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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  */
esp_alloc_tmp(struct crypto_aead * aead,int nfrags,int extralen)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 
esp_tmp_extra(void * tmp)68 static inline void *esp_tmp_extra(void *tmp)
69 {
70 	return PTR_ALIGN(tmp, __alignof__(struct esp_output_extra));
71 }
72 
esp_tmp_iv(struct crypto_aead * aead,void * tmp,int extralen)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 
esp_tmp_req(struct crypto_aead * aead,u8 * iv)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 
esp_req_sg(struct crypto_aead * aead,struct aead_request * req)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 
esp_ssg_unref(struct xfrm_state * x,void * tmp)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 
esp_free_tcp_sk(struct rcu_head * head)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 
esp_find_tcp_sk(struct xfrm_state * x)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 
esp_output_tcp_finish(struct xfrm_state * x,struct sk_buff * skb)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 
esp_output_tcp_encap_cb(struct net * net,struct sock * sk,struct sk_buff * skb)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 
esp_output_tail_tcp(struct xfrm_state * x,struct sk_buff * skb)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
esp_output_tail_tcp(struct xfrm_state * x,struct sk_buff * skb)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 
esp_output_done(struct crypto_async_request * base,int err)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. */
esp_restore_header(struct sk_buff * skb,unsigned int offset)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 
esp_output_restore_header(struct sk_buff * skb)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 
esp_output_set_extra(struct sk_buff * skb,struct xfrm_state * x,struct ip_esp_hdr * esph,struct esp_output_extra * extra)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 
esp_output_done_esn(struct crypto_async_request * base,int err)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 
esp_output_udp_encap(struct sk_buff * skb,int encap_type,struct esp_info * esp,__be16 sport,__be16 dport)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
esp_output_tcp_encap(struct xfrm_state * x,struct sk_buff * skb,struct esp_info * esp)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
esp_output_tcp_encap(struct xfrm_state * x,struct sk_buff * skb,struct esp_info * esp)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 
esp_output_encap(struct xfrm_state * x,struct sk_buff * skb,struct esp_info * esp)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 
esp_output_head(struct xfrm_state * x,struct sk_buff * skb,struct esp_info * esp)443 int esp_output_head(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *esp)
444 {
445 	u8 *tail;
446 	int nfrags;
447 	int esph_offset;
448 	struct page *page;
449 	struct sk_buff *trailer;
450 	int tailen = esp->tailen;
451 
452 	/* this is non-NULL only with TCP/UDP Encapsulation */
453 	if (x->encap) {
454 		int err = esp_output_encap(x, skb, esp);
455 
456 		if (err < 0)
457 			return err;
458 	}
459 
460 	if (ALIGN(tailen, L1_CACHE_BYTES) > PAGE_SIZE ||
461 	    ALIGN(skb->data_len, L1_CACHE_BYTES) > PAGE_SIZE)
462 		goto cow;
463 
464 	if (!skb_cloned(skb)) {
465 		if (tailen <= skb_tailroom(skb)) {
466 			nfrags = 1;
467 			trailer = skb;
468 			tail = skb_tail_pointer(trailer);
469 
470 			goto skip_cow;
471 		} else if ((skb_shinfo(skb)->nr_frags < MAX_SKB_FRAGS)
472 			   && !skb_has_frag_list(skb)) {
473 			int allocsize;
474 			struct sock *sk = skb->sk;
475 			struct page_frag *pfrag = &x->xfrag;
476 
477 			esp->inplace = false;
478 
479 			allocsize = ALIGN(tailen, L1_CACHE_BYTES);
480 
481 			spin_lock_bh(&x->lock);
482 
483 			if (unlikely(!skb_page_frag_refill(allocsize, pfrag, GFP_ATOMIC))) {
484 				spin_unlock_bh(&x->lock);
485 				goto cow;
486 			}
487 
488 			page = pfrag->page;
489 			get_page(page);
490 
491 			tail = page_address(page) + pfrag->offset;
492 
493 			esp_output_fill_trailer(tail, esp->tfclen, esp->plen, esp->proto);
494 
495 			nfrags = skb_shinfo(skb)->nr_frags;
496 
497 			__skb_fill_page_desc(skb, nfrags, page, pfrag->offset,
498 					     tailen);
499 			skb_shinfo(skb)->nr_frags = ++nfrags;
500 
501 			pfrag->offset = pfrag->offset + allocsize;
502 
503 			spin_unlock_bh(&x->lock);
504 
505 			nfrags++;
506 
507 			skb->len += tailen;
508 			skb->data_len += tailen;
509 			skb->truesize += tailen;
510 			if (sk && sk_fullsock(sk))
511 				refcount_add(tailen, &sk->sk_wmem_alloc);
512 
513 			goto out;
514 		}
515 	}
516 
517 cow:
518 	esph_offset = (unsigned char *)esp->esph - skb_transport_header(skb);
519 
520 	nfrags = skb_cow_data(skb, tailen, &trailer);
521 	if (nfrags < 0)
522 		goto out;
523 	tail = skb_tail_pointer(trailer);
524 	esp->esph = (struct ip_esp_hdr *)(skb_transport_header(skb) + esph_offset);
525 
526 skip_cow:
527 	esp_output_fill_trailer(tail, esp->tfclen, esp->plen, esp->proto);
528 	pskb_put(skb, trailer, tailen);
529 
530 out:
531 	return nfrags;
532 }
533 EXPORT_SYMBOL_GPL(esp_output_head);
534 
esp_output_tail(struct xfrm_state * x,struct sk_buff * skb,struct esp_info * esp)535 int esp_output_tail(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *esp)
536 {
537 	u8 *iv;
538 	int alen;
539 	void *tmp;
540 	int ivlen;
541 	int assoclen;
542 	int extralen;
543 	struct page *page;
544 	struct ip_esp_hdr *esph;
545 	struct crypto_aead *aead;
546 	struct aead_request *req;
547 	struct scatterlist *sg, *dsg;
548 	struct esp_output_extra *extra;
549 	int err = -ENOMEM;
550 
551 	assoclen = sizeof(struct ip_esp_hdr);
552 	extralen = 0;
553 
554 	if (x->props.flags & XFRM_STATE_ESN) {
555 		extralen += sizeof(*extra);
556 		assoclen += sizeof(__be32);
557 	}
558 
559 	aead = x->data;
560 	alen = crypto_aead_authsize(aead);
561 	ivlen = crypto_aead_ivsize(aead);
562 
563 	tmp = esp_alloc_tmp(aead, esp->nfrags + 2, extralen);
564 	if (!tmp)
565 		goto error;
566 
567 	extra = esp_tmp_extra(tmp);
568 	iv = esp_tmp_iv(aead, tmp, extralen);
569 	req = esp_tmp_req(aead, iv);
570 	sg = esp_req_sg(aead, req);
571 
572 	if (esp->inplace)
573 		dsg = sg;
574 	else
575 		dsg = &sg[esp->nfrags];
576 
577 	esph = esp_output_set_extra(skb, x, esp->esph, extra);
578 	esp->esph = esph;
579 
580 	sg_init_table(sg, esp->nfrags);
581 	err = skb_to_sgvec(skb, sg,
582 		           (unsigned char *)esph - skb->data,
583 		           assoclen + ivlen + esp->clen + alen);
584 	if (unlikely(err < 0))
585 		goto error_free;
586 
587 	if (!esp->inplace) {
588 		int allocsize;
589 		struct page_frag *pfrag = &x->xfrag;
590 
591 		allocsize = ALIGN(skb->data_len, L1_CACHE_BYTES);
592 
593 		spin_lock_bh(&x->lock);
594 		if (unlikely(!skb_page_frag_refill(allocsize, pfrag, GFP_ATOMIC))) {
595 			spin_unlock_bh(&x->lock);
596 			goto error_free;
597 		}
598 
599 		skb_shinfo(skb)->nr_frags = 1;
600 
601 		page = pfrag->page;
602 		get_page(page);
603 		/* replace page frags in skb with new page */
604 		__skb_fill_page_desc(skb, 0, page, pfrag->offset, skb->data_len);
605 		pfrag->offset = pfrag->offset + allocsize;
606 		spin_unlock_bh(&x->lock);
607 
608 		sg_init_table(dsg, skb_shinfo(skb)->nr_frags + 1);
609 		err = skb_to_sgvec(skb, dsg,
610 			           (unsigned char *)esph - skb->data,
611 			           assoclen + ivlen + esp->clen + alen);
612 		if (unlikely(err < 0))
613 			goto error_free;
614 	}
615 
616 	if ((x->props.flags & XFRM_STATE_ESN))
617 		aead_request_set_callback(req, 0, esp_output_done_esn, skb);
618 	else
619 		aead_request_set_callback(req, 0, esp_output_done, skb);
620 
621 	aead_request_set_crypt(req, sg, dsg, ivlen + esp->clen, iv);
622 	aead_request_set_ad(req, assoclen);
623 
624 	memset(iv, 0, ivlen);
625 	memcpy(iv + ivlen - min(ivlen, 8), (u8 *)&esp->seqno + 8 - min(ivlen, 8),
626 	       min(ivlen, 8));
627 
628 	ESP_SKB_CB(skb)->tmp = tmp;
629 	err = crypto_aead_encrypt(req);
630 
631 	switch (err) {
632 	case -EINPROGRESS:
633 		goto error;
634 
635 	case -ENOSPC:
636 		err = NET_XMIT_DROP;
637 		break;
638 
639 	case 0:
640 		if ((x->props.flags & XFRM_STATE_ESN))
641 			esp_output_restore_header(skb);
642 	}
643 
644 	if (sg != dsg)
645 		esp_ssg_unref(x, tmp);
646 
647 	if (!err && x->encap && x->encap->encap_type == TCP_ENCAP_ESPINTCP)
648 		err = esp_output_tail_tcp(x, skb);
649 
650 error_free:
651 	kfree(tmp);
652 error:
653 	return err;
654 }
655 EXPORT_SYMBOL_GPL(esp_output_tail);
656 
esp_output(struct xfrm_state * x,struct sk_buff * skb)657 static int esp_output(struct xfrm_state *x, struct sk_buff *skb)
658 {
659 	int alen;
660 	int blksize;
661 	struct ip_esp_hdr *esph;
662 	struct crypto_aead *aead;
663 	struct esp_info esp;
664 
665 	esp.inplace = true;
666 
667 	esp.proto = *skb_mac_header(skb);
668 	*skb_mac_header(skb) = IPPROTO_ESP;
669 
670 	/* skb is pure payload to encrypt */
671 
672 	aead = x->data;
673 	alen = crypto_aead_authsize(aead);
674 
675 	esp.tfclen = 0;
676 	if (x->tfcpad) {
677 		struct xfrm_dst *dst = (struct xfrm_dst *)skb_dst(skb);
678 		u32 padto;
679 
680 		padto = min(x->tfcpad, xfrm_state_mtu(x, dst->child_mtu_cached));
681 		if (skb->len < padto)
682 			esp.tfclen = padto - skb->len;
683 	}
684 	blksize = ALIGN(crypto_aead_blocksize(aead), 4);
685 	esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
686 	esp.plen = esp.clen - skb->len - esp.tfclen;
687 	esp.tailen = esp.tfclen + esp.plen + alen;
688 
689 	esp.esph = ip_esp_hdr(skb);
690 
691 	esp.nfrags = esp_output_head(x, skb, &esp);
692 	if (esp.nfrags < 0)
693 		return esp.nfrags;
694 
695 	esph = esp.esph;
696 	esph->spi = x->id.spi;
697 
698 	esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
699 	esp.seqno = cpu_to_be64(XFRM_SKB_CB(skb)->seq.output.low +
700 				 ((u64)XFRM_SKB_CB(skb)->seq.output.hi << 32));
701 
702 	skb_push(skb, -skb_network_offset(skb));
703 
704 	return esp_output_tail(x, skb, &esp);
705 }
706 
esp_remove_trailer(struct sk_buff * skb)707 static inline int esp_remove_trailer(struct sk_buff *skb)
708 {
709 	struct xfrm_state *x = xfrm_input_state(skb);
710 	struct xfrm_offload *xo = xfrm_offload(skb);
711 	struct crypto_aead *aead = x->data;
712 	int alen, hlen, elen;
713 	int padlen, trimlen;
714 	__wsum csumdiff;
715 	u8 nexthdr[2];
716 	int ret;
717 
718 	alen = crypto_aead_authsize(aead);
719 	hlen = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead);
720 	elen = skb->len - hlen;
721 
722 	if (xo && (xo->flags & XFRM_ESP_NO_TRAILER)) {
723 		ret = xo->proto;
724 		goto out;
725 	}
726 
727 	if (skb_copy_bits(skb, skb->len - alen - 2, nexthdr, 2))
728 		BUG();
729 
730 	ret = -EINVAL;
731 	padlen = nexthdr[0];
732 	if (padlen + 2 + alen >= elen) {
733 		net_dbg_ratelimited("ipsec esp packet is garbage padlen=%d, elen=%d\n",
734 				    padlen + 2, elen - alen);
735 		goto out;
736 	}
737 
738 	trimlen = alen + padlen + 2;
739 	if (skb->ip_summed == CHECKSUM_COMPLETE) {
740 		csumdiff = skb_checksum(skb, skb->len - trimlen, trimlen, 0);
741 		skb->csum = csum_block_sub(skb->csum, csumdiff,
742 					   skb->len - trimlen);
743 	}
744 	ret = pskb_trim(skb, skb->len - trimlen);
745 	if (unlikely(ret))
746 		return ret;
747 
748 	ret = nexthdr[1];
749 
750 out:
751 	return ret;
752 }
753 
esp_input_done2(struct sk_buff * skb,int err)754 int esp_input_done2(struct sk_buff *skb, int err)
755 {
756 	const struct iphdr *iph;
757 	struct xfrm_state *x = xfrm_input_state(skb);
758 	struct xfrm_offload *xo = xfrm_offload(skb);
759 	struct crypto_aead *aead = x->data;
760 	int hlen = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead);
761 	int ihl;
762 
763 	if (!xo || (xo && !(xo->flags & CRYPTO_DONE)))
764 		kfree(ESP_SKB_CB(skb)->tmp);
765 
766 	if (unlikely(err))
767 		goto out;
768 
769 	err = esp_remove_trailer(skb);
770 	if (unlikely(err < 0))
771 		goto out;
772 
773 	iph = ip_hdr(skb);
774 	ihl = iph->ihl * 4;
775 
776 	if (x->encap) {
777 		struct xfrm_encap_tmpl *encap = x->encap;
778 		struct tcphdr *th = (void *)(skb_network_header(skb) + ihl);
779 		struct udphdr *uh = (void *)(skb_network_header(skb) + ihl);
780 		__be16 source;
781 
782 		switch (x->encap->encap_type) {
783 		case TCP_ENCAP_ESPINTCP:
784 			source = th->source;
785 			break;
786 		case UDP_ENCAP_ESPINUDP:
787 		case UDP_ENCAP_ESPINUDP_NON_IKE:
788 			source = uh->source;
789 			break;
790 		default:
791 			WARN_ON_ONCE(1);
792 			err = -EINVAL;
793 			goto out;
794 		}
795 
796 		/*
797 		 * 1) if the NAT-T peer's IP or port changed then
798 		 *    advertize the change to the keying daemon.
799 		 *    This is an inbound SA, so just compare
800 		 *    SRC ports.
801 		 */
802 		if (iph->saddr != x->props.saddr.a4 ||
803 		    source != encap->encap_sport) {
804 			xfrm_address_t ipaddr;
805 
806 			ipaddr.a4 = iph->saddr;
807 			km_new_mapping(x, &ipaddr, source);
808 
809 			/* XXX: perhaps add an extra
810 			 * policy check here, to see
811 			 * if we should allow or
812 			 * reject a packet from a
813 			 * different source
814 			 * address/port.
815 			 */
816 		}
817 
818 		/*
819 		 * 2) ignore UDP/TCP checksums in case
820 		 *    of NAT-T in Transport Mode, or
821 		 *    perform other post-processing fixes
822 		 *    as per draft-ietf-ipsec-udp-encaps-06,
823 		 *    section 3.1.2
824 		 */
825 		if (x->props.mode == XFRM_MODE_TRANSPORT)
826 			skb->ip_summed = CHECKSUM_UNNECESSARY;
827 	}
828 
829 	skb_pull_rcsum(skb, hlen);
830 	if (x->props.mode == XFRM_MODE_TUNNEL)
831 		skb_reset_transport_header(skb);
832 	else
833 		skb_set_transport_header(skb, -ihl);
834 
835 	/* RFC4303: Drop dummy packets without any error */
836 	if (err == IPPROTO_NONE)
837 		err = -EINVAL;
838 
839 out:
840 	return err;
841 }
842 EXPORT_SYMBOL_GPL(esp_input_done2);
843 
esp_input_done(struct crypto_async_request * base,int err)844 static void esp_input_done(struct crypto_async_request *base, int err)
845 {
846 	struct sk_buff *skb = base->data;
847 
848 	xfrm_input_resume(skb, esp_input_done2(skb, err));
849 }
850 
esp_input_restore_header(struct sk_buff * skb)851 static void esp_input_restore_header(struct sk_buff *skb)
852 {
853 	esp_restore_header(skb, 0);
854 	__skb_pull(skb, 4);
855 }
856 
esp_input_set_header(struct sk_buff * skb,__be32 * seqhi)857 static void esp_input_set_header(struct sk_buff *skb, __be32 *seqhi)
858 {
859 	struct xfrm_state *x = xfrm_input_state(skb);
860 	struct ip_esp_hdr *esph;
861 
862 	/* For ESN we move the header forward by 4 bytes to
863 	 * accomodate the high bits.  We will move it back after
864 	 * decryption.
865 	 */
866 	if ((x->props.flags & XFRM_STATE_ESN)) {
867 		esph = skb_push(skb, 4);
868 		*seqhi = esph->spi;
869 		esph->spi = esph->seq_no;
870 		esph->seq_no = XFRM_SKB_CB(skb)->seq.input.hi;
871 	}
872 }
873 
esp_input_done_esn(struct crypto_async_request * base,int err)874 static void esp_input_done_esn(struct crypto_async_request *base, int err)
875 {
876 	struct sk_buff *skb = base->data;
877 
878 	esp_input_restore_header(skb);
879 	esp_input_done(base, err);
880 }
881 
882 /*
883  * Note: detecting truncated vs. non-truncated authentication data is very
884  * expensive, so we only support truncated data, which is the recommended
885  * and common case.
886  */
esp_input(struct xfrm_state * x,struct sk_buff * skb)887 static int esp_input(struct xfrm_state *x, struct sk_buff *skb)
888 {
889 	struct crypto_aead *aead = x->data;
890 	struct aead_request *req;
891 	struct sk_buff *trailer;
892 	int ivlen = crypto_aead_ivsize(aead);
893 	int elen = skb->len - sizeof(struct ip_esp_hdr) - ivlen;
894 	int nfrags;
895 	int assoclen;
896 	int seqhilen;
897 	__be32 *seqhi;
898 	void *tmp;
899 	u8 *iv;
900 	struct scatterlist *sg;
901 	int err = -EINVAL;
902 
903 	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + ivlen))
904 		goto out;
905 
906 	if (elen <= 0)
907 		goto out;
908 
909 	assoclen = sizeof(struct ip_esp_hdr);
910 	seqhilen = 0;
911 
912 	if (x->props.flags & XFRM_STATE_ESN) {
913 		seqhilen += sizeof(__be32);
914 		assoclen += seqhilen;
915 	}
916 
917 	if (!skb_cloned(skb)) {
918 		if (!skb_is_nonlinear(skb)) {
919 			nfrags = 1;
920 
921 			goto skip_cow;
922 		} else if (!skb_has_frag_list(skb)) {
923 			nfrags = skb_shinfo(skb)->nr_frags;
924 			nfrags++;
925 
926 			goto skip_cow;
927 		}
928 	}
929 
930 	err = skb_cow_data(skb, 0, &trailer);
931 	if (err < 0)
932 		goto out;
933 
934 	nfrags = err;
935 
936 skip_cow:
937 	err = -ENOMEM;
938 	tmp = esp_alloc_tmp(aead, nfrags, seqhilen);
939 	if (!tmp)
940 		goto out;
941 
942 	ESP_SKB_CB(skb)->tmp = tmp;
943 	seqhi = esp_tmp_extra(tmp);
944 	iv = esp_tmp_iv(aead, tmp, seqhilen);
945 	req = esp_tmp_req(aead, iv);
946 	sg = esp_req_sg(aead, req);
947 
948 	esp_input_set_header(skb, seqhi);
949 
950 	sg_init_table(sg, nfrags);
951 	err = skb_to_sgvec(skb, sg, 0, skb->len);
952 	if (unlikely(err < 0)) {
953 		kfree(tmp);
954 		goto out;
955 	}
956 
957 	skb->ip_summed = CHECKSUM_NONE;
958 
959 	if ((x->props.flags & XFRM_STATE_ESN))
960 		aead_request_set_callback(req, 0, esp_input_done_esn, skb);
961 	else
962 		aead_request_set_callback(req, 0, esp_input_done, skb);
963 
964 	aead_request_set_crypt(req, sg, sg, elen + ivlen, iv);
965 	aead_request_set_ad(req, assoclen);
966 
967 	err = crypto_aead_decrypt(req);
968 	if (err == -EINPROGRESS)
969 		goto out;
970 
971 	if ((x->props.flags & XFRM_STATE_ESN))
972 		esp_input_restore_header(skb);
973 
974 	err = esp_input_done2(skb, err);
975 
976 out:
977 	return err;
978 }
979 
esp4_err(struct sk_buff * skb,u32 info)980 static int esp4_err(struct sk_buff *skb, u32 info)
981 {
982 	struct net *net = dev_net(skb->dev);
983 	const struct iphdr *iph = (const struct iphdr *)skb->data;
984 	struct ip_esp_hdr *esph = (struct ip_esp_hdr *)(skb->data+(iph->ihl<<2));
985 	struct xfrm_state *x;
986 
987 	switch (icmp_hdr(skb)->type) {
988 	case ICMP_DEST_UNREACH:
989 		if (icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
990 			return 0;
991 	case ICMP_REDIRECT:
992 		break;
993 	default:
994 		return 0;
995 	}
996 
997 	x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
998 			      esph->spi, IPPROTO_ESP, AF_INET);
999 	if (!x)
1000 		return 0;
1001 
1002 	if (icmp_hdr(skb)->type == ICMP_DEST_UNREACH)
1003 		ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ESP);
1004 	else
1005 		ipv4_redirect(skb, net, 0, IPPROTO_ESP);
1006 	xfrm_state_put(x);
1007 
1008 	return 0;
1009 }
1010 
esp_destroy(struct xfrm_state * x)1011 static void esp_destroy(struct xfrm_state *x)
1012 {
1013 	struct crypto_aead *aead = x->data;
1014 
1015 	if (!aead)
1016 		return;
1017 
1018 	crypto_free_aead(aead);
1019 }
1020 
esp_init_aead(struct xfrm_state * x)1021 static int esp_init_aead(struct xfrm_state *x)
1022 {
1023 	char aead_name[CRYPTO_MAX_ALG_NAME];
1024 	struct crypto_aead *aead;
1025 	int err;
1026 
1027 	err = -ENAMETOOLONG;
1028 	if (snprintf(aead_name, CRYPTO_MAX_ALG_NAME, "%s(%s)",
1029 		     x->geniv, x->aead->alg_name) >= CRYPTO_MAX_ALG_NAME)
1030 		goto error;
1031 
1032 	aead = crypto_alloc_aead(aead_name, 0, 0);
1033 	err = PTR_ERR(aead);
1034 	if (IS_ERR(aead))
1035 		goto error;
1036 
1037 	x->data = aead;
1038 
1039 	err = crypto_aead_setkey(aead, x->aead->alg_key,
1040 				 (x->aead->alg_key_len + 7) / 8);
1041 	if (err)
1042 		goto error;
1043 
1044 	err = crypto_aead_setauthsize(aead, x->aead->alg_icv_len / 8);
1045 	if (err)
1046 		goto error;
1047 
1048 error:
1049 	return err;
1050 }
1051 
esp_init_authenc(struct xfrm_state * x)1052 static int esp_init_authenc(struct xfrm_state *x)
1053 {
1054 	struct crypto_aead *aead;
1055 	struct crypto_authenc_key_param *param;
1056 	struct rtattr *rta;
1057 	char *key;
1058 	char *p;
1059 	char authenc_name[CRYPTO_MAX_ALG_NAME];
1060 	unsigned int keylen;
1061 	int err;
1062 
1063 	err = -EINVAL;
1064 	if (!x->ealg)
1065 		goto error;
1066 
1067 	err = -ENAMETOOLONG;
1068 
1069 	if ((x->props.flags & XFRM_STATE_ESN)) {
1070 		if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME,
1071 			     "%s%sauthencesn(%s,%s)%s",
1072 			     x->geniv ?: "", x->geniv ? "(" : "",
1073 			     x->aalg ? x->aalg->alg_name : "digest_null",
1074 			     x->ealg->alg_name,
1075 			     x->geniv ? ")" : "") >= CRYPTO_MAX_ALG_NAME)
1076 			goto error;
1077 	} else {
1078 		if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME,
1079 			     "%s%sauthenc(%s,%s)%s",
1080 			     x->geniv ?: "", x->geniv ? "(" : "",
1081 			     x->aalg ? x->aalg->alg_name : "digest_null",
1082 			     x->ealg->alg_name,
1083 			     x->geniv ? ")" : "") >= CRYPTO_MAX_ALG_NAME)
1084 			goto error;
1085 	}
1086 
1087 	aead = crypto_alloc_aead(authenc_name, 0, 0);
1088 	err = PTR_ERR(aead);
1089 	if (IS_ERR(aead))
1090 		goto error;
1091 
1092 	x->data = aead;
1093 
1094 	keylen = (x->aalg ? (x->aalg->alg_key_len + 7) / 8 : 0) +
1095 		 (x->ealg->alg_key_len + 7) / 8 + RTA_SPACE(sizeof(*param));
1096 	err = -ENOMEM;
1097 	key = kmalloc(keylen, GFP_KERNEL);
1098 	if (!key)
1099 		goto error;
1100 
1101 	p = key;
1102 	rta = (void *)p;
1103 	rta->rta_type = CRYPTO_AUTHENC_KEYA_PARAM;
1104 	rta->rta_len = RTA_LENGTH(sizeof(*param));
1105 	param = RTA_DATA(rta);
1106 	p += RTA_SPACE(sizeof(*param));
1107 
1108 	if (x->aalg) {
1109 		struct xfrm_algo_desc *aalg_desc;
1110 
1111 		memcpy(p, x->aalg->alg_key, (x->aalg->alg_key_len + 7) / 8);
1112 		p += (x->aalg->alg_key_len + 7) / 8;
1113 
1114 		aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
1115 		BUG_ON(!aalg_desc);
1116 
1117 		err = -EINVAL;
1118 		if (aalg_desc->uinfo.auth.icv_fullbits / 8 !=
1119 		    crypto_aead_authsize(aead)) {
1120 			pr_info("ESP: %s digestsize %u != %hu\n",
1121 				x->aalg->alg_name,
1122 				crypto_aead_authsize(aead),
1123 				aalg_desc->uinfo.auth.icv_fullbits / 8);
1124 			goto free_key;
1125 		}
1126 
1127 		err = crypto_aead_setauthsize(
1128 			aead, x->aalg->alg_trunc_len / 8);
1129 		if (err)
1130 			goto free_key;
1131 	}
1132 
1133 	param->enckeylen = cpu_to_be32((x->ealg->alg_key_len + 7) / 8);
1134 	memcpy(p, x->ealg->alg_key, (x->ealg->alg_key_len + 7) / 8);
1135 
1136 	err = crypto_aead_setkey(aead, key, keylen);
1137 
1138 free_key:
1139 	kfree_sensitive(key);
1140 
1141 error:
1142 	return err;
1143 }
1144 
esp_init_state(struct xfrm_state * x)1145 static int esp_init_state(struct xfrm_state *x)
1146 {
1147 	struct crypto_aead *aead;
1148 	u32 align;
1149 	int err;
1150 
1151 	x->data = NULL;
1152 
1153 	if (x->aead)
1154 		err = esp_init_aead(x);
1155 	else
1156 		err = esp_init_authenc(x);
1157 
1158 	if (err)
1159 		goto error;
1160 
1161 	aead = x->data;
1162 
1163 	x->props.header_len = sizeof(struct ip_esp_hdr) +
1164 			      crypto_aead_ivsize(aead);
1165 	if (x->props.mode == XFRM_MODE_TUNNEL)
1166 		x->props.header_len += sizeof(struct iphdr);
1167 	else if (x->props.mode == XFRM_MODE_BEET && x->sel.family != AF_INET6)
1168 		x->props.header_len += IPV4_BEET_PHMAXLEN;
1169 	if (x->encap) {
1170 		struct xfrm_encap_tmpl *encap = x->encap;
1171 
1172 		switch (encap->encap_type) {
1173 		default:
1174 			err = -EINVAL;
1175 			goto error;
1176 		case UDP_ENCAP_ESPINUDP:
1177 			x->props.header_len += sizeof(struct udphdr);
1178 			break;
1179 		case UDP_ENCAP_ESPINUDP_NON_IKE:
1180 			x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32);
1181 			break;
1182 #ifdef CONFIG_INET_ESPINTCP
1183 		case TCP_ENCAP_ESPINTCP:
1184 			/* only the length field, TCP encap is done by
1185 			 * the socket
1186 			 */
1187 			x->props.header_len += 2;
1188 			break;
1189 #endif
1190 		}
1191 	}
1192 
1193 	align = ALIGN(crypto_aead_blocksize(aead), 4);
1194 	x->props.trailer_len = align + 1 + crypto_aead_authsize(aead);
1195 
1196 error:
1197 	return err;
1198 }
1199 
esp4_rcv_cb(struct sk_buff * skb,int err)1200 static int esp4_rcv_cb(struct sk_buff *skb, int err)
1201 {
1202 	return 0;
1203 }
1204 
1205 static const struct xfrm_type esp_type =
1206 {
1207 	.description	= "ESP4",
1208 	.owner		= THIS_MODULE,
1209 	.proto	     	= IPPROTO_ESP,
1210 	.flags		= XFRM_TYPE_REPLAY_PROT,
1211 	.init_state	= esp_init_state,
1212 	.destructor	= esp_destroy,
1213 	.input		= esp_input,
1214 	.output		= esp_output,
1215 };
1216 
1217 static struct xfrm4_protocol esp4_protocol = {
1218 	.handler	=	xfrm4_rcv,
1219 	.input_handler	=	xfrm_input,
1220 	.cb_handler	=	esp4_rcv_cb,
1221 	.err_handler	=	esp4_err,
1222 	.priority	=	0,
1223 };
1224 
esp4_init(void)1225 static int __init esp4_init(void)
1226 {
1227 	if (xfrm_register_type(&esp_type, AF_INET) < 0) {
1228 		pr_info("%s: can't add xfrm type\n", __func__);
1229 		return -EAGAIN;
1230 	}
1231 	if (xfrm4_protocol_register(&esp4_protocol, IPPROTO_ESP) < 0) {
1232 		pr_info("%s: can't add protocol\n", __func__);
1233 		xfrm_unregister_type(&esp_type, AF_INET);
1234 		return -EAGAIN;
1235 	}
1236 	return 0;
1237 }
1238 
esp4_fini(void)1239 static void __exit esp4_fini(void)
1240 {
1241 	if (xfrm4_protocol_deregister(&esp4_protocol, IPPROTO_ESP) < 0)
1242 		pr_info("%s: can't remove protocol\n", __func__);
1243 	xfrm_unregister_type(&esp_type, AF_INET);
1244 }
1245 
1246 module_init(esp4_init);
1247 module_exit(esp4_fini);
1248 MODULE_LICENSE("GPL");
1249 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_ESP);
1250