| 1 | // SPDX-License-Identifier: GPL-2.0-only |
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| 2 | /* Kernel module to match connection tracking information. */ |
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| 3 | |
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| 4 | /* (C) 1999-2001 Paul `Rusty' Russell |
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| 5 | * (C) 2002-2005 Netfilter Core Team <coreteam@netfilter.org> |
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| 6 | */ |
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| 7 | |
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| 8 | #include <linux/module.h> |
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| 9 | #include <linux/skbuff.h> |
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| 10 | #include <net/netfilter/nf_conntrack.h> |
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| 11 | #include <linux/netfilter/x_tables.h> |
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| 12 | #include <linux/netfilter/xt_state.h> |
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| 13 | |
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| 14 | MODULE_LICENSE("GPL" ); |
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| 15 | MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>" ); |
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| 16 | MODULE_DESCRIPTION("ip[6]_tables connection tracking state match module" ); |
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| 17 | MODULE_ALIAS("ipt_state" ); |
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| 18 | MODULE_ALIAS("ip6t_state" ); |
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| 19 | |
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| 20 | static bool |
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| 21 | state_mt(const struct sk_buff *skb, struct xt_action_param *par) |
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| 22 | { |
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| 23 | const struct xt_state_info *sinfo = par->matchinfo; |
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| 24 | enum ip_conntrack_info ctinfo; |
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| 25 | unsigned int statebit; |
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| 26 | struct nf_conn *ct = nf_ct_get(skb, ctinfo: &ctinfo); |
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| 27 | |
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| 28 | if (ct) |
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| 29 | statebit = XT_STATE_BIT(ctinfo); |
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| 30 | else if (ctinfo == IP_CT_UNTRACKED) |
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| 31 | statebit = XT_STATE_UNTRACKED; |
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| 32 | else |
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| 33 | statebit = XT_STATE_INVALID; |
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| 34 | |
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| 35 | return (sinfo->statemask & statebit); |
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| 36 | } |
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| 37 | |
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| 38 | static int state_mt_check(const struct xt_mtchk_param *par) |
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| 39 | { |
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| 40 | int ret; |
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| 41 | |
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| 42 | ret = nf_ct_netns_get(net: par->net, nfproto: par->family); |
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| 43 | if (ret < 0) |
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| 44 | pr_info_ratelimited("cannot load conntrack support for proto=%u\n" , |
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| 45 | par->family); |
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| 46 | return ret; |
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| 47 | } |
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| 48 | |
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| 49 | static void state_mt_destroy(const struct xt_mtdtor_param *par) |
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| 50 | { |
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| 51 | nf_ct_netns_put(net: par->net, nfproto: par->family); |
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| 52 | } |
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| 53 | |
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| 54 | static struct xt_match state_mt_reg __read_mostly = { |
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| 55 | .name = "state" , |
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| 56 | .family = NFPROTO_UNSPEC, |
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| 57 | .checkentry = state_mt_check, |
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| 58 | .match = state_mt, |
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| 59 | .destroy = state_mt_destroy, |
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| 60 | .matchsize = sizeof(struct xt_state_info), |
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| 61 | .me = THIS_MODULE, |
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| 62 | }; |
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| 63 | |
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| 64 | static int __init state_mt_init(void) |
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| 65 | { |
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| 66 | return xt_register_match(target: &state_mt_reg); |
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| 67 | } |
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| 68 | |
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| 69 | static void __exit state_mt_exit(void) |
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| 70 | { |
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| 71 | xt_unregister_match(target: &state_mt_reg); |
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| 72 | } |
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| 73 | |
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| 74 | module_init(state_mt_init); |
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| 75 | module_exit(state_mt_exit); |
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| 76 | |
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