linux-kernel - [PATCH 4.19 004/116] cifs: set server->cipher

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Date:   Mon, 31 May 2021 15:13:00 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Aurelien Aptel <aaptel@...e.com>,
        Steve French <stfrench@...rosoft.com>
Subject: [PATCH 4.19 004/116] cifs: set server->cipher_type to AES-128-CCM for SMB3.0

From: Aurelien Aptel <aaptel@...e.com>

commit 6d2fcfe6b517fe7cbf2687adfb0a16cdcd5d9243 upstream.

SMB3.0 doesn't have encryption negotiate context but simply uses
the SMB2_GLOBAL_CAP_ENCRYPTION flag.

When that flag is present in the neg response cifs.ko uses AES-128-CCM
which is the only cipher available in this context.

cipher_type was set to the server cipher only when parsing encryption
negotiate context (SMB3.1.1).

For SMB3.0 it was set to 0. This means cipher_type value can be 0 or 1
for AES-128-CCM.

Fix this by checking for SMB3.0 and encryption capability and setting
cipher_type appropriately.

Signed-off-by: Aurelien Aptel <aaptel@...e.com>
Cc: <stable@...r.kernel.org>
Signed-off-by: Steve French <stfrench@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/cifs/smb2pdu.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -791,6 +791,13 @@ SMB2_negotiate(const unsigned int xid, s
 	/* Internal types */
 	server->capabilities |= SMB2_NT_FIND | SMB2_LARGE_FILES;

+	/*
+	 * SMB3.0 supports only 1 cipher and doesn't have a encryption neg context
+	 * Set the cipher type manually.
+	 */
+	if (server->dialect == SMB30_PROT_ID && (server->capabilities & SMB2_GLOBAL_CAP_ENCRYPTION))
+		server->cipher_type = SMB2_ENCRYPTION_AES128_CCM;
+
 	security_blob = smb2_get_data_area_len(&blob_offset, &blob_length,
 					       (struct smb2_sync_hdr *)rsp);
 	/*