--- /dev/null
+/*
+ * 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 <linux/init.h>
+#include <net/protocol.h>
+#include <net/gre.h>
+
+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;
+ struct gre_base_hdr *greh;
+ u16 mac_offset = skb->mac_header;
+ 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 |
+ SKB_GSO_GRE_CSUM |
+ SKB_GSO_IPIP)))
+ goto out;
+
+ if (!skb->encapsulation)
+ goto out;
+
+ if (unlikely(!pskb_may_pull(skb, sizeof(*greh))))
+ goto out;
+
+ greh = (struct gre_base_hdr *)skb_transport_header(skb);
+
+ ghl = skb_inner_mac_header(skb) - skb_transport_header(skb);
+ if (unlikely(ghl < sizeof(*greh)))
+ goto out;
+
+ csum = !!(greh->flags & GRE_CSUM);
+ if (csum)
+ skb->encap_hdr_csum = 1;
+
+ /* 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 & features;
+ segs = skb_mac_gso_segment(skb, enc_features);
+ if (IS_ERR_OR_NULL(segs)) {
+ skb_gso_error_unwind(skb, protocol, ghl, mac_offset, mac_len);
+ 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_list(segs);
+ segs = ERR_PTR(err);
+ goto out;
+ }
+ }
+
+ skb_reset_transport_header(skb);
+
+ greh = (struct gre_base_hdr *)
+ skb_transport_header(skb);
+ pcsum = (__be32 *)(greh + 1);
+ *pcsum = 0;
+ *(__sum16 *)pcsum = gso_make_checksum(skb, 0);
+ }
+ __skb_push(skb, tnl_hlen - ghl);
+
+ skb_reset_inner_headers(skb);
+ skb->encapsulation = 1;
+
+ 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 struct sk_buff **gre_gro_receive(struct sk_buff **head,
+ struct sk_buff *skb)
+{
+ struct sk_buff **pp = NULL;
+ struct sk_buff *p;
+ const struct gre_base_hdr *greh;
+ unsigned int hlen, grehlen;
+ unsigned int off;
+ int flush = 1;
+ struct packet_offload *ptype;
+ __be16 type;
+
+ off = skb_gro_offset(skb);
+ hlen = off + sizeof(*greh);
+ greh = skb_gro_header_fast(skb, off);
+ if (skb_gro_header_hard(skb, hlen)) {
+ greh = skb_gro_header_slow(skb, hlen, off);
+ if (unlikely(!greh))
+ goto out;
+ }
+
+ /* Only support version 0 and K (key), C (csum) flags. Note that
+ * although the support for the S (seq#) flag can be added easily
+ * for GRO, this is problematic for GSO hence can not be enabled
+ * here because a GRO pkt may end up in the forwarding path, thus
+ * requiring GSO support to break it up correctly.
+ */
+ if ((greh->flags & ~(GRE_KEY|GRE_CSUM)) != 0)
+ goto out;
+
+ type = greh->protocol;
+
+ rcu_read_lock();
+ ptype = gro_find_receive_by_type(type);
+ if (!ptype)
+ goto out_unlock;
+
+ grehlen = GRE_HEADER_SECTION;
+
+ if (greh->flags & GRE_KEY)
+ grehlen += GRE_HEADER_SECTION;
+
+ if (greh->flags & GRE_CSUM)
+ grehlen += GRE_HEADER_SECTION;
+
+ hlen = off + grehlen;
+ if (skb_gro_header_hard(skb, hlen)) {
+ greh = skb_gro_header_slow(skb, hlen, off);
+ if (unlikely(!greh))
+ goto out_unlock;
+ }
+
+ /* Don't bother verifying checksum if we're going to flush anyway. */
+ if ((greh->flags & GRE_CSUM) && !NAPI_GRO_CB(skb)->flush) {
+ if (skb_gro_checksum_simple_validate(skb))
+ goto out_unlock;
+
+ skb_gro_checksum_try_convert(skb, IPPROTO_GRE, 0,
+ null_compute_pseudo);
+ }
+
+ flush = 0;
+
+ for (p = *head; p; p = p->next) {
+ const struct gre_base_hdr *greh2;
+
+ if (!NAPI_GRO_CB(p)->same_flow)
+ continue;
+
+ /* The following checks are needed to ensure only pkts
+ * from the same tunnel are considered for aggregation.
+ * The criteria for "the same tunnel" includes:
+ * 1) same version (we only support version 0 here)
+ * 2) same protocol (we only support ETH_P_IP for now)
+ * 3) same set of flags
+ * 4) same key if the key field is present.
+ */
+ greh2 = (struct gre_base_hdr *)(p->data + off);
+
+ if (greh2->flags != greh->flags ||
+ greh2->protocol != greh->protocol) {
+ NAPI_GRO_CB(p)->same_flow = 0;
+ continue;
+ }
+ if (greh->flags & GRE_KEY) {
+ /* compare keys */
+ if (*(__be32 *)(greh2+1) != *(__be32 *)(greh+1)) {
+ NAPI_GRO_CB(p)->same_flow = 0;
+ continue;
+ }
+ }
+ }
+
+ skb_gro_pull(skb, grehlen);
+
+ /* Adjusted NAPI_GRO_CB(skb)->csum after skb_gro_pull()*/
+ skb_gro_postpull_rcsum(skb, greh, grehlen);
+
+ pp = ptype->callbacks.gro_receive(head, skb);
+
+out_unlock:
+ rcu_read_unlock();
+out:
+ NAPI_GRO_CB(skb)->flush |= flush;
+
+ return pp;
+}
+
+static int gre_gro_complete(struct sk_buff *skb, int nhoff)
+{
+ struct gre_base_hdr *greh = (struct gre_base_hdr *)(skb->data + nhoff);
+ struct packet_offload *ptype;
+ unsigned int grehlen = sizeof(*greh);
+ int err = -ENOENT;
+ __be16 type;
+
+ skb->encapsulation = 1;
+ skb_shinfo(skb)->gso_type = SKB_GSO_GRE;
+
+ type = greh->protocol;
+ if (greh->flags & GRE_KEY)
+ grehlen += GRE_HEADER_SECTION;
+
+ if (greh->flags & GRE_CSUM)
+ grehlen += GRE_HEADER_SECTION;
+
+ rcu_read_lock();
+ ptype = gro_find_complete_by_type(type);
+ if (ptype)
+ err = ptype->callbacks.gro_complete(skb, nhoff + grehlen);
+
+ rcu_read_unlock();
+
+ skb_set_inner_mac_header(skb, nhoff + grehlen);
+
+ return err;
+}
+
+static const struct net_offload gre_offload = {
+ .callbacks = {
+ .gso_segment = gre_gso_segment,
+ .gro_receive = gre_gro_receive,
+ .gro_complete = gre_gro_complete,
+ },
+};
+
+static int __init gre_offload_init(void)
+{
+ return inet_add_offload(&gre_offload, IPPROTO_GRE);
+}
+device_initcall(gre_offload_init);
Code Review / kvmfornfv.git / blobdiff