cifs: don't start signing too early

Sniffing traffic on the wire shows that windows clients send a zeroed out signature field in a NEGOTIATE request, and send "BSRSPYL" in the signature field during SESSION_SETUP. Make the cifs client behave the same way. It doesn't seem to make much difference in any server that I've tested against, but it's probably best to follow windows behavior as closely as possible here. Signed-off-by: Jeff Layton <[email protected]> Reviewed-by: Shirish Pargaonkar <[email protected]> Signed-off-by: Steve French <[email protected]>
paperplane · Jul 31, 2011 · 998d6fc · 998d6fc
1 parent 1f1cff0
commit 998d6fc
Showing 1 changed file with 14 additions and 2 deletions.
diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
@@ -87,9 +87,15 @@ int cifs_sign_smb(struct smb_hdr *cifs_pdu, struct TCP_Server_Info *server,
 	if ((cifs_pdu == NULL) || (server == NULL))
 		return -EINVAL;
 
-	if ((cifs_pdu->Flags2 & SMBFLG2_SECURITY_SIGNATURE) == 0)
+	if (!(cifs_pdu->Flags2 & SMBFLG2_SECURITY_SIGNATURE) ||
+	    server->tcpStatus == CifsNeedNegotiate)
 		return rc;
 
+	if (!server->session_estab) {
+		strncpy(cifs_pdu->Signature.SecuritySignature, "BSRSPYL", 8);
+		return rc;
+	}
+
 	cifs_pdu->Signature.Sequence.SequenceNumber =
 			cpu_to_le32(server->sequence_number);
 	cifs_pdu->Signature.Sequence.Reserved = 0;
@@ -178,9 +184,15 @@ int cifs_sign_smb2(struct kvec *iov, int n_vec, struct TCP_Server_Info *server,
 	if ((cifs_pdu == NULL) || (server == NULL))
 		return -EINVAL;
 
-	if ((cifs_pdu->Flags2 & SMBFLG2_SECURITY_SIGNATURE) == 0)
+	if (!(cifs_pdu->Flags2 & SMBFLG2_SECURITY_SIGNATURE) ||
+	    server->tcpStatus == CifsNeedNegotiate)
 		return rc;
 
+	if (!server->session_estab) {
+		strncpy(cifs_pdu->Signature.SecuritySignature, "BSRSPYL", 8);
+		return rc;
+	}
+
 	cifs_pdu->Signature.Sequence.SequenceNumber =
 				cpu_to_le32(server->sequence_number);
 	cifs_pdu->Signature.Sequence.Reserved = 0;