xref: /openbmc/linux/net/ipv6/esp6_offload.c (revision ecd25094) 
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * IPV6 GSO/GRO offload support
4  * Linux INET implementation
5  *
6  * Copyright (C) 2016 secunet Security Networks AG
7  * Author: Steffen Klassert <steffen.klassert@secunet.com>
8  *
9  * ESP GRO support
10  */
11 
12 #include <linux/skbuff.h>
13 #include <linux/init.h>
14 #include <net/protocol.h>
15 #include <crypto/aead.h>
16 #include <crypto/authenc.h>
17 #include <linux/err.h>
18 #include <linux/module.h>
19 #include <net/ip.h>
20 #include <net/xfrm.h>
21 #include <net/esp.h>
22 #include <linux/scatterlist.h>
23 #include <linux/kernel.h>
24 #include <linux/slab.h>
25 #include <linux/spinlock.h>
26 #include <net/ip6_route.h>
27 #include <net/ipv6.h>
28 #include <linux/icmpv6.h>
29 
30 static __u16 esp6_nexthdr_esp_offset(struct ipv6hdr *ipv6_hdr, int nhlen)
31 {
32 	int off = sizeof(struct ipv6hdr);
33 	struct ipv6_opt_hdr *exthdr;
34 
35 	if (likely(ipv6_hdr->nexthdr == NEXTHDR_ESP))
36 		return offsetof(struct ipv6hdr, nexthdr);
37 
38 	while (off < nhlen) {
39 		exthdr = (void *)ipv6_hdr + off;
40 		if (exthdr->nexthdr == NEXTHDR_ESP)
41 			return off;
42 
43 		off += ipv6_optlen(exthdr);
44 	}
45 
46 	return 0;
47 }
48 
49 static struct sk_buff *esp6_gro_receive(struct list_head *head,
50 					struct sk_buff *skb)
51 {
52 	int offset = skb_gro_offset(skb);
53 	struct xfrm_offload *xo;
54 	struct xfrm_state *x;
55 	__be32 seq;
56 	__be32 spi;
57 	int nhoff;
58 	int err;
59 
60 	if (!pskb_pull(skb, offset))
61 		return NULL;
62 
63 	if ((err = xfrm_parse_spi(skb, IPPROTO_ESP, &spi, &seq)) != 0)
64 		goto out;
65 
66 	xo = xfrm_offload(skb);
67 	if (!xo || !(xo->flags & CRYPTO_DONE)) {
68 		struct sec_path *sp = secpath_set(skb);
69 
70 		if (!sp)
71 			goto out;
72 
73 		if (sp->len == XFRM_MAX_DEPTH)
74 			goto out_reset;
75 
76 		x = xfrm_state_lookup(dev_net(skb->dev), skb->mark,
77 				      (xfrm_address_t *)&ipv6_hdr(skb)->daddr,
78 				      spi, IPPROTO_ESP, AF_INET6);
79 		if (!x)
80 			goto out_reset;
81 
82 		sp->xvec[sp->len++] = x;
83 		sp->olen++;
84 
85 		xo = xfrm_offload(skb);
86 		if (!xo) {
87 			xfrm_state_put(x);
88 			goto out_reset;
89 		}
90 	}
91 
92 	xo->flags |= XFRM_GRO;
93 
94 	nhoff = esp6_nexthdr_esp_offset(ipv6_hdr(skb), offset);
95 	if (!nhoff)
96 		goto out;
97 
98 	IP6CB(skb)->nhoff = nhoff;
99 	XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6 = NULL;
100 	XFRM_SPI_SKB_CB(skb)->family = AF_INET6;
101 	XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct ipv6hdr, daddr);
102 	XFRM_SPI_SKB_CB(skb)->seq = seq;
103 
104 	/* We don't need to handle errors from xfrm_input, it does all
105 	 * the error handling and frees the resources on error. */
106 	xfrm_input(skb, IPPROTO_ESP, spi, -2);
107 
108 	return ERR_PTR(-EINPROGRESS);
109 out_reset:
110 	secpath_reset(skb);
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 *xfrm6_tunnel_gso_segment(struct xfrm_state *x,
137 						struct sk_buff *skb,
138 						netdev_features_t features)
139 {
140 	__skb_push(skb, skb->mac_len);
141 	return skb_mac_gso_segment(skb, features);
142 }
143 
144 static struct sk_buff *xfrm6_transport_gso_segment(struct xfrm_state *x,
145 						   struct sk_buff *skb,
146 						   netdev_features_t features)
147 {
148 	const struct net_offload *ops;
149 	struct sk_buff *segs = ERR_PTR(-EINVAL);
150 	struct xfrm_offload *xo = xfrm_offload(skb);
151 
152 	skb->transport_header += x->props.header_len;
153 	ops = rcu_dereference(inet6_offloads[xo->proto]);
154 	if (likely(ops && ops->callbacks.gso_segment))
155 		segs = ops->callbacks.gso_segment(skb, features);
156 
157 	return segs;
158 }
159 
160 static struct sk_buff *xfrm6_outer_mode_gso_segment(struct xfrm_state *x,
161 						    struct sk_buff *skb,
162 						    netdev_features_t features)
163 {
164 	switch (x->outer_mode.encap) {
165 	case XFRM_MODE_TUNNEL:
166 		return xfrm6_tunnel_gso_segment(x, skb, features);
167 	case XFRM_MODE_TRANSPORT:
168 		return xfrm6_transport_gso_segment(x, skb, features);
169 	}
170 
171 	return ERR_PTR(-EOPNOTSUPP);
172 }
173 
174 static struct sk_buff *esp6_gso_segment(struct sk_buff *skb,
175 				        netdev_features_t features)
176 {
177 	struct xfrm_state *x;
178 	struct ip_esp_hdr *esph;
179 	struct crypto_aead *aead;
180 	netdev_features_t esp_features = features;
181 	struct xfrm_offload *xo = xfrm_offload(skb);
182 	struct sec_path *sp;
183 
184 	if (!xo)
185 		return ERR_PTR(-EINVAL);
186 
187 	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_ESP))
188 		return ERR_PTR(-EINVAL);
189 
190 	sp = skb_sec_path(skb);
191 	x = sp->xvec[sp->len - 1];
192 	aead = x->data;
193 	esph = ip_esp_hdr(skb);
194 
195 	if (esph->spi != x->id.spi)
196 		return ERR_PTR(-EINVAL);
197 
198 	if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
199 		return ERR_PTR(-EINVAL);
200 
201 	__skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
202 
203 	skb->encap_hdr_csum = 1;
204 
205 	if (!(features & NETIF_F_HW_ESP) || x->xso.dev != skb->dev)
206 		esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK);
207 	else if (!(features & NETIF_F_HW_ESP_TX_CSUM))
208 		esp_features = features & ~NETIF_F_CSUM_MASK;
209 
210 	xo->flags |= XFRM_GSO_SEGMENT;
211 
212 	return xfrm6_outer_mode_gso_segment(x, skb, esp_features);
213 }
214 
215 static int esp6_input_tail(struct xfrm_state *x, struct sk_buff *skb)
216 {
217 	struct crypto_aead *aead = x->data;
218 	struct xfrm_offload *xo = xfrm_offload(skb);
219 
220 	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
221 		return -EINVAL;
222 
223 	if (!(xo->flags & CRYPTO_DONE))
224 		skb->ip_summed = CHECKSUM_NONE;
225 
226 	return esp6_input_done2(skb, 0);
227 }
228 
229 static int esp6_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_t features)
230 {
231 	int len;
232 	int err;
233 	int alen;
234 	int blksize;
235 	struct xfrm_offload *xo;
236 	struct ip_esp_hdr *esph;
237 	struct crypto_aead *aead;
238 	struct esp_info esp;
239 	bool hw_offload = true;
240 	__u32 seq;
241 
242 	esp.inplace = true;
243 
244 	xo = xfrm_offload(skb);
245 
246 	if (!xo)
247 		return -EINVAL;
248 
249 	if (!(features & NETIF_F_HW_ESP) || x->xso.dev != skb->dev) {
250 		xo->flags |= CRYPTO_FALLBACK;
251 		hw_offload = false;
252 	}
253 
254 	esp.proto = xo->proto;
255 
256 	/* skb is pure payload to encrypt */
257 
258 	aead = x->data;
259 	alen = crypto_aead_authsize(aead);
260 
261 	esp.tfclen = 0;
262 	/* XXX: Add support for tfc padding here. */
263 
264 	blksize = ALIGN(crypto_aead_blocksize(aead), 4);
265 	esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
266 	esp.plen = esp.clen - skb->len - esp.tfclen;
267 	esp.tailen = esp.tfclen + esp.plen + alen;
268 
269 	if (!hw_offload || (hw_offload && !skb_is_gso(skb))) {
270 		esp.nfrags = esp6_output_head(x, skb, &esp);
271 		if (esp.nfrags < 0)
272 			return esp.nfrags;
273 	}
274 
275 	seq = xo->seq.low;
276 
277 	esph = ip_esp_hdr(skb);
278 	esph->spi = x->id.spi;
279 
280 	skb_push(skb, -skb_network_offset(skb));
281 
282 	if (xo->flags & XFRM_GSO_SEGMENT) {
283 		esph->seq_no = htonl(seq);
284 
285 		if (!skb_is_gso(skb))
286 			xo->seq.low++;
287 		else
288 			xo->seq.low += skb_shinfo(skb)->gso_segs;
289 	}
290 
291 	esp.seqno = cpu_to_be64(xo->seq.low + ((u64)xo->seq.hi << 32));
292 
293 	len = skb->len - sizeof(struct ipv6hdr);
294 	if (len > IPV6_MAXPLEN)
295 		len = 0;
296 
297 	ipv6_hdr(skb)->payload_len = htons(len);
298 
299 	if (hw_offload)
300 		return 0;
301 
302 	err = esp6_output_tail(x, skb, &esp);
303 	if (err)
304 		return err;
305 
306 	secpath_reset(skb);
307 
308 	return 0;
309 }
310 
311 static const struct net_offload esp6_offload = {
312 	.callbacks = {
313 		.gro_receive = esp6_gro_receive,
314 		.gso_segment = esp6_gso_segment,
315 	},
316 };
317 
318 static const struct xfrm_type_offload esp6_type_offload = {
319 	.description	= "ESP6 OFFLOAD",
320 	.owner		= THIS_MODULE,
321 	.proto	     	= IPPROTO_ESP,
322 	.input_tail	= esp6_input_tail,
323 	.xmit		= esp6_xmit,
324 	.encap		= esp6_gso_encap,
325 };
326 
327 static int __init esp6_offload_init(void)
328 {
329 	if (xfrm_register_type_offload(&esp6_type_offload, AF_INET6) < 0) {
330 		pr_info("%s: can't add xfrm type offload\n", __func__);
331 		return -EAGAIN;
332 	}
333 
334 	return inet6_add_offload(&esp6_offload, IPPROTO_ESP);
335 }
336 
337 static void __exit esp6_offload_exit(void)
338 {
339 	xfrm_unregister_type_offload(&esp6_type_offload, AF_INET6);
340 	inet6_del_offload(&esp6_offload, IPPROTO_ESP);
341 }
342 
343 module_init(esp6_offload_init);
344 module_exit(esp6_offload_exit);
345 MODULE_LICENSE("GPL");
346 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
347 MODULE_ALIAS_XFRM_OFFLOAD_TYPE(AF_INET6, XFRM_PROTO_ESP);
348