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;
27 bool need_csum, gso_partial;
29 if (!skb->encapsulation)
32 if (unlikely(tnl_hlen < sizeof(struct gre_base_hdr)))
35 if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
38 /* setup inner skb. */
39 skb->encapsulation = 0;
40 SKB_GSO_CB(skb)->encap_level = 0;
41 __skb_pull(skb, tnl_hlen);
42 skb_reset_mac_header(skb);
43 skb_set_network_header(skb, skb_inner_network_offset(skb));
44 skb->mac_len = skb_inner_network_offset(skb);
45 skb->protocol = skb->inner_protocol;
47 need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_GRE_CSUM);
48 skb->encap_hdr_csum = need_csum;
50 features &= skb->dev->hw_enc_features;
52 /* segment inner packet. */
53 segs = skb_mac_gso_segment(skb, features);
54 if (IS_ERR_OR_NULL(segs)) {
55 skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset,
60 gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL);
62 outer_hlen = skb_tnl_header_len(skb);
63 gre_offset = outer_hlen - tnl_hlen;
66 struct gre_base_hdr *greh;
69 /* Set up inner headers if we are offloading inner checksum */
70 if (skb->ip_summed == CHECKSUM_PARTIAL) {
71 skb_reset_inner_headers(skb);
72 skb->encapsulation = 1;
75 skb->mac_len = mac_len;
76 skb->protocol = protocol;
78 __skb_push(skb, outer_hlen);
79 skb_reset_mac_header(skb);
80 skb_set_network_header(skb, mac_len);
81 skb_set_transport_header(skb, gre_offset);
86 greh = (struct gre_base_hdr *)skb_transport_header(skb);
87 pcsum = (__sum16 *)(greh + 1);
89 if (gso_partial && skb_is_gso(skb)) {
90 unsigned int partial_adj;
92 /* Adjust checksum to account for the fact that
93 * the partial checksum is based on actual size
94 * whereas headers should be based on MSS size.
96 partial_adj = skb->len + skb_headroom(skb) -
97 SKB_GSO_CB(skb)->data_offset -
98 skb_shinfo(skb)->gso_size;
99 *pcsum = ~csum_fold((__force __wsum)htonl(partial_adj));
105 *pcsum = gso_make_checksum(skb, 0);
106 } while ((skb = skb->next));
111 static struct sk_buff **gre_gro_receive(struct sk_buff **head,
114 struct sk_buff **pp = NULL;
116 const struct gre_base_hdr *greh;
117 unsigned int hlen, grehlen;
120 struct packet_offload *ptype;
123 if (NAPI_GRO_CB(skb)->encap_mark)
126 NAPI_GRO_CB(skb)->encap_mark = 1;
128 off = skb_gro_offset(skb);
129 hlen = off + sizeof(*greh);
130 greh = skb_gro_header_fast(skb, off);
131 if (skb_gro_header_hard(skb, hlen)) {
132 greh = skb_gro_header_slow(skb, hlen, off);
137 /* Only support version 0 and K (key), C (csum) flags. Note that
138 * although the support for the S (seq#) flag can be added easily
139 * for GRO, this is problematic for GSO hence can not be enabled
140 * here because a GRO pkt may end up in the forwarding path, thus
141 * requiring GSO support to break it up correctly.
143 if ((greh->flags & ~(GRE_KEY|GRE_CSUM)) != 0)
146 /* We can only support GRE_CSUM if we can track the location of
147 * the GRE header. In the case of FOU/GUE we cannot because the
148 * outer UDP header displaces the GRE header leaving us in a state
151 if ((greh->flags & GRE_CSUM) && NAPI_GRO_CB(skb)->is_fou)
154 type = greh->protocol;
157 ptype = gro_find_receive_by_type(type);
161 grehlen = GRE_HEADER_SECTION;
163 if (greh->flags & GRE_KEY)
164 grehlen += GRE_HEADER_SECTION;
166 if (greh->flags & GRE_CSUM)
167 grehlen += GRE_HEADER_SECTION;
169 hlen = off + grehlen;
170 if (skb_gro_header_hard(skb, hlen)) {
171 greh = skb_gro_header_slow(skb, hlen, off);
176 /* Don't bother verifying checksum if we're going to flush anyway. */
177 if ((greh->flags & GRE_CSUM) && !NAPI_GRO_CB(skb)->flush) {
178 if (skb_gro_checksum_simple_validate(skb))
181 skb_gro_checksum_try_convert(skb, IPPROTO_GRE, 0,
182 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 = call_gro_receive(ptype->callbacks.gro_receive, head, skb);
226 NAPI_GRO_CB(skb)->flush |= flush;
231 static int gre_gro_complete(struct sk_buff *skb, int nhoff)
233 struct gre_base_hdr *greh = (struct gre_base_hdr *)(skb->data + nhoff);
234 struct packet_offload *ptype;
235 unsigned int grehlen = sizeof(*greh);
239 skb->encapsulation = 1;
240 skb_shinfo(skb)->gso_type = SKB_GSO_GRE;
242 type = greh->protocol;
243 if (greh->flags & GRE_KEY)
244 grehlen += GRE_HEADER_SECTION;
246 if (greh->flags & GRE_CSUM)
247 grehlen += GRE_HEADER_SECTION;
250 ptype = gro_find_complete_by_type(type);
252 err = ptype->callbacks.gro_complete(skb, nhoff + grehlen);
256 skb_set_inner_mac_header(skb, nhoff + grehlen);
261 static const struct net_offload gre_offload = {
263 .gso_segment = gre_gso_segment,
264 .gro_receive = gre_gro_receive,
265 .gro_complete = gre_gro_complete,
269 static int __init gre_offload_init(void)
273 err = inet_add_offload(&gre_offload, IPPROTO_GRE);
274 #if IS_ENABLED(CONFIG_IPV6)
278 err = inet6_add_offload(&gre_offload, IPPROTO_GRE);
280 inet_del_offload(&gre_offload, IPPROTO_GRE);
285 device_initcall(gre_offload_init);