aboutsummaryrefslogtreecommitdiff
path: root/net/ipv4/gre_offload.c
blob: b9673c21be452f0cf1f1824187252a38f83bbaf0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
/*
 *	IPV4 GSO/GRO offload support
 *	Linux INET implementation
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License
 *	as published by the Free Software Foundation; either version
 *	2 of the License, or (at your option) any later version.
 *
 *	GRE GSO support
 */

#include <linux/skbuff.h>
#include <linux/init.h>
#include <net/protocol.h>
#include <net/gre.h>

static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
				       netdev_features_t features)
{
	int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
	struct sk_buff *segs = ERR_PTR(-EINVAL);
	u16 mac_offset = skb->mac_header;
	__be16 protocol = skb->protocol;
	u16 mac_len = skb->mac_len;
	int gre_offset, outer_hlen;
	bool need_csum, gso_partial;

	if (!skb->encapsulation)
		goto out;

	if (unlikely(tnl_hlen < sizeof(struct gre_base_hdr)))
		goto out;

	if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
		goto out;

	/* setup inner skb. */
	skb->encapsulation = 0;
	SKB_GSO_CB(skb)->encap_level = 0;
	__skb_pull(skb, tnl_hlen);
	skb_reset_mac_header(skb);
	skb_set_network_header(skb, skb_inner_network_offset(skb));
	skb->mac_len = skb_inner_network_offset(skb);
	skb->protocol = skb->inner_protocol;

	need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_GRE_CSUM);
	skb->encap_hdr_csum = need_csum;

	features &= skb->dev->hw_enc_features;

	/* segment inner packet. */
	segs = skb_mac_gso_segment(skb, features);
	if (IS_ERR_OR_NULL(segs)) {
		skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset,
				     mac_len);
		goto out;
	}

	gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL);

	outer_hlen = skb_tnl_header_len(skb);
	gre_offset = outer_hlen - tnl_hlen;
	skb = segs;
	do {
		struct gre_base_hdr *greh;
		__sum16 *pcsum;

		/* Set up inner headers if we are offloading inner checksum */
		if (skb->ip_summed == CHECKSUM_PARTIAL) {
			skb_reset_inner_headers(skb);
			skb->encapsulation = 1;
		}

		skb->mac_len = mac_len;
		skb->protocol = protocol;

		__skb_push(skb, outer_hlen);
		skb_reset_mac_header(skb);
		skb_set_network_header(skb, mac_len);
		skb_set_transport_header(skb, gre_offset);

		if (!need_csum)
			continue;

		greh = (struct gre_base_hdr *)skb_transport_header(skb);
		pcsum = (__sum16 *)(greh + 1);

		if (gso_partial && skb_is_gso(skb)) {
			unsigned int partial_adj;

			/* Adjust checksum to account for the fact that
			 * the partial checksum is based on actual size
			 * whereas headers should be based on MSS size.
			 */
			partial_adj = skb->len + skb_headroom(skb) -
				      SKB_GSO_CB(skb)->data_offset -
				      skb_shinfo(skb)->gso_size;
			*pcsum = ~csum_fold((__force __wsum)htonl(partial_adj));
		} else {
			*pcsum = 0;
		}

		*(pcsum + 1) = 0;
		*pcsum = gso_make_checksum(skb, 0);
	} while ((skb = skb->next));
out:
	return segs;
}

static struct sk_buff *gre_gro_receive(struct list_head *head,
				       struct sk_buff *skb)
{
	struct sk_buff *pp = NULL;
	struct sk_buff *p;
	const struct gre_base_hdr *greh;
	unsigned int hlen, grehlen;
	unsigned int off;
	int flush = 1;
	struct packet_offload *ptype;
	__be16 type;

	if (NAPI_GRO_CB(skb)->encap_mark)
		goto out;

	NAPI_GRO_CB(skb)->encap_mark = 1;

	off = skb_gro_offset(skb);
	hlen = off + sizeof(*greh);
	greh = skb_gro_header_fast(skb, off);
	if (skb_gro_header_hard(skb, hlen)) {
		greh = skb_gro_header_slow(skb, hlen, off);
		if (unlikely(!greh))
			goto out;
	}

	/* Only support version 0 and K (key), C (csum) flags. Note that
	 * although the support for the S (seq#) flag can be added easily
	 * for GRO, this is problematic for GSO hence can not be enabled
	 * here because a GRO pkt may end up in the forwarding path, thus
	 * requiring GSO support to break it up correctly.
	 */
	if ((greh->flags & ~(GRE_KEY|GRE_CSUM)) != 0)
		goto out;

	/* We can only support GRE_CSUM if we can track the location of
	 * the GRE header.  In the case of FOU/GUE we cannot because the
	 * outer UDP header displaces the GRE header leaving us in a state
	 * of limbo.
	 */
	if ((greh->flags & GRE_CSUM) && NAPI_GRO_CB(skb)->is_fou)
		goto out;

	type = greh->protocol;

	rcu_read_lock();
	ptype = gro_find_receive_by_type(type);
	if (!ptype)
		goto out_unlock;

	grehlen = GRE_HEADER_SECTION;

	if (greh->flags & GRE_KEY)
		grehlen += GRE_HEADER_SECTION;

	if (greh->flags & GRE_CSUM)
		grehlen += GRE_HEADER_SECTION;

	hlen = off + grehlen;
	if (skb_gro_header_hard(skb, hlen)) {
		greh = skb_gro_header_slow(skb, hlen, off);
		if (unlikely(!greh))
			goto out_unlock;
	}

	/* Don't bother verifying checksum if we're going to flush anyway. */
	if ((greh->flags & GRE_CSUM) && !NAPI_GRO_CB(skb)->flush) {
		if (skb_gro_checksum_simple_validate(skb))
			goto out_unlock;

		skb_gro_checksum_try_convert(skb, IPPROTO_GRE, 0,
					     null_compute_pseudo);
	}

	list_for_each_entry(p, head, list) {
		const struct gre_base_hdr *greh2;

		if (!NAPI_GRO_CB(p)->same_flow)
			continue;

		/* The following checks are needed to ensure only pkts
		 * from the same tunnel are considered for aggregation.
		 * The criteria for "the same tunnel" includes:
		 * 1) same version (we only support version 0 here)
		 * 2) same protocol (we only support ETH_P_IP for now)
		 * 3) same set of flags
		 * 4) same key if the key field is present.
		 */
		greh2 = (struct gre_base_hdr *)(p->data + off);

		if (greh2->flags != greh->flags ||
		    greh2->protocol != greh->protocol) {
			NAPI_GRO_CB(p)->same_flow = 0;
			continue;
		}
		if (greh->flags & GRE_KEY) {
			/* compare keys */
			if (*(__be32 *)(greh2+1) != *(__be32 *)(greh+1)) {
				NAPI_GRO_CB(p)->same_flow = 0;
				continue;
			}
		}
	}

	skb_gro_pull(skb, grehlen);

	/* Adjusted NAPI_GRO_CB(skb)->csum after skb_gro_pull()*/
	skb_gro_postpull_rcsum(skb, greh, grehlen);

	pp = call_gro_receive(ptype->callbacks.gro_receive, head, skb);
	flush = 0;

out_unlock:
	rcu_read_unlock();
out:
	NAPI_GRO_CB(skb)->flush |= flush;

	return pp;
}

static int gre_gro_complete(struct sk_buff *skb, int nhoff)
{
	struct gre_base_hdr *greh = (struct gre_base_hdr *)(skb->data + nhoff);
	struct packet_offload *ptype;
	unsigned int grehlen = sizeof(*greh);
	int err = -ENOENT;
	__be16 type;

	skb->encapsulation = 1;
	skb_shinfo(skb)->gso_type = SKB_GSO_GRE;

	type = greh->protocol;
	if (greh->flags & GRE_KEY)
		grehlen += GRE_HEADER_SECTION;

	if (greh->flags & GRE_CSUM)
		grehlen += GRE_HEADER_SECTION;

	rcu_read_lock();
	ptype = gro_find_complete_by_type(type);
	if (ptype)
		err = ptype->callbacks.gro_complete(skb, nhoff + grehlen);

	rcu_read_unlock();

	skb_set_inner_mac_header(skb, nhoff + grehlen);

	return err;
}

static const struct net_offload gre_offload = {
	.callbacks = {
		.gso_segment = gre_gso_segment,
		.gro_receive = gre_gro_receive,
		.gro_complete = gre_gro_complete,
	},
};

static int __init gre_offload_init(void)
{
	int err;

	err = inet_add_offload(&gre_offload, IPPROTO_GRE);
#if IS_ENABLED(CONFIG_IPV6)
	if (err)
		return err;

	err = inet6_add_offload(&gre_offload, IPPROTO_GRE);
	if (err)
		inet_del_offload(&gre_offload, IPPROTO_GRE);
#endif

	return err;
}
device_initcall(gre_offload_init);