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![Florian Westphal](/assets/img/avatar_default.png)
currently aliased to try_module_get/_put. Will be changed in next patch when we add functions to make use of ->net argument to store usercount per l3proto tracker. This is needed to avoid registering the conntrack hooks in all netns and later only enable connection tracking in those that need conntrack. Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
331 lines
9.6 KiB
C
331 lines
9.6 KiB
C
/*
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* xt_conntrack - Netfilter module to match connection tracking
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* information. (Superset of Rusty's minimalistic state match.)
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*
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* (C) 2001 Marc Boucher (marc@mbsi.ca).
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* (C) 2006-2012 Patrick McHardy <kaber@trash.net>
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* Copyright © CC Computer Consultants GmbH, 2007 - 2008
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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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/skbuff.h>
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#include <net/ipv6.h>
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#include <linux/netfilter/x_tables.h>
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#include <linux/netfilter/xt_conntrack.h>
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#include <net/netfilter/nf_conntrack.h>
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>");
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MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
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MODULE_DESCRIPTION("Xtables: connection tracking state match");
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MODULE_ALIAS("ipt_conntrack");
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MODULE_ALIAS("ip6t_conntrack");
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static bool
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conntrack_addrcmp(const union nf_inet_addr *kaddr,
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const union nf_inet_addr *uaddr,
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const union nf_inet_addr *umask, unsigned int l3proto)
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{
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if (l3proto == NFPROTO_IPV4)
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return ((kaddr->ip ^ uaddr->ip) & umask->ip) == 0;
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else if (l3proto == NFPROTO_IPV6)
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return ipv6_masked_addr_cmp(&kaddr->in6, &umask->in6,
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&uaddr->in6) == 0;
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else
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return false;
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}
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static inline bool
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conntrack_mt_origsrc(const struct nf_conn *ct,
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const struct xt_conntrack_mtinfo2 *info,
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u_int8_t family)
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{
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return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3,
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&info->origsrc_addr, &info->origsrc_mask, family);
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}
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static inline bool
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conntrack_mt_origdst(const struct nf_conn *ct,
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const struct xt_conntrack_mtinfo2 *info,
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u_int8_t family)
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{
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return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3,
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&info->origdst_addr, &info->origdst_mask, family);
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}
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static inline bool
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conntrack_mt_replsrc(const struct nf_conn *ct,
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const struct xt_conntrack_mtinfo2 *info,
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u_int8_t family)
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{
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return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3,
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&info->replsrc_addr, &info->replsrc_mask, family);
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}
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static inline bool
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conntrack_mt_repldst(const struct nf_conn *ct,
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const struct xt_conntrack_mtinfo2 *info,
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u_int8_t family)
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{
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return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3,
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&info->repldst_addr, &info->repldst_mask, family);
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}
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static inline bool
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ct_proto_port_check(const struct xt_conntrack_mtinfo2 *info,
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const struct nf_conn *ct)
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{
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const struct nf_conntrack_tuple *tuple;
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tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
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if ((info->match_flags & XT_CONNTRACK_PROTO) &&
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(nf_ct_protonum(ct) == info->l4proto) ^
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!(info->invert_flags & XT_CONNTRACK_PROTO))
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return false;
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/* Shortcut to match all recognized protocols by using ->src.all. */
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if ((info->match_flags & XT_CONNTRACK_ORIGSRC_PORT) &&
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(tuple->src.u.all == info->origsrc_port) ^
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!(info->invert_flags & XT_CONNTRACK_ORIGSRC_PORT))
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return false;
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if ((info->match_flags & XT_CONNTRACK_ORIGDST_PORT) &&
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(tuple->dst.u.all == info->origdst_port) ^
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!(info->invert_flags & XT_CONNTRACK_ORIGDST_PORT))
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return false;
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tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
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if ((info->match_flags & XT_CONNTRACK_REPLSRC_PORT) &&
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(tuple->src.u.all == info->replsrc_port) ^
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!(info->invert_flags & XT_CONNTRACK_REPLSRC_PORT))
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return false;
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if ((info->match_flags & XT_CONNTRACK_REPLDST_PORT) &&
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(tuple->dst.u.all == info->repldst_port) ^
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!(info->invert_flags & XT_CONNTRACK_REPLDST_PORT))
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return false;
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return true;
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}
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static inline bool
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port_match(u16 min, u16 max, u16 port, bool invert)
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{
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return (port >= min && port <= max) ^ invert;
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}
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static inline bool
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ct_proto_port_check_v3(const struct xt_conntrack_mtinfo3 *info,
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const struct nf_conn *ct)
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{
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const struct nf_conntrack_tuple *tuple;
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tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
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if ((info->match_flags & XT_CONNTRACK_PROTO) &&
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(nf_ct_protonum(ct) == info->l4proto) ^
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!(info->invert_flags & XT_CONNTRACK_PROTO))
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return false;
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/* Shortcut to match all recognized protocols by using ->src.all. */
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if ((info->match_flags & XT_CONNTRACK_ORIGSRC_PORT) &&
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!port_match(info->origsrc_port, info->origsrc_port_high,
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ntohs(tuple->src.u.all),
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info->invert_flags & XT_CONNTRACK_ORIGSRC_PORT))
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return false;
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if ((info->match_flags & XT_CONNTRACK_ORIGDST_PORT) &&
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!port_match(info->origdst_port, info->origdst_port_high,
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ntohs(tuple->dst.u.all),
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info->invert_flags & XT_CONNTRACK_ORIGDST_PORT))
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return false;
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tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
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if ((info->match_flags & XT_CONNTRACK_REPLSRC_PORT) &&
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!port_match(info->replsrc_port, info->replsrc_port_high,
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ntohs(tuple->src.u.all),
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info->invert_flags & XT_CONNTRACK_REPLSRC_PORT))
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return false;
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if ((info->match_flags & XT_CONNTRACK_REPLDST_PORT) &&
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!port_match(info->repldst_port, info->repldst_port_high,
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ntohs(tuple->dst.u.all),
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info->invert_flags & XT_CONNTRACK_REPLDST_PORT))
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return false;
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return true;
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}
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static bool
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conntrack_mt(const struct sk_buff *skb, struct xt_action_param *par,
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u16 state_mask, u16 status_mask)
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{
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const struct xt_conntrack_mtinfo2 *info = par->matchinfo;
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enum ip_conntrack_info ctinfo;
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const struct nf_conn *ct;
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unsigned int statebit;
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ct = nf_ct_get(skb, &ctinfo);
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if (ct) {
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if (nf_ct_is_untracked(ct))
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statebit = XT_CONNTRACK_STATE_UNTRACKED;
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else
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statebit = XT_CONNTRACK_STATE_BIT(ctinfo);
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} else
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statebit = XT_CONNTRACK_STATE_INVALID;
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if (info->match_flags & XT_CONNTRACK_STATE) {
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if (ct != NULL) {
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if (test_bit(IPS_SRC_NAT_BIT, &ct->status))
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statebit |= XT_CONNTRACK_STATE_SNAT;
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if (test_bit(IPS_DST_NAT_BIT, &ct->status))
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statebit |= XT_CONNTRACK_STATE_DNAT;
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}
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if (!!(state_mask & statebit) ^
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!(info->invert_flags & XT_CONNTRACK_STATE))
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return false;
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}
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if (ct == NULL)
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return info->match_flags & XT_CONNTRACK_STATE;
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if ((info->match_flags & XT_CONNTRACK_DIRECTION) &&
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(CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) ^
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!(info->invert_flags & XT_CONNTRACK_DIRECTION))
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return false;
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if (info->match_flags & XT_CONNTRACK_ORIGSRC)
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if (conntrack_mt_origsrc(ct, info, xt_family(par)) ^
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!(info->invert_flags & XT_CONNTRACK_ORIGSRC))
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return false;
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if (info->match_flags & XT_CONNTRACK_ORIGDST)
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if (conntrack_mt_origdst(ct, info, xt_family(par)) ^
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!(info->invert_flags & XT_CONNTRACK_ORIGDST))
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return false;
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if (info->match_flags & XT_CONNTRACK_REPLSRC)
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if (conntrack_mt_replsrc(ct, info, xt_family(par)) ^
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!(info->invert_flags & XT_CONNTRACK_REPLSRC))
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return false;
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if (info->match_flags & XT_CONNTRACK_REPLDST)
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if (conntrack_mt_repldst(ct, info, xt_family(par)) ^
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!(info->invert_flags & XT_CONNTRACK_REPLDST))
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return false;
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if (par->match->revision != 3) {
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if (!ct_proto_port_check(info, ct))
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return false;
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} else {
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if (!ct_proto_port_check_v3(par->matchinfo, ct))
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return false;
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}
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if ((info->match_flags & XT_CONNTRACK_STATUS) &&
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(!!(status_mask & ct->status) ^
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!(info->invert_flags & XT_CONNTRACK_STATUS)))
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return false;
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if (info->match_flags & XT_CONNTRACK_EXPIRES) {
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unsigned long expires = nf_ct_expires(ct) / HZ;
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if ((expires >= info->expires_min &&
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expires <= info->expires_max) ^
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!(info->invert_flags & XT_CONNTRACK_EXPIRES))
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return false;
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}
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return true;
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}
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static bool
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conntrack_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
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{
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const struct xt_conntrack_mtinfo1 *info = par->matchinfo;
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return conntrack_mt(skb, par, info->state_mask, info->status_mask);
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}
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static bool
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conntrack_mt_v2(const struct sk_buff *skb, struct xt_action_param *par)
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{
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const struct xt_conntrack_mtinfo2 *info = par->matchinfo;
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return conntrack_mt(skb, par, info->state_mask, info->status_mask);
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}
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static bool
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conntrack_mt_v3(const struct sk_buff *skb, struct xt_action_param *par)
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{
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const struct xt_conntrack_mtinfo3 *info = par->matchinfo;
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return conntrack_mt(skb, par, info->state_mask, info->status_mask);
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}
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static int conntrack_mt_check(const struct xt_mtchk_param *par)
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{
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int ret;
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ret = nf_ct_netns_get(par->net, par->family);
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if (ret < 0)
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pr_info("cannot load conntrack support for proto=%u\n",
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par->family);
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return ret;
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}
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static void conntrack_mt_destroy(const struct xt_mtdtor_param *par)
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{
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nf_ct_netns_put(par->net, par->family);
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}
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static struct xt_match conntrack_mt_reg[] __read_mostly = {
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{
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.name = "conntrack",
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.revision = 1,
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.family = NFPROTO_UNSPEC,
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.matchsize = sizeof(struct xt_conntrack_mtinfo1),
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.match = conntrack_mt_v1,
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.checkentry = conntrack_mt_check,
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.destroy = conntrack_mt_destroy,
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.me = THIS_MODULE,
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},
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{
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.name = "conntrack",
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.revision = 2,
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.family = NFPROTO_UNSPEC,
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.matchsize = sizeof(struct xt_conntrack_mtinfo2),
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.match = conntrack_mt_v2,
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.checkentry = conntrack_mt_check,
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.destroy = conntrack_mt_destroy,
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.me = THIS_MODULE,
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},
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{
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.name = "conntrack",
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.revision = 3,
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.family = NFPROTO_UNSPEC,
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.matchsize = sizeof(struct xt_conntrack_mtinfo3),
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.match = conntrack_mt_v3,
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.checkentry = conntrack_mt_check,
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.destroy = conntrack_mt_destroy,
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.me = THIS_MODULE,
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},
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};
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static int __init conntrack_mt_init(void)
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{
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return xt_register_matches(conntrack_mt_reg,
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ARRAY_SIZE(conntrack_mt_reg));
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}
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static void __exit conntrack_mt_exit(void)
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{
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xt_unregister_matches(conntrack_mt_reg, ARRAY_SIZE(conntrack_mt_reg));
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}
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module_init(conntrack_mt_init);
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module_exit(conntrack_mt_exit);
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