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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 | /* * GRE over IPv4 demultiplexer driver * * Authors: Dmitry Kozlov (xeb@mail.ru) * * 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. * */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/module.h> #include <linux/if.h> #include <linux/icmp.h> #include <linux/kernel.h> #include <linux/kmod.h> #include <linux/skbuff.h> #include <linux/in.h> #include <linux/ip.h> #include <linux/netdevice.h> #include <linux/if_tunnel.h> #include <linux/spinlock.h> #include <net/protocol.h> #include <net/gre.h> #include <net/icmp.h> #include <net/route.h> #include <net/xfrm.h> static const struct gre_protocol __rcu *gre_proto[GREPROTO_MAX] __read_mostly; int gre_add_protocol(const struct gre_protocol *proto, u8 version) { if (version >= GREPROTO_MAX) return -EINVAL; return (cmpxchg((const struct gre_protocol **)&gre_proto[version], NULL, proto) == NULL) ? 0 : -EBUSY; } EXPORT_SYMBOL_GPL(gre_add_protocol); int gre_del_protocol(const struct gre_protocol *proto, u8 version) { int ret; if (version >= GREPROTO_MAX) return -EINVAL; ret = (cmpxchg((const struct gre_protocol **)&gre_proto[version], proto, NULL) == proto) ? 0 : -EBUSY; if (ret) return ret; synchronize_rcu(); return 0; } EXPORT_SYMBOL_GPL(gre_del_protocol); static int gre_rcv(struct sk_buff *skb) { const struct gre_protocol *proto; u8 ver; int ret; if (!pskb_may_pull(skb, 12)) goto drop; ver = skb->data[1]&0x7f; if (ver >= GREPROTO_MAX) goto drop; rcu_read_lock(); proto = rcu_dereference(gre_proto[ver]); if (!proto || !proto->handler) goto drop_unlock; ret = proto->handler(skb); rcu_read_unlock(); return ret; drop_unlock: rcu_read_unlock(); drop: kfree_skb(skb); return NET_RX_DROP; } static void gre_err(struct sk_buff *skb, u32 info) { const struct gre_protocol *proto; const struct iphdr *iph = (const struct iphdr *)skb->data; u8 ver = skb->data[(iph->ihl<<2) + 1]&0x7f; if (ver >= GREPROTO_MAX) return; rcu_read_lock(); proto = rcu_dereference(gre_proto[ver]); if (proto && proto->err_handler) proto->err_handler(skb, info); rcu_read_unlock(); } static const struct net_protocol net_gre_protocol = { .handler = gre_rcv, .err_handler = gre_err, .netns_ok = 1, }; static int __init gre_init(void) { pr_info("GRE over IPv4 demultiplexor driver\n"); if (inet_add_protocol(&net_gre_protocol, IPPROTO_GRE) < 0) { pr_err("can't add protocol\n"); return -EAGAIN; } return 0; } static void __exit gre_exit(void) { inet_del_protocol(&net_gre_protocol, IPPROTO_GRE); } module_init(gre_init); module_exit(gre_exit); MODULE_DESCRIPTION("GRE over IPv4 demultiplexer driver"); MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)"); MODULE_LICENSE("GPL"); |