trim(skb, skb->len - trimlen);
743 
744 	ret = nexthdr[1];
745 
746 out:
747 	return ret;
748 }
749 
750 int esp_input_done2(struct sk_buff *skb, int err)
751 {
752 	const struct iphdr *iph;
753 	struct xfrm_state *x = xfrm_input_state(skb);
754 	struct xfrm_offload *xo = xfrm_offload(skb);
755 	struct crypto_aead *aead = x->data;
756 	int hlen = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead);
757 	int ihl;
758 
759 	if (!xo || !(xo->flags & CRYPTO_DONE))
760 		kfree(ESP_SKB_CB(skb)->tmp);
761 
762 	if (unlikely(err))
763 		goto out;
764 
765 	err = esp_remove_trailer(skb);
766 	if (unlikely(err < 0))
767 		goto out;
768 
769 	iph = ip_hdr(skb);
770 	ihl = iph->ihl * 4;
771 
772 	if (x->encap) {
773 		struct xfrm_encap_tmpl *encap = x->encap;
774 		struct tcphdr *th = (void *)(skb_network_header(skb) + ihl);
775 		struct udphdr *uh = (void *)(skb_network_header(skb) + ihl);
776 		__be16 source;
777 
778 		switch (x->encap->encap_type) {
779 		case TCP_ENCAP_ESPINTCP:
780 			source = th->source;
781 			break;
782 		case UDP_ENCAP_ESPINUDP:
783 		case UDP_ENCAP_ESPINUDP_NON_IKE:
784 			source = uh->source;
785 			break;
786 		default:
787 			WARN_ON_ONCE(1);
788 			err = -EINVAL;
789 			goto out;
790 		}
791 
792 		/*
793 		 * 1) if the NAT-T peer's IP or port changed then
794 		 *    advertize the change to the keying daemon.
795 		 *    This is an inbound SA, so just compare
796 		 *    SRC ports.
797 		 */
798 		if (iph->saddr != x->props.saddr.a4 ||
799 		    source != encap->encap_sport) {
800 			xfrm_address_t ipaddr;
801 
802 			ipaddr.a4 = iph->saddr;
803 			km_new_mapping(x, &ipaddr, source);
804 
805 			/* XXX: perhaps add an extra
806 			 * policy check here, to see
807 			 * if we should allow or
808 			 * reject a packet from a
809 			 * different source
810 			 * address/port.
811 			 */
812 		}
813 
814 		/*
815 		 * 2) ignore UDP/TCP checksums in case
816 		 *    of NAT-T in Transport Mode, or
817 		 *    perform other post-processing fixes
818 		 *    as per draft-ietf-ipsec-udp-encaps-06,
819 		 *    section 3.1.2
820 		 */
821 		if (x->props.mode == XFRM_MODE_TRANSPORT)
822 			skb->ip_summed = CHECKSUM_UNNECESSARY;
823 	}
824 
825 	skb_pull_rcsum(skb, hlen);
826 	if (x->props.mode == XFRM_MODE_TUNNEL)
827 		skb_reset_transport_header(skb);
828 	else
829 		skb_set_transport_header(skb, -ihl);
830 
831 	/* RFC4303: Drop dummy packets without any error */
832 	if (err == IPPROTO_NONE)
833 		err = -EINVAL;
834 
835 out:
836 	return err;
837 }
838 EXPORT_SYMBOL_GPL(esp_input_done2);
839 
840 static void esp_input_done(struct crypto_async_request *base, int err)
841 {
842 	struct sk_buff *skb = base->data;
843 
844 	xfrm_input_resume(skb, esp_input_done2(skb, err));
845 }
846 
847 static void esp_input_restore_header(struct sk_buff *skb)
848 {
849 	esp_restore_header(skb, 0);
850 	__skb_pull(skb, 4);
851 }
852 
853 static void esp_input_set_header(struct sk_buff *skb, __be32 *seqhi)
854 {
855 	struct xfrm_state *x = xfrm_input_state(skb);
856 	struct ip_esp_hdr *esph;
857 
858 	/* For ESN we move the header forward by 4 bytes to
859 	 * accommodate the high bits.  We will move it back after
860 	 * decryption.
861 	 */
862 	if ((x->props.flags & XFRM_STATE_ESN)) {
863 		esph = skb_push(skb, 4);
864 		*seqhi = esph->spi;
865 		esph->spi = esph->seq_no;
866 		esph->seq_no = XFRM_SKB_CB(skb)->seq.input.hi;
867 	}
868 }
869 
870 static void esp_input_done_esn(struct crypto_async_request *base, int err)
871 {
872 	struct sk_buff *skb = base->data;
873 
874 	esp_input_restore_header(skb);
875 	esp_input_done(base, err);
876 }
877 
878 /*
879  * Note: detecting truncated vs. non-truncated authentication data is very
880  * expensive, so we only support truncated data, which is the recommended
881  * and common case.
882  */
883 static int esp_input(struct xfrm_state *x, struct sk_buff *skb)
884 {
885 	struct crypto_aead *aead = x->data;
886 	struct aead_request *req;
887 	struct sk_buff *trailer;
888 	int ivlen = crypto_aead_ivsize(aead);
889 	int elen = skb->len - sizeof(struct ip_esp_hdr) - ivlen;
890 	int nfrags;
891 	int assoclen;
892 	int seqhilen;
893 	__be32 *seqhi;
894 	void *tmp;
895 	u8 *iv;
896 	struct scatterlist *sg;
897 	int err = -EINVAL;
898 
899 	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + ivlen))
900 		goto out;
901 
902 	if (elen <= 0)
903 		goto out;
904 
905 	assoclen = sizeof(struct ip_esp_hdr);
906 	seqhilen = 0;
907 
908 	if (x->props.flags & XFRM_STATE_ESN) {
909 		seqhilen += sizeof(__be32);
910 		assoclen += seqhilen;
911 	}
912 
913 	if (!skb_cloned(skb)) {
914 		if (!skb_is_nonlinear(skb)) {
915 			nfrags = 1;
916 
917 			goto skip_cow;
918 		} else if (!skb_has_frag_list(skb)) {
919 			nfrags = skb_shinfo(skb)->nr_frags;
920 			nfrags++;
921 
922 			goto skip_cow;
923 		}
924 	}
925 
926 	err = skb_cow_data(skb, 0, &trailer);
927 	if (err < 0)
928 		goto out;
929 
930 	nfrags = err;
931 
932 skip_cow:
933 	err = -ENOMEM;
934 	tmp = esp_alloc_tmp(aead, nfrags, seqhilen);
935 	if (!tmp)
936 		goto out;
937 
938 	ESP_SKB_CB(skb)->tmp = tmp;
939 	seqhi = esp_tmp_extra(tmp);
940 	iv = esp_tmp_iv(aead, tmp, seqhilen);
941 	req = esp_tmp_req(aead, iv);
942 	sg = esp_req_sg(aead, req);
943 
944 	esp_input_set_header(skb, seqhi);
945 
946 	sg_init_table(sg, nfrags);
947 	err = skb_to_sgvec(skb, sg, 0, skb->len);
948 	if (unlikely(err < 0)) {
949 		kfree(tmp);
950 		goto out;
951 	}
952 
953 	skb->ip_summed = CHECKSUM_NONE;
954 
955 	if ((x->props.flags & XFRM_STATE_ESN))
956 		aead_request_set_callback(req, 0, esp_input_done_esn, skb);
957 	else
958 		aead_request_set_callback(req, 0, esp_input_done, skb);
959 
960 	aead_request_set_crypt(req, sg, sg, elen + ivlen, iv);
961 	aead_request_set_ad(req, assoclen);
962 
963 	err = crypto_aead_decrypt(req);
964 	if (err == -EINPROGRESS)
965 		goto out;
966 
967 	if ((x->props.flags & XFRM_STATE_ESN))
968 		esp_input_restore_header(skb);
969 
970 	err = esp_input_done2(skb, err);
971 
972 out:
973 	return err;
974 }
975 
976 static int esp4_err(struct sk_buff *skb, u32 info)
977 {
978 	struct net *net = dev_net(skb->dev);
979 	const struct iphdr *iph = (const struct iphdr *)skb->data;
980 	struct ip_esp_hdr *esph = (struct ip_esp_hdr *)(skb->data+(iph->ihl<<2));
981 	struct xfrm_state *x;
982 
983 	switch (icmp_hdr(skb)->type) {
984 	case ICMP_DEST_UNREACH:
985 		if (icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
986 			return 0;
987 		break;
988 	case ICMP_REDIRECT:
989 		break;
990 	default:
991 		return 0;
992 	}
993 
994 	x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
995 			      esph->spi, IPPROTO_ESP, AF_INET);
996 	if (!x)
997 		return 0;
998 
999 	if (icmp_hdr(skb)->type == ICMP_DEST_UNREACH)
1000 		ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ESP);
1001 	else
1002 		ipv4_redirect(skb, net, 0, IPPROTO_ESP);
1003 	xfrm_state_put(x);
1004 
1005 	return 0;
1006 }
1007 
1008 static void esp_destroy(struct xfrm_state *x)
1009 {
1010 	struct crypto_aead *aead = x->data;
1011 
1012 	if (!aead)
1013 		return;
1014 
1015 	crypto_free_aead(aead);
1016 }
1017 
1018 static int esp_init_aead(struct xfrm_state *x)
1019 {
1020 	char aead_name[CRYPTO_MAX_ALG_NAME];
1021 	struct crypto_aead *aead;
1022 	int err;
1023 
1024 	err = -ENAMETOOLONG;
1025 	if (snprintf(aead_name, CRYPTO_MAX_ALG_NAME, "%s(%s)",
1026 		     x->geniv, x->aead->alg_name) >= CRYPTO_MAX_ALG_NAME)
1027 		goto error;
1028 
1029 	aead = crypto_alloc_aead(aead_name, 0, 0);
1030 	err = PTR_ERR(aead);
1031 	if (IS_ERR(aead))
1032 		goto error;
1033 
1034 	x->data = aead;
1035 
1036 	err = crypto_aead_setkey(aead, x->aead->alg_key,
1037 				 (x->aead->alg_key_len + 7) / 8);
1038 	if (err)
1039 		goto error;
1040 
1041 	err = crypto_aead_setauthsize(aead, x->aead->alg_icv_len / 8);
1042 	if (err)
1043 		goto error;
1044 
1045 error:
1046 	return err;
1047 }
1048 
1049 static int esp_init_authenc(struct xfrm_state *x)
1050 {
1051 	struct crypto_aead *aead;
1052 	struct crypto_authenc_key_param *param;
1053 	struct rtattr *rta;
1054 	char *key;
1055 	char *p;
1056 	char authenc_name[CRYPTO_MAX_ALG_NAME];
1057 	unsigned int keylen;
1058 	int err;
1059 
1060 	err = -EINVAL;
1061 	if (!x->ealg)
1062 		goto error;
1063 
1064 	err = -ENAMETOOLONG;
1065 
1066 	if ((x->props.flags & XFRM_STATE_ESN)) {
1067 		if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME,
1068 			     "%s%sauthencesn(%s,%s)%s",
1069 			     x->geniv ?: "", x->geniv ? "(" : "",
1070 			     x->aalg ? x->aalg->alg_name : "digest_null",
1071 			     x->ealg->alg_name,
1072 			     x->geniv ? ")" : "") >= CRYPTO_MAX_ALG_NAME)
1073 			goto error;
1074 	} else {
1075 		if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME,
1076 			     "%s%sauthenc(%s,%s)%s",
1077 			     x->geniv ?: "", x->geniv ? "(" : "",
1078 			     x->aalg ? x->aalg->alg_name : "digest_null",
1079 			     x->ealg->alg_name,
1080 			     x->geniv ? ")" : "") >= CRYPTO_MAX_ALG_NAME)
1081 			goto error;
1082 	}
1083 
1084 	aead = crypto_alloc_aead(authenc_name, 0, 0);
1085 	err = PTR_ERR(aead);
1086 	if (IS_ERR(aead))
1087 		goto error;
1088 
1089 	x->data = aead;
1090 
1091 	keylen = (x->aalg ? (x->aalg->alg_key_len + 7) / 8 : 0) +
1092 		 (x->ealg->alg_key_len + 7) / 8 + RTA_SPACE(sizeof(*param));
1093 	err = -ENOMEM;
1094 	key = kmalloc(keylen, GFP_KERNEL);
1095 	if (!key)
1096 		goto error;
1097 
1098 	p = key;
1099 	rta = (void *)p;
1100 	rta->rta_type = CRYPTO_AUTHENC_KEYA_PARAM;
1101 	rta->rta_len = RTA_LENGTH(sizeof(*param));
1102 	param = RTA_DATA(rta);
1103 	p += RTA_SPACE(sizeof(*param));
1104 
1105 	if (x->aalg) {
1106 		struct xfrm_algo_desc *aalg_desc;
1107 
1108 		memcpy(p, x->aalg->alg_key, (x->aalg->alg_key_len + 7) / 8);
1109 		p += (x->aalg->alg_key_len + 7) / 8;
1110 
1111 		aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
1112 		BUG_ON(!aalg_desc);
1113 
1114 		err = -EINVAL;
1115 		if (aalg_desc->uinfo.auth.icv_fullbits / 8 !=
1116 		    crypto_aead_authsize(aead)) {
1117 			pr_info("ESP: %s digestsize %u != %hu\n",
1118 				x->aalg->alg_name,
1119 				crypto_aead_authsize(aead),
1120 				aalg_desc->uinfo.auth.icv_fullbits / 8);
1121 			goto free_key;
1122 		}
1123 
1124 		err = crypto_aead_setauthsize(
1125 			aead, x->aalg->alg_trunc_len / 8);
1126 		if (err)
1127 			goto free_key;
1128 	}
1129 
1130 	param->enckeylen = cpu_to_be32((x->ealg->alg_key_len + 7) / 8);
1131 	memcpy(p, x->ealg->alg_key, (x->ealg->alg_key_len + 7) / 8);
1132 
1133 	err = crypto_aead_setkey(aead, key, keylen);
1134 
1135 free_key:
1136 	kfree(key);
1137 
1138 error:
1139 	return err;
1140 }
1141 
1142 static int esp_init_state(struct xfrm_state *x)
1143 {
1144 	struct crypto_aead *aead;
1145 	u32 align;
1146 	int err;
1147 
1148 	x->data = NULL;
1149 
1150 	if (x->aead)
1151 		err = esp_init_aead(x);
1152 	else
1153 		err = esp_init_authenc(x);
1154 
1155 	if (err)
1156 		goto error;
1157 
1158 	aead = x->data;
1159 
1160 	x->props.header_len = sizeof(struct ip_esp_hdr) +
1161 			      crypto_aead_ivsize(aead);
1162 	if (x->props.mode == XFRM_MODE_TUNNEL)
1163 		x->props.header_len += sizeof(struct iphdr);
1164 	else if (x->props.mode == XFRM_MODE_BEET && x->sel.family != AF_INET6)
1165 		x->props.header_len += IPV4_BEET_PHMAXLEN;
1166 	if (x->encap) {
1167 		struct xfrm_encap_tmpl *encap = x->encap;
1168 
1169 		switch (encap->encap_type) {
1170 		default:
1171 			err = -EINVAL;
1172 			goto error;
1173 		case UDP_ENCAP_ESPINUDP:
1174 			x->props.header_len += sizeof(struct udphdr);
1175 			break;
1176 		case UDP_ENCAP_ESPINUDP_NON_IKE:
1177 			x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32);
1178 			break;
1179 #ifdef CONFIG_INET_ESPINTCP
1180 		case TCP_ENCAP_ESPINTCP:
1181 			/* only the length field, TCP encap is done by
1182 			 * the socket
1183 			 */
1184 			x->props.header_len += 2;
1185 			break;
1186 #endif
1187 		}
1188 	}
1189 
1190 	align = ALIGN(crypto_aead_blocksize(aead), 4);
1191 	x->props.trailer_len = align + 1 + crypto_aead_authsize(aead);
1192 
1193 error:
1194 	return err;
1195 }
1196 
1197 static int esp4_rcv_cb(struct sk_buff *skb, int err)
1198 {
1199 	return 0;
1200 }
1201 
1202 static const struct xfrm_type esp_type =
1203 {
1204 	.owner		= THIS_MODULE,
1205 	.proto	     	= IPPROTO_ESP,
1206 	.flags		= XFRM_TYPE_REPLAY_PROT,
1207 	.init_state	= esp_init_state,
1208 	.destructor	= esp_destroy,
1209 	.input		= esp_input,
1210 	.output		= esp_output,
1211 };
1212 
1213 static struct xfrm4_protocol esp4_protocol = {
1214 	.handler	=	xfrm4_rcv,
1215 	.input_handler	=	xfrm_input,
1216 	.cb_handler	=	esp4_rcv_cb,
1217 	.err_handler	=	esp4_err,
1218 	.priority	=	0,
1219 };
1220 
1221 static int __init esp4_init(void)
1222 {
1223 	if (xfrm_register_type(&esp_type, AF_INET) < 0) {
1224 		pr_info("%s: can't add xfrm type\n", __func__);
1225 		return -EAGAIN;
1226 	}
1227 	if (xfrm4_protocol_register(&esp4_protocol, IPPROTO_ESP) < 0) {
1228 		pr_info("%s: can't add protocol\n", __func__);
1229 		xfrm_unregister_type(&esp_type, AF_INET);
1230 		return -EAGAIN;
1231 	}
1232 	return 0;
1233 }
1234 
1235 static void __exit esp4_fini(void)
1236 {
1237 	if (xfrm4_protocol_deregister(&esp4_protocol, IPPROTO_ESP) < 0)
1238 		pr_info("%s: can't remove protocol\n", __func__);
1239 	xfrm_unregister_type(&esp_type, AF_INET);
1240 }
1241 
1242 module_init(esp4_init);
1243 module_exit(esp4_fini);
1244 MODULE_LICENSE("GPL");
1245 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_ESP);
1246