From 37b7f3c76595e23257f61bd80b223de8658617ee Mon Sep 17 00:00:00 2001 From: Jiri Slaby Date: Fri, 26 Apr 2013 13:48:53 +0200 Subject: TTY: fix atime/mtime regression 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 Cc: Greg Kroah-Hartman Signed-off-by: Linus Torvalds --- drivers/tty/tty_io.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index 05400acbc45..b0452688308 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -941,6 +941,14 @@ 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 @@ -960,10 +968,11 @@ static ssize_t tty_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) { int i; + struct inode *inode = file_inode(file); struct tty_struct *tty = file_tty(file); struct tty_ldisc *ld; - if (tty_paranoia_check(tty, file_inode(file), "tty_read")) + if (tty_paranoia_check(tty, inode, "tty_read")) return -EIO; if (!tty || (test_bit(TTY_IO_ERROR, &tty->flags))) return -EIO; @@ -977,6 +986,9 @@ 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; } @@ -1077,8 +1089,10 @@ static inline ssize_t do_tty_write( break; cond_resched(); } - if (written) + if (written) { + tty_update_time(&file_inode(file)->i_mtime); ret = written; + } out: tty_write_unlock(tty); return ret; -- cgit v1.2.3