svn commit: r353295 - head/sys/netinet6

[Mark Johnston]

Author: markj
Date: Mon Oct  7 23:35:23 2019
New Revision: 353295
URL: https://svnweb.freebsd.org/changeset/base/353295

Log:
  Improve locking in the IPV6_V6ONLY socket option handler.
  
  Acquire the inp lock before checking whether the socket is already bound,
  and around updates to the inp_vflag field.
  
  MFC after:	1 week
  Sponsored by:	The FreeBSD Foundation
  Differential Revision:	https://reviews.freebsd.org/D21867

Modified:
  head/sys/netinet6/ip6_output.c

Modified: head/sys/netinet6/ip6_output.c
==============================================================================
--- head/sys/netinet6/ip6_output.c	Mon Oct  7 23:31:17 2019	(r353294)
+++ head/sys/netinet6/ip6_output.c	Mon Oct  7 23:35:23 2019	(r353295)
@@ -1806,21 +1806,24 @@ do {									\
 #endif
 
 				case IPV6_V6ONLY:
-					/*
-					 * make setsockopt(IPV6_V6ONLY)
-					 * available only prior to bind(2).
-					 * see ipng mailing list, Jun 22 2001.
-					 */
+					INP_WLOCK(inp);
 					if (inp->inp_lport ||
 					    !IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr)) {
+						/*
+						 * The socket is already bound.
+						 */
+						INP_WUNLOCK(inp);
 						error = EINVAL;
 						break;
 					}
-					OPTSET(IN6P_IPV6_V6ONLY);
-					if (optval)
+					if (optval) {
+						inp->inp_flags |= IN6P_IPV6_V6ONLY;
 						inp->inp_vflag &= ~INP_IPV4;
-					else
+					} else {
+						inp->inp_flags &= ~IN6P_IPV6_V6ONLY;
 						inp->inp_vflag |= INP_IPV4;
+					}
+					INP_WUNLOCK(inp);
 					break;
 				case IPV6_RECVTCLASS:
 					/* cannot mix with RFC2292 XXX */