Remove kernel lock from ifa_ifwithaddr() and ifa_ifwithdstaddr().

Netlock protects `if_list', `ifa_list' and returned `ifa' dereference,
so put netlock assertion within.

Please note, rtable_setsource() doesn't destroy data pointed by
`ar_source'. This is the `ifa_addr' data belongs to `ifa' and exclusive
netlock is required to destroy it. So the kernel lock is not required
within rt_setsource(). Take netlock by rt_setsource() caller to make
`ifa' dereference safe.

Suggestions and ok by bluhm@

1 files changed, 7 insertions, 12 deletions

diff --git a/sys/net/rtsock.c b/sys/net/rtsock.c
index b6d3c06894e..d3cc836db49 100644
--- a/sys/net/rtsock.c
+++ b/sys/net/rtsock.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rtsock.c,v 1.362 2023/04/18 09:56:54 mvs Exp $	*/
+/*	$OpenBSD: rtsock.c,v 1.363 2023/04/18 22:01:24 mvs Exp $	*/
 /*	$NetBSD: rtsock.c,v 1.18 1996/03/29 00:32:10 cgd Exp $	*/
 
 /*
@@ -853,8 +853,10 @@ route_output(struct mbuf *m, struct socket *so)
 			error = EINVAL;
 			goto fail;
 		}
-		if ((error =
-		    rt_setsource(tableid, info.rti_info[RTAX_IFA])) != 0)
+		NET_LOCK();
+		error = rt_setsource(tableid, info.rti_info[RTAX_IFA]);
+		NET_UNLOCK();
+		if (error)
 			goto fail;
 	} else {
 		error = rtm_output(rtm, &rt, &info, prio, tableid);
@@ -2350,7 +2352,6 @@ int
 rt_setsource(unsigned int rtableid, struct sockaddr *src)
 {
 	struct ifaddr	*ifa;
-	int		error;
 	/*
 	 * If source address is 0.0.0.0 or ::
 	 * use automatic source selection
@@ -2374,20 +2375,14 @@ rt_setsource(unsigned int rtableid, struct sockaddr *src)
 		return (EAFNOSUPPORT);
 	}
 
-	KERNEL_LOCK();
 	/*
 	 * Check if source address is assigned to an interface in the
 	 * same rdomain
 	 */
-	if ((ifa = ifa_ifwithaddr(src, rtableid)) == NULL) {
-		KERNEL_UNLOCK();
+	if ((ifa = ifa_ifwithaddr(src, rtableid)) == NULL)
 		return (EINVAL);
-	}
-
-	error = rtable_setsource(rtableid, src->sa_family, ifa->ifa_addr);
-	KERNEL_UNLOCK();
 
-	return (error);
+	return rtable_setsource(rtableid, src->sa_family, ifa->ifa_addr);
 }
 
 /*