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 &
43 if (!skb->encapsulation)
46 if (unlikely(tnl_hlen < sizeof(struct gre_base_hdr)))
49 if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
52 /* setup inner skb. */
53 skb->encapsulation = 0;
54 SKB_GSO_CB(skb)->encap_level = 0;
55 __skb_pull(skb, tnl_hlen);
56 skb_reset_mac_header(skb);
57 skb_set_network_header(skb, skb_inner_network_offset(skb));
58 skb->mac_len = skb_inner_network_offset(skb);
59 skb->protocol = skb->inner_protocol;
61 need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_GRE_CSUM);
62 skb->encap_hdr_csum = need_csum;
64 ufo = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP);
66 features &= skb->dev->hw_enc_features;
68 /* The only checksum offload we care about from here on out is the
69 * outer one so strip the existing checksum feature flags based
70 * on the fact that we will be computing our checksum in software.
73 features &= ~NETIF_F_CSUM_MASK;
75 features |= NETIF_F_HW_CSUM;
78 /* segment inner packet. */
79 segs = skb_mac_gso_segment(skb, features);
80 if (IS_ERR_OR_NULL(segs)) {
81 skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset,
86 outer_hlen = skb_tnl_header_len(skb);
87 gre_offset = outer_hlen - tnl_hlen;
90 struct gre_base_hdr *greh;
93 /* Set up inner headers if we are offloading inner checksum */
94 if (skb->ip_summed == CHECKSUM_PARTIAL) {
95 skb_reset_inner_headers(skb);
96 skb->encapsulation = 1;
99 skb->mac_len = mac_len;
100 skb->protocol = protocol;
102 __skb_push(skb, outer_hlen);
103 skb_reset_mac_header(skb);
104 skb_set_network_header(skb, mac_len);
105 skb_set_transport_header(skb, gre_offset);
110 greh = (struct gre_base_hdr *)skb_transport_header(skb);
111 pcsum = (__sum16 *)(greh + 1);
113 if (skb_is_gso(skb)) {
114 unsigned int partial_adj;
116 /* Adjust checksum to account for the fact that
117 * the partial checksum is based on actual size
118 * whereas headers should be based on MSS size.
120 partial_adj = skb->len + skb_headroom(skb) -
121 SKB_GSO_CB(skb)->data_offset -
122 skb_shinfo(skb)->gso_size;
123 *pcsum = ~csum_fold((__force __wsum)htonl(partial_adj));
129 *pcsum = gso_make_checksum(skb, 0);
130 } while ((skb = skb->next));
135 static struct sk_buff **gre_gro_receive(struct sk_buff **head,
138 struct sk_buff **pp = NULL;
140 const struct gre_base_hdr *greh;
141 unsigned int hlen, grehlen;
144 struct packet_offload *ptype;
147 if (NAPI_GRO_CB(skb)->encap_mark)
150 NAPI_GRO_CB(skb)->encap_mark = 1;
152 off = skb_gro_offset(skb);
153 hlen = off + sizeof(*greh);
154 greh = skb_gro_header_fast(skb, off);
155 if (skb_gro_header_hard(skb, hlen)) {
156 greh = skb_gro_header_slow(skb, hlen, off);
161 /* Only support version 0 and K (key), C (csum) flags. Note that
162 * although the support for the S (seq#) flag can be added easily
163 * for GRO, this is problematic for GSO hence can not be enabled
164 * here because a GRO pkt may end up in the forwarding path, thus
165 * requiring GSO support to break it up correctly.
167 if ((greh->flags & ~(GRE_KEY|GRE_CSUM)) != 0)
170 /* We can only support GRE_CSUM if we can track the location of
171 * the GRE header. In the case of FOU/GUE we cannot because the
172 * outer UDP header displaces the GRE header leaving us in a state
175 if ((greh->flags & GRE_CSUM) && NAPI_GRO_CB(skb)->is_fou)
178 type = greh->protocol;
181 ptype = gro_find_receive_by_type(type);
185 grehlen = GRE_HEADER_SECTION;
187 if (greh->flags & GRE_KEY)
188 grehlen += GRE_HEADER_SECTION;
190 if (greh->flags & GRE_CSUM)
191 grehlen += GRE_HEADER_SECTION;
193 hlen = off + grehlen;
194 if (skb_gro_header_hard(skb, hlen)) {
195 greh = skb_gro_header_slow(skb, hlen, off);
200 /* Don't bother verifying checksum if we're going to flush anyway. */
201 if ((greh->flags & GRE_CSUM) && !NAPI_GRO_CB(skb)->flush) {
202 if (skb_gro_checksum_simple_validate(skb))
205 skb_gro_checksum_try_convert(skb, IPPROTO_GRE, 0,
206 null_compute_pseudo);
209 for (p = *head; p; p = p->next) {
210 const struct gre_base_hdr *greh2;
212 if (!NAPI_GRO_CB(p)->same_flow)
215 /* The following checks are needed to ensure only pkts
216 * from the same tunnel are considered for aggregation.
217 * The criteria for "the same tunnel" includes:
218 * 1) same version (we only support version 0 here)
219 * 2) same protocol (we only support ETH_P_IP for now)
220 * 3) same set of flags
221 * 4) same key if the key field is present.
223 greh2 = (struct gre_base_hdr *)(p->data + off);
225 if (greh2->flags != greh->flags ||
226 greh2->protocol != greh->protocol) {
227 NAPI_GRO_CB(p)->same_flow = 0;
230 if (greh->flags & GRE_KEY) {
232 if (*(__be32 *)(greh2+1) != *(__be32 *)(greh+1)) {
233 NAPI_GRO_CB(p)->same_flow = 0;
239 skb_gro_pull(skb, grehlen);
241 /* Adjusted NAPI_GRO_CB(skb)->csum after skb_gro_pull()*/
242 skb_gro_postpull_rcsum(skb, greh, grehlen);
244 pp = ptype->callbacks.gro_receive(head, skb);
250 NAPI_GRO_CB(skb)->flush |= flush;
255 static int gre_gro_complete(struct sk_buff *skb, int nhoff)
257 struct gre_base_hdr *greh = (struct gre_base_hdr *)(skb->data + nhoff);
258 struct packet_offload *ptype;
259 unsigned int grehlen = sizeof(*greh);
263 skb->encapsulation = 1;
264 skb_shinfo(skb)->gso_type = SKB_GSO_GRE;
266 type = greh->protocol;
267 if (greh->flags & GRE_KEY)
268 grehlen += GRE_HEADER_SECTION;
270 if (greh->flags & GRE_CSUM)
271 grehlen += GRE_HEADER_SECTION;
274 ptype = gro_find_complete_by_type(type);
276 err = ptype->callbacks.gro_complete(skb, nhoff + grehlen);
280 skb_set_inner_mac_header(skb, nhoff + grehlen);
285 static const struct net_offload gre_offload = {
287 .gso_segment = gre_gso_segment,
288 .gro_receive = gre_gro_receive,
289 .gro_complete = gre_gro_complete,
293 static int __init gre_offload_init(void)
297 err = inet_add_offload(&gre_offload, IPPROTO_GRE);
298 #if IS_ENABLED(CONFIG_IPV6)
302 err = inet6_add_offload(&gre_offload, IPPROTO_GRE);
304 inet_del_offload(&gre_offload, IPPROTO_GRE);
309 device_initcall(gre_offload_init);