Merge branch 'sctp-rfc7829'

Xin Long says:

====================
sctp: update from rfc7829

SCTP-PF was implemented based on a Internet-Draft in 2012:

  https://tools.ietf.org/html/draft-nishida-tsvwg-sctp-failover-05

It's been updated quite a few by rfc7829 in 2016.

This patchset adds the following features:

  1. add SCTP_ADDR_POTENTIALLY_FAILED notification
  2. add pf_expose per netns/sock/asoc
  3. add SCTP_EXPOSE_POTENTIALLY_FAILED_STATE sockopt
  4. add ps_retrans per netns/sock/asoc/transport
     (Primary Path Switchover)
  5. add spt_pathcpthld for SCTP_PEER_ADDR_THLDS sockopt

v1->v2:
  - See Patch 2/5 and Patch 5/5.
v2->v3:
  - See Patch 1/5, 2/5 and 3/5.
v3->v4:
  - See Patch 1/5, 2/5, 3/5 and 4/5.
====================

Signed-off-by: David S. Miller <[email protected]>

Documentation/networking/ip-sysctl.txt

@@ -2091,6 +2091,28 @@ pf_enable - INTEGER
 
 	Default: 1
 
+pf_expose - INTEGER
+	Unset or enable/disable pf (pf is short for potentially failed) state
+	exposure.  Applications can control the exposure of the PF path state
+	in the SCTP_PEER_ADDR_CHANGE event and the SCTP_GET_PEER_ADDR_INFO
+	sockopt.   When it's unset, no SCTP_PEER_ADDR_CHANGE event with
+	SCTP_ADDR_PF state will be sent and a SCTP_PF-state transport info
+	can be got via SCTP_GET_PEER_ADDR_INFO sockopt;  When it's enabled,
+	a SCTP_PEER_ADDR_CHANGE event will be sent for a transport becoming
+	SCTP_PF state and a SCTP_PF-state transport info can be got via
+	SCTP_GET_PEER_ADDR_INFO sockopt;  When it's diabled, no
+	SCTP_PEER_ADDR_CHANGE event will be sent and it returns -EACCES when
+	trying to get a SCTP_PF-state transport info via SCTP_GET_PEER_ADDR_INFO
+	sockopt.
+
+	0: Unset pf state exposure, Compatible with old applications.
+
+	1: Disable pf state exposure.
+
+	2: Enable pf state exposure.
+
+	Default: 0
+
 addip_noauth_enable - BOOLEAN
 	Dynamic Address Reconfiguration (ADD-IP) requires the use of
 	authentication to protect the operations of adding or removing new
@@ -2173,6 +2195,18 @@ pf_retrans - INTEGER
 
 	Default: 0
 
+ps_retrans - INTEGER
+	Primary.Switchover.Max.Retrans (PSMR), it's a tunable parameter coming
+	from section-5 "Primary Path Switchover" in rfc7829.  The primary path
+	will be changed to another active path when the path error counter on
+	the old primary path exceeds PSMR, so that "the SCTP sender is allowed
+	to continue data transmission on a new working path even when the old
+	primary destination address becomes active again".   Note this feature
+	is disabled by initializing 'ps_retrans' per netns as 0xffff by default,
+	and its value can't be less than 'pf_retrans' when changing by sysctl.
+
+	Default: 0xffff
+
 rto_initial - INTEGER
 	The initial round trip timeout value in milliseconds that will be used
 	in calculating round trip times.  This is the initial time interval

include/net/netns/sctp.h

@@ -89,13 +89,27 @@ struct netns_sctp {
 	 */
 	int pf_retrans;
 
+	/* Primary.Switchover.Max.Retrans sysctl value
+	 * taken from:
+	 * https://tools.ietf.org/html/rfc7829
+	 */
+	int ps_retrans;
+
 	/*
 	 * Disable Potentially-Failed feature, the feature is enabled by default
 	 * pf_enable	-  0  : disable pf
 	 *		- >0  : enable pf
 	 */
 	int pf_enable;
 
+	/*
+	 * Disable Potentially-Failed state exposure, ignored by default
+	 * pf_expose	-  0  : compatible with old applications (by default)
+	 *		-  1  : disable pf state exposure
+	 *		-  2  : enable  pf state exposure
+	 */
+	int pf_expose;
+
 	/*
 	 * Policy for preforming sctp/socket accounting
 	 * 0   - do socket level accounting, all assocs share sk_sndbuf

include/net/sctp/constants.h

@@ -286,6 +286,18 @@ enum { SCTP_MAX_GABS = 16 };
 				 * functions simpler to write.
 				 */
 
+/* These are the values for pf exposure, UNUSED is to keep compatible with old
+ * applications by default.
+ */
+enum {
+	SCTP_PF_EXPOSE_UNSET,
+	SCTP_PF_EXPOSE_DISABLE,
+	SCTP_PF_EXPOSE_ENABLE,
+};
+#define SCTP_PF_EXPOSE_MAX	SCTP_PF_EXPOSE_ENABLE
+
+#define SCTP_PS_RETRANS_MAX	0xffff
+
 /* These return values describe the success or failure of a number of
  * routines which form the lower interface to SCTP_outqueue.
  */

include/net/sctp/structs.h

@@ -184,7 +184,8 @@ struct sctp_sock {
 	__u32 flowlabel;
 	__u8  dscp;
 
-	int pf_retrans;
+	__u16 pf_retrans;
+	__u16 ps_retrans;
 
 	/* The initial Path MTU to use for new associations. */
 	__u32 pathmtu;
@@ -215,6 +216,7 @@ struct sctp_sock {
 	__u32 adaptation_ind;
 	__u32 pd_point;
 	__u16	nodelay:1,
+		pf_expose:2,
 		reuse:1,
 		disable_fragments:1,
 		v4mapped:1,
@@ -896,7 +898,9 @@ struct sctp_transport {
 	 * and will be initialized from the assocs value.  This can be changed
 	 * using the SCTP_PEER_ADDR_THLDS socket option
 	 */
-	int pf_retrans;
+	__u16 pf_retrans;
+	/* Used for primary path switchover. */
+	__u16 ps_retrans;
 	/* PMTU	      : The current known path MTU.  */
 	__u32 pathmtu;
 
@@ -1772,7 +1776,9 @@ struct sctp_association {
 	 * and will be initialized from the assocs value.  This can be
 	 * changed using the SCTP_PEER_ADDR_THLDS socket option
 	 */
-	int pf_retrans;
+	__u16 pf_retrans;
+	/* Used for primary path switchover. */
+	__u16 ps_retrans;
 
 	/* Maximum number of times the endpoint will retransmit INIT  */
 	__u16 max_init_attempts;
@@ -2053,6 +2059,7 @@ struct sctp_association {
 
 	__u8 need_ecne:1,	/* Need to send an ECNE Chunk? */
 	     temp:1,		/* Is it a temporary association? */
+	     pf_expose:2,       /* Expose pf state? */
 	     force_delay:1;
 
 	__u8 strreset_enable;

include/uapi/linux/sctp.h

@@ -105,6 +105,7 @@ typedef __s32 sctp_assoc_t;
 #define SCTP_DEFAULT_SNDINFO	34
 #define SCTP_AUTH_DEACTIVATE_KEY	35
 #define SCTP_REUSE_PORT		36
+#define SCTP_PEER_ADDR_THLDS_V2	37
 
 /* Internal Socket Options. Some of the sctp library functions are
  * implemented using these socket options.
@@ -137,6 +138,8 @@ typedef __s32 sctp_assoc_t;
 #define SCTP_ASCONF_SUPPORTED	128
 #define SCTP_AUTH_SUPPORTED	129
 #define SCTP_ECN_SUPPORTED	130
+#define SCTP_EXPOSE_POTENTIALLY_FAILED_STATE	131
+#define SCTP_EXPOSE_PF_STATE	SCTP_EXPOSE_POTENTIALLY_FAILED_STATE
 
 /* PR-SCTP policies */
 #define SCTP_PR_SCTP_NONE	0x0000
@@ -410,6 +413,8 @@ enum sctp_spc_state {
 	SCTP_ADDR_ADDED,
 	SCTP_ADDR_MADE_PRIM,
 	SCTP_ADDR_CONFIRMED,
+	SCTP_ADDR_POTENTIALLY_FAILED,
+#define SCTP_ADDR_PF	SCTP_ADDR_POTENTIALLY_FAILED
 };
 
 
@@ -933,6 +938,7 @@ struct sctp_paddrinfo {
 enum sctp_spinfo_state {
 	SCTP_INACTIVE,
 	SCTP_PF,
+#define	SCTP_POTENTIALLY_FAILED		SCTP_PF
 	SCTP_ACTIVE,
 	SCTP_UNCONFIRMED,
 	SCTP_UNKNOWN = 0xffff  /* Value used for transport state unknown */
@@ -1082,6 +1088,15 @@ struct sctp_paddrthlds {
 	__u16 spt_pathpfthld;
 };
 
+/* Use a new structure with spt_pathcpthld for back compatibility */
+struct sctp_paddrthlds_v2 {
+	sctp_assoc_t spt_assoc_id;
+	struct sockaddr_storage spt_address;
+	__u16 spt_pathmaxrxt;
+	__u16 spt_pathpfthld;
+	__u16 spt_pathcpthld;
+};
+
 /*
  * Socket Option for Getting the Association/Stream-Specific PR-SCTP Status
  */

net/sctp/associola.c

@@ -86,6 +86,8 @@ static struct sctp_association *sctp_association_init(
 	 */
 	asoc->max_retrans = sp->assocparams.sasoc_asocmaxrxt;
 	asoc->pf_retrans  = sp->pf_retrans;
+	asoc->ps_retrans  = sp->ps_retrans;
+	asoc->pf_expose   = sp->pf_expose;
 
 	asoc->rto_initial = msecs_to_jiffies(sp->rtoinfo.srto_initial);
 	asoc->rto_max = msecs_to_jiffies(sp->rtoinfo.srto_max);
@@ -627,6 +629,8 @@ struct sctp_transport *sctp_assoc_add_peer(struct sctp_association *asoc,
 
 	/* And the partial failure retrans threshold */
 	peer->pf_retrans = asoc->pf_retrans;
+	/* And the primary path switchover retrans threshold */
+	peer->ps_retrans = asoc->ps_retrans;
 
 	/* Initialize the peer's SACK delay timeout based on the
 	 * association configured value.
@@ -786,8 +790,8 @@ void sctp_assoc_control_transport(struct sctp_association *asoc,
 				  enum sctp_transport_cmd command,
 				  sctp_sn_error_t error)
 {
+	int spc_state = SCTP_ADDR_AVAILABLE;
 	bool ulp_notify = true;
-	int spc_state = 0;
 
 	/* Record the transition on the transport.  */
 	switch (command) {
@@ -796,19 +800,13 @@ void sctp_assoc_control_transport(struct sctp_association *asoc,
 		 * to heartbeat success, report the SCTP_ADDR_CONFIRMED
 		 * state to the user, otherwise report SCTP_ADDR_AVAILABLE.
 		 */
-		if (SCTP_UNCONFIRMED == transport->state &&
-		    SCTP_HEARTBEAT_SUCCESS == error)
-			spc_state = SCTP_ADDR_CONFIRMED;
-		else
-			spc_state = SCTP_ADDR_AVAILABLE;
-		/* Don't inform ULP about transition from PF to
-		 * active state and set cwnd to 1 MTU, see SCTP
-		 * Quick failover draft section 5.1, point 5
-		 */
-		if (transport->state == SCTP_PF) {
+		if (transport->state == SCTP_PF &&
+		    asoc->pf_expose != SCTP_PF_EXPOSE_ENABLE)
 			ulp_notify = false;
-			transport->cwnd = asoc->pathmtu;
-		}
+		else if (transport->state == SCTP_UNCONFIRMED &&
+			 error == SCTP_HEARTBEAT_SUCCESS)
+			spc_state = SCTP_ADDR_CONFIRMED;
+
 		transport->state = SCTP_ACTIVE;
 		break;
 
@@ -817,19 +815,21 @@ void sctp_assoc_control_transport(struct sctp_association *asoc,
 		 * to inactive state.  Also, release the cached route since
 		 * there may be a better route next time.
 		 */
-		if (transport->state != SCTP_UNCONFIRMED)
+		if (transport->state != SCTP_UNCONFIRMED) {
 			transport->state = SCTP_INACTIVE;
-		else {
+			spc_state = SCTP_ADDR_UNREACHABLE;
+		} else {
 			sctp_transport_dst_release(transport);
 			ulp_notify = false;
 		}
-
-		spc_state = SCTP_ADDR_UNREACHABLE;
 		break;
 
 	case SCTP_TRANSPORT_PF:
 		transport->state = SCTP_PF;
-		ulp_notify = false;
+		if (asoc->pf_expose != SCTP_PF_EXPOSE_ENABLE)
+			ulp_notify = false;
+		else
+			spc_state = SCTP_ADDR_POTENTIALLY_FAILED;
 		break;
 
 	default:

net/sctp/protocol.c

@@ -1217,9 +1217,15 @@ static int __net_init sctp_defaults_init(struct net *net)
 	/* Max.Burst		    - 4 */
 	net->sctp.max_burst			= SCTP_DEFAULT_MAX_BURST;
 
+	/* Disable of Primary Path Switchover by default */
+	net->sctp.ps_retrans = SCTP_PS_RETRANS_MAX;
+
 	/* Enable pf state by default */
 	net->sctp.pf_enable = 1;
 
+	/* Ignore pf exposure feature by default */
+	net->sctp.pf_expose = SCTP_PF_EXPOSE_UNSET;
+
 	/* Association.Max.Retrans  - 10 attempts
 	 * Path.Max.Retrans         - 5  attempts (per destination address)
 	 * Max.Init.Retransmits     - 8  attempts

net/sctp/sm_sideeffect.c

@@ -567,6 +567,11 @@ static void sctp_do_8_2_transport_strike(struct sctp_cmd_seq *commands,
 					     SCTP_FAILED_THRESHOLD);
 	}
 
+	if (transport->error_count > transport->ps_retrans &&
+	    asoc->peer.primary_path == transport &&
+	    asoc->peer.active_path != transport)
+		sctp_assoc_set_primary(asoc, asoc->peer.active_path);
+
 	/* E2) For the destination address for which the timer
 	 * expires, set RTO <- RTO * 2 ("back off the timer").  The
 	 * maximum value discussed in rule C7 above (RTO.max) may be