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 &
41 if (!skb->encapsulation)
44 if (unlikely(tnl_hlen < sizeof(struct gre_base_hdr)))
47 if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
50 /* setup inner skb. */
51 skb->encapsulation = 0;
52 SKB_GSO_CB(skb)->encap_level = 0;
53 __skb_pull(skb, tnl_hlen);
54 skb_reset_mac_header(skb);
55 skb_set_network_header(skb, skb_inner_network_offset(skb));
56 skb->mac_len = skb_inner_network_offset(skb);
57 skb->protocol = skb->inner_protocol;
59 need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_GRE_CSUM);
60 skb->encap_hdr_csum = need_csum;
62 ufo = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP);
64 features &= skb->dev->hw_enc_features;
66 /* The only checksum offload we care about from here on out is the
67 * outer one so strip the existing checksum feature flags based
68 * on the fact that we will be computing our checksum in software.
71 features &= ~NETIF_F_CSUM_MASK;
73 features |= NETIF_F_HW_CSUM;
76 /* segment inner packet. */
77 segs = skb_mac_gso_segment(skb, features);
78 if (IS_ERR_OR_NULL(segs)) {
79 skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset,
84 outer_hlen = skb_tnl_header_len(skb);
85 gre_offset = outer_hlen - tnl_hlen;
88 struct gre_base_hdr *greh;
91 /* Set up inner headers if we are offloading inner checksum */
92 if (skb->ip_summed == CHECKSUM_PARTIAL) {
93 skb_reset_inner_headers(skb);
94 skb->encapsulation = 1;
97 skb->mac_len = mac_len;
98 skb->protocol = protocol;
100 __skb_push(skb, outer_hlen);
101 skb_reset_mac_header(skb);
102 skb_set_network_header(skb, mac_len);
103 skb_set_transport_header(skb, gre_offset);
108 greh = (struct gre_base_hdr *)skb_transport_header(skb);
109 pcsum = (__be32 *)(greh + 1);
112 *(__sum16 *)pcsum = gso_make_checksum(skb, 0);
113 } while ((skb = skb->next));
118 static struct sk_buff **gre_gro_receive(struct sk_buff **head,
121 struct sk_buff **pp = NULL;
123 const struct gre_base_hdr *greh;
124 unsigned int hlen, grehlen;
127 struct packet_offload *ptype;
130 if (NAPI_GRO_CB(skb)->encap_mark)
133 NAPI_GRO_CB(skb)->encap_mark = 1;
135 off = skb_gro_offset(skb);
136 hlen = off + sizeof(*greh);
137 greh = skb_gro_header_fast(skb, off);
138 if (skb_gro_header_hard(skb, hlen)) {
139 greh = skb_gro_header_slow(skb, hlen, off);
144 /* Only support version 0 and K (key), C (csum) flags. Note that
145 * although the support for the S (seq#) flag can be added easily
146 * for GRO, this is problematic for GSO hence can not be enabled
147 * here because a GRO pkt may end up in the forwarding path, thus
148 * requiring GSO support to break it up correctly.
150 if ((greh->flags & ~(GRE_KEY|GRE_CSUM)) != 0)
153 /* We can only support GRE_CSUM if we can track the location of
154 * the GRE header. In the case of FOU/GUE we cannot because the
155 * outer UDP header displaces the GRE header leaving us in a state
158 if ((greh->flags & GRE_CSUM) && NAPI_GRO_CB(skb)->is_fou)
161 type = greh->protocol;
164 ptype = gro_find_receive_by_type(type);
168 grehlen = GRE_HEADER_SECTION;
170 if (greh->flags & GRE_KEY)
171 grehlen += GRE_HEADER_SECTION;
173 if (greh->flags & GRE_CSUM)
174 grehlen += GRE_HEADER_SECTION;
176 hlen = off + grehlen;
177 if (skb_gro_header_hard(skb, hlen)) {
178 greh = skb_gro_header_slow(skb, hlen, off);
183 /* Don't bother verifying checksum if we're going to flush anyway. */
184 if ((greh->flags & GRE_CSUM) && !NAPI_GRO_CB(skb)->flush) {
185 if (skb_gro_checksum_simple_validate(skb))
188 skb_gro_checksum_try_convert(skb, IPPROTO_GRE, 0,
189 null_compute_pseudo);
192 for (p = *head; p; p = p->next) {
193 const struct gre_base_hdr *greh2;
195 if (!NAPI_GRO_CB(p)->same_flow)
198 /* The following checks are needed to ensure only pkts
199 * from the same tunnel are considered for aggregation.
200 * The criteria for "the same tunnel" includes:
201 * 1) same version (we only support version 0 here)
202 * 2) same protocol (we only support ETH_P_IP for now)
203 * 3) same set of flags
204 * 4) same key if the key field is present.
206 greh2 = (struct gre_base_hdr *)(p->data + off);
208 if (greh2->flags != greh->flags ||
209 greh2->protocol != greh->protocol) {
210 NAPI_GRO_CB(p)->same_flow = 0;
213 if (greh->flags & GRE_KEY) {
215 if (*(__be32 *)(greh2+1) != *(__be32 *)(greh+1)) {
216 NAPI_GRO_CB(p)->same_flow = 0;
222 skb_gro_pull(skb, grehlen);
224 /* Adjusted NAPI_GRO_CB(skb)->csum after skb_gro_pull()*/
225 skb_gro_postpull_rcsum(skb, greh, grehlen);
227 pp = ptype->callbacks.gro_receive(head, skb);
233 NAPI_GRO_CB(skb)->flush |= flush;
238 static int gre_gro_complete(struct sk_buff *skb, int nhoff)
240 struct gre_base_hdr *greh = (struct gre_base_hdr *)(skb->data + nhoff);
241 struct packet_offload *ptype;
242 unsigned int grehlen = sizeof(*greh);
246 skb->encapsulation = 1;
247 skb_shinfo(skb)->gso_type = SKB_GSO_GRE;
249 type = greh->protocol;
250 if (greh->flags & GRE_KEY)
251 grehlen += GRE_HEADER_SECTION;
253 if (greh->flags & GRE_CSUM)
254 grehlen += GRE_HEADER_SECTION;
257 ptype = gro_find_complete_by_type(type);
259 err = ptype->callbacks.gro_complete(skb, nhoff + grehlen);
263 skb_set_inner_mac_header(skb, nhoff + grehlen);
268 static const struct net_offload gre_offload = {
270 .gso_segment = gre_gso_segment,
271 .gro_receive = gre_gro_receive,
272 .gro_complete = gre_gro_complete,
276 static int __init gre_offload_init(void)
278 return inet_add_offload(&gre_offload, IPPROTO_GRE);
280 device_initcall(gre_offload_init);