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, write to the Free Software
  23  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  24  *
  25  *
  26  * Authors:
  27  * Ben North <ben@redfrontdoor.org>
  28  * Julian Anastasov <ja@ssi.bg>         Reorganize and sync with latest kernels
  29  * Hannes Eder <heder@google.com>       Extend NFCT support for FTP, ipvs match
  30  *
  31  *
  32  * Current status:
  33  *
  34  * - provide conntrack confirmation for new and related connections, by
  35  * this way we can see their proper conntrack state in all hooks
  36  * - support for all forwarding methods, not only NAT
  37  * - FTP support (NAT), ability to support other NAT apps with expectations
  38  * - to correctly create expectations for related NAT connections the proper
  39  * NF conntrack support must be already installed, eg. ip_vs_ftp requires
  40  * nf_conntrack_ftp ... iptables_nat for the same ports (but no iptables
  41  * NAT rules are needed)
  42  * - alter reply for NAT when forwarding packet in original direction:
  43  * conntrack from client in NEW or RELATED (Passive FTP DATA) state or
  44  * when RELATED conntrack is created from real server (Active FTP DATA)
  45  * - if iptables_nat is not loaded the Passive FTP will not work (the
  46  * PASV response can not be NAT-ed) but Active FTP should work
  47  *
  48  */
  49
  50 #define KMSG_COMPONENT "IPVS"
  51 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  52
  53 #include <linux/module.h>
  54 #include <linux/types.h>
  55 #include <linux/kernel.h>
  56 #include <linux/errno.h>
  57 #include <linux/compiler.h>
  58 #include <linux/vmalloc.h>
  59 #include <linux/skbuff.h>
  60 #include <net/ip.h>
  61 #include <linux/netfilter.h>
  62 #include <linux/netfilter_ipv4.h>
  63 #include <net/ip_vs.h>
  64 #include <net/netfilter/nf_conntrack_core.h>
  65 #include <net/netfilter/nf_conntrack_expect.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 = 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         /* Alter reply only in original direction */
  97         if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL)
  98                 return;
  99
 100         /*
 101          * The connection is not yet in the hashtable, so we update it.
 102          * CIP->VIP will remain the same, so leave the tuple in
 103          * IP_CT_DIR_ORIGINAL untouched.  When the reply comes back from the
 104          * real-server we will see RIP->DIP.
 105          */
 106         new_tuple = ct->tuplehash[IP_CT_DIR_REPLY].tuple;
 107         /*
 108          * This will also take care of UDP and other protocols.
 109          */
 110         if (outin) {
 111                 new_tuple.src.u3 = cp->daddr;
 112                 if (new_tuple.dst.protonum != IPPROTO_ICMP &&
 113                     new_tuple.dst.protonum != IPPROTO_ICMPV6)
 114                         new_tuple.src.u.tcp.port = cp->dport;
 115         } else {
 116                 new_tuple.dst.u3 = cp->vaddr;
 117                 if (new_tuple.dst.protonum != IPPROTO_ICMP &&
 118                     new_tuple.dst.protonum != IPPROTO_ICMPV6)
 119                         new_tuple.dst.u.tcp.port = cp->vport;
 120         }
 121         IP_VS_DBG(7, "%s: Updating conntrack ct=%p, status=0x%lX, "
 122                   "ctinfo=%d, old reply=" FMT_TUPLE
 123                   ", new reply=" FMT_TUPLE ", cp=" FMT_CONN "\n",
 124                   __func__, ct, ct->status, ctinfo,
 125                   ARG_TUPLE(&ct->tuplehash[IP_CT_DIR_REPLY].tuple),
 126                   ARG_TUPLE(&new_tuple), ARG_CONN(cp));
 127         nf_conntrack_alter_reply(ct, &new_tuple);
 128 }
 129
 130 int ip_vs_confirm_conntrack(struct sk_buff *skb, struct ip_vs_conn *cp)
 131 {
 132         return nf_conntrack_confirm(skb);
 133 }
 134
 135 /*
 136  * Called from init_conntrack() as expectfn handler.
 137  */
 138 static void ip_vs_nfct_expect_callback(struct nf_conn *ct,
 139         struct nf_conntrack_expect *exp)
 140 {
 141         struct nf_conntrack_tuple *orig, new_reply;
 142         struct ip_vs_conn *cp;
 143         struct ip_vs_conn_param p;
 144         struct net *net = nf_ct_net(ct);
 145
 146         if (exp->tuple.src.l3num != PF_INET)
 147                 return;
 148
 149         /*
 150          * We assume that no NF locks are held before this callback.
 151          * ip_vs_conn_out_get and ip_vs_conn_in_get should match their
 152          * expectations even if they use wildcard values, now we provide the
 153          * actual values from the newly created original conntrack direction.
 154          * The conntrack is confirmed when packet reaches IPVS hooks.
 155          */
 156
 157         /* RS->CLIENT */
 158         orig = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
 159         ip_vs_conn_fill_param(net, exp->tuple.src.l3num, orig->dst.protonum,
 160                               &orig->src.u3, orig->src.u.tcp.port,
 161                               &orig->dst.u3, orig->dst.u.tcp.port, &p);
 162         cp = ip_vs_conn_out_get(&p);
 163         if (cp) {
 164                 /* Change reply CLIENT->RS to CLIENT->VS */
 165                 new_reply = ct->tuplehash[IP_CT_DIR_REPLY].tuple;
 166                 IP_VS_DBG(7, "%s: ct=%p, status=0x%lX, tuples=" FMT_TUPLE ", "
 167                           FMT_TUPLE ", found inout cp=" FMT_CONN "\n",
 168                           __func__, ct, ct->status,
 169                           ARG_TUPLE(orig), ARG_TUPLE(&new_reply),
 170                           ARG_CONN(cp));
 171                 new_reply.dst.u3 = cp->vaddr;
 172                 new_reply.dst.u.tcp.port = cp->vport;
 173                 IP_VS_DBG(7, "%s: ct=%p, new tuples=" FMT_TUPLE ", " FMT_TUPLE
 174                           ", inout cp=" FMT_CONN "\n",
 175                           __func__, ct,
 176                           ARG_TUPLE(orig), ARG_TUPLE(&new_reply),
 177                           ARG_CONN(cp));
 178                 goto alter;
 179         }
 180
 181         /* CLIENT->VS */
 182         cp = ip_vs_conn_in_get(&p);
 183         if (cp) {
 184                 /* Change reply VS->CLIENT to RS->CLIENT */
 185                 new_reply = ct->tuplehash[IP_CT_DIR_REPLY].tuple;
 186                 IP_VS_DBG(7, "%s: ct=%p, status=0x%lX, tuples=" FMT_TUPLE ", "
 187                           FMT_TUPLE ", found outin cp=" FMT_CONN "\n",
 188                           __func__, ct, ct->status,
 189                           ARG_TUPLE(orig), ARG_TUPLE(&new_reply),
 190                           ARG_CONN(cp));
 191                 new_reply.src.u3 = cp->daddr;
 192                 new_reply.src.u.tcp.port = cp->dport;
 193                 IP_VS_DBG(7, "%s: ct=%p, new tuples=" FMT_TUPLE ", "
 194                           FMT_TUPLE ", outin cp=" FMT_CONN "\n",
 195                           __func__, ct,
 196                           ARG_TUPLE(orig), ARG_TUPLE(&new_reply),
 197                           ARG_CONN(cp));
 198                 goto alter;
 199         }
 200
 201         IP_VS_DBG(7, "%s: ct=%p, status=0x%lX, tuple=" FMT_TUPLE
 202                   " - unknown expect\n",
 203                   __func__, ct, ct->status, ARG_TUPLE(orig));
 204         return;
 205
 206 alter:
 207         /* Never alter conntrack for non-NAT conns */
 208         if (IP_VS_FWD_METHOD(cp) == IP_VS_CONN_F_MASQ)
 209                 nf_conntrack_alter_reply(ct, &new_reply);
 210         ip_vs_conn_put(cp);
 211         return;
 212 }
 213
 214 /*
 215  * Create NF conntrack expectation with wildcard (optional) source port.
 216  * Then the default callback function will alter the reply and will confirm
 217  * the conntrack entry when the first packet comes.
 218  * Use port 0 to expect connection from any port.
 219  */
 220 void ip_vs_nfct_expect_related(struct sk_buff *skb, struct nf_conn *ct,
 221                                struct ip_vs_conn *cp, u_int8_t proto,
 222                                const __be16 port, int from_rs)
 223 {
 224         struct nf_conntrack_expect *exp;
 225
 226         if (ct == NULL || nf_ct_is_untracked(ct))
 227                 return;
 228
 229         exp = nf_ct_expect_alloc(ct);
 230         if (!exp)
 231                 return;
 232
 233         nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, nf_ct_l3num(ct),
 234                         from_rs ? &cp->daddr : &cp->caddr,
 235                         from_rs ? &cp->caddr : &cp->vaddr,
 236                         proto, port ? &port : NULL,
 237                         from_rs ? &cp->cport : &cp->vport);
 238
 239         exp->expectfn = ip_vs_nfct_expect_callback;
 240
 241         IP_VS_DBG(7, "%s: ct=%p, expect tuple=" FMT_TUPLE "\n",
 242                 __func__, ct, ARG_TUPLE(&exp->tuple));
 243         nf_ct_expect_related(exp);
 244         nf_ct_expect_put(exp);
 245 }
 246 EXPORT_SYMBOL(ip_vs_nfct_expect_related);
 247
 248 /*
 249  * Our connection was terminated, try to drop the conntrack immediately
 250  */
 251 void ip_vs_conn_drop_conntrack(struct ip_vs_conn *cp)
 252 {
 253         struct nf_conntrack_tuple_hash *h;
 254         struct nf_conn *ct;
 255         struct nf_conntrack_tuple tuple;
 256
 257         if (!cp->cport)
 258                 return;
 259
 260         tuple = (struct nf_conntrack_tuple) {
 261                 .dst = { .protonum = cp->protocol, .dir = IP_CT_DIR_ORIGINAL } };
 262         tuple.src.u3 = cp->caddr;
 263         tuple.src.u.all = cp->cport;
 264         tuple.src.l3num = cp->af;
 265         tuple.dst.u3 = cp->vaddr;
 266         tuple.dst.u.all = cp->vport;
 267
 268         IP_VS_DBG(7, "%s: dropping conntrack with tuple=" FMT_TUPLE
 269                 " for conn " FMT_CONN "\n",
 270                 __func__, ARG_TUPLE(&tuple), ARG_CONN(cp));
 271
 272         h = nf_conntrack_find_get(ip_vs_conn_net(cp), NF_CT_DEFAULT_ZONE,
 273                                   &tuple);
 274         if (h) {
 275                 ct = nf_ct_tuplehash_to_ctrack(h);
 276                 /* Show what happens instead of calling nf_ct_kill() */
 277                 if (del_timer(&ct->timeout)) {
 278                         IP_VS_DBG(7, "%s: ct=%p, deleted conntrack timer for tuple="
 279                                 FMT_TUPLE "\n",
 280                                 __func__, ct, ARG_TUPLE(&tuple));
 281                         if (ct->timeout.function)
 282                                 ct->timeout.function(ct->timeout.data);
 283                 } else {
 284                         IP_VS_DBG(7, "%s: ct=%p, no conntrack timer for tuple="
 285                                 FMT_TUPLE "\n",
 286                                 __func__, ct, ARG_TUPLE(&tuple));
 287                 }
 288                 nf_ct_put(ct);
 289         } else {
 290                 IP_VS_DBG(7, "%s: no conntrack for tuple=" FMT_TUPLE "\n",
 291                         __func__, ARG_TUPLE(&tuple));
 292         }
 293 }
 294