iio: use anon_inode_getfd() with O_CLOEXEC flag
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/cover.1377372576.git.ydroneaud@opteya.com
Signed-off-by: Yann Droneaud <ydroneaud@opteya.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
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 @@
}
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);