xref: /openbmc/linux/net/ipv6/esp6_offload.c (revision 0aa7be05) 
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/gro.h>
20 #include <net/ip.h>
21 #include <net/xfrm.h>
22 #include <net/esp.h>
23 #include <linux/scatterlist.h>
24 #include <linux/kernel.h>
25 #include <linux/slab.h>
26 #include <linux/spinlock.h>
27 #include <net/ip6_route.h>
28 #include <net/ipv6.h>
29 #include <linux/icmpv6.h>
30 
31 static __u16 esp6_nexthdr_esp_offset(struct ipv6hdr *ipv6_hdr, int nhlen)
32 {
33 	int off = sizeof(struct ipv6hdr);
34 	struct ipv6_opt_hdr *exthdr;
35 
36 	if (likely(ipv6_hdr->nexthdr == NEXTHDR_ESP))
37 		return offsetof(struct ipv6hdr, nexthdr);
38 
39 	while (off < nhlen) {
40 		exthdr = (void *)ipv6_hdr + off;
41 		if (exthdr->nexthdr == NEXTHDR_ESP)
42 			return off;
43 
44 		off += ipv6_optlen(exthdr);
45 	}
46 
47 	return 0;
48 }
49 
50 static struct sk_buff *esp6_gro_receive(struct list_head *head,
51 					struct sk_buff *skb)
52 {
53 	int offset = skb_gro_offset(skb);
54 	struct xfrm_offload *xo;
55 	struct xfrm_state *x;
56 	__be32 seq;
57 	__be32 spi;
58 	int nhoff;
59 	int err;
60 
61 	if (!pskb_pull(skb, offset))
62 		return NULL;
63 
64 	if ((err = xfrm_parse_spi(skb, IPPROTO_ESP, &spi, &seq)) != 0)
65 		goto out;
66 
67 	xo = xfrm_offload(skb);
68 	if (!xo || !(xo->flags & CRYPTO_DONE)) {
69 		struct sec_path *sp = secpath_set(skb);
70 
71 		if (!sp)
72 			goto out;
73 
74 		if (sp->len == XFRM_MAX_DEPTH)
75 			goto out_reset;
76 
77 		x = xfrm_state_lookup(dev_net(skb->dev), skb->mark,
78 				      (xfrm_address_t *)&ipv6_hdr(skb)->daddr,
79 				      spi, IPPROTO_ESP, AF_INET6);
80 		if (!x)
81 			goto out_reset;
82 
83 		skb->mark = xfrm_smark_get(skb->mark, x);
84 
85 		sp->xvec[sp->len++] = x;
86 		sp->olen++;
87 
88 		xo = xfrm_offload(skb);
89 		if (!xo)
90 			goto out_reset;
91 	}
92 
93 	xo->flags |= XFRM_GRO;
94 
95 	nhoff = esp6_nexthdr_esp_offset(ipv6_hdr(skb), offset);
96 	if (!nhoff)
97 		goto out;
98 
99 	IP6CB(skb)->nhoff = nhoff;
100 	XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6 = NULL;
101 	XFRM_SPI_SKB_CB(skb)->family = AF_INET6;
102 	XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct ipv6hdr, daddr);
103 	XFRM_SPI_SKB_CB(skb)->seq = seq;
104 
105 	/* We don't need to handle errors from xfrm_input, it does all
106 	 * the error handling and frees the resources on error. */
107 	xfrm_input(skb, IPPROTO_ESP, spi, -2);
108 
109 	return ERR_PTR(-EINPROGRESS);
110 out_reset:
111 	secpath_reset(skb);
112 out:
113 	skb_push(skb, offset);
114 	NAPI_GRO_CB(skb)->same_flow = 0;
115 	NAPI_GRO_CB(skb)->flush = 1;
116 
117 	return NULL;
118 }
119 
120 static void esp6_gso_encap(struct xfrm_state *x, struct sk_buff *skb)
121 {
122 	struct ip_esp_hdr *esph;
123 	struct ipv6hdr *iph = ipv6_hdr(skb);
124 	struct xfrm_offload *xo = xfrm_offload(skb);
125 	u8 proto = iph->nexthdr;
126 
127 	skb_push(skb, -skb_network_offset(skb));
128 
129 	if (x->outer_mode.encap == XFRM_MODE_TRANSPORT) {
130 		__be16 frag;
131 
132 		ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &proto, &frag);
133 	}
134 
135 	esph = ip_esp_hdr(skb);
136 	*skb_mac_header(skb) = IPPROTO_ESP;
137 
138 	esph->spi = x->id.spi;
139 	esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
140 
141 	xo->proto = proto;
142 }
143 
144 static struct sk_buff *xfrm6_tunnel_gso_segment(struct xfrm_state *x,
145 						struct sk_buff *skb,
146 						netdev_features_t features)
147 {
148 	return skb_eth_gso_segment(skb, features, htons(ETH_P_IPV6));
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 	if (proto == IPPROTO_IPIP)
202 		skb_shinfo(skb)->gso_type |= SKB_GSO_IPXIP6;
203 
204 	__skb_pull(skb, skb_transport_offset(skb));
205 	ops = rcu_dereference(inet6_offloads[proto]);
206 	if (likely(ops && ops->callbacks.gso_segment))
207 		segs = ops->callbacks.gso_segment(skb, features);
208 
209 	return segs;
210 }
211 
212 static struct sk_buff *xfrm6_outer_mode_gso_segment(struct xfrm_state *x,
213 						    struct sk_buff *skb,
214 						    netdev_features_t features)
215 {
216 	switch (x->outer_mode.encap) {
217 	case XFRM_MODE_TUNNEL:
218 		return xfrm6_tunnel_gso_segment(x, skb, features);
219 	case XFRM_MODE_TRANSPORT:
220 		return xfrm6_transport_gso_segment(x, skb, features);
221 	case XFRM_MODE_BEET:
222 		return xfrm6_beet_gso_segment(x, skb, features);
223 	}
224 
225 	return ERR_PTR(-EOPNOTSUPP);
226 }
227 
228 static struct sk_buff *esp6_gso_segment(struct sk_buff *skb,
229 				        netdev_features_t features)
230 {
231 	struct xfrm_state *x;
232 	struct ip_esp_hdr *esph;
233 	struct crypto_aead *aead;
234 	netdev_features_t esp_features = features;
235 	struct xfrm_offload *xo = xfrm_offload(skb);
236 	struct sec_path *sp;
237 
238 	if (!xo)
239 		return ERR_PTR(-EINVAL);
240 
241 	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_ESP))
242 		return ERR_PTR(-EINVAL);
243 
244 	sp = skb_sec_path(skb);
245 	x = sp->xvec[sp->len - 1];
246 	aead = x->data;
247 	esph = ip_esp_hdr(skb);
248 
249 	if (esph->spi != x->id.spi)
250 		return ERR_PTR(-EINVAL);
251 
252 	if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
253 		return ERR_PTR(-EINVAL);
254 
255 	__skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
256 
257 	skb->encap_hdr_csum = 1;
258 
259 	if (!(features & NETIF_F_HW_ESP) || x->xso.dev != skb->dev)
260 		esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK |
261 					    NETIF_F_SCTP_CRC);
262 	else if (!(features & NETIF_F_HW_ESP_TX_CSUM))
263 		esp_features = features & ~(NETIF_F_CSUM_MASK |
264 					    NETIF_F_SCTP_CRC);
265 
266 	xo->flags |= XFRM_GSO_SEGMENT;
267 
268 	return xfrm6_outer_mode_gso_segment(x, skb, esp_features);
269 }
270 
271 static int esp6_input_tail(struct xfrm_state *x, struct sk_buff *skb)
272 {
273 	struct crypto_aead *aead = x->data;
274 	struct xfrm_offload *xo = xfrm_offload(skb);
275 
276 	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
277 		return -EINVAL;
278 
279 	if (!(xo->flags & CRYPTO_DONE))
280 		skb->ip_summed = CHECKSUM_NONE;
281 
282 	return esp6_input_done2(skb, 0);
283 }
284 
285 static int esp6_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_t features)
286 {
287 	int len;
288 	int err;
289 	int alen;
290 	int blksize;
291 	struct xfrm_offload *xo;
292 	struct crypto_aead *aead;
293 	struct esp_info esp;
294 	bool hw_offload = true;
295 	__u32 seq;
296 
297 	esp.inplace = true;
298 
299 	xo = xfrm_offload(skb);
300 
301 	if (!xo)
302 		return -EINVAL;
303 
304 	if (!(features & NETIF_F_HW_ESP) || x->xso.dev != skb->dev) {
305 		xo->flags |= CRYPTO_FALLBACK;
306 		hw_offload = false;
307 	}
308 
309 	esp.proto = xo->proto;
310 
311 	/* skb is pure payload to encrypt */
312 
313 	aead = x->data;
314 	alen = crypto_aead_authsize(aead);
315 
316 	esp.tfclen = 0;
317 	/* XXX: Add support for tfc padding here. */
318 
319 	blksize = ALIGN(crypto_aead_blocksize(aead), 4);
320 	esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
321 	esp.plen = esp.clen - skb->len - esp.tfclen;
322 	esp.tailen = esp.tfclen + esp.plen + alen;
323 
324 	if (!hw_offload || !skb_is_gso(skb)) {
325 		esp.nfrags = esp6_output_head(x, skb, &esp);
326 		if (esp.nfrags < 0)
327 			return esp.nfrags;
328 	}
329 
330 	seq = xo->seq.low;
331 
332 	esp.esph = ip_esp_hdr(skb);
333 	esp.esph->spi = x->id.spi;
334 
335 	skb_push(skb, -skb_network_offset(skb));
336 
337 	if (xo->flags & XFRM_GSO_SEGMENT) {
338 		esp.esph->seq_no = htonl(seq);
339 
340 		if (!skb_is_gso(skb))
341 			xo->seq.low++;
342 		else
343 			xo->seq.low += skb_shinfo(skb)->gso_segs;
344 	}
345 
346 	esp.seqno = cpu_to_be64(xo->seq.low + ((u64)xo->seq.hi << 32));
347 
348 	len = skb->len - sizeof(struct ipv6hdr);
349 	if (len > IPV6_MAXPLEN)
350 		len = 0;
351 
352 	ipv6_hdr(skb)->payload_len = htons(len);
353 
354 	if (hw_offload) {
355 		if (!skb_ext_add(skb, SKB_EXT_SEC_PATH))
356 			return -ENOMEM;
357 
358 		xo = xfrm_offload(skb);
359 		if (!xo)
360 			return -EINVAL;
361 
362 		xo->flags |= XFRM_XMIT;
363 		return 0;
364 	}
365 
366 	err = esp6_output_tail(x, skb, &esp);
367 	if (err)
368 		return err;
369 
370 	secpath_reset(skb);
371 
372 	return 0;
373 }
374 
375 static const struct net_offload esp6_offload = {
376 	.callbacks = {
377 		.gro_receive = esp6_gro_receive,
378 		.gso_segment = esp6_gso_segment,
379 	},
380 };
381 
382 static const struct xfrm_type_offload esp6_type_offload = {
383 	.owner		= THIS_MODULE,
384 	.proto	     	= IPPROTO_ESP,
385 	.input_tail	= esp6_input_tail,
386 	.xmit		= esp6_xmit,
387 	.encap		= esp6_gso_encap,
388 };
389 
390 static int __init esp6_offload_init(void)
391 {
392 	if (xfrm_register_type_offload(&esp6_type_offload, AF_INET6) < 0) {
393 		pr_info("%s: can't add xfrm type offload\n", __func__);
394 		return -EAGAIN;
395 	}
396 
397 	return inet6_add_offload(&esp6_offload, IPPROTO_ESP);
398 }
399 
400 static void __exit esp6_offload_exit(void)
401 {
402 	xfrm_unregister_type_offload(&esp6_type_offload, AF_INET6);
403 	inet6_del_offload(&esp6_offload, IPPROTO_ESP);
404 }
405 
406 module_init(esp6_offload_init);
407 module_exit(esp6_offload_exit);
408 MODULE_LICENSE("GPL");
409 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
410 MODULE_ALIAS_XFRM_OFFLOAD_TYPE(AF_INET6, XFRM_PROTO_ESP);
411 MODULE_DESCRIPTION("IPV6 GSO/GRO offload support");
412