xref: /openbmc/linux/net/ipv6/esp6_offload.c (revision 239480ab) 
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 struct sk_buff **esp6_gro_receive(struct sk_buff **head,
34 					 struct sk_buff *skb)
35 {
36 	int offset = skb_gro_offset(skb);
37 	struct xfrm_offload *xo;
38 	struct xfrm_state *x;
39 	__be32 seq;
40 	__be32 spi;
41 	int err;
42 
43 	skb_pull(skb, offset);
44 
45 	if ((err = xfrm_parse_spi(skb, IPPROTO_ESP, &spi, &seq)) != 0)
46 		goto out;
47 
48 	xo = xfrm_offload(skb);
49 	if (!xo || !(xo->flags & CRYPTO_DONE)) {
50 		err = secpath_set(skb);
51 		if (err)
52 			goto out;
53 
54 		if (skb->sp->len == XFRM_MAX_DEPTH)
55 			goto out;
56 
57 		x = xfrm_state_lookup(dev_net(skb->dev), skb->mark,
58 				      (xfrm_address_t *)&ipv6_hdr(skb)->daddr,
59 				      spi, IPPROTO_ESP, AF_INET6);
60 		if (!x)
61 			goto out;
62 
63 		skb->sp->xvec[skb->sp->len++] = x;
64 		skb->sp->olen++;
65 
66 		xo = xfrm_offload(skb);
67 		if (!xo) {
68 			xfrm_state_put(x);
69 			goto out;
70 		}
71 	}
72 
73 	xo->flags |= XFRM_GRO;
74 
75 	XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6 = NULL;
76 	XFRM_SPI_SKB_CB(skb)->family = AF_INET6;
77 	XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct ipv6hdr, daddr);
78 	XFRM_SPI_SKB_CB(skb)->seq = seq;
79 
80 	/* We don't need to handle errors from xfrm_input, it does all
81 	 * the error handling and frees the resources on error. */
82 	xfrm_input(skb, IPPROTO_ESP, spi, -2);
83 
84 	return ERR_PTR(-EINPROGRESS);
85 out:
86 	skb_push(skb, offset);
87 	NAPI_GRO_CB(skb)->same_flow = 0;
88 	NAPI_GRO_CB(skb)->flush = 1;
89 
90 	return NULL;
91 }
92 
93 static void esp6_gso_encap(struct xfrm_state *x, struct sk_buff *skb)
94 {
95 	struct ip_esp_hdr *esph;
96 	struct ipv6hdr *iph = ipv6_hdr(skb);
97 	struct xfrm_offload *xo = xfrm_offload(skb);
98 	int proto = iph->nexthdr;
99 
100 	skb_push(skb, -skb_network_offset(skb));
101 	esph = ip_esp_hdr(skb);
102 	*skb_mac_header(skb) = IPPROTO_ESP;
103 
104 	esph->spi = x->id.spi;
105 	esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
106 
107 	xo->proto = proto;
108 }
109 
110 static struct sk_buff *esp6_gso_segment(struct sk_buff *skb,
111 				        netdev_features_t features)
112 {
113 	__u32 seq;
114 	int err = 0;
115 	struct sk_buff *skb2;
116 	struct xfrm_state *x;
117 	struct ip_esp_hdr *esph;
118 	struct crypto_aead *aead;
119 	struct sk_buff *segs = ERR_PTR(-EINVAL);
120 	netdev_features_t esp_features = features;
121 	struct xfrm_offload *xo = xfrm_offload(skb);
122 
123 	if (!xo)
124 		goto out;
125 
126 	seq = xo->seq.low;
127 
128 	x = skb->sp->xvec[skb->sp->len - 1];
129 	aead = x->data;
130 	esph = ip_esp_hdr(skb);
131 
132 	if (esph->spi != x->id.spi)
133 		goto out;
134 
135 	if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
136 		goto out;
137 
138 	__skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
139 
140 	skb->encap_hdr_csum = 1;
141 
142 	if (!(features & NETIF_F_HW_ESP))
143 		esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK);
144 
145 	segs = x->outer_mode->gso_segment(x, skb, esp_features);
146 	if (IS_ERR_OR_NULL(segs))
147 		goto out;
148 
149 	__skb_pull(skb, skb->data - skb_mac_header(skb));
150 
151 	skb2 = segs;
152 	do {
153 		struct sk_buff *nskb = skb2->next;
154 
155 		xo = xfrm_offload(skb2);
156 		xo->flags |= XFRM_GSO_SEGMENT;
157 		xo->seq.low = seq;
158 		xo->seq.hi = xfrm_replay_seqhi(x, seq);
159 
160 		if(!(features & NETIF_F_HW_ESP))
161 			xo->flags |= CRYPTO_FALLBACK;
162 
163 		x->outer_mode->xmit(x, skb2);
164 
165 		err = x->type_offload->xmit(x, skb2, esp_features);
166 		if (err) {
167 			kfree_skb_list(segs);
168 			return ERR_PTR(err);
169 		}
170 
171 		if (!skb_is_gso(skb2))
172 			seq++;
173 		else
174 			seq += skb_shinfo(skb2)->gso_segs;
175 
176 		skb_push(skb2, skb2->mac_len);
177 		skb2 = nskb;
178 	} while (skb2);
179 
180 out:
181 	return segs;
182 }
183 
184 static int esp6_input_tail(struct xfrm_state *x, struct sk_buff *skb)
185 {
186 	struct crypto_aead *aead = x->data;
187 
188 	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
189 		return -EINVAL;
190 
191 	skb->ip_summed = CHECKSUM_NONE;
192 
193 	return esp6_input_done2(skb, 0);
194 }
195 
196 static int esp6_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_t features)
197 {
198 	int err;
199 	int alen;
200 	int blksize;
201 	struct xfrm_offload *xo;
202 	struct ip_esp_hdr *esph;
203 	struct crypto_aead *aead;
204 	struct esp_info esp;
205 	bool hw_offload = true;
206 
207 	esp.inplace = true;
208 
209 	xo = xfrm_offload(skb);
210 
211 	if (!xo)
212 		return -EINVAL;
213 
214 	if (!(features & NETIF_F_HW_ESP) || !x->xso.offload_handle ||
215 	    (x->xso.dev != skb->dev)) {
216 		xo->flags |= CRYPTO_FALLBACK;
217 		hw_offload = false;
218 	}
219 
220 	esp.proto = xo->proto;
221 
222 	/* skb is pure payload to encrypt */
223 
224 	aead = x->data;
225 	alen = crypto_aead_authsize(aead);
226 
227 	esp.tfclen = 0;
228 	/* XXX: Add support for tfc padding here. */
229 
230 	blksize = ALIGN(crypto_aead_blocksize(aead), 4);
231 	esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
232 	esp.plen = esp.clen - skb->len - esp.tfclen;
233 	esp.tailen = esp.tfclen + esp.plen + alen;
234 
235 	if (!hw_offload || (hw_offload && !skb_is_gso(skb))) {
236 		esp.nfrags = esp6_output_head(x, skb, &esp);
237 		if (esp.nfrags < 0)
238 			return esp.nfrags;
239 	}
240 
241 	esph = ip_esp_hdr(skb);
242 	esph->spi = x->id.spi;
243 
244 	skb_push(skb, -skb_network_offset(skb));
245 
246 	if (xo->flags & XFRM_GSO_SEGMENT) {
247 		esph->seq_no = htonl(xo->seq.low);
248 	} else {
249 		int len;
250 
251 		len = skb->len - sizeof(struct ipv6hdr);
252 		if (len > IPV6_MAXPLEN)
253 			len = 0;
254 
255 		ipv6_hdr(skb)->payload_len = htons(len);
256 	}
257 
258 	if (hw_offload)
259 		return 0;
260 
261 	esp.seqno = cpu_to_be64(xo->seq.low + ((u64)xo->seq.hi << 32));
262 
263 	err = esp6_output_tail(x, skb, &esp);
264 	if (err < 0)
265 		return err;
266 
267 	secpath_reset(skb);
268 
269 	return 0;
270 }
271 
272 static const struct net_offload esp6_offload = {
273 	.callbacks = {
274 		.gro_receive = esp6_gro_receive,
275 		.gso_segment = esp6_gso_segment,
276 	},
277 };
278 
279 static const struct xfrm_type_offload esp6_type_offload = {
280 	.description	= "ESP6 OFFLOAD",
281 	.owner		= THIS_MODULE,
282 	.proto	     	= IPPROTO_ESP,
283 	.input_tail	= esp6_input_tail,
284 	.xmit		= esp6_xmit,
285 	.encap		= esp6_gso_encap,
286 };
287 
288 static int __init esp6_offload_init(void)
289 {
290 	if (xfrm_register_type_offload(&esp6_type_offload, AF_INET6) < 0) {
291 		pr_info("%s: can't add xfrm type offload\n", __func__);
292 		return -EAGAIN;
293 	}
294 
295 	return inet6_add_offload(&esp6_offload, IPPROTO_ESP);
296 }
297 
298 static void __exit esp6_offload_exit(void)
299 {
300 	if (xfrm_unregister_type_offload(&esp6_type_offload, AF_INET6) < 0)
301 		pr_info("%s: can't remove xfrm type offload\n", __func__);
302 
303 	inet6_del_offload(&esp6_offload, IPPROTO_ESP);
304 }
305 
306 module_init(esp6_offload_init);
307 module_exit(esp6_offload_exit);
308 MODULE_LICENSE("GPL");
309 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
310