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_seqadj.h>
  67 #include <net/netfilter/nf_conntrack_helper.h>
  68 #include <net/netfilter/nf_conntrack_zones.h>
  69
  70
  71 #define FMT_TUPLE       "%pI4:%u->%pI4:%u/%u"
  72 #define ARG_TUPLE(T)    &(T)->src.u3.ip, ntohs((T)->src.u.all), \
  73                         &(T)->dst.u3.ip, ntohs((T)->dst.u.all), \
  74                         (T)->dst.protonum
  75
  76 #define FMT_CONN        "%pI4:%u->%pI4:%u->%pI4:%u/%u:%u"
  77 #define ARG_CONN(C)     &((C)->caddr.ip), ntohs((C)->cport), \
  78                         &((C)->vaddr.ip), ntohs((C)->vport), \
  79                         &((C)->daddr.ip), ntohs((C)->dport), \
  80                         (C)->protocol, (C)->state
  81
  82 void
  83 ip_vs_update_conntrack(struct sk_buff *skb, struct ip_vs_conn *cp, int outin)
  84 {
  85         enum ip_conntrack_info ctinfo;
  86         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
  87         struct nf_conntrack_tuple new_tuple;
  88
  89         if (ct == NULL || nf_ct_is_confirmed(ct) || nf_ct_is_untracked(ct) ||
  90             nf_ct_is_dying(ct))
  91                 return;
  92
  93         /* Never alter conntrack for non-NAT conns */
  94         if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ)
  95                 return;
  96
  97         /* Alter reply only in original direction */
  98         if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL)
  99                 return;
 100
 101         /* Applications may adjust TCP seqs */
 102         if (cp->app && nf_ct_protonum(ct) == IPPROTO_TCP &&
 103             !nfct_seqadj(ct) && !nfct_seqadj_ext_add(ct))
 104                 return;
 105
 106         /*
 107          * The connection is not yet in the hashtable, so we update it.
 108          * CIP->VIP will remain the same, so leave the tuple in
 109          * IP_CT_DIR_ORIGINAL untouched.  When the reply comes back from the
 110          * real-server we will see RIP->DIP.
 111          */
 112         new_tuple = ct->tuplehash[IP_CT_DIR_REPLY].tuple;
 113         /*
 114          * This will also take care of UDP and other protocols.
 115          */
 116         if (outin) {
 117                 new_tuple.src.u3 = cp->daddr;
 118                 if (new_tuple.dst.protonum != IPPROTO_ICMP &&
 119                     new_tuple.dst.protonum != IPPROTO_ICMPV6)
 120                         new_tuple.src.u.tcp.port = cp->dport;
 121         } else {
 122                 new_tuple.dst.u3 = cp->vaddr;
 123                 if (new_tuple.dst.protonum != IPPROTO_ICMP &&
 124                     new_tuple.dst.protonum != IPPROTO_ICMPV6)
 125                         new_tuple.dst.u.tcp.port = cp->vport;
 126         }
 127         IP_VS_DBG(7, "%s: Updating conntrack ct=%p, status=0x%lX, "
 128                   "ctinfo=%d, old reply=" FMT_TUPLE
 129                   ", new reply=" FMT_TUPLE ", cp=" FMT_CONN "\n",
 130                   __func__, ct, ct->status, ctinfo,
 131                   ARG_TUPLE(&ct->tuplehash[IP_CT_DIR_REPLY].tuple),
 132                   ARG_TUPLE(&new_tuple), ARG_CONN(cp));
 133         nf_conntrack_alter_reply(ct, &new_tuple);
 134 }
 135
 136 int ip_vs_confirm_conntrack(struct sk_buff *skb)
 137 {
 138         return nf_conntrack_confirm(skb);
 139 }
 140
 141 /*
 142  * Called from init_conntrack() as expectfn handler.
 143  */
 144 static void ip_vs_nfct_expect_callback(struct nf_conn *ct,
 145         struct nf_conntrack_expect *exp)
 146 {
 147         struct nf_conntrack_tuple *orig, new_reply;
 148         struct ip_vs_conn *cp;
 149         struct ip_vs_conn_param p;
 150         struct net *net = nf_ct_net(ct);
 151
 152         if (exp->tuple.src.l3num != PF_INET)
 153                 return;
 154
 155         /*
 156          * We assume that no NF locks are held before this callback.
 157          * ip_vs_conn_out_get and ip_vs_conn_in_get should match their
 158          * expectations even if they use wildcard values, now we provide the
 159          * actual values from the newly created original conntrack direction.
 160          * The conntrack is confirmed when packet reaches IPVS hooks.
 161          */
 162
 163         /* RS->CLIENT */
 164         orig = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
 165         ip_vs_conn_fill_param(net, exp->tuple.src.l3num, orig->dst.protonum,
 166                               &orig->src.u3, orig->src.u.tcp.port,
 167                               &orig->dst.u3, orig->dst.u.tcp.port, &p);
 168         cp = ip_vs_conn_out_get(&p);
 169         if (cp) {
 170                 /* Change reply CLIENT->RS to CLIENT->VS */
 171                 new_reply = ct->tuplehash[IP_CT_DIR_REPLY].tuple;
 172                 IP_VS_DBG(7, "%s: ct=%p, status=0x%lX, tuples=" FMT_TUPLE ", "
 173                           FMT_TUPLE ", found inout cp=" FMT_CONN "\n",
 174                           __func__, ct, ct->status,
 175                           ARG_TUPLE(orig), ARG_TUPLE(&new_reply),
 176                           ARG_CONN(cp));
 177                 new_reply.dst.u3 = cp->vaddr;
 178                 new_reply.dst.u.tcp.port = cp->vport;
 179                 IP_VS_DBG(7, "%s: ct=%p, new tuples=" FMT_TUPLE ", " FMT_TUPLE
 180                           ", inout cp=" FMT_CONN "\n",
 181                           __func__, ct,
 182                           ARG_TUPLE(orig), ARG_TUPLE(&new_reply),
 183                           ARG_CONN(cp));
 184                 goto alter;
 185         }
 186
 187         /* CLIENT->VS */
 188         cp = ip_vs_conn_in_get(&p);
 189         if (cp) {
 190                 /* Change reply VS->CLIENT to RS->CLIENT */
 191                 new_reply = ct->tuplehash[IP_CT_DIR_REPLY].tuple;
 192                 IP_VS_DBG(7, "%s: ct=%p, status=0x%lX, tuples=" FMT_TUPLE ", "
 193                           FMT_TUPLE ", found outin cp=" FMT_CONN "\n",
 194                           __func__, ct, ct->status,
 195                           ARG_TUPLE(orig), ARG_TUPLE(&new_reply),
 196                           ARG_CONN(cp));
 197                 new_reply.src.u3 = cp->daddr;
 198                 new_reply.src.u.tcp.port = cp->dport;
 199                 IP_VS_DBG(7, "%s: ct=%p, new tuples=" FMT_TUPLE ", "
 200                           FMT_TUPLE ", outin cp=" FMT_CONN "\n",
 201                           __func__, ct,
 202                           ARG_TUPLE(orig), ARG_TUPLE(&new_reply),
 203                           ARG_CONN(cp));
 204                 goto alter;
 205         }
 206
 207         IP_VS_DBG(7, "%s: ct=%p, status=0x%lX, tuple=" FMT_TUPLE
 208                   " - unknown expect\n",
 209                   __func__, ct, ct->status, ARG_TUPLE(orig));
 210         return;
 211
 212 alter:
 213         /* Never alter conntrack for non-NAT conns */
 214         if (IP_VS_FWD_METHOD(cp) == IP_VS_CONN_F_MASQ)
 215                 nf_conntrack_alter_reply(ct, &new_reply);
 216         ip_vs_conn_put(cp);
 217         return;
 218 }
 219
 220 /*
 221  * Create NF conntrack expectation with wildcard (optional) source port.
 222  * Then the default callback function will alter the reply and will confirm
 223  * the conntrack entry when the first packet comes.
 224  * Use port 0 to expect connection from any port.
 225  */
 226 void ip_vs_nfct_expect_related(struct sk_buff *skb, struct nf_conn *ct,
 227                                struct ip_vs_conn *cp, u_int8_t proto,
 228                                const __be16 port, int from_rs)
 229 {
 230         struct nf_conntrack_expect *exp;
 231
 232         if (ct == NULL || nf_ct_is_untracked(ct))
 233                 return;
 234
 235         exp = nf_ct_expect_alloc(ct);
 236         if (!exp)
 237                 return;
 238
 239         nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, nf_ct_l3num(ct),
 240                         from_rs ? &cp->daddr : &cp->caddr,
 241                         from_rs ? &cp->caddr : &cp->vaddr,
 242                         proto, port ? &port : NULL,
 243                         from_rs ? &cp->cport : &cp->vport);
 244
 245         exp->expectfn = ip_vs_nfct_expect_callback;
 246
 247         IP_VS_DBG(7, "%s: ct=%p, expect tuple=" FMT_TUPLE "\n",
 248                 __func__, ct, ARG_TUPLE(&exp->tuple));
 249         nf_ct_expect_related(exp);
 250         nf_ct_expect_put(exp);
 251 }
 252 EXPORT_SYMBOL(ip_vs_nfct_expect_related);
 253
 254 /*
 255  * Our connection was terminated, try to drop the conntrack immediately
 256  */
 257 void ip_vs_conn_drop_conntrack(struct ip_vs_conn *cp)
 258 {
 259         struct nf_conntrack_tuple_hash *h;
 260         struct nf_conn *ct;
 261         struct nf_conntrack_tuple tuple;
 262
 263         if (!cp->cport)
 264                 return;
 265
 266         tuple = (struct nf_conntrack_tuple) {
 267                 .dst = { .protonum = cp->protocol, .dir = IP_CT_DIR_ORIGINAL } };
 268         tuple.src.u3 = cp->caddr;
 269         tuple.src.u.all = cp->cport;
 270         tuple.src.l3num = cp->af;
 271         tuple.dst.u3 = cp->vaddr;
 272         tuple.dst.u.all = cp->vport;
 273
 274         IP_VS_DBG(7, "%s: dropping conntrack with tuple=" FMT_TUPLE
 275                 " for conn " FMT_CONN "\n",
 276                 __func__, ARG_TUPLE(&tuple), ARG_CONN(cp));
 277
 278         h = nf_conntrack_find_get(ip_vs_conn_net(cp), NF_CT_DEFAULT_ZONE,
 279                                   &tuple);
 280         if (h) {
 281                 ct = nf_ct_tuplehash_to_ctrack(h);
 282                 /* Show what happens instead of calling nf_ct_kill() */
 283                 if (del_timer(&ct->timeout)) {
 284                         IP_VS_DBG(7, "%s: ct=%p, deleted conntrack timer for tuple="
 285                                 FMT_TUPLE "\n",
 286                                 __func__, ct, ARG_TUPLE(&tuple));
 287                         if (ct->timeout.function)
 288                                 ct->timeout.function(ct->timeout.data);
 289                 } else {
 290                         IP_VS_DBG(7, "%s: ct=%p, no conntrack timer for tuple="
 291                                 FMT_TUPLE "\n",
 292                                 __func__, ct, ARG_TUPLE(&tuple));
 293                 }
 294                 nf_ct_put(ct);
 295         } else {
 296                 IP_VS_DBG(7, "%s: no conntrack for tuple=" FMT_TUPLE "\n",
 297                         __func__, ARG_TUPLE(&tuple));
 298         }
 299 }
 300