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[NETFILTER]: nf_conntrack_sip: create RTCP expectations
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Create expectations for the RTCP connections in addition to RTP connections.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Patrick McHardy authored and David S. Miller committed Mar 26, 2008
1 parent d901a93 commit a9c1d35
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Showing 3 changed files with 66 additions and 37 deletions.
3 changes: 2 additions & 1 deletion include/linux/netfilter/nf_conntrack_sip.h
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Original file line number Diff line number Diff line change
Expand Up @@ -96,7 +96,8 @@ extern unsigned int (*nf_nat_sip_expect_hook)(struct sk_buff *skb,
extern unsigned int (*nf_nat_sdp_hook)(struct sk_buff *skb,
const char **dptr,
unsigned int *datalen,
struct nf_conntrack_expect *exp);
struct nf_conntrack_expect *rtp_exp,
struct nf_conntrack_expect *rtcp_exp);

extern int ct_sip_parse_request(const struct nf_conn *ct,
const char *dptr, unsigned int datalen,
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42 changes: 26 additions & 16 deletions net/ipv4/netfilter/nf_nat_sip.c
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Original file line number Diff line number Diff line change
Expand Up @@ -364,7 +364,8 @@ static unsigned int mangle_sdp(struct sk_buff *skb,
Mangle it, and change the expectation to match the new version. */
static unsigned int ip_nat_sdp(struct sk_buff *skb,
const char **dptr, unsigned int *datalen,
struct nf_conntrack_expect *exp)
struct nf_conntrack_expect *rtp_exp,
struct nf_conntrack_expect *rtcp_exp)
{
enum ip_conntrack_info ctinfo;
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
Expand All @@ -375,31 +376,40 @@ static unsigned int ip_nat_sdp(struct sk_buff *skb,
/* 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;
newip = rtp_exp->tuple.dst.u3.ip;
else
newip = ct->tuplehash[!dir].tuple.dst.u3.ip;

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;

/* When you see the packet, we need to NAT it the same as the
this one. */
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++) {
exp->tuple.dst.u.udp.port = htons(port);
if (nf_ct_expect_related(exp) == 0)
rtp_exp->saved_ip = rtp_exp->tuple.dst.u3.ip;
rtp_exp->tuple.dst.u3.ip = newip;
rtp_exp->saved_proto.udp.port = rtp_exp->tuple.dst.u.udp.port;
rtp_exp->dir = !dir;
rtp_exp->expectfn = ip_nat_sip_expected;

rtcp_exp->saved_ip = rtcp_exp->tuple.dst.u3.ip;
rtcp_exp->tuple.dst.u3.ip = newip;
rtcp_exp->saved_proto.udp.port = rtcp_exp->tuple.dst.u.udp.port;
rtcp_exp->dir = !dir;
rtcp_exp->expectfn = ip_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) {
rtp_exp->tuple.dst.u.udp.port = htons(port);
if (nf_ct_expect_related(rtp_exp) != 0)
continue;
rtcp_exp->tuple.dst.u.udp.port = htons(port + 1);
if (nf_ct_expect_related(rtcp_exp) == 0)
break;
nf_ct_unexpect_related(rtp_exp);
}

if (port == 0)
return NF_DROP;

if (!mangle_sdp(skb, ctinfo, ct, newip, port, dptr, datalen)) {
nf_ct_unexpect_related(exp);
nf_ct_unexpect_related(rtp_exp);
nf_ct_unexpect_related(rtcp_exp);
return NF_DROP;
}
return NF_ACCEPT;
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58 changes: 38 additions & 20 deletions net/netfilter/nf_conntrack_sip.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -63,7 +63,9 @@ EXPORT_SYMBOL_GPL(nf_nat_sip_expect_hook);
unsigned int (*nf_nat_sdp_hook)(struct sk_buff *skb,
const char **dptr,
unsigned int *datalen,
struct nf_conntrack_expect *exp) __read_mostly;
struct nf_conntrack_expect *rtp_exp,
struct nf_conntrack_expect *rtcp_exp)
__read_mostly;
EXPORT_SYMBOL_GPL(nf_nat_sdp_hook);

static int string_len(const struct nf_conn *ct, const char *dptr,
Expand Down Expand Up @@ -659,18 +661,20 @@ static void flush_expectations(struct nf_conn *ct, bool media)
spin_unlock_bh(&nf_conntrack_lock);
}

static int set_expected_rtp(struct sk_buff *skb,
const char **dptr, unsigned int *datalen,
union nf_inet_addr *daddr, __be16 port)
static int set_expected_rtp_rtcp(struct sk_buff *skb,
const char **dptr, unsigned int *datalen,
union nf_inet_addr *daddr, __be16 port)
{
struct nf_conntrack_expect *exp;
struct nf_conntrack_expect *exp, *rtp_exp, *rtcp_exp;
enum ip_conntrack_info ctinfo;
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
union nf_inet_addr *saddr;
struct nf_conntrack_tuple tuple;
int family = ct->tuplehash[!dir].tuple.src.l3num;
int skip_expect = 0, ret;
int skip_expect = 0, ret = NF_DROP;
u_int16_t base_port;
__be16 rtp_port, rtcp_port;
typeof(nf_nat_sdp_hook) nf_nat_sdp;

saddr = NULL;
Expand Down Expand Up @@ -704,23 +708,37 @@ static int set_expected_rtp(struct sk_buff *skb,
if (skip_expect)
return NF_ACCEPT;

exp = nf_ct_expect_alloc(ct);
if (exp == NULL)
return NF_DROP;
nf_ct_expect_init(exp, SIP_EXPECT_AUDIO, family, saddr, daddr,
IPPROTO_UDP, NULL, &port);
base_port = ntohs(tuple.dst.u.udp.port) & ~1;
rtp_port = htons(base_port);
rtcp_port = htons(base_port + 1);

rtp_exp = nf_ct_expect_alloc(ct);
if (rtp_exp == NULL)
goto err1;
nf_ct_expect_init(rtp_exp, SIP_EXPECT_AUDIO, family, saddr, daddr,
IPPROTO_UDP, NULL, &rtp_port);

rtcp_exp = nf_ct_expect_alloc(ct);
if (rtcp_exp == NULL)
goto err2;
nf_ct_expect_init(rtcp_exp, SIP_EXPECT_AUDIO, family, saddr, daddr,
IPPROTO_UDP, NULL, &rtcp_port);

nf_nat_sdp = rcu_dereference(nf_nat_sdp_hook);
if (nf_nat_sdp && ct->status & IPS_NAT_MASK)
ret = nf_nat_sdp(skb, dptr, datalen, exp);
ret = nf_nat_sdp(skb, dptr, datalen, rtp_exp, rtcp_exp);
else {
if (nf_ct_expect_related(exp) != 0)
ret = NF_DROP;
else
ret = NF_ACCEPT;
if (nf_ct_expect_related(rtp_exp) == 0) {
if (nf_ct_expect_related(rtcp_exp) != 0)
nf_ct_unexpect_related(rtp_exp);
else
ret = NF_ACCEPT;
}
}
nf_ct_expect_put(exp);

nf_ct_expect_put(rtcp_exp);
err2:
nf_ct_expect_put(rtp_exp);
err1:
return ret;
}

Expand Down Expand Up @@ -758,7 +776,7 @@ static int process_sdp(struct sk_buff *skb,
if (port < 1024 || port > 65535)
return NF_DROP;

return set_expected_rtp(skb, dptr, datalen, &addr, htons(port));
return set_expected_rtp_rtcp(skb, dptr, datalen, &addr, htons(port));
}
static int process_invite_response(struct sk_buff *skb,
const char **dptr, unsigned int *datalen,
Expand Down Expand Up @@ -1101,7 +1119,7 @@ static const struct nf_conntrack_expect_policy sip_exp_policy[SIP_EXPECT_MAX + 1
.timeout = 3 * 60,
},
[SIP_EXPECT_AUDIO] = {
.max_expected = IP_CT_DIR_MAX,
.max_expected = 2 * IP_CT_DIR_MAX,
.timeout = 3 * 60,
},
};
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