Eric Lee / smarc-ti-linux-kernel

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Commit 7266507d89991fa1e989283e4e032c6d9357fe26

Authored by Kevin Cernekee
Committed by Pablo Neira Ayuso
1 parent 247fa82be1
Exists in master and in 20 other branches dlt-processor-sdk-linux-03.00.00.04, newt-ti-linux-3.12.y, processor-sdk-linux-01.00.00, processor-sdk-linux-02.00.01, smarc-ti-linux-3.12.10, smarc-ti-linux-3.12.y, smarc-ti-linux-3.14.y, smarc-ti-linux-3.15.y, smarc-ti-lsk-linux-4.1.y, smarct3x-processor-sdk-04.01.00.06, smarct3x-processor-sdk-linux-02.00.01, smarct3x-processor-sdk-linux-03.00.00.04, smarct4x-800-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-04.01.00.06, smarct4x-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-linux-03.00.00.04, ti-linux-3.12.y, ti-linux-3.14.y, ti-linux-3.15.y, ti-lsk-linux-4.1.y

netfilter: nf_ct_sip: support Cisco 7941/7945 IP phones 

Most SIP devices use a source port of 5060/udp on SIP requests, so the
response automatically comes back to port 5060:

    phone_ip:5060 -> proxy_ip:5060   REGISTER
    proxy_ip:5060 -> phone_ip:5060   100 Trying

The newer Cisco IP phones, however, use a randomly chosen high source
port for the SIP request but expect the response on port 5060:

    phone_ip:49173 -> proxy_ip:5060  REGISTER
    proxy_ip:5060 -> phone_ip:5060   100 Trying

Standard Linux NAT, with or without nf_nat_sip, will send the reply back
to port 49173, not 5060:

    phone_ip:49173 -> proxy_ip:5060  REGISTER
    proxy_ip:5060 -> phone_ip:49173  100 Trying

But the phone is not listening on 49173, so it will never see the reply.

This patch modifies nf_*_sip to work around this quirk by extracting
the SIP response port from the Via: header, iff the source IP in the
packet header matches the source IP in the SIP request.

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Patrick McHardy <kaber@trash.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

Showing 3 changed files with 44 additions and 3 deletions Side-by-side Diff

include/linux/netfilter/nf_conntrack_sip.h
Diff comments   View file @ 7266507
... ... @@ -4,12 +4,15 @@
4 4  
5 5 #include <net/netfilter/nf_conntrack_expect.h>
6 6  
  7 +#include <linux/types.h>
  8 +
7 9 #define SIP_PORT 5060
8 10 #define SIP_TIMEOUT 3600
9 11  
10 12 struct nf_ct_sip_master {
11 13 unsigned int register_cseq;
12 14 unsigned int invite_cseq;
  15 + __be16 forced_dport;
13 16 };
14 17  
15 18 enum sip_expectation_classes {
net/netfilter/nf_conntrack_sip.c
Diff comments   View file @ 7266507
... ... @@ -1440,8 +1440,25 @@
1440 1440 {
1441 1441 enum ip_conntrack_info ctinfo;
1442 1442 struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
  1443 + struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
  1444 + enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
1443 1445 unsigned int matchoff, matchlen;
1444 1446 unsigned int cseq, i;
  1447 + union nf_inet_addr addr;
  1448 + __be16 port;
  1449 +
  1450 + /* Many Cisco IP phones use a high source port for SIP requests, but
  1451 + * listen for the response on port 5060. If we are the local
  1452 + * router for one of these phones, save the port number from the
  1453 + * Via: header so that nf_nat_sip can redirect the responses to
  1454 + * the correct port.
  1455 + */
  1456 + if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen,
  1457 + SIP_HDR_VIA_UDP, NULL, &matchoff,
  1458 + &matchlen, &addr, &port) > 0 &&
  1459 + port != ct->tuplehash[dir].tuple.src.u.udp.port &&
  1460 + nf_inet_addr_cmp(&addr, &ct->tuplehash[dir].tuple.src.u3))
  1461 + ct_sip_info->forced_dport = port;
1445 1462  
1446 1463 for (i = 0; i < ARRAY_SIZE(sip_handlers); i++) {
1447 1464 const struct sip_handler *handler;
net/netfilter/nf_nat_sip.c
Diff comments   View file @ 7266507
... ... @@ -95,6 +95,7 @@
95 95 enum ip_conntrack_info ctinfo;
96 96 struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
97 97 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
  98 + struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
98 99 char buffer[INET6_ADDRSTRLEN + sizeof("[]:nnnnn")];
99 100 unsigned int buflen;
100 101 union nf_inet_addr newaddr;
... ... @@ -107,7 +108,8 @@
107 108 } else if (nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3, addr) &&
108 109 ct->tuplehash[dir].tuple.dst.u.udp.port == port) {
109 110 newaddr = ct->tuplehash[!dir].tuple.src.u3;
110   - newport = ct->tuplehash[!dir].tuple.src.u.udp.port;
  111 + newport = ct_sip_info->forced_dport ? :
  112 + ct->tuplehash[!dir].tuple.src.u.udp.port;
111 113 } else
112 114 return 1;
113 115  
... ... @@ -144,6 +146,7 @@
144 146 enum ip_conntrack_info ctinfo;
145 147 struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
146 148 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
  149 + struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
147 150 unsigned int coff, matchoff, matchlen;
148 151 enum sip_header_types hdr;
149 152 union nf_inet_addr addr;
... ... @@ -258,6 +261,21 @@
258 261 !map_sip_addr(skb, protoff, dataoff, dptr, datalen, SIP_HDR_TO))
259 262 return NF_DROP;
260 263  
  264 + /* Mangle destination port for Cisco phones, then fix up checksums */
  265 + if (dir == IP_CT_DIR_REPLY && ct_sip_info->forced_dport) {
  266 + struct udphdr *uh;
  267 +
  268 + if (!skb_make_writable(skb, skb->len))
  269 + return NF_DROP;
  270 +
  271 + uh = (void *)skb->data + protoff;
  272 + uh->dest = ct_sip_info->forced_dport;
  273 +
  274 + if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo, protoff,
  275 + 0, 0, NULL, 0))
  276 + return NF_DROP;
  277 + }
  278 +
261 279 return NF_ACCEPT;
262 280 }
263 281  
264 282  
... ... @@ -311,8 +329,10 @@
311 329 enum ip_conntrack_info ctinfo;
312 330 struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
313 331 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
  332 + struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
314 333 union nf_inet_addr newaddr;
315 334 u_int16_t port;
  335 + __be16 srcport;
316 336 char buffer[INET6_ADDRSTRLEN + sizeof("[]:nnnnn")];
317 337 unsigned int buflen;
318 338  
... ... @@ -326,8 +346,9 @@
326 346 /* If the signalling port matches the connection's source port in the
327 347 * original direction, try to use the destination port in the opposite
328 348 * direction. */
329   - if (exp->tuple.dst.u.udp.port ==
330   - ct->tuplehash[dir].tuple.src.u.udp.port)
  349 + srcport = ct_sip_info->forced_dport ? :
  350 + ct->tuplehash[dir].tuple.src.u.udp.port;
  351 + if (exp->tuple.dst.u.udp.port == srcport)
331 352 port = ntohs(ct->tuplehash[!dir].tuple.dst.u.udp.port);
332 353 else
333 354 port = ntohs(exp->tuple.dst.u.udp.port);