xref: /openbmc/linux/net/ipv6/esp6_offload.c (revision a3a66c38) 
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 			goto out_reset;
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 	u8 proto = iph->nexthdr;
125 
126 	skb_push(skb, -skb_network_offset(skb));
127 
128 	if (x->outer_mode.encap == XFRM_MODE_TRANSPORT) {
129 		__be16 frag;
130 
131 		ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &proto, &frag);
132 	}
133 
134 	esph = ip_esp_hdr(skb);
135 	*skb_mac_header(skb) = IPPROTO_ESP;
136 
137 	esph->spi = x->id.spi;
138 	esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
139 
140 	xo->proto = proto;
141 }
142 
143 static struct sk_buff *xfrm6_tunnel_gso_segment(struct xfrm_state *x,
144 						struct sk_buff *skb,
145 						netdev_features_t features)
146 {
147 	__skb_push(skb, skb->mac_len);
148 	return skb_mac_gso_segment(skb, features);
149 }
150 
151 static struct sk_buff *xfrm6_transport_gso_segment(struct xfrm_state *x,
152 						   struct sk_buff *skb,
153 						   netdev_features_t features)
154 {
155 	const struct net_offload *ops;
156 	struct sk_buff *segs = ERR_PTR(-EINVAL);
157 	struct xfrm_offload *xo = xfrm_offload(skb);
158 
159 	skb->transport_header += x->props.header_len;
160 	ops = rcu_dereference(inet6_offloads[xo->proto]);
161 	if (likely(ops && ops->callbacks.gso_segment))
162 		segs = ops->callbacks.gso_segment(skb, features);
163 
164 	return segs;
165 }
166 
167 static struct sk_buff *xfrm6_beet_gso_segment(struct xfrm_state *x,
168 					      struct sk_buff *skb,
169 					      netdev_features_t features)
170 {
171 	struct xfrm_offload *xo = xfrm_offload(skb);
172 	struct sk_buff *segs = ERR_PTR(-EINVAL);
173 	const struct net_offload *ops;
174 	u8 proto = xo->proto;
175 
176 	skb->transport_header += x->props.header_len;
177 
178 	if (x->sel.family != AF_INET6) {
179 		skb->transport_header -=
180 			(sizeof(struct ipv6hdr) - sizeof(struct iphdr));
181 
182 		if (proto == IPPROTO_BEETPH) {
183 			struct ip_beet_phdr *ph =
184 				(struct ip_beet_phdr *)skb->data;
185 
186 			skb->transport_header += ph->hdrlen * 8;
187 			proto = ph->nexthdr;
188 		} else {
189 			skb->transport_header -= IPV4_BEET_PHMAXLEN;
190 		}
191 
192 		if (proto == IPPROTO_TCP)
193 			skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV6;
194 	} else {
195 		__be16 frag;
196 
197 		skb->transport_header +=
198 			ipv6_skip_exthdr(skb, 0, &proto, &frag);
199 	}
200 
201 	__skb_pull(skb, skb_transport_offset(skb));
202 	ops = rcu_dereference(inet6_offloads[proto]);
203 	if (likely(ops && ops->callbacks.gso_segment))
204 		segs = ops->callbacks.gso_segment(skb, features);
205 
206 	return segs;
207 }
208 
209 static struct sk_buff *xfrm6_outer_mode_gso_segment(struct xfrm_state *x,
210 						    struct sk_buff *skb,
211 						    netdev_features_t features)
212 {
213 	switch (x->outer_mode.encap) {
214 	case XFRM_MODE_TUNNEL:
215 		return xfrm6_tunnel_gso_segment(x, skb, features);
216 	case XFRM_MODE_TRANSPORT:
217 		return xfrm6_transport_gso_segment(x, skb, features);
218 	case XFRM_MODE_BEET:
219 		return xfrm6_beet_gso_segment(x, skb, features);
220 	}
221 
222 	return ERR_PTR(-EOPNOTSUPP);
223 }
224 
225 static struct sk_buff *esp6_gso_segment(struct sk_buff *skb,
226 				        netdev_features_t features)
227 {
228 	struct xfrm_state *x;
229 	struct ip_esp_hdr *esph;
230 	struct crypto_aead *aead;
231 	netdev_features_t esp_features = features;
232 	struct xfrm_offload *xo = xfrm_offload(skb);
233 	struct sec_path *sp;
234 
235 	if (!xo)
236 		return ERR_PTR(-EINVAL);
237 
238 	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_ESP))
239 		return ERR_PTR(-EINVAL);
240 
241 	sp = skb_sec_path(skb);
242 	x = sp->xvec[sp->len - 1];
243 	aead = x->data;
244 	esph = ip_esp_hdr(skb);
245 
246 	if (esph->spi != x->id.spi)
247 		return ERR_PTR(-EINVAL);
248 
249 	if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
250 		return ERR_PTR(-EINVAL);
251 
252 	__skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
253 
254 	skb->encap_hdr_csum = 1;
255 
256 	if (!(features & NETIF_F_HW_ESP) || x->xso.dev != skb->dev)
257 		esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK);
258 	else if (!(features & NETIF_F_HW_ESP_TX_CSUM))
259 		esp_features = features & ~NETIF_F_CSUM_MASK;
260 
261 	xo->flags |= XFRM_GSO_SEGMENT;
262 
263 	return xfrm6_outer_mode_gso_segment(x, skb, esp_features);
264 }
265 
266 static int esp6_input_tail(struct xfrm_state *x, struct sk_buff *skb)
267 {
268 	struct crypto_aead *aead = x->data;
269 	struct xfrm_offload *xo = xfrm_offload(skb);
270 
271 	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
272 		return -EINVAL;
273 
274 	if (!(xo->flags & CRYPTO_DONE))
275 		skb->ip_summed = CHECKSUM_NONE;
276 
277 	return esp6_input_done2(skb, 0);
278 }
279 
280 static int esp6_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_t features)
281 {
282 	int len;
283 	int err;
284 	int alen;
285 	int blksize;
286 	struct xfrm_offload *xo;
287 	struct crypto_aead *aead;
288 	struct esp_info esp;
289 	bool hw_offload = true;
290 	__u32 seq;
291 
292 	esp.inplace = true;
293 
294 	xo = xfrm_offload(skb);
295 
296 	if (!xo)
297 		return -EINVAL;
298 
299 	if (!(features & NETIF_F_HW_ESP) || x->xso.dev != skb->dev) {
300 		xo->flags |= CRYPTO_FALLBACK;
301 		hw_offload = false;
302 	}
303 
304 	esp.proto = xo->proto;
305 
306 	/* skb is pure payload to encrypt */
307 
308 	aead = x->data;
309 	alen = crypto_aead_authsize(aead);
310 
311 	esp.tfclen = 0;
312 	/* XXX: Add support for tfc padding here. */
313 
314 	blksize = ALIGN(crypto_aead_blocksize(aead), 4);
315 	esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
316 	esp.plen = esp.clen - skb->len - esp.tfclen;
317 	esp.tailen = esp.tfclen + esp.plen + alen;
318 
319 	if (!hw_offload || (hw_offload && !skb_is_gso(skb))) {
320 		esp.nfrags = esp6_output_head(x, skb, &esp);
321 		if (esp.nfrags < 0)
322 			return esp.nfrags;
323 	}
324 
325 	seq = xo->seq.low;
326 
327 	esp.esph = ip_esp_hdr(skb);
328 	esp.esph->spi = x->id.spi;
329 
330 	skb_push(skb, -skb_network_offset(skb));
331 
332 	if (xo->flags & XFRM_GSO_SEGMENT) {
333 		esp.esph->seq_no = htonl(seq);
334 
335 		if (!skb_is_gso(skb))
336 			xo->seq.low++;
337 		else
338 			xo->seq.low += skb_shinfo(skb)->gso_segs;
339 	}
340 
341 	esp.seqno = cpu_to_be64(xo->seq.low + ((u64)xo->seq.hi << 32));
342 
343 	len = skb->len - sizeof(struct ipv6hdr);
344 	if (len > IPV6_MAXPLEN)
345 		len = 0;
346 
347 	ipv6_hdr(skb)->payload_len = htons(len);
348 
349 	if (hw_offload)
350 		return 0;
351 
352 	err = esp6_output_tail(x, skb, &esp);
353 	if (err)
354 		return err;
355 
356 	secpath_reset(skb);
357 
358 	return 0;
359 }
360 
361 static const struct net_offload esp6_offload = {
362 	.callbacks = {
363 		.gro_receive = esp6_gro_receive,
364 		.gso_segment = esp6_gso_segment,
365 	},
366 };
367 
368 static const struct xfrm_type_offload esp6_type_offload = {
369 	.description	= "ESP6 OFFLOAD",
370 	.owner		= THIS_MODULE,
371 	.proto	     	= IPPROTO_ESP,
372 	.input_tail	= esp6_input_tail,
373 	.xmit		= esp6_xmit,
374 	.encap		= esp6_gso_encap,
375 };
376 
377 static int __init esp6_offload_init(void)
378 {
379 	if (xfrm_register_type_offload(&esp6_type_offload, AF_INET6) < 0) {
380 		pr_info("%s: can't add xfrm type offload\n", __func__);
381 		return -EAGAIN;
382 	}
383 
384 	return inet6_add_offload(&esp6_offload, IPPROTO_ESP);
385 }
386 
387 static void __exit esp6_offload_exit(void)
388 {
389 	xfrm_unregister_type_offload(&esp6_type_offload, AF_INET6);
390 	inet6_del_offload(&esp6_offload, IPPROTO_ESP);
391 }
392 
393 module_init(esp6_offload_init);
394 module_exit(esp6_offload_exit);
395 MODULE_LICENSE("GPL");
396 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
397 MODULE_ALIAS_XFRM_OFFLOAD_TYPE(AF_INET6, XFRM_PROTO_ESP);
398 MODULE_DESCRIPTION("IPV6 GSO/GRO offload support");
399