1/* Copyright (c) 2018, Mellanox Technologies All rights reserved.
2 *
3 * This software is available to you under a choice of one of two
4 * licenses.  You may choose to be licensed under the terms of the GNU
5 * General Public License (GPL) Version 2, available from the file
6 * COPYING in the main directory of this source tree, or the
7 * OpenIB.org BSD license below:
8 *
9 *     Redistribution and use in source and binary forms, with or
10 *     without modification, are permitted provided that the following
11 *     conditions are met:
12 *
13 *      - Redistributions of source code must retain the above
14 *        copyright notice, this list of conditions and the following
15 *        disclaimer.
16 *
17 *      - Redistributions in binary form must reproduce the above
18 *        copyright notice, this list of conditions and the following
19 *        disclaimer in the documentation and/or other materials
20 *        provided with the distribution.
21 *
22 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
23 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
24 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
25 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
26 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
27 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
28 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
29 * SOFTWARE.
30 */
31
32#include <net/tls.h>
33#include <crypto/aead.h>
34#include <crypto/scatterwalk.h>
35#include <net/ip6_checksum.h>
36
37#include "tls.h"
38
39static void chain_to_walk(struct scatterlist *sg, struct scatter_walk *walk)
40{
41	struct scatterlist *src = walk->sg;
42	int diff = walk->offset - src->offset;
43
44	sg_set_page(sg, sg_page(src),
45		    src->length - diff, walk->offset);
46
47	scatterwalk_crypto_chain(sg, sg_next(src), 2);
48}
49
50static int tls_enc_record(struct aead_request *aead_req,
51			  struct crypto_aead *aead, char *aad,
52			  char *iv, __be64 rcd_sn,
53			  struct scatter_walk *in,
54			  struct scatter_walk *out, int *in_len,
55			  struct tls_prot_info *prot)
56{
57	unsigned char buf[TLS_HEADER_SIZE + TLS_MAX_IV_SIZE];
58	const struct tls_cipher_desc *cipher_desc;
59	struct scatterlist sg_in[3];
60	struct scatterlist sg_out[3];
61	unsigned int buf_size;
62	u16 len;
63	int rc;
64
65	cipher_desc = get_cipher_desc(prot->cipher_type);
66	DEBUG_NET_WARN_ON_ONCE(!cipher_desc || !cipher_desc->offloadable);
67
68	buf_size = TLS_HEADER_SIZE + cipher_desc->iv;
69	len = min_t(int, *in_len, buf_size);
70
71	scatterwalk_copychunks(buf, in, len, 0);
72	scatterwalk_copychunks(buf, out, len, 1);
73
74	*in_len -= len;
75	if (!*in_len)
76		return 0;
77
78	scatterwalk_pagedone(in, 0, 1);
79	scatterwalk_pagedone(out, 1, 1);
80
81	len = buf[4] | (buf[3] << 8);
82	len -= cipher_desc->iv;
83
84	tls_make_aad(aad, len - cipher_desc->tag, (char *)&rcd_sn, buf[0], prot);
85
86	memcpy(iv + cipher_desc->salt, buf + TLS_HEADER_SIZE, cipher_desc->iv);
87
88	sg_init_table(sg_in, ARRAY_SIZE(sg_in));
89	sg_init_table(sg_out, ARRAY_SIZE(sg_out));
90	sg_set_buf(sg_in, aad, TLS_AAD_SPACE_SIZE);
91	sg_set_buf(sg_out, aad, TLS_AAD_SPACE_SIZE);
92	chain_to_walk(sg_in + 1, in);
93	chain_to_walk(sg_out + 1, out);
94
95	*in_len -= len;
96	if (*in_len < 0) {
97		*in_len += cipher_desc->tag;
98		/* the input buffer doesn't contain the entire record.
99		 * trim len accordingly. The resulting authentication tag
100		 * will contain garbage, but we don't care, so we won't
101		 * include any of it in the output skb
102		 * Note that we assume the output buffer length
103		 * is larger then input buffer length + tag size
104		 */
105		if (*in_len < 0)
106			len += *in_len;
107
108		*in_len = 0;
109	}
110
111	if (*in_len) {
112		scatterwalk_copychunks(NULL, in, len, 2);
113		scatterwalk_pagedone(in, 0, 1);
114		scatterwalk_copychunks(NULL, out, len, 2);
115		scatterwalk_pagedone(out, 1, 1);
116	}
117
118	len -= cipher_desc->tag;
119	aead_request_set_crypt(aead_req, sg_in, sg_out, len, iv);
120
121	rc = crypto_aead_encrypt(aead_req);
122
123	return rc;
124}
125
126static void tls_init_aead_request(struct aead_request *aead_req,
127				  struct crypto_aead *aead)
128{
129	aead_request_set_tfm(aead_req, aead);
130	aead_request_set_ad(aead_req, TLS_AAD_SPACE_SIZE);
131}
132
133static struct aead_request *tls_alloc_aead_request(struct crypto_aead *aead,
134						   gfp_t flags)
135{
136	unsigned int req_size = sizeof(struct aead_request) +
137		crypto_aead_reqsize(aead);
138	struct aead_request *aead_req;
139
140	aead_req = kzalloc(req_size, flags);
141	if (aead_req)
142		tls_init_aead_request(aead_req, aead);
143	return aead_req;
144}
145
146static int tls_enc_records(struct aead_request *aead_req,
147			   struct crypto_aead *aead, struct scatterlist *sg_in,
148			   struct scatterlist *sg_out, char *aad, char *iv,
149			   u64 rcd_sn, int len, struct tls_prot_info *prot)
150{
151	struct scatter_walk out, in;
152	int rc;
153
154	scatterwalk_start(&in, sg_in);
155	scatterwalk_start(&out, sg_out);
156
157	do {
158		rc = tls_enc_record(aead_req, aead, aad, iv,
159				    cpu_to_be64(rcd_sn), &in, &out, &len, prot);
160		rcd_sn++;
161
162	} while (rc == 0 && len);
163
164	scatterwalk_done(&in, 0, 0);
165	scatterwalk_done(&out, 1, 0);
166
167	return rc;
168}
169
170/* Can't use icsk->icsk_af_ops->send_check here because the ip addresses
171 * might have been changed by NAT.
172 */
173static void update_chksum(struct sk_buff *skb, int headln)
174{
175	struct tcphdr *th = tcp_hdr(skb);
176	int datalen = skb->len - headln;
177	const struct ipv6hdr *ipv6h;
178	const struct iphdr *iph;
179
180	/* We only changed the payload so if we are using partial we don't
181	 * need to update anything.
182	 */
183	if (likely(skb->ip_summed == CHECKSUM_PARTIAL))
184		return;
185
186	skb->ip_summed = CHECKSUM_PARTIAL;
187	skb->csum_start = skb_transport_header(skb) - skb->head;
188	skb->csum_offset = offsetof(struct tcphdr, check);
189
190	if (skb->sk->sk_family == AF_INET6) {
191		ipv6h = ipv6_hdr(skb);
192		th->check = ~csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr,
193					     datalen, IPPROTO_TCP, 0);
194	} else {
195		iph = ip_hdr(skb);
196		th->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr, datalen,
197					       IPPROTO_TCP, 0);
198	}
199}
200
201static void complete_skb(struct sk_buff *nskb, struct sk_buff *skb, int headln)
202{
203	struct sock *sk = skb->sk;
204	int delta;
205
206	skb_copy_header(nskb, skb);
207
208	skb_put(nskb, skb->len);
209	memcpy(nskb->data, skb->data, headln);
210
211	nskb->destructor = skb->destructor;
212	nskb->sk = sk;
213	skb->destructor = NULL;
214	skb->sk = NULL;
215
216	update_chksum(nskb, headln);
217
218	/* sock_efree means skb must gone through skb_orphan_partial() */
219	if (nskb->destructor == sock_efree)
220		return;
221
222	delta = nskb->truesize - skb->truesize;
223	if (likely(delta < 0))
224		WARN_ON_ONCE(refcount_sub_and_test(-delta, &sk->sk_wmem_alloc));
225	else if (delta)
226		refcount_add(delta, &sk->sk_wmem_alloc);
227}
228
229/* This function may be called after the user socket is already
230 * closed so make sure we don't use anything freed during
231 * tls_sk_proto_close here
232 */
233
234static int fill_sg_in(struct scatterlist *sg_in,
235		      struct sk_buff *skb,
236		      struct tls_offload_context_tx *ctx,
237		      u64 *rcd_sn,
238		      s32 *sync_size,
239		      int *resync_sgs)
240{
241	int tcp_payload_offset = skb_tcp_all_headers(skb);
242	int payload_len = skb->len - tcp_payload_offset;
243	u32 tcp_seq = ntohl(tcp_hdr(skb)->seq);
244	struct tls_record_info *record;
245	unsigned long flags;
246	int remaining;
247	int i;
248
249	spin_lock_irqsave(&ctx->lock, flags);
250	record = tls_get_record(ctx, tcp_seq, rcd_sn);
251	if (!record) {
252		spin_unlock_irqrestore(&ctx->lock, flags);
253		return -EINVAL;
254	}
255
256	*sync_size = tcp_seq - tls_record_start_seq(record);
257	if (*sync_size < 0) {
258		int is_start_marker = tls_record_is_start_marker(record);
259
260		spin_unlock_irqrestore(&ctx->lock, flags);
261		/* This should only occur if the relevant record was
262		 * already acked. In that case it should be ok
263		 * to drop the packet and avoid retransmission.
264		 *
265		 * There is a corner case where the packet contains
266		 * both an acked and a non-acked record.
267		 * We currently don't handle that case and rely
268		 * on TCP to retransmit a packet that doesn't contain
269		 * already acked payload.
270		 */
271		if (!is_start_marker)
272			*sync_size = 0;
273		return -EINVAL;
274	}
275
276	remaining = *sync_size;
277	for (i = 0; remaining > 0; i++) {
278		skb_frag_t *frag = &record->frags[i];
279
280		__skb_frag_ref(frag);
281		sg_set_page(sg_in + i, skb_frag_page(frag),
282			    skb_frag_size(frag), skb_frag_off(frag));
283
284		remaining -= skb_frag_size(frag);
285
286		if (remaining < 0)
287			sg_in[i].length += remaining;
288	}
289	*resync_sgs = i;
290
291	spin_unlock_irqrestore(&ctx->lock, flags);
292	if (skb_to_sgvec(skb, &sg_in[i], tcp_payload_offset, payload_len) < 0)
293		return -EINVAL;
294
295	return 0;
296}
297
298static void fill_sg_out(struct scatterlist sg_out[3], void *buf,
299			struct tls_context *tls_ctx,
300			struct sk_buff *nskb,
301			int tcp_payload_offset,
302			int payload_len,
303			int sync_size,
304			void *dummy_buf)
305{
306	const struct tls_cipher_desc *cipher_desc =
307		get_cipher_desc(tls_ctx->crypto_send.info.cipher_type);
308
309	sg_set_buf(&sg_out[0], dummy_buf, sync_size);
310	sg_set_buf(&sg_out[1], nskb->data + tcp_payload_offset, payload_len);
311	/* Add room for authentication tag produced by crypto */
312	dummy_buf += sync_size;
313	sg_set_buf(&sg_out[2], dummy_buf, cipher_desc->tag);
314}
315
316static struct sk_buff *tls_enc_skb(struct tls_context *tls_ctx,
317				   struct scatterlist sg_out[3],
318				   struct scatterlist *sg_in,
319				   struct sk_buff *skb,
320				   s32 sync_size, u64 rcd_sn)
321{
322	struct tls_offload_context_tx *ctx = tls_offload_ctx_tx(tls_ctx);
323	int tcp_payload_offset = skb_tcp_all_headers(skb);
324	int payload_len = skb->len - tcp_payload_offset;
325	const struct tls_cipher_desc *cipher_desc;
326	void *buf, *iv, *aad, *dummy_buf, *salt;
327	struct aead_request *aead_req;
328	struct sk_buff *nskb = NULL;
329	int buf_len;
330
331	aead_req = tls_alloc_aead_request(ctx->aead_send, GFP_ATOMIC);
332	if (!aead_req)
333		return NULL;
334
335	cipher_desc = get_cipher_desc(tls_ctx->crypto_send.info.cipher_type);
336	DEBUG_NET_WARN_ON_ONCE(!cipher_desc || !cipher_desc->offloadable);
337
338	buf_len = cipher_desc->salt + cipher_desc->iv + TLS_AAD_SPACE_SIZE +
339		  sync_size + cipher_desc->tag;
340	buf = kmalloc(buf_len, GFP_ATOMIC);
341	if (!buf)
342		goto free_req;
343
344	iv = buf;
345	salt = crypto_info_salt(&tls_ctx->crypto_send.info, cipher_desc);
346	memcpy(iv, salt, cipher_desc->salt);
347	aad = buf + cipher_desc->salt + cipher_desc->iv;
348	dummy_buf = aad + TLS_AAD_SPACE_SIZE;
349
350	nskb = alloc_skb(skb_headroom(skb) + skb->len, GFP_ATOMIC);
351	if (!nskb)
352		goto free_buf;
353
354	skb_reserve(nskb, skb_headroom(skb));
355
356	fill_sg_out(sg_out, buf, tls_ctx, nskb, tcp_payload_offset,
357		    payload_len, sync_size, dummy_buf);
358
359	if (tls_enc_records(aead_req, ctx->aead_send, sg_in, sg_out, aad, iv,
360			    rcd_sn, sync_size + payload_len,
361			    &tls_ctx->prot_info) < 0)
362		goto free_nskb;
363
364	complete_skb(nskb, skb, tcp_payload_offset);
365
366	/* validate_xmit_skb_list assumes that if the skb wasn't segmented
367	 * nskb->prev will point to the skb itself
368	 */
369	nskb->prev = nskb;
370
371free_buf:
372	kfree(buf);
373free_req:
374	kfree(aead_req);
375	return nskb;
376free_nskb:
377	kfree_skb(nskb);
378	nskb = NULL;
379	goto free_buf;
380}
381
382static struct sk_buff *tls_sw_fallback(struct sock *sk, struct sk_buff *skb)
383{
384	int tcp_payload_offset = skb_tcp_all_headers(skb);
385	struct tls_context *tls_ctx = tls_get_ctx(sk);
386	struct tls_offload_context_tx *ctx = tls_offload_ctx_tx(tls_ctx);
387	int payload_len = skb->len - tcp_payload_offset;
388	struct scatterlist *sg_in, sg_out[3];
389	struct sk_buff *nskb = NULL;
390	int sg_in_max_elements;
391	int resync_sgs = 0;
392	s32 sync_size = 0;
393	u64 rcd_sn;
394
395	/* worst case is:
396	 * MAX_SKB_FRAGS in tls_record_info
397	 * MAX_SKB_FRAGS + 1 in SKB head and frags.
398	 */
399	sg_in_max_elements = 2 * MAX_SKB_FRAGS + 1;
400
401	if (!payload_len)
402		return skb;
403
404	sg_in = kmalloc_array(sg_in_max_elements, sizeof(*sg_in), GFP_ATOMIC);
405	if (!sg_in)
406		goto free_orig;
407
408	sg_init_table(sg_in, sg_in_max_elements);
409	sg_init_table(sg_out, ARRAY_SIZE(sg_out));
410
411	if (fill_sg_in(sg_in, skb, ctx, &rcd_sn, &sync_size, &resync_sgs)) {
412		/* bypass packets before kernel TLS socket option was set */
413		if (sync_size < 0 && payload_len <= -sync_size)
414			nskb = skb_get(skb);
415		goto put_sg;
416	}
417
418	nskb = tls_enc_skb(tls_ctx, sg_out, sg_in, skb, sync_size, rcd_sn);
419
420put_sg:
421	while (resync_sgs)
422		put_page(sg_page(&sg_in[--resync_sgs]));
423	kfree(sg_in);
424free_orig:
425	if (nskb)
426		consume_skb(skb);
427	else
428		kfree_skb(skb);
429	return nskb;
430}
431
432struct sk_buff *tls_validate_xmit_skb(struct sock *sk,
433				      struct net_device *dev,
434				      struct sk_buff *skb)
435{
436	if (dev == rcu_dereference_bh(tls_get_ctx(sk)->netdev) ||
437	    netif_is_bond_master(dev))
438		return skb;
439
440	return tls_sw_fallback(sk, skb);
441}
442EXPORT_SYMBOL_GPL(tls_validate_xmit_skb);
443
444struct sk_buff *tls_validate_xmit_skb_sw(struct sock *sk,
445					 struct net_device *dev,
446					 struct sk_buff *skb)
447{
448	return tls_sw_fallback(sk, skb);
449}
450
451struct sk_buff *tls_encrypt_skb(struct sk_buff *skb)
452{
453	return tls_sw_fallback(skb->sk, skb);
454}
455EXPORT_SYMBOL_GPL(tls_encrypt_skb);
456
457int tls_sw_fallback_init(struct sock *sk,
458			 struct tls_offload_context_tx *offload_ctx,
459			 struct tls_crypto_info *crypto_info)
460{
461	const struct tls_cipher_desc *cipher_desc;
462	int rc;
463
464	cipher_desc = get_cipher_desc(crypto_info->cipher_type);
465	if (!cipher_desc || !cipher_desc->offloadable)
466		return -EINVAL;
467
468	offload_ctx->aead_send =
469	    crypto_alloc_aead(cipher_desc->cipher_name, 0, CRYPTO_ALG_ASYNC);
470	if (IS_ERR(offload_ctx->aead_send)) {
471		rc = PTR_ERR(offload_ctx->aead_send);
472		pr_err_ratelimited("crypto_alloc_aead failed rc=%d\n", rc);
473		offload_ctx->aead_send = NULL;
474		goto err_out;
475	}
476
477	rc = crypto_aead_setkey(offload_ctx->aead_send,
478				crypto_info_key(crypto_info, cipher_desc),
479				cipher_desc->key);
480	if (rc)
481		goto free_aead;
482
483	rc = crypto_aead_setauthsize(offload_ctx->aead_send, cipher_desc->tag);
484	if (rc)
485		goto free_aead;
486
487	return 0;
488free_aead:
489	crypto_free_aead(offload_ctx->aead_send);
490err_out:
491	return rc;
492}
493