xref: /openbmc/linux/net/ipv6/esp6_offload.c (revision b2765275) 
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 		skb->mark = xfrm_smark_get(skb->mark, x);
83 
84 		sp->xvec[sp->len++] = x;
85 		sp->olen++;
86 
87 		xo = xfrm_offload(skb);
88 		if (!xo) {
89 			xfrm_state_put(x);
90 			goto out_reset;
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_reset:
112 	secpath_reset(skb);
113 out:
114 	skb_push(skb, offset);
115 	NAPI_GRO_CB(skb)->same_flow = 0;
116 	NAPI_GRO_CB(skb)->flush = 1;
117 
118 	return NULL;
119 }
120 
121 static void esp6_gso_encap(struct xfrm_state *x, struct sk_buff *skb)
122 {
123 	struct ip_esp_hdr *esph;
124 	struct ipv6hdr *iph = ipv6_hdr(skb);
125 	struct xfrm_offload *xo = xfrm_offload(skb);
126 	int proto = iph->nexthdr;
127 
128 	skb_push(skb, -skb_network_offset(skb));
129 	esph = ip_esp_hdr(skb);
130 	*skb_mac_header(skb) = IPPROTO_ESP;
131 
132 	esph->spi = x->id.spi;
133 	esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
134 
135 	xo->proto = proto;
136 }
137 
138 static struct sk_buff *xfrm6_tunnel_gso_segment(struct xfrm_state *x,
139 						struct sk_buff *skb,
140 						netdev_features_t features)
141 {
142 	__skb_push(skb, skb->mac_len);
143 	return skb_mac_gso_segment(skb, features);
144 }
145 
146 static struct sk_buff *xfrm6_transport_gso_segment(struct xfrm_state *x,
147 						   struct sk_buff *skb,
148 						   netdev_features_t features)
149 {
150 	const struct net_offload *ops;
151 	struct sk_buff *segs = ERR_PTR(-EINVAL);
152 	struct xfrm_offload *xo = xfrm_offload(skb);
153 
154 	skb->transport_header += x->props.header_len;
155 	ops = rcu_dereference(inet6_offloads[xo->proto]);
156 	if (likely(ops && ops->callbacks.gso_segment))
157 		segs = ops->callbacks.gso_segment(skb, features);
158 
159 	return segs;
160 }
161 
162 static struct sk_buff *xfrm6_outer_mode_gso_segment(struct xfrm_state *x,
163 						    struct sk_buff *skb,
164 						    netdev_features_t features)
165 {
166 	switch (x->outer_mode.encap) {
167 	case XFRM_MODE_TUNNEL:
168 		return xfrm6_tunnel_gso_segment(x, skb, features);
169 	case XFRM_MODE_TRANSPORT:
170 		return xfrm6_transport_gso_segment(x, skb, features);
171 	}
172 
173 	return ERR_PTR(-EOPNOTSUPP);
174 }
175 
176 static struct sk_buff *esp6_gso_segment(struct sk_buff *skb,
177 				        netdev_features_t features)
178 {
179 	struct xfrm_state *x;
180 	struct ip_esp_hdr *esph;
181 	struct crypto_aead *aead;
182 	netdev_features_t esp_features = features;
183 	struct xfrm_offload *xo = xfrm_offload(skb);
184 	struct sec_path *sp;
185 
186 	if (!xo)
187 		return ERR_PTR(-EINVAL);
188 
189 	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_ESP))
190 		return ERR_PTR(-EINVAL);
191 
192 	sp = skb_sec_path(skb);
193 	x = sp->xvec[sp->len - 1];
194 	aead = x->data;
195 	esph = ip_esp_hdr(skb);
196 
197 	if (esph->spi != x->id.spi)
198 		return ERR_PTR(-EINVAL);
199 
200 	if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
201 		return ERR_PTR(-EINVAL);
202 
203 	__skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
204 
205 	skb->encap_hdr_csum = 1;
206 
207 	if (!(features & NETIF_F_HW_ESP) || x->xso.dev != skb->dev)
208 		esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK);
209 	else if (!(features & NETIF_F_HW_ESP_TX_CSUM))
210 		esp_features = features & ~NETIF_F_CSUM_MASK;
211 
212 	xo->flags |= XFRM_GSO_SEGMENT;
213 
214 	return xfrm6_outer_mode_gso_segment(x, skb, esp_features);
215 }
216 
217 static int esp6_input_tail(struct xfrm_state *x, struct sk_buff *skb)
218 {
219 	struct crypto_aead *aead = x->data;
220 	struct xfrm_offload *xo = xfrm_offload(skb);
221 
222 	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
223 		return -EINVAL;
224 
225 	if (!(xo->flags & CRYPTO_DONE))
226 		skb->ip_summed = CHECKSUM_NONE;
227 
228 	return esp6_input_done2(skb, 0);
229 }
230 
231 static int esp6_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_t features)
232 {
233 	int len;
234 	int err;
235 	int alen;
236 	int blksize;
237 	struct xfrm_offload *xo;
238 	struct ip_esp_hdr *esph;
239 	struct crypto_aead *aead;
240 	struct esp_info esp;
241 	bool hw_offload = true;
242 	__u32 seq;
243 
244 	esp.inplace = true;
245 
246 	xo = xfrm_offload(skb);
247 
248 	if (!xo)
249 		return -EINVAL;
250 
251 	if (!(features & NETIF_F_HW_ESP) || x->xso.dev != skb->dev) {
252 		xo->flags |= CRYPTO_FALLBACK;
253 		hw_offload = false;
254 	}
255 
256 	esp.proto = xo->proto;
257 
258 	/* skb is pure payload to encrypt */
259 
260 	aead = x->data;
261 	alen = crypto_aead_authsize(aead);
262 
263 	esp.tfclen = 0;
264 	/* XXX: Add support for tfc padding here. */
265 
266 	blksize = ALIGN(crypto_aead_blocksize(aead), 4);
267 	esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
268 	esp.plen = esp.clen - skb->len - esp.tfclen;
269 	esp.tailen = esp.tfclen + esp.plen + alen;
270 
271 	if (!hw_offload || (hw_offload && !skb_is_gso(skb))) {
272 		esp.nfrags = esp6_output_head(x, skb, &esp);
273 		if (esp.nfrags < 0)
274 			return esp.nfrags;
275 	}
276 
277 	seq = xo->seq.low;
278 
279 	esph = ip_esp_hdr(skb);
280 	esph->spi = x->id.spi;
281 
282 	skb_push(skb, -skb_network_offset(skb));
283 
284 	if (xo->flags & XFRM_GSO_SEGMENT) {
285 		esph->seq_no = htonl(seq);
286 
287 		if (!skb_is_gso(skb))
288 			xo->seq.low++;
289 		else
290 			xo->seq.low += skb_shinfo(skb)->gso_segs;
291 	}
292 
293 	esp.seqno = cpu_to_be64(xo->seq.low + ((u64)xo->seq.hi << 32));
294 
295 	len = skb->len - sizeof(struct ipv6hdr);
296 	if (len > IPV6_MAXPLEN)
297 		len = 0;
298 
299 	ipv6_hdr(skb)->payload_len = htons(len);
300 
301 	if (hw_offload)
302 		return 0;
303 
304 	err = esp6_output_tail(x, skb, &esp);
305 	if (err)
306 		return err;
307 
308 	secpath_reset(skb);
309 
310 	return 0;
311 }
312 
313 static const struct net_offload esp6_offload = {
314 	.callbacks = {
315 		.gro_receive = esp6_gro_receive,
316 		.gso_segment = esp6_gso_segment,
317 	},
318 };
319 
320 static const struct xfrm_type_offload esp6_type_offload = {
321 	.description	= "ESP6 OFFLOAD",
322 	.owner		= THIS_MODULE,
323 	.proto	     	= IPPROTO_ESP,
324 	.input_tail	= esp6_input_tail,
325 	.xmit		= esp6_xmit,
326 	.encap		= esp6_gso_encap,
327 };
328 
329 static int __init esp6_offload_init(void)
330 {
331 	if (xfrm_register_type_offload(&esp6_type_offload, AF_INET6) < 0) {
332 		pr_info("%s: can't add xfrm type offload\n", __func__);
333 		return -EAGAIN;
334 	}
335 
336 	return inet6_add_offload(&esp6_offload, IPPROTO_ESP);
337 }
338 
339 static void __exit esp6_offload_exit(void)
340 {
341 	xfrm_unregister_type_offload(&esp6_type_offload, AF_INET6);
342 	inet6_del_offload(&esp6_offload, IPPROTO_ESP);
343 }
344 
345 module_init(esp6_offload_init);
346 module_exit(esp6_offload_exit);
347 MODULE_LICENSE("GPL");
348 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
349 MODULE_ALIAS_XFRM_OFFLOAD_TYPE(AF_INET6, XFRM_PROTO_ESP);
350