On 09/06/13 11:39, Yann Droneaud wrote:
> IIO uses anon_inode_get() to allocate file descriptors as part
> of its ioctls. But those ioctls are lacking a flag argument
> allowing userspace to choose options for the newly opened file
> descriptor.
>
> In such case it's advised to use O_CLOEXEC by default so that
> userspace is allowed to choose, without race, if the file descriptor
> is going to be inherited across exec().
>
> KVM usage of anon_inode_getfd() was fixed in a previous patchset [1],
> so IIO is the only subsystem using anon_inode_getfd() with a fixed set
> of flags not including O_CLOEXEC.
>
> This patch set O_CLOEXEC flag on the event file descriptor created
> with anon_inode_getfd() to not leak file descriptors across exec().
>
> Links:
>
> - Secure File Descriptor Handling (Ulrich Drepper, 2008)
> http://udrepper.livejournal.com/20407.html
>
> - Excuse me son, but your code is leaking !!! (Dan Walsh, March 2012)
> http://danwalsh.livejournal.com/53603.html
>
> - [1] kvm: use anon_inode_getfd() with O_CLOEXEC flag
> http://lkml.kernel.org/r/[email protected]
>
> Signed-off-by: Yann Droneaud <[email protected]>
> Link: http://lkml.kernel.org/r/[email protected]
Thanks Yann. I had no idea about this issue but your well supported description
above made this easy to review.
Applied to the togreg branch of
git://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git
as it's not a regression but if there is support for pushing this back to stable
I personally am not against it.
Jonathan
>
---
> drivers/iio/industrialio-event.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/iio/industrialio-event.c
> b/drivers/iio/industrialio-event.c
> index 10aa9ef..2390e3d 100644
> --- a/drivers/iio/industrialio-event.c
> +++ b/drivers/iio/industrialio-event.c
> @@ -159,7 +159,7 @@ int iio_event_getfd(struct iio_dev *indio_dev)
> }
> spin_unlock_irq(&ev_int->wait.lock);
> fd = anon_inode_getfd("iio:event",
> - &iio_event_chrdev_fileops, ev_int, O_RDONLY);
> + &iio_event_chrdev_fileops, ev_int, O_RDONLY |
> O_CLOEXEC);
> if (fd < 0) {
> spin_lock_irq(&ev_int->wait.lock);
> __clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
>
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