CIFS: Only send SMB2_NEGOTIATE command on new TCP connections

Do not allow commands other than SMB2_NEGOTIATE to be sent over
recently established TCP connections. Return -EAGAIN to let upper
layers handle it properly.

Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
diff --git a/fs/cifs/smb2transport.c b/fs/cifs/smb2transport.c
index fa1fec2..d118157 100644
--- a/fs/cifs/smb2transport.c
+++ b/fs/cifs/smb2transport.c
@@ -619,6 +619,10 @@
 		return -EAGAIN;
 	}
 
+	if (ses->server->tcpStatus == CifsNeedNegotiate &&
+	   shdr->Command != SMB2_NEGOTIATE)
+		return -EAGAIN;
+
 	if (ses->status == CifsNew) {
 		if ((shdr->Command != SMB2_SESSION_SETUP) &&
 		    (shdr->Command != SMB2_NEGOTIATE))
@@ -702,6 +706,10 @@
 			(struct smb2_sync_hdr *)rqst->rq_iov[0].iov_base;
 	struct mid_q_entry *mid;
 
+	if (server->tcpStatus == CifsNeedNegotiate &&
+	   shdr->Command != SMB2_NEGOTIATE)
+		return ERR_PTR(-EAGAIN);
+
 	smb2_seq_num_into_buf(server, shdr);
 
 	mid = smb2_mid_entry_alloc(shdr, server);