git: cc3793b1c548 - main - netlink: improve source ifa selection algorithm when adding routes.

The branch main has been updated by melifaro:

URL: https://cgit.FreeBSD.org/src/commit/?id=cc3793b1c54847e26001f42026778703970fa570

commit cc3793b1c54847e26001f42026778703970fa570
Author:     Alexander V. Chernikov <melifaro@FreeBSD.org>
AuthorDate: 2023-04-09 13:30:45 +0000
Commit:     Alexander V. Chernikov <melifaro@FreeBSD.org>
CommitDate: 2023-04-09 13:33:22 +0000

    netlink: improve source ifa selection algorithm when adding routes.
    
    Use route destination sockaddr when the gateway is eiter AF_LINK or
     has the different family (IPv4 over IPv6). This change ensures
     the nexthop IFA has the same family as the destination.
    
    Reported by:    Dmitriy Smirnov <fox@sage.su>
    Tested by:      Dmitriy Smirnov <fox@sage.su>
    MFC after:      3 days
---
 sys/netlink/route/rt.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/sys/netlink/route/rt.c b/sys/netlink/route/rt.c
index 7e81d59d696b..db535cb676e4 100644
--- a/sys/netlink/route/rt.c
+++ b/sys/netlink/route/rt.c
@@ -708,7 +708,19 @@ finalize_nhop(struct nhop_object *nh, const struct sockaddr *dst, int *perror)
 	}
 	/* Both nh_ifp and gateway are set */
 	if (nh->nh_ifa == NULL) {
-		struct ifaddr *ifa = ifaof_ifpforaddr(&nh->gw_sa, nh->nh_ifp);
+		const struct sockaddr *gw_sa = &nh->gw_sa;
+
+		if (gw_sa->sa_family != dst->sa_family) {
+			/*
+			 * Use dst as the target for determining the default
+			 * preferred ifa IF
+			 * 1) the gateway is link-level (e.g. direct route)
+			 * 2) the gateway family is different (e.g. IPv4 over IPv6).
+			 */
+			gw_sa = dst;
+		}
+
+		struct ifaddr *ifa = ifaof_ifpforaddr(gw_sa, nh->nh_ifp);
 		if (ifa == NULL) {
 			NL_LOG(LOG_DEBUG, "Unable to determine ifa, skipping");
 			*perror = EINVAL;