net/tls: handle MSG_EOR for tls_sw TX flow

tls_sw_sendmsg() already handles MSG_MORE, but bails
out on MSG_EOR.
Seeing that MSG_EOR is basically the opposite of
MSG_MORE this patch adds handling MSG_EOR by treating
it as the negation of MSG_MORE.
And erroring out if MSG_EOR is specified with MSG_MORE.
Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20230726191556.41714-2-hare@suse.deSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/tls/tls_sw.c

@@ -984,6 +984,9 @@ static int tls_sw_sendmsg_locked(struct sock *sk, struct msghdr *msg,
 	int ret = 0;
 	int pending;
 
+	if (!eor && (msg->msg_flags & MSG_EOR))
+		return -EINVAL;
+
 	if (unlikely(msg->msg_controllen)) {
 		ret = tls_process_cmsg(sk, msg, &record_type);
 		if (ret) {
@@ -1193,7 +1196,7 @@ int tls_sw_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
 	int ret;
 
 	if (msg->msg_flags & ~(MSG_MORE | MSG_DONTWAIT | MSG_NOSIGNAL |
-			       MSG_CMSG_COMPAT | MSG_SPLICE_PAGES |
+			       MSG_CMSG_COMPAT | MSG_SPLICE_PAGES | MSG_EOR |
 			       MSG_SENDPAGE_NOPOLICY))
 		return -EOPNOTSUPP;