linux/drivers/tty/tty_io.c, branch v3.4.98

tty: fix up atime/mtime mess, take three

2013-05-08T02:51:53Z

commit b0b885657b6c8ef63a46bc9299b2a7715d19acde upstream. We first tried to avoid updating atime/mtime entirely (commit b0de59b5733d: "TTY: do not update atime/mtime on read/write"), and then limited it to only update it occasionally (commit 37b7f3c76595: "TTY: fix atime/mtime regression"), but it turns out that this was both insufficient and overkill. It was insufficient because we let people attach to the shared ptmx node to see activity without even reading atime/mtime, and it was overkill because the "only once a minute" means that you can't really tell an idle person from an active one with 'w'. So this tries to fix the problem properly. It marks the shared ptmx node as un-notifiable, and it lowers the "only once a minute" to a few seconds instead - still long enough that you can't time individual keystrokes, but short enough that you can tell whether somebody is active or not. Reported-by: Simon Kirby Acked-by: Jiri Slaby Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

TTY: fix atime/mtime regression

2013-05-01T16:41:03Z

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

TTY: do not update atime/mtime on read/write

2013-05-01T16:41:03Z

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 Signed-off-by: Greg Kroah-Hartman

Remove all #inclusions of asm/system.h

2012-03-28T17:30:03Z

Remove all #inclusions of asm/system.h preparatory to splitting and killing it. Performed with the following command: perl -p -i -e 's!^#\s*include\s*.*\n!!' `grep -Irl '^#\s*include\s*' *` Signed-off-by: David Howells

TTY: remove tty driver re-set from tty_reopen

2012-03-08T19:38:50Z

This is from tty_reopen: struct tty_driver *driver = tty->driver; ... tty->driver = driver; and it doesn't make sense at all. The driver is intended to be set in initialize_tty_struct from tty_init_dev (initial open). So this set in tty_reopen is not needed. Signed-off-by: Jiri Slaby Signed-off-by: Greg Kroah-Hartman

TTY: simplify tty_driver_lookup_tty a bit

2012-03-08T19:38:50Z

Remove the useless local variable and return the value itself. Signed-off-by: Jiri Slaby Signed-off-by: Greg Kroah-Hartman

TTY: let alloc_tty_driver deduce the owner automatically

2012-03-08T19:30:21Z

Like the rest of the kernel, make a stub from alloc_tty_driver which calls __alloc_tty_driver with proper owner. This will save us one more assignment on the driver side. Also this fixes some drivers which didn't set the owner. This allowed user to remove the module from the system even though a tty from the driver is still open. Signed-off-by: Jiri Slaby Signed-off-by: Greg Kroah-Hartman

TTY: tty_io, remove buffer re-assignments

2012-03-08T19:30:21Z

TTY buffer head and tail are initialized in tty_buffer_init. No need to do it once again in initialize_tty_struct where tty_buffer_init is called. Signed-off-by: Jiri Slaby Signed-off-by: Greg Kroah-Hartman

Revert "TTY: get rid of BTM around devpts_*"

2012-02-24T21:55:54Z

This reverts commit d3bda5298aad98c7a27678bdd0dd9d008ab9e685. Sasha reported that this causes problems, so revert it. Cc: Sasha Levin Cc: Jiri Slaby Signed-off-by: Greg Kroah-Hartman

TTY: get rid of BTM around devpts_*

2012-02-02T23:10:46Z

devpts operations are protected by inode mutexes and dentry refcounting. There is no need to hold BTM. Signed-off-by: Jiri Slaby Signed-off-by: Greg Kroah-Hartman