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 int gre_gso_send_check(struct sk_buff *skb)
20 if (!skb->encapsulation)
25 static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
26 netdev_features_t features)
28 struct sk_buff *segs = ERR_PTR(-EINVAL);
29 netdev_features_t enc_features;
31 struct gre_base_hdr *greh;
32 u16 mac_offset = skb->mac_header;
33 int mac_len = skb->mac_len;
34 __be16 protocol = skb->protocol;
38 if (unlikely(skb_shinfo(skb)->gso_type &
48 if (unlikely(!pskb_may_pull(skb, sizeof(*greh))))
51 greh = (struct gre_base_hdr *)skb_transport_header(skb);
53 ghl = skb_inner_network_header(skb) - skb_transport_header(skb);
54 if (unlikely(ghl < sizeof(*greh)))
57 csum = !!(greh->flags & GRE_CSUM);
59 if (unlikely(!pskb_may_pull(skb, ghl)))
62 /* setup inner skb. */
63 skb->protocol = greh->protocol;
64 skb->encapsulation = 0;
67 skb_reset_mac_header(skb);
68 skb_set_network_header(skb, skb_inner_network_offset(skb));
69 skb->mac_len = skb_inner_network_offset(skb);
71 /* segment inner packet. */
72 enc_features = skb->dev->hw_enc_features & netif_skb_features(skb);
73 segs = skb_mac_gso_segment(skb, enc_features);
74 if (!segs || IS_ERR(segs)) {
75 skb_gso_error_unwind(skb, protocol, ghl, mac_offset, mac_len);
80 tnl_hlen = skb_tnl_header_len(skb);
86 if (skb_has_shared_frag(skb)) {
89 err = __skb_linearize(skb);
97 greh = (struct gre_base_hdr *)(skb->data);
98 pcsum = (__be32 *)(greh + 1);
100 *(__sum16 *)pcsum = csum_fold(skb_checksum(skb, 0, skb->len, 0));
102 __skb_push(skb, tnl_hlen - ghl);
104 skb_reset_inner_headers(skb);
105 skb->encapsulation = 1;
107 skb_reset_mac_header(skb);
108 skb_set_network_header(skb, mac_len);
109 skb->mac_len = mac_len;
110 skb->protocol = protocol;
111 } while ((skb = skb->next));
116 /* Compute the whole skb csum in s/w and store it, then verify GRO csum
117 * starting from gro_offset.
119 static __sum16 gro_skb_checksum(struct sk_buff *skb)
123 skb->csum = skb_checksum(skb, 0, skb->len, 0);
124 NAPI_GRO_CB(skb)->csum = csum_sub(skb->csum,
125 csum_partial(skb->data, skb_gro_offset(skb), 0));
126 sum = csum_fold(NAPI_GRO_CB(skb)->csum);
127 if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE)) {
129 netdev_rx_csum_fault(skb->dev);
131 skb->ip_summed = CHECKSUM_COMPLETE;
136 static struct sk_buff **gre_gro_receive(struct sk_buff **head,
139 struct sk_buff **pp = NULL;
141 const struct gre_base_hdr *greh;
142 unsigned int hlen, grehlen;
145 struct packet_offload *ptype;
148 off = skb_gro_offset(skb);
149 hlen = off + sizeof(*greh);
150 greh = skb_gro_header_fast(skb, off);
151 if (skb_gro_header_hard(skb, hlen)) {
152 greh = skb_gro_header_slow(skb, hlen, off);
157 /* Only support version 0 and K (key), C (csum) flags. Note that
158 * although the support for the S (seq#) flag can be added easily
159 * for GRO, this is problematic for GSO hence can not be enabled
160 * here because a GRO pkt may end up in the forwarding path, thus
161 * requiring GSO support to break it up correctly.
163 if ((greh->flags & ~(GRE_KEY|GRE_CSUM)) != 0)
166 type = greh->protocol;
169 ptype = gro_find_receive_by_type(type);
173 grehlen = GRE_HEADER_SECTION;
175 if (greh->flags & GRE_KEY)
176 grehlen += GRE_HEADER_SECTION;
178 if (greh->flags & GRE_CSUM)
179 grehlen += GRE_HEADER_SECTION;
181 hlen = off + grehlen;
182 if (skb_gro_header_hard(skb, hlen)) {
183 greh = skb_gro_header_slow(skb, hlen, off);
187 if (greh->flags & GRE_CSUM) { /* Need to verify GRE csum first */
190 if (skb->ip_summed == CHECKSUM_COMPLETE)
191 csum = csum_fold(NAPI_GRO_CB(skb)->csum);
192 /* Don't trust csum error calculated/reported by h/w */
193 if (skb->ip_summed == CHECKSUM_NONE || csum != 0)
194 csum = gro_skb_checksum(skb);
196 /* GRE CSUM is the 1's complement of the 1's complement sum
197 * of the GRE hdr plus payload so it should add up to 0xffff
198 * (and 0 after csum_fold()) just like the IPv4 hdr csum.
205 for (p = *head; p; p = p->next) {
206 const struct gre_base_hdr *greh2;
208 if (!NAPI_GRO_CB(p)->same_flow)
211 /* The following checks are needed to ensure only pkts
212 * from the same tunnel are considered for aggregation.
213 * The criteria for "the same tunnel" includes:
214 * 1) same version (we only support version 0 here)
215 * 2) same protocol (we only support ETH_P_IP for now)
216 * 3) same set of flags
217 * 4) same key if the key field is present.
219 greh2 = (struct gre_base_hdr *)(p->data + off);
221 if (greh2->flags != greh->flags ||
222 greh2->protocol != greh->protocol) {
223 NAPI_GRO_CB(p)->same_flow = 0;
226 if (greh->flags & GRE_KEY) {
228 if (*(__be32 *)(greh2+1) != *(__be32 *)(greh+1)) {
229 NAPI_GRO_CB(p)->same_flow = 0;
235 skb_gro_pull(skb, grehlen);
237 /* Adjusted NAPI_GRO_CB(skb)->csum after skb_gro_pull()*/
238 skb_gro_postpull_rcsum(skb, greh, grehlen);
240 pp = ptype->callbacks.gro_receive(head, skb);
245 NAPI_GRO_CB(skb)->flush |= flush;
250 static int gre_gro_complete(struct sk_buff *skb, int nhoff)
252 struct gre_base_hdr *greh = (struct gre_base_hdr *)(skb->data + nhoff);
253 struct packet_offload *ptype;
254 unsigned int grehlen = sizeof(*greh);
258 type = greh->protocol;
259 if (greh->flags & GRE_KEY)
260 grehlen += GRE_HEADER_SECTION;
262 if (greh->flags & GRE_CSUM)
263 grehlen += GRE_HEADER_SECTION;
266 ptype = gro_find_complete_by_type(type);
268 err = ptype->callbacks.gro_complete(skb, nhoff + grehlen);
274 static const struct net_offload gre_offload = {
276 .gso_send_check = gre_gso_send_check,
277 .gso_segment = gre_gso_segment,
278 .gro_receive = gre_gro_receive,
279 .gro_complete = gre_gro_complete,
283 static int __init gre_offload_init(void)
285 return inet_add_offload(&gre_offload, IPPROTO_GRE);
287 device_initcall(gre_offload_init);