From ff1c038addc4f205d5f1ede449426c7d316c0eed Mon Sep 17 00:00:00 2001 From: Steve French Date: Tue, 19 Nov 2013 23:44:46 -0600 Subject: Check SMB3 dialects against downgrade attacks When we are running SMB3 or SMB3.02 connections which are signed we need to validate the protocol negotiation information, to ensure that the negotiate protocol response was not tampered with. Add the missing FSCTL which is sent at mount time (immediately after the SMB3 Tree Connect) to validate that the capabilities match what we think the server sent. "Secure dialect negotiation is introduced in SMB3 to protect against man-in-the-middle attempt to downgrade dialect negotiation. The idea is to prevent an eavesdropper from downgrading the initially negotiated dialect and capabilities between the client and the server." For more explanation see 2.2.31.4 of MS-SMB2 or http://blogs.msdn.com/b/openspecification/archive/2012/06/28/smb3-secure-dialect-negotiation.aspx Reviewed-by: Pavel Shilovsky Signed-off-by: Steve French --- fs/cifs/smb2ops.c | 1 + 1 file changed, 1 insertion(+) (limited to 'fs/cifs/smb2ops.c') diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c index a3968eeb6fac..757da3e54d3d 100644 --- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -1319,6 +1319,7 @@ struct smb_version_operations smb30_operations = { .create_lease_buf = smb3_create_lease_buf, .parse_lease_buf = smb3_parse_lease_buf, .clone_range = smb2_clone_range, + .validate_negotiate = smb3_validate_negotiate, }; struct smb_version_values smb20_values = { -- cgit v1.2.3