xref: /openbmc/linux/net/ipv6/ip6_offload.c (revision ae3473231e77a3f1909d48cd144cebe5e1d049b3)
1 /*
2  *	IPV6 GSO/GRO offload support
3  *	Linux INET6 implementation
4  *
5  *	This program is free software; you can redistribute it and/or
6  *      modify it under the terms of the GNU General Public License
7  *      as published by the Free Software Foundation; either version
8  *      2 of the License, or (at your option) any later version.
9  */
10 
11 #include <linux/kernel.h>
12 #include <linux/socket.h>
13 #include <linux/netdevice.h>
14 #include <linux/skbuff.h>
15 #include <linux/printk.h>
16 
17 #include <net/protocol.h>
18 #include <net/ipv6.h>
19 #include <net/inet_common.h>
20 
21 #include "ip6_offload.h"
22 
23 static int ipv6_gso_pull_exthdrs(struct sk_buff *skb, int proto)
24 {
25 	const struct net_offload *ops = NULL;
26 
27 	for (;;) {
28 		struct ipv6_opt_hdr *opth;
29 		int len;
30 
31 		if (proto != NEXTHDR_HOP) {
32 			ops = rcu_dereference(inet6_offloads[proto]);
33 
34 			if (unlikely(!ops))
35 				break;
36 
37 			if (!(ops->flags & INET6_PROTO_GSO_EXTHDR))
38 				break;
39 		}
40 
41 		if (unlikely(!pskb_may_pull(skb, 8)))
42 			break;
43 
44 		opth = (void *)skb->data;
45 		len = ipv6_optlen(opth);
46 
47 		if (unlikely(!pskb_may_pull(skb, len)))
48 			break;
49 
50 		opth = (void *)skb->data;
51 		proto = opth->nexthdr;
52 		__skb_pull(skb, len);
53 	}
54 
55 	return proto;
56 }
57 
58 static struct sk_buff *ipv6_gso_segment(struct sk_buff *skb,
59 	netdev_features_t features)
60 {
61 	struct sk_buff *segs = ERR_PTR(-EINVAL);
62 	struct ipv6hdr *ipv6h;
63 	const struct net_offload *ops;
64 	int proto;
65 	struct frag_hdr *fptr;
66 	unsigned int unfrag_ip6hlen;
67 	unsigned int payload_len;
68 	u8 *prevhdr;
69 	int offset = 0;
70 	bool encap, udpfrag;
71 	int nhoff;
72 	bool gso_partial;
73 
74 	skb_reset_network_header(skb);
75 	nhoff = skb_network_header(skb) - skb_mac_header(skb);
76 	if (unlikely(!pskb_may_pull(skb, sizeof(*ipv6h))))
77 		goto out;
78 
79 	encap = SKB_GSO_CB(skb)->encap_level > 0;
80 	if (encap)
81 		features &= skb->dev->hw_enc_features;
82 	SKB_GSO_CB(skb)->encap_level += sizeof(*ipv6h);
83 
84 	ipv6h = ipv6_hdr(skb);
85 	__skb_pull(skb, sizeof(*ipv6h));
86 	segs = ERR_PTR(-EPROTONOSUPPORT);
87 
88 	proto = ipv6_gso_pull_exthdrs(skb, ipv6h->nexthdr);
89 
90 	if (skb->encapsulation &&
91 	    skb_shinfo(skb)->gso_type & (SKB_GSO_IPXIP4 | SKB_GSO_IPXIP6))
92 		udpfrag = proto == IPPROTO_UDP && encap;
93 	else
94 		udpfrag = proto == IPPROTO_UDP && !skb->encapsulation;
95 
96 	ops = rcu_dereference(inet6_offloads[proto]);
97 	if (likely(ops && ops->callbacks.gso_segment)) {
98 		skb_reset_transport_header(skb);
99 		segs = ops->callbacks.gso_segment(skb, features);
100 	}
101 
102 	if (IS_ERR_OR_NULL(segs))
103 		goto out;
104 
105 	gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL);
106 
107 	for (skb = segs; skb; skb = skb->next) {
108 		ipv6h = (struct ipv6hdr *)(skb_mac_header(skb) + nhoff);
109 		if (gso_partial)
110 			payload_len = skb_shinfo(skb)->gso_size +
111 				      SKB_GSO_CB(skb)->data_offset +
112 				      skb->head - (unsigned char *)(ipv6h + 1);
113 		else
114 			payload_len = skb->len - nhoff - sizeof(*ipv6h);
115 		ipv6h->payload_len = htons(payload_len);
116 		skb->network_header = (u8 *)ipv6h - skb->head;
117 
118 		if (udpfrag) {
119 			unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr);
120 			fptr = (struct frag_hdr *)((u8 *)ipv6h + unfrag_ip6hlen);
121 			fptr->frag_off = htons(offset);
122 			if (skb->next)
123 				fptr->frag_off |= htons(IP6_MF);
124 			offset += (ntohs(ipv6h->payload_len) -
125 				   sizeof(struct frag_hdr));
126 		}
127 		if (encap)
128 			skb_reset_inner_headers(skb);
129 	}
130 
131 out:
132 	return segs;
133 }
134 
135 /* Return the total length of all the extension hdrs, following the same
136  * logic in ipv6_gso_pull_exthdrs() when parsing ext-hdrs.
137  */
138 static int ipv6_exthdrs_len(struct ipv6hdr *iph,
139 			    const struct net_offload **opps)
140 {
141 	struct ipv6_opt_hdr *opth = (void *)iph;
142 	int len = 0, proto, optlen = sizeof(*iph);
143 
144 	proto = iph->nexthdr;
145 	for (;;) {
146 		if (proto != NEXTHDR_HOP) {
147 			*opps = rcu_dereference(inet6_offloads[proto]);
148 			if (unlikely(!(*opps)))
149 				break;
150 			if (!((*opps)->flags & INET6_PROTO_GSO_EXTHDR))
151 				break;
152 		}
153 		opth = (void *)opth + optlen;
154 		optlen = ipv6_optlen(opth);
155 		len += optlen;
156 		proto = opth->nexthdr;
157 	}
158 	return len;
159 }
160 
161 static struct sk_buff **ipv6_gro_receive(struct sk_buff **head,
162 					 struct sk_buff *skb)
163 {
164 	const struct net_offload *ops;
165 	struct sk_buff **pp = NULL;
166 	struct sk_buff *p;
167 	struct ipv6hdr *iph;
168 	unsigned int nlen;
169 	unsigned int hlen;
170 	unsigned int off;
171 	u16 flush = 1;
172 	int proto;
173 
174 	off = skb_gro_offset(skb);
175 	hlen = off + sizeof(*iph);
176 	iph = skb_gro_header_fast(skb, off);
177 	if (skb_gro_header_hard(skb, hlen)) {
178 		iph = skb_gro_header_slow(skb, hlen, off);
179 		if (unlikely(!iph))
180 			goto out;
181 	}
182 
183 	skb_set_network_header(skb, off);
184 	skb_gro_pull(skb, sizeof(*iph));
185 	skb_set_transport_header(skb, skb_gro_offset(skb));
186 
187 	flush += ntohs(iph->payload_len) != skb_gro_len(skb);
188 
189 	rcu_read_lock();
190 	proto = iph->nexthdr;
191 	ops = rcu_dereference(inet6_offloads[proto]);
192 	if (!ops || !ops->callbacks.gro_receive) {
193 		__pskb_pull(skb, skb_gro_offset(skb));
194 		proto = ipv6_gso_pull_exthdrs(skb, proto);
195 		skb_gro_pull(skb, -skb_transport_offset(skb));
196 		skb_reset_transport_header(skb);
197 		__skb_push(skb, skb_gro_offset(skb));
198 
199 		ops = rcu_dereference(inet6_offloads[proto]);
200 		if (!ops || !ops->callbacks.gro_receive)
201 			goto out_unlock;
202 
203 		iph = ipv6_hdr(skb);
204 	}
205 
206 	NAPI_GRO_CB(skb)->proto = proto;
207 
208 	flush--;
209 	nlen = skb_network_header_len(skb);
210 
211 	for (p = *head; p; p = p->next) {
212 		const struct ipv6hdr *iph2;
213 		__be32 first_word; /* <Version:4><Traffic_Class:8><Flow_Label:20> */
214 
215 		if (!NAPI_GRO_CB(p)->same_flow)
216 			continue;
217 
218 		iph2 = (struct ipv6hdr *)(p->data + off);
219 		first_word = *(__be32 *)iph ^ *(__be32 *)iph2;
220 
221 		/* All fields must match except length and Traffic Class.
222 		 * XXX skbs on the gro_list have all been parsed and pulled
223 		 * already so we don't need to compare nlen
224 		 * (nlen != (sizeof(*iph2) + ipv6_exthdrs_len(iph2, &ops)))
225 		 * memcmp() alone below is suffcient, right?
226 		 */
227 		 if ((first_word & htonl(0xF00FFFFF)) ||
228 		    memcmp(&iph->nexthdr, &iph2->nexthdr,
229 			   nlen - offsetof(struct ipv6hdr, nexthdr))) {
230 			NAPI_GRO_CB(p)->same_flow = 0;
231 			continue;
232 		}
233 		/* flush if Traffic Class fields are different */
234 		NAPI_GRO_CB(p)->flush |= !!(first_word & htonl(0x0FF00000));
235 		NAPI_GRO_CB(p)->flush |= flush;
236 
237 		/* If the previous IP ID value was based on an atomic
238 		 * datagram we can overwrite the value and ignore it.
239 		 */
240 		if (NAPI_GRO_CB(skb)->is_atomic)
241 			NAPI_GRO_CB(p)->flush_id = 0;
242 	}
243 
244 	NAPI_GRO_CB(skb)->is_atomic = true;
245 	NAPI_GRO_CB(skb)->flush |= flush;
246 
247 	skb_gro_postpull_rcsum(skb, iph, nlen);
248 
249 	pp = call_gro_receive(ops->callbacks.gro_receive, head, skb);
250 
251 out_unlock:
252 	rcu_read_unlock();
253 
254 out:
255 	NAPI_GRO_CB(skb)->flush |= flush;
256 
257 	return pp;
258 }
259 
260 static struct sk_buff **sit_ip6ip6_gro_receive(struct sk_buff **head,
261 					       struct sk_buff *skb)
262 {
263 	/* Common GRO receive for SIT and IP6IP6 */
264 
265 	if (NAPI_GRO_CB(skb)->encap_mark) {
266 		NAPI_GRO_CB(skb)->flush = 1;
267 		return NULL;
268 	}
269 
270 	NAPI_GRO_CB(skb)->encap_mark = 1;
271 
272 	return ipv6_gro_receive(head, skb);
273 }
274 
275 static struct sk_buff **ip4ip6_gro_receive(struct sk_buff **head,
276 					   struct sk_buff *skb)
277 {
278 	/* Common GRO receive for SIT and IP6IP6 */
279 
280 	if (NAPI_GRO_CB(skb)->encap_mark) {
281 		NAPI_GRO_CB(skb)->flush = 1;
282 		return NULL;
283 	}
284 
285 	NAPI_GRO_CB(skb)->encap_mark = 1;
286 
287 	return inet_gro_receive(head, skb);
288 }
289 
290 static int ipv6_gro_complete(struct sk_buff *skb, int nhoff)
291 {
292 	const struct net_offload *ops;
293 	struct ipv6hdr *iph = (struct ipv6hdr *)(skb->data + nhoff);
294 	int err = -ENOSYS;
295 
296 	if (skb->encapsulation)
297 		skb_set_inner_network_header(skb, nhoff);
298 
299 	iph->payload_len = htons(skb->len - nhoff - sizeof(*iph));
300 
301 	rcu_read_lock();
302 
303 	nhoff += sizeof(*iph) + ipv6_exthdrs_len(iph, &ops);
304 	if (WARN_ON(!ops || !ops->callbacks.gro_complete))
305 		goto out_unlock;
306 
307 	err = ops->callbacks.gro_complete(skb, nhoff);
308 
309 out_unlock:
310 	rcu_read_unlock();
311 
312 	return err;
313 }
314 
315 static int sit_gro_complete(struct sk_buff *skb, int nhoff)
316 {
317 	skb->encapsulation = 1;
318 	skb_shinfo(skb)->gso_type |= SKB_GSO_IPXIP4;
319 	return ipv6_gro_complete(skb, nhoff);
320 }
321 
322 static int ip6ip6_gro_complete(struct sk_buff *skb, int nhoff)
323 {
324 	skb->encapsulation = 1;
325 	skb_shinfo(skb)->gso_type |= SKB_GSO_IPXIP6;
326 	return ipv6_gro_complete(skb, nhoff);
327 }
328 
329 static int ip4ip6_gro_complete(struct sk_buff *skb, int nhoff)
330 {
331 	skb->encapsulation = 1;
332 	skb_shinfo(skb)->gso_type |= SKB_GSO_IPXIP6;
333 	return inet_gro_complete(skb, nhoff);
334 }
335 
336 static struct packet_offload ipv6_packet_offload __read_mostly = {
337 	.type = cpu_to_be16(ETH_P_IPV6),
338 	.callbacks = {
339 		.gso_segment = ipv6_gso_segment,
340 		.gro_receive = ipv6_gro_receive,
341 		.gro_complete = ipv6_gro_complete,
342 	},
343 };
344 
345 static const struct net_offload sit_offload = {
346 	.callbacks = {
347 		.gso_segment	= ipv6_gso_segment,
348 		.gro_receive    = sit_ip6ip6_gro_receive,
349 		.gro_complete   = sit_gro_complete,
350 	},
351 };
352 
353 static const struct net_offload ip4ip6_offload = {
354 	.callbacks = {
355 		.gso_segment	= inet_gso_segment,
356 		.gro_receive    = ip4ip6_gro_receive,
357 		.gro_complete   = ip4ip6_gro_complete,
358 	},
359 };
360 
361 static const struct net_offload ip6ip6_offload = {
362 	.callbacks = {
363 		.gso_segment	= ipv6_gso_segment,
364 		.gro_receive    = sit_ip6ip6_gro_receive,
365 		.gro_complete   = ip6ip6_gro_complete,
366 	},
367 };
368 static int __init ipv6_offload_init(void)
369 {
370 
371 	if (tcpv6_offload_init() < 0)
372 		pr_crit("%s: Cannot add TCP protocol offload\n", __func__);
373 	if (ipv6_exthdrs_offload_init() < 0)
374 		pr_crit("%s: Cannot add EXTHDRS protocol offload\n", __func__);
375 
376 	dev_add_offload(&ipv6_packet_offload);
377 
378 	inet_add_offload(&sit_offload, IPPROTO_IPV6);
379 	inet6_add_offload(&ip6ip6_offload, IPPROTO_IPV6);
380 	inet6_add_offload(&ip4ip6_offload, IPPROTO_IPIP);
381 
382 	return 0;
383 }
384 
385 fs_initcall(ipv6_offload_init);
386