xref: /openbmc/linux/net/ipv6/esp6_offload.c (revision c8dbaa22) 
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 	skb_pull(skb, offset);
64 
65 	if ((err = xfrm_parse_spi(skb, IPPROTO_ESP, &spi, &seq)) != 0)
66 		goto out;
67 
68 	xo = xfrm_offload(skb);
69 	if (!xo || !(xo->flags & CRYPTO_DONE)) {
70 		err = secpath_set(skb);
71 		if (err)
72 			goto out;
73 
74 		if (skb->sp->len == XFRM_MAX_DEPTH)
75 			goto out;
76 
77 		x = xfrm_state_lookup(dev_net(skb->dev), skb->mark,
78 				      (xfrm_address_t *)&ipv6_hdr(skb)->daddr,
79 				      spi, IPPROTO_ESP, AF_INET6);
80 		if (!x)
81 			goto out;
82 
83 		skb->sp->xvec[skb->sp->len++] = x;
84 		skb->sp->olen++;
85 
86 		xo = xfrm_offload(skb);
87 		if (!xo) {
88 			xfrm_state_put(x);
89 			goto out;
90 		}
91 	}
92 
93 	xo->flags |= XFRM_GRO;
94 
95 	nhoff = esp6_nexthdr_esp_offset(ipv6_hdr(skb), offset);
96 	if (!nhoff)
97 		goto out;
98 
99 	IP6CB(skb)->nhoff = nhoff;
100 	XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6 = NULL;
101 	XFRM_SPI_SKB_CB(skb)->family = AF_INET6;
102 	XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct ipv6hdr, daddr);
103 	XFRM_SPI_SKB_CB(skb)->seq = seq;
104 
105 	/* We don't need to handle errors from xfrm_input, it does all
106 	 * the error handling and frees the resources on error. */
107 	xfrm_input(skb, IPPROTO_ESP, spi, -2);
108 
109 	return ERR_PTR(-EINPROGRESS);
110 out:
111 	skb_push(skb, offset);
112 	NAPI_GRO_CB(skb)->same_flow = 0;
113 	NAPI_GRO_CB(skb)->flush = 1;
114 
115 	return NULL;
116 }
117 
118 static void esp6_gso_encap(struct xfrm_state *x, struct sk_buff *skb)
119 {
120 	struct ip_esp_hdr *esph;
121 	struct ipv6hdr *iph = ipv6_hdr(skb);
122 	struct xfrm_offload *xo = xfrm_offload(skb);
123 	int proto = iph->nexthdr;
124 
125 	skb_push(skb, -skb_network_offset(skb));
126 	esph = ip_esp_hdr(skb);
127 	*skb_mac_header(skb) = IPPROTO_ESP;
128 
129 	esph->spi = x->id.spi;
130 	esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
131 
132 	xo->proto = proto;
133 }
134 
135 static struct sk_buff *esp6_gso_segment(struct sk_buff *skb,
136 				        netdev_features_t features)
137 {
138 	__u32 seq;
139 	int err = 0;
140 	struct sk_buff *skb2;
141 	struct xfrm_state *x;
142 	struct ip_esp_hdr *esph;
143 	struct crypto_aead *aead;
144 	struct sk_buff *segs = ERR_PTR(-EINVAL);
145 	netdev_features_t esp_features = features;
146 	struct xfrm_offload *xo = xfrm_offload(skb);
147 
148 	if (!xo)
149 		goto out;
150 
151 	seq = xo->seq.low;
152 
153 	x = skb->sp->xvec[skb->sp->len - 1];
154 	aead = x->data;
155 	esph = ip_esp_hdr(skb);
156 
157 	if (esph->spi != x->id.spi)
158 		goto out;
159 
160 	if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
161 		goto out;
162 
163 	__skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
164 
165 	skb->encap_hdr_csum = 1;
166 
167 	if (!(features & NETIF_F_HW_ESP))
168 		esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK);
169 
170 	segs = x->outer_mode->gso_segment(x, skb, esp_features);
171 	if (IS_ERR_OR_NULL(segs))
172 		goto out;
173 
174 	__skb_pull(skb, skb->data - skb_mac_header(skb));
175 
176 	skb2 = segs;
177 	do {
178 		struct sk_buff *nskb = skb2->next;
179 
180 		xo = xfrm_offload(skb2);
181 		xo->flags |= XFRM_GSO_SEGMENT;
182 		xo->seq.low = seq;
183 		xo->seq.hi = xfrm_replay_seqhi(x, seq);
184 
185 		if(!(features & NETIF_F_HW_ESP))
186 			xo->flags |= CRYPTO_FALLBACK;
187 
188 		x->outer_mode->xmit(x, skb2);
189 
190 		err = x->type_offload->xmit(x, skb2, esp_features);
191 		if (err) {
192 			kfree_skb_list(segs);
193 			return ERR_PTR(err);
194 		}
195 
196 		if (!skb_is_gso(skb2))
197 			seq++;
198 		else
199 			seq += skb_shinfo(skb2)->gso_segs;
200 
201 		skb_push(skb2, skb2->mac_len);
202 		skb2 = nskb;
203 	} while (skb2);
204 
205 out:
206 	return segs;
207 }
208 
209 static int esp6_input_tail(struct xfrm_state *x, struct sk_buff *skb)
210 {
211 	struct crypto_aead *aead = x->data;
212 
213 	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
214 		return -EINVAL;
215 
216 	skb->ip_summed = CHECKSUM_NONE;
217 
218 	return esp6_input_done2(skb, 0);
219 }
220 
221 static int esp6_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_t features)
222 {
223 	int err;
224 	int alen;
225 	int blksize;
226 	struct xfrm_offload *xo;
227 	struct ip_esp_hdr *esph;
228 	struct crypto_aead *aead;
229 	struct esp_info esp;
230 	bool hw_offload = true;
231 
232 	esp.inplace = true;
233 
234 	xo = xfrm_offload(skb);
235 
236 	if (!xo)
237 		return -EINVAL;
238 
239 	if (!(features & NETIF_F_HW_ESP) || !x->xso.offload_handle ||
240 	    (x->xso.dev != skb->dev)) {
241 		xo->flags |= CRYPTO_FALLBACK;
242 		hw_offload = false;
243 	}
244 
245 	esp.proto = xo->proto;
246 
247 	/* skb is pure payload to encrypt */
248 
249 	aead = x->data;
250 	alen = crypto_aead_authsize(aead);
251 
252 	esp.tfclen = 0;
253 	/* XXX: Add support for tfc padding here. */
254 
255 	blksize = ALIGN(crypto_aead_blocksize(aead), 4);
256 	esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
257 	esp.plen = esp.clen - skb->len - esp.tfclen;
258 	esp.tailen = esp.tfclen + esp.plen + alen;
259 
260 	if (!hw_offload || (hw_offload && !skb_is_gso(skb))) {
261 		esp.nfrags = esp6_output_head(x, skb, &esp);
262 		if (esp.nfrags < 0)
263 			return esp.nfrags;
264 	}
265 
266 	esph = ip_esp_hdr(skb);
267 	esph->spi = x->id.spi;
268 
269 	skb_push(skb, -skb_network_offset(skb));
270 
271 	if (xo->flags & XFRM_GSO_SEGMENT) {
272 		esph->seq_no = htonl(xo->seq.low);
273 	} else {
274 		int len;
275 
276 		len = skb->len - sizeof(struct ipv6hdr);
277 		if (len > IPV6_MAXPLEN)
278 			len = 0;
279 
280 		ipv6_hdr(skb)->payload_len = htons(len);
281 	}
282 
283 	if (hw_offload)
284 		return 0;
285 
286 	esp.seqno = cpu_to_be64(xo->seq.low + ((u64)xo->seq.hi << 32));
287 
288 	err = esp6_output_tail(x, skb, &esp);
289 	if (err < 0)
290 		return err;
291 
292 	secpath_reset(skb);
293 
294 	return 0;
295 }
296 
297 static const struct net_offload esp6_offload = {
298 	.callbacks = {
299 		.gro_receive = esp6_gro_receive,
300 		.gso_segment = esp6_gso_segment,
301 	},
302 };
303 
304 static const struct xfrm_type_offload esp6_type_offload = {
305 	.description	= "ESP6 OFFLOAD",
306 	.owner		= THIS_MODULE,
307 	.proto	     	= IPPROTO_ESP,
308 	.input_tail	= esp6_input_tail,
309 	.xmit		= esp6_xmit,
310 	.encap		= esp6_gso_encap,
311 };
312 
313 static int __init esp6_offload_init(void)
314 {
315 	if (xfrm_register_type_offload(&esp6_type_offload, AF_INET6) < 0) {
316 		pr_info("%s: can't add xfrm type offload\n", __func__);
317 		return -EAGAIN;
318 	}
319 
320 	return inet6_add_offload(&esp6_offload, IPPROTO_ESP);
321 }
322 
323 static void __exit esp6_offload_exit(void)
324 {
325 	if (xfrm_unregister_type_offload(&esp6_type_offload, AF_INET6) < 0)
326 		pr_info("%s: can't remove xfrm type offload\n", __func__);
327 
328 	inet6_del_offload(&esp6_offload, IPPROTO_ESP);
329 }
330 
331 module_init(esp6_offload_init);
332 module_exit(esp6_offload_exit);
333 MODULE_LICENSE("GPL");
334 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
335