[NETFILTER]: nf_conntrack_sip: create signalling expectations
Create expectations for incoming signalling connections when seeing
a REGISTER request. This is needed when the registrar uses a
different source port number for signalling messages and for receiving
incoming calls from other endpoints than the registrar.
Signed-off-by: Patrick McHardy <kaber@xxxxxxxxx>
---
commit 7446ec09d8df7385419cdd3008c4261c2fec7474
tree df72215c8cd97fd48e91d2cc80bc0378105e8ccd
parent 7d30e9292bdf36be9ec46fa04441fc8e94055963
author Patrick McHardy <kaber@xxxxxxxxx> Thu, 28 Feb 2008 12:08:33 +0100
committer Patrick McHardy <kaber@xxxxxxxxx> Thu, 28 Feb 2008 12:08:33 +0100
include/linux/netfilter/nf_conntrack_sip.h | 14 ++
include/net/netfilter/nf_conntrack.h | 4
net/ipv4/netfilter/nf_nat_sip.c | 111 +++++++++++---
net/netfilter/nf_conntrack_sip.c | 225 +++++++++++++++++++++++++++-
4 files changed, 322 insertions(+), 32 deletions(-)
diff --git a/include/linux/netfilter/nf_conntrack_sip.h b/include/linux/netfilter/nf_conntrack_sip.h
index 96e0caa..7cc84ed 100644
--- a/include/linux/netfilter/nf_conntrack_sip.h
+++ b/include/linux/netfilter/nf_conntrack_sip.h
@@ -5,8 +5,13 @@
#define SIP_PORT 5060
#define SIP_TIMEOUT 3600
+struct nf_ct_sip_master {
+ unsigned int register_cseq;
+};
+
enum sip_expectation_classes {
- SIP_EXPECT,
+ SIP_EXPECT_SIGNALLING,
+ SIP_EXPECT_AUDIO,
__SIP_EXPECT_MAX
};
#define SIP_EXPECT_MAX (__SIP_EXPECT_MAX - 1)
@@ -65,6 +70,7 @@ enum sip_header_types {
SIP_HDR_TO,
SIP_HDR_CONTACT,
SIP_HDR_VIA,
+ SIP_HDR_EXPIRES,
SIP_HDR_CONTENT_LENGTH,
};
@@ -81,6 +87,12 @@ enum sdp_header_types {
extern unsigned int (*nf_nat_sip_hook)(struct sk_buff *skb,
const char **dptr,
unsigned int *datalen);
+extern unsigned int (*nf_nat_sip_expect_hook)(struct sk_buff *skb,
+ const char **dptr,
+ unsigned int *datalen,
+ struct nf_conntrack_expect *exp,
+ unsigned int matchoff,
+ unsigned int matchlen);
extern unsigned int (*nf_nat_sdp_hook)(struct sk_buff *skb,
const char **dptr,
unsigned int *datalen,
diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h
index 9228771..4a4f870 100644
--- a/include/net/netfilter/nf_conntrack.h
+++ b/include/net/netfilter/nf_conntrack.h
@@ -46,6 +46,7 @@ union nf_conntrack_expect_proto {
#include <linux/netfilter/nf_conntrack_pptp.h>
#include <linux/netfilter/nf_conntrack_h323.h>
#include <linux/netfilter/nf_conntrack_sane.h>
+#include <linux/netfilter/nf_conntrack_sip.h>
/* per conntrack: application helper private data */
union nf_conntrack_help {
@@ -54,6 +55,7 @@ union nf_conntrack_help {
struct nf_ct_pptp_master ct_pptp_info;
struct nf_ct_h323_master ct_h323_info;
struct nf_ct_sane_master ct_sane_info;
+ struct nf_ct_sip_master ct_sip_info;
};
#include <linux/types.h>
@@ -76,7 +78,7 @@ do { \
struct nf_conntrack_helper;
/* Must be kept in sync with the classes defined by helpers */
-#define NF_CT_MAX_EXPECT_CLASSES 1
+#define NF_CT_MAX_EXPECT_CLASSES 2
/* nf_conn feature for connections that have a helper */
struct nf_conn_help {
diff --git a/net/ipv4/netfilter/nf_nat_sip.c b/net/ipv4/netfilter/nf_nat_sip.c
index b443618..4b85e21 100644
--- a/net/ipv4/netfilter/nf_nat_sip.c
+++ b/net/ipv4/netfilter/nf_nat_sip.c
@@ -205,6 +205,91 @@ next:
return NF_ACCEPT;
}
+/* Handles expected signalling connections and media streams */
+static void ip_nat_sip_expected(struct nf_conn *ct,
+ struct nf_conntrack_expect *exp)
+{
+ struct nf_nat_range 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 = (IP_NAT_RANGE_MAP_IPS | IP_NAT_RANGE_PROTO_SPECIFIED);
+ range.min = range.max = exp->saved_proto;
+ range.min_ip = range.max_ip = exp->saved_ip;
+ nf_nat_setup_info(ct, &range, IP_NAT_MANIP_DST);
+
+ /* Change src to where master sends to, but only if the connection
+ * actually came from the same source. */
+ if (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip ==
+ ct->master->tuplehash[exp->dir].tuple.src.u3.ip) {
+ range.flags = IP_NAT_RANGE_MAP_IPS;
+ range.min_ip = range.max_ip
+ = ct->master->tuplehash[!exp->dir].tuple.dst.u3.ip;
+ nf_nat_setup_info(ct, &range, IP_NAT_MANIP_SRC);
+ }
+}
+
+static unsigned int ip_nat_sip_expect(struct sk_buff *skb,
+ 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);
+ __be32 newip;
+ u_int16_t port;
+ char buffer[sizeof("nnn.nnn.nnn.nnn:nnnnn")];
+ unsigned buflen;
+
+ /* Connection will come from reply */
+ if (ct->tuplehash[dir].tuple.src.u3.ip == ct->tuplehash[!dir].tuple.dst.u3.ip)
+ newip = exp->tuple.dst.u3.ip;
+ else
+ newip = ct->tuplehash[!dir].tuple.dst.u3.ip;
+
+ /* If the signalling port matches the connection's source port in the
+ * original direction, try to use the destination port in the opposite
+ * direction. */
+ if (exp->tuple.dst.u.udp.port ==
+ ct->tuplehash[dir].tuple.src.u.udp.port)
+ port = ntohs(ct->tuplehash[!dir].tuple.dst.u.udp.port);
+ else
+ port = ntohs(exp->tuple.dst.u.udp.port);
+
+ exp->saved_ip = exp->tuple.dst.u3.ip;
+ exp->tuple.dst.u3.ip = newip;
+ exp->saved_proto.udp.port = exp->tuple.dst.u.udp.port;
+ exp->dir = !dir;
+ exp->expectfn = ip_nat_sip_expected;
+
+ for (; port != 0; port++) {
+ exp->tuple.dst.u.udp.port = htons(port);
+ if (nf_ct_expect_related(exp) == 0)
+ break;
+ }
+
+ if (port == 0)
+ return NF_DROP;
+
+ if (exp->tuple.dst.u3.ip != exp->saved_ip ||
+ exp->tuple.dst.u.udp.port != exp->saved_proto.udp.port) {
+ buflen = sprintf(buffer, "%u.%u.%u.%u:%u",
+ NIPQUAD(newip), port);
+ if (!mangle_packet(skb, dptr, datalen, matchoff, matchlen,
+ buffer, buflen))
+ goto err;
+ }
+ return NF_ACCEPT;
+
+err:
+ nf_ct_unexpect_related(exp);
+ return NF_DROP;
+}
+
static int mangle_content_len(struct sk_buff *skb,
const char **dptr, unsigned int *datalen)
{
@@ -275,27 +360,6 @@ static unsigned int mangle_sdp(struct sk_buff *skb,
return mangle_content_len(skb, dptr, datalen);
}
-static void ip_nat_sdp_expect(struct nf_conn *ct,
- struct nf_conntrack_expect *exp)
-{
- struct nf_nat_range 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 = (IP_NAT_RANGE_MAP_IPS | IP_NAT_RANGE_PROTO_SPECIFIED);
- range.min = range.max = exp->saved_proto;
- range.min_ip = range.max_ip = exp->saved_ip;
- nf_nat_setup_info(ct, &range, IP_NAT_MANIP_DST);
-
- /* Change src to where master sends to */
- range.flags = IP_NAT_RANGE_MAP_IPS;
- range.min_ip = range.max_ip
- = ct->master->tuplehash[!exp->dir].tuple.dst.u3.ip;
- nf_nat_setup_info(ct, &range, IP_NAT_MANIP_SRC);
-}
-
/* 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 *skb,
@@ -322,7 +386,7 @@ static unsigned int ip_nat_sdp(struct sk_buff *skb,
/* When you see the packet, we need to NAT it the same as the
this one. */
- exp->expectfn = ip_nat_sdp_expect;
+ exp->expectfn = ip_nat_sip_expected;
/* Try to get same port: if not, try to change it. */
for (port = ntohs(exp->saved_proto.udp.port); port != 0; port++) {
@@ -344,6 +408,7 @@ static unsigned int ip_nat_sdp(struct sk_buff *skb,
static void __exit nf_nat_sip_fini(void)
{
rcu_assign_pointer(nf_nat_sip_hook, NULL);
+ rcu_assign_pointer(nf_nat_sip_expect_hook, NULL);
rcu_assign_pointer(nf_nat_sdp_hook, NULL);
synchronize_rcu();
}
@@ -351,8 +416,10 @@ static void __exit nf_nat_sip_fini(void)
static int __init nf_nat_sip_init(void)
{
BUG_ON(nf_nat_sip_hook != NULL);
+ BUG_ON(nf_nat_sip_expect_hook != NULL);
BUG_ON(nf_nat_sdp_hook != NULL);
rcu_assign_pointer(nf_nat_sip_hook, ip_nat_sip);
+ rcu_assign_pointer(nf_nat_sip_expect_hook, ip_nat_sip_expect);
rcu_assign_pointer(nf_nat_sdp_hook, ip_nat_sdp);
return 0;
}
diff --git a/net/netfilter/nf_conntrack_sip.c b/net/netfilter/nf_conntrack_sip.c
index bedaf2e..2f21d0c 100644
--- a/net/netfilter/nf_conntrack_sip.c
+++ b/net/netfilter/nf_conntrack_sip.c
@@ -37,11 +37,24 @@ static unsigned int sip_timeout __read_mostly = SIP_TIMEOUT;
module_param(sip_timeout, uint, 0600);
MODULE_PARM_DESC(sip_timeout, "timeout for the master SIP session");
+static int sip_direct_signalling __read_mostly = 1;
+module_param(sip_direct_signalling, int, 0600);
+MODULE_PARM_DESC(sip_direct_signalling, "expect incoming calls from registrar "
+ "only (default 1)");
+
unsigned int (*nf_nat_sip_hook)(struct sk_buff *skb,
const char **dptr,
unsigned int *datalen) __read_mostly;
EXPORT_SYMBOL_GPL(nf_nat_sip_hook);
+unsigned int (*nf_nat_sip_expect_hook)(struct sk_buff *skb,
+ const char **dptr,
+ unsigned int *datalen,
+ struct nf_conntrack_expect *exp,
+ unsigned int matchoff,
+ unsigned int matchlen) __read_mostly;
+EXPORT_SYMBOL_GPL(nf_nat_sip_expect_hook);
+
unsigned int (*nf_nat_sdp_hook)(struct sk_buff *skb,
const char **dptr,
unsigned int *datalen,
@@ -227,6 +240,7 @@ static const struct sip_header ct_sip_hdrs[] = {
[SIP_HDR_TO] = SIP_HDR("To", "t", "sip:", skp_epaddr_len),
[SIP_HDR_CONTACT] = SIP_HDR("Contact", "m", "sip:", skp_epaddr_len),
[SIP_HDR_VIA] = SIP_HDR("Via", "v", "UDP ", epaddr_len),
+ [SIP_HDR_EXPIRES] = SIP_HDR("Expires", NULL, NULL, digits_len),
[SIP_HDR_CONTENT_LENGTH] = SIP_HDR("Content-Length", "l", NULL, digits_len),
};
@@ -601,7 +615,35 @@ int ct_sip_get_sdp_header(const struct nf_conn *ct, const char *dptr,
}
EXPORT_SYMBOL_GPL(ct_sip_get_sdp_header);
-static void flush_expectations(struct nf_conn *ct)
+static int refresh_signalling_expectation(struct nf_conn *ct,
+ union nf_inet_addr *addr,
+ __be16 port,
+ unsigned int expires)
+{
+ struct nf_conn_help *help = nfct_help(ct);
+ struct nf_conntrack_expect *exp;
+ struct hlist_node *n, *next;
+ int found = 0;
+
+ spin_lock_bh(&nf_conntrack_lock);
+ hlist_for_each_entry_safe(exp, n, next, &help->expectations, lnode) {
+ if (exp->class != SIP_EXPECT_SIGNALLING ||
+ !nf_inet_addr_cmp(&exp->tuple.dst.u3, addr) ||
+ exp->tuple.dst.u.udp.port != port)
+ continue;
+ if (!del_timer(&exp->timeout))
+ continue;
+ exp->flags &= ~NF_CT_EXPECT_INACTIVE;
+ exp->timeout.expires = jiffies + expires * HZ;
+ add_timer(&exp->timeout);
+ found = 1;
+ break;
+ }
+ spin_unlock_bh(&nf_conntrack_lock);
+ return found;
+}
+
+static void flush_expectations(struct nf_conn *ct, int media)
{
struct nf_conn_help *help = nfct_help(ct);
struct nf_conntrack_expect *exp;
@@ -609,10 +651,14 @@ static void flush_expectations(struct nf_conn *ct)
spin_lock_bh(&nf_conntrack_lock);
hlist_for_each_entry_safe(exp, n, next, &help->expectations, lnode) {
+ if ((exp->class != SIP_EXPECT_SIGNALLING) ^ media)
+ continue;
if (!del_timer(&exp->timeout))
continue;
nf_ct_unlink_expect(exp);
nf_ct_expect_put(exp);
+ if (!media)
+ break;
}
spin_unlock_bh(&nf_conntrack_lock);
}
@@ -632,7 +678,7 @@ static int set_expected_rtp(struct sk_buff *skb,
exp = nf_ct_expect_alloc(ct);
if (exp == NULL)
return NF_DROP;
- nf_ct_expect_init(exp, SIP_EXPECT, family,
+ nf_ct_expect_init(exp, SIP_EXPECT_AUDIO, family,
&ct->tuplehash[!dir].tuple.src.u3, addr,
IPPROTO_UDP, NULL, &port);
@@ -697,7 +743,7 @@ static int process_invite_response(struct sk_buff *skb,
(code >= 200 && code <= 299))
return process_sdp(skb, dptr, datalen, cseq);
else {
- flush_expectations(ct);
+ flush_expectations(ct, 1);
return NF_ACCEPT;
}
}
@@ -713,7 +759,7 @@ static int process_update_response(struct sk_buff *skb,
(code >= 200 && code <= 299))
return process_sdp(skb, dptr, datalen, cseq);
else {
- flush_expectations(ct);
+ flush_expectations(ct, 1);
return NF_ACCEPT;
}
}
@@ -729,7 +775,7 @@ static int process_prack_response(struct sk_buff *skb,
(code >= 200 && code <= 299))
return process_sdp(skb, dptr, datalen, cseq);
else {
- flush_expectations(ct);
+ flush_expectations(ct, 1);
return NF_ACCEPT;
}
}
@@ -741,7 +787,165 @@ static int process_bye_request(struct sk_buff *skb,
enum ip_conntrack_info ctinfo;
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
- flush_expectations(ct);
+ flush_expectations(ct, 1);
+ return NF_ACCEPT;
+}
+
+/* Parse a REGISTER request and create a permanent expectation for incoming
+ * signalling connections. The expectation is marked inactive and is activated
+ * when receiving a response indicating success from the registrar.
+ */
+static int process_register_request(struct sk_buff *skb,
+ const char **dptr, unsigned int *datalen,
+ unsigned int cseq)
+{
+ enum ip_conntrack_info ctinfo;
+ struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
+ struct nf_conn_help *help = nfct_help(ct);
+ enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
+ int family = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num;
+ unsigned int matchoff, matchlen;
+ struct nf_conntrack_expect *exp;
+ union nf_inet_addr *saddr, daddr;
+ __be16 port;
+ unsigned int expires = 0;
+ int ret;
+ typeof(nf_nat_sip_expect_hook) nf_nat_sip_expect;
+
+ /* Expected connections can not register again. */
+ if (ct->status & IPS_EXPECTED)
+ return NF_ACCEPT;
+
+ /* We must check the expiration time: a value of zero signals the
+ * registrar to release the binding. We'll remove our expectation
+ * when receiving the new bindings in the response, but we don't
+ * want to create new ones.
+ *
+ * The expiration time may be contained in Expires: header, the
+ * Contact: header parameters or the URI parameters.
+ */
+ if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_EXPIRES,
+ &matchoff, &matchlen) > 0)
+ expires = simple_strtoul(*dptr + matchoff, NULL, 10);
+
+ ret = ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen,
+ SIP_HDR_CONTACT, NULL,
+ &matchoff, &matchlen, &daddr, &port);
+ if (ret < 0)
+ return NF_DROP;
+ else if (ret == 0)
+ return NF_ACCEPT;
+
+ /* We don't support third-party registrations */
+ if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3, &daddr))
+ return NF_ACCEPT;
+
+ if (ct_sip_parse_numerical_param(ct, *dptr,
+ matchoff + matchlen, *datalen,
+ "expires=", NULL, NULL, &expires) < 0)
+ return NF_DROP;
+
+ if (expires == 0) {
+ ret = NF_ACCEPT;
+ goto store_cseq;
+ }
+
+ exp = nf_ct_expect_alloc(ct);
+ if (!exp)
+ return NF_DROP;
+
+ saddr = NULL;
+ if (sip_direct_signalling)
+ saddr = &ct->tuplehash[!dir].tuple.src.u3;
+
+ nf_ct_expect_init(exp, SIP_EXPECT_SIGNALLING, family, saddr, &daddr,
+ IPPROTO_UDP, NULL, &port);
+ exp->timeout.expires = sip_timeout * HZ;
+ exp->helper = nfct_help(ct)->helper;
+ exp->flags = NF_CT_EXPECT_PERMANENT | NF_CT_EXPECT_INACTIVE;
+
+ nf_nat_sip_expect = rcu_dereference(nf_nat_sip_expect_hook);
+ if (nf_nat_sip_expect && ct->status & IPS_NAT_MASK)
+ ret = nf_nat_sip_expect(skb, dptr, datalen, exp,
+ matchoff, matchlen);
+ else {
+ if (nf_ct_expect_related(exp) != 0)
+ ret = NF_DROP;
+ else
+ ret = NF_ACCEPT;
+ }
+ nf_ct_expect_put(exp);
+
+store_cseq:
+ if (ret == NF_ACCEPT)
+ help->help.ct_sip_info.register_cseq = cseq;
+ return ret;
+}
+
+static int process_register_response(struct sk_buff *skb,
+ const char **dptr, unsigned int *datalen,
+ unsigned int cseq, unsigned int code)
+{
+ enum ip_conntrack_info ctinfo;
+ struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
+ struct nf_conn_help *help = nfct_help(ct);
+ enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
+ union nf_inet_addr addr;
+ __be16 port;
+ unsigned int matchoff, matchlen, dataoff = 0;
+ unsigned int expires = 0;
+ int in_contact = 0, ret;
+
+ /* According to RFC 3261, "UAs MUST NOT send a new registration until
+ * they have received a final response from the registrar for the
+ * previous one or the previous REGISTER request has timed out".
+ *
+ * However, some servers fail to detect retransmissions and send late
+ * responses, so we store the sequence number of the last valid
+ * request and compare it here.
+ */
+ if (help->help.ct_sip_info.register_cseq != cseq)
+ return NF_ACCEPT;
+
+ if (code >= 100 && code <= 199)
+ return NF_ACCEPT;
+ if (code < 200 || code > 299)
+ goto flush;
+
+ if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_EXPIRES,
+ &matchoff, &matchlen) > 0)
+ expires = simple_strtoul(*dptr + matchoff, NULL, 10);
+
+ while (1) {
+ unsigned int c_expires = expires;
+
+ ret = ct_sip_parse_header_uri(ct, *dptr, &dataoff, *datalen,
+ SIP_HDR_CONTACT, &in_contact,
+ &matchoff, &matchlen,
+ &addr, &port);
+ if (ret < 0)
+ return NF_DROP;
+ else if (ret == 0)
+ break;
+
+ /* We don't support third-party registrations */
+ if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3, &addr))
+ continue;
+
+ ret = ct_sip_parse_numerical_param(ct, *dptr,
+ matchoff + matchlen,
+ *datalen, "expires=",
+ NULL, NULL, &c_expires);
+ if (ret < 0)
+ return NF_DROP;
+ if (c_expires == 0)
+ break;
+ if (refresh_signalling_expectation(ct, &addr, port, c_expires))
+ return NF_ACCEPT;
+ }
+
+flush:
+ flush_expectations(ct, 0);
return NF_ACCEPT;
}
@@ -751,6 +955,7 @@ static const struct sip_handler sip_handlers[] = {
SIP_HANDLER("ACK", process_sdp, NULL),
SIP_HANDLER("PRACK", process_sdp, process_prack_response),
SIP_HANDLER("BYE", process_bye_request, NULL),
+ SIP_HANDLER("REGISTER", process_register_request, process_register_response),
};
static int process_sip_response(struct sk_buff *skb,
@@ -863,8 +1068,12 @@ static struct nf_conntrack_helper sip[MAX_PORTS][2] __read_mostly;
static char sip_names[MAX_PORTS][2][sizeof("sip-65535")] __read_mostly;
static const struct nf_conntrack_expect_policy sip_exp_policy[SIP_EXPECT_MAX + 1] = {
- [SIP_EXPECT] = {
- .max_expected = 2,
+ [SIP_EXPECT_SIGNALLING] = {
+ .max_expected = 1,
+ .timeout = 3 * 60,
+ },
+ [SIP_EXPECT_AUDIO] = {
+ .max_expected = IP_CT_DIR_MAX,
.timeout = 3 * 60,
},
};
-
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