* [PATCH 5/8][CONNTRACK] Introduce the pickup facilities to take over TCP connections
@ 2006-07-25 13:25 Pablo Neira Ayuso
2006-08-08 10:33 ` Patrick McHardy
0 siblings, 1 reply; 2+ messages in thread
From: Pablo Neira Ayuso @ 2006-07-25 13:25 UTC (permalink / raw)
To: Netfilter Development Mailinglist, Jozsef Kadlecsik
Cc: Harald Welte, Patrick McHardy
[-- 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)
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH 5/8][CONNTRACK] Introduce the pickup facilities to take over TCP connections
2006-07-25 13:25 [PATCH 5/8][CONNTRACK] Introduce the pickup facilities to take over TCP connections Pablo Neira Ayuso
@ 2006-08-08 10:33 ` Patrick McHardy
0 siblings, 0 replies; 2+ messages in thread
From: Patrick McHardy @ 2006-08-08 10:33 UTC (permalink / raw)
To: Pablo Neira Ayuso
Cc: Harald Welte, Netfilter Development Mailinglist, Jozsef Kadlecsik
Pablo Neira Ayuso wrote:
> 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>
>
>
> ------------------------------------------------------------------------
>
> [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;
This will also set all other flags from seen[1] in seen[0]. RFC 1323
also says quite the opposite, both sides must send a wscale option to
enable it. For unreplied connections this will do the wrong thing.
And we should have an option to unset it, also for the case where
we're synchronizing the state of an unreplied connection. I also
think it would be better to add netlink attributes for the entire
flags mask, for example IP_CT_TCP_FLAG_SACK_PERM also wants to be
synchronized I guess.
^ permalink raw reply [flat|nested] 2+ messages in thread
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2006-07-25 13:25 [PATCH 5/8][CONNTRACK] Introduce the pickup facilities to take over TCP connections Pablo Neira Ayuso
2006-08-08 10:33 ` Patrick McHardy
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