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 struct sk_buff *gre_gso_segment(struct sk_buff *skb,
19 netdev_features_t features)
21 struct sk_buff *segs = ERR_PTR(-EINVAL);
22 netdev_features_t enc_features;
24 struct gre_base_hdr *greh;
25 u16 mac_offset = skb->mac_header;
26 int mac_len = skb->mac_len;
27 __be16 protocol = skb->protocol;
31 if (unlikely(skb_shinfo(skb)->gso_type &
43 if (!skb->encapsulation)
46 if (unlikely(!pskb_may_pull(skb, sizeof(*greh))))
49 greh = (struct gre_base_hdr *)skb_transport_header(skb);
51 ghl = skb_inner_mac_header(skb) - skb_transport_header(skb);
52 if (unlikely(ghl < sizeof(*greh)))
55 csum = !!(greh->flags & GRE_CSUM);
57 skb->encap_hdr_csum = 1;
59 /* setup inner skb. */
60 skb->protocol = greh->protocol;
61 skb->encapsulation = 0;
63 if (unlikely(!pskb_may_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);
71 /* segment inner packet. */
72 enc_features = skb->dev->hw_enc_features & features;
73 segs = skb_mac_gso_segment(skb, enc_features);
74 if (IS_ERR_OR_NULL(segs)) {
75 skb_gso_error_unwind(skb, protocol, ghl, mac_offset, mac_len);
80 tnl_hlen = skb_tnl_header_len(skb);
86 if (skb_has_shared_frag(skb)) {
89 err = __skb_linearize(skb);
97 skb_reset_transport_header(skb);
99 greh = (struct gre_base_hdr *)
100 skb_transport_header(skb);
101 pcsum = (__be32 *)(greh + 1);
103 *(__sum16 *)pcsum = gso_make_checksum(skb, 0);
105 __skb_push(skb, tnl_hlen - ghl);
107 skb_reset_inner_headers(skb);
108 skb->encapsulation = 1;
110 skb_reset_mac_header(skb);
111 skb_set_network_header(skb, mac_len);
112 skb->mac_len = mac_len;
113 skb->protocol = protocol;
114 } while ((skb = skb->next));
119 static struct sk_buff **gre_gro_receive(struct sk_buff **head,
122 struct sk_buff **pp = NULL;
124 const struct gre_base_hdr *greh;
125 unsigned int hlen, grehlen;
128 struct packet_offload *ptype;
131 if (NAPI_GRO_CB(skb)->encap_mark)
134 NAPI_GRO_CB(skb)->encap_mark = 1;
136 off = skb_gro_offset(skb);
137 hlen = off + sizeof(*greh);
138 greh = skb_gro_header_fast(skb, off);
139 if (skb_gro_header_hard(skb, hlen)) {
140 greh = skb_gro_header_slow(skb, hlen, off);
145 /* Only support version 0 and K (key), C (csum) flags. Note that
146 * although the support for the S (seq#) flag can be added easily
147 * for GRO, this is problematic for GSO hence can not be enabled
148 * here because a GRO pkt may end up in the forwarding path, thus
149 * requiring GSO support to break it up correctly.
151 if ((greh->flags & ~(GRE_KEY|GRE_CSUM)) != 0)
154 /* We can only support GRE_CSUM if we can track the location of
155 * the GRE header. In the case of FOU/GUE we cannot because the
156 * outer UDP header displaces the GRE header leaving us in a state
159 if ((greh->flags & GRE_CSUM) && NAPI_GRO_CB(skb)->is_fou)
162 type = greh->protocol;
165 ptype = gro_find_receive_by_type(type);
169 grehlen = GRE_HEADER_SECTION;
171 if (greh->flags & GRE_KEY)
172 grehlen += GRE_HEADER_SECTION;
174 if (greh->flags & GRE_CSUM)
175 grehlen += GRE_HEADER_SECTION;
177 hlen = off + grehlen;
178 if (skb_gro_header_hard(skb, hlen)) {
179 greh = skb_gro_header_slow(skb, hlen, off);
184 /* Don't bother verifying checksum if we're going to flush anyway. */
185 if ((greh->flags & GRE_CSUM) && !NAPI_GRO_CB(skb)->flush) {
186 if (skb_gro_checksum_simple_validate(skb))
189 skb_gro_checksum_try_convert(skb, IPPROTO_GRE, 0,
190 null_compute_pseudo);
195 for (p = *head; p; p = p->next) {
196 const struct gre_base_hdr *greh2;
198 if (!NAPI_GRO_CB(p)->same_flow)
201 /* The following checks are needed to ensure only pkts
202 * from the same tunnel are considered for aggregation.
203 * The criteria for "the same tunnel" includes:
204 * 1) same version (we only support version 0 here)
205 * 2) same protocol (we only support ETH_P_IP for now)
206 * 3) same set of flags
207 * 4) same key if the key field is present.
209 greh2 = (struct gre_base_hdr *)(p->data + off);
211 if (greh2->flags != greh->flags ||
212 greh2->protocol != greh->protocol) {
213 NAPI_GRO_CB(p)->same_flow = 0;
216 if (greh->flags & GRE_KEY) {
218 if (*(__be32 *)(greh2+1) != *(__be32 *)(greh+1)) {
219 NAPI_GRO_CB(p)->same_flow = 0;
225 skb_gro_pull(skb, grehlen);
227 /* Adjusted NAPI_GRO_CB(skb)->csum after skb_gro_pull()*/
228 skb_gro_postpull_rcsum(skb, greh, grehlen);
230 pp = call_gro_receive(ptype->callbacks.gro_receive, head, skb);
235 NAPI_GRO_CB(skb)->flush |= flush;
240 static int gre_gro_complete(struct sk_buff *skb, int nhoff)
242 struct gre_base_hdr *greh = (struct gre_base_hdr *)(skb->data + nhoff);
243 struct packet_offload *ptype;
244 unsigned int grehlen = sizeof(*greh);
248 skb->encapsulation = 1;
249 skb_shinfo(skb)->gso_type = SKB_GSO_GRE;
251 type = greh->protocol;
252 if (greh->flags & GRE_KEY)
253 grehlen += GRE_HEADER_SECTION;
255 if (greh->flags & GRE_CSUM)
256 grehlen += GRE_HEADER_SECTION;
259 ptype = gro_find_complete_by_type(type);
261 err = ptype->callbacks.gro_complete(skb, nhoff + grehlen);
265 skb_set_inner_mac_header(skb, nhoff + grehlen);
270 static const struct net_offload gre_offload = {
272 .gso_segment = gre_gso_segment,
273 .gro_receive = gre_gro_receive,
274 .gro_complete = gre_gro_complete,
278 static int __init gre_offload_init(void)
280 return inet_add_offload(&gre_offload, IPPROTO_GRE);
282 device_initcall(gre_offload_init);