socket: Move SO_SETFIB handling to protocol layers

In particular, we store a FIB number in both struct socket and in struct
inpcb.  When updating the FIB number with setsockopt(SO_SETFIB), make
the update atomic.  This is required to support the new bind_all_fibs
mode, since in that mode changing the FIB of a bound socket is not
permitted.

This requires a bit more code, but avoids a layering violation in
sosetopt(), where we hard-code the list of protocol families that
implement SO_SETFIB.

Reviewed by:	glebius
MFC after:	2 weeks
Sponsored by:	Klara, Inc.
Sponsored by:	Stormshield
Differential Revision:	https://reviews.freebsd.org/D48666

1 files changed, 14 insertions, 15 deletions

diff --git a/sys/kern/uipc_socket.c b/sys/kern/uipc_socket.c
index c4ebb43eef18..65cea2e067cf 100644
--- a/sys/kern/uipc_socket.c
+++ b/sys/kern/uipc_socket.c
@@ -3699,6 +3699,19 @@ sorflush(struct socket *so)
 
 }
 
+int
+sosetfib(struct socket *so, int fibnum)
+{
+	if (fibnum < 0 || fibnum >= rt_numfibs)
+		return (EINVAL);
+
+	SOCK_LOCK(so);
+	so->so_fibnum = fibnum;
+	SOCK_UNLOCK(so);
+
+	return (0);
+}
+
 #ifdef SOCKET_HHOOK
 /*
  * Wrapper for Socket established helper hook.
@@ -3847,21 +3860,7 @@ sosetopt(struct socket *so, struct sockopt *sopt)
 			break;
 
 		case SO_SETFIB:
-			error = sooptcopyin(sopt, &optval, sizeof optval,
-			    sizeof optval);
-			if (error)
-				goto bad;
-
-			if (optval < 0 || optval >= rt_numfibs) {
-				error = EINVAL;
-				goto bad;
-			}
-			if (((so->so_proto->pr_domain->dom_family == PF_INET) ||
-			   (so->so_proto->pr_domain->dom_family == PF_INET6) ||
-			   (so->so_proto->pr_domain->dom_family == PF_ROUTE)))
-				so->so_fibnum = optval;
-			else
-				so->so_fibnum = 0;
+			error = so->so_proto->pr_ctloutput(so, sopt);
 			break;
 
 		case SO_USER_COOKIE: