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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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 | // SPDX-License-Identifier: GPL-2.0-only /* * Xtables module for matching the value of the IPv4/IPv6 and TCP ECN bits * * (C) 2002 by Harald Welte <laforge@gnumonks.org> * (C) 2011 Patrick McHardy <kaber@trash.net> */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #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/xt_ecn.h> #include <linux/netfilter_ipv4/ip_tables.h> #include <linux/netfilter_ipv6/ip6_tables.h> MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); MODULE_DESCRIPTION("Xtables: Explicit Congestion Notification (ECN) flag match"); MODULE_LICENSE("GPL"); MODULE_ALIAS("ipt_ecn"); MODULE_ALIAS("ip6t_ecn"); static bool match_tcp(const struct sk_buff *skb, struct xt_action_param *par) { const struct xt_ecn_info *einfo = par->matchinfo; struct tcphdr _tcph; const struct tcphdr *th; /* In practice, TCP match does this, so can't fail. But let's * be good citizens. */ th = skb_header_pointer(skb, par->thoff, sizeof(_tcph), &_tcph); if (th == NULL) return false; if (einfo->operation & XT_ECN_OP_MATCH_ECE) { if (einfo->invert & XT_ECN_OP_MATCH_ECE) { if (th->ece == 1) return false; } else { if (th->ece == 0) return false; } } if (einfo->operation & XT_ECN_OP_MATCH_CWR) { if (einfo->invert & XT_ECN_OP_MATCH_CWR) { if (th->cwr == 1) return false; } else { if (th->cwr == 0) return false; } } return true; } static inline bool match_ip(const struct sk_buff *skb, const struct xt_ecn_info *einfo) { return ((ip_hdr(skb)->tos & XT_ECN_IP_MASK) == einfo->ip_ect) ^ !!(einfo->invert & XT_ECN_OP_MATCH_IP); } static bool ecn_mt4(const struct sk_buff *skb, struct xt_action_param *par) { const struct xt_ecn_info *info = par->matchinfo; if (info->operation & XT_ECN_OP_MATCH_IP && !match_ip(skb, info)) return false; if (info->operation & (XT_ECN_OP_MATCH_ECE | XT_ECN_OP_MATCH_CWR) && !match_tcp(skb, par)) return false; return true; } static int ecn_mt_check4(const struct xt_mtchk_param *par) { const struct xt_ecn_info *info = par->matchinfo; const struct ipt_ip *ip = par->entryinfo; if (info->operation & XT_ECN_OP_MATCH_MASK) return -EINVAL; if (info->invert & XT_ECN_OP_MATCH_MASK) return -EINVAL; if (info->operation & (XT_ECN_OP_MATCH_ECE | XT_ECN_OP_MATCH_CWR) && (ip->proto != IPPROTO_TCP || ip->invflags & IPT_INV_PROTO)) { pr_info_ratelimited("cannot match TCP bits for non-tcp packets\n"); return -EINVAL; } return 0; } static inline bool match_ipv6(const struct sk_buff *skb, const struct xt_ecn_info *einfo) { return (((ipv6_hdr(skb)->flow_lbl[0] >> 4) & XT_ECN_IP_MASK) == einfo->ip_ect) ^ !!(einfo->invert & XT_ECN_OP_MATCH_IP); } static bool ecn_mt6(const struct sk_buff *skb, struct xt_action_param *par) { const struct xt_ecn_info *info = par->matchinfo; if (info->operation & XT_ECN_OP_MATCH_IP && !match_ipv6(skb, info)) return false; if (info->operation & (XT_ECN_OP_MATCH_ECE | XT_ECN_OP_MATCH_CWR) && !match_tcp(skb, par)) return false; return true; } static int ecn_mt_check6(const struct xt_mtchk_param *par) { const struct xt_ecn_info *info = par->matchinfo; const struct ip6t_ip6 *ip = par->entryinfo; if (info->operation & XT_ECN_OP_MATCH_MASK) return -EINVAL; if (info->invert & XT_ECN_OP_MATCH_MASK) return -EINVAL; if (info->operation & (XT_ECN_OP_MATCH_ECE | XT_ECN_OP_MATCH_CWR) && (ip->proto != IPPROTO_TCP || ip->invflags & IP6T_INV_PROTO)) { pr_info_ratelimited("cannot match TCP bits for non-tcp packets\n"); return -EINVAL; } return 0; } static struct xt_match ecn_mt_reg[] __read_mostly = { { .name = "ecn", .family = NFPROTO_IPV4, .match = ecn_mt4, .matchsize = sizeof(struct xt_ecn_info), .checkentry = ecn_mt_check4, .me = THIS_MODULE, }, { .name = "ecn", .family = NFPROTO_IPV6, .match = ecn_mt6, .matchsize = sizeof(struct xt_ecn_info), .checkentry = ecn_mt_check6, .me = THIS_MODULE, }, }; static int __init ecn_mt_init(void) { return xt_register_matches(ecn_mt_reg, ARRAY_SIZE(ecn_mt_reg)); } static void __exit ecn_mt_exit(void) { xt_unregister_matches(ecn_mt_reg, ARRAY_SIZE(ecn_mt_reg)); } module_init(ecn_mt_init); module_exit(ecn_mt_exit); |