2 * IPV4 GSO/GRO offload support
3 * Linux INET implementation
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.
13 #include <linux/skbuff.h>
14 #include <linux/init.h>
15 #include <net/protocol.h>
18 static int gre_gso_send_check(struct sk_buff *skb)
20 if (!skb->encapsulation)
25 static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
26 netdev_features_t features)
28 struct sk_buff *segs = ERR_PTR(-EINVAL);
29 netdev_features_t enc_features;
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;
38 if (unlikely(skb_shinfo(skb)->gso_type &
49 if (unlikely(!pskb_may_pull(skb, sizeof(*greh))))
52 greh = (struct gre_base_hdr *)skb_transport_header(skb);
54 ghl = skb_inner_network_header(skb) - skb_transport_header(skb);
55 if (unlikely(ghl < sizeof(*greh)))
58 csum = !!(greh->flags & GRE_CSUM);
60 skb->encap_hdr_csum = 1;
62 if (unlikely(!pskb_may_pull(skb, ghl)))
65 /* setup inner skb. */
66 skb->protocol = greh->protocol;
67 skb->encapsulation = 0;
70 skb_reset_mac_header(skb);
71 skb_set_network_header(skb, skb_inner_network_offset(skb));
72 skb->mac_len = skb_inner_network_offset(skb);
74 /* segment inner packet. */
75 enc_features = skb->dev->hw_enc_features & netif_skb_features(skb);
76 segs = skb_mac_gso_segment(skb, enc_features);
77 if (IS_ERR_OR_NULL(segs)) {
78 skb_gso_error_unwind(skb, protocol, ghl, mac_offset, mac_len);
83 tnl_hlen = skb_tnl_header_len(skb);
89 if (skb_has_shared_frag(skb)) {
92 err = __skb_linearize(skb);
100 skb_reset_transport_header(skb);
102 greh = (struct gre_base_hdr *)
103 skb_transport_header(skb);
104 pcsum = (__be32 *)(greh + 1);
106 *(__sum16 *)pcsum = gso_make_checksum(skb, 0);
108 __skb_push(skb, tnl_hlen - ghl);
110 skb_reset_inner_headers(skb);
111 skb->encapsulation = 1;
113 skb_reset_mac_header(skb);
114 skb_set_network_header(skb, mac_len);
115 skb->mac_len = mac_len;
116 skb->protocol = protocol;
117 } while ((skb = skb->next));
122 static struct sk_buff **gre_gro_receive(struct sk_buff **head,
125 struct sk_buff **pp = NULL;
127 const struct gre_base_hdr *greh;
128 unsigned int hlen, grehlen;
131 struct packet_offload *ptype;
134 off = skb_gro_offset(skb);
135 hlen = off + sizeof(*greh);
136 greh = skb_gro_header_fast(skb, off);
137 if (skb_gro_header_hard(skb, hlen)) {
138 greh = skb_gro_header_slow(skb, hlen, off);
143 /* Only support version 0 and K (key), C (csum) flags. Note that
144 * although the support for the S (seq#) flag can be added easily
145 * for GRO, this is problematic for GSO hence can not be enabled
146 * here because a GRO pkt may end up in the forwarding path, thus
147 * requiring GSO support to break it up correctly.
149 if ((greh->flags & ~(GRE_KEY|GRE_CSUM)) != 0)
152 type = greh->protocol;
155 ptype = gro_find_receive_by_type(type);
159 grehlen = GRE_HEADER_SECTION;
161 if (greh->flags & GRE_KEY)
162 grehlen += GRE_HEADER_SECTION;
164 if (greh->flags & GRE_CSUM)
165 grehlen += GRE_HEADER_SECTION;
167 hlen = off + grehlen;
168 if (skb_gro_header_hard(skb, hlen)) {
169 greh = skb_gro_header_slow(skb, hlen, off);
174 /* Don't bother verifying checksum if we're going to flush anyway. */
175 if ((greh->flags & GRE_CSUM) && !NAPI_GRO_CB(skb)->flush) {
176 if (skb_gro_checksum_simple_validate(skb))
179 skb_gro_checksum_try_convert(skb, IPPROTO_GRE, 0,
180 null_compute_pseudo);
185 for (p = *head; p; p = p->next) {
186 const struct gre_base_hdr *greh2;
188 if (!NAPI_GRO_CB(p)->same_flow)
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.
199 greh2 = (struct gre_base_hdr *)(p->data + off);
201 if (greh2->flags != greh->flags ||
202 greh2->protocol != greh->protocol) {
203 NAPI_GRO_CB(p)->same_flow = 0;
206 if (greh->flags & GRE_KEY) {
208 if (*(__be32 *)(greh2+1) != *(__be32 *)(greh+1)) {
209 NAPI_GRO_CB(p)->same_flow = 0;
215 skb_gro_pull(skb, grehlen);
217 /* Adjusted NAPI_GRO_CB(skb)->csum after skb_gro_pull()*/
218 skb_gro_postpull_rcsum(skb, greh, grehlen);
220 pp = ptype->callbacks.gro_receive(head, skb);
225 NAPI_GRO_CB(skb)->flush |= flush;
230 static int gre_gro_complete(struct sk_buff *skb, int nhoff)
232 struct gre_base_hdr *greh = (struct gre_base_hdr *)(skb->data + nhoff);
233 struct packet_offload *ptype;
234 unsigned int grehlen = sizeof(*greh);
238 skb->encapsulation = 1;
239 skb_shinfo(skb)->gso_type = SKB_GSO_GRE;
241 type = greh->protocol;
242 if (greh->flags & GRE_KEY)
243 grehlen += GRE_HEADER_SECTION;
245 if (greh->flags & GRE_CSUM)
246 grehlen += GRE_HEADER_SECTION;
249 ptype = gro_find_complete_by_type(type);
251 err = ptype->callbacks.gro_complete(skb, nhoff + grehlen);
257 static const struct net_offload gre_offload = {
259 .gso_send_check = gre_gso_send_check,
260 .gso_segment = gre_gso_segment,
261 .gro_receive = gre_gro_receive,
262 .gro_complete = gre_gro_complete,
266 static int __init gre_offload_init(void)
268 return inet_add_offload(&gre_offload, IPPROTO_GRE);
270 device_initcall(gre_offload_init);