xref: /openbmc/linux/net/ipv6/esp6_offload.c (revision e7f127b2) 
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 	__skb_push(skb, skb->mac_len);
149 	return skb_mac_gso_segment(skb, features);
150 }
151 
152 static struct sk_buff *xfrm6_transport_gso_segment(struct xfrm_state *x,
153 						   struct sk_buff *skb,
154 						   netdev_features_t features)
155 {
156 	const struct net_offload *ops;
157 	struct sk_buff *segs = ERR_PTR(-EINVAL);
158 	struct xfrm_offload *xo = xfrm_offload(skb);
159 
160 	skb->transport_header += x->props.header_len;
161 	ops = rcu_dereference(inet6_offloads[xo->proto]);
162 	if (likely(ops && ops->callbacks.gso_segment))
163 		segs = ops->callbacks.gso_segment(skb, features);
164 
165 	return segs;
166 }
167 
168 static struct sk_buff *xfrm6_beet_gso_segment(struct xfrm_state *x,
169 					      struct sk_buff *skb,
170 					      netdev_features_t features)
171 {
172 	struct xfrm_offload *xo = xfrm_offload(skb);
173 	struct sk_buff *segs = ERR_PTR(-EINVAL);
174 	const struct net_offload *ops;
175 	u8 proto = xo->proto;
176 
177 	skb->transport_header += x->props.header_len;
178 
179 	if (x->sel.family != AF_INET6) {
180 		skb->transport_header -=
181 			(sizeof(struct ipv6hdr) - sizeof(struct iphdr));
182 
183 		if (proto == IPPROTO_BEETPH) {
184 			struct ip_beet_phdr *ph =
185 				(struct ip_beet_phdr *)skb->data;
186 
187 			skb->transport_header += ph->hdrlen * 8;
188 			proto = ph->nexthdr;
189 		} else {
190 			skb->transport_header -= IPV4_BEET_PHMAXLEN;
191 		}
192 
193 		if (proto == IPPROTO_TCP)
194 			skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV6;
195 	} else {
196 		__be16 frag;
197 
198 		skb->transport_header +=
199 			ipv6_skip_exthdr(skb, 0, &proto, &frag);
200 	}
201 
202 	__skb_pull(skb, skb_transport_offset(skb));
203 	ops = rcu_dereference(inet6_offloads[proto]);
204 	if (likely(ops && ops->callbacks.gso_segment))
205 		segs = ops->callbacks.gso_segment(skb, features);
206 
207 	return segs;
208 }
209 
210 static struct sk_buff *xfrm6_outer_mode_gso_segment(struct xfrm_state *x,
211 						    struct sk_buff *skb,
212 						    netdev_features_t features)
213 {
214 	switch (x->outer_mode.encap) {
215 	case XFRM_MODE_TUNNEL:
216 		return xfrm6_tunnel_gso_segment(x, skb, features);
217 	case XFRM_MODE_TRANSPORT:
218 		return xfrm6_transport_gso_segment(x, skb, features);
219 	case XFRM_MODE_BEET:
220 		return xfrm6_beet_gso_segment(x, skb, features);
221 	}
222 
223 	return ERR_PTR(-EOPNOTSUPP);
224 }
225 
226 static struct sk_buff *esp6_gso_segment(struct sk_buff *skb,
227 				        netdev_features_t features)
228 {
229 	struct xfrm_state *x;
230 	struct ip_esp_hdr *esph;
231 	struct crypto_aead *aead;
232 	netdev_features_t esp_features = features;
233 	struct xfrm_offload *xo = xfrm_offload(skb);
234 	struct sec_path *sp;
235 
236 	if (!xo)
237 		return ERR_PTR(-EINVAL);
238 
239 	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_ESP))
240 		return ERR_PTR(-EINVAL);
241 
242 	sp = skb_sec_path(skb);
243 	x = sp->xvec[sp->len - 1];
244 	aead = x->data;
245 	esph = ip_esp_hdr(skb);
246 
247 	if (esph->spi != x->id.spi)
248 		return ERR_PTR(-EINVAL);
249 
250 	if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
251 		return ERR_PTR(-EINVAL);
252 
253 	__skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
254 
255 	skb->encap_hdr_csum = 1;
256 
257 	if (!(features & NETIF_F_HW_ESP) || x->xso.dev != skb->dev)
258 		esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK |
259 					    NETIF_F_SCTP_CRC);
260 	else if (!(features & NETIF_F_HW_ESP_TX_CSUM))
261 		esp_features = features & ~(NETIF_F_CSUM_MASK |
262 					    NETIF_F_SCTP_CRC);
263 
264 	xo->flags |= XFRM_GSO_SEGMENT;
265 
266 	return xfrm6_outer_mode_gso_segment(x, skb, esp_features);
267 }
268 
269 static int esp6_input_tail(struct xfrm_state *x, struct sk_buff *skb)
270 {
271 	struct crypto_aead *aead = x->data;
272 	struct xfrm_offload *xo = xfrm_offload(skb);
273 
274 	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
275 		return -EINVAL;
276 
277 	if (!(xo->flags & CRYPTO_DONE))
278 		skb->ip_summed = CHECKSUM_NONE;
279 
280 	return esp6_input_done2(skb, 0);
281 }
282 
283 static int esp6_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_t features)
284 {
285 	int len;
286 	int err;
287 	int alen;
288 	int blksize;
289 	struct xfrm_offload *xo;
290 	struct crypto_aead *aead;
291 	struct esp_info esp;
292 	bool hw_offload = true;
293 	__u32 seq;
294 
295 	esp.inplace = true;
296 
297 	xo = xfrm_offload(skb);
298 
299 	if (!xo)
300 		return -EINVAL;
301 
302 	if (!(features & NETIF_F_HW_ESP) || x->xso.dev != skb->dev) {
303 		xo->flags |= CRYPTO_FALLBACK;
304 		hw_offload = false;
305 	}
306 
307 	esp.proto = xo->proto;
308 
309 	/* skb is pure payload to encrypt */
310 
311 	aead = x->data;
312 	alen = crypto_aead_authsize(aead);
313 
314 	esp.tfclen = 0;
315 	/* XXX: Add support for tfc padding here. */
316 
317 	blksize = ALIGN(crypto_aead_blocksize(aead), 4);
318 	esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
319 	esp.plen = esp.clen - skb->len - esp.tfclen;
320 	esp.tailen = esp.tfclen + esp.plen + alen;
321 
322 	if (!hw_offload || !skb_is_gso(skb)) {
323 		esp.nfrags = esp6_output_head(x, skb, &esp);
324 		if (esp.nfrags < 0)
325 			return esp.nfrags;
326 	}
327 
328 	seq = xo->seq.low;
329 
330 	esp.esph = ip_esp_hdr(skb);
331 	esp.esph->spi = x->id.spi;
332 
333 	skb_push(skb, -skb_network_offset(skb));
334 
335 	if (xo->flags & XFRM_GSO_SEGMENT) {
336 		esp.esph->seq_no = htonl(seq);
337 
338 		if (!skb_is_gso(skb))
339 			xo->seq.low++;
340 		else
341 			xo->seq.low += skb_shinfo(skb)->gso_segs;
342 	}
343 
344 	esp.seqno = cpu_to_be64(xo->seq.low + ((u64)xo->seq.hi << 32));
345 
346 	len = skb->len - sizeof(struct ipv6hdr);
347 	if (len > IPV6_MAXPLEN)
348 		len = 0;
349 
350 	ipv6_hdr(skb)->payload_len = htons(len);
351 
352 	if (hw_offload) {
353 		if (!skb_ext_add(skb, SKB_EXT_SEC_PATH))
354 			return -ENOMEM;
355 
356 		xo = xfrm_offload(skb);
357 		if (!xo)
358 			return -EINVAL;
359 
360 		xo->flags |= XFRM_XMIT;
361 		return 0;
362 	}
363 
364 	err = esp6_output_tail(x, skb, &esp);
365 	if (err)
366 		return err;
367 
368 	secpath_reset(skb);
369 
370 	return 0;
371 }
372 
373 static const struct net_offload esp6_offload = {
374 	.callbacks = {
375 		.gro_receive = esp6_gro_receive,
376 		.gso_segment = esp6_gso_segment,
377 	},
378 };
379 
380 static const struct xfrm_type_offload esp6_type_offload = {
381 	.owner		= THIS_MODULE,
382 	.proto	     	= IPPROTO_ESP,
383 	.input_tail	= esp6_input_tail,
384 	.xmit		= esp6_xmit,
385 	.encap		= esp6_gso_encap,
386 };
387 
388 static int __init esp6_offload_init(void)
389 {
390 	if (xfrm_register_type_offload(&esp6_type_offload, AF_INET6) < 0) {
391 		pr_info("%s: can't add xfrm type offload\n", __func__);
392 		return -EAGAIN;
393 	}
394 
395 	return inet6_add_offload(&esp6_offload, IPPROTO_ESP);
396 }
397 
398 static void __exit esp6_offload_exit(void)
399 {
400 	xfrm_unregister_type_offload(&esp6_type_offload, AF_INET6);
401 	inet6_del_offload(&esp6_offload, IPPROTO_ESP);
402 }
403 
404 module_init(esp6_offload_init);
405 module_exit(esp6_offload_exit);
406 MODULE_LICENSE("GPL");
407 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
408 MODULE_ALIAS_XFRM_OFFLOAD_TYPE(AF_INET6, XFRM_PROTO_ESP);
409 MODULE_DESCRIPTION("IPV6 GSO/GRO offload support");
410