[src/trunk]: src/sys Initialize DAD components properly

[ozaki-r <ozaki-r%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/d87c3ec75c2c
branches:  trunk
changeset: 459767:d87c3ec75c2c
user:      ozaki-r <ozaki-r%NetBSD.org@localhost>
date:      Wed Sep 25 09:52:32 2019 +0000

description:
Initialize DAD components properly

The original code initialized each component in non-init functions such as
arp_dad_start and nd6_dad_find, conditionally based on a global flag for each.
However, it was racy because the flag and the code around it were not
protected by a lock and could cause a kernel panic at worst.

Fix the issue by initializing the components in bootup as usual.

diffstat:

 sys/netinet/if_arp.c   |  25 +++++++++++++------------
 sys/netinet6/nd6.c     |   6 ++++--
 sys/netinet6/nd6.h     |   3 ++-
 sys/netinet6/nd6_nbr.c |  22 ++++++++++------------
 4 files changed, 29 insertions(+), 27 deletions(-)

diffs (180 lines):

diff -r c9fc4ca70bda -r d87c3ec75c2c sys/netinet/if_arp.c
--- a/sys/netinet/if_arp.c      Tue Sep 24 21:33:48 2019 +0000
+++ b/sys/netinet/if_arp.c      Wed Sep 25 09:52:32 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: if_arp.c,v 1.287 2019/09/01 22:09:02 roy Exp $ */
+/*     $NetBSD: if_arp.c,v 1.288 2019/09/25 09:52:32 ozaki-r Exp $     */
 
 /*
  * Copyright (c) 1998, 2000, 2008 The NetBSD Foundation, Inc.
@@ -68,7 +68,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_arp.c,v 1.287 2019/09/01 22:09:02 roy Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_arp.c,v 1.288 2019/09/25 09:52:32 ozaki-r Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_ddb.h"
@@ -153,6 +153,7 @@
 #endif
 
 static void arp_init(void);
+static void arp_dad_init(void);
 
 static void arprequest(struct ifnet *,
     const struct in_addr *, const struct in_addr *,
@@ -264,6 +265,8 @@
 #ifdef MBUFTRACE
        MOWNER_ATTACH(&arpdomain.dom_mowner);
 #endif
+
+       arp_dad_init();
 }
 
 static void
@@ -1510,10 +1513,17 @@
 };
 
 static struct dadq_head dadq;
-static int dad_init = 0;
 static int dad_maxtry = 15;     /* max # of *tries* to transmit DAD packet */
 static kmutex_t arp_dad_lock;
 
+static void
+arp_dad_init(void)
+{
+
+       TAILQ_INIT(&dadq);
+       mutex_init(&arp_dad_lock, MUTEX_DEFAULT, IPL_NONE);
+}
+
 static struct dadq *
 arp_dad_find(struct ifaddr *ifa)
 {
@@ -1588,12 +1598,6 @@
        struct dadq *dp;
        char ipbuf[INET_ADDRSTRLEN];
 
-       if (!dad_init) {
-               TAILQ_INIT(&dadq);
-               mutex_init(&arp_dad_lock, MUTEX_DEFAULT, IPL_NONE);
-               dad_init++;
-       }
-
        /*
         * If we don't need DAD, don't do it.
         * - DAD is disabled
@@ -1662,9 +1666,6 @@
 {
        struct dadq *dp;
 
-       if (!dad_init)
-               return;
-
        mutex_enter(&arp_dad_lock);
        dp = arp_dad_find(ifa);
        if (dp == NULL) {
diff -r c9fc4ca70bda -r d87c3ec75c2c sys/netinet6/nd6.c
--- a/sys/netinet6/nd6.c        Tue Sep 24 21:33:48 2019 +0000
+++ b/sys/netinet6/nd6.c        Wed Sep 25 09:52:32 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: nd6.c,v 1.263 2019/09/01 19:26:21 roy Exp $    */
+/*     $NetBSD: nd6.c,v 1.264 2019/09/25 09:52:32 ozaki-r Exp $        */
 /*     $KAME: nd6.c,v 1.279 2002/06/08 11:16:51 itojun Exp $   */
 
 /*
@@ -31,7 +31,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: nd6.c,v 1.263 2019/09/01 19:26:21 roy Exp $");
+__KERNEL_RCSID(0, "$NetBSD: nd6.c,v 1.264 2019/09/25 09:52:32 ozaki-r Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_net_mpsafe.h"
@@ -137,6 +137,8 @@
 {
        int error;
 
+       nd6_nbr_init();
+
        rw_init(&nd6_lock);
 
        /* initialization of the default router list */
diff -r c9fc4ca70bda -r d87c3ec75c2c sys/netinet6/nd6.h
--- a/sys/netinet6/nd6.h        Tue Sep 24 21:33:48 2019 +0000
+++ b/sys/netinet6/nd6.h        Wed Sep 25 09:52:32 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: nd6.h,v 1.87 2019/09/01 19:26:21 roy Exp $     */
+/*     $NetBSD: nd6.h,v 1.88 2019/09/25 09:52:32 ozaki-r Exp $ */
 /*     $KAME: nd6.h,v 1.95 2002/06/08 11:31:06 itojun Exp $    */
 
 /*
@@ -430,6 +430,7 @@
 /* XXX: need nd6_var.h?? */
 /* nd6.c */
 void nd6_init(void);
+void nd6_nbr_init(void);
 struct nd_ifinfo *nd6_ifattach(struct ifnet *);
 void nd6_ifdetach(struct ifnet *, struct in6_ifextra *);
 int nd6_is_addr_neighbor(const struct sockaddr_in6 *, struct ifnet *);
diff -r c9fc4ca70bda -r d87c3ec75c2c sys/netinet6/nd6_nbr.c
--- a/sys/netinet6/nd6_nbr.c    Tue Sep 24 21:33:48 2019 +0000
+++ b/sys/netinet6/nd6_nbr.c    Wed Sep 25 09:52:32 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: nd6_nbr.c,v 1.173 2019/09/18 08:18:05 ozaki-r Exp $    */
+/*     $NetBSD: nd6_nbr.c,v 1.174 2019/09/25 09:52:32 ozaki-r Exp $    */
 /*     $KAME: nd6_nbr.c,v 1.61 2001/02/10 16:06:14 jinmei Exp $        */
 
 /*
@@ -31,7 +31,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: nd6_nbr.c,v 1.173 2019/09/18 08:18:05 ozaki-r Exp $");
+__KERNEL_RCSID(0, "$NetBSD: nd6_nbr.c,v 1.174 2019/09/25 09:52:32 ozaki-r Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_inet.h"
@@ -1124,9 +1124,16 @@
 };
 
 static struct dadq_head dadq;
-static int dad_init = 0;
 static kmutex_t nd6_dad_lock;
 
+void
+nd6_nbr_init(void)
+{
+
+       TAILQ_INIT(&dadq);
+       mutex_init(&nd6_dad_lock, MUTEX_DEFAULT, IPL_NONE);
+}
+
 static struct dadq *
 nd6_dad_find(struct ifaddr *ifa, struct nd_opt_nonce *nonce, bool *found_nonce)
 {
@@ -1238,12 +1245,6 @@
        struct dadq *dp;
        char ip6buf[INET6_ADDRSTRLEN];
 
-       if (!dad_init) {
-               TAILQ_INIT(&dadq);
-               mutex_init(&nd6_dad_lock, MUTEX_DEFAULT, IPL_NONE);
-               dad_init++;
-       }
-
        /*
         * If we don't need DAD, don't do it.
         * There are several cases:
@@ -1321,9 +1322,6 @@
 {
        struct dadq *dp;
 
-       if (!dad_init)
-               return;
-
        mutex_enter(&nd6_dad_lock);
        dp = nd6_dad_find(ifa, NULL, NULL);
        if (dp == NULL) {