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