[mirror_ubuntu-bionic-kernel.git] / net / ipv4 / netfilter / nf_nat_sip.c

/* SIP extension for UDP NAT alteration.
 *
 * (C) 2005 by Christian Hentschel <chentschel@arnet.com.ar>
 * based on RR's ip_nat_ftp.c and other modules.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/ip.h>
#include <linux/udp.h>

#include <net/netfilter/nf_nat.h>
#include <net/netfilter/nf_nat_helper.h>
#include <net/netfilter/nf_nat_rule.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_expect.h>
#include <linux/netfilter/nf_conntrack_sip.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Christian Hentschel <chentschel@arnet.com.ar>");
MODULE_DESCRIPTION("SIP NAT helper");
MODULE_ALIAS("ip_nat_sip");

#if 0
#define DEBUGP printk
#else
#define DEBUGP(format, args...)
#endif

struct addr_map {
	struct {
		char		src[sizeof("nnn.nnn.nnn.nnn:nnnnn")];
		char		dst[sizeof("nnn.nnn.nnn.nnn:nnnnn")];
		unsigned int	srclen, srciplen;
		unsigned int	dstlen, dstiplen;
	} addr[IP_CT_DIR_MAX];
};

static void addr_map_init(struct nf_conn *ct, struct addr_map *map)
{
	struct nf_conntrack_tuple *t;
	enum ip_conntrack_dir dir;
	unsigned int n;

	for (dir = 0; dir < IP_CT_DIR_MAX; dir++) {
		t = &ct->tuplehash[dir].tuple;

		n = sprintf(map->addr[dir].src, "%u.%u.%u.%u",
			    NIPQUAD(t->src.u3.ip));
		map->addr[dir].srciplen = n;
		n += sprintf(map->addr[dir].src + n, ":%u",
			     ntohs(t->src.u.udp.port));
		map->addr[dir].srclen = n;

		n = sprintf(map->addr[dir].dst, "%u.%u.%u.%u",
			    NIPQUAD(t->dst.u3.ip));
		map->addr[dir].dstiplen = n;
		n += sprintf(map->addr[dir].dst + n, ":%u",
			     ntohs(t->dst.u.udp.port));
		map->addr[dir].dstlen = n;
	}
}

static int map_sip_addr(struct sk_buff **pskb, enum ip_conntrack_info ctinfo,
			struct nf_conn *ct, const char **dptr, size_t dlen,
			enum sip_header_pos pos, struct addr_map *map)
{
	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
	unsigned int matchlen, matchoff, addrlen;
	char *addr;

	if (ct_sip_get_info(ct, *dptr, dlen, &matchoff, &matchlen, pos) <= 0)
		return 1;

	if ((matchlen == map->addr[dir].srciplen ||
	     matchlen == map->addr[dir].srclen) &&
	    memcmp(*dptr + matchoff, map->addr[dir].src, matchlen) == 0) {
		addr    = map->addr[!dir].dst;
		addrlen = map->addr[!dir].dstlen;
	} else if ((matchlen == map->addr[dir].dstiplen ||
		    matchlen == map->addr[dir].dstlen) &&
		   memcmp(*dptr + matchoff, map->addr[dir].dst, matchlen) == 0) {
		addr    = map->addr[!dir].src;
		addrlen = map->addr[!dir].srclen;
	} else
		return 1;

	if (!nf_nat_mangle_udp_packet(pskb, ct, ctinfo,
	                              matchoff, matchlen, addr, addrlen))
		return 0;
	*dptr = (*pskb)->data + (*pskb)->nh.iph->ihl*4 + sizeof(struct udphdr);
	return 1;

}

static unsigned int ip_nat_sip(struct sk_buff **pskb,
			       enum ip_conntrack_info ctinfo,
			       struct nf_conn *ct,
			       const char **dptr)
{
	enum sip_header_pos pos;
	struct addr_map map;
	int dataoff, datalen;

	dataoff = (*pskb)->nh.iph->ihl*4 + sizeof(struct udphdr);
	datalen = (*pskb)->len - dataoff;
	if (datalen < sizeof("SIP/2.0") - 1)
		return NF_DROP;

	addr_map_init(ct, &map);

	/* Basic rules: requests and responses. */
	if (strncmp(*dptr, "SIP/2.0", sizeof("SIP/2.0") - 1) != 0) {
		/* 10.2: Constructing the REGISTER Request:
		 *
		 * The "userinfo" and "@" components of the SIP URI MUST NOT
		 * be present.
		 */
		if (datalen >= sizeof("REGISTER") - 1 &&
		    strncmp(*dptr, "REGISTER", sizeof("REGISTER") - 1) == 0)
			pos = POS_REG_REQ_URI;
		else
			pos = POS_REQ_URI;

		if (!map_sip_addr(pskb, ctinfo, ct, dptr, datalen, pos, &map))
			return NF_DROP;
	}

	if (!map_sip_addr(pskb, ctinfo, ct, dptr, datalen, POS_FROM, &map) ||
	    !map_sip_addr(pskb, ctinfo, ct, dptr, datalen, POS_TO, &map) ||
	    !map_sip_addr(pskb, ctinfo, ct, dptr, datalen, POS_VIA, &map) ||
	    !map_sip_addr(pskb, ctinfo, ct, dptr, datalen, POS_CONTACT, &map))
		return NF_DROP;
	return NF_ACCEPT;
}

static unsigned int mangle_sip_packet(struct sk_buff **pskb,
				      enum ip_conntrack_info ctinfo,
				      struct nf_conn *ct,
				      const char **dptr, size_t dlen,
				      char *buffer, int bufflen,
				      enum sip_header_pos pos)
{
	unsigned int matchlen, matchoff;

	if (ct_sip_get_info(ct, *dptr, dlen, &matchoff, &matchlen, pos) <= 0)
		return 0;

	if (!nf_nat_mangle_udp_packet(pskb, ct, ctinfo,
	                              matchoff, matchlen, buffer, bufflen))
		return 0;

	/* We need to reload this. Thanks Patrick. */
	*dptr = (*pskb)->data + (*pskb)->nh.iph->ihl*4 + sizeof(struct udphdr);
	return 1;
}

static int mangle_content_len(struct sk_buff **pskb,
			      enum ip_conntrack_info ctinfo,
			      struct nf_conn *ct,
			      const char *dptr)
{
	unsigned int dataoff, matchoff, matchlen;
	char buffer[sizeof("65536")];
	int bufflen;

	dataoff = (*pskb)->nh.iph->ihl*4 + sizeof(struct udphdr);

	/* Get actual SDP lenght */
	if (ct_sip_get_info(ct, dptr, (*pskb)->len - dataoff, &matchoff,
	                    &matchlen, POS_SDP_HEADER) > 0) {

		/* since ct_sip_get_info() give us a pointer passing 'v='
		   we need to add 2 bytes in this count. */
		int c_len = (*pskb)->len - dataoff - matchoff + 2;

		/* Now, update SDP length */
		if (ct_sip_get_info(ct, dptr, (*pskb)->len - dataoff, &matchoff,
		                    &matchlen, POS_CONTENT) > 0) {

			bufflen = sprintf(buffer, "%u", c_len);
			return nf_nat_mangle_udp_packet(pskb, ct, ctinfo,
							matchoff, matchlen,
							buffer, bufflen);
		}
	}
	return 0;
}

static unsigned int mangle_sdp(struct sk_buff **pskb,
			       enum ip_conntrack_info ctinfo,
			       struct nf_conn *ct,
			       __be32 newip, u_int16_t port,
			       const char *dptr)
{
	char buffer[sizeof("nnn.nnn.nnn.nnn")];
	unsigned int dataoff, bufflen;

	dataoff = (*pskb)->nh.iph->ihl*4 + sizeof(struct udphdr);

	/* Mangle owner and contact info. */
	bufflen = sprintf(buffer, "%u.%u.%u.%u", NIPQUAD(newip));
	if (!mangle_sip_packet(pskb, ctinfo, ct, &dptr, (*pskb)->len - dataoff,
	                       buffer, bufflen, POS_OWNER_IP4))
		return 0;

	if (!mangle_sip_packet(pskb, ctinfo, ct, &dptr, (*pskb)->len - dataoff,
	                       buffer, bufflen, POS_CONNECTION_IP4))
		return 0;

	/* Mangle media port. */
	bufflen = sprintf(buffer, "%u", port);
	if (!mangle_sip_packet(pskb, ctinfo, ct, &dptr, (*pskb)->len - dataoff,
	                       buffer, bufflen, POS_MEDIA))
		return 0;

	return mangle_content_len(pskb, ctinfo, ct, dptr);
}

/* So, this packet has hit the connection tracking matching code.
   Mangle it, and change the expectation to match the new version. */
static unsigned int ip_nat_sdp(struct sk_buff **pskb,
			       enum ip_conntrack_info ctinfo,
			       struct nf_conntrack_expect *exp,
			       const char *dptr)
{
	struct nf_conn *ct = exp->master;
	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
	__be32 newip;
	u_int16_t port;

	DEBUGP("ip_nat_sdp():\n");

	/* Connection will come from reply */
	newip = ct->tuplehash[!dir].tuple.dst.u3.ip;

	exp->tuple.dst.u3.ip = newip;
	exp->saved_proto.udp.port = exp->tuple.dst.u.udp.port;
	exp->dir = !dir;

	/* When you see the packet, we need to NAT it the same as the
	   this one. */
	exp->expectfn = nf_nat_follow_master;

	/* Try to get same port: if not, try to change it. */
	for (port = ntohs(exp->saved_proto.udp.port); port != 0; port++) {
		exp->tuple.dst.u.udp.port = htons(port);
		if (nf_conntrack_expect_related(exp) == 0)
			break;
	}

	if (port == 0)
		return NF_DROP;

	if (!mangle_sdp(pskb, ctinfo, ct, newip, port, dptr)) {
		nf_conntrack_unexpect_related(exp);
		return NF_DROP;
	}
	return NF_ACCEPT;
}

static void __exit nf_nat_sip_fini(void)
{
	rcu_assign_pointer(nf_nat_sip_hook, NULL);
	rcu_assign_pointer(nf_nat_sdp_hook, NULL);
	synchronize_rcu();
}

static int __init nf_nat_sip_init(void)
{
	BUG_ON(rcu_dereference(nf_nat_sip_hook));
	BUG_ON(rcu_dereference(nf_nat_sdp_hook));
	rcu_assign_pointer(nf_nat_sip_hook, ip_nat_sip);
	rcu_assign_pointer(nf_nat_sdp_hook, ip_nat_sdp);
	return 0;
}

module_init(nf_nat_sip_init);
module_exit(nf_nat_sip_fini);
Commit	Line	Data
9fafcd7b PM	1	/* SIP extension for UDP NAT alteration.
	2	*
	3	* (C) 2005 by Christian Hentschel <chentschel@arnet.com.ar>
	4	* based on RR's ip_nat_ftp.c and other modules.
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License version 2 as
	8	* published by the Free Software Foundation.
	9	*/
	10
	11	#include <linux/module.h>
	12	#include <linux/skbuff.h>
	13	#include <linux/ip.h>
	14	#include <linux/udp.h>
	15
	16	#include <net/netfilter/nf_nat.h>
	17	#include <net/netfilter/nf_nat_helper.h>
	18	#include <net/netfilter/nf_nat_rule.h>
	19	#include <net/netfilter/nf_conntrack_helper.h>
	20	#include <net/netfilter/nf_conntrack_expect.h>
	21	#include <linux/netfilter/nf_conntrack_sip.h>
	22
	23	MODULE_LICENSE("GPL");
	24	MODULE_AUTHOR("Christian Hentschel <chentschel@arnet.com.ar>");
	25	MODULE_DESCRIPTION("SIP NAT helper");
	26	MODULE_ALIAS("ip_nat_sip");
	27
	28	#if 0
	29	#define DEBUGP printk
	30	#else
	31	#define DEBUGP(format, args...)
	32	#endif
	33
	34	struct addr_map {
	35	struct {
	36	char src[sizeof("nnn.nnn.nnn.nnn:nnnnn")];
	37	char dst[sizeof("nnn.nnn.nnn.nnn:nnnnn")];
	38	unsigned int srclen, srciplen;
	39	unsigned int dstlen, dstiplen;
	40	} addr[IP_CT_DIR_MAX];
	41	};
	42
	43	static void addr_map_init(struct nf_conn ct, struct addr_map map)
	44	{
	45	struct nf_conntrack_tuple *t;
	46	enum ip_conntrack_dir dir;
	47	unsigned int n;
	48
	49	for (dir = 0; dir < IP_CT_DIR_MAX; dir++) {
	50	t = &ct->tuplehash[dir].tuple;
	51
	52	n = sprintf(map->addr[dir].src, "%u.%u.%u.%u",
	53	NIPQUAD(t->src.u3.ip));
	54	map->addr[dir].srciplen = n;
	55	n += sprintf(map->addr[dir].src + n, ":%u",
	56	ntohs(t->src.u.udp.port));
	57	map->addr[dir].srclen = n;
	58
	59	n = sprintf(map->addr[dir].dst, "%u.%u.%u.%u",
	60	NIPQUAD(t->dst.u3.ip));
	61	map->addr[dir].dstiplen = n;
	62	n += sprintf(map->addr[dir].dst + n, ":%u",
	63	ntohs(t->dst.u.udp.port));
	64	map->addr[dir].dstlen = n;
65	}
66	}
67
68	static int map_sip_addr(struct sk_buff **pskb, enum ip_conntrack_info ctinfo,
69	struct nf_conn ct, const char *dptr, size_t dlen,
70	enum sip_header_pos pos, struct addr_map *map)
71	{
72	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
73	unsigned int matchlen, matchoff, addrlen;
74	char *addr;
75
76	if (ct_sip_get_info(ct, *dptr, dlen, &matchoff, &matchlen, pos) <= 0)
77	return 1;
78
79	if ((matchlen == map->addr[dir].srciplen \|\|
80	matchlen == map->addr[dir].srclen) &&
81	memcmp(*dptr + matchoff, map->addr[dir].src, matchlen) == 0) {
82	addr = map->addr[!dir].dst;
83	addrlen = map->addr[!dir].dstlen;
84	} else if ((matchlen == map->addr[dir].dstiplen \|\|
85	matchlen == map->addr[dir].dstlen) &&
86	memcmp(*dptr + matchoff, map->addr[dir].dst, matchlen) == 0) {
87	addr = map->addr[!dir].src;
88	addrlen = map->addr[!dir].srclen;
89	} else
90	return 1;
91
92	if (!nf_nat_mangle_udp_packet(pskb, ct, ctinfo,
93	matchoff, matchlen, addr, addrlen))
94	return 0;
95	dptr = (pskb)->data + (pskb)->nh.iph->ihl4 + sizeof(struct udphdr);
96	return 1;
97
98	}
99
100	static unsigned int ip_nat_sip(struct sk_buff **pskb,
101	enum ip_conntrack_info ctinfo,
102	struct nf_conn *ct,
103	const char **dptr)
104	{
105	enum sip_header_pos pos;
106	struct addr_map map;
107	int dataoff, datalen;
108
109	dataoff = (pskb)->nh.iph->ihl4 + sizeof(struct udphdr);
110	datalen = (*pskb)->len - dataoff;
111	if (datalen < sizeof("SIP/2.0") - 1)
112	return NF_DROP;
113
114	addr_map_init(ct, &map);
115
116	/* Basic rules: requests and responses. */
117	if (strncmp(*dptr, "SIP/2.0", sizeof("SIP/2.0") - 1) != 0) {
118	/* 10.2: Constructing the REGISTER Request:
119	*
120	* The "userinfo" and "@" components of the SIP URI MUST NOT
121	* be present.
122	*/
123	if (datalen >= sizeof("REGISTER") - 1 &&
124	strncmp(*dptr, "REGISTER", sizeof("REGISTER") - 1) == 0)
125	pos = POS_REG_REQ_URI;
126	else
127	pos = POS_REQ_URI;
128
129	if (!map_sip_addr(pskb, ctinfo, ct, dptr, datalen, pos, &map))
130	return NF_DROP;
131	}
132
133	if (!map_sip_addr(pskb, ctinfo, ct, dptr, datalen, POS_FROM, &map) \|\|
134	!map_sip_addr(pskb, ctinfo, ct, dptr, datalen, POS_TO, &map) \|\|
135	!map_sip_addr(pskb, ctinfo, ct, dptr, datalen, POS_VIA, &map) \|\|
136	!map_sip_addr(pskb, ctinfo, ct, dptr, datalen, POS_CONTACT, &map))
137	return NF_DROP;
138	return NF_ACCEPT;
139	}
140
141	static unsigned int mangle_sip_packet(struct sk_buff **pskb,
142	enum ip_conntrack_info ctinfo,
143	struct nf_conn *ct,
144	const char **dptr, size_t dlen,
145	char *buffer, int bufflen,
146	enum sip_header_pos pos)
147	{
148	unsigned int matchlen, matchoff;
149
150	if (ct_sip_get_info(ct, *dptr, dlen, &matchoff, &matchlen, pos) <= 0)
151	return 0;
152
153	if (!nf_nat_mangle_udp_packet(pskb, ct, ctinfo,
154	matchoff, matchlen, buffer, bufflen))
155	return 0;
156
157	/* We need to reload this. Thanks Patrick. */
158	dptr = (pskb)->data + (pskb)->nh.iph->ihl4 + sizeof(struct udphdr);
159	return 1;
160	}
161
162	static int mangle_content_len(struct sk_buff **pskb,
163	enum ip_conntrack_info ctinfo,
164	struct nf_conn *ct,
165	const char *dptr)
166	{
167	unsigned int dataoff, matchoff, matchlen;
168	char buffer[sizeof("65536")];
169	int bufflen;
170
171	dataoff = (pskb)->nh.iph->ihl4 + sizeof(struct udphdr);
172
173	/* Get actual SDP lenght */
174	if (ct_sip_get_info(ct, dptr, (*pskb)->len - dataoff, &matchoff,
175	&matchlen, POS_SDP_HEADER) > 0) {
176
177	/* since ct_sip_get_info() give us a pointer passing 'v='
178	we need to add 2 bytes in this count. */
179	int c_len = (*pskb)->len - dataoff - matchoff + 2;
180
181	/* Now, update SDP length */
182	if (ct_sip_get_info(ct, dptr, (*pskb)->len - dataoff, &matchoff,
183	&matchlen, POS_CONTENT) > 0) {
184
185	bufflen = sprintf(buffer, "%u", c_len);
186	return nf_nat_mangle_udp_packet(pskb, ct, ctinfo,
187	matchoff, matchlen,
188	buffer, bufflen);
189	}
190	}
191	return 0;
192	}
193
194	static unsigned int mangle_sdp(struct sk_buff **pskb,
195	enum ip_conntrack_info ctinfo,
196	struct nf_conn *ct,
197	__be32 newip, u_int16_t port,
198	const char *dptr)
199	{
200	char buffer[sizeof("nnn.nnn.nnn.nnn")];
201	unsigned int dataoff, bufflen;
202
203	dataoff = (pskb)->nh.iph->ihl4 + sizeof(struct udphdr);
204
205	/* Mangle owner and contact info. */
206	bufflen = sprintf(buffer, "%u.%u.%u.%u", NIPQUAD(newip));
207	if (!mangle_sip_packet(pskb, ctinfo, ct, &dptr, (*pskb)->len - dataoff,
208	buffer, bufflen, POS_OWNER_IP4))
209	return 0;
210
211	if (!mangle_sip_packet(pskb, ctinfo, ct, &dptr, (*pskb)->len - dataoff,
212	buffer, bufflen, POS_CONNECTION_IP4))
213	return 0;
214
215	/* Mangle media port. */
216	bufflen = sprintf(buffer, "%u", port);
217	if (!mangle_sip_packet(pskb, ctinfo, ct, &dptr, (*pskb)->len - dataoff,
218	buffer, bufflen, POS_MEDIA))
219	return 0;
220
221	return mangle_content_len(pskb, ctinfo, ct, dptr);
222	}
223
224	/* So, this packet has hit the connection tracking matching code.
225	Mangle it, and change the expectation to match the new version. */
226	static unsigned int ip_nat_sdp(struct sk_buff **pskb,
227	enum ip_conntrack_info ctinfo,
228	struct nf_conntrack_expect *exp,
229	const char *dptr)
230	{
231	struct nf_conn *ct = exp->master;
232	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
233	__be32 newip;
234	u_int16_t port;
235
236	DEBUGP("ip_nat_sdp():\n");
237
238	/* Connection will come from reply */
239	newip = ct->tuplehash[!dir].tuple.dst.u3.ip;
240
241	exp->tuple.dst.u3.ip = newip;
242	exp->saved_proto.udp.port = exp->tuple.dst.u.udp.port;
243	exp->dir = !dir;
244
245	/* When you see the packet, we need to NAT it the same as the
246	this one. */
247	exp->expectfn = nf_nat_follow_master;
248
249	/* Try to get same port: if not, try to change it. */
250	for (port = ntohs(exp->saved_proto.udp.port); port != 0; port++) {
251	exp->tuple.dst.u.udp.port = htons(port);
252	if (nf_conntrack_expect_related(exp) == 0)
253	break;
254	}
255
256	if (port == 0)
257	return NF_DROP;
258
259	if (!mangle_sdp(pskb, ctinfo, ct, newip, port, dptr)) {
260	nf_conntrack_unexpect_related(exp);
261	return NF_DROP;
262	}
263	return NF_ACCEPT;
264	}
265
266	static void __exit nf_nat_sip_fini(void)
267	{
268	rcu_assign_pointer(nf_nat_sip_hook, NULL);
269	rcu_assign_pointer(nf_nat_sdp_hook, NULL);
270	synchronize_rcu();
271	}
272
273	static int __init nf_nat_sip_init(void)
274	{
275	BUG_ON(rcu_dereference(nf_nat_sip_hook));
276	BUG_ON(rcu_dereference(nf_nat_sdp_hook));
277	rcu_assign_pointer(nf_nat_sip_hook, ip_nat_sip);
278	rcu_assign_pointer(nf_nat_sdp_hook, ip_nat_sdp);
279	return 0;
280	}
281
282	module_init(nf_nat_sip_init);
283	module_exit(nf_nat_sip_fini);