handshake: Fix sign of key_serial_t fields

key_serial_t fields are signed integers. Use nla_get/put_s32 for
those to avoid implicit signed conversion in the netlink protocol.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/169530167716.8905.645746457741372879.stgit@oracle-102.nfsv4bat.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/netlink/specs/handshake.yaml

@@ -34,10 +34,10 @@ attribute-sets:
     attributes:
       -
         name: cert
-        type: u32
+        type: s32
       -
         name: privkey
-        type: u32
+        type: s32
   -
     name: accept
     attributes:

net/handshake/tlshd.c

@@ -173,9 +173,9 @@ static int tls_handshake_put_certificate(struct sk_buff *msg,
 	if (!entry_attr)
 		return -EMSGSIZE;
 
-	if (nla_put_u32(msg, HANDSHAKE_A_X509_CERT,
+	if (nla_put_s32(msg, HANDSHAKE_A_X509_CERT,
 			treq->th_certificate) ||
-	    nla_put_u32(msg, HANDSHAKE_A_X509_PRIVKEY,
+	    nla_put_s32(msg, HANDSHAKE_A_X509_PRIVKEY,
 			treq->th_privkey)) {
 		nla_nest_cancel(msg, entry_attr);
 		return -EMSGSIZE;

tools/net/ynl/generated/handshake-user.h

@@ -28,8 +28,8 @@ struct handshake_x509 {
 		__u32 privkey:1;
 	} _present;
 
-	__u32 cert;
-	__u32 privkey;
+	__s32 cert;
+	__s32 privkey;
 };
 
 /* ============== HANDSHAKE_CMD_ACCEPT ============== */