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v3.15
  1/*
  2 *	IPV4 GSO/GRO offload support
  3 *	Linux INET 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 *	GRE GSO support
 11 */
 12
 13#include <linux/skbuff.h>
 14#include <linux/init.h>
 15#include <net/protocol.h>
 16#include <net/gre.h>
 17
 18static int gre_gso_send_check(struct sk_buff *skb)
 19{
 20	if (!skb->encapsulation)
 21		return -EINVAL;
 22	return 0;
 23}
 24
 25static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
 26				       netdev_features_t features)
 27{
 
 28	struct sk_buff *segs = ERR_PTR(-EINVAL);
 29	netdev_features_t enc_features;
 30	int ghl;
 31	struct gre_base_hdr *greh;
 32	u16 mac_offset = skb->mac_header;
 33	int mac_len = skb->mac_len;
 34	__be16 protocol = skb->protocol;
 35	int tnl_hlen;
 36	bool csum;
 37
 38	if (unlikely(skb_shinfo(skb)->gso_type &
 39				~(SKB_GSO_TCPV4 |
 40				  SKB_GSO_TCPV6 |
 41				  SKB_GSO_UDP |
 42				  SKB_GSO_DODGY |
 43				  SKB_GSO_TCP_ECN |
 44				  SKB_GSO_GRE |
 45				  SKB_GSO_IPIP)))
 46		goto out;
 47
 48	if (unlikely(!pskb_may_pull(skb, sizeof(*greh))))
 49		goto out;
 50
 51	greh = (struct gre_base_hdr *)skb_transport_header(skb);
 52
 53	ghl = skb_inner_network_header(skb) - skb_transport_header(skb);
 54	if (unlikely(ghl < sizeof(*greh)))
 55		goto out;
 56
 57	csum = !!(greh->flags & GRE_CSUM);
 58
 59	if (unlikely(!pskb_may_pull(skb, ghl)))
 60		goto out;
 61
 62	/* setup inner skb. */
 63	skb->protocol = greh->protocol;
 64	skb->encapsulation = 0;
 65
 66	__skb_pull(skb, ghl);
 67	skb_reset_mac_header(skb);
 68	skb_set_network_header(skb, skb_inner_network_offset(skb));
 69	skb->mac_len = skb_inner_network_offset(skb);
 
 
 
 
 
 
 70
 71	/* segment inner packet. */
 72	enc_features = skb->dev->hw_enc_features & netif_skb_features(skb);
 73	segs = skb_mac_gso_segment(skb, enc_features);
 74	if (!segs || IS_ERR(segs)) {
 75		skb_gso_error_unwind(skb, protocol, ghl, mac_offset, mac_len);
 76		goto out;
 77	}
 78
 
 
 
 
 79	skb = segs;
 80	tnl_hlen = skb_tnl_header_len(skb);
 81	do {
 82		__skb_push(skb, ghl);
 83		if (csum) {
 84			__be32 *pcsum;
 85
 86			if (skb_has_shared_frag(skb)) {
 87				int err;
 88
 89				err = __skb_linearize(skb);
 90				if (err) {
 91					kfree_skb_list(segs);
 92					segs = ERR_PTR(err);
 93					goto out;
 94				}
 95			}
 96
 97			greh = (struct gre_base_hdr *)(skb->data);
 98			pcsum = (__be32 *)(greh + 1);
 99			*pcsum = 0;
100			*(__sum16 *)pcsum = csum_fold(skb_checksum(skb, 0, skb->len, 0));
101		}
102		__skb_push(skb, tnl_hlen - ghl);
103
104		skb_reset_inner_headers(skb);
105		skb->encapsulation = 1;
106
 
107		skb_reset_mac_header(skb);
108		skb_set_network_header(skb, mac_len);
109		skb->mac_len = mac_len;
110		skb->protocol = protocol;
111	} while ((skb = skb->next));
112out:
113	return segs;
114}
115
116/* Compute the whole skb csum in s/w and store it, then verify GRO csum
117 * starting from gro_offset.
118 */
119static __sum16 gro_skb_checksum(struct sk_buff *skb)
120{
121	__sum16 sum;
 
 
122
123	skb->csum = skb_checksum(skb, 0, skb->len, 0);
124	NAPI_GRO_CB(skb)->csum = csum_sub(skb->csum,
125		csum_partial(skb->data, skb_gro_offset(skb), 0));
126	sum = csum_fold(NAPI_GRO_CB(skb)->csum);
127	if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE)) {
128		if (unlikely(!sum))
129			netdev_rx_csum_fault(skb->dev);
130	} else
131		skb->ip_summed = CHECKSUM_COMPLETE;
 
 
132
133	return sum;
 
 
 
 
134}
135
136static struct sk_buff **gre_gro_receive(struct sk_buff **head,
137					struct sk_buff *skb)
138{
139	struct sk_buff **pp = NULL;
140	struct sk_buff *p;
141	const struct gre_base_hdr *greh;
142	unsigned int hlen, grehlen;
143	unsigned int off;
144	int flush = 1;
145	struct packet_offload *ptype;
146	__be16 type;
147
 
 
 
 
 
148	off = skb_gro_offset(skb);
149	hlen = off + sizeof(*greh);
150	greh = skb_gro_header_fast(skb, off);
151	if (skb_gro_header_hard(skb, hlen)) {
152		greh = skb_gro_header_slow(skb, hlen, off);
153		if (unlikely(!greh))
154			goto out;
155	}
156
157	/* Only support version 0 and K (key), C (csum) flags. Note that
158	 * although the support for the S (seq#) flag can be added easily
159	 * for GRO, this is problematic for GSO hence can not be enabled
160	 * here because a GRO pkt may end up in the forwarding path, thus
161	 * requiring GSO support to break it up correctly.
162	 */
163	if ((greh->flags & ~(GRE_KEY|GRE_CSUM)) != 0)
164		goto out;
165
 
 
 
 
 
 
 
 
166	type = greh->protocol;
167
168	rcu_read_lock();
169	ptype = gro_find_receive_by_type(type);
170	if (ptype == NULL)
171		goto out_unlock;
172
173	grehlen = GRE_HEADER_SECTION;
174
175	if (greh->flags & GRE_KEY)
176		grehlen += GRE_HEADER_SECTION;
177
178	if (greh->flags & GRE_CSUM)
179		grehlen += GRE_HEADER_SECTION;
180
181	hlen = off + grehlen;
182	if (skb_gro_header_hard(skb, hlen)) {
183		greh = skb_gro_header_slow(skb, hlen, off);
184		if (unlikely(!greh))
185			goto out_unlock;
186	}
187	if (greh->flags & GRE_CSUM) { /* Need to verify GRE csum first */
188		__sum16 csum = 0;
189
190		if (skb->ip_summed == CHECKSUM_COMPLETE)
191			csum = csum_fold(NAPI_GRO_CB(skb)->csum);
192		/* Don't trust csum error calculated/reported by h/w */
193		if (skb->ip_summed == CHECKSUM_NONE || csum != 0)
194			csum = gro_skb_checksum(skb);
195
196		/* GRE CSUM is the 1's complement of the 1's complement sum
197		 * of the GRE hdr plus payload so it should add up to 0xffff
198		 * (and 0 after csum_fold()) just like the IPv4 hdr csum.
199		 */
200		if (csum)
201			goto out_unlock;
 
 
 
202	}
203	flush = 0;
204
205	for (p = *head; p; p = p->next) {
206		const struct gre_base_hdr *greh2;
207
208		if (!NAPI_GRO_CB(p)->same_flow)
209			continue;
210
211		/* The following checks are needed to ensure only pkts
212		 * from the same tunnel are considered for aggregation.
213		 * The criteria for "the same tunnel" includes:
214		 * 1) same version (we only support version 0 here)
215		 * 2) same protocol (we only support ETH_P_IP for now)
216		 * 3) same set of flags
217		 * 4) same key if the key field is present.
218		 */
219		greh2 = (struct gre_base_hdr *)(p->data + off);
220
221		if (greh2->flags != greh->flags ||
222		    greh2->protocol != greh->protocol) {
223			NAPI_GRO_CB(p)->same_flow = 0;
224			continue;
225		}
226		if (greh->flags & GRE_KEY) {
227			/* compare keys */
228			if (*(__be32 *)(greh2+1) != *(__be32 *)(greh+1)) {
229				NAPI_GRO_CB(p)->same_flow = 0;
230				continue;
231			}
232		}
233	}
234
235	skb_gro_pull(skb, grehlen);
236
237	/* Adjusted NAPI_GRO_CB(skb)->csum after skb_gro_pull()*/
238	skb_gro_postpull_rcsum(skb, greh, grehlen);
239
240	pp = ptype->callbacks.gro_receive(head, skb);
 
241
242out_unlock:
243	rcu_read_unlock();
244out:
245	NAPI_GRO_CB(skb)->flush |= flush;
246
247	return pp;
248}
249
250static int gre_gro_complete(struct sk_buff *skb, int nhoff)
251{
252	struct gre_base_hdr *greh = (struct gre_base_hdr *)(skb->data + nhoff);
253	struct packet_offload *ptype;
254	unsigned int grehlen = sizeof(*greh);
255	int err = -ENOENT;
256	__be16 type;
257
 
 
 
258	type = greh->protocol;
259	if (greh->flags & GRE_KEY)
260		grehlen += GRE_HEADER_SECTION;
261
262	if (greh->flags & GRE_CSUM)
263		grehlen += GRE_HEADER_SECTION;
264
265	rcu_read_lock();
266	ptype = gro_find_complete_by_type(type);
267	if (ptype != NULL)
268		err = ptype->callbacks.gro_complete(skb, nhoff + grehlen);
269
270	rcu_read_unlock();
 
 
 
271	return err;
272}
273
274static const struct net_offload gre_offload = {
275	.callbacks = {
276		.gso_send_check = gre_gso_send_check,
277		.gso_segment = gre_gso_segment,
278		.gro_receive = gre_gro_receive,
279		.gro_complete = gre_gro_complete,
280	},
281};
282
283static int __init gre_offload_init(void)
284{
285	return inet_add_offload(&gre_offload, IPPROTO_GRE);
 
 
 
 
 
 
 
 
 
 
 
 
286}
287device_initcall(gre_offload_init);
v4.17
  1/*
  2 *	IPV4 GSO/GRO offload support
  3 *	Linux INET 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 *	GRE GSO support
 11 */
 12
 13#include <linux/skbuff.h>
 14#include <linux/init.h>
 15#include <net/protocol.h>
 16#include <net/gre.h>
 17
 
 
 
 
 
 
 
 18static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
 19				       netdev_features_t features)
 20{
 21	int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
 22	struct sk_buff *segs = ERR_PTR(-EINVAL);
 
 
 
 23	u16 mac_offset = skb->mac_header;
 
 24	__be16 protocol = skb->protocol;
 25	u16 mac_len = skb->mac_len;
 26	int gre_offset, outer_hlen;
 27	bool need_csum, gso_partial;
 
 
 
 
 
 
 
 
 
 28
 29	if (!skb->encapsulation)
 30		goto out;
 31
 32	if (unlikely(tnl_hlen < sizeof(struct gre_base_hdr)))
 
 
 
 33		goto out;
 34
 35	if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
 
 
 36		goto out;
 37
 38	/* setup inner skb. */
 
 39	skb->encapsulation = 0;
 40	SKB_GSO_CB(skb)->encap_level = 0;
 41	__skb_pull(skb, tnl_hlen);
 42	skb_reset_mac_header(skb);
 43	skb_set_network_header(skb, skb_inner_network_offset(skb));
 44	skb->mac_len = skb_inner_network_offset(skb);
 45	skb->protocol = skb->inner_protocol;
 46
 47	need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_GRE_CSUM);
 48	skb->encap_hdr_csum = need_csum;
 49
 50	features &= skb->dev->hw_enc_features;
 51
 52	/* segment inner packet. */
 53	segs = skb_mac_gso_segment(skb, features);
 54	if (IS_ERR_OR_NULL(segs)) {
 55		skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset,
 56				     mac_len);
 57		goto out;
 58	}
 59
 60	gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL);
 61
 62	outer_hlen = skb_tnl_header_len(skb);
 63	gre_offset = outer_hlen - tnl_hlen;
 64	skb = segs;
 
 65	do {
 66		struct gre_base_hdr *greh;
 67		__sum16 *pcsum;
 
 
 
 
 
 
 
 
 
 
 
 
 68
 69		/* Set up inner headers if we are offloading inner checksum */
 70		if (skb->ip_summed == CHECKSUM_PARTIAL) {
 71			skb_reset_inner_headers(skb);
 72			skb->encapsulation = 1;
 73		}
 
 74
 75		skb->mac_len = mac_len;
 76		skb->protocol = protocol;
 77
 78		__skb_push(skb, outer_hlen);
 79		skb_reset_mac_header(skb);
 80		skb_set_network_header(skb, mac_len);
 81		skb_set_transport_header(skb, gre_offset);
 
 
 
 
 
 82
 83		if (!need_csum)
 84			continue;
 85
 86		greh = (struct gre_base_hdr *)skb_transport_header(skb);
 87		pcsum = (__sum16 *)(greh + 1);
 88
 89		if (gso_partial && skb_is_gso(skb)) {
 90			unsigned int partial_adj;
 91
 92			/* Adjust checksum to account for the fact that
 93			 * the partial checksum is based on actual size
 94			 * whereas headers should be based on MSS size.
 95			 */
 96			partial_adj = skb->len + skb_headroom(skb) -
 97				      SKB_GSO_CB(skb)->data_offset -
 98				      skb_shinfo(skb)->gso_size;
 99			*pcsum = ~csum_fold((__force __wsum)htonl(partial_adj));
100		} else {
101			*pcsum = 0;
102		}
103
104		*(pcsum + 1) = 0;
105		*pcsum = gso_make_checksum(skb, 0);
106	} while ((skb = skb->next));
107out:
108	return segs;
109}
110
111static struct sk_buff **gre_gro_receive(struct sk_buff **head,
112					struct sk_buff *skb)
113{
114	struct sk_buff **pp = NULL;
115	struct sk_buff *p;
116	const struct gre_base_hdr *greh;
117	unsigned int hlen, grehlen;
118	unsigned int off;
119	int flush = 1;
120	struct packet_offload *ptype;
121	__be16 type;
122
123	if (NAPI_GRO_CB(skb)->encap_mark)
124		goto out;
125
126	NAPI_GRO_CB(skb)->encap_mark = 1;
127
128	off = skb_gro_offset(skb);
129	hlen = off + sizeof(*greh);
130	greh = skb_gro_header_fast(skb, off);
131	if (skb_gro_header_hard(skb, hlen)) {
132		greh = skb_gro_header_slow(skb, hlen, off);
133		if (unlikely(!greh))
134			goto out;
135	}
136
137	/* Only support version 0 and K (key), C (csum) flags. Note that
138	 * although the support for the S (seq#) flag can be added easily
139	 * for GRO, this is problematic for GSO hence can not be enabled
140	 * here because a GRO pkt may end up in the forwarding path, thus
141	 * requiring GSO support to break it up correctly.
142	 */
143	if ((greh->flags & ~(GRE_KEY|GRE_CSUM)) != 0)
144		goto out;
145
146	/* We can only support GRE_CSUM if we can track the location of
147	 * the GRE header.  In the case of FOU/GUE we cannot because the
148	 * outer UDP header displaces the GRE header leaving us in a state
149	 * of limbo.
150	 */
151	if ((greh->flags & GRE_CSUM) && NAPI_GRO_CB(skb)->is_fou)
152		goto out;
153
154	type = greh->protocol;
155
156	rcu_read_lock();
157	ptype = gro_find_receive_by_type(type);
158	if (!ptype)
159		goto out_unlock;
160
161	grehlen = GRE_HEADER_SECTION;
162
163	if (greh->flags & GRE_KEY)
164		grehlen += GRE_HEADER_SECTION;
165
166	if (greh->flags & GRE_CSUM)
167		grehlen += GRE_HEADER_SECTION;
168
169	hlen = off + grehlen;
170	if (skb_gro_header_hard(skb, hlen)) {
171		greh = skb_gro_header_slow(skb, hlen, off);
172		if (unlikely(!greh))
173			goto out_unlock;
174	}
 
 
175
176	/* Don't bother verifying checksum if we're going to flush anyway. */
177	if ((greh->flags & GRE_CSUM) && !NAPI_GRO_CB(skb)->flush) {
178		if (skb_gro_checksum_simple_validate(skb))
 
 
 
 
 
 
 
 
179			goto out_unlock;
180
181		skb_gro_checksum_try_convert(skb, IPPROTO_GRE, 0,
182					     null_compute_pseudo);
183	}
 
184
185	for (p = *head; p; p = p->next) {
186		const struct gre_base_hdr *greh2;
187
188		if (!NAPI_GRO_CB(p)->same_flow)
189			continue;
190
191		/* The following checks are needed to ensure only pkts
192		 * from the same tunnel are considered for aggregation.
193		 * The criteria for "the same tunnel" includes:
194		 * 1) same version (we only support version 0 here)
195		 * 2) same protocol (we only support ETH_P_IP for now)
196		 * 3) same set of flags
197		 * 4) same key if the key field is present.
198		 */
199		greh2 = (struct gre_base_hdr *)(p->data + off);
200
201		if (greh2->flags != greh->flags ||
202		    greh2->protocol != greh->protocol) {
203			NAPI_GRO_CB(p)->same_flow = 0;
204			continue;
205		}
206		if (greh->flags & GRE_KEY) {
207			/* compare keys */
208			if (*(__be32 *)(greh2+1) != *(__be32 *)(greh+1)) {
209				NAPI_GRO_CB(p)->same_flow = 0;
210				continue;
211			}
212		}
213	}
214
215	skb_gro_pull(skb, grehlen);
216
217	/* Adjusted NAPI_GRO_CB(skb)->csum after skb_gro_pull()*/
218	skb_gro_postpull_rcsum(skb, greh, grehlen);
219
220	pp = call_gro_receive(ptype->callbacks.gro_receive, head, skb);
221	flush = 0;
222
223out_unlock:
224	rcu_read_unlock();
225out:
226	NAPI_GRO_CB(skb)->flush |= flush;
227
228	return pp;
229}
230
231static int gre_gro_complete(struct sk_buff *skb, int nhoff)
232{
233	struct gre_base_hdr *greh = (struct gre_base_hdr *)(skb->data + nhoff);
234	struct packet_offload *ptype;
235	unsigned int grehlen = sizeof(*greh);
236	int err = -ENOENT;
237	__be16 type;
238
239	skb->encapsulation = 1;
240	skb_shinfo(skb)->gso_type = SKB_GSO_GRE;
241
242	type = greh->protocol;
243	if (greh->flags & GRE_KEY)
244		grehlen += GRE_HEADER_SECTION;
245
246	if (greh->flags & GRE_CSUM)
247		grehlen += GRE_HEADER_SECTION;
248
249	rcu_read_lock();
250	ptype = gro_find_complete_by_type(type);
251	if (ptype)
252		err = ptype->callbacks.gro_complete(skb, nhoff + grehlen);
253
254	rcu_read_unlock();
255
256	skb_set_inner_mac_header(skb, nhoff + grehlen);
257
258	return err;
259}
260
261static const struct net_offload gre_offload = {
262	.callbacks = {
 
263		.gso_segment = gre_gso_segment,
264		.gro_receive = gre_gro_receive,
265		.gro_complete = gre_gro_complete,
266	},
267};
268
269static int __init gre_offload_init(void)
270{
271	int err;
272
273	err = inet_add_offload(&gre_offload, IPPROTO_GRE);
274#if IS_ENABLED(CONFIG_IPV6)
275	if (err)
276		return err;
277
278	err = inet6_add_offload(&gre_offload, IPPROTO_GRE);
279	if (err)
280		inet_del_offload(&gre_offload, IPPROTO_GRE);
281#endif
282
283	return err;
284}
285device_initcall(gre_offload_init);