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Message-Id: <1302705170-15712-2-git-send-email-ppisar@redhat.com>
Date: Wed, 13 Apr 2011 16:32:50 +0200
From: Petr Písař <ppisar@...hat.com>
To: Greg Kroah-Hartman <gregkh@...e.de>
Cc: Alan Cox <alan@...rguk.ukuu.org.uk>, linux-kernel@...r.kernel.org,
Petr Písař <ppisar@...hat.com>
Subject: [PATCH] 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.
---
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;
--
1.7.4.4
--
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