// SPDX-License-Identifier: GPL-2.0-only
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/* SIP extension for 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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* (C) 2007 United Security Providers
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* (C) 2007, 2008, 2011, 2012 Patrick McHardy <kaber@trash.net>
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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/inet.h>
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#include <linux/udp.h>
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#include <linux/tcp.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_conntrack_core.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 <net/netfilter/nf_conntrack_seqadj.h>
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#include <linux/netfilter/nf_conntrack_sip.h>
|
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#define NAT_HELPER_NAME "sip"
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Christian Hentschel <chentschel@arnet.com.ar>");
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MODULE_DESCRIPTION("SIP NAT helper");
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MODULE_ALIAS_NF_NAT_HELPER(NAT_HELPER_NAME);
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static struct nf_conntrack_nat_helper nat_helper_sip =
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NF_CT_NAT_HELPER_INIT(NAT_HELPER_NAME);
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static unsigned int mangle_packet(struct sk_buff *skb, unsigned int protoff,
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unsigned int dataoff,
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const char **dptr, unsigned int *datalen,
|
unsigned int matchoff, unsigned int matchlen,
|
const char *buffer, unsigned int buflen)
|
{
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enum ip_conntrack_info ctinfo;
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struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
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struct tcphdr *th;
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unsigned int baseoff;
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if (nf_ct_protonum(ct) == IPPROTO_TCP) {
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th = (struct tcphdr *)(skb->data + protoff);
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baseoff = protoff + th->doff * 4;
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matchoff += dataoff - baseoff;
|
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if (!__nf_nat_mangle_tcp_packet(skb, ct, ctinfo,
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protoff, matchoff, matchlen,
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buffer, buflen, false))
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return 0;
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} else {
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baseoff = protoff + sizeof(struct udphdr);
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matchoff += dataoff - baseoff;
|
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if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo,
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protoff, matchoff, matchlen,
|
buffer, buflen))
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return 0;
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}
|
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/* Reload data pointer and adjust datalen value */
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*dptr = skb->data + dataoff;
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*datalen += buflen - matchlen;
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return 1;
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}
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static int sip_sprintf_addr(const struct nf_conn *ct, char *buffer,
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const union nf_inet_addr *addr, bool delim)
|
{
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if (nf_ct_l3num(ct) == NFPROTO_IPV4)
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return sprintf(buffer, "%pI4", &addr->ip);
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else {
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if (delim)
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return sprintf(buffer, "[%pI6c]", &addr->ip6);
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else
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return sprintf(buffer, "%pI6c", &addr->ip6);
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}
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}
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static int sip_sprintf_addr_port(const struct nf_conn *ct, char *buffer,
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const union nf_inet_addr *addr, u16 port)
|
{
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if (nf_ct_l3num(ct) == NFPROTO_IPV4)
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return sprintf(buffer, "%pI4:%u", &addr->ip, port);
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else
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return sprintf(buffer, "[%pI6c]:%u", &addr->ip6, port);
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}
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static int map_addr(struct sk_buff *skb, unsigned int protoff,
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unsigned int dataoff,
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const char **dptr, unsigned int *datalen,
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unsigned int matchoff, unsigned int matchlen,
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union nf_inet_addr *addr, __be16 port)
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{
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enum ip_conntrack_info ctinfo;
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struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
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enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
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struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
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char buffer[INET6_ADDRSTRLEN + sizeof("[]:nnnnn")];
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unsigned int buflen;
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union nf_inet_addr newaddr;
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__be16 newport;
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if (nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3, addr) &&
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ct->tuplehash[dir].tuple.src.u.udp.port == port) {
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newaddr = ct->tuplehash[!dir].tuple.dst.u3;
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newport = ct->tuplehash[!dir].tuple.dst.u.udp.port;
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} else if (nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3, addr) &&
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ct->tuplehash[dir].tuple.dst.u.udp.port == port) {
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newaddr = ct->tuplehash[!dir].tuple.src.u3;
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newport = ct_sip_info->forced_dport ? :
|
ct->tuplehash[!dir].tuple.src.u.udp.port;
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} else
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return 1;
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if (nf_inet_addr_cmp(&newaddr, addr) && newport == port)
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return 1;
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buflen = sip_sprintf_addr_port(ct, buffer, &newaddr, ntohs(newport));
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return mangle_packet(skb, protoff, dataoff, dptr, datalen,
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matchoff, matchlen, buffer, buflen);
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}
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static int map_sip_addr(struct sk_buff *skb, unsigned int protoff,
|
unsigned int dataoff,
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const char **dptr, unsigned int *datalen,
|
enum sip_header_types type)
|
{
|
enum ip_conntrack_info ctinfo;
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struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
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unsigned int matchlen, matchoff;
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union nf_inet_addr addr;
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__be16 port;
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if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen, type, NULL,
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&matchoff, &matchlen, &addr, &port) <= 0)
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return 1;
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return map_addr(skb, protoff, dataoff, dptr, datalen,
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matchoff, matchlen, &addr, port);
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}
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static unsigned int nf_nat_sip(struct sk_buff *skb, unsigned int protoff,
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unsigned int dataoff,
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const char **dptr, unsigned int *datalen)
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{
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enum ip_conntrack_info ctinfo;
|
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
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enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
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struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
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unsigned int coff, matchoff, matchlen;
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enum sip_header_types hdr;
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union nf_inet_addr addr;
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__be16 port;
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int request, in_header;
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/* Basic rules: requests and responses. */
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if (strncasecmp(*dptr, "SIP/2.0", strlen("SIP/2.0")) != 0) {
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if (ct_sip_parse_request(ct, *dptr, *datalen,
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&matchoff, &matchlen,
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&addr, &port) > 0 &&
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!map_addr(skb, protoff, dataoff, dptr, datalen,
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matchoff, matchlen, &addr, port)) {
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nf_ct_helper_log(skb, ct, "cannot mangle SIP message");
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return NF_DROP;
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}
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request = 1;
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} else
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request = 0;
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if (nf_ct_protonum(ct) == IPPROTO_TCP)
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hdr = SIP_HDR_VIA_TCP;
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else
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hdr = SIP_HDR_VIA_UDP;
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/* Translate topmost Via header and parameters */
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if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen,
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hdr, NULL, &matchoff, &matchlen,
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&addr, &port) > 0) {
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unsigned int olen, matchend, poff, plen, buflen, n;
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char buffer[INET6_ADDRSTRLEN + sizeof("[]:nnnnn")];
|
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/* We're only interested in headers related to this
|
* connection */
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if (request) {
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if (!nf_inet_addr_cmp(&addr,
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&ct->tuplehash[dir].tuple.src.u3) ||
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port != ct->tuplehash[dir].tuple.src.u.udp.port)
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goto next;
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} else {
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if (!nf_inet_addr_cmp(&addr,
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&ct->tuplehash[dir].tuple.dst.u3) ||
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port != ct->tuplehash[dir].tuple.dst.u.udp.port)
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goto next;
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}
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olen = *datalen;
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if (!map_addr(skb, protoff, dataoff, dptr, datalen,
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matchoff, matchlen, &addr, port)) {
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nf_ct_helper_log(skb, ct, "cannot mangle Via header");
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return NF_DROP;
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}
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matchend = matchoff + matchlen + *datalen - olen;
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/* The maddr= parameter (RFC 2361) specifies where to send
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* the reply. */
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if (ct_sip_parse_address_param(ct, *dptr, matchend, *datalen,
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"maddr=", &poff, &plen,
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&addr, true) > 0 &&
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nf_inet_addr_cmp(&addr, &ct->tuplehash[dir].tuple.src.u3) &&
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!nf_inet_addr_cmp(&addr, &ct->tuplehash[!dir].tuple.dst.u3)) {
|
buflen = sip_sprintf_addr(ct, buffer,
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&ct->tuplehash[!dir].tuple.dst.u3,
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true);
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if (!mangle_packet(skb, protoff, dataoff, dptr, datalen,
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poff, plen, buffer, buflen)) {
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nf_ct_helper_log(skb, ct, "cannot mangle maddr");
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return NF_DROP;
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}
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}
|
|
/* The received= parameter (RFC 2361) contains the address
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* from which the server received the request. */
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if (ct_sip_parse_address_param(ct, *dptr, matchend, *datalen,
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"received=", &poff, &plen,
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&addr, false) > 0 &&
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nf_inet_addr_cmp(&addr, &ct->tuplehash[dir].tuple.dst.u3) &&
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!nf_inet_addr_cmp(&addr, &ct->tuplehash[!dir].tuple.src.u3)) {
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buflen = sip_sprintf_addr(ct, buffer,
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&ct->tuplehash[!dir].tuple.src.u3,
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false);
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if (!mangle_packet(skb, protoff, dataoff, dptr, datalen,
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poff, plen, buffer, buflen)) {
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nf_ct_helper_log(skb, ct, "cannot mangle received");
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return NF_DROP;
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}
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}
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/* The rport= parameter (RFC 3581) contains the port number
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* from which the server received the request. */
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if (ct_sip_parse_numerical_param(ct, *dptr, matchend, *datalen,
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"rport=", &poff, &plen,
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&n) > 0 &&
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htons(n) == ct->tuplehash[dir].tuple.dst.u.udp.port &&
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htons(n) != ct->tuplehash[!dir].tuple.src.u.udp.port) {
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__be16 p = ct->tuplehash[!dir].tuple.src.u.udp.port;
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buflen = sprintf(buffer, "%u", ntohs(p));
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if (!mangle_packet(skb, protoff, dataoff, dptr, datalen,
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poff, plen, buffer, buflen)) {
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nf_ct_helper_log(skb, ct, "cannot mangle rport");
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return NF_DROP;
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}
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}
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}
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|
next:
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/* Translate Contact headers */
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coff = 0;
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in_header = 0;
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while (ct_sip_parse_header_uri(ct, *dptr, &coff, *datalen,
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SIP_HDR_CONTACT, &in_header,
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&matchoff, &matchlen,
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&addr, &port) > 0) {
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if (!map_addr(skb, protoff, dataoff, dptr, datalen,
|
matchoff, matchlen,
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&addr, port)) {
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nf_ct_helper_log(skb, ct, "cannot mangle contact");
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return NF_DROP;
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}
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}
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if (!map_sip_addr(skb, protoff, dataoff, dptr, datalen, SIP_HDR_FROM) ||
|
!map_sip_addr(skb, protoff, dataoff, dptr, datalen, SIP_HDR_TO)) {
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nf_ct_helper_log(skb, ct, "cannot mangle SIP from/to");
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return NF_DROP;
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}
|
|
/* Mangle destination port for Cisco phones, then fix up checksums */
|
if (dir == IP_CT_DIR_REPLY && ct_sip_info->forced_dport) {
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struct udphdr *uh;
|
|
if (skb_ensure_writable(skb, skb->len)) {
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nf_ct_helper_log(skb, ct, "cannot mangle packet");
|
return NF_DROP;
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}
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|
uh = (void *)skb->data + protoff;
|
uh->dest = ct_sip_info->forced_dport;
|
|
if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo, protoff,
|
0, 0, NULL, 0)) {
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nf_ct_helper_log(skb, ct, "cannot mangle packet");
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return NF_DROP;
|
}
|
}
|
|
return NF_ACCEPT;
|
}
|
|
static void nf_nat_sip_seq_adjust(struct sk_buff *skb, unsigned int protoff,
|
s16 off)
|
{
|
enum ip_conntrack_info ctinfo;
|
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
|
const struct tcphdr *th;
|
|
if (nf_ct_protonum(ct) != IPPROTO_TCP || off == 0)
|
return;
|
|
th = (struct tcphdr *)(skb->data + protoff);
|
nf_ct_seqadj_set(ct, ctinfo, th->seq, off);
|
}
|
|
/* Handles expected signalling connections and media streams */
|
static void nf_nat_sip_expected(struct nf_conn *ct,
|
struct nf_conntrack_expect *exp)
|
{
|
struct nf_conn_help *help = nfct_help(ct->master);
|
struct nf_conntrack_expect *pair_exp;
|
int range_set_for_snat = 0;
|
struct nf_nat_range2 range;
|
|
/* This must be a fresh one. */
|
BUG_ON(ct->status & IPS_NAT_DONE_MASK);
|
|
/* For DST manip, map port here to where it's expected. */
|
range.flags = (NF_NAT_RANGE_MAP_IPS | NF_NAT_RANGE_PROTO_SPECIFIED);
|
range.min_proto = range.max_proto = exp->saved_proto;
|
range.min_addr = range.max_addr = exp->saved_addr;
|
nf_nat_setup_info(ct, &range, NF_NAT_MANIP_DST);
|
|
/* Do media streams SRC manip according with the parameters
|
* found in the paired expectation.
|
*/
|
if (exp->class != SIP_EXPECT_SIGNALLING) {
|
spin_lock_bh(&nf_conntrack_expect_lock);
|
hlist_for_each_entry(pair_exp, &help->expectations, lnode) {
|
if (pair_exp->tuple.src.l3num == nf_ct_l3num(ct) &&
|
pair_exp->tuple.dst.protonum == ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum &&
|
nf_inet_addr_cmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3, &pair_exp->saved_addr) &&
|
ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.all == pair_exp->saved_proto.all) {
|
range.flags = (NF_NAT_RANGE_MAP_IPS | NF_NAT_RANGE_PROTO_SPECIFIED);
|
range.min_proto.all = range.max_proto.all = pair_exp->tuple.dst.u.all;
|
range.min_addr = range.max_addr = pair_exp->tuple.dst.u3;
|
range_set_for_snat = 1;
|
break;
|
}
|
}
|
spin_unlock_bh(&nf_conntrack_expect_lock);
|
}
|
|
/* When no paired expectation has been found, change src to
|
* where master sends to, but only if the connection actually came
|
* from the same source.
|
*/
|
if (!range_set_for_snat &&
|
nf_inet_addr_cmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3,
|
&ct->master->tuplehash[exp->dir].tuple.src.u3)) {
|
range.flags = NF_NAT_RANGE_MAP_IPS;
|
range.min_addr = range.max_addr
|
= ct->master->tuplehash[!exp->dir].tuple.dst.u3;
|
range_set_for_snat = 1;
|
}
|
|
/* Perform SRC manip. */
|
if (range_set_for_snat)
|
nf_nat_setup_info(ct, &range, NF_NAT_MANIP_SRC);
|
}
|
|
static unsigned int nf_nat_sip_expect(struct sk_buff *skb, unsigned int protoff,
|
unsigned int dataoff,
|
const char **dptr, unsigned int *datalen,
|
struct nf_conntrack_expect *exp,
|
unsigned int matchoff,
|
unsigned int matchlen)
|
{
|
enum ip_conntrack_info ctinfo;
|
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
|
enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
|
struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
|
union nf_inet_addr newaddr;
|
u_int16_t port;
|
__be16 srcport;
|
char buffer[INET6_ADDRSTRLEN + sizeof("[]:nnnnn")];
|
unsigned int buflen;
|
|
/* Connection will come from reply */
|
if (nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3,
|
&ct->tuplehash[!dir].tuple.dst.u3))
|
newaddr = exp->tuple.dst.u3;
|
else
|
newaddr = ct->tuplehash[!dir].tuple.dst.u3;
|
|
/* If the signalling port matches the connection's source port in the
|
* original direction, try to use the destination port in the opposite
|
* direction. */
|
srcport = ct_sip_info->forced_dport ? :
|
ct->tuplehash[dir].tuple.src.u.udp.port;
|
if (exp->tuple.dst.u.udp.port == srcport)
|
port = ntohs(ct->tuplehash[!dir].tuple.dst.u.udp.port);
|
else
|
port = ntohs(exp->tuple.dst.u.udp.port);
|
|
exp->saved_addr = exp->tuple.dst.u3;
|
exp->tuple.dst.u3 = newaddr;
|
exp->saved_proto.udp.port = exp->tuple.dst.u.udp.port;
|
exp->dir = !dir;
|
exp->expectfn = nf_nat_sip_expected;
|
|
for (; port != 0; port++) {
|
int ret;
|
|
exp->tuple.dst.u.udp.port = htons(port);
|
ret = nf_ct_expect_related(exp, NF_CT_EXP_F_SKIP_MASTER);
|
if (ret == 0)
|
break;
|
else if (ret != -EBUSY) {
|
port = 0;
|
break;
|
}
|
}
|
|
if (port == 0) {
|
nf_ct_helper_log(skb, ct, "all ports in use for SIP");
|
return NF_DROP;
|
}
|
|
if (!nf_inet_addr_cmp(&exp->tuple.dst.u3, &exp->saved_addr) ||
|
exp->tuple.dst.u.udp.port != exp->saved_proto.udp.port) {
|
buflen = sip_sprintf_addr_port(ct, buffer, &newaddr, port);
|
if (!mangle_packet(skb, protoff, dataoff, dptr, datalen,
|
matchoff, matchlen, buffer, buflen)) {
|
nf_ct_helper_log(skb, ct, "cannot mangle packet");
|
goto err;
|
}
|
}
|
return NF_ACCEPT;
|
|
err:
|
nf_ct_unexpect_related(exp);
|
return NF_DROP;
|
}
|
|
static int mangle_content_len(struct sk_buff *skb, unsigned int protoff,
|
unsigned int dataoff,
|
const char **dptr, unsigned int *datalen)
|
{
|
enum ip_conntrack_info ctinfo;
|
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
|
unsigned int matchoff, matchlen;
|
char buffer[sizeof("65536")];
|
int buflen, c_len;
|
|
/* Get actual SDP length */
|
if (ct_sip_get_sdp_header(ct, *dptr, 0, *datalen,
|
SDP_HDR_VERSION, SDP_HDR_UNSPEC,
|
&matchoff, &matchlen) <= 0)
|
return 0;
|
c_len = *datalen - matchoff + strlen("v=");
|
|
/* Now, update SDP length */
|
if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CONTENT_LENGTH,
|
&matchoff, &matchlen) <= 0)
|
return 0;
|
|
buflen = sprintf(buffer, "%u", c_len);
|
return mangle_packet(skb, protoff, dataoff, dptr, datalen,
|
matchoff, matchlen, buffer, buflen);
|
}
|
|
static int mangle_sdp_packet(struct sk_buff *skb, unsigned int protoff,
|
unsigned int dataoff,
|
const char **dptr, unsigned int *datalen,
|
unsigned int sdpoff,
|
enum sdp_header_types type,
|
enum sdp_header_types term,
|
char *buffer, int buflen)
|
{
|
enum ip_conntrack_info ctinfo;
|
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
|
unsigned int matchlen, matchoff;
|
|
if (ct_sip_get_sdp_header(ct, *dptr, sdpoff, *datalen, type, term,
|
&matchoff, &matchlen) <= 0)
|
return -ENOENT;
|
return mangle_packet(skb, protoff, dataoff, dptr, datalen,
|
matchoff, matchlen, buffer, buflen) ? 0 : -EINVAL;
|
}
|
|
static unsigned int nf_nat_sdp_addr(struct sk_buff *skb, unsigned int protoff,
|
unsigned int dataoff,
|
const char **dptr, unsigned int *datalen,
|
unsigned int sdpoff,
|
enum sdp_header_types type,
|
enum sdp_header_types term,
|
const union nf_inet_addr *addr)
|
{
|
enum ip_conntrack_info ctinfo;
|
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
|
char buffer[INET6_ADDRSTRLEN];
|
unsigned int buflen;
|
|
buflen = sip_sprintf_addr(ct, buffer, addr, false);
|
if (mangle_sdp_packet(skb, protoff, dataoff, dptr, datalen,
|
sdpoff, type, term, buffer, buflen))
|
return 0;
|
|
return mangle_content_len(skb, protoff, dataoff, dptr, datalen);
|
}
|
|
static unsigned int nf_nat_sdp_port(struct sk_buff *skb, unsigned int protoff,
|
unsigned int dataoff,
|
const char **dptr, unsigned int *datalen,
|
unsigned int matchoff,
|
unsigned int matchlen,
|
u_int16_t port)
|
{
|
char buffer[sizeof("nnnnn")];
|
unsigned int buflen;
|
|
buflen = sprintf(buffer, "%u", port);
|
if (!mangle_packet(skb, protoff, dataoff, dptr, datalen,
|
matchoff, matchlen, buffer, buflen))
|
return 0;
|
|
return mangle_content_len(skb, protoff, dataoff, dptr, datalen);
|
}
|
|
static unsigned int nf_nat_sdp_session(struct sk_buff *skb, unsigned int protoff,
|
unsigned int dataoff,
|
const char **dptr, unsigned int *datalen,
|
unsigned int sdpoff,
|
const union nf_inet_addr *addr)
|
{
|
enum ip_conntrack_info ctinfo;
|
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
|
char buffer[INET6_ADDRSTRLEN];
|
unsigned int buflen;
|
|
/* Mangle session description owner and contact addresses */
|
buflen = sip_sprintf_addr(ct, buffer, addr, false);
|
if (mangle_sdp_packet(skb, protoff, dataoff, dptr, datalen, sdpoff,
|
SDP_HDR_OWNER, SDP_HDR_MEDIA, buffer, buflen))
|
return 0;
|
|
switch (mangle_sdp_packet(skb, protoff, dataoff, dptr, datalen, sdpoff,
|
SDP_HDR_CONNECTION, SDP_HDR_MEDIA,
|
buffer, buflen)) {
|
case 0:
|
/*
|
* RFC 2327:
|
*
|
* Session description
|
*
|
* c=* (connection information - not required if included in all media)
|
*/
|
case -ENOENT:
|
break;
|
default:
|
return 0;
|
}
|
|
return mangle_content_len(skb, protoff, dataoff, dptr, datalen);
|
}
|
|
/* So, this packet has hit the connection tracking matching code.
|
Mangle it, and change the expectation to match the new version. */
|
static unsigned int nf_nat_sdp_media(struct sk_buff *skb, unsigned int protoff,
|
unsigned int dataoff,
|
const char **dptr, unsigned int *datalen,
|
struct nf_conntrack_expect *rtp_exp,
|
struct nf_conntrack_expect *rtcp_exp,
|
unsigned int mediaoff,
|
unsigned int medialen,
|
union nf_inet_addr *rtp_addr)
|
{
|
enum ip_conntrack_info ctinfo;
|
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
|
enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
|
u_int16_t port;
|
|
/* Connection will come from reply */
|
if (nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3,
|
&ct->tuplehash[!dir].tuple.dst.u3))
|
*rtp_addr = rtp_exp->tuple.dst.u3;
|
else
|
*rtp_addr = ct->tuplehash[!dir].tuple.dst.u3;
|
|
rtp_exp->saved_addr = rtp_exp->tuple.dst.u3;
|
rtp_exp->tuple.dst.u3 = *rtp_addr;
|
rtp_exp->saved_proto.udp.port = rtp_exp->tuple.dst.u.udp.port;
|
rtp_exp->dir = !dir;
|
rtp_exp->expectfn = nf_nat_sip_expected;
|
|
rtcp_exp->saved_addr = rtcp_exp->tuple.dst.u3;
|
rtcp_exp->tuple.dst.u3 = *rtp_addr;
|
rtcp_exp->saved_proto.udp.port = rtcp_exp->tuple.dst.u.udp.port;
|
rtcp_exp->dir = !dir;
|
rtcp_exp->expectfn = nf_nat_sip_expected;
|
|
/* Try to get same pair of ports: if not, try to change them. */
|
for (port = ntohs(rtp_exp->tuple.dst.u.udp.port);
|
port != 0; port += 2) {
|
int ret;
|
|
rtp_exp->tuple.dst.u.udp.port = htons(port);
|
ret = nf_ct_expect_related(rtp_exp,
|
NF_CT_EXP_F_SKIP_MASTER);
|
if (ret == -EBUSY)
|
continue;
|
else if (ret < 0) {
|
port = 0;
|
break;
|
}
|
rtcp_exp->tuple.dst.u.udp.port = htons(port + 1);
|
ret = nf_ct_expect_related(rtcp_exp,
|
NF_CT_EXP_F_SKIP_MASTER);
|
if (ret == 0)
|
break;
|
else if (ret == -EBUSY) {
|
nf_ct_unexpect_related(rtp_exp);
|
continue;
|
} else if (ret < 0) {
|
nf_ct_unexpect_related(rtp_exp);
|
port = 0;
|
break;
|
}
|
}
|
|
if (port == 0) {
|
nf_ct_helper_log(skb, ct, "all ports in use for SDP media");
|
goto err1;
|
}
|
|
/* Update media port. */
|
if (rtp_exp->tuple.dst.u.udp.port != rtp_exp->saved_proto.udp.port &&
|
!nf_nat_sdp_port(skb, protoff, dataoff, dptr, datalen,
|
mediaoff, medialen, port)) {
|
nf_ct_helper_log(skb, ct, "cannot mangle SDP message");
|
goto err2;
|
}
|
|
return NF_ACCEPT;
|
|
err2:
|
nf_ct_unexpect_related(rtp_exp);
|
nf_ct_unexpect_related(rtcp_exp);
|
err1:
|
return NF_DROP;
|
}
|
|
static struct nf_ct_helper_expectfn sip_nat = {
|
.name = "sip",
|
.expectfn = nf_nat_sip_expected,
|
};
|
|
static void __exit nf_nat_sip_fini(void)
|
{
|
nf_nat_helper_unregister(&nat_helper_sip);
|
RCU_INIT_POINTER(nf_nat_sip_hooks, NULL);
|
nf_ct_helper_expectfn_unregister(&sip_nat);
|
synchronize_rcu();
|
}
|
|
static const struct nf_nat_sip_hooks sip_hooks = {
|
.msg = nf_nat_sip,
|
.seq_adjust = nf_nat_sip_seq_adjust,
|
.expect = nf_nat_sip_expect,
|
.sdp_addr = nf_nat_sdp_addr,
|
.sdp_port = nf_nat_sdp_port,
|
.sdp_session = nf_nat_sdp_session,
|
.sdp_media = nf_nat_sdp_media,
|
};
|
|
static int __init nf_nat_sip_init(void)
|
{
|
BUG_ON(nf_nat_sip_hooks != NULL);
|
nf_nat_helper_register(&nat_helper_sip);
|
RCU_INIT_POINTER(nf_nat_sip_hooks, &sip_hooks);
|
nf_ct_helper_expectfn_register(&sip_nat);
|
return 0;
|
}
|
|
module_init(nf_nat_sip_init);
|
module_exit(nf_nat_sip_fini);
|
