tls: always set record_type in tls_process_cmsg

When userspace wants to send a non-DATA record (via the
TLS_SET_RECORD_TYPE cmsg), we need to send any pending data from a
previous MSG_MORE send() as a separate DATA record. If that DATA record
is encrypted asynchronously, tls_handle_open_record will return
-EINPROGRESS. This is currently treated as an error by
tls_process_cmsg, and it will skip setting record_type to the correct
value, but the caller (tls_sw_sendmsg_locked) handles that return
value correctly and proceeds with sending the new message with an
incorrect record_type (DATA instead of whatever was requested in the
cmsg).

Always set record_type before handling the open record. If
tls_handle_open_record returns an error, record_type will be
ignored. If it succeeds, whether with synchronous crypto (returning 0)
or asynchronous (returning -EINPROGRESS), the caller will proceed
correctly.

Fixes: a42055e ("net/tls: Add support for async encryption of records for performance")
Reported-by: Jann Horn <[email protected]>
Signed-off-by: Sabrina Dubroca <[email protected]>
Link: https://patch.msgid.link/0457252e578a10a94e40c72ba6288b3a64f31662.1760432043.git.sd@queasysnail.net
Signed-off-by: Jakub Kicinski <[email protected]>

Author: qsn

net/tls/tls_main.c

@@ -255,12 +255,9 @@ int tls_process_cmsg(struct sock *sk, struct msghdr *msg,
 			if (msg->msg_flags & MSG_MORE)
 				return -EINVAL;
 
-			rc = tls_handle_open_record(sk, msg->msg_flags);
-			if (rc)
-				return rc;
-
 			*record_type = *(unsigned char *)CMSG_DATA(cmsg);
-			rc = 0;
+
+			rc = tls_handle_open_record(sk, msg->msg_flags);
 			break;
 		default:
 			return -EINVAL;