Messages in this thread |  | | From | Chris Ball <> | Subject | Re: [PATCH] Clean console safely | Date | Wed, 13 Apr 2011 11:44:48 -0400 |
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Hi,
On Wed, Apr 13 2011, Petr Pisar wrote: > 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 <ppisar@redhat.com> >> > --- >> > 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.
Oops, sorry; I saw an imaginary break statement there.
- Chris. -- Chris Ball <cjb@laptop.org> <http://printf.net/> One Laptop Per Child -- 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/
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