xref: /linux/net/ipv6/esp6_offload.c (revision 140eb5227767c6754742020a16d2691222b9c19b) 
1 /*
2  * IPV6 GSO/GRO offload support
3  * Linux INET implementation
4  *
5  * Copyright (C) 2016 secunet Security Networks AG
6  * Author: Steffen Klassert <steffen.klassert@secunet.com>
7  *
8  * This program is free software; you can redistribute it and/or modify it
9  * under the terms and conditions of the GNU General Public License,
10  * version 2, as published by the Free Software Foundation.
11  *
12  * ESP GRO support
13  */
14 
15 #include <linux/skbuff.h>
16 #include <linux/init.h>
17 #include <net/protocol.h>
18 #include <crypto/aead.h>
19 #include <crypto/authenc.h>
20 #include <linux/err.h>
21 #include <linux/module.h>
22 #include <net/ip.h>
23 #include <net/xfrm.h>
24 #include <net/esp.h>
25 #include <linux/scatterlist.h>
26 #include <linux/kernel.h>
27 #include <linux/slab.h>
28 #include <linux/spinlock.h>
29 #include <net/ip6_route.h>
30 #include <net/ipv6.h>
31 #include <linux/icmpv6.h>
32 
33 static __u16 esp6_nexthdr_esp_offset(struct ipv6hdr *ipv6_hdr, int nhlen)
34 {
35 	int off = sizeof(struct ipv6hdr);
36 	struct ipv6_opt_hdr *exthdr;
37 
38 	if (likely(ipv6_hdr->nexthdr == NEXTHDR_ESP))
39 		return offsetof(struct ipv6hdr, nexthdr);
40 
41 	while (off < nhlen) {
42 		exthdr = (void *)ipv6_hdr + off;
43 		if (exthdr->nexthdr == NEXTHDR_ESP)
44 			return off;
45 
46 		off += ipv6_optlen(exthdr);
47 	}
48 
49 	return 0;
50 }
51 
52 static struct sk_buff **esp6_gro_receive(struct sk_buff **head,
53 					 struct sk_buff *skb)
54 {
55 	int offset = skb_gro_offset(skb);
56 	struct xfrm_offload *xo;
57 	struct xfrm_state *x;
58 	__be32 seq;
59 	__be32 spi;
60 	int nhoff;
61 	int err;
62 
63 	if (!pskb_pull(skb, offset))
64 		return NULL;
65 
66 	if ((err = xfrm_parse_spi(skb, IPPROTO_ESP, &spi, &seq)) != 0)
67 		goto out;
68 
69 	xo = xfrm_offload(skb);
70 	if (!xo || !(xo->flags & CRYPTO_DONE)) {
71 		err = secpath_set(skb);
72 		if (err)
73 			goto out;
74 
75 		if (skb->sp->len == XFRM_MAX_DEPTH)
76 			goto out;
77 
78 		x = xfrm_state_lookup(dev_net(skb->dev), skb->mark,
79 				      (xfrm_address_t *)&ipv6_hdr(skb)->daddr,
80 				      spi, IPPROTO_ESP, AF_INET6);
81 		if (!x)
82 			goto out;
83 
84 		skb->sp->xvec[skb->sp->len++] = x;
85 		skb->sp->olen++;
86 
87 		xo = xfrm_offload(skb);
88 		if (!xo) {
89 			xfrm_state_put(x);
90 			goto out;
91 		}
92 	}
93 
94 	xo->flags |= XFRM_GRO;
95 
96 	nhoff = esp6_nexthdr_esp_offset(ipv6_hdr(skb), offset);
97 	if (!nhoff)
98 		goto out;
99 
100 	IP6CB(skb)->nhoff = nhoff;
101 	XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6 = NULL;
102 	XFRM_SPI_SKB_CB(skb)->family = AF_INET6;
103 	XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct ipv6hdr, daddr);
104 	XFRM_SPI_SKB_CB(skb)->seq = seq;
105 
106 	/* We don't need to handle errors from xfrm_input, it does all
107 	 * the error handling and frees the resources on error. */
108 	xfrm_input(skb, IPPROTO_ESP, spi, -2);
109 
110 	return ERR_PTR(-EINPROGRESS);
111 out:
112 	skb_push(skb, offset);
113 	NAPI_GRO_CB(skb)->same_flow = 0;
114 	NAPI_GRO_CB(skb)->flush = 1;
115 
116 	return NULL;
117 }
118 
119 static void esp6_gso_encap(struct xfrm_state *x, struct sk_buff *skb)
120 {
121 	struct ip_esp_hdr *esph;
122 	struct ipv6hdr *iph = ipv6_hdr(skb);
123 	struct xfrm_offload *xo = xfrm_offload(skb);
124 	int proto = iph->nexthdr;
125 
126 	skb_push(skb, -skb_network_offset(skb));
127 	esph = ip_esp_hdr(skb);
128 	*skb_mac_header(skb) = IPPROTO_ESP;
129 
130 	esph->spi = x->id.spi;
131 	esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
132 
133 	xo->proto = proto;
134 }
135 
136 static struct sk_buff *esp6_gso_segment(struct sk_buff *skb,
137 				        netdev_features_t features)
138 {
139 	__u32 seq;
140 	int err = 0;
141 	struct sk_buff *skb2;
142 	struct xfrm_state *x;
143 	struct ip_esp_hdr *esph;
144 	struct crypto_aead *aead;
145 	struct sk_buff *segs = ERR_PTR(-EINVAL);
146 	netdev_features_t esp_features = features;
147 	struct xfrm_offload *xo = xfrm_offload(skb);
148 
149 	if (!xo)
150 		goto out;
151 
152 	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_ESP))
153 		goto out;
154 
155 	seq = xo->seq.low;
156 
157 	x = skb->sp->xvec[skb->sp->len - 1];
158 	aead = x->data;
159 	esph = ip_esp_hdr(skb);
160 
161 	if (esph->spi != x->id.spi)
162 		goto out;
163 
164 	if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
165 		goto out;
166 
167 	__skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
168 
169 	skb->encap_hdr_csum = 1;
170 
171 	if (!(features & NETIF_F_HW_ESP))
172 		esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK);
173 
174 	segs = x->outer_mode->gso_segment(x, skb, esp_features);
175 	if (IS_ERR_OR_NULL(segs))
176 		goto out;
177 
178 	__skb_pull(skb, skb->data - skb_mac_header(skb));
179 
180 	skb2 = segs;
181 	do {
182 		struct sk_buff *nskb = skb2->next;
183 
184 		xo = xfrm_offload(skb2);
185 		xo->flags |= XFRM_GSO_SEGMENT;
186 		xo->seq.low = seq;
187 		xo->seq.hi = xfrm_replay_seqhi(x, seq);
188 
189 		if(!(features & NETIF_F_HW_ESP))
190 			xo->flags |= CRYPTO_FALLBACK;
191 
192 		x->outer_mode->xmit(x, skb2);
193 
194 		err = x->type_offload->xmit(x, skb2, esp_features);
195 		if (err) {
196 			kfree_skb_list(segs);
197 			return ERR_PTR(err);
198 		}
199 
200 		if (!skb_is_gso(skb2))
201 			seq++;
202 		else
203 			seq += skb_shinfo(skb2)->gso_segs;
204 
205 		skb_push(skb2, skb2->mac_len);
206 		skb2 = nskb;
207 	} while (skb2);
208 
209 out:
210 	return segs;
211 }
212 
213 static int esp6_input_tail(struct xfrm_state *x, struct sk_buff *skb)
214 {
215 	struct crypto_aead *aead = x->data;
216 	struct xfrm_offload *xo = xfrm_offload(skb);
217 
218 	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
219 		return -EINVAL;
220 
221 	if (!(xo->flags & CRYPTO_DONE))
222 		skb->ip_summed = CHECKSUM_NONE;
223 
224 	return esp6_input_done2(skb, 0);
225 }
226 
227 static int esp6_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_t features)
228 {
229 	int err;
230 	int alen;
231 	int blksize;
232 	struct xfrm_offload *xo;
233 	struct ip_esp_hdr *esph;
234 	struct crypto_aead *aead;
235 	struct esp_info esp;
236 	bool hw_offload = true;
237 
238 	esp.inplace = true;
239 
240 	xo = xfrm_offload(skb);
241 
242 	if (!xo)
243 		return -EINVAL;
244 
245 	if (!(features & NETIF_F_HW_ESP) || !x->xso.offload_handle ||
246 	    (x->xso.dev != skb->dev)) {
247 		xo->flags |= CRYPTO_FALLBACK;
248 		hw_offload = false;
249 	}
250 
251 	esp.proto = xo->proto;
252 
253 	/* skb is pure payload to encrypt */
254 
255 	aead = x->data;
256 	alen = crypto_aead_authsize(aead);
257 
258 	esp.tfclen = 0;
259 	/* XXX: Add support for tfc padding here. */
260 
261 	blksize = ALIGN(crypto_aead_blocksize(aead), 4);
262 	esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
263 	esp.plen = esp.clen - skb->len - esp.tfclen;
264 	esp.tailen = esp.tfclen + esp.plen + alen;
265 
266 	if (!hw_offload || (hw_offload && !skb_is_gso(skb))) {
267 		esp.nfrags = esp6_output_head(x, skb, &esp);
268 		if (esp.nfrags < 0)
269 			return esp.nfrags;
270 	}
271 
272 	esph = ip_esp_hdr(skb);
273 	esph->spi = x->id.spi;
274 
275 	skb_push(skb, -skb_network_offset(skb));
276 
277 	if (xo->flags & XFRM_GSO_SEGMENT) {
278 		esph->seq_no = htonl(xo->seq.low);
279 	} else {
280 		int len;
281 
282 		len = skb->len - sizeof(struct ipv6hdr);
283 		if (len > IPV6_MAXPLEN)
284 			len = 0;
285 
286 		ipv6_hdr(skb)->payload_len = htons(len);
287 	}
288 
289 	if (hw_offload)
290 		return 0;
291 
292 	esp.seqno = cpu_to_be64(xo->seq.low + ((u64)xo->seq.hi << 32));
293 
294 	err = esp6_output_tail(x, skb, &esp);
295 	if (err)
296 		return err;
297 
298 	secpath_reset(skb);
299 
300 	return 0;
301 }
302 
303 static const struct net_offload esp6_offload = {
304 	.callbacks = {
305 		.gro_receive = esp6_gro_receive,
306 		.gso_segment = esp6_gso_segment,
307 	},
308 };
309 
310 static const struct xfrm_type_offload esp6_type_offload = {
311 	.description	= "ESP6 OFFLOAD",
312 	.owner		= THIS_MODULE,
313 	.proto	     	= IPPROTO_ESP,
314 	.input_tail	= esp6_input_tail,
315 	.xmit		= esp6_xmit,
316 	.encap		= esp6_gso_encap,
317 };
318 
319 static int __init esp6_offload_init(void)
320 {
321 	if (xfrm_register_type_offload(&esp6_type_offload, AF_INET6) < 0) {
322 		pr_info("%s: can't add xfrm type offload\n", __func__);
323 		return -EAGAIN;
324 	}
325 
326 	return inet6_add_offload(&esp6_offload, IPPROTO_ESP);
327 }
328 
329 static void __exit esp6_offload_exit(void)
330 {
331 	if (xfrm_unregister_type_offload(&esp6_type_offload, AF_INET6) < 0)
332 		pr_info("%s: can't remove xfrm type offload\n", __func__);
333 
334 	inet6_del_offload(&esp6_offload, IPPROTO_ESP);
335 }
336 
337 module_init(esp6_offload_init);
338 module_exit(esp6_offload_exit);
339 MODULE_LICENSE("GPL");
340 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
341 MODULE_ALIAS_XFRM_OFFLOAD_TYPE(AF_INET6, XFRM_PROTO_ESP);
342