net/netfilter/ipvs/ip_vs_nfct.c

   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_helper.h>
  66 #include <net/netfilter/nf_conntrack_zones.h>
  67
  68
  69 #define FMT_TUPLE       "%pI4:%u->%pI4:%u/%u"
  70 #define ARG_TUPLE(T)    &(T)->src.u3.ip, ntohs((T)->src.u.all), \
  71                         &(T)->dst.u3.ip, ntohs((T)->dst.u.all), \
  72                         (T)->dst.protonum
  73
  74 #define FMT_CONN        "%pI4:%u->%pI4:%u->%pI4:%u/%u:%u"
  75 #define ARG_CONN(C)     &((C)->caddr.ip), ntohs((C)->cport), \
  76                         &((C)->vaddr.ip), ntohs((C)->vport), \
  77                         &((C)->daddr.ip), ntohs((C)->dport), \
  78                         (C)->protocol, (C)->state
  79
  80 void
  81 ip_vs_update_conntrack(struct sk_buff *skb, struct ip_vs_conn *cp, int outin)
  82 {
  83         enum ip_conntrack_info ctinfo;
  84         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
  85         struct nf_conntrack_tuple new_tuple;
  86
  87         if (ct == NULL || nf_ct_is_confirmed(ct) || nf_ct_is_untracked(ct) ||
  88             nf_ct_is_dying(ct))
  89                 return;
  90
  91         /* Never alter conntrack for non-NAT conns */
  92         if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ)
  93                 return;
  94
  95         /* Alter reply only in original direction */
  96         if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL)
  97                 return;
  98
  99         /*
 100          * The connection is not yet in the hashtable, so we update it.
 101          * CIP->VIP will remain the same, so leave the tuple in
 102          * IP_CT_DIR_ORIGINAL untouched.  When the reply comes back from the
 103          * real-server we will see RIP->DIP.
 104          */
 105         new_tuple = ct->tuplehash[IP_CT_DIR_REPLY].tuple;
 106         /*
 107          * This will also take care of UDP and other protocols.
 108          */
 109         if (outin) {
 110                 new_tuple.src.u3 = cp->daddr;
 111                 if (new_tuple.dst.protonum != IPPROTO_ICMP &&
 112                     new_tuple.dst.protonum != IPPROTO_ICMPV6)
 113                         new_tuple.src.u.tcp.port = cp->dport;
 114         } else {
 115                 new_tuple.dst.u3 = cp->vaddr;
 116                 if (new_tuple.dst.protonum != IPPROTO_ICMP &&
 117                     new_tuple.dst.protonum != IPPROTO_ICMPV6)
 118                         new_tuple.dst.u.tcp.port = cp->vport;
 119         }
 120         IP_VS_DBG(7, "%s: Updating conntrack ct=%p, status=0x%lX, "
 121                   "ctinfo=%d, old reply=" FMT_TUPLE
 122                   ", new reply=" FMT_TUPLE ", cp=" FMT_CONN "\n",
 123                   __func__, ct, ct->status, ctinfo,
 124                   ARG_TUPLE(&ct->tuplehash[IP_CT_DIR_REPLY].tuple),
 125                   ARG_TUPLE(&new_tuple), ARG_CONN(cp));
 126         nf_conntrack_alter_reply(ct, &new_tuple);
 127 }
 128
 129 int ip_vs_confirm_conntrack(struct sk_buff *skb)
 130 {
 131         return nf_conntrack_confirm(skb);
 132 }
 133
 134 /*
 135  * Called from init_conntrack() as expectfn handler.
 136  */
 137 static void ip_vs_nfct_expect_callback(struct nf_conn *ct,
 138         struct nf_conntrack_expect *exp)
 139 {
 140         struct nf_conntrack_tuple *orig, new_reply;
 141         struct ip_vs_conn *cp;
 142         struct ip_vs_conn_param p;
 143         struct net *net = nf_ct_net(ct);
 144
 145         if (exp->tuple.src.l3num != PF_INET)
 146                 return;
 147
 148         /*
 149          * We assume that no NF locks are held before this callback.
 150          * ip_vs_conn_out_get and ip_vs_conn_in_get should match their
 151          * expectations even if they use wildcard values, now we provide the
 152          * actual values from the newly created original conntrack direction.
 153          * The conntrack is confirmed when packet reaches IPVS hooks.
 154          */
 155
 156         /* RS->CLIENT */
 157         orig = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
 158         ip_vs_conn_fill_param(net, exp->tuple.src.l3num, orig->dst.protonum,
 159                               &orig->src.u3, orig->src.u.tcp.port,
 160                               &orig->dst.u3, orig->dst.u.tcp.port, &p);
 161         cp = ip_vs_conn_out_get(&p);
 162         if (cp) {
 163                 /* Change reply CLIENT->RS to CLIENT->VS */
 164                 new_reply = ct->tuplehash[IP_CT_DIR_REPLY].tuple;
 165                 IP_VS_DBG(7, "%s: ct=%p, status=0x%lX, tuples=" FMT_TUPLE ", "
 166                           FMT_TUPLE ", found inout cp=" FMT_CONN "\n",
 167                           __func__, ct, ct->status,
 168                           ARG_TUPLE(orig), ARG_TUPLE(&new_reply),
 169                           ARG_CONN(cp));
 170                 new_reply.dst.u3 = cp->vaddr;
 171                 new_reply.dst.u.tcp.port = cp->vport;
 172                 IP_VS_DBG(7, "%s: ct=%p, new tuples=" FMT_TUPLE ", " FMT_TUPLE
 173                           ", inout cp=" FMT_CONN "\n",
 174                           __func__, ct,
 175                           ARG_TUPLE(orig), ARG_TUPLE(&new_reply),
 176                           ARG_CONN(cp));
 177                 goto alter;
 178         }
 179
 180         /* CLIENT->VS */
 181         cp = ip_vs_conn_in_get(&p);
 182         if (cp) {
 183                 /* Change reply VS->CLIENT to RS->CLIENT */
 184                 new_reply = ct->tuplehash[IP_CT_DIR_REPLY].tuple;
 185                 IP_VS_DBG(7, "%s: ct=%p, status=0x%lX, tuples=" FMT_TUPLE ", "
 186                           FMT_TUPLE ", found outin cp=" FMT_CONN "\n",
 187                           __func__, ct, ct->status,
 188                           ARG_TUPLE(orig), ARG_TUPLE(&new_reply),
 189                           ARG_CONN(cp));
 190                 new_reply.src.u3 = cp->daddr;
 191                 new_reply.src.u.tcp.port = cp->dport;
 192                 IP_VS_DBG(7, "%s: ct=%p, new tuples=" FMT_TUPLE ", "
 193                           FMT_TUPLE ", outin cp=" FMT_CONN "\n",
 194                           __func__, ct,
 195                           ARG_TUPLE(orig), ARG_TUPLE(&new_reply),
 196                           ARG_CONN(cp));
 197                 goto alter;
 198         }
 199
 200         IP_VS_DBG(7, "%s: ct=%p, status=0x%lX, tuple=" FMT_TUPLE
 201                   " - unknown expect\n",
 202                   __func__, ct, ct->status, ARG_TUPLE(orig));
 203         return;
 204
 205 alter:
 206         /* Never alter conntrack for non-NAT conns */
 207         if (IP_VS_FWD_METHOD(cp) == IP_VS_CONN_F_MASQ)
 208                 nf_conntrack_alter_reply(ct, &new_reply);
 209         ip_vs_conn_put(cp);
 210         return;
 211 }
 212
 213 /*
 214  * Create NF conntrack expectation with wildcard (optional) source port.
 215  * Then the default callback function will alter the reply and will confirm
 216  * the conntrack entry when the first packet comes.
 217  * Use port 0 to expect connection from any port.
 218  */
 219 void ip_vs_nfct_expect_related(struct sk_buff *skb, struct nf_conn *ct,
 220                                struct ip_vs_conn *cp, u_int8_t proto,
 221                                const __be16 port, int from_rs)
 222 {
 223         struct nf_conntrack_expect *exp;
 224
 225         if (ct == NULL || nf_ct_is_untracked(ct))
 226                 return;
 227
 228         exp = nf_ct_expect_alloc(ct);
 229         if (!exp)
 230                 return;
 231
 232         nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, nf_ct_l3num(ct),
 233                         from_rs ? &cp->daddr : &cp->caddr,
 234                         from_rs ? &cp->caddr : &cp->vaddr,
 235                         proto, port ? &port : NULL,
 236                         from_rs ? &cp->cport : &cp->vport);
 237
 238         exp->expectfn = ip_vs_nfct_expect_callback;
 239
 240         IP_VS_DBG(7, "%s: ct=%p, expect tuple=" FMT_TUPLE "\n",
 241                 __func__, ct, ARG_TUPLE(&exp->tuple));
 242         nf_ct_expect_related(exp);
 243         nf_ct_expect_put(exp);
 244 }
 245 EXPORT_SYMBOL(ip_vs_nfct_expect_related);
 246
 247 /*
 248  * Our connection was terminated, try to drop the conntrack immediately
 249  */
 250 void ip_vs_conn_drop_conntrack(struct ip_vs_conn *cp)
 251 {
 252         struct nf_conntrack_tuple_hash *h;
 253         struct nf_conn *ct;
 254         struct nf_conntrack_tuple tuple;
 255
 256         if (!cp->cport)
 257                 return;
 258
 259         tuple = (struct nf_conntrack_tuple) {
 260                 .dst = { .protonum = cp->protocol, .dir = IP_CT_DIR_ORIGINAL } };
 261         tuple.src.u3 = cp->caddr;
 262         tuple.src.u.all = cp->cport;
 263         tuple.src.l3num = cp->af;
 264         tuple.dst.u3 = cp->vaddr;
 265         tuple.dst.u.all = cp->vport;
 266
 267         IP_VS_DBG(7, "%s: dropping conntrack with tuple=" FMT_TUPLE
 268                 " for conn " FMT_CONN "\n",
 269                 __func__, ARG_TUPLE(&tuple), ARG_CONN(cp));
 270
 271         h = nf_conntrack_find_get(ip_vs_conn_net(cp), NF_CT_DEFAULT_ZONE,
 272                                   &tuple);
 273         if (h) {
 274                 ct = nf_ct_tuplehash_to_ctrack(h);
 275                 /* Show what happens instead of calling nf_ct_kill() */
 276                 if (del_timer(&ct->timeout)) {
 277                         IP_VS_DBG(7, "%s: ct=%p, deleted conntrack timer for tuple="
 278                                 FMT_TUPLE "\n",
 279                                 __func__, ct, ARG_TUPLE(&tuple));
 280                         if (ct->timeout.function)
 281                                 ct->timeout.function(ct->timeout.data);
 282                 } else {
 283                         IP_VS_DBG(7, "%s: ct=%p, no conntrack timer for tuple="
 284                                 FMT_TUPLE "\n",
 285                                 __func__, ct, ARG_TUPLE(&tuple));
 286                 }
 287                 nf_ct_put(ct);
 288         } else {
 289                 IP_VS_DBG(7, "%s: no conntrack for tuple=" FMT_TUPLE "\n",
 290                         __func__, ARG_TUPLE(&tuple));
 291         }
 292 }
 293