svn commit: r346755 - in stable/11: . share/man/man4 sys/netinet

Alexander Motin mav at FreeBSD.org
Fri Apr 26 17:01:58 UTC 2019 

Author: mav
Date: Fri Apr 26 17:01:56 2019
New Revision: 346755
URL: https://svnweb.freebsd.org/changeset/base/346755

Log:
  MFC r335837 (by kp): carp: Set DSCP value CS7
  
  Update carp to set DSCP value CS7(Network Traffic) in the flowlabel field of
  packets by default. Currently carp only sets TOS_LOWDELAY in IPv4 which was
  deprecated in 1998. This also implements sysctl that can revert carp back to
  it's old behavior if desired.
  
  This will allow implementation of QOS on modern network devices to make sure
  carp packets aren't dropped during interface contention.
  
  Submitted by:	Nick Wolff <darkfiberiru AT gmail.com>
  Sponsored by:	iXsystems, Inc.
  Differential Revision:	https://reviews.freebsd.org/D14536

Modified:
  stable/11/UPDATING
  stable/11/share/man/man4/carp.4
  stable/11/sys/netinet/ip.h
  stable/11/sys/netinet/ip6.h
  stable/11/sys/netinet/ip_carp.c
Directory Properties:
  stable/11/   (props changed)

Modified: stable/11/UPDATING
==============================================================================
--- stable/11/UPDATING	Fri Apr 26 16:38:23 2019	(r346754)
+++ stable/11/UPDATING	Fri Apr 26 17:01:56 2019	(r346755)
@@ -16,6 +16,12 @@ from older versions of FreeBSD, try WITHOUT_CLANG and 
 the tip of head, and then rebuild without this option. The bootstrap process
 from older version of current across the gcc/clang cutover is a bit fragile.
 
+20190426:
+	CARP now sets DSCP value CS7(Network Traffic) in the flowlabel field
+	of packets by default instead of only setting TOS_LOWDELAY in IPv4,
+	which was deprecated in 1998.  Original behavior can be restored by
+	setting sysctl net.inet.carp.dscp=4.
+
 20190416:
 	Clang, llvm, lld, lldb, compiler-rt and libc++ have been upgraded to
 	8.0.0.  Please see the 20141231 entry below for information about

Modified: stable/11/share/man/man4/carp.4
==============================================================================
--- stable/11/share/man/man4/carp.4	Fri Apr 26 16:38:23 2019	(r346754)
+++ stable/11/share/man/man4/carp.4	Fri Apr 26 17:01:56 2019	(r346755)
@@ -26,7 +26,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd February 21, 2013
+.Dd July 1, 2018
 .Dt CARP 4
 .Os
 .Sh NAME
@@ -102,6 +102,12 @@ Allow virtual hosts to preempt each other.
 When enabled, a vhid in a backup state would preempt a master that
 is announcing itself with a lower advskew.
 Disabled by default.
+.It Va net.inet.carp.dscp
+DSCP value in carp packet.
+Valid Values are 0 to 63.
+A value of 4 is equivalent to the old standard of TOS LOW_DELAY.
+TOS values were deprecated and replaced by DSCP in 1998.
+The default value is 56 (CS7/Network Control).
 .It Va net.inet.carp.log
 Determines what events relating to
 .Nm

Modified: stable/11/sys/netinet/ip.h
==============================================================================
--- stable/11/sys/netinet/ip.h	Fri Apr 26 16:38:23 2019	(r346754)
+++ stable/11/sys/netinet/ip.h	Fri Apr 26 17:01:56 2019	(r346755)
@@ -92,6 +92,11 @@ struct ip {
 #define	IPTOS_PREC_ROUTINE		IPTOS_DSCP_CS0
 
 /*
+ * Offset of Diffserv decimal value to convert it to tos value .
+ */
+#define	IPTOS_DSCP_OFFSET		2
+
+/*
  * Definitions for DiffServ Codepoints as per RFC2474 and RFC5865.
  */
 #define	IPTOS_DSCP_CS0		0x00

Modified: stable/11/sys/netinet/ip6.h
==============================================================================
--- stable/11/sys/netinet/ip6.h	Fri Apr 26 16:38:23 2019	(r346754)
+++ stable/11/sys/netinet/ip6.h	Fri Apr 26 17:01:56 2019	(r346755)
@@ -102,6 +102,7 @@ struct ip6_hdr {
 #define IPV6_FLOWLABEL_MASK	0xffff0f00	/* flow label (20 bits) */
 #endif /* LITTLE_ENDIAN */
 #endif
+#define IPV6_FLOWLABEL_LEN	20
 #if 1
 /* ECN bits proposed by Sally Floyd */
 #define IP6TOS_CE		0x01	/* congestion experienced */

Modified: stable/11/sys/netinet/ip_carp.c
==============================================================================
--- stable/11/sys/netinet/ip_carp.c	Fri Apr 26 16:38:23 2019	(r346754)
+++ stable/11/sys/netinet/ip_carp.c	Fri Apr 26 17:01:56 2019	(r346755)
@@ -190,6 +190,10 @@ static int proto_reg[] = {-1, -1};
 static VNET_DEFINE(int, carp_allow) = 1;
 #define	V_carp_allow	VNET(carp_allow)
 
+/* Set DSCP in outgoing CARP packets. */
+static VNET_DEFINE(int, carp_dscp) = 56;
+#define	V_carp_dscp	VNET(carp_dscp)
+
 /* Preempt slower nodes. */
 static VNET_DEFINE(int, carp_preempt) = 0;
 #define	V_carp_preempt	VNET(carp_preempt)
@@ -210,11 +214,15 @@ static VNET_DEFINE(int, carp_senderr_adj) = CARP_MAXSK
 static VNET_DEFINE(int, carp_ifdown_adj) = CARP_MAXSKEW;
 #define	V_carp_ifdown_adj	VNET(carp_ifdown_adj)
 
+static int carp_dscp_sysctl(SYSCTL_HANDLER_ARGS);
 static int carp_demote_adj_sysctl(SYSCTL_HANDLER_ARGS);
 
 SYSCTL_NODE(_net_inet, IPPROTO_CARP,	carp,	CTLFLAG_RW, 0,	"CARP");
 SYSCTL_INT(_net_inet_carp, OID_AUTO, allow, CTLFLAG_VNET | CTLFLAG_RW,
     &VNET_NAME(carp_allow), 0, "Accept incoming CARP packets");
+SYSCTL_PROC(_net_inet_carp, OID_AUTO, dscp,
+    CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW, 0, 0, carp_dscp_sysctl, "I",
+    "DSCP value for carp packets");
 SYSCTL_INT(_net_inet_carp, OID_AUTO, preempt, CTLFLAG_VNET | CTLFLAG_RW,
     &VNET_NAME(carp_preempt), 0, "High-priority backup preemption mode");
 SYSCTL_INT(_net_inet_carp, OID_AUTO, log, CTLFLAG_VNET | CTLFLAG_RW,
@@ -834,7 +842,7 @@ carp_send_ad_locked(struct carp_softc *sc)
 		ip = mtod(m, struct ip *);
 		ip->ip_v = IPVERSION;
 		ip->ip_hl = sizeof(*ip) >> 2;
-		ip->ip_tos = IPTOS_LOWDELAY;
+		ip->ip_tos = V_carp_dscp << IPTOS_DSCP_OFFSET;
 		ip->ip_len = htons(len);
 		ip->ip_off = htons(IP_DF);
 		ip->ip_ttl = CARP_DFLTTL;
@@ -886,6 +894,10 @@ carp_send_ad_locked(struct carp_softc *sc)
 		ip6 = mtod(m, struct ip6_hdr *);
 		bzero(ip6, sizeof(*ip6));
 		ip6->ip6_vfc |= IPV6_VERSION;
+		/* Traffic class isn't defined in ip6 struct instead
+		 * it gets offset into flowid field */
+		ip6->ip6_flow |= htonl(V_carp_dscp << (IPV6_FLOWLABEL_LEN +
+		    IPTOS_DSCP_OFFSET));
 		ip6->ip6_hlim = CARP_DFLTTL;
 		ip6->ip6_nxt = IPPROTO_CARP;
 		bzero(&sa, sizeof(sa));
@@ -2000,6 +2012,24 @@ carp_demote_adj(int adj, char *reason)
 	atomic_add_int(&V_carp_demotion, adj);
 	CARP_LOG("demoted by %d to %d (%s)\n", adj, V_carp_demotion, reason);
 	taskqueue_enqueue(taskqueue_swi, &carp_sendall_task);
+}
+
+static int
+carp_dscp_sysctl(SYSCTL_HANDLER_ARGS)
+{
+	int new, error;
+
+	new = V_carp_dscp;
+	error = sysctl_handle_int(oidp, &new, 0, req);
+	if (error || !req->newptr)
+		return (error);
+
+	if (new < 0 || new > 63)
+		return (EINVAL);
+
+	V_carp_dscp = new;
+
+	return (0);
 }
 
 static int

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