xref: /openbmc/linux/net/ipv6/esp6_offload.c (revision 4cff79e9)
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 	struct xfrm_state *x;
140 	struct ip_esp_hdr *esph;
141 	struct crypto_aead *aead;
142 	netdev_features_t esp_features = features;
143 	struct xfrm_offload *xo = xfrm_offload(skb);
144 
145 	if (!xo)
146 		return ERR_PTR(-EINVAL);
147 
148 	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_ESP))
149 		return ERR_PTR(-EINVAL);
150 
151 	x = skb->sp->xvec[skb->sp->len - 1];
152 	aead = x->data;
153 	esph = ip_esp_hdr(skb);
154 
155 	if (esph->spi != x->id.spi)
156 		return ERR_PTR(-EINVAL);
157 
158 	if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
159 		return ERR_PTR(-EINVAL);
160 
161 	__skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
162 
163 	skb->encap_hdr_csum = 1;
164 
165 	if (!(features & NETIF_F_HW_ESP) || !x->xso.offload_handle ||
166 	    (x->xso.dev != skb->dev))
167 		esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK);
168 	else if (!(features & NETIF_F_HW_ESP_TX_CSUM))
169 		esp_features = features & ~NETIF_F_CSUM_MASK;
170 
171 	xo->flags |= XFRM_GSO_SEGMENT;
172 
173 	return x->outer_mode->gso_segment(x, skb, esp_features);
174 }
175 
176 static int esp6_input_tail(struct xfrm_state *x, struct sk_buff *skb)
177 {
178 	struct crypto_aead *aead = x->data;
179 	struct xfrm_offload *xo = xfrm_offload(skb);
180 
181 	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
182 		return -EINVAL;
183 
184 	if (!(xo->flags & CRYPTO_DONE))
185 		skb->ip_summed = CHECKSUM_NONE;
186 
187 	return esp6_input_done2(skb, 0);
188 }
189 
190 static int esp6_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_t features)
191 {
192 	int len;
193 	int err;
194 	int alen;
195 	int blksize;
196 	struct xfrm_offload *xo;
197 	struct ip_esp_hdr *esph;
198 	struct crypto_aead *aead;
199 	struct esp_info esp;
200 	bool hw_offload = true;
201 	__u32 seq;
202 
203 	esp.inplace = true;
204 
205 	xo = xfrm_offload(skb);
206 
207 	if (!xo)
208 		return -EINVAL;
209 
210 	if (!(features & NETIF_F_HW_ESP) || !x->xso.offload_handle ||
211 	    (x->xso.dev != skb->dev)) {
212 		xo->flags |= CRYPTO_FALLBACK;
213 		hw_offload = false;
214 	}
215 
216 	esp.proto = xo->proto;
217 
218 	/* skb is pure payload to encrypt */
219 
220 	aead = x->data;
221 	alen = crypto_aead_authsize(aead);
222 
223 	esp.tfclen = 0;
224 	/* XXX: Add support for tfc padding here. */
225 
226 	blksize = ALIGN(crypto_aead_blocksize(aead), 4);
227 	esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
228 	esp.plen = esp.clen - skb->len - esp.tfclen;
229 	esp.tailen = esp.tfclen + esp.plen + alen;
230 
231 	if (!hw_offload || (hw_offload && !skb_is_gso(skb))) {
232 		esp.nfrags = esp6_output_head(x, skb, &esp);
233 		if (esp.nfrags < 0)
234 			return esp.nfrags;
235 	}
236 
237 	seq = xo->seq.low;
238 
239 	esph = ip_esp_hdr(skb);
240 	esph->spi = x->id.spi;
241 
242 	skb_push(skb, -skb_network_offset(skb));
243 
244 	if (xo->flags & XFRM_GSO_SEGMENT) {
245 		esph->seq_no = htonl(seq);
246 
247 		if (!skb_is_gso(skb))
248 			xo->seq.low++;
249 		else
250 			xo->seq.low += skb_shinfo(skb)->gso_segs;
251 	}
252 
253 	esp.seqno = cpu_to_be64(xo->seq.low + ((u64)xo->seq.hi << 32));
254 
255 	len = skb->len - sizeof(struct ipv6hdr);
256 	if (len > IPV6_MAXPLEN)
257 		len = 0;
258 
259 	ipv6_hdr(skb)->payload_len = htons(len);
260 
261 	if (hw_offload)
262 		return 0;
263 
264 	err = esp6_output_tail(x, skb, &esp);
265 	if (err)
266 		return err;
267 
268 	secpath_reset(skb);
269 
270 	return 0;
271 }
272 
273 static const struct net_offload esp6_offload = {
274 	.callbacks = {
275 		.gro_receive = esp6_gro_receive,
276 		.gso_segment = esp6_gso_segment,
277 	},
278 };
279 
280 static const struct xfrm_type_offload esp6_type_offload = {
281 	.description	= "ESP6 OFFLOAD",
282 	.owner		= THIS_MODULE,
283 	.proto	     	= IPPROTO_ESP,
284 	.input_tail	= esp6_input_tail,
285 	.xmit		= esp6_xmit,
286 	.encap		= esp6_gso_encap,
287 };
288 
289 static int __init esp6_offload_init(void)
290 {
291 	if (xfrm_register_type_offload(&esp6_type_offload, AF_INET6) < 0) {
292 		pr_info("%s: can't add xfrm type offload\n", __func__);
293 		return -EAGAIN;
294 	}
295 
296 	return inet6_add_offload(&esp6_offload, IPPROTO_ESP);
297 }
298 
299 static void __exit esp6_offload_exit(void)
300 {
301 	if (xfrm_unregister_type_offload(&esp6_type_offload, AF_INET6) < 0)
302 		pr_info("%s: can't remove xfrm type offload\n", __func__);
303 
304 	inet6_del_offload(&esp6_offload, IPPROTO_ESP);
305 }
306 
307 module_init(esp6_offload_init);
308 module_exit(esp6_offload_exit);
309 MODULE_LICENSE("GPL");
310 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
311 MODULE_ALIAS_XFRM_OFFLOAD_TYPE(AF_INET6, XFRM_PROTO_ESP);
312