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 bool need_csum, need_recompute_csum, gso_partial;
23 struct sk_buff *segs = ERR_PTR(-EINVAL);
24 u16 mac_offset = skb->mac_header;
25 __be16 protocol = skb->protocol;
26 u16 mac_len = skb->mac_len;
27 int gre_offset, outer_hlen;
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 need_recompute_csum = skb->csum_not_inet;
49 skb->encap_hdr_csum = need_csum;
51 features &= skb->dev->hw_enc_features;
53 /* segment inner packet. */
54 segs = skb_mac_gso_segment(skb, features);
55 if (IS_ERR_OR_NULL(segs)) {
56 skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset,
61 gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL);
63 outer_hlen = skb_tnl_header_len(skb);
64 gre_offset = outer_hlen - tnl_hlen;
67 struct gre_base_hdr *greh;
70 /* Set up inner headers if we are offloading inner checksum */
71 if (skb->ip_summed == CHECKSUM_PARTIAL) {
72 skb_reset_inner_headers(skb);
73 skb->encapsulation = 1;
76 skb->mac_len = mac_len;
77 skb->protocol = protocol;
79 __skb_push(skb, outer_hlen);
80 skb_reset_mac_header(skb);
81 skb_set_network_header(skb, mac_len);
82 skb_set_transport_header(skb, gre_offset);
87 greh = (struct gre_base_hdr *)skb_transport_header(skb);
88 pcsum = (__sum16 *)(greh + 1);
90 if (gso_partial && skb_is_gso(skb)) {
91 unsigned int partial_adj;
93 /* Adjust checksum to account for the fact that
94 * the partial checksum is based on actual size
95 * whereas headers should be based on MSS size.
97 partial_adj = skb->len + skb_headroom(skb) -
98 SKB_GSO_CB(skb)->data_offset -
99 skb_shinfo(skb)->gso_size;
100 *pcsum = ~csum_fold((__force __wsum)htonl(partial_adj));
106 if (need_recompute_csum && !skb_is_gso(skb)) {
109 csum = skb_checksum(skb, gre_offset,
110 skb->len - gre_offset, 0);
111 *pcsum = csum_fold(csum);
113 *pcsum = gso_make_checksum(skb, 0);
115 } while ((skb = skb->next));
120 static struct sk_buff *gre_gro_receive(struct list_head *head,
123 struct sk_buff *pp = NULL;
125 const struct gre_base_hdr *greh;
126 unsigned int hlen, grehlen;
129 struct packet_offload *ptype;
132 if (NAPI_GRO_CB(skb)->encap_mark)
135 NAPI_GRO_CB(skb)->encap_mark = 1;
137 off = skb_gro_offset(skb);
138 hlen = off + sizeof(*greh);
139 greh = skb_gro_header_fast(skb, off);
140 if (skb_gro_header_hard(skb, hlen)) {
141 greh = skb_gro_header_slow(skb, hlen, off);
146 /* Only support version 0 and K (key), C (csum) flags. Note that
147 * although the support for the S (seq#) flag can be added easily
148 * for GRO, this is problematic for GSO hence can not be enabled
149 * here because a GRO pkt may end up in the forwarding path, thus
150 * requiring GSO support to break it up correctly.
152 if ((greh->flags & ~(GRE_KEY|GRE_CSUM)) != 0)
155 /* We can only support GRE_CSUM if we can track the location of
156 * the GRE header. In the case of FOU/GUE we cannot because the
157 * outer UDP header displaces the GRE header leaving us in a state
160 if ((greh->flags & GRE_CSUM) && NAPI_GRO_CB(skb)->is_fou)
163 type = greh->protocol;
166 ptype = gro_find_receive_by_type(type);
170 grehlen = GRE_HEADER_SECTION;
172 if (greh->flags & GRE_KEY)
173 grehlen += GRE_HEADER_SECTION;
175 if (greh->flags & GRE_CSUM)
176 grehlen += GRE_HEADER_SECTION;
178 hlen = off + grehlen;
179 if (skb_gro_header_hard(skb, hlen)) {
180 greh = skb_gro_header_slow(skb, hlen, off);
185 /* Don't bother verifying checksum if we're going to flush anyway. */
186 if ((greh->flags & GRE_CSUM) && !NAPI_GRO_CB(skb)->flush) {
187 if (skb_gro_checksum_simple_validate(skb))
190 skb_gro_checksum_try_convert(skb, IPPROTO_GRE, 0,
191 null_compute_pseudo);
194 list_for_each_entry(p, head, list) {
195 const struct gre_base_hdr *greh2;
197 if (!NAPI_GRO_CB(p)->same_flow)
200 /* The following checks are needed to ensure only pkts
201 * from the same tunnel are considered for aggregation.
202 * The criteria for "the same tunnel" includes:
203 * 1) same version (we only support version 0 here)
204 * 2) same protocol (we only support ETH_P_IP for now)
205 * 3) same set of flags
206 * 4) same key if the key field is present.
208 greh2 = (struct gre_base_hdr *)(p->data + off);
210 if (greh2->flags != greh->flags ||
211 greh2->protocol != greh->protocol) {
212 NAPI_GRO_CB(p)->same_flow = 0;
215 if (greh->flags & GRE_KEY) {
217 if (*(__be32 *)(greh2+1) != *(__be32 *)(greh+1)) {
218 NAPI_GRO_CB(p)->same_flow = 0;
224 skb_gro_pull(skb, grehlen);
226 /* Adjusted NAPI_GRO_CB(skb)->csum after skb_gro_pull()*/
227 skb_gro_postpull_rcsum(skb, greh, grehlen);
229 pp = call_gro_receive(ptype->callbacks.gro_receive, head, skb);
235 skb_gro_flush_final(skb, pp, 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)
282 err = inet_add_offload(&gre_offload, IPPROTO_GRE);
283 #if IS_ENABLED(CONFIG_IPV6)
287 err = inet6_add_offload(&gre_offload, IPPROTO_GRE);
289 inet_del_offload(&gre_offload, IPPROTO_GRE);
294 device_initcall(gre_offload_init);