Commit f8df13e0 authored Apr 15, 2011 by Petr Písař Committed by Greg Kroah-Hartman Apr 19, 2011

tty: Clean console safely



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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

parent d9420602

drivers/tty/vt/vt.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -1193,6 +1193,13 @@ 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);
		/* fall through */
		case 2: /* erase whole display */
		count = vc->vc_cols * vc->vc_rows;
		start = (unsigned short *)vc->vc_origin;

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