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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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 | // SPDX-License-Identifier: GPL-2.0-only /* * Transparent proxy support for Linux/iptables * * Copyright (c) 2006-2010 BalaBit IT Ltd. * Author: Balazs Scheidler, Krisztian Kovacs */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/module.h> #include <linux/skbuff.h> #include <linux/ip.h> #include <net/checksum.h> #include <net/udp.h> #include <net/tcp.h> #include <net/inet_sock.h> #include <net/inet_hashtables.h> #include <linux/inetdevice.h> #include <linux/netfilter/x_tables.h> #include <linux/netfilter_ipv4/ip_tables.h> #include <net/netfilter/ipv4/nf_defrag_ipv4.h> #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) #define XT_TPROXY_HAVE_IPV6 1 #include <net/if_inet6.h> #include <net/addrconf.h> #include <net/inet6_hashtables.h> #include <linux/netfilter_ipv6/ip6_tables.h> #include <net/netfilter/ipv6/nf_defrag_ipv6.h> #endif #include <net/netfilter/nf_tproxy.h> #include <linux/netfilter/xt_TPROXY.h> static unsigned int tproxy_tg4(struct net *net, struct sk_buff *skb, __be32 laddr, __be16 lport, u_int32_t mark_mask, u_int32_t mark_value) { const struct iphdr *iph = ip_hdr(skb); struct udphdr _hdr, *hp; struct sock *sk; hp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_hdr), &_hdr); if (hp == NULL) return NF_DROP; /* check if there's an ongoing connection on the packet * addresses, this happens if the redirect already happened * and the current packet belongs to an already established * connection */ sk = nf_tproxy_get_sock_v4(net, skb, iph->protocol, iph->saddr, iph->daddr, hp->source, hp->dest, skb->dev, NF_TPROXY_LOOKUP_ESTABLISHED); laddr = nf_tproxy_laddr4(skb, laddr, iph->daddr); if (!lport) lport = hp->dest; /* UDP has no TCP_TIME_WAIT state, so we never enter here */ if (sk && sk->sk_state == TCP_TIME_WAIT) /* reopening a TIME_WAIT connection needs special handling */ sk = nf_tproxy_handle_time_wait4(net, skb, laddr, lport, sk); else if (!sk) /* no, there's no established connection, check if * there's a listener on the redirected addr/port */ sk = nf_tproxy_get_sock_v4(net, skb, iph->protocol, iph->saddr, laddr, hp->source, lport, skb->dev, NF_TPROXY_LOOKUP_LISTENER); /* NOTE: assign_sock consumes our sk reference */ if (sk && nf_tproxy_sk_is_transparent(sk)) { /* This should be in a separate target, but we don't do multiple targets on the same rule yet */ skb->mark = (skb->mark & ~mark_mask) ^ mark_value; nf_tproxy_assign_sock(skb, sk); return NF_ACCEPT; } return NF_DROP; } static unsigned int tproxy_tg4_v0(struct sk_buff *skb, const struct xt_action_param *par) { const struct xt_tproxy_target_info *tgi = par->targinfo; return tproxy_tg4(xt_net(par), skb, tgi->laddr, tgi->lport, tgi->mark_mask, tgi->mark_value); } static unsigned int tproxy_tg4_v1(struct sk_buff *skb, const struct xt_action_param *par) { const struct xt_tproxy_target_info_v1 *tgi = par->targinfo; return tproxy_tg4(xt_net(par), skb, tgi->laddr.ip, tgi->lport, tgi->mark_mask, tgi->mark_value); } #ifdef XT_TPROXY_HAVE_IPV6 static unsigned int tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par) { const struct ipv6hdr *iph = ipv6_hdr(skb); const struct xt_tproxy_target_info_v1 *tgi = par->targinfo; struct udphdr _hdr, *hp; struct sock *sk; const struct in6_addr *laddr; __be16 lport; int thoff = 0; int tproto; tproto = ipv6_find_hdr(skb, &thoff, -1, NULL, NULL); if (tproto < 0) return NF_DROP; hp = skb_header_pointer(skb, thoff, sizeof(_hdr), &_hdr); if (!hp) return NF_DROP; /* check if there's an ongoing connection on the packet * addresses, this happens if the redirect already happened * and the current packet belongs to an already established * connection */ sk = nf_tproxy_get_sock_v6(xt_net(par), skb, thoff, tproto, &iph->saddr, &iph->daddr, hp->source, hp->dest, xt_in(par), NF_TPROXY_LOOKUP_ESTABLISHED); laddr = nf_tproxy_laddr6(skb, &tgi->laddr.in6, &iph->daddr); lport = tgi->lport ? tgi->lport : hp->dest; /* UDP has no TCP_TIME_WAIT state, so we never enter here */ if (sk && sk->sk_state == TCP_TIME_WAIT) { const struct xt_tproxy_target_info_v1 *tgi = par->targinfo; /* reopening a TIME_WAIT connection needs special handling */ sk = nf_tproxy_handle_time_wait6(skb, tproto, thoff, xt_net(par), &tgi->laddr.in6, tgi->lport, sk); } else if (!sk) /* no there's no established connection, check if * there's a listener on the redirected addr/port */ sk = nf_tproxy_get_sock_v6(xt_net(par), skb, thoff, tproto, &iph->saddr, laddr, hp->source, lport, xt_in(par), NF_TPROXY_LOOKUP_LISTENER); /* NOTE: assign_sock consumes our sk reference */ if (sk && nf_tproxy_sk_is_transparent(sk)) { /* This should be in a separate target, but we don't do multiple targets on the same rule yet */ skb->mark = (skb->mark & ~tgi->mark_mask) ^ tgi->mark_value; nf_tproxy_assign_sock(skb, sk); return NF_ACCEPT; } return NF_DROP; } static int tproxy_tg6_check(const struct xt_tgchk_param *par) { const struct ip6t_ip6 *i = par->entryinfo; int err; err = nf_defrag_ipv6_enable(par->net); if (err) return err; if ((i->proto == IPPROTO_TCP || i->proto == IPPROTO_UDP) && !(i->invflags & IP6T_INV_PROTO)) return 0; pr_info_ratelimited("Can be used only with -p tcp or -p udp\n"); return -EINVAL; } static void tproxy_tg6_destroy(const struct xt_tgdtor_param *par) { nf_defrag_ipv6_disable(par->net); } #endif static int tproxy_tg4_check(const struct xt_tgchk_param *par) { const struct ipt_ip *i = par->entryinfo; int err; err = nf_defrag_ipv4_enable(par->net); if (err) return err; if ((i->proto == IPPROTO_TCP || i->proto == IPPROTO_UDP) && !(i->invflags & IPT_INV_PROTO)) return 0; pr_info_ratelimited("Can be used only with -p tcp or -p udp\n"); return -EINVAL; } static void tproxy_tg4_destroy(const struct xt_tgdtor_param *par) { nf_defrag_ipv4_disable(par->net); } static struct xt_target tproxy_tg_reg[] __read_mostly = { { .name = "TPROXY", .family = NFPROTO_IPV4, .table = "mangle", .target = tproxy_tg4_v0, .revision = 0, .targetsize = sizeof(struct xt_tproxy_target_info), .checkentry = tproxy_tg4_check, .destroy = tproxy_tg4_destroy, .hooks = 1 << NF_INET_PRE_ROUTING, .me = THIS_MODULE, }, { .name = "TPROXY", .family = NFPROTO_IPV4, .table = "mangle", .target = tproxy_tg4_v1, .revision = 1, .targetsize = sizeof(struct xt_tproxy_target_info_v1), .checkentry = tproxy_tg4_check, .destroy = tproxy_tg4_destroy, .hooks = 1 << NF_INET_PRE_ROUTING, .me = THIS_MODULE, }, #ifdef XT_TPROXY_HAVE_IPV6 { .name = "TPROXY", .family = NFPROTO_IPV6, .table = "mangle", .target = tproxy_tg6_v1, .revision = 1, .targetsize = sizeof(struct xt_tproxy_target_info_v1), .checkentry = tproxy_tg6_check, .destroy = tproxy_tg6_destroy, .hooks = 1 << NF_INET_PRE_ROUTING, .me = THIS_MODULE, }, #endif }; static int __init tproxy_tg_init(void) { return xt_register_targets(tproxy_tg_reg, ARRAY_SIZE(tproxy_tg_reg)); } static void __exit tproxy_tg_exit(void) { xt_unregister_targets(tproxy_tg_reg, ARRAY_SIZE(tproxy_tg_reg)); } module_init(tproxy_tg_init); module_exit(tproxy_tg_exit); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Balazs Scheidler, Krisztian Kovacs"); MODULE_DESCRIPTION("Netfilter transparent proxy (TPROXY) target module."); MODULE_ALIAS("ipt_TPROXY"); MODULE_ALIAS("ip6t_TPROXY"); |