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 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;
29 if (unlikely(skb_shinfo(skb)->gso_type &
42 if (!skb->encapsulation)
45 if (unlikely(tnl_hlen < sizeof(struct gre_base_hdr)))
48 if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
51 /* setup inner skb. */
52 skb->encapsulation = 0;
53 SKB_GSO_CB(skb)->encap_level = 0;
54 __skb_pull(skb, tnl_hlen);
55 skb_reset_mac_header(skb);
56 skb_set_network_header(skb, skb_inner_network_offset(skb));
57 skb->mac_len = skb_inner_network_offset(skb);
58 skb->protocol = skb->inner_protocol;
60 need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_GRE_CSUM);
61 skb->encap_hdr_csum = need_csum;
63 ufo = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP);
65 features &= skb->dev->hw_enc_features;
67 /* The only checksum offload we care about from here on out is the
68 * outer one so strip the existing checksum feature flags based
69 * on the fact that we will be computing our checksum in software.
72 features &= ~NETIF_F_CSUM_MASK;
74 features |= NETIF_F_HW_CSUM;
77 /* segment inner packet. */
78 segs = skb_mac_gso_segment(skb, features);
79 if (IS_ERR_OR_NULL(segs)) {
80 skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset,
85 outer_hlen = skb_tnl_header_len(skb);
86 gre_offset = outer_hlen - tnl_hlen;
89 struct gre_base_hdr *greh;
92 /* Set up inner headers if we are offloading inner checksum */
93 if (skb->ip_summed == CHECKSUM_PARTIAL) {
94 skb_reset_inner_headers(skb);
95 skb->encapsulation = 1;
98 skb->mac_len = mac_len;
99 skb->protocol = protocol;
101 __skb_push(skb, outer_hlen);
102 skb_reset_mac_header(skb);
103 skb_set_network_header(skb, mac_len);
104 skb_set_transport_header(skb, gre_offset);
109 greh = (struct gre_base_hdr *)skb_transport_header(skb);
110 pcsum = (__be32 *)(greh + 1);
113 *(__sum16 *)pcsum = gso_make_checksum(skb, 0);
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);
193 for (p = *head; p; p = p->next) {
194 const struct gre_base_hdr *greh2;
196 if (!NAPI_GRO_CB(p)->same_flow)
199 /* The following checks are needed to ensure only pkts
200 * from the same tunnel are considered for aggregation.
201 * The criteria for "the same tunnel" includes:
202 * 1) same version (we only support version 0 here)
203 * 2) same protocol (we only support ETH_P_IP for now)
204 * 3) same set of flags
205 * 4) same key if the key field is present.
207 greh2 = (struct gre_base_hdr *)(p->data + off);
209 if (greh2->flags != greh->flags ||
210 greh2->protocol != greh->protocol) {
211 NAPI_GRO_CB(p)->same_flow = 0;
214 if (greh->flags & GRE_KEY) {
216 if (*(__be32 *)(greh2+1) != *(__be32 *)(greh+1)) {
217 NAPI_GRO_CB(p)->same_flow = 0;
223 skb_gro_pull(skb, grehlen);
225 /* Adjusted NAPI_GRO_CB(skb)->csum after skb_gro_pull()*/
226 skb_gro_postpull_rcsum(skb, greh, grehlen);
228 pp = ptype->callbacks.gro_receive(head, skb);
234 NAPI_GRO_CB(skb)->flush |= flush;
239 static int gre_gro_complete(struct sk_buff *skb, int nhoff)
241 struct gre_base_hdr *greh = (struct gre_base_hdr *)(skb->data + nhoff);
242 struct packet_offload *ptype;
243 unsigned int grehlen = sizeof(*greh);
247 skb->encapsulation = 1;
248 skb_shinfo(skb)->gso_type = SKB_GSO_GRE;
250 type = greh->protocol;
251 if (greh->flags & GRE_KEY)
252 grehlen += GRE_HEADER_SECTION;
254 if (greh->flags & GRE_CSUM)
255 grehlen += GRE_HEADER_SECTION;
258 ptype = gro_find_complete_by_type(type);
260 err = ptype->callbacks.gro_complete(skb, nhoff + grehlen);
264 skb_set_inner_mac_header(skb, nhoff + grehlen);
269 static const struct net_offload gre_offload = {
271 .gso_segment = gre_gso_segment,
272 .gro_receive = gre_gro_receive,
273 .gro_complete = gre_gro_complete,
277 static int __init gre_offload_init(void)
279 return inet_add_offload(&gre_offload, IPPROTO_GRE);
281 device_initcall(gre_offload_init);