Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757485Ab1DMP2u (ORCPT ); Wed, 13 Apr 2011 11:28:50 -0400 Received: from mx1.redhat.com ([209.132.183.28]:16775 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757340Ab1DMP2t (ORCPT ); Wed, 13 Apr 2011 11:28:49 -0400 Date: Wed, 13 Apr 2011 17:28:29 +0200 From: Petr Pisar To: Chris Ball Cc: Greg Kroah-Hartman , Alan Cox , linux-kernel@vger.kernel.org, Artem Bityutskiy Subject: Re: [PATCH] Clean console safely Message-ID: <20110413152829.GB2993@dhcp-0-146.brq.redhat.com> Mail-Followup-To: Chris Ball , Greg Kroah-Hartman , Alan Cox , linux-kernel@vger.kernel.org, Artem Bityutskiy References: <1302705651.2768.21.camel@localhost> <1302706473-16519-1-git-send-email-ppisar@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1805 Lines: 46 On Wed, Apr 13, 2011 at 11:18:04AM -0400, Chris Ball wrote: > > On Wed, Apr 13 2011, Petr Písař wrote: > > Traditional \E[2J sequence erases console display but scroll-back > > buffer and underlying device (frame) buffer keep data that can be > > accessed by scrolling console back. > > > > This patch introduce new \E[J parameter 3 that allows to scramble > > scroll-back buffer explicitly. Session locking programs (screen, > > vlock) can use it to prevent attacker to browse locked console > > history. > > > > Signed-off-by: Petr Písař > > --- > > drivers/tty/vt/vt.c | 6 ++++++ > > 1 files changed, 6 insertions(+), 0 deletions(-) > > > > diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c > > index 4bea1ef..fe96a1f 100644 > > --- a/drivers/tty/vt/vt.c > > +++ b/drivers/tty/vt/vt.c > > @@ -1197,6 +1197,12 @@ static void csi_J(struct vc_data *vc, int vpar) > > vc->vc_x + 1); > > } > > break; > > + case 3: /* erase scroll-back buffer (and whole display) */ > > + scr_memsetw(vc->vc_screenbuf, vc->vc_video_erase_char, > > + vc->vc_screenbuf_size >> 1); > > + set_origin(vc); > > + if (CON_IS_VISIBLE(vc)) > > + update_screen(vc); > > case 2: /* erase whole display */ > > count = vc->vc_cols * vc->vc_rows; > > start = (unsigned short *)vc->vc_origin; > > Nitpick: the cases were ordered before -- 3 should go after 2. > This is on purpose to continue with code for case 2 as it prepares variables for cleaning visible part of display after the switch block. -- Petr -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/