145 lines
3.0 KiB
C
145 lines
3.0 KiB
C
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/*
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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/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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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 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 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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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_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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