From c61642cce0247175489666d90ebd59f8a04e7c76 Mon Sep 17 00:00:00 2001 From: Jiri Slaby Date: Fri, 26 Apr 2013 13:48:53 +0200 Subject: [PATCH] TTY: fix atime/mtime regression commit 37b7f3c76595e23257f61bd80b223de8658617ee upstream. In commit b0de59b5733d ("TTY: do not update atime/mtime on read/write") we removed timestamps from tty inodes to fix a security issue and waited if something breaks. Well, 'w', the utility to find out logged users and their inactivity time broke. It shows that users are inactive since the time they logged in. To revert to the old behaviour while still preventing attackers to guess the password length, we update the timestamps in one-minute intervals by this patch. Signed-off-by: Jiri Slaby Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- drivers/tty/tty_io.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index 60236a21f0ad..bf9f98750f4f 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -938,6 +938,14 @@ void start_tty(struct tty_struct *tty) EXPORT_SYMBOL(start_tty); +static void tty_update_time(struct timespec *time) +{ + unsigned long sec = get_seconds(); + sec -= sec % 60; + if ((long)(sec - time->tv_sec) > 0) + time->tv_sec = sec; +} + /** * tty_read - read method for tty device files * @file: pointer to tty file @@ -975,6 +983,9 @@ static ssize_t tty_read(struct file *file, char __user *buf, size_t count, i = -EIO; tty_ldisc_deref(ld); + if (i > 0) + tty_update_time(&inode->i_atime); + return i; } @@ -1075,8 +1086,11 @@ static inline ssize_t do_tty_write( break; cond_resched(); } - if (written) + if (written) { + struct inode *inode = file->f_path.dentry->d_inode; + tty_update_time(&inode->i_mtime); ret = written; + } out: tty_write_unlock(tty); return ret; -- 2.39.5