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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 | /* IP tables module for matching the value of the IPv4 and TCP ECN bits * * (C) 2002 by Harald Welte <laforge@gnumonks.org> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include <linux/in.h> #include <linux/ip.h> #include <net/ip.h> #include <linux/module.h> #include <linux/skbuff.h> #include <linux/tcp.h> #include <linux/netfilter/x_tables.h> #include <linux/netfilter_ipv4/ip_tables.h> #include <linux/netfilter_ipv4/ipt_ecn.h> MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); MODULE_DESCRIPTION("iptables ECN matching module"); MODULE_LICENSE("GPL"); static inline int match_ip(const struct sk_buff *skb, const struct ipt_ecn_info *einfo) { return (ip_hdr(skb)->tos & IPT_ECN_IP_MASK) == einfo->ip_ect; } static inline int match_tcp(const struct sk_buff *skb, const struct ipt_ecn_info *einfo, int *hotdrop) { struct tcphdr _tcph, *th; /* In practice, TCP match does this, so can't fail. But let's * be good citizens. */ th = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_tcph), &_tcph); if (th == NULL) { *hotdrop = 0; return 0; } if (einfo->operation & IPT_ECN_OP_MATCH_ECE) { if (einfo->invert & IPT_ECN_OP_MATCH_ECE) { if (th->ece == 1) return 0; } else { if (th->ece == 0) return 0; } } if (einfo->operation & IPT_ECN_OP_MATCH_CWR) { if (einfo->invert & IPT_ECN_OP_MATCH_CWR) { if (th->cwr == 1) return 0; } else { if (th->cwr == 0) return 0; } } return 1; } static int match(const struct sk_buff *skb, const struct net_device *in, const struct net_device *out, const struct xt_match *match, const void *matchinfo, int offset, unsigned int protoff, int *hotdrop) { const struct ipt_ecn_info *info = matchinfo; if (info->operation & IPT_ECN_OP_MATCH_IP) if (!match_ip(skb, info)) return 0; if (info->operation & (IPT_ECN_OP_MATCH_ECE|IPT_ECN_OP_MATCH_CWR)) { if (ip_hdr(skb)->protocol != IPPROTO_TCP) return 0; if (!match_tcp(skb, info, hotdrop)) return 0; } return 1; } static int checkentry(const char *tablename, const void *ip_void, const struct xt_match *match, void *matchinfo, unsigned int hook_mask) { const struct ipt_ecn_info *info = matchinfo; const struct ipt_ip *ip = ip_void; if (info->operation & IPT_ECN_OP_MATCH_MASK) return 0; if (info->invert & IPT_ECN_OP_MATCH_MASK) return 0; if (info->operation & (IPT_ECN_OP_MATCH_ECE|IPT_ECN_OP_MATCH_CWR) && ip->proto != IPPROTO_TCP) { printk(KERN_WARNING "ipt_ecn: can't match TCP bits in rule for" " non-tcp packets\n"); return 0; } return 1; } static struct xt_match ecn_match = { .name = "ecn", .family = AF_INET, .match = match, .matchsize = sizeof(struct ipt_ecn_info), .checkentry = checkentry, .me = THIS_MODULE, }; static int __init ipt_ecn_init(void) { return xt_register_match(&ecn_match); } static void __exit ipt_ecn_fini(void) { xt_unregister_match(&ecn_match); } module_init(ipt_ecn_init); module_exit(ipt_ecn_fini); |