From: Pablo Neira Ayuso <pablo@netfilter.org>
To: Netfilter Development Mailinglist
<netfilter-devel@lists.netfilter.org>,
Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Cc: Harald Welte <laforge@netfilter.org>, Patrick McHardy <kaber@trash.net>
Subject: [PATCH 5/8][CONNTRACK] Introduce the pickup facilities to take over TCP connections
Date: Tue, 25 Jul 2006 15:25:46 +0200 [thread overview]
Message-ID: <44C61BDA.7050505@netfilter.org> (raw)
[-- Attachment #1: Type: text/plain, Size: 559 bytes --]
This patch introduces a new flag called IPS_PICKUP that forces the
protocol handler to pick up the required information in order to ensure
that the connection will reach a successful state.
Two new ctnetlink attributes are also introduced to inject the window
scale factor since TCP window tracking could need it to take over the
connection properly.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
--
The dawn of the fourth age of Linux firewalling is coming; a time of
great struggle and heroic deeds -- J.Kadlecsik got inspired by J.Morris
[-- Attachment #2: 05pickup.patch --]
[-- Type: text/plain, Size: 12283 bytes --]
[CONNTRACK] Introduce the pickup facilities to take over TCP connections
This patch introduces a new flag called IPS_PICKUP that forces the protocol
handler to pick up the required information in order to ensure that the
connection will reach a successful state.
Two new ctnetlink attributes are also introduced to inject the window scale
factor since TCP window tracking could need it to take over the connection
properly.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Index: net-2.6/net/ipv4/netfilter/ip_conntrack_proto_tcp.c
===================================================================
--- net-2.6.orig/net/ipv4/netfilter/ip_conntrack_proto_tcp.c 2006-07-14 17:01:02.000000000 +0200
+++ net-2.6/net/ipv4/netfilter/ip_conntrack_proto_tcp.c 2006-07-14 17:46:59.000000000 +0200
@@ -346,6 +346,12 @@ static int tcp_to_nfattr(struct sk_buff
nest_parms = NFA_NEST(skb, CTA_PROTOINFO_TCP);
NFA_PUT(skb, CTA_PROTOINFO_TCP_STATE, sizeof(u_int8_t),
&ct->proto.tcp.state);
+ /* window scale factor: original direction (SYN) */
+ NFA_PUT(skb, CTA_PROTOINFO_TCP_WSCALE_ORIGINAL, sizeof(u_int8_t),
+ &ct->proto.tcp.seen[0].td_scale);
+ /* window scale factor: reply direction (SYN+ACK) */
+ NFA_PUT(skb, CTA_PROTOINFO_TCP_WSCALE_REPLY, sizeof(u_int8_t),
+ &ct->proto.tcp.seen[1].td_scale);
read_unlock_bh(&tcp_lock);
NFA_NEST_END(skb, nest_parms);
@@ -358,7 +364,9 @@ nfattr_failure:
}
static const size_t cta_min_tcp[CTA_PROTOINFO_TCP_MAX] = {
- [CTA_PROTOINFO_TCP_STATE-1] = sizeof(u_int8_t),
+ [CTA_PROTOINFO_TCP_STATE-1] = sizeof(u_int8_t),
+ [CTA_PROTOINFO_TCP_WSCALE_ORIGINAL-1] = sizeof(u_int8_t),
+ [CTA_PROTOINFO_TCP_WSCALE_REPLY-1] = sizeof(u_int8_t),
};
static int nfattr_to_tcp(struct nfattr *cda[], struct ip_conntrack *ct)
@@ -382,6 +390,24 @@ static int nfattr_to_tcp(struct nfattr *
write_lock_bh(&tcp_lock);
ct->proto.tcp.state =
*(u_int8_t *)NFA_DATA(tb[CTA_PROTOINFO_TCP_STATE-1]);
+ /* window scale factor: original direction (SYN) */
+ if (tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL-1])
+ ct->proto.tcp.seen[0].td_scale =
+ *(u_int8_t *)NFA_DATA(tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL-1]);
+ /* window scale factor: reply direction (SYN+ACK) */
+ if (tb[CTA_PROTOINFO_TCP_WSCALE_REPLY-1])
+ ct->proto.tcp.seen[1].td_scale =
+ *(u_int8_t *)NFA_DATA(tb[CTA_PROTOINFO_TCP_WSCALE_REPLY-1]);
+ /* set WINDOW_SCALE flag */
+ if (tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL-1] ||
+ tb[CTA_PROTOINFO_TCP_WSCALE_REPLY-1]) {
+ /*
+ * we have to assume that both sides have
+ * sent Window Scale options (RFC 1323)
+ */
+ ct->proto.tcp.seen[0].flags |=
+ ct->proto.tcp.seen[1].flags |= IP_CT_TCP_FLAG_WINDOW_SCALE;
+ }
write_unlock_bh(&tcp_lock);
return 0;
@@ -425,10 +451,10 @@ static unsigned int get_conntrack_index(
we doesn't have to deal with fragments.
*/
-static inline __u32 segment_seq_plus_len(__u32 seq,
- size_t len,
- struct iphdr *iph,
- struct tcphdr *tcph)
+static inline __u32 segment_seq_plus_len(const __u32 seq,
+ const size_t len,
+ const struct iphdr *iph,
+ const struct tcphdr *tcph)
{
return (seq + len - (iph->ihl + tcph->doff)*4
+ (tcph->syn ? 1 : 0) + (tcph->fin ? 1 : 0));
@@ -890,6 +916,28 @@ static int tcp_error(struct sk_buff *skb
return NF_ACCEPT;
}
+static void tcp_pickup_connection(struct ip_conntrack *conntrack,
+ const struct sk_buff *skb,
+ const struct iphdr *iph,
+ const struct tcphdr *th)
+{
+ conntrack->proto.tcp.seen[0].td_end =
+ segment_seq_plus_len(ntohl(th->seq), skb->len, iph, th);
+ conntrack->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
+ if (conntrack->proto.tcp.seen[0].td_maxwin == 0)
+ conntrack->proto.tcp.seen[0].td_maxwin = 1;
+ conntrack->proto.tcp.seen[0].td_maxend =
+ conntrack->proto.tcp.seen[0].td_end +
+ conntrack->proto.tcp.seen[0].td_maxwin;
+ conntrack->proto.tcp.seen[0].td_scale = 0;
+
+ /* We assume SACK. Should we assume window scaling too? */
+ conntrack->proto.tcp.seen[0].flags |=
+ conntrack->proto.tcp.seen[1].flags |= IP_CT_TCP_FLAG_SACK_PERM;
+ conntrack->proto.tcp.seen[0].loose =
+ conntrack->proto.tcp.seen[1].loose = ip_ct_tcp_loose;
+}
+
/* Returns verdict for packet, or -1 for invalid. */
static int tcp_packet(struct ip_conntrack *conntrack,
const struct sk_buff *skb,
@@ -907,6 +955,14 @@ static int tcp_packet(struct ip_conntrac
BUG_ON(th == NULL);
write_lock_bh(&tcp_lock);
+
+ /*
+ * This conntrack was added via ctnetlink or ct_sync and needs to
+ * take over sequence tracking in order to work properly.
+ */
+ if (test_and_clear_bit(IPS_PICKUP, &conntrack->status))
+ tcp_pickup_connection(conntrack, skb, iph, th);
+
old_state = conntrack->proto.tcp.state;
dir = CTINFO2DIR(ctinfo);
index = get_conntrack_index(th);
@@ -1116,22 +1172,7 @@ static int tcp_new(struct ip_conntrack *
* its history is lost for us.
* Let's try to use the data from the packet.
*/
- conntrack->proto.tcp.seen[0].td_end =
- segment_seq_plus_len(ntohl(th->seq), skb->len,
- iph, th);
- conntrack->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
- if (conntrack->proto.tcp.seen[0].td_maxwin == 0)
- conntrack->proto.tcp.seen[0].td_maxwin = 1;
- conntrack->proto.tcp.seen[0].td_maxend =
- conntrack->proto.tcp.seen[0].td_end +
- conntrack->proto.tcp.seen[0].td_maxwin;
- conntrack->proto.tcp.seen[0].td_scale = 0;
-
- /* We assume SACK. Should we assume window scaling too? */
- conntrack->proto.tcp.seen[0].flags =
- conntrack->proto.tcp.seen[1].flags = IP_CT_TCP_FLAG_SACK_PERM;
- conntrack->proto.tcp.seen[0].loose =
- conntrack->proto.tcp.seen[1].loose = ip_ct_tcp_loose;
+ tcp_pickup_connection(conntrack, skb, iph, th);
}
conntrack->proto.tcp.seen[1].td_end = 0;
Index: net-2.6/include/linux/netfilter/nf_conntrack_common.h
===================================================================
--- net-2.6.orig/include/linux/netfilter/nf_conntrack_common.h 2006-07-14 17:01:02.000000000 +0200
+++ net-2.6/include/linux/netfilter/nf_conntrack_common.h 2006-07-14 17:02:02.000000000 +0200
@@ -73,6 +73,10 @@ enum ip_conntrack_status {
/* Connection has fixed timeout. */
IPS_FIXED_TIMEOUT_BIT = 10,
IPS_FIXED_TIMEOUT = (1 << IPS_FIXED_TIMEOUT_BIT),
+
+ /* Pick up connection information if required */
+ IPS_PICKUP_BIT = 11,
+ IPS_PICKUP = (1 << IPS_PICKUP_BIT),
};
/* Connection tracking event bits */
Index: net-2.6/net/netfilter/nf_conntrack_proto_tcp.c
===================================================================
--- net-2.6.orig/net/netfilter/nf_conntrack_proto_tcp.c 2006-07-14 17:01:02.000000000 +0200
+++ net-2.6/net/netfilter/nf_conntrack_proto_tcp.c 2006-07-14 18:02:45.000000000 +0200
@@ -381,10 +381,10 @@ static unsigned int get_conntrack_index(
we doesn't have to deal with fragments.
*/
-static inline __u32 segment_seq_plus_len(__u32 seq,
- size_t len,
- unsigned int dataoff,
- struct tcphdr *tcph)
+static inline __u32 segment_seq_plus_len(const __u32 seq,
+ const size_t len,
+ const unsigned int dataoff,
+ const struct tcphdr *tcph)
{
/* XXX Should I use payload length field in IP/IPv6 header ?
* - YK */
@@ -850,6 +850,28 @@ static int tcp_error(struct sk_buff *skb
return NF_ACCEPT;
}
+static void tcp_pickup_connection(struct nf_conn *conntrack,
+ const struct sk_buff *skb,
+ const unsigned int dataoff,
+ const struct tcphdr *th)
+{
+ conntrack->proto.tcp.seen[0].td_end =
+ segment_seq_plus_len(ntohl(th->seq), skb->len, dataoff, th);
+ conntrack->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
+ if (conntrack->proto.tcp.seen[0].td_maxwin == 0)
+ conntrack->proto.tcp.seen[0].td_maxwin = 1;
+ conntrack->proto.tcp.seen[0].td_maxend =
+ conntrack->proto.tcp.seen[0].td_end +
+ conntrack->proto.tcp.seen[0].td_maxwin;
+ conntrack->proto.tcp.seen[0].td_scale = 0;
+
+ /* We assume SACK. Should we assume window scaling too? */
+ conntrack->proto.tcp.seen[0].flags |=
+ conntrack->proto.tcp.seen[1].flags |= IP_CT_TCP_FLAG_SACK_PERM;
+ conntrack->proto.tcp.seen[0].loose =
+ conntrack->proto.tcp.seen[1].loose = nf_ct_tcp_loose;
+}
+
/* Returns verdict for packet, or -1 for invalid. */
static int tcp_packet(struct nf_conn *conntrack,
const struct sk_buff *skb,
@@ -868,6 +890,14 @@ static int tcp_packet(struct nf_conn *co
BUG_ON(th == NULL);
write_lock_bh(&tcp_lock);
+
+ /*
+ * This conntrack was added via ctnetlink or ct_sync and needs to
+ * take over sequence tracking in order to work properly.
+ */
+ if (test_and_clear_bit(IPS_PICKUP, &conntrack->status))
+ tcp_pickup_connection(conntrack, skb, dataoff, th);
+
old_state = conntrack->proto.tcp.state;
dir = CTINFO2DIR(ctinfo);
index = get_conntrack_index(th);
@@ -1075,22 +1105,7 @@ static int tcp_new(struct nf_conn *connt
* its history is lost for us.
* Let's try to use the data from the packet.
*/
- conntrack->proto.tcp.seen[0].td_end =
- segment_seq_plus_len(ntohl(th->seq), skb->len,
- dataoff, th);
- conntrack->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
- if (conntrack->proto.tcp.seen[0].td_maxwin == 0)
- conntrack->proto.tcp.seen[0].td_maxwin = 1;
- conntrack->proto.tcp.seen[0].td_maxend =
- conntrack->proto.tcp.seen[0].td_end +
- conntrack->proto.tcp.seen[0].td_maxwin;
- conntrack->proto.tcp.seen[0].td_scale = 0;
-
- /* We assume SACK. Should we assume window scaling too? */
- conntrack->proto.tcp.seen[0].flags =
- conntrack->proto.tcp.seen[1].flags = IP_CT_TCP_FLAG_SACK_PERM;
- conntrack->proto.tcp.seen[0].loose =
- conntrack->proto.tcp.seen[1].loose = nf_ct_tcp_loose;
+ tcp_pickup_connection(conntrack, skb, dataoff, th);
}
conntrack->proto.tcp.seen[1].td_end = 0;
@@ -1126,6 +1141,12 @@ static int tcp_to_nfattr(struct sk_buff
nest_parms = NFA_NEST(skb, CTA_PROTOINFO_TCP);
NFA_PUT(skb, CTA_PROTOINFO_TCP_STATE, sizeof(u_int8_t),
&ct->proto.tcp.state);
+ /* window scale factor: original direction (SYN) */
+ NFA_PUT(skb, CTA_PROTOINFO_TCP_WSCALE_ORIGINAL, sizeof(u_int8_t),
+ &ct->proto.tcp.seen[0].td_scale);
+ /* window scale factor: reply direction (SYN+ACK) */
+ NFA_PUT(skb, CTA_PROTOINFO_TCP_WSCALE_REPLY, sizeof(u_int8_t),
+ &ct->proto.tcp.seen[1].td_scale);
read_unlock_bh(&tcp_lock);
NFA_NEST_END(skb, nest_parms);
@@ -1138,7 +1159,9 @@ nfattr_failure:
}
static const size_t cta_min_tcp[CTA_PROTOINFO_TCP_MAX] = {
- [CTA_PROTOINFO_TCP_STATE-1] = sizeof(u_int8_t),
+ [CTA_PROTOINFO_TCP_STATE-1] = sizeof(u_int8_t),
+ [CTA_PROTOINFO_TCP_WSCALE_ORIGINAL-1] = sizeof(u_int8_t),
+ [CTA_PROTOINFO_TCP_WSCALE_REPLY-1] = sizeof(u_int8_t),
};
static int nfattr_to_tcp(struct nfattr *cda[], struct nf_conn *ct)
@@ -1162,6 +1185,24 @@ static int nfattr_to_tcp(struct nfattr *
write_lock_bh(&tcp_lock);
ct->proto.tcp.state =
*(u_int8_t *)NFA_DATA(tb[CTA_PROTOINFO_TCP_STATE-1]);
+ /* window scale factor: original direction (SYN) */
+ if (tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL-1])
+ ct->proto.tcp.seen[0].td_scale =
+ *(u_int8_t *)NFA_DATA(tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL-1]);
+ /* window scale factor: reply direction (SYN+ACK) */
+ if (tb[CTA_PROTOINFO_TCP_WSCALE_REPLY-1])
+ ct->proto.tcp.seen[1].td_scale =
+ *(u_int8_t *)NFA_DATA(tb[CTA_PROTOINFO_TCP_WSCALE_REPLY-1]);
+ /* set WINDOW_SCALE flag */
+ if (tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL-1] ||
+ tb[CTA_PROTOINFO_TCP_WSCALE_REPLY-1]) {
+ /*
+ * we have to assume that both sides have
+ * sent Window Scale options (RFC 1323)
+ */
+ ct->proto.tcp.seen[0].flags |=
+ ct->proto.tcp.seen[1].flags |= IP_CT_TCP_FLAG_WINDOW_SCALE;
+ }
write_unlock_bh(&tcp_lock);
return 0;
Index: net-2.6/include/linux/netfilter/nfnetlink_conntrack.h
===================================================================
--- net-2.6.orig/include/linux/netfilter/nfnetlink_conntrack.h 2006-07-14 17:01:02.000000000 +0200
+++ net-2.6/include/linux/netfilter/nfnetlink_conntrack.h 2006-07-14 17:16:17.000000000 +0200
@@ -83,6 +83,8 @@ enum ctattr_protoinfo {
enum ctattr_protoinfo_tcp {
CTA_PROTOINFO_TCP_UNSPEC,
CTA_PROTOINFO_TCP_STATE,
+ CTA_PROTOINFO_TCP_WSCALE_ORIGINAL,
+ CTA_PROTOINFO_TCP_WSCALE_REPLY,
__CTA_PROTOINFO_TCP_MAX
};
#define CTA_PROTOINFO_TCP_MAX (__CTA_PROTOINFO_TCP_MAX - 1)
next reply other threads:[~2006-07-25 13:25 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-07-25 13:25 Pablo Neira Ayuso [this message]
2006-08-08 10:33 ` [PATCH 5/8][CONNTRACK] Introduce the pickup facilities to take over TCP connections Patrick McHardy
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