From 9c33e07143f5fc5de504b592724e392d9cc6f8a4 Mon Sep 17 00:00:00 2001
From: mvs <mvs@openbsd.org>
Date: Wed, 21 Aug 2024 07:36:12 +0000
Subject: [PATCH] Unlock ipip_sysctl().

- IPIPCTL_ALLOW - atomically accessed integer;
- IPIPCTL_STATS - per-CPU counters;

ok bluhm
---
 sys/netinet/in_proto.c |  4 ++--
 sys/netinet/ip_ipip.c  | 24 +++++++++++++-----------
 2 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/sys/netinet/in_proto.c b/sys/netinet/in_proto.c
index e4e00015ce9..9aefbd326a0 100644
--- a/sys/netinet/in_proto.c
+++ b/sys/netinet/in_proto.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: in_proto.c,v 1.110 2024/08/20 07:47:25 mvs Exp $	*/
+/*	$OpenBSD: in_proto.c,v 1.111 2024/08/21 07:36:12 mvs Exp $	*/
 /*	$NetBSD: in_proto.c,v 1.14 1996/02/18 18:58:32 christos Exp $	*/
 
 /*
@@ -230,7 +230,7 @@ const struct protosw inetsw[] = {
   .pr_type	= SOCK_RAW,
   .pr_domain	= &inetdomain,
   .pr_protocol	= IPPROTO_IPV4,
-  .pr_flags	= PR_ATOMIC|PR_ADDR|PR_MPSOCKET,
+  .pr_flags	= PR_ATOMIC|PR_ADDR|PR_MPSOCKET|PR_MPSYSCTL,
 #if NGIF > 0
   .pr_input	= in_gif_input,
 #else
diff --git a/sys/netinet/ip_ipip.c b/sys/netinet/ip_ipip.c
index fdebd088385..760eb8c9de9 100644
--- a/sys/netinet/ip_ipip.c
+++ b/sys/netinet/ip_ipip.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ip_ipip.c,v 1.102 2024/05/17 20:44:36 bluhm Exp $ */
+/*	$OpenBSD: ip_ipip.c,v 1.103 2024/08/21 07:36:12 mvs Exp $ */
 /*
  * The authors of this code are John Ioannidis (ji@tla.org),
  * Angelos D. Keromytis (kermit@csd.uch.gr) and
@@ -72,6 +72,11 @@
 #include <net/pfvar.h>
 #endif
 
+/*
+ * Locks used to protect data:
+ *	a	atomic
+ */
+
 #ifdef ENCDEBUG
 #define DPRINTF(fmt, args...)						\
 	do {								\
@@ -87,7 +92,7 @@
  * We can control the acceptance of IP4 packets by altering the sysctl
  * net.inet.ipip.allow value.  Zero means drop them, all else is acceptance.
  */
-int ipip_allow = 0;
+int ipip_allow = 0;	/* [a] */
 
 struct cpumem *ipipcounters;
 
@@ -106,7 +111,8 @@ ipip_input(struct mbuf **mp, int *offp, int nxt, int af)
 	struct ifnet *ifp;
 
 	/* If we do not accept IP-in-IP explicitly, drop.  */
-	if (!ipip_allow && ((*mp)->m_flags & (M_AUTH|M_CONF)) == 0) {
+	if (atomic_load_int(&ipip_allow) == 0 &&
+	    ((*mp)->m_flags & (M_AUTH|M_CONF)) == 0) {
 		DPRINTF("dropped due to policy");
 		ipipstat_inc(ipips_pdrops);
 		m_freemp(mp);
@@ -271,7 +277,8 @@ ipip_input_if(struct mbuf **mp, int *offp, int proto, int oaf,
 	}
 
 	/* Check for local address spoofing. */
-	if (!(ifp->if_flags & IFF_LOOPBACK) && ipip_allow != 2) {
+	if (!(ifp->if_flags & IFF_LOOPBACK) &&
+	    atomic_load_int(&ipip_allow) != 2) {
 		struct sockaddr_storage ss;
 		struct rtentry *rt;
 
@@ -584,19 +591,14 @@ int
 ipip_sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp, void *newp,
     size_t newlen)
 {
-	int error;
-
 	/* All sysctl names at this level are terminal. */
 	if (namelen != 1)
 		return (ENOTDIR);
 
 	switch (name[0]) {
 	case IPIPCTL_ALLOW:
-		NET_LOCK();
-		error = sysctl_int_bounded(oldp, oldlenp, newp, newlen,
-		    &ipip_allow, 0, 2);
-		NET_UNLOCK();
-		return (error);
+		return (sysctl_int_bounded(oldp, oldlenp, newp, newlen,
+		    &ipip_allow, 0, 2));
 	case IPIPCTL_STATS:
 		return (ipip_sysctl_ipipstat(oldp, oldlenp, newp));
 	default:
-- 
2.20.1