Re: [PATCH 4.13 28/43] SMB3: Validate negotiate request must always be signed

[Greg Kroah-Hartman]

On Tue, Oct 31, 2017 at 03:02:11PM +0200, Thomas Backlund wrote:
> Den 31.10.2017 kl. 11:55, skrev Greg Kroah-Hartman:
> > 4.13-stable review patch.  If anyone has any objections, please let me know.
> > 
> > ------------------
> > 
> > From: Steve French <smfrench@xxxxxxxxx>
> > 
> > commit 4587eee04e2ac7ac3ac9fa2bc164fb6e548f99cd upstream.
> > 
> > According to MS-SMB2 3.2.55 validate_negotiate request must
> > always be signed. Some Windows can fail the request if you send it unsigned
> > 
> > See kernel bugzilla bug 197311
> > 
> > Acked-by: Ronnie Sahlberg <lsahlber.redhat.com>
> > Signed-off-by: Steve French <smfrench@xxxxxxxxx>
> > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > 
> > ---
> >   fs/cifs/smb2pdu.c |    3 +++
> >   1 file changed, 3 insertions(+)
> > 
> > --- a/fs/cifs/smb2pdu.c
> > +++ b/fs/cifs/smb2pdu.c
> > @@ -1963,6 +1963,9 @@ SMB2_ioctl(const unsigned int xid, struc
> >   	} else
> >   		iov[0].iov_len = get_rfc1002_length(req) + 4;
> > +	/* validate negotiate request must be signed - see MS-SMB2 3.2.5.5 */
> > +	if (opcode == FSCTL_VALIDATE_NEGOTIATE_INFO)
> > +		req->hdr.sync_hdr.Flags |= SMB2_FLAGS_SIGNED;
> >   	rc = SendReceive2(xid, ses, iov, n_iov, &resp_buftype, flags, &rsp_iov);
> >   	cifs_small_buf_release(req);
> > 
> > 
> > 
> 
> This one needs to be backported to all stable kernels as the commit that
> introduced the regression:
> '
> 0603c96f3af50e2f9299fa410c224ab1d465e0f9
> SMB: Validate negotiate (to protect against downgrade) even if signing off
> 
> is backported in stable trees as of: 4.9.53, 4.4.90, 3.18.73

Thanks, I originally tried to backport this, but it applied in an odd
way.  I've fixed it up by hand now.

greg k-h