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
 20#include "ip6_offload.h"
 21
 22static int ipv6_gso_pull_exthdrs(struct sk_buff *skb, int proto)
 23{
 24	const struct net_offload *ops = NULL;
 25
 26	for (;;) {
 27		struct ipv6_opt_hdr *opth;
 28		int len;
 29
 30		if (proto != NEXTHDR_HOP) {
 31			ops = rcu_dereference(inet6_offloads[proto]);
 32
 33			if (unlikely(!ops))
 34				break;
 35
 36			if (!(ops->flags & INET6_PROTO_GSO_EXTHDR))
 37				break;
 38		}
 39
 40		if (unlikely(!pskb_may_pull(skb, 8)))
 41			break;
 42
 43		opth = (void *)skb->data;
 44		len = ipv6_optlen(opth);
 45
 46		if (unlikely(!pskb_may_pull(skb, len)))
 47			break;
 48
 49		opth = (void *)skb->data;
 50		proto = opth->nexthdr;
 51		__skb_pull(skb, len);
 52	}
 53
 54	return proto;
 55}
 56
 57static struct sk_buff *ipv6_gso_segment(struct sk_buff *skb,
 58	netdev_features_t features)
 59{
 60	struct sk_buff *segs = ERR_PTR(-EINVAL);
 61	struct ipv6hdr *ipv6h;
 62	const struct net_offload *ops;
 63	int proto;
 64	struct frag_hdr *fptr;
 65	unsigned int unfrag_ip6hlen;
 66	u8 *prevhdr;
 67	int offset = 0;
 68	bool encap, udpfrag;
 69	int nhoff;
 70
 71	if (unlikely(skb_shinfo(skb)->gso_type &
 72		     ~(SKB_GSO_TCPV4 |
 73		       SKB_GSO_UDP |
 74		       SKB_GSO_DODGY |
 75		       SKB_GSO_TCP_ECN |
 76		       SKB_GSO_GRE |
 77		       SKB_GSO_GRE_CSUM |
 78		       SKB_GSO_IPIP |
 79		       SKB_GSO_SIT |
 80		       SKB_GSO_UDP_TUNNEL |
 81		       SKB_GSO_UDP_TUNNEL_CSUM |
 82		       SKB_GSO_TUNNEL_REMCSUM |
 83		       SKB_GSO_TCPV6 |
 84		       0)))
 85		goto out;
 86
 87	skb_reset_network_header(skb);
 88	nhoff = skb_network_header(skb) - skb_mac_header(skb);
 89	if (unlikely(!pskb_may_pull(skb, sizeof(*ipv6h))))
 90		goto out;
 91
 92	encap = SKB_GSO_CB(skb)->encap_level > 0;
 93	if (encap)
 94		features &= skb->dev->hw_enc_features;
 95	SKB_GSO_CB(skb)->encap_level += sizeof(*ipv6h);
 96
 97	ipv6h = ipv6_hdr(skb);
 98	__skb_pull(skb, sizeof(*ipv6h));
 99	segs = ERR_PTR(-EPROTONOSUPPORT);
100
101	proto = ipv6_gso_pull_exthdrs(skb, ipv6h->nexthdr);
102
103	if (skb->encapsulation &&
104	    skb_shinfo(skb)->gso_type & (SKB_GSO_SIT|SKB_GSO_IPIP))
105		udpfrag = proto == IPPROTO_UDP && encap;
106	else
107		udpfrag = proto == IPPROTO_UDP && !skb->encapsulation;
108
109	ops = rcu_dereference(inet6_offloads[proto]);
110	if (likely(ops && ops->callbacks.gso_segment)) {
111		skb_reset_transport_header(skb);
112		segs = ops->callbacks.gso_segment(skb, features);
113	}
114
115	if (IS_ERR(segs))
116		goto out;
117
118	for (skb = segs; skb; skb = skb->next) {
119		ipv6h = (struct ipv6hdr *)(skb_mac_header(skb) + nhoff);
120		ipv6h->payload_len = htons(skb->len - nhoff - sizeof(*ipv6h));
121		skb->network_header = (u8 *)ipv6h - skb->head;
122
123		if (udpfrag) {
124			unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr);
125			fptr = (struct frag_hdr *)((u8 *)ipv6h + unfrag_ip6hlen);
126			fptr->frag_off = htons(offset);
127			if (skb->next)
128				fptr->frag_off |= htons(IP6_MF);
129			offset += (ntohs(ipv6h->payload_len) -
130				   sizeof(struct frag_hdr));
131		}
132		if (encap)
133			skb_reset_inner_headers(skb);
134	}
135
136out:
137	return segs;
138}
139
140/* Return the total length of all the extension hdrs, following the same
141 * logic in ipv6_gso_pull_exthdrs() when parsing ext-hdrs.
142 */
143static int ipv6_exthdrs_len(struct ipv6hdr *iph,
144			    const struct net_offload **opps)
145{
146	struct ipv6_opt_hdr *opth = (void *)iph;
147	int len = 0, proto, optlen = sizeof(*iph);
148
149	proto = iph->nexthdr;
150	for (;;) {
151		if (proto != NEXTHDR_HOP) {
152			*opps = rcu_dereference(inet6_offloads[proto]);
153			if (unlikely(!(*opps)))
154				break;
155			if (!((*opps)->flags & INET6_PROTO_GSO_EXTHDR))
156				break;
157		}
158		opth = (void *)opth + optlen;
159		optlen = ipv6_optlen(opth);
160		len += optlen;
161		proto = opth->nexthdr;
162	}
163	return len;
164}
165
166static struct sk_buff **ipv6_gro_receive(struct sk_buff **head,
167					 struct sk_buff *skb)
168{
169	const struct net_offload *ops;
170	struct sk_buff **pp = NULL;
171	struct sk_buff *p;
172	struct ipv6hdr *iph;
173	unsigned int nlen;
174	unsigned int hlen;
175	unsigned int off;
176	u16 flush = 1;
177	int proto;
178
179	off = skb_gro_offset(skb);
180	hlen = off + sizeof(*iph);
181	iph = skb_gro_header_fast(skb, off);
182	if (skb_gro_header_hard(skb, hlen)) {
183		iph = skb_gro_header_slow(skb, hlen, off);
184		if (unlikely(!iph))
185			goto out;
186	}
187
188	skb_set_network_header(skb, off);
189	skb_gro_pull(skb, sizeof(*iph));
190	skb_set_transport_header(skb, skb_gro_offset(skb));
191
192	flush += ntohs(iph->payload_len) != skb_gro_len(skb);
193
194	rcu_read_lock();
195	proto = iph->nexthdr;
196	ops = rcu_dereference(inet6_offloads[proto]);
197	if (!ops || !ops->callbacks.gro_receive) {
198		__pskb_pull(skb, skb_gro_offset(skb));
199		proto = ipv6_gso_pull_exthdrs(skb, proto);
200		skb_gro_pull(skb, -skb_transport_offset(skb));
201		skb_reset_transport_header(skb);
202		__skb_push(skb, skb_gro_offset(skb));
203
204		ops = rcu_dereference(inet6_offloads[proto]);
205		if (!ops || !ops->callbacks.gro_receive)
206			goto out_unlock;
207
208		iph = ipv6_hdr(skb);
209	}
210
211	NAPI_GRO_CB(skb)->proto = proto;
212
213	flush--;
214	nlen = skb_network_header_len(skb);
215
216	for (p = *head; p; p = p->next) {
217		const struct ipv6hdr *iph2;
218		__be32 first_word; /* <Version:4><Traffic_Class:8><Flow_Label:20> */
219
220		if (!NAPI_GRO_CB(p)->same_flow)
221			continue;
222
223		iph2 = (struct ipv6hdr *)(p->data + off);
224		first_word = *(__be32 *)iph ^ *(__be32 *)iph2;
225
226		/* All fields must match except length and Traffic Class.
227		 * XXX skbs on the gro_list have all been parsed and pulled
228		 * already so we don't need to compare nlen
229		 * (nlen != (sizeof(*iph2) + ipv6_exthdrs_len(iph2, &ops)))
230		 * memcmp() alone below is suffcient, right?
231		 */
232		 if ((first_word & htonl(0xF00FFFFF)) ||
233		    memcmp(&iph->nexthdr, &iph2->nexthdr,
234			   nlen - offsetof(struct ipv6hdr, nexthdr))) {
235			NAPI_GRO_CB(p)->same_flow = 0;
236			continue;
237		}
238		/* flush if Traffic Class fields are different */
239		NAPI_GRO_CB(p)->flush |= !!(first_word & htonl(0x0FF00000));
240		NAPI_GRO_CB(p)->flush |= flush;
241
242		/* Clear flush_id, there's really no concept of ID in IPv6. */
243		NAPI_GRO_CB(p)->flush_id = 0;
244	}
245
246	NAPI_GRO_CB(skb)->flush |= flush;
247
248	skb_gro_postpull_rcsum(skb, iph, nlen);
249
250	pp = ops->callbacks.gro_receive(head, skb);
251
252out_unlock:
253	rcu_read_unlock();
254
255out:
256	NAPI_GRO_CB(skb)->flush |= flush;
257
258	return pp;
259}
260
261static struct sk_buff **sit_gro_receive(struct sk_buff **head,
262					struct sk_buff *skb)
263{
264	if (NAPI_GRO_CB(skb)->encap_mark) {
265		NAPI_GRO_CB(skb)->flush = 1;
266		return NULL;
267	}
268
269	NAPI_GRO_CB(skb)->encap_mark = 1;
270
271	return ipv6_gro_receive(head, skb);
272}
273
274static int ipv6_gro_complete(struct sk_buff *skb, int nhoff)
275{
276	const struct net_offload *ops;
277	struct ipv6hdr *iph = (struct ipv6hdr *)(skb->data + nhoff);
278	int err = -ENOSYS;
279
280	if (skb->encapsulation)
281		skb_set_inner_network_header(skb, nhoff);
282
283	iph->payload_len = htons(skb->len - nhoff - sizeof(*iph));
284
285	rcu_read_lock();
286
287	nhoff += sizeof(*iph) + ipv6_exthdrs_len(iph, &ops);
288	if (WARN_ON(!ops || !ops->callbacks.gro_complete))
289		goto out_unlock;
290
291	err = ops->callbacks.gro_complete(skb, nhoff);
292
293out_unlock:
294	rcu_read_unlock();
295
296	return err;
297}
298
299static int sit_gro_complete(struct sk_buff *skb, int nhoff)
300{
301	skb->encapsulation = 1;
302	skb_shinfo(skb)->gso_type |= SKB_GSO_SIT;
303	return ipv6_gro_complete(skb, nhoff);
304}
305
306static struct packet_offload ipv6_packet_offload __read_mostly = {
307	.type = cpu_to_be16(ETH_P_IPV6),
308	.callbacks = {
309		.gso_segment = ipv6_gso_segment,
310		.gro_receive = ipv6_gro_receive,
311		.gro_complete = ipv6_gro_complete,
312	},
313};
314
315static const struct net_offload sit_offload = {
316	.callbacks = {
317		.gso_segment	= ipv6_gso_segment,
318		.gro_receive    = sit_gro_receive,
319		.gro_complete   = sit_gro_complete,
320	},
321};
322
323static int __init ipv6_offload_init(void)
324{
325
326	if (tcpv6_offload_init() < 0)
327		pr_crit("%s: Cannot add TCP protocol offload\n", __func__);
328	if (udp_offload_init() < 0)
329		pr_crit("%s: Cannot add UDP protocol offload\n", __func__);
330	if (ipv6_exthdrs_offload_init() < 0)
331		pr_crit("%s: Cannot add EXTHDRS protocol offload\n", __func__);
332
333	dev_add_offload(&ipv6_packet_offload);
334
335	inet_add_offload(&sit_offload, IPPROTO_IPV6);
336
337	return 0;
338}
339
340fs_initcall(ipv6_offload_init);