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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 | // SPDX-License-Identifier: GPL-2.0-only /* * This is the 1999 rewrite of IP Firewalling, aiming for kernel 2.3.x. * * Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling * Copyright (C) 2000-2004 Netfilter Core Team <coreteam@netfilter.org> */ #include <linux/module.h> #include <linux/netfilter_ipv4/ip_tables.h> #include <linux/netdevice.h> #include <linux/skbuff.h> #include <linux/slab.h> #include <net/sock.h> #include <net/route.h> #include <linux/ip.h> #include <net/ip.h> MODULE_LICENSE("GPL"); MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>"); MODULE_DESCRIPTION("iptables mangle table"); #define MANGLE_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | \ (1 << NF_INET_LOCAL_IN) | \ (1 << NF_INET_FORWARD) | \ (1 << NF_INET_LOCAL_OUT) | \ (1 << NF_INET_POST_ROUTING)) static const struct xt_table packet_mangler = { .name = "mangle", .valid_hooks = MANGLE_VALID_HOOKS, .me = THIS_MODULE, .af = NFPROTO_IPV4, .priority = NF_IP_PRI_MANGLE, }; static unsigned int ipt_mangle_out(void *priv, struct sk_buff *skb, const struct nf_hook_state *state) { unsigned int ret, verdict; const struct iphdr *iph; __be32 saddr, daddr; u32 mark; int err; u8 tos; /* Save things which could affect route */ mark = skb->mark; iph = ip_hdr(skb); saddr = iph->saddr; daddr = iph->daddr; tos = iph->tos; ret = ipt_do_table(priv, skb, state); verdict = ret & NF_VERDICT_MASK; /* Reroute for ANY change. */ if (verdict != NF_DROP && verdict != NF_STOLEN) { iph = ip_hdr(skb); if (iph->saddr != saddr || iph->daddr != daddr || skb->mark != mark || iph->tos != tos) { err = ip_route_me_harder(state->net, state->sk, skb, RTN_UNSPEC); if (err < 0) ret = NF_DROP_ERR(err); } } return ret; } /* The work comes in here from netfilter.c. */ static unsigned int iptable_mangle_hook(void *priv, struct sk_buff *skb, const struct nf_hook_state *state) { if (state->hook == NF_INET_LOCAL_OUT) return ipt_mangle_out(priv, skb, state); return ipt_do_table(priv, skb, state); } static struct nf_hook_ops *mangle_ops __read_mostly; static int iptable_mangle_table_init(struct net *net) { struct ipt_replace *repl; int ret; repl = ipt_alloc_initial_table(&packet_mangler); if (repl == NULL) return -ENOMEM; ret = ipt_register_table(net, &packet_mangler, repl, mangle_ops); kfree(repl); return ret; } static void __net_exit iptable_mangle_net_pre_exit(struct net *net) { ipt_unregister_table_pre_exit(net, "mangle"); } static void __net_exit iptable_mangle_net_exit(struct net *net) { ipt_unregister_table_exit(net, "mangle"); } static struct pernet_operations iptable_mangle_net_ops = { .pre_exit = iptable_mangle_net_pre_exit, .exit = iptable_mangle_net_exit, }; static int __init iptable_mangle_init(void) { int ret = xt_register_template(&packet_mangler, iptable_mangle_table_init); if (ret < 0) return ret; mangle_ops = xt_hook_ops_alloc(&packet_mangler, iptable_mangle_hook); if (IS_ERR(mangle_ops)) { xt_unregister_template(&packet_mangler); ret = PTR_ERR(mangle_ops); return ret; } ret = register_pernet_subsys(&iptable_mangle_net_ops); if (ret < 0) { xt_unregister_template(&packet_mangler); kfree(mangle_ops); return ret; } return ret; } static void __exit iptable_mangle_fini(void) { unregister_pernet_subsys(&iptable_mangle_net_ops); xt_unregister_template(&packet_mangler); kfree(mangle_ops); } module_init(iptable_mangle_init); module_exit(iptable_mangle_fini); |