netfilter 43/62: nf_conntrack_sip: add TCP support

Patrick McHardy
2010-02-16T14:56:18Z

commit f5b321bd37fbec9188feb1f721ab46a5ac0b35da
Author: Patrick McHardy <kaber@trash.net>
Date: Thu Feb 11 12:26:19 2010 +0100

netfilter: nf_conntrack_sip: add TCP support

Add TCP support, which is mandated by RFC3261 for all SIP elements.

SIP over TCP is similar to UDP, except that messages are delimited
by Content-Length: headers and multiple messages may appear in one
packet.

Signed-off-by: Patrick McHardy <kaber@trash.net>

diff --git a/include/linux/netfilter/nf_conntrack_sip.h b/include/linux/netfilter/nf_conntrack_sip.h
index 2c6950b..fa9bb89 100644
--- a/include/linux/netfilter/nf_conntrack_sip.h
+++ b/include/linux/netfilter/nf_conntrack_sip.h
@@ -84,7 +84,8 @@ enum sip_header_types {
SIP_HDR_FROM,
SIP_HDR_TO,
SIP_HDR_CONTACT,
- SIP_HDR_VIA,
+ SIP_HDR_VIA_UDP,
+ SIP_HDR_VIA_TCP,
SIP_HDR_EXPIRES,
SIP_HDR_CONTENT_LENGTH,
};
diff --git a/net/ipv4/netfilter/nf_nat_sip.c b/net/ipv4/netfilter/nf_nat_sip.c
index 2454ea5..b232e40 100644
--- a/net/ipv4/netfilter/nf_nat_sip.c
+++ b/net/ipv4/netfilter/nf_nat_sip.c
@@ -122,7 +122,7 @@ static unsigned int ip_nat_sip(struct sk_buff *skb, unsigned int dataoff,

/* Translate topmost Via header and parameters */
if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen,
- SIP_HDR_VIA, NULL, &matchoff, &matchlen,
+ SIP_HDR_VIA_UDP, NULL, &matchoff, &matchlen,
&addr, &port) > 0) {
unsigned int matchend, poff, plen, buflen, n;
char buffer[sizeof("nnn.nnn.nnn.nnn:nnnnn")];
diff --git a/net/netfilter/nf_conntrack_sip.c b/net/netfilter/nf_conntrack_sip.c
index 0ec37d6..1cc75c5 100644
--- a/net/netfilter/nf_conntrack_sip.c
+++ b/net/netfilter/nf_conntrack_sip.c
@@ -16,6 +16,7 @@
#include <linux/inet.h>
#include <linux/in.h>
#include <linux/udp.h>
+#include <linux/tcp.h>
#include <linux/netfilter.h>

#include <net/netfilter/nf_conntrack.h>
@@ -287,7 +288,8 @@ static const struct sip_header ct_sip_hdrs[] = {
[SIP_HDR_FROM] = SIP_HDR("From", "f", "sip:", skp_epaddr_len),
[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_VIA_UDP] = SIP_HDR("Via", "v", "UDP ", epaddr_len),
+ [SIP_HDR_VIA_TCP] = SIP_HDR("Via", "v", "TCP ", epaddr_len),
[SIP_HDR_EXPIRES] = SIP_HDR("Expires", NULL, NULL, digits_len),
[SIP_HDR_CONTENT_LENGTH] = SIP_HDR("Content-Length", "l", NULL, digits_len),
};
@@ -519,6 +521,33 @@ int ct_sip_parse_header_uri(const struct nf_conn *ct, const char *dptr,
}
EXPORT_SYMBOL_GPL(ct_sip_parse_header_uri);

+static int ct_sip_parse_param(const struct nf_conn *ct, const char *dptr,
+ unsigned int dataoff, unsigned int datalen,
+ const char *name,
+ unsigned int *matchoff, unsigned int *matchlen)
+{
+ const char *limit = dptr + datalen;
+ const char *start;
+ const char *end;
+
+ limit = ct_sip_header_search(dptr + dataoff, limit, ",", strlen(","));
+ if (!limit)
+ limit = dptr + datalen;
+
+ start = ct_sip_header_search(dptr + dataoff, limit, name, strlen(name));
+ if (!start)
+ return 0;
+ start += strlen(name);
+
+ end = ct_sip_header_search(start, limit, ";", strlen(";"));
+ if (!end)
+ end = limit;
+
+ *matchoff = start - dptr;
+ *matchlen = end - start;
+ return 1;
+}
+
/* Parse address from header parameter and return address, offset and length */
int ct_sip_parse_address_param(const struct nf_conn *ct, const char *dptr,
unsigned int dataoff, unsigned int datalen,
@@ -577,6 +606,29 @@ int ct_sip_parse_numerical_param(const struct nf_conn *ct, const char *dptr,
}
EXPORT_SYMBOL_GPL(ct_sip_parse_numerical_param);

+static int ct_sip_parse_transport(struct nf_conn *ct, const char *dptr,
+ unsigned int dataoff, unsigned int datalen,
+ u8 *proto)
+{
+ unsigned int matchoff, matchlen;
+
+ if (ct_sip_parse_param(ct, dptr, dataoff, datalen, "transport=",
+ &matchoff, &matchlen)) {
+ if (!strnicmp(dptr + matchoff, "TCP", strlen("TCP")))
+ *proto = IPPROTO_TCP;
+ else if (!strnicmp(dptr + matchoff, "UDP", strlen("UDP")))
+ *proto = IPPROTO_UDP;
+ else
+ return 0;
+
+ if (*proto != nf_ct_protonum(ct))
+ return 0;
+ } else
+ *proto = nf_ct_protonum(ct);
+
+ return 1;
+}
+
/* SDP header parsing: a SDP session description contains an ordered set of
* headers, starting with a section containing general session parameters,
* optionally followed by multiple media descriptions.
@@ -685,7 +737,7 @@ static int ct_sip_parse_sdp_addr(const struct nf_conn *ct, const char *dptr,

static int refresh_signalling_expectation(struct nf_conn *ct,
union nf_inet_addr *addr,
- __be16 port,
+ u8 proto, __be16 port,
unsigned int expires)
{
struct nf_conn_help *help = nfct_help(ct);
@@ -697,6 +749,7 @@ static int refresh_signalling_expectation(struct nf_conn *ct,
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.protonum != proto ||
exp->tuple.dst.u.udp.port != port)
continue;
if (!del_timer(&exp->timeout))
@@ -1048,6 +1101,7 @@ static int process_register_request(struct sk_buff *skb, unsigned int dataoff,
struct nf_conntrack_expect *exp;
union nf_inet_addr *saddr, daddr;
__be16 port;
+ u8 proto;
unsigned int expires = 0;
int ret;
typeof(nf_nat_sip_expect_hook) nf_nat_sip_expect;
@@ -1080,6 +1134,10 @@ static int process_register_request(struct sk_buff *skb, unsigned int dataoff,
if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3, &daddr))
return NF_ACCEPT;

+ if (ct_sip_parse_transport(ct, *dptr, matchoff + matchlen, *datalen,
+ &proto) == 0)
+ return NF_ACCEPT;
+
if (ct_sip_parse_numerical_param(ct, *dptr,
matchoff + matchlen, *datalen,
"expires=", NULL, NULL, &expires) < 0)
@@ -1099,7 +1157,7 @@ static int process_register_request(struct sk_buff *skb, unsigned int dataoff,
saddr = &ct->tuplehash[!dir].tuple.src.u3;

nf_ct_expect_init(exp, SIP_EXPECT_SIGNALLING, nf_ct_l3num(ct),
- saddr, &daddr, IPPROTO_UDP, NULL, &port);
+ saddr, &daddr, proto, NULL, &port);
exp->timeout.expires = sip_timeout * HZ;
exp->helper = nfct_help(ct)->helper;
exp->flags = NF_CT_EXPECT_PERMANENT | NF_CT_EXPECT_INACTIVE;
@@ -1132,6 +1190,7 @@ static int process_register_response(struct sk_buff *skb, unsigned int dataoff,
enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
union nf_inet_addr addr;
__be16 port;
+ u8 proto;
unsigned int matchoff, matchlen, coff = 0;
unsigned int expires = 0;
int in_contact = 0, ret;
@@ -1172,6 +1231,10 @@ static int process_register_response(struct sk_buff *skb, unsigned int dataoff,
if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3, &addr))
continue;

+ if (ct_sip_parse_transport(ct, *dptr, matchoff + matchlen,
+ *datalen, &proto) == 0)
+ continue;
+
ret = ct_sip_parse_numerical_param(ct, *dptr,
matchoff + matchlen,
*datalen, "expires=",
@@ -1180,7 +1243,8 @@ static int process_register_response(struct sk_buff *skb, unsigned int dataoff,
return NF_DROP;
if (c_expires == 0)
break;
- if (refresh_signalling_expectation(ct, &addr, port, c_expires))
+ if (refresh_signalling_expectation(ct, &addr, proto, port,
+ c_expires))
return NF_ACCEPT;
}

@@ -1265,50 +1329,123 @@ static int process_sip_request(struct sk_buff *skb, unsigned int dataoff,
return NF_ACCEPT;
}

-static int sip_help(struct sk_buff *skb,
- unsigned int protoff,
- struct nf_conn *ct,
- enum ip_conntrack_info ctinfo)
+static int process_sip_msg(struct sk_buff *skb, struct nf_conn *ct,
+ unsigned int dataoff, const char **dptr,
+ unsigned int *datalen)
+{
+ typeof(nf_nat_sip_hook) nf_nat_sip;
+ int ret;
+
+ if (strnicmp(*dptr, "SIP/2.0 ", strlen("SIP/2.0 ")) != 0)
+ ret = process_sip_request(skb, dataoff, dptr, datalen);
+ else
+ ret = process_sip_response(skb, dataoff, dptr, datalen);
+
+ if (ret == NF_ACCEPT && ct->status & IPS_NAT_MASK) {
+ nf_nat_sip = rcu_dereference(nf_nat_sip_hook);
+ if (nf_nat_sip && !nf_nat_sip(skb, dataoff, dptr, datalen))
+ ret = NF_DROP;
+ }
+
+ return ret;
+}
+
+static int sip_help_tcp(struct sk_buff *skb, unsigned int protoff,
+ struct nf_conn *ct, enum ip_conntrack_info ctinfo)
{
+ struct tcphdr *th, _tcph;
unsigned int dataoff, datalen;
- const char *dptr;
+ unsigned int matchoff, matchlen, clen;
+ unsigned int msglen, origlen;
+ const char *dptr, *end;
+ s16 diff, tdiff = 0;
int ret;
- typeof(nf_nat_sip_hook) nf_nat_sip;
+
+ if (ctinfo != IP_CT_ESTABLISHED &&
+ ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY)
+ return NF_ACCEPT;

/* No Data ? */
- dataoff = protoff + sizeof(struct udphdr);
+ th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
+ if (th == NULL)
+ return NF_ACCEPT;
+ dataoff = protoff + th->doff * 4;
if (dataoff >= skb->len)
return NF_ACCEPT;

nf_ct_refresh(ct, skb, sip_timeout * HZ);

- if (!skb_is_nonlinear(skb))
- dptr = skb->data + dataoff;
- else {
+ if (skb_is_nonlinear(skb)) {
pr_debug("Copy of skbuff not supported yet.\n");
return NF_ACCEPT;
}

+ dptr = skb->data + dataoff;
datalen = skb->len - dataoff;
if (datalen < strlen("SIP/2.0 200"))
return NF_ACCEPT;

- if (strnicmp(dptr, "SIP/2.0 ", strlen("SIP/2.0 ")) != 0)
- ret = process_sip_request(skb, dataoff, &dptr, &datalen);
- else
- ret = process_sip_response(skb, dataoff, &dptr, &datalen);
+ while (1) {
+ if (ct_sip_get_header(ct, dptr, 0, datalen,
+ SIP_HDR_CONTENT_LENGTH,
+ &matchoff, &matchlen) <= 0)
+ break;

- if (ret == NF_ACCEPT && ct->status & IPS_NAT_MASK) {
- nf_nat_sip = rcu_dereference(nf_nat_sip_hook);
- if (nf_nat_sip && !nf_nat_sip(skb, dataoff, &dptr, &datalen))
- ret = NF_DROP;
+ clen = simple_strtoul(dptr + matchoff, (char **)&end, 10);
+ if (dptr + matchoff == end)
+ break;
+
+ if (end + strlen("\r\n\r\n") > dptr + datalen)
+ break;
+ if (end[0] != '\r' || end[1] != '\n' ||
+ end[2] != '\r' || end[3] != '\n')
+ break;
+ end += strlen("\r\n\r\n") + clen;
+
+ msglen = origlen = end - dptr;
+
+ ret = process_sip_msg(skb, ct, dataoff, &dptr, &msglen);
+ if (ret != NF_ACCEPT)
+ break;
+ diff = msglen - origlen;
+ tdiff += diff;
+
+ dataoff += msglen;
+ dptr += msglen;
+ datalen = datalen + diff - msglen;
}

return ret;
}

-static struct nf_conntrack_helper sip[MAX_PORTS][2] __read_mostly;
-static char sip_names[MAX_PORTS][2][sizeof("sip-65535")] __read_mostly;
+static int sip_help_udp(struct sk_buff *skb, unsigned int protoff,
+ struct nf_conn *ct, enum ip_conntrack_info ctinfo)
+{
+ unsigned int dataoff, datalen;
+ const char *dptr;
+
+ /* No Data ? */
+ dataoff = protoff + sizeof(struct udphdr);
+ if (dataoff >= skb->len)
+ return NF_ACCEPT;
+
+ nf_ct_refresh(ct, skb, sip_timeout * HZ);
+
+ if (skb_is_nonlinear(skb)) {
+ pr_debug("Copy of skbuff not supported yet.\n");
+ return NF_ACCEPT;
+ }
+
+ dptr = skb->data + dataoff;
+ datalen = skb->len - dataoff;
+ if (datalen < strlen("SIP/2.0 200"))
+ return NF_ACCEPT;
+
+ return process_sip_msg(skb, ct, dataoff, &dptr, &datalen);
+}
+
+static struct nf_conntrack_helper sip[MAX_PORTS][4] __read_mostly;
+static char sip_names[MAX_PORTS][4][sizeof("sip-65535")] __read_mostly;

static const struct nf_conntrack_expect_policy sip_exp_policy[SIP_EXPECT_MAX + 1] = {
[SIP_EXPECT_SIGNALLING] = {
@@ -1333,7 +1470,7 @@ static void nf_conntrack_sip_fini(void)
int i, j;

for (i = 0; i < ports_c; i++) {
- for (j = 0; j < 2; j++) {
+ for (j = 0; j < ARRAY_SIZE(sip[i]); j++) {
if (sip[i][j].me == NULL)
continue;
nf_conntrack_helper_unregister(&sip[i][j]);
@@ -1353,14 +1490,24 @@ static int __init nf_conntrack_sip_init(void)
memset(&sip[i], 0, sizeof(sip[i]));

sip[i][0].tuple.src.l3num = AF_INET;
- sip[i][1].tuple.src.l3num = AF_INET6;
- for (j = 0; j < 2; j++) {
- sip[i][j].tuple.dst.protonum = IPPROTO_UDP;
+ sip[i][0].tuple.dst.protonum = IPPROTO_UDP;
+ sip[i][0].help = sip_help_udp;
+ sip[i][1].tuple.src.l3num = AF_INET;
+ sip[i][1].tuple.dst.protonum = IPPROTO_TCP;
+ sip[i][1].help = sip_help_tcp;
+
+ sip[i][2].tuple.src.l3num = AF_INET6;
+ sip[i][2].tuple.dst.protonum = IPPROTO_UDP;
+ sip[i][2].help = sip_help_udp;
+ sip[i][3].tuple.src.l3num = AF_INET6;
+ sip[i][3].tuple.dst.protonum = IPPROTO_TCP;
+ sip[i][3].help = sip_help_tcp;
+
+ for (j = 0; j < ARRAY_SIZE(sip[i]); j++) {
sip[i][j].tuple.src.u.udp.port = htons(ports[i]);
sip[i][j].expect_policy = sip_exp_policy;
sip[i][j].expect_class_max = SIP_EXPECT_MAX;
sip[i][j].me = THIS_MODULE;
- sip[i][j].help = sip_help;

tmpname = &sip_names[i][j][0];
if (ports[i] == SIP_PORT)