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authorJiri Slaby <jslaby@suse.cz>2013-02-15 15:25:05 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-02-15 10:52:36 -0800
commitb0de59b5733d18b0d1974a060860a8b5c1b36a2e (patch)
treeb304fafe3dcbb26212d95438fe2d98184752b9fc /drivers/tty/tty_io.c
parentcb8081cb6bfbdb867d17cafaaf3509ee31140f7f (diff)
TTY: do not update atime/mtime on read/write
On http://vladz.devzero.fr/013_ptmx-timing.php, we can see how to find out length of a password using timestamps of /dev/ptmx. It is documented in "Timing Analysis of Keystrokes and Timing Attacks on SSH". To avoid that problem, do not update time when reading from/writing to a TTY. I am afraid of regressions as this is a behavior we have since 0.97 and apps may expect the time to be current, e.g. for monitoring whether there was a change on the TTY. Now, there is no change. So this would better have a lot of testing before it goes upstream. References: CVE-2013-0160 Signed-off-by: Jiri Slaby <jslaby@suse.cz> Cc: stable <stable@vger.kernel.org> # after 3.9 is out Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/tty_io.c')
-rw-r--r--drivers/tty/tty_io.c8
1 files changed, 2 insertions, 6 deletions
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 54a254ab85c..8f44d627cce 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -977,8 +977,7 @@ static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
else
i = -EIO;
tty_ldisc_deref(ld);
- if (i > 0)
- inode->i_atime = current_fs_time(inode->i_sb);
+
return i;
}
@@ -1079,11 +1078,8 @@ static inline ssize_t do_tty_write(
break;
cond_resched();
}
- if (written) {
- struct inode *inode = file->f_path.dentry->d_inode;
- inode->i_mtime = current_fs_time(inode->i_sb);
+ if (written)
ret = written;
- }
out:
tty_write_unlock(tty);
return ret;