netfilter: conntrack: unify established states for SCTP paths

An SCTP endpoint can start an association through a path and tear it
down over another one. That means the initial path will not see the
shutdown sequence, and the conntrack entry will remain in ESTABLISHED
state for 5 days.

By merging the HEARTBEAT_ACKED and ESTABLISHED states into one
ESTABLISHED state, there remains no difference between a primary or
secondary path. The timeout for the merged ESTABLISHED state is set to
210 seconds (hb_interval * max_path_retrans + rto_max). So, even if a
path doesn't see the shutdown sequence, it will expire in a reasonable
amount of time.

With this change in place, there is now more than one state from which
we can transition to ESTABLISHED, COOKIE_ECHOED and HEARTBEAT_SENT, so
handle the setting of ASSURED bit whenever a state change has happened
and the new state is ESTABLISHED. Removed the check for dir==REPLY since
the transition to ESTABLISHED can happen only in the reply direction.

Fixes: 9fb9cbb1082d ("[NETFILTER]: Add nf_conntrack subsystem.")
Signed-off-by: Sriram Yagnaraman <[e-mail]>
Signed-off-by: Pablo Neira Ayuso <[e-mail]>

Documentation/networking/nf_conntrack-sysctl.rst

···
 	default 3
 
 nf_conntrack_sctp_timeout_established - INTEGER (seconds)
-	default 432000 (5 days)
+	default 210
+
+	Default is set to (hb_interval * path_max_retrans + rto_max)
 
 nf_conntrack_sctp_timeout_shutdown_sent - INTEGER (seconds)
 	default 0.3
···
 
 	This timeout is used to setup conntrack entry on secondary paths.
 	Default is set to hb_interval.
-
-nf_conntrack_sctp_timeout_heartbeat_acked - INTEGER (seconds)
-	default 210
-
-	This timeout is used to setup conntrack entry on secondary paths.
-	Default is set to (hb_interval * path_max_retrans + rto_max)
 
 nf_conntrack_udp_timeout - INTEGER (seconds)
 	default 30

include/uapi/linux/netfilter/nf_conntrack_sctp.h

···
 	SCTP_CONNTRACK_SHUTDOWN_RECD,
 	SCTP_CONNTRACK_SHUTDOWN_ACK_SENT,
 	SCTP_CONNTRACK_HEARTBEAT_SENT,
-	SCTP_CONNTRACK_HEARTBEAT_ACKED,
+	SCTP_CONNTRACK_HEARTBEAT_ACKED,	/* no longer used */
 	SCTP_CONNTRACK_MAX
 };
 

include/uapi/linux/netfilter/nfnetlink_cttimeout.h

···
 	CTA_TIMEOUT_SCTP_SHUTDOWN_RECD,
 	CTA_TIMEOUT_SCTP_SHUTDOWN_ACK_SENT,
 	CTA_TIMEOUT_SCTP_HEARTBEAT_SENT,
-	CTA_TIMEOUT_SCTP_HEARTBEAT_ACKED,
+	CTA_TIMEOUT_SCTP_HEARTBEAT_ACKED, /* no longer used */
 	__CTA_TIMEOUT_SCTP_MAX
 };
 #define CTA_TIMEOUT_SCTP_MAX (__CTA_TIMEOUT_SCTP_MAX - 1)

net/netfilter/nf_conntrack_proto_sctp.c

···
 #include <net/netfilter/nf_conntrack_ecache.h>
 #include <net/netfilter/nf_conntrack_timeout.h>
 
-/* FIXME: Examine ipfilter's timeouts and conntrack transitions more
-   closely.  They're more complex. --RR
-
-   And so for me for SCTP :D -Kiran */
-
 static const char *const sctp_conntrack_names[] = {
-	"NONE",
-	"CLOSED",
-	"COOKIE_WAIT",
-	"COOKIE_ECHOED",
-	"ESTABLISHED",
-	"SHUTDOWN_SENT",
-	"SHUTDOWN_RECD",
-	"SHUTDOWN_ACK_SENT",
-	"HEARTBEAT_SENT",
-	"HEARTBEAT_ACKED",
+	[SCTP_CONNTRACK_NONE]			= "NONE",
+	[SCTP_CONNTRACK_CLOSED]			= "CLOSED",
+	[SCTP_CONNTRACK_COOKIE_WAIT]		= "COOKIE_WAIT",
+	[SCTP_CONNTRACK_COOKIE_ECHOED]		= "COOKIE_ECHOED",
+	[SCTP_CONNTRACK_ESTABLISHED]		= "ESTABLISHED",
+	[SCTP_CONNTRACK_SHUTDOWN_SENT]		= "SHUTDOWN_SENT",
+	[SCTP_CONNTRACK_SHUTDOWN_RECD]		= "SHUTDOWN_RECD",
+	[SCTP_CONNTRACK_SHUTDOWN_ACK_SENT]	= "SHUTDOWN_ACK_SENT",
+	[SCTP_CONNTRACK_HEARTBEAT_SENT]		= "HEARTBEAT_SENT",
 };
 
 #define SECS  * HZ
···
 	[SCTP_CONNTRACK_CLOSED]			= 10 SECS,
 	[SCTP_CONNTRACK_COOKIE_WAIT]		= 3 SECS,
 	[SCTP_CONNTRACK_COOKIE_ECHOED]		= 3 SECS,
-	[SCTP_CONNTRACK_ESTABLISHED]		= 5 DAYS,
+	[SCTP_CONNTRACK_ESTABLISHED]		= 210 SECS,
 	[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	SCTP_FLAG_HEARTBEAT_VTAG_FAILED	1
···
 #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
 
 /*
···
 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
···
 static const u8 sctp_conntracks[2][11][SCTP_CONNTRACK_MAX] = {
 	{
 /*	ORIGINAL	*/
-/*                  sNO, sCL, sCW, sCE, sES, sSS, sSR, sSA, sHS, sHA */
-/* init         */ {sCL, sCL, 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}
+/*                  sNO, sCL, sCW, sCE, sES, sSS, sSR, sSA, sHS */
+/* init         */ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sSA, sCW},
+/* init_ack     */ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sSA, sCL},
+/* abort        */ {sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL},
+/* shutdown     */ {sCL, sCL, sCW, sCE, sSS, sSS, sSR, sSA, sCL},
+/* shutdown_ack */ {sSA, sCL, sCW, sCE, sES, sSA, sSA, sSA, sSA},
+/* error        */ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sSA, sCL},/* Can't have Stale cookie*/
+/* cookie_echo  */ {sCL, sCL, sCE, sCE, sES, sSS, sSR, sSA, sCL},/* 5.2.4 - Big TODO */
+/* cookie_ack   */ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sSA, sCL},/* Can't come in orig dir */
+/* shutdown_comp*/ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sCL, sCL},
+/* heartbeat    */ {sHS, sCL, sCW, sCE, sES, sSS, sSR, sSA, sHS},
+/* heartbeat_ack*/ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sSA, sHS},
 	},
 	{
 /*	REPLY	*/
-/*                  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, sCW, 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}
+/*                  sNO, sCL, sCW, sCE, sES, sSS, sSR, sSA, sHS */
+/* init         */ {sIV, sCL, sCW, sCE, sES, sSS, sSR, sSA, sIV},/* INIT in sCL Big TODO */
+/* init_ack     */ {sIV, sCW, sCW, sCE, sES, sSS, sSR, sSA, sIV},
+/* abort        */ {sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sIV},
+/* shutdown     */ {sIV, sCL, sCW, sCE, sSR, sSS, sSR, sSA, sIV},
+/* shutdown_ack */ {sIV, sCL, sCW, sCE, sES, sSA, sSA, sSA, sIV},
+/* error        */ {sIV, sCL, sCW, sCL, sES, sSS, sSR, sSA, sIV},
+/* cookie_echo  */ {sIV, sCL, sCW, sCE, sES, sSS, sSR, sSA, sIV},/* Can't come in reply dir */
+/* cookie_ack   */ {sIV, sCL, sCW, sES, sES, sSS, sSR, sSA, sIV},
+/* shutdown_comp*/ {sIV, sCL, sCW, sCE, sES, sSS, sSR, sCL, sIV},
+/* heartbeat    */ {sIV, sCL, sCW, sCE, sES, sSS, sSR, sSA, sHS},
+/* heartbeat_ack*/ {sIV, sCL, sCW, sCE, sES, sSS, sSR, sSA, sES},
 	}
 };
 
···
 		}
 
 		ct->proto.sctp.state = new_state;
-		if (old_state != new_state)
+		if (old_state != new_state) {
 			nf_conntrack_event_cache(IPCT_PROTOINFO, ct);
+			if (new_state == SCTP_CONNTRACK_ESTABLISHED &&
+			    !test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
+				nf_conntrack_event_cache(IPCT_ASSURED, ct);
+		}
 	}
 	spin_unlock_bh(&ct->lock);
 
···
 		timeouts = nf_sctp_pernet(nf_ct_net(ct))->timeouts;
 
 	nf_ct_refresh_acct(ct, ctinfo, skb, timeouts[new_state]);
-
-	if (old_state == SCTP_CONNTRACK_COOKIE_ECHOED &&
-	    dir == IP_CT_DIR_REPLY &&
-	    new_state == SCTP_CONNTRACK_ESTABLISHED) {
-		pr_debug("Setting assured bit\n");
-		set_bit(IPS_ASSURED_BIT, &ct->status);
-		nf_conntrack_event_cache(IPCT_ASSURED, ct);
-	}
 
 	return NF_ACCEPT;
 

net/netfilter/nf_conntrack_standalone.c

···
 	NF_SYSCTL_CT_PROTO_TIMEOUT_SCTP_SHUTDOWN_RECD,
 	NF_SYSCTL_CT_PROTO_TIMEOUT_SCTP_SHUTDOWN_ACK_SENT,
 	NF_SYSCTL_CT_PROTO_TIMEOUT_SCTP_HEARTBEAT_SENT,
-	NF_SYSCTL_CT_PROTO_TIMEOUT_SCTP_HEARTBEAT_ACKED,
 #endif
 #ifdef CONFIG_NF_CT_PROTO_DCCP
 	NF_SYSCTL_CT_PROTO_TIMEOUT_DCCP_REQUEST,
···
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_jiffies,
 	},
-	[NF_SYSCTL_CT_PROTO_TIMEOUT_SCTP_HEARTBEAT_ACKED] = {
-		.procname       = "nf_conntrack_sctp_timeout_heartbeat_acked",
-		.maxlen         = sizeof(unsigned int),
-		.mode           = 0644,
-		.proc_handler   = proc_dointvec_jiffies,
-	},
 #endif
 #ifdef CONFIG_NF_CT_PROTO_DCCP
 	[NF_SYSCTL_CT_PROTO_TIMEOUT_DCCP_REQUEST] = {
···
 	XASSIGN(SHUTDOWN_RECD, sn);
 	XASSIGN(SHUTDOWN_ACK_SENT, sn);
 	XASSIGN(HEARTBEAT_SENT, sn);
-	XASSIGN(HEARTBEAT_ACKED, sn);
 #undef XASSIGN
 #endif
 }