net: gre: move GSO functions to gre_offload
Similarly to TCP/UDP offloading, move all related GRE functions to
gre_offload.c to make things more explicit and similar to the rest
of the code.
Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/gre_offload.c b/net/ipv4/gre_offload.c
new file mode 100644
index 0000000..a9d8cd2
--- /dev/null
+++ b/net/ipv4/gre_offload.c
@@ -0,0 +1,127 @@
+/*
+ * IPV4 GSO/GRO offload support
+ * Linux INET implementation
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * GRE GSO support
+ */
+
+#include <linux/skbuff.h>
+#include <net/protocol.h>
+#include <net/gre.h>
+
+static int gre_gso_send_check(struct sk_buff *skb)
+{
+ if (!skb->encapsulation)
+ return -EINVAL;
+ return 0;
+}
+
+static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
+ netdev_features_t features)
+{
+ struct sk_buff *segs = ERR_PTR(-EINVAL);
+ netdev_features_t enc_features;
+ int ghl = GRE_HEADER_SECTION;
+ struct gre_base_hdr *greh;
+ int mac_len = skb->mac_len;
+ __be16 protocol = skb->protocol;
+ int tnl_hlen;
+ bool csum;
+
+ if (unlikely(skb_shinfo(skb)->gso_type &
+ ~(SKB_GSO_TCPV4 |
+ SKB_GSO_TCPV6 |
+ SKB_GSO_UDP |
+ SKB_GSO_DODGY |
+ SKB_GSO_TCP_ECN |
+ SKB_GSO_GRE)))
+ goto out;
+
+ if (unlikely(!pskb_may_pull(skb, sizeof(*greh))))
+ goto out;
+
+ greh = (struct gre_base_hdr *)skb_transport_header(skb);
+
+ if (greh->flags & GRE_KEY)
+ ghl += GRE_HEADER_SECTION;
+ if (greh->flags & GRE_SEQ)
+ ghl += GRE_HEADER_SECTION;
+ if (greh->flags & GRE_CSUM) {
+ ghl += GRE_HEADER_SECTION;
+ csum = true;
+ } else
+ csum = false;
+
+ /* setup inner skb. */
+ skb->protocol = greh->protocol;
+ skb->encapsulation = 0;
+
+ if (unlikely(!pskb_may_pull(skb, ghl)))
+ goto out;
+
+ __skb_pull(skb, ghl);
+ skb_reset_mac_header(skb);
+ skb_set_network_header(skb, skb_inner_network_offset(skb));
+ skb->mac_len = skb_inner_network_offset(skb);
+
+ /* segment inner packet. */
+ enc_features = skb->dev->hw_enc_features & netif_skb_features(skb);
+ segs = skb_mac_gso_segment(skb, enc_features);
+ if (!segs || IS_ERR(segs))
+ goto out;
+
+ skb = segs;
+ tnl_hlen = skb_tnl_header_len(skb);
+ do {
+ __skb_push(skb, ghl);
+ if (csum) {
+ __be32 *pcsum;
+
+ if (skb_has_shared_frag(skb)) {
+ int err;
+
+ err = __skb_linearize(skb);
+ if (err) {
+ kfree_skb(segs);
+ segs = ERR_PTR(err);
+ goto out;
+ }
+ }
+
+ greh = (struct gre_base_hdr *)(skb->data);
+ pcsum = (__be32 *)(greh + 1);
+ *pcsum = 0;
+ *(__sum16 *)pcsum = csum_fold(skb_checksum(skb, 0, skb->len, 0));
+ }
+ __skb_push(skb, tnl_hlen - ghl);
+
+ skb_reset_mac_header(skb);
+ skb_set_network_header(skb, mac_len);
+ skb->mac_len = mac_len;
+ skb->protocol = protocol;
+ } while ((skb = skb->next));
+out:
+ return segs;
+}
+
+static const struct net_offload gre_offload = {
+ .callbacks = {
+ .gso_send_check = gre_gso_send_check,
+ .gso_segment = gre_gso_segment,
+ },
+};
+
+int __init gre_offload_init(void)
+{
+ return inet_add_offload(&gre_offload, IPPROTO_GRE);
+}
+
+void __exit gre_offload_exit(void)
+{
+ inet_del_offload(&gre_offload, IPPROTO_GRE);
+}