1 /* 2 * ip_vs_nfct.c: Netfilter connection tracking support for IPVS 3 * 4 * Portions Copyright (C) 2001-2002 5 * Antefacto Ltd, 181 Parnell St, Dublin 1, Ireland. 6 * 7 * Portions Copyright (C) 2003-2010 8 * Julian Anastasov 9 * 10 * 11 * This code is free software; you can redistribute it and/or modify 12 * it under the terms of the GNU General Public License as published by 13 * the Free Software Foundation; either version 2 of the License, or 14 * (at your option) any later version. 15 * 16 * This program is distributed in the hope that it will be useful, 17 * but WITHOUT ANY WARRANTY; without even the implied warranty of 18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 19 * GNU General Public License for more details. 20 * 21 * You should have received a copy of the GNU General Public License 22 * along with this program; if not, see <http://www.gnu.org/licenses/>. 23 * 24 * 25 * Authors: 26 * Ben North <ben@redfrontdoor.org> 27 * Julian Anastasov <ja@ssi.bg> Reorganize and sync with latest kernels 28 * Hannes Eder <heder@google.com> Extend NFCT support for FTP, ipvs match 29 * 30 * 31 * Current status: 32 * 33 * - provide conntrack confirmation for new and related connections, by 34 * this way we can see their proper conntrack state in all hooks 35 * - support for all forwarding methods, not only NAT 36 * - FTP support (NAT), ability to support other NAT apps with expectations 37 * - to correctly create expectations for related NAT connections the proper 38 * NF conntrack support must be already installed, eg. ip_vs_ftp requires 39 * nf_conntrack_ftp ... iptables_nat for the same ports (but no iptables 40 * NAT rules are needed) 41 * - alter reply for NAT when forwarding packet in original direction: 42 * conntrack from client in NEW or RELATED (Passive FTP DATA) state or 43 * when RELATED conntrack is created from real server (Active FTP DATA) 44 * - if iptables_nat is not loaded the Passive FTP will not work (the 45 * PASV response can not be NAT-ed) but Active FTP should work 46 * 47 */ 48 49 #define KMSG_COMPONENT "IPVS" 50 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt 51 52 #include <linux/module.h> 53 #include <linux/types.h> 54 #include <linux/kernel.h> 55 #include <linux/errno.h> 56 #include <linux/compiler.h> 57 #include <linux/vmalloc.h> 58 #include <linux/skbuff.h> 59 #include <net/ip.h> 60 #include <linux/netfilter.h> 61 #include <linux/netfilter_ipv4.h> 62 #include <net/ip_vs.h> 63 #include <net/netfilter/nf_conntrack_core.h> 64 #include <net/netfilter/nf_conntrack_expect.h> 65 #include <net/netfilter/nf_conntrack_seqadj.h> 66 #include <net/netfilter/nf_conntrack_helper.h> 67 #include <net/netfilter/nf_conntrack_zones.h> 68 69 70 #define FMT_TUPLE "%pI4:%u->%pI4:%u/%u" 71 #define ARG_TUPLE(T) &(T)->src.u3.ip, ntohs((T)->src.u.all), \ 72 &(T)->dst.u3.ip, ntohs((T)->dst.u.all), \ 73 (T)->dst.protonum 74 75 #define FMT_CONN "%pI4:%u->%pI4:%u->%pI4:%u/%u:%u" 76 #define ARG_CONN(C) &((C)->caddr.ip), ntohs((C)->cport), \ 77 &((C)->vaddr.ip), ntohs((C)->vport), \ 78 &((C)->daddr.ip), ntohs((C)->dport), \ 79 (C)->protocol, (C)->state 80 81 void 82 ip_vs_update_conntrack(struct sk_buff *skb, struct ip_vs_conn *cp, int outin) 83 { 84 enum ip_conntrack_info ctinfo; 85 struct nf_conn *ct = nf_ct_get(skb, &ctinfo); 86 struct nf_conntrack_tuple new_tuple; 87 88 if (ct == NULL || nf_ct_is_confirmed(ct) || nf_ct_is_untracked(ct) || 89 nf_ct_is_dying(ct)) 90 return; 91 92 /* Never alter conntrack for non-NAT conns */ 93 if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ) 94 return; 95 96 /* Never alter conntrack for OPS conns (no reply is expected) */ 97 if (cp->flags & IP_VS_CONN_F_ONE_PACKET) 98 return; 99 100 /* Alter reply only in original direction */ 101 if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) 102 return; 103 104 /* Applications may adjust TCP seqs */ 105 if (cp->app && nf_ct_protonum(ct) == IPPROTO_TCP && 106 !nfct_seqadj(ct) && !nfct_seqadj_ext_add(ct)) 107 return; 108 109 /* 110 * The connection is not yet in the hashtable, so we update it. 111 * CIP->VIP will remain the same, so leave the tuple in 112 * IP_CT_DIR_ORIGINAL untouched. When the reply comes back from the 113 * real-server we will see RIP->DIP. 114 */ 115 new_tuple = ct->tuplehash[IP_CT_DIR_REPLY].tuple; 116 /* 117 * This will also take care of UDP and other protocols. 118 */ 119 if (outin) { 120 new_tuple.src.u3 = cp->daddr; 121 if (new_tuple.dst.protonum != IPPROTO_ICMP && 122 new_tuple.dst.protonum != IPPROTO_ICMPV6) 123 new_tuple.src.u.tcp.port = cp->dport; 124 } else { 125 new_tuple.dst.u3 = cp->vaddr; 126 if (new_tuple.dst.protonum != IPPROTO_ICMP && 127 new_tuple.dst.protonum != IPPROTO_ICMPV6) 128 new_tuple.dst.u.tcp.port = cp->vport; 129 } 130 IP_VS_DBG(7, "%s: Updating conntrack ct=%p, status=0x%lX, " 131 "ctinfo=%d, old reply=" FMT_TUPLE 132 ", new reply=" FMT_TUPLE ", cp=" FMT_CONN "\n", 133 __func__, ct, ct->status, ctinfo, 134 ARG_TUPLE(&ct->tuplehash[IP_CT_DIR_REPLY].tuple), 135 ARG_TUPLE(&new_tuple), ARG_CONN(cp)); 136 nf_conntrack_alter_reply(ct, &new_tuple); 137 } 138 139 int ip_vs_confirm_conntrack(struct sk_buff *skb) 140 { 141 return nf_conntrack_confirm(skb); 142 } 143 144 /* 145 * Called from init_conntrack() as expectfn handler. 146 */ 147 static void ip_vs_nfct_expect_callback(struct nf_conn *ct, 148 struct nf_conntrack_expect *exp) 149 { 150 struct nf_conntrack_tuple *orig, new_reply; 151 struct ip_vs_conn *cp; 152 struct ip_vs_conn_param p; 153 struct net *net = nf_ct_net(ct); 154 155 if (exp->tuple.src.l3num != PF_INET) 156 return; 157 158 /* 159 * We assume that no NF locks are held before this callback. 160 * ip_vs_conn_out_get and ip_vs_conn_in_get should match their 161 * expectations even if they use wildcard values, now we provide the 162 * actual values from the newly created original conntrack direction. 163 * The conntrack is confirmed when packet reaches IPVS hooks. 164 */ 165 166 /* RS->CLIENT */ 167 orig = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple; 168 ip_vs_conn_fill_param(net_ipvs(net), exp->tuple.src.l3num, orig->dst.protonum, 169 &orig->src.u3, orig->src.u.tcp.port, 170 &orig->dst.u3, orig->dst.u.tcp.port, &p); 171 cp = ip_vs_conn_out_get(&p); 172 if (cp) { 173 /* Change reply CLIENT->RS to CLIENT->VS */ 174 new_reply = ct->tuplehash[IP_CT_DIR_REPLY].tuple; 175 IP_VS_DBG(7, "%s: ct=%p, status=0x%lX, tuples=" FMT_TUPLE ", " 176 FMT_TUPLE ", found inout cp=" FMT_CONN "\n", 177 __func__, ct, ct->status, 178 ARG_TUPLE(orig), ARG_TUPLE(&new_reply), 179 ARG_CONN(cp)); 180 new_reply.dst.u3 = cp->vaddr; 181 new_reply.dst.u.tcp.port = cp->vport; 182 IP_VS_DBG(7, "%s: ct=%p, new tuples=" FMT_TUPLE ", " FMT_TUPLE 183 ", inout cp=" FMT_CONN "\n", 184 __func__, ct, 185 ARG_TUPLE(orig), ARG_TUPLE(&new_reply), 186 ARG_CONN(cp)); 187 goto alter; 188 } 189 190 /* CLIENT->VS */ 191 cp = ip_vs_conn_in_get(&p); 192 if (cp) { 193 /* Change reply VS->CLIENT to RS->CLIENT */ 194 new_reply = ct->tuplehash[IP_CT_DIR_REPLY].tuple; 195 IP_VS_DBG(7, "%s: ct=%p, status=0x%lX, tuples=" FMT_TUPLE ", " 196 FMT_TUPLE ", found outin cp=" FMT_CONN "\n", 197 __func__, ct, ct->status, 198 ARG_TUPLE(orig), ARG_TUPLE(&new_reply), 199 ARG_CONN(cp)); 200 new_reply.src.u3 = cp->daddr; 201 new_reply.src.u.tcp.port = cp->dport; 202 IP_VS_DBG(7, "%s: ct=%p, new tuples=" FMT_TUPLE ", " 203 FMT_TUPLE ", outin cp=" FMT_CONN "\n", 204 __func__, ct, 205 ARG_TUPLE(orig), ARG_TUPLE(&new_reply), 206 ARG_CONN(cp)); 207 goto alter; 208 } 209 210 IP_VS_DBG(7, "%s: ct=%p, status=0x%lX, tuple=" FMT_TUPLE 211 " - unknown expect\n", 212 __func__, ct, ct->status, ARG_TUPLE(orig)); 213 return; 214 215 alter: 216 /* Never alter conntrack for non-NAT conns */ 217 if (IP_VS_FWD_METHOD(cp) == IP_VS_CONN_F_MASQ) 218 nf_conntrack_alter_reply(ct, &new_reply); 219 ip_vs_conn_put(cp); 220 return; 221 } 222 223 /* 224 * Create NF conntrack expectation with wildcard (optional) source port. 225 * Then the default callback function will alter the reply and will confirm 226 * the conntrack entry when the first packet comes. 227 * Use port 0 to expect connection from any port. 228 */ 229 void ip_vs_nfct_expect_related(struct sk_buff *skb, struct nf_conn *ct, 230 struct ip_vs_conn *cp, u_int8_t proto, 231 const __be16 port, int from_rs) 232 { 233 struct nf_conntrack_expect *exp; 234 235 if (ct == NULL || nf_ct_is_untracked(ct)) 236 return; 237 238 exp = nf_ct_expect_alloc(ct); 239 if (!exp) 240 return; 241 242 nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, nf_ct_l3num(ct), 243 from_rs ? &cp->daddr : &cp->caddr, 244 from_rs ? &cp->caddr : &cp->vaddr, 245 proto, port ? &port : NULL, 246 from_rs ? &cp->cport : &cp->vport); 247 248 exp->expectfn = ip_vs_nfct_expect_callback; 249 250 IP_VS_DBG(7, "%s: ct=%p, expect tuple=" FMT_TUPLE "\n", 251 __func__, ct, ARG_TUPLE(&exp->tuple)); 252 nf_ct_expect_related(exp); 253 nf_ct_expect_put(exp); 254 } 255 EXPORT_SYMBOL(ip_vs_nfct_expect_related); 256 257 /* 258 * Our connection was terminated, try to drop the conntrack immediately 259 */ 260 void ip_vs_conn_drop_conntrack(struct ip_vs_conn *cp) 261 { 262 struct nf_conntrack_tuple_hash *h; 263 struct nf_conn *ct; 264 struct nf_conntrack_tuple tuple; 265 266 if (!cp->cport) 267 return; 268 269 tuple = (struct nf_conntrack_tuple) { 270 .dst = { .protonum = cp->protocol, .dir = IP_CT_DIR_ORIGINAL } }; 271 tuple.src.u3 = cp->caddr; 272 tuple.src.u.all = cp->cport; 273 tuple.src.l3num = cp->af; 274 tuple.dst.u3 = cp->vaddr; 275 tuple.dst.u.all = cp->vport; 276 277 IP_VS_DBG(7, "%s: dropping conntrack with tuple=" FMT_TUPLE 278 " for conn " FMT_CONN "\n", 279 __func__, ARG_TUPLE(&tuple), ARG_CONN(cp)); 280 281 h = nf_conntrack_find_get(cp->ipvs->net, &nf_ct_zone_dflt, &tuple); 282 if (h) { 283 ct = nf_ct_tuplehash_to_ctrack(h); 284 if (nf_ct_kill(ct)) { 285 IP_VS_DBG(7, "%s: ct=%p, deleted conntrack for tuple=" 286 FMT_TUPLE "\n", 287 __func__, ct, ARG_TUPLE(&tuple)); 288 } else { 289 IP_VS_DBG(7, "%s: ct=%p, no conntrack timer for tuple=" 290 FMT_TUPLE "\n", 291 __func__, ct, ARG_TUPLE(&tuple)); 292 } 293 nf_ct_put(ct); 294 } else { 295 IP_VS_DBG(7, "%s: no conntrack for tuple=" FMT_TUPLE "\n", 296 __func__, ARG_TUPLE(&tuple)); 297 } 298 } 299 300