3.8-stable review patch. If anyone has any objections, please let me know.
------------------ From: Jiri Slaby <jsl...@suse.cz> commit b0de59b5733d18b0d1974a060860a8b5c1b36a2e upstream. 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 <jsl...@suse.cz> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- drivers/tty/tty_io.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -977,8 +977,7 @@ static ssize_t tty_read(struct file *fil 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; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
