rxrpc: add rxrpc_sock_set_min_security_level

Add a helper to directly set the RXRPC_MIN_SECURITY_LEVEL sockopt from
kernel space without going through a fake uaccess.

Thanks to David Howells for the documentation updates.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/Documentation/networking/rxrpc.rst b/Documentation/networking/rxrpc.rst
index 5ad3511..68552b9 100644
--- a/Documentation/networking/rxrpc.rst
+++ b/Documentation/networking/rxrpc.rst
@@ -477,7 +477,7 @@
 	 Encrypted checksum plus packet padded and first eight bytes of packet
 	 encrypted - which includes the actual packet length.
 
-     (c) RXRPC_SECURITY_ENCRYPTED
+     (c) RXRPC_SECURITY_ENCRYPT
 
 	 Encrypted checksum plus entire packet padded and encrypted, including
 	 actual packet length.
@@ -578,7 +578,7 @@
      This issues a request_key() to get the key representing the security
      context.  The minimum security level can be set::
 
-	unsigned int sec = RXRPC_SECURITY_ENCRYPTED;
+	unsigned int sec = RXRPC_SECURITY_ENCRYPT;
 	setsockopt(client, SOL_RXRPC, RXRPC_MIN_SECURITY_LEVEL,
 		   &sec, sizeof(sec));
 
@@ -1090,6 +1090,15 @@
      jiffies).  In the event of the timeout occurring, the call will be
      aborted and -ETIME or -ETIMEDOUT will be returned.
 
+ (#) Apply the RXRPC_MIN_SECURITY_LEVEL sockopt to a socket from within in the
+     kernel::
+
+       int rxrpc_sock_set_min_security_level(struct sock *sk,
+					     unsigned int val);
+
+     This specifies the minimum security level required for calls on this
+     socket.
+
 
 Configurable Parameters
 =======================