![Pravin B Shelar](/assets/img/avatar_default.png)
Following patch adds GRE protocol offload handler so that skb_gso_segment() can segment GRE packets. SKB GSO CB is added to keep track of total header length so that skb_segment can push entire header. e.g. in case of GRE, skb_segment need to push inner and outer headers to every segment. New NETIF_F_GRE_GSO feature is added for devices which support HW GRE TSO offload. Currently none of devices support it therefore GRE GSO always fall backs to software GSO. [ Compute pkt_len before ip_local_out() invocation. -DaveM ] Signed-off-by: Pravin B Shelar <pshelar@nicira.com> Signed-off-by: David S. Miller <davem@davemloft.net>
263 lines
5.6 KiB
C
263 lines
5.6 KiB
C
/*
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* GRE over IPv4 demultiplexer driver
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*
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* Authors: Dmitry Kozlov (xeb@mail.ru)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/kmod.h>
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#include <linux/skbuff.h>
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#include <linux/in.h>
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#include <linux/ip.h>
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#include <linux/netdevice.h>
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#include <linux/if_tunnel.h>
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#include <linux/spinlock.h>
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#include <net/protocol.h>
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#include <net/gre.h>
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static const struct gre_protocol __rcu *gre_proto[GREPROTO_MAX] __read_mostly;
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static DEFINE_SPINLOCK(gre_proto_lock);
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struct gre_base_hdr {
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__be16 flags;
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__be16 protocol;
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};
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#define GRE_HEADER_SECTION 4
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int gre_add_protocol(const struct gre_protocol *proto, u8 version)
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{
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if (version >= GREPROTO_MAX)
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goto err_out;
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spin_lock(&gre_proto_lock);
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if (gre_proto[version])
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goto err_out_unlock;
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RCU_INIT_POINTER(gre_proto[version], proto);
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spin_unlock(&gre_proto_lock);
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return 0;
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err_out_unlock:
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spin_unlock(&gre_proto_lock);
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err_out:
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return -1;
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}
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EXPORT_SYMBOL_GPL(gre_add_protocol);
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int gre_del_protocol(const struct gre_protocol *proto, u8 version)
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{
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if (version >= GREPROTO_MAX)
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goto err_out;
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spin_lock(&gre_proto_lock);
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if (rcu_dereference_protected(gre_proto[version],
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lockdep_is_held(&gre_proto_lock)) != proto)
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goto err_out_unlock;
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RCU_INIT_POINTER(gre_proto[version], NULL);
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spin_unlock(&gre_proto_lock);
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synchronize_rcu();
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return 0;
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err_out_unlock:
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spin_unlock(&gre_proto_lock);
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err_out:
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return -1;
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}
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EXPORT_SYMBOL_GPL(gre_del_protocol);
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static int gre_rcv(struct sk_buff *skb)
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{
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const struct gre_protocol *proto;
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u8 ver;
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int ret;
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if (!pskb_may_pull(skb, 12))
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goto drop;
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ver = skb->data[1]&0x7f;
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if (ver >= GREPROTO_MAX)
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goto drop;
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rcu_read_lock();
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proto = rcu_dereference(gre_proto[ver]);
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if (!proto || !proto->handler)
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goto drop_unlock;
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ret = proto->handler(skb);
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rcu_read_unlock();
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return ret;
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drop_unlock:
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rcu_read_unlock();
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drop:
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kfree_skb(skb);
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return NET_RX_DROP;
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}
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static void gre_err(struct sk_buff *skb, u32 info)
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{
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const struct gre_protocol *proto;
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const struct iphdr *iph = (const struct iphdr *)skb->data;
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u8 ver = skb->data[(iph->ihl<<2) + 1]&0x7f;
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if (ver >= GREPROTO_MAX)
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return;
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rcu_read_lock();
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proto = rcu_dereference(gre_proto[ver]);
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if (proto && proto->err_handler)
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proto->err_handler(skb, info);
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rcu_read_unlock();
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}
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static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
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netdev_features_t features)
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{
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struct sk_buff *segs = ERR_PTR(-EINVAL);
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netdev_features_t enc_features;
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int ghl = GRE_HEADER_SECTION;
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struct gre_base_hdr *greh;
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int mac_len = skb->mac_len;
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int tnl_hlen;
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bool csum;
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if (unlikely(skb_shinfo(skb)->gso_type &
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~(SKB_GSO_TCPV4 |
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SKB_GSO_TCPV6 |
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SKB_GSO_UDP |
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SKB_GSO_DODGY |
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SKB_GSO_TCP_ECN |
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SKB_GSO_GRE)))
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goto out;
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if (unlikely(!pskb_may_pull(skb, sizeof(*greh))))
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goto out;
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greh = (struct gre_base_hdr *)skb_transport_header(skb);
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if (greh->flags & GRE_KEY)
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ghl += GRE_HEADER_SECTION;
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if (greh->flags & GRE_SEQ)
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ghl += GRE_HEADER_SECTION;
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if (greh->flags & GRE_CSUM) {
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ghl += GRE_HEADER_SECTION;
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csum = true;
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} else
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csum = false;
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/* setup inner skb. */
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if (greh->protocol == htons(ETH_P_TEB)) {
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struct ethhdr *eth = eth_hdr(skb);
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skb->protocol = eth->h_proto;
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} else {
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skb->protocol = greh->protocol;
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}
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skb->encapsulation = 0;
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if (unlikely(!pskb_may_pull(skb, ghl)))
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goto out;
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__skb_pull(skb, ghl);
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skb_reset_mac_header(skb);
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skb_set_network_header(skb, skb_inner_network_offset(skb));
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skb->mac_len = skb_inner_network_offset(skb);
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/* segment inner packet. */
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enc_features = skb->dev->hw_enc_features & netif_skb_features(skb);
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segs = skb_mac_gso_segment(skb, enc_features);
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if (!segs || IS_ERR(segs))
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goto out;
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skb = segs;
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tnl_hlen = skb_tnl_header_len(skb);
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do {
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__skb_push(skb, ghl);
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if (csum) {
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__be32 *pcsum;
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if (skb_has_shared_frag(skb)) {
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int err;
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err = __skb_linearize(skb);
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if (err) {
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kfree_skb(segs);
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segs = ERR_PTR(err);
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goto out;
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}
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}
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greh = (struct gre_base_hdr *)(skb->data);
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pcsum = (__be32 *)(greh + 1);
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*pcsum = 0;
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*(__sum16 *)pcsum = csum_fold(skb_checksum(skb, 0, skb->len, 0));
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}
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__skb_push(skb, tnl_hlen - ghl);
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skb_reset_mac_header(skb);
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skb_set_network_header(skb, mac_len);
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skb->mac_len = mac_len;
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} while ((skb = skb->next));
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out:
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return segs;
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}
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static int gre_gso_send_check(struct sk_buff *skb)
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{
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if (!skb->encapsulation)
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return -EINVAL;
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return 0;
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}
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static const struct net_protocol net_gre_protocol = {
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.handler = gre_rcv,
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.err_handler = gre_err,
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.netns_ok = 1,
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};
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static const struct net_offload gre_offload = {
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.callbacks = {
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.gso_send_check = gre_gso_send_check,
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.gso_segment = gre_gso_segment,
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},
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};
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static int __init gre_init(void)
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{
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pr_info("GRE over IPv4 demultiplexor driver\n");
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if (inet_add_protocol(&net_gre_protocol, IPPROTO_GRE) < 0) {
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pr_err("can't add protocol\n");
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return -EAGAIN;
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}
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if (inet_add_offload(&gre_offload, IPPROTO_GRE)) {
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pr_err("can't add protocol offload\n");
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inet_del_protocol(&net_gre_protocol, IPPROTO_GRE);
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return -EAGAIN;
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}
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return 0;
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}
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static void __exit gre_exit(void)
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{
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inet_del_offload(&gre_offload, IPPROTO_GRE);
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inet_del_protocol(&net_gre_protocol, IPPROTO_GRE);
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}
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module_init(gre_init);
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module_exit(gre_exit);
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MODULE_DESCRIPTION("GRE over IPv4 demultiplexer driver");
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MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)");
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MODULE_LICENSE("GPL");
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