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authorMichal Kubeček <mkubecek@suse.cz>2015-07-17 16:17:56 +0200
committerPablo Neira Ayuso <pablo@netfilter.org>2015-07-30 12:59:25 +0200
commitd7ee3519042798be6224e97f259ed47a63da4620 (patch)
treefb018a2d4a384b3bcd3c25871e8450e695603f54 /net/netfilter
parent3bbd14e0a2e3a988b1b5fe702a2539bd8d0ec622 (diff)
netfilter: nf_ct_sctp: minimal multihoming support
Currently nf_conntrack_proto_sctp module handles only packets between primary addresses used to establish the connection. Any packets between secondary addresses are classified as invalid so that usual firewall configurations drop them. Allowing HEARTBEAT and HEARTBEAT-ACK chunks to establish a new conntrack would allow traffic between secondary addresses to pass through. A more sophisticated solution based on the addresses advertised in the initial handshake (and possibly also later dynamic address addition and removal) would be much harder to implement. Moreover, in general we cannot assume to always see the initial handshake as it can be routed through a different path. The patch adds two new conntrack states: SCTP_CONNTRACK_HEARTBEAT_SENT - a HEARTBEAT chunk seen but not acked SCTP_CONNTRACK_HEARTBEAT_ACKED - a HEARTBEAT acked by HEARTBEAT-ACK State transition rules: - HEARTBEAT_SENT responds to usual chunks the same way as NONE (so that the behaviour changes as little as possible) - HEARTBEAT_ACKED responds to usual chunks the same way as ESTABLISHED does, except the resulting state is HEARTBEAT_ACKED rather than ESTABLISHED - previously existing states except NONE are preserved when HEARTBEAT or HEARTBEAT-ACK is seen - NONE (in the initial direction) changes to HEARTBEAT_SENT on HEARTBEAT and to CLOSED on HEARTBEAT-ACK - HEARTBEAT_SENT changes to HEARTBEAT_ACKED on HEARTBEAT-ACK in the reply direction - HEARTBEAT_SENT and HEARTBEAT_ACKED are preserved on HEARTBEAT and HEARTBEAT-ACK otherwise Normally, vtag is set from the INIT chunk for the reply direction and from the INIT-ACK chunk for the originating direction (i.e. each of these defines vtag value for the opposite direction). For secondary conntracks, we can't rely on seeing INIT/INIT-ACK and even if we have seen them, we would need to connect two different conntracks. Therefore simplified logic is applied: vtag of first packet in each direction (HEARTBEAT in the originating and HEARTBEAT-ACK in reply direction) is saved and all following packets in that direction are compared with this saved value. While INIT and INIT-ACK define vtag for the opposite direction, vtags extracted from HEARTBEAT and HEARTBEAT-ACK are always for their direction. Default timeout values for new states are HEARTBEAT_SENT: 30 seconds (default hb_interval) HEARTBEAT_ACKED: 210 seconds (hb_interval * path_max_retry + max_rto) (We cannot expect to see the shutdown sequence so that, unlike ESTABLISHED, the HEARTBEAT_ACKED timeout shouldn't be too long.) Signed-off-by: Michal Kubecek <mkubecek@suse.cz> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net/netfilter')
-rw-r--r--net/netfilter/nf_conntrack_proto_sctp.c101
1 files changed, 77 insertions, 24 deletions
diff --git a/net/netfilter/nf_conntrack_proto_sctp.c b/net/netfilter/nf_conntrack_proto_sctp.c
index b45da90fad32..67197731eb68 100644
--- a/net/netfilter/nf_conntrack_proto_sctp.c
+++ b/net/netfilter/nf_conntrack_proto_sctp.c
@@ -42,6 +42,8 @@ static const char *const sctp_conntrack_names[] = {
"SHUTDOWN_SENT",
"SHUTDOWN_RECD",
"SHUTDOWN_ACK_SENT",
+ "HEARTBEAT_SENT",
+ "HEARTBEAT_ACKED",
};
#define SECS * HZ
@@ -57,6 +59,8 @@ static unsigned int sctp_timeouts[SCTP_CONNTRACK_MAX] __read_mostly = {
[SCTP_CONNTRACK_SHUTDOWN_SENT] = 300 SECS / 1000,
[SCTP_CONNTRACK_SHUTDOWN_RECD] = 300 SECS / 1000,
[SCTP_CONNTRACK_SHUTDOWN_ACK_SENT] = 3 SECS,
+ [SCTP_CONNTRACK_HEARTBEAT_SENT] = 30 SECS,
+ [SCTP_CONNTRACK_HEARTBEAT_ACKED] = 210 SECS,
};
#define sNO SCTP_CONNTRACK_NONE
@@ -67,6 +71,8 @@ static unsigned int sctp_timeouts[SCTP_CONNTRACK_MAX] __read_mostly = {
#define sSS SCTP_CONNTRACK_SHUTDOWN_SENT
#define sSR SCTP_CONNTRACK_SHUTDOWN_RECD
#define sSA SCTP_CONNTRACK_SHUTDOWN_ACK_SENT
+#define sHS SCTP_CONNTRACK_HEARTBEAT_SENT
+#define sHA SCTP_CONNTRACK_HEARTBEAT_ACKED
#define sIV SCTP_CONNTRACK_MAX
/*
@@ -88,6 +94,10 @@ SHUTDOWN_ACK_SENT - We have seen a SHUTDOWN_ACK chunk in the direction opposite
to that of the SHUTDOWN chunk.
CLOSED - We have seen a SHUTDOWN_COMPLETE chunk in the direction of
the SHUTDOWN chunk. Connection is closed.
+HEARTBEAT_SENT - We have seen a HEARTBEAT in a new flow.
+HEARTBEAT_ACKED - We have seen a HEARTBEAT-ACK in the direction opposite to
+ that of the HEARTBEAT chunk. Secondary connection is
+ established.
*/
/* TODO
@@ -97,36 +107,40 @@ CLOSED - We have seen a SHUTDOWN_COMPLETE chunk in the direction of
- Check the error type in the reply dir before transitioning from
cookie echoed to closed.
- Sec 5.2.4 of RFC 2960
- - Multi Homing support.
+ - Full Multi Homing support.
*/
/* SCTP conntrack state transitions */
-static const u8 sctp_conntracks[2][9][SCTP_CONNTRACK_MAX] = {
+static const u8 sctp_conntracks[2][11][SCTP_CONNTRACK_MAX] = {
{
/* ORIGINAL */
-/* sNO, sCL, sCW, sCE, sES, sSS, sSR, sSA */
-/* init */ {sCW, sCW, sCW, sCE, sES, sSS, sSR, sSA},
-/* init_ack */ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sSA},
-/* abort */ {sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL},
-/* shutdown */ {sCL, sCL, sCW, sCE, sSS, sSS, sSR, sSA},
-/* shutdown_ack */ {sSA, sCL, sCW, sCE, sES, sSA, sSA, sSA},
-/* error */ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sSA},/* Can't have Stale cookie*/
-/* cookie_echo */ {sCL, sCL, sCE, sCE, sES, sSS, sSR, sSA},/* 5.2.4 - Big TODO */
-/* cookie_ack */ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sSA},/* Can't come in orig dir */
-/* shutdown_comp*/ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sCL}
+/* sNO, sCL, sCW, sCE, sES, sSS, sSR, sSA, sHS, sHA */
+/* init */ {sCW, sCW, sCW, sCE, sES, sSS, sSR, sSA, sCW, sHA},
+/* init_ack */ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sSA, sCL, sHA},
+/* abort */ {sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL},
+/* shutdown */ {sCL, sCL, sCW, sCE, sSS, sSS, sSR, sSA, sCL, sSS},
+/* shutdown_ack */ {sSA, sCL, sCW, sCE, sES, sSA, sSA, sSA, sSA, sHA},
+/* error */ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sSA, sCL, sHA},/* Can't have Stale cookie*/
+/* cookie_echo */ {sCL, sCL, sCE, sCE, sES, sSS, sSR, sSA, sCL, sHA},/* 5.2.4 - Big TODO */
+/* cookie_ack */ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sSA, sCL, sHA},/* Can't come in orig dir */
+/* shutdown_comp*/ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sCL, sCL, sHA},
+/* heartbeat */ {sHS, sCL, sCW, sCE, sES, sSS, sSR, sSA, sHS, sHA},
+/* heartbeat_ack*/ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sSA, sHS, sHA}
},
{
/* REPLY */
-/* sNO, sCL, sCW, sCE, sES, sSS, sSR, sSA */
-/* init */ {sIV, sCL, sCW, sCE, sES, sSS, sSR, sSA},/* INIT in sCL Big TODO */
-/* init_ack */ {sIV, sCL, sCW, sCE, sES, sSS, sSR, sSA},
-/* abort */ {sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL},
-/* shutdown */ {sIV, sCL, sCW, sCE, sSR, sSS, sSR, sSA},
-/* shutdown_ack */ {sIV, sCL, sCW, sCE, sES, sSA, sSA, sSA},
-/* error */ {sIV, sCL, sCW, sCL, sES, sSS, sSR, sSA},
-/* cookie_echo */ {sIV, sCL, sCW, sCE, sES, sSS, sSR, sSA},/* Can't come in reply dir */
-/* cookie_ack */ {sIV, sCL, sCW, sES, sES, sSS, sSR, sSA},
-/* shutdown_comp*/ {sIV, sCL, sCW, sCE, sES, sSS, sSR, sCL}
+/* sNO, sCL, sCW, sCE, sES, sSS, sSR, sSA, sHS, sHA */
+/* init */ {sIV, sCL, sCW, sCE, sES, sSS, sSR, sSA, sIV, sHA},/* INIT in sCL Big TODO */
+/* init_ack */ {sIV, sCL, sCW, sCE, sES, sSS, sSR, sSA, sIV, sHA},
+/* abort */ {sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sIV, sCL},
+/* shutdown */ {sIV, sCL, sCW, sCE, sSR, sSS, sSR, sSA, sIV, sSR},
+/* shutdown_ack */ {sIV, sCL, sCW, sCE, sES, sSA, sSA, sSA, sIV, sHA},
+/* error */ {sIV, sCL, sCW, sCL, sES, sSS, sSR, sSA, sIV, sHA},
+/* cookie_echo */ {sIV, sCL, sCW, sCE, sES, sSS, sSR, sSA, sIV, sHA},/* Can't come in reply dir */
+/* cookie_ack */ {sIV, sCL, sCW, sES, sES, sSS, sSR, sSA, sIV, sHA},
+/* shutdown_comp*/ {sIV, sCL, sCW, sCE, sES, sSS, sSR, sCL, sIV, sHA},
+/* heartbeat */ {sIV, sCL, sCW, sCE, sES, sSS, sSR, sSA, sHS, sHA},
+/* heartbeat_ack*/ {sIV, sCL, sCW, sCE, sES, sSS, sSR, sSA, sHA, sHA}
}
};
@@ -278,9 +292,16 @@ static int sctp_new_state(enum ip_conntrack_dir dir,
pr_debug("SCTP_CID_SHUTDOWN_COMPLETE\n");
i = 8;
break;
+ case SCTP_CID_HEARTBEAT:
+ pr_debug("SCTP_CID_HEARTBEAT");
+ i = 9;
+ break;
+ case SCTP_CID_HEARTBEAT_ACK:
+ pr_debug("SCTP_CID_HEARTBEAT_ACK");
+ i = 10;
+ break;
default:
- /* Other chunks like DATA, SACK, HEARTBEAT and
- its ACK do not cause a change in state */
+ /* Other chunks like DATA or SACK do not change the state */
pr_debug("Unknown chunk type, Will stay in %s\n",
sctp_conntrack_names[cur_state]);
return cur_state;
@@ -329,6 +350,8 @@ static int sctp_packet(struct nf_conn *ct,
!test_bit(SCTP_CID_COOKIE_ECHO, map) &&
!test_bit(SCTP_CID_ABORT, map) &&
!test_bit(SCTP_CID_SHUTDOWN_ACK, map) &&
+ !test_bit(SCTP_CID_HEARTBEAT, map) &&
+ !test_bit(SCTP_CID_HEARTBEAT_ACK, map) &&
sh->vtag != ct->proto.sctp.vtag[dir]) {
pr_debug("Verification tag check failed\n");
goto out;
@@ -357,6 +380,16 @@ static int sctp_packet(struct nf_conn *ct,
/* Sec 8.5.1 (D) */
if (sh->vtag != ct->proto.sctp.vtag[dir])
goto out_unlock;
+ } else if (sch->type == SCTP_CID_HEARTBEAT ||
+ sch->type == SCTP_CID_HEARTBEAT_ACK) {
+ if (ct->proto.sctp.vtag[dir] == 0) {
+ pr_debug("Setting vtag %x for dir %d\n",
+ sh->vtag, dir);
+ ct->proto.sctp.vtag[dir] = sh->vtag;
+ } else if (sh->vtag != ct->proto.sctp.vtag[dir]) {
+ pr_debug("Verification tag check failed\n");
+ goto out_unlock;
+ }
}
old_state = ct->proto.sctp.state;
@@ -466,6 +499,10 @@ static bool sctp_new(struct nf_conn *ct, const struct sk_buff *skb,
/* Sec 8.5.1 (A) */
return false;
}
+ } else if (sch->type == SCTP_CID_HEARTBEAT) {
+ pr_debug("Setting vtag %x for secondary conntrack\n",
+ sh->vtag);
+ ct->proto.sctp.vtag[IP_CT_DIR_ORIGINAL] = sh->vtag;
}
/* If it is a shutdown ack OOTB packet, we expect a return
shutdown complete, otherwise an ABORT Sec 8.4 (5) and (8) */
@@ -610,6 +647,8 @@ sctp_timeout_nla_policy[CTA_TIMEOUT_SCTP_MAX+1] = {
[CTA_TIMEOUT_SCTP_SHUTDOWN_SENT] = { .type = NLA_U32 },
[CTA_TIMEOUT_SCTP_SHUTDOWN_RECD] = { .type = NLA_U32 },
[CTA_TIMEOUT_SCTP_SHUTDOWN_ACK_SENT] = { .type = NLA_U32 },
+ [CTA_TIMEOUT_SCTP_HEARTBEAT_SENT] = { .type = NLA_U32 },
+ [CTA_TIMEOUT_SCTP_HEARTBEAT_ACKED] = { .type = NLA_U32 },
};
#endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
@@ -658,6 +697,18 @@ static struct ctl_table sctp_sysctl_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec_jiffies,
},
+ {
+ .procname = "nf_conntrack_sctp_timeout_heartbeat_sent",
+ .maxlen = sizeof(unsigned int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_jiffies,
+ },
+ {
+ .procname = "nf_conntrack_sctp_timeout_heartbeat_acked",
+ .maxlen = sizeof(unsigned int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_jiffies,
+ },
{ }
};
@@ -730,6 +781,8 @@ static int sctp_kmemdup_sysctl_table(struct nf_proto_net *pn,
pn->ctl_table[4].data = &sn->timeouts[SCTP_CONNTRACK_SHUTDOWN_SENT];
pn->ctl_table[5].data = &sn->timeouts[SCTP_CONNTRACK_SHUTDOWN_RECD];
pn->ctl_table[6].data = &sn->timeouts[SCTP_CONNTRACK_SHUTDOWN_ACK_SENT];
+ pn->ctl_table[7].data = &sn->timeouts[SCTP_CONNTRACK_HEARTBEAT_SENT];
+ pn->ctl_table[8].data = &sn->timeouts[SCTP_CONNTRACK_HEARTBEAT_ACKED];
#endif
return 0;
}

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