afs: Fix the non-encryption of calls

Some AFS servers refuse to accept unencrypted traffic, so can't be accessed
with kAFS.  Set the AF_RXRPC security level to encrypt client calls to deal
with this.

Note that incoming service calls are set by the remote client and so aren't
affected by this.

This requires an AF_RXRPC patch to pass the value set by setsockopt to calls
begun by the kernel.
Signed-off-by: David Howells <dhowells@redhat.com>

fs/afs/rxrpc.c

@@ -41,6 +41,7 @@ int afs_open_socket(struct afs_net *net)
 {
 	struct sockaddr_rxrpc srx;
 	struct socket *socket;
+	unsigned int min_level;
 	int ret;
 
 	_enter("");
@@ -60,6 +61,12 @@ int afs_open_socket(struct afs_net *net)
 	srx.transport.sin6.sin6_family	= AF_INET6;
 	srx.transport.sin6.sin6_port	= htons(AFS_CM_PORT);
 
+	min_level = RXRPC_SECURITY_ENCRYPT;
+	ret = kernel_setsockopt(socket, SOL_RXRPC, RXRPC_MIN_SECURITY_LEVEL,
+				(void *)&min_level, sizeof(min_level));
+	if (ret < 0)
+		goto error_2;
+
 	ret = kernel_bind(socket, (struct sockaddr *) &srx, sizeof(srx));
 	if (ret == -EADDRINUSE) {
 		srx.transport.sin6.sin6_port = 0;