xref: /openbmc/linux/net/ipv6/esp6_offload.c (revision 703e7713) 
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/gso.h>
21 #include <net/ip.h>
22 #include <net/xfrm.h>
23 #include <net/esp.h>
24 #include <linux/scatterlist.h>
25 #include <linux/kernel.h>
26 #include <linux/slab.h>
27 #include <linux/spinlock.h>
28 #include <net/ip6_route.h>
29 #include <net/ipv6.h>
30 #include <linux/icmpv6.h>
31 
32 static __u16 esp6_nexthdr_esp_offset(struct ipv6hdr *ipv6_hdr, int nhlen)
33 {
34 	int off = sizeof(struct ipv6hdr);
35 	struct ipv6_opt_hdr *exthdr;
36 
37 	if (likely(ipv6_hdr->nexthdr == NEXTHDR_ESP))
38 		return offsetof(struct ipv6hdr, nexthdr);
39 
40 	while (off < nhlen) {
41 		exthdr = (void *)ipv6_hdr + off;
42 		if (exthdr->nexthdr == NEXTHDR_ESP)
43 			return off;
44 
45 		off += ipv6_optlen(exthdr);
46 	}
47 
48 	return 0;
49 }
50 
51 static struct sk_buff *esp6_gro_receive(struct list_head *head,
52 					struct sk_buff *skb)
53 {
54 	int offset = skb_gro_offset(skb);
55 	struct xfrm_offload *xo;
56 	struct xfrm_state *x;
57 	__be32 seq;
58 	__be32 spi;
59 	int nhoff;
60 
61 	if (!pskb_pull(skb, offset))
62 		return NULL;
63 
64 	if (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 	__be16 type = x->inner_mode.family == AF_INET ? htons(ETH_P_IP)
149 						      : htons(ETH_P_IPV6);
150 
151 	return skb_eth_gso_segment(skb, features, type);
152 }
153 
154 static struct sk_buff *xfrm6_transport_gso_segment(struct xfrm_state *x,
155 						   struct sk_buff *skb,
156 						   netdev_features_t features)
157 {
158 	const struct net_offload *ops;
159 	struct sk_buff *segs = ERR_PTR(-EINVAL);
160 	struct xfrm_offload *xo = xfrm_offload(skb);
161 
162 	skb->transport_header += x->props.header_len;
163 	ops = rcu_dereference(inet6_offloads[xo->proto]);
164 	if (likely(ops && ops->callbacks.gso_segment))
165 		segs = ops->callbacks.gso_segment(skb, features);
166 
167 	return segs;
168 }
169 
170 static struct sk_buff *xfrm6_beet_gso_segment(struct xfrm_state *x,
171 					      struct sk_buff *skb,
172 					      netdev_features_t features)
173 {
174 	struct xfrm_offload *xo = xfrm_offload(skb);
175 	struct sk_buff *segs = ERR_PTR(-EINVAL);
176 	const struct net_offload *ops;
177 	u8 proto = xo->proto;
178 
179 	skb->transport_header += x->props.header_len;
180 
181 	if (x->sel.family != AF_INET6) {
182 		skb->transport_header -=
183 			(sizeof(struct ipv6hdr) - sizeof(struct iphdr));
184 
185 		if (proto == IPPROTO_BEETPH) {
186 			struct ip_beet_phdr *ph =
187 				(struct ip_beet_phdr *)skb->data;
188 
189 			skb->transport_header += ph->hdrlen * 8;
190 			proto = ph->nexthdr;
191 		} else {
192 			skb->transport_header -= IPV4_BEET_PHMAXLEN;
193 		}
194 
195 		if (proto == IPPROTO_TCP)
196 			skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV6;
197 	} else {
198 		__be16 frag;
199 
200 		skb->transport_header +=
201 			ipv6_skip_exthdr(skb, 0, &proto, &frag);
202 	}
203 
204 	if (proto == IPPROTO_IPIP)
205 		skb_shinfo(skb)->gso_type |= SKB_GSO_IPXIP6;
206 
207 	__skb_pull(skb, skb_transport_offset(skb));
208 	ops = rcu_dereference(inet6_offloads[proto]);
209 	if (likely(ops && ops->callbacks.gso_segment))
210 		segs = ops->callbacks.gso_segment(skb, features);
211 
212 	return segs;
213 }
214 
215 static struct sk_buff *xfrm6_outer_mode_gso_segment(struct xfrm_state *x,
216 						    struct sk_buff *skb,
217 						    netdev_features_t features)
218 {
219 	switch (x->outer_mode.encap) {
220 	case XFRM_MODE_TUNNEL:
221 		return xfrm6_tunnel_gso_segment(x, skb, features);
222 	case XFRM_MODE_TRANSPORT:
223 		return xfrm6_transport_gso_segment(x, skb, features);
224 	case XFRM_MODE_BEET:
225 		return xfrm6_beet_gso_segment(x, skb, features);
226 	}
227 
228 	return ERR_PTR(-EOPNOTSUPP);
229 }
230 
231 static struct sk_buff *esp6_gso_segment(struct sk_buff *skb,
232 				        netdev_features_t features)
233 {
234 	struct xfrm_state *x;
235 	struct ip_esp_hdr *esph;
236 	struct crypto_aead *aead;
237 	netdev_features_t esp_features = features;
238 	struct xfrm_offload *xo = xfrm_offload(skb);
239 	struct sec_path *sp;
240 
241 	if (!xo)
242 		return ERR_PTR(-EINVAL);
243 
244 	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_ESP))
245 		return ERR_PTR(-EINVAL);
246 
247 	sp = skb_sec_path(skb);
248 	x = sp->xvec[sp->len - 1];
249 	aead = x->data;
250 	esph = ip_esp_hdr(skb);
251 
252 	if (esph->spi != x->id.spi)
253 		return ERR_PTR(-EINVAL);
254 
255 	if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
256 		return ERR_PTR(-EINVAL);
257 
258 	__skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
259 
260 	skb->encap_hdr_csum = 1;
261 
262 	if (!(features & NETIF_F_HW_ESP) || x->xso.dev != skb->dev)
263 		esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK |
264 					    NETIF_F_SCTP_CRC);
265 	else if (!(features & NETIF_F_HW_ESP_TX_CSUM))
266 		esp_features = features & ~(NETIF_F_CSUM_MASK |
267 					    NETIF_F_SCTP_CRC);
268 
269 	xo->flags |= XFRM_GSO_SEGMENT;
270 
271 	return xfrm6_outer_mode_gso_segment(x, skb, esp_features);
272 }
273 
274 static int esp6_input_tail(struct xfrm_state *x, struct sk_buff *skb)
275 {
276 	struct crypto_aead *aead = x->data;
277 	struct xfrm_offload *xo = xfrm_offload(skb);
278 
279 	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
280 		return -EINVAL;
281 
282 	if (!(xo->flags & CRYPTO_DONE))
283 		skb->ip_summed = CHECKSUM_NONE;
284 
285 	return esp6_input_done2(skb, 0);
286 }
287 
288 static int esp6_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_t features)
289 {
290 	int len;
291 	int err;
292 	int alen;
293 	int blksize;
294 	struct xfrm_offload *xo;
295 	struct crypto_aead *aead;
296 	struct esp_info esp;
297 	bool hw_offload = true;
298 	__u32 seq;
299 
300 	esp.inplace = true;
301 
302 	xo = xfrm_offload(skb);
303 
304 	if (!xo)
305 		return -EINVAL;
306 
307 	if (!(features & NETIF_F_HW_ESP) || x->xso.dev != skb->dev) {
308 		xo->flags |= CRYPTO_FALLBACK;
309 		hw_offload = false;
310 	}
311 
312 	esp.proto = xo->proto;
313 
314 	/* skb is pure payload to encrypt */
315 
316 	aead = x->data;
317 	alen = crypto_aead_authsize(aead);
318 
319 	esp.tfclen = 0;
320 	/* XXX: Add support for tfc padding here. */
321 
322 	blksize = ALIGN(crypto_aead_blocksize(aead), 4);
323 	esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
324 	esp.plen = esp.clen - skb->len - esp.tfclen;
325 	esp.tailen = esp.tfclen + esp.plen + alen;
326 
327 	if (!hw_offload || !skb_is_gso(skb)) {
328 		esp.nfrags = esp6_output_head(x, skb, &esp);
329 		if (esp.nfrags < 0)
330 			return esp.nfrags;
331 	}
332 
333 	seq = xo->seq.low;
334 
335 	esp.esph = ip_esp_hdr(skb);
336 	esp.esph->spi = x->id.spi;
337 
338 	skb_push(skb, -skb_network_offset(skb));
339 
340 	if (xo->flags & XFRM_GSO_SEGMENT) {
341 		esp.esph->seq_no = htonl(seq);
342 
343 		if (!skb_is_gso(skb))
344 			xo->seq.low++;
345 		else
346 			xo->seq.low += skb_shinfo(skb)->gso_segs;
347 	}
348 
349 	if (xo->seq.low < seq)
350 		xo->seq.hi++;
351 
352 	esp.seqno = cpu_to_be64(xo->seq.low + ((u64)xo->seq.hi << 32));
353 
354 	len = skb->len - sizeof(struct ipv6hdr);
355 	if (len > IPV6_MAXPLEN)
356 		len = 0;
357 
358 	ipv6_hdr(skb)->payload_len = htons(len);
359 
360 	if (hw_offload) {
361 		if (!skb_ext_add(skb, SKB_EXT_SEC_PATH))
362 			return -ENOMEM;
363 
364 		xo = xfrm_offload(skb);
365 		if (!xo)
366 			return -EINVAL;
367 
368 		xo->flags |= XFRM_XMIT;
369 		return 0;
370 	}
371 
372 	err = esp6_output_tail(x, skb, &esp);
373 	if (err)
374 		return err;
375 
376 	secpath_reset(skb);
377 
378 	if (skb_needs_linearize(skb, skb->dev->features) &&
379 	    __skb_linearize(skb))
380 		return -ENOMEM;
381 	return 0;
382 }
383 
384 static const struct net_offload esp6_offload = {
385 	.callbacks = {
386 		.gro_receive = esp6_gro_receive,
387 		.gso_segment = esp6_gso_segment,
388 	},
389 };
390 
391 static const struct xfrm_type_offload esp6_type_offload = {
392 	.owner		= THIS_MODULE,
393 	.proto	     	= IPPROTO_ESP,
394 	.input_tail	= esp6_input_tail,
395 	.xmit		= esp6_xmit,
396 	.encap		= esp6_gso_encap,
397 };
398 
399 static int __init esp6_offload_init(void)
400 {
401 	if (xfrm_register_type_offload(&esp6_type_offload, AF_INET6) < 0) {
402 		pr_info("%s: can't add xfrm type offload\n", __func__);
403 		return -EAGAIN;
404 	}
405 
406 	return inet6_add_offload(&esp6_offload, IPPROTO_ESP);
407 }
408 
409 static void __exit esp6_offload_exit(void)
410 {
411 	xfrm_unregister_type_offload(&esp6_type_offload, AF_INET6);
412 	inet6_del_offload(&esp6_offload, IPPROTO_ESP);
413 }
414 
415 module_init(esp6_offload_init);
416 module_exit(esp6_offload_exit);
417 MODULE_LICENSE("GPL");
418 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
419 MODULE_ALIAS_XFRM_OFFLOAD_TYPE(AF_INET6, XFRM_PROTO_ESP);
420 MODULE_DESCRIPTION("IPV6 GSO/GRO offload support");
421