xref: /openbmc/linux/net/ipv6/esp6_offload.c (revision 2874c5fd) 
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 list_head *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 		struct sec_path *sp = secpath_set(skb);
72 
73 		if (!sp)
74 			goto out;
75 
76 		if (sp->len == XFRM_MAX_DEPTH)
77 			goto out_reset;
78 
79 		x = xfrm_state_lookup(dev_net(skb->dev), skb->mark,
80 				      (xfrm_address_t *)&ipv6_hdr(skb)->daddr,
81 				      spi, IPPROTO_ESP, AF_INET6);
82 		if (!x)
83 			goto out_reset;
84 
85 		sp->xvec[sp->len++] = x;
86 		sp->olen++;
87 
88 		xo = xfrm_offload(skb);
89 		if (!xo) {
90 			xfrm_state_put(x);
91 			goto out_reset;
92 		}
93 	}
94 
95 	xo->flags |= XFRM_GRO;
96 
97 	nhoff = esp6_nexthdr_esp_offset(ipv6_hdr(skb), offset);
98 	if (!nhoff)
99 		goto out;
100 
101 	IP6CB(skb)->nhoff = nhoff;
102 	XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6 = NULL;
103 	XFRM_SPI_SKB_CB(skb)->family = AF_INET6;
104 	XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct ipv6hdr, daddr);
105 	XFRM_SPI_SKB_CB(skb)->seq = seq;
106 
107 	/* We don't need to handle errors from xfrm_input, it does all
108 	 * the error handling and frees the resources on error. */
109 	xfrm_input(skb, IPPROTO_ESP, spi, -2);
110 
111 	return ERR_PTR(-EINPROGRESS);
112 out_reset:
113 	secpath_reset(skb);
114 out:
115 	skb_push(skb, offset);
116 	NAPI_GRO_CB(skb)->same_flow = 0;
117 	NAPI_GRO_CB(skb)->flush = 1;
118 
119 	return NULL;
120 }
121 
122 static void esp6_gso_encap(struct xfrm_state *x, struct sk_buff *skb)
123 {
124 	struct ip_esp_hdr *esph;
125 	struct ipv6hdr *iph = ipv6_hdr(skb);
126 	struct xfrm_offload *xo = xfrm_offload(skb);
127 	int proto = iph->nexthdr;
128 
129 	skb_push(skb, -skb_network_offset(skb));
130 	esph = ip_esp_hdr(skb);
131 	*skb_mac_header(skb) = IPPROTO_ESP;
132 
133 	esph->spi = x->id.spi;
134 	esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
135 
136 	xo->proto = proto;
137 }
138 
139 static struct sk_buff *xfrm6_tunnel_gso_segment(struct xfrm_state *x,
140 						struct sk_buff *skb,
141 						netdev_features_t features)
142 {
143 	__skb_push(skb, skb->mac_len);
144 	return skb_mac_gso_segment(skb, features);
145 }
146 
147 static struct sk_buff *xfrm6_transport_gso_segment(struct xfrm_state *x,
148 						   struct sk_buff *skb,
149 						   netdev_features_t features)
150 {
151 	const struct net_offload *ops;
152 	struct sk_buff *segs = ERR_PTR(-EINVAL);
153 	struct xfrm_offload *xo = xfrm_offload(skb);
154 
155 	skb->transport_header += x->props.header_len;
156 	ops = rcu_dereference(inet6_offloads[xo->proto]);
157 	if (likely(ops && ops->callbacks.gso_segment))
158 		segs = ops->callbacks.gso_segment(skb, features);
159 
160 	return segs;
161 }
162 
163 static struct sk_buff *xfrm6_outer_mode_gso_segment(struct xfrm_state *x,
164 						    struct sk_buff *skb,
165 						    netdev_features_t features)
166 {
167 	switch (x->outer_mode.encap) {
168 	case XFRM_MODE_TUNNEL:
169 		return xfrm6_tunnel_gso_segment(x, skb, features);
170 	case XFRM_MODE_TRANSPORT:
171 		return xfrm6_transport_gso_segment(x, skb, features);
172 	}
173 
174 	return ERR_PTR(-EOPNOTSUPP);
175 }
176 
177 static struct sk_buff *esp6_gso_segment(struct sk_buff *skb,
178 				        netdev_features_t features)
179 {
180 	struct xfrm_state *x;
181 	struct ip_esp_hdr *esph;
182 	struct crypto_aead *aead;
183 	netdev_features_t esp_features = features;
184 	struct xfrm_offload *xo = xfrm_offload(skb);
185 	struct sec_path *sp;
186 
187 	if (!xo)
188 		return ERR_PTR(-EINVAL);
189 
190 	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_ESP))
191 		return ERR_PTR(-EINVAL);
192 
193 	sp = skb_sec_path(skb);
194 	x = sp->xvec[sp->len - 1];
195 	aead = x->data;
196 	esph = ip_esp_hdr(skb);
197 
198 	if (esph->spi != x->id.spi)
199 		return ERR_PTR(-EINVAL);
200 
201 	if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
202 		return ERR_PTR(-EINVAL);
203 
204 	__skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
205 
206 	skb->encap_hdr_csum = 1;
207 
208 	if (!(features & NETIF_F_HW_ESP) || x->xso.dev != skb->dev)
209 		esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK);
210 	else if (!(features & NETIF_F_HW_ESP_TX_CSUM))
211 		esp_features = features & ~NETIF_F_CSUM_MASK;
212 
213 	xo->flags |= XFRM_GSO_SEGMENT;
214 
215 	return xfrm6_outer_mode_gso_segment(x, skb, esp_features);
216 }
217 
218 static int esp6_input_tail(struct xfrm_state *x, struct sk_buff *skb)
219 {
220 	struct crypto_aead *aead = x->data;
221 	struct xfrm_offload *xo = xfrm_offload(skb);
222 
223 	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
224 		return -EINVAL;
225 
226 	if (!(xo->flags & CRYPTO_DONE))
227 		skb->ip_summed = CHECKSUM_NONE;
228 
229 	return esp6_input_done2(skb, 0);
230 }
231 
232 static int esp6_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_t features)
233 {
234 	int len;
235 	int err;
236 	int alen;
237 	int blksize;
238 	struct xfrm_offload *xo;
239 	struct ip_esp_hdr *esph;
240 	struct crypto_aead *aead;
241 	struct esp_info esp;
242 	bool hw_offload = true;
243 	__u32 seq;
244 
245 	esp.inplace = true;
246 
247 	xo = xfrm_offload(skb);
248 
249 	if (!xo)
250 		return -EINVAL;
251 
252 	if (!(features & NETIF_F_HW_ESP) || x->xso.dev != skb->dev) {
253 		xo->flags |= CRYPTO_FALLBACK;
254 		hw_offload = false;
255 	}
256 
257 	esp.proto = xo->proto;
258 
259 	/* skb is pure payload to encrypt */
260 
261 	aead = x->data;
262 	alen = crypto_aead_authsize(aead);
263 
264 	esp.tfclen = 0;
265 	/* XXX: Add support for tfc padding here. */
266 
267 	blksize = ALIGN(crypto_aead_blocksize(aead), 4);
268 	esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
269 	esp.plen = esp.clen - skb->len - esp.tfclen;
270 	esp.tailen = esp.tfclen + esp.plen + alen;
271 
272 	if (!hw_offload || (hw_offload && !skb_is_gso(skb))) {
273 		esp.nfrags = esp6_output_head(x, skb, &esp);
274 		if (esp.nfrags < 0)
275 			return esp.nfrags;
276 	}
277 
278 	seq = xo->seq.low;
279 
280 	esph = ip_esp_hdr(skb);
281 	esph->spi = x->id.spi;
282 
283 	skb_push(skb, -skb_network_offset(skb));
284 
285 	if (xo->flags & XFRM_GSO_SEGMENT) {
286 		esph->seq_no = htonl(seq);
287 
288 		if (!skb_is_gso(skb))
289 			xo->seq.low++;
290 		else
291 			xo->seq.low += skb_shinfo(skb)->gso_segs;
292 	}
293 
294 	esp.seqno = cpu_to_be64(xo->seq.low + ((u64)xo->seq.hi << 32));
295 
296 	len = skb->len - sizeof(struct ipv6hdr);
297 	if (len > IPV6_MAXPLEN)
298 		len = 0;
299 
300 	ipv6_hdr(skb)->payload_len = htons(len);
301 
302 	if (hw_offload)
303 		return 0;
304 
305 	err = esp6_output_tail(x, skb, &esp);
306 	if (err)
307 		return err;
308 
309 	secpath_reset(skb);
310 
311 	return 0;
312 }
313 
314 static const struct net_offload esp6_offload = {
315 	.callbacks = {
316 		.gro_receive = esp6_gro_receive,
317 		.gso_segment = esp6_gso_segment,
318 	},
319 };
320 
321 static const struct xfrm_type_offload esp6_type_offload = {
322 	.description	= "ESP6 OFFLOAD",
323 	.owner		= THIS_MODULE,
324 	.proto	     	= IPPROTO_ESP,
325 	.input_tail	= esp6_input_tail,
326 	.xmit		= esp6_xmit,
327 	.encap		= esp6_gso_encap,
328 };
329 
330 static int __init esp6_offload_init(void)
331 {
332 	if (xfrm_register_type_offload(&esp6_type_offload, AF_INET6) < 0) {
333 		pr_info("%s: can't add xfrm type offload\n", __func__);
334 		return -EAGAIN;
335 	}
336 
337 	return inet6_add_offload(&esp6_offload, IPPROTO_ESP);
338 }
339 
340 static void __exit esp6_offload_exit(void)
341 {
342 	if (xfrm_unregister_type_offload(&esp6_type_offload, AF_INET6) < 0)
343 		pr_info("%s: can't remove xfrm type offload\n", __func__);
344 
345 	inet6_del_offload(&esp6_offload, IPPROTO_ESP);
346 }
347 
348 module_init(esp6_offload_init);
349 module_exit(esp6_offload_exit);
350 MODULE_LICENSE("GPL");
351 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
352 MODULE_ALIAS_XFRM_OFFLOAD_TYPE(AF_INET6, XFRM_PROTO_ESP);
353