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[NETFILTER]: nf_conntrack/nf_nat: add SIP helper port
Add IPv4 and IPv6 capable nf_conntrack port of the SIP conntrack/NAT helper. Signed-off-by: Patrick McHardy <[email protected]> Signed-off-by: David S. Miller <[email protected]>
This commit is contained in:
Patrick McHardy
David S. Miller
parent
f09943fefe
commit
9fafcd7b20
7 changed files with 873 additions and 0 deletions
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@ -555,6 +555,11 @@ config IP_NF_NAT_SIP
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default IP_NF_NAT if IP_NF_SIP=y
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default m if IP_NF_SIP=m
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config NF_NAT_SIP
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tristate
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depends on IP_NF_IPTABLES && NF_CONNTRACK && NF_NAT
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default NF_NAT && NF_CONNTRACK_SIP
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# mangle + specific targets
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config IP_NF_MANGLE
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tristate "Packet mangling"
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@ -55,6 +55,7 @@ obj-$(CONFIG_NF_NAT_FTP) += nf_nat_ftp.o
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obj-$(CONFIG_NF_NAT_H323) += nf_nat_h323.o
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obj-$(CONFIG_NF_NAT_IRC) += nf_nat_irc.o
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obj-$(CONFIG_NF_NAT_PPTP) += nf_nat_pptp.o
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obj-$(CONFIG_NF_NAT_SIP) += nf_nat_sip.o
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# NAT protocols (nf_nat)
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obj-$(CONFIG_NF_NAT_PROTO_GRE) += nf_nat_proto_gre.o
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283
net/ipv4/netfilter/nf_nat_sip.c
Normal file
283
net/ipv4/netfilter/nf_nat_sip.c
Normal file
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@ -0,0 +1,283 @@
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/* SIP extension for UDP NAT alteration.
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*
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* (C) 2005 by Christian Hentschel <chentschel@arnet.com.ar>
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* based on RR's ip_nat_ftp.c and other modules.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <linux/ip.h>
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#include <linux/udp.h>
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#include <net/netfilter/nf_nat.h>
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#include <net/netfilter/nf_nat_helper.h>
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#include <net/netfilter/nf_nat_rule.h>
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#include <net/netfilter/nf_conntrack_helper.h>
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#include <net/netfilter/nf_conntrack_expect.h>
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#include <linux/netfilter/nf_conntrack_sip.h>
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Christian Hentschel <[email protected]>");
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MODULE_DESCRIPTION("SIP NAT helper");
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MODULE_ALIAS("ip_nat_sip");
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#if 0
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#define DEBUGP printk
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#else
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#define DEBUGP(format, args...)
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#endif
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struct addr_map {
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struct {
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char src[sizeof("nnn.nnn.nnn.nnn:nnnnn")];
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char dst[sizeof("nnn.nnn.nnn.nnn:nnnnn")];
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unsigned int srclen, srciplen;
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unsigned int dstlen, dstiplen;
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} addr[IP_CT_DIR_MAX];
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};
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static void addr_map_init(struct nf_conn *ct, struct addr_map *map)
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{
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struct nf_conntrack_tuple *t;
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enum ip_conntrack_dir dir;
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unsigned int n;
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for (dir = 0; dir < IP_CT_DIR_MAX; dir++) {
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t = &ct->tuplehash[dir].tuple;
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n = sprintf(map->addr[dir].src, "%u.%u.%u.%u",
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NIPQUAD(t->src.u3.ip));
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map->addr[dir].srciplen = n;
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n += sprintf(map->addr[dir].src + n, ":%u",
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ntohs(t->src.u.udp.port));
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map->addr[dir].srclen = n;
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n = sprintf(map->addr[dir].dst, "%u.%u.%u.%u",
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NIPQUAD(t->dst.u3.ip));
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map->addr[dir].dstiplen = n;
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n += sprintf(map->addr[dir].dst + n, ":%u",
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ntohs(t->dst.u.udp.port));
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map->addr[dir].dstlen = n;
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}
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}
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static int map_sip_addr(struct sk_buff **pskb, enum ip_conntrack_info ctinfo,
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struct nf_conn *ct, const char **dptr, size_t dlen,
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enum sip_header_pos pos, struct addr_map *map)
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{
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enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
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unsigned int matchlen, matchoff, addrlen;
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char *addr;
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if (ct_sip_get_info(ct, *dptr, dlen, &matchoff, &matchlen, pos) <= 0)
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return 1;
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if ((matchlen == map->addr[dir].srciplen ||
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matchlen == map->addr[dir].srclen) &&
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memcmp(*dptr + matchoff, map->addr[dir].src, matchlen) == 0) {
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addr = map->addr[!dir].dst;
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addrlen = map->addr[!dir].dstlen;
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} else if ((matchlen == map->addr[dir].dstiplen ||
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matchlen == map->addr[dir].dstlen) &&
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memcmp(*dptr + matchoff, map->addr[dir].dst, matchlen) == 0) {
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addr = map->addr[!dir].src;
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addrlen = map->addr[!dir].srclen;
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} else
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return 1;
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if (!nf_nat_mangle_udp_packet(pskb, ct, ctinfo,
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matchoff, matchlen, addr, addrlen))
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return 0;
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*dptr = (*pskb)->data + (*pskb)->nh.iph->ihl*4 + sizeof(struct udphdr);
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return 1;
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}
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static unsigned int ip_nat_sip(struct sk_buff **pskb,
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enum ip_conntrack_info ctinfo,
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struct nf_conn *ct,
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const char **dptr)
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{
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enum sip_header_pos pos;
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struct addr_map map;
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int dataoff, datalen;
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dataoff = (*pskb)->nh.iph->ihl*4 + sizeof(struct udphdr);
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datalen = (*pskb)->len - dataoff;
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if (datalen < sizeof("SIP/2.0") - 1)
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return NF_DROP;
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addr_map_init(ct, &map);
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/* Basic rules: requests and responses. */
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if (strncmp(*dptr, "SIP/2.0", sizeof("SIP/2.0") - 1) != 0) {
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/* 10.2: Constructing the REGISTER Request:
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*
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* The "userinfo" and "@" components of the SIP URI MUST NOT
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* be present.
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*/
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if (datalen >= sizeof("REGISTER") - 1 &&
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strncmp(*dptr, "REGISTER", sizeof("REGISTER") - 1) == 0)
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pos = POS_REG_REQ_URI;
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else
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pos = POS_REQ_URI;
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if (!map_sip_addr(pskb, ctinfo, ct, dptr, datalen, pos, &map))
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return NF_DROP;
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}
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if (!map_sip_addr(pskb, ctinfo, ct, dptr, datalen, POS_FROM, &map) ||
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!map_sip_addr(pskb, ctinfo, ct, dptr, datalen, POS_TO, &map) ||
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!map_sip_addr(pskb, ctinfo, ct, dptr, datalen, POS_VIA, &map) ||
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!map_sip_addr(pskb, ctinfo, ct, dptr, datalen, POS_CONTACT, &map))
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return NF_DROP;
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return NF_ACCEPT;
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}
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static unsigned int mangle_sip_packet(struct sk_buff **pskb,
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enum ip_conntrack_info ctinfo,
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struct nf_conn *ct,
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const char **dptr, size_t dlen,
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char *buffer, int bufflen,
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enum sip_header_pos pos)
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{
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unsigned int matchlen, matchoff;
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if (ct_sip_get_info(ct, *dptr, dlen, &matchoff, &matchlen, pos) <= 0)
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return 0;
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if (!nf_nat_mangle_udp_packet(pskb, ct, ctinfo,
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matchoff, matchlen, buffer, bufflen))
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return 0;
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/* We need to reload this. Thanks Patrick. */
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*dptr = (*pskb)->data + (*pskb)->nh.iph->ihl*4 + sizeof(struct udphdr);
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return 1;
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}
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static int mangle_content_len(struct sk_buff **pskb,
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enum ip_conntrack_info ctinfo,
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struct nf_conn *ct,
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const char *dptr)
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{
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unsigned int dataoff, matchoff, matchlen;
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char buffer[sizeof("65536")];
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int bufflen;
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dataoff = (*pskb)->nh.iph->ihl*4 + sizeof(struct udphdr);
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/* Get actual SDP lenght */
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if (ct_sip_get_info(ct, dptr, (*pskb)->len - dataoff, &matchoff,
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&matchlen, POS_SDP_HEADER) > 0) {
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/* since ct_sip_get_info() give us a pointer passing 'v='
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we need to add 2 bytes in this count. */
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int c_len = (*pskb)->len - dataoff - matchoff + 2;
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/* Now, update SDP length */
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if (ct_sip_get_info(ct, dptr, (*pskb)->len - dataoff, &matchoff,
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&matchlen, POS_CONTENT) > 0) {
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bufflen = sprintf(buffer, "%u", c_len);
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return nf_nat_mangle_udp_packet(pskb, ct, ctinfo,
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matchoff, matchlen,
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buffer, bufflen);
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}
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}
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return 0;
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}
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static unsigned int mangle_sdp(struct sk_buff **pskb,
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enum ip_conntrack_info ctinfo,
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struct nf_conn *ct,
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__be32 newip, u_int16_t port,
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const char *dptr)
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{
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char buffer[sizeof("nnn.nnn.nnn.nnn")];
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unsigned int dataoff, bufflen;
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dataoff = (*pskb)->nh.iph->ihl*4 + sizeof(struct udphdr);
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/* Mangle owner and contact info. */
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bufflen = sprintf(buffer, "%u.%u.%u.%u", NIPQUAD(newip));
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if (!mangle_sip_packet(pskb, ctinfo, ct, &dptr, (*pskb)->len - dataoff,
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buffer, bufflen, POS_OWNER_IP4))
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return 0;
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if (!mangle_sip_packet(pskb, ctinfo, ct, &dptr, (*pskb)->len - dataoff,
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buffer, bufflen, POS_CONNECTION_IP4))
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return 0;
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/* Mangle media port. */
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bufflen = sprintf(buffer, "%u", port);
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if (!mangle_sip_packet(pskb, ctinfo, ct, &dptr, (*pskb)->len - dataoff,
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buffer, bufflen, POS_MEDIA))
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return 0;
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return mangle_content_len(pskb, ctinfo, ct, dptr);
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}
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/* So, this packet has hit the connection tracking matching code.
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Mangle it, and change the expectation to match the new version. */
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static unsigned int ip_nat_sdp(struct sk_buff **pskb,
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enum ip_conntrack_info ctinfo,
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struct nf_conntrack_expect *exp,
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const char *dptr)
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{
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struct nf_conn *ct = exp->master;
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enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
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__be32 newip;
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u_int16_t port;
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DEBUGP("ip_nat_sdp():\n");
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/* Connection will come from reply */
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newip = ct->tuplehash[!dir].tuple.dst.u3.ip;
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exp->tuple.dst.u3.ip = newip;
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exp->saved_proto.udp.port = exp->tuple.dst.u.udp.port;
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exp->dir = !dir;
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/* When you see the packet, we need to NAT it the same as the
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this one. */
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exp->expectfn = nf_nat_follow_master;
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/* Try to get same port: if not, try to change it. */
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for (port = ntohs(exp->saved_proto.udp.port); port != 0; port++) {
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exp->tuple.dst.u.udp.port = htons(port);
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if (nf_conntrack_expect_related(exp) == 0)
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break;
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}
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if (port == 0)
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return NF_DROP;
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if (!mangle_sdp(pskb, ctinfo, ct, newip, port, dptr)) {
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nf_conntrack_unexpect_related(exp);
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return NF_DROP;
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}
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return NF_ACCEPT;
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}
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static void __exit nf_nat_sip_fini(void)
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{
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rcu_assign_pointer(nf_nat_sip_hook, NULL);
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rcu_assign_pointer(nf_nat_sdp_hook, NULL);
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synchronize_rcu();
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}
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static int __init nf_nat_sip_init(void)
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{
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BUG_ON(rcu_dereference(nf_nat_sip_hook));
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BUG_ON(rcu_dereference(nf_nat_sdp_hook));
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rcu_assign_pointer(nf_nat_sip_hook, ip_nat_sip);
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rcu_assign_pointer(nf_nat_sdp_hook, ip_nat_sdp);
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return 0;
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}
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module_init(nf_nat_sip_init);
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module_exit(nf_nat_sip_fini);
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