xref: /openbmc/linux/net/netfilter/ipvs/ip_vs_nfct.c (revision 3c00fb0b)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * ip_vs_nfct.c:	Netfilter connection tracking support for IPVS
4  *
5  * Portions Copyright (C) 2001-2002
6  * Antefacto Ltd, 181 Parnell St, Dublin 1, Ireland.
7  *
8  * Portions Copyright (C) 2003-2010
9  * Julian Anastasov
10  *
11  * Authors:
12  * Ben North <ben@redfrontdoor.org>
13  * Julian Anastasov <ja@ssi.bg>		Reorganize and sync with latest kernels
14  * Hannes Eder <heder@google.com>	Extend NFCT support for FTP, ipvs match
15  *
16  * Current status:
17  *
18  * - provide conntrack confirmation for new and related connections, by
19  * this way we can see their proper conntrack state in all hooks
20  * - support for all forwarding methods, not only NAT
21  * - FTP support (NAT), ability to support other NAT apps with expectations
22  * - to correctly create expectations for related NAT connections the proper
23  * NF conntrack support must be already installed, eg. ip_vs_ftp requires
24  * nf_conntrack_ftp ... iptables_nat for the same ports (but no iptables
25  * NAT rules are needed)
26  * - alter reply for NAT when forwarding packet in original direction:
27  * conntrack from client in NEW or RELATED (Passive FTP DATA) state or
28  * when RELATED conntrack is created from real server (Active FTP DATA)
29  * - if iptables_nat is not loaded the Passive FTP will not work (the
30  * PASV response can not be NAT-ed) but Active FTP should work
31  */
32 
33 #define KMSG_COMPONENT "IPVS"
34 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
35 
36 #include <linux/module.h>
37 #include <linux/types.h>
38 #include <linux/kernel.h>
39 #include <linux/errno.h>
40 #include <linux/compiler.h>
41 #include <linux/vmalloc.h>
42 #include <linux/skbuff.h>
43 #include <net/ip.h>
44 #include <linux/netfilter.h>
45 #include <linux/netfilter_ipv4.h>
46 #include <net/ip_vs.h>
47 #include <net/netfilter/nf_conntrack_core.h>
48 #include <net/netfilter/nf_conntrack_expect.h>
49 #include <net/netfilter/nf_conntrack_seqadj.h>
50 #include <net/netfilter/nf_conntrack_helper.h>
51 #include <net/netfilter/nf_conntrack_zones.h>
52 
53 
54 #define FMT_TUPLE	"%s:%u->%s:%u/%u"
55 #define ARG_TUPLE(T)	IP_VS_DBG_ADDR((T)->src.l3num, &(T)->src.u3),	\
56 			ntohs((T)->src.u.all),				\
57 			IP_VS_DBG_ADDR((T)->src.l3num, &(T)->dst.u3),	\
58 			ntohs((T)->dst.u.all),				\
59 			(T)->dst.protonum
60 
61 #define FMT_CONN	"%s:%u->%s:%u->%s:%u/%u:%u"
62 #define ARG_CONN(C)	IP_VS_DBG_ADDR((C)->af, &((C)->caddr)),		\
63 			ntohs((C)->cport),				\
64 			IP_VS_DBG_ADDR((C)->af, &((C)->vaddr)),		\
65 			ntohs((C)->vport),				\
66 			IP_VS_DBG_ADDR((C)->daf, &((C)->daddr)),	\
67 			ntohs((C)->dport),				\
68 			(C)->protocol, (C)->state
69 
70 void
ip_vs_update_conntrack(struct sk_buff * skb,struct ip_vs_conn * cp,int outin)71 ip_vs_update_conntrack(struct sk_buff *skb, struct ip_vs_conn *cp, int outin)
72 {
73 	enum ip_conntrack_info ctinfo;
74 	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
75 	struct nf_conntrack_tuple new_tuple;
76 
77 	if (ct == NULL || nf_ct_is_confirmed(ct) ||
78 	    nf_ct_is_dying(ct))
79 		return;
80 
81 	/* Never alter conntrack for non-NAT conns */
82 	if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ)
83 		return;
84 
85 	/* Never alter conntrack for OPS conns (no reply is expected) */
86 	if (cp->flags & IP_VS_CONN_F_ONE_PACKET)
87 		return;
88 
89 	/* Alter reply only in original direction */
90 	if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL)
91 		return;
92 
93 	/* Applications may adjust TCP seqs */
94 	if (cp->app && nf_ct_protonum(ct) == IPPROTO_TCP &&
95 	    !nfct_seqadj(ct) && !nfct_seqadj_ext_add(ct))
96 		return;
97 
98 	/*
99 	 * The connection is not yet in the hashtable, so we update it.
100 	 * CIP->VIP will remain the same, so leave the tuple in
101 	 * IP_CT_DIR_ORIGINAL untouched.  When the reply comes back from the
102 	 * real-server we will see RIP->DIP.
103 	 */
104 	new_tuple = ct->tuplehash[IP_CT_DIR_REPLY].tuple;
105 	/*
106 	 * This will also take care of UDP and other protocols.
107 	 */
108 	if (outin) {
109 		new_tuple.src.u3 = cp->daddr;
110 		if (new_tuple.dst.protonum != IPPROTO_ICMP &&
111 		    new_tuple.dst.protonum != IPPROTO_ICMPV6)
112 			new_tuple.src.u.tcp.port = cp->dport;
113 	} else {
114 		new_tuple.dst.u3 = cp->vaddr;
115 		if (new_tuple.dst.protonum != IPPROTO_ICMP &&
116 		    new_tuple.dst.protonum != IPPROTO_ICMPV6)
117 			new_tuple.dst.u.tcp.port = cp->vport;
118 	}
119 	IP_VS_DBG_BUF(7, "%s: Updating conntrack ct=%p, status=0x%lX, "
120 		      "ctinfo=%d, old reply=" FMT_TUPLE "\n",
121 		      __func__, ct, ct->status, ctinfo,
122 		      ARG_TUPLE(&ct->tuplehash[IP_CT_DIR_REPLY].tuple));
123 	IP_VS_DBG_BUF(7, "%s: Updating conntrack ct=%p, status=0x%lX, "
124 		      "ctinfo=%d, new reply=" FMT_TUPLE "\n",
125 		      __func__, ct, ct->status, ctinfo,
126 		      ARG_TUPLE(&new_tuple));
127 	nf_conntrack_alter_reply(ct, &new_tuple);
128 	IP_VS_DBG_BUF(7, "%s: Updated conntrack ct=%p for cp=" FMT_CONN "\n",
129 		      __func__, ct, ARG_CONN(cp));
130 }
131 
ip_vs_confirm_conntrack(struct sk_buff * skb)132 int ip_vs_confirm_conntrack(struct sk_buff *skb)
133 {
134 	return nf_conntrack_confirm(skb);
135 }
136 
137 /*
138  * Called from init_conntrack() as expectfn handler.
139  */
ip_vs_nfct_expect_callback(struct nf_conn * ct,struct nf_conntrack_expect * exp)140 static void ip_vs_nfct_expect_callback(struct nf_conn *ct,
141 	struct nf_conntrack_expect *exp)
142 {
143 	struct nf_conntrack_tuple *orig, new_reply;
144 	struct ip_vs_conn *cp;
145 	struct ip_vs_conn_param p;
146 	struct net *net = nf_ct_net(ct);
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_ipvs(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 		IP_VS_DBG_BUF(7, "%s: for ct=%p, status=0x%lX found inout cp="
165 			      FMT_CONN "\n",
166 			      __func__, ct, ct->status, ARG_CONN(cp));
167 		new_reply = ct->tuplehash[IP_CT_DIR_REPLY].tuple;
168 		IP_VS_DBG_BUF(7, "%s: ct=%p before alter: reply tuple="
169 			      FMT_TUPLE "\n",
170 			      __func__, ct, ARG_TUPLE(&new_reply));
171 		new_reply.dst.u3 = cp->vaddr;
172 		new_reply.dst.u.tcp.port = cp->vport;
173 		goto alter;
174 	}
175 
176 	/* CLIENT->VS */
177 	cp = ip_vs_conn_in_get(&p);
178 	if (cp) {
179 		/* Change reply VS->CLIENT to RS->CLIENT */
180 		IP_VS_DBG_BUF(7, "%s: for ct=%p, status=0x%lX found outin 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.src.u3 = cp->daddr;
188 		new_reply.src.u.tcp.port = cp->dport;
189 		goto alter;
190 	}
191 
192 	IP_VS_DBG_BUF(7, "%s: ct=%p, status=0x%lX, tuple=" FMT_TUPLE
193 		      " - unknown expect\n",
194 		      __func__, ct, ct->status, ARG_TUPLE(orig));
195 	return;
196 
197 alter:
198 	/* Never alter conntrack for non-NAT conns */
199 	if (IP_VS_FWD_METHOD(cp) == IP_VS_CONN_F_MASQ)
200 		nf_conntrack_alter_reply(ct, &new_reply);
201 	ip_vs_conn_put(cp);
202 	return;
203 }
204 
205 /*
206  * Create NF conntrack expectation with wildcard (optional) source port.
207  * Then the default callback function will alter the reply and will confirm
208  * the conntrack entry when the first packet comes.
209  * Use port 0 to expect connection from any port.
210  */
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)211 void ip_vs_nfct_expect_related(struct sk_buff *skb, struct nf_conn *ct,
212 			       struct ip_vs_conn *cp, u_int8_t proto,
213 			       const __be16 port, int from_rs)
214 {
215 	struct nf_conntrack_expect *exp;
216 
217 	if (ct == NULL)
218 		return;
219 
220 	exp = nf_ct_expect_alloc(ct);
221 	if (!exp)
222 		return;
223 
224 	nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, nf_ct_l3num(ct),
225 			from_rs ? &cp->daddr : &cp->caddr,
226 			from_rs ? &cp->caddr : &cp->vaddr,
227 			proto, port ? &port : NULL,
228 			from_rs ? &cp->cport : &cp->vport);
229 
230 	exp->expectfn = ip_vs_nfct_expect_callback;
231 
232 	IP_VS_DBG_BUF(7, "%s: ct=%p, expect tuple=" FMT_TUPLE "\n",
233 		      __func__, ct, ARG_TUPLE(&exp->tuple));
234 	nf_ct_expect_related(exp, 0);
235 	nf_ct_expect_put(exp);
236 }
237 EXPORT_SYMBOL(ip_vs_nfct_expect_related);
238 
239 /*
240  * Our connection was terminated, try to drop the conntrack immediately
241  */
ip_vs_conn_drop_conntrack(struct ip_vs_conn * cp)242 void ip_vs_conn_drop_conntrack(struct ip_vs_conn *cp)
243 {
244 	struct nf_conntrack_tuple_hash *h;
245 	struct nf_conn *ct;
246 	struct nf_conntrack_tuple tuple;
247 
248 	if (!cp->cport)
249 		return;
250 
251 	tuple = (struct nf_conntrack_tuple) {
252 		.dst = { .protonum = cp->protocol, .dir = IP_CT_DIR_ORIGINAL } };
253 	tuple.src.u3 = cp->caddr;
254 	tuple.src.u.all = cp->cport;
255 	tuple.src.l3num = cp->af;
256 	tuple.dst.u3 = cp->vaddr;
257 	tuple.dst.u.all = cp->vport;
258 
259 	IP_VS_DBG_BUF(7, "%s: dropping conntrack for conn " FMT_CONN "\n",
260 		      __func__, ARG_CONN(cp));
261 
262 	h = nf_conntrack_find_get(cp->ipvs->net, &nf_ct_zone_dflt, &tuple);
263 	if (h) {
264 		ct = nf_ct_tuplehash_to_ctrack(h);
265 		if (nf_ct_kill(ct)) {
266 			IP_VS_DBG_BUF(7, "%s: ct=%p deleted for tuple="
267 				      FMT_TUPLE "\n",
268 				      __func__, ct, ARG_TUPLE(&tuple));
269 		} else {
270 			IP_VS_DBG_BUF(7, "%s: ct=%p, no conntrack for tuple="
271 				      FMT_TUPLE "\n",
272 				      __func__, ct, ARG_TUPLE(&tuple));
273 		}
274 		nf_ct_put(ct);
275 	} else {
276 		IP_VS_DBG_BUF(7, "%s: no conntrack for tuple=" FMT_TUPLE "\n",
277 			      __func__, ARG_TUPLE(&tuple));
278 	}
279 }
280 
281