On Sun, Apr 23, 2017 at 9:24 AM, Matt Brown <matt@xxxxxxxxx> wrote: > This patch adds struct user_namespace *owner_user_ns to the tty_struct. > Then it is set to current_user_ns() in the alloc_tty_struct function. > > This is done to facilitate capability checks against the original user > namespace that allocated the tty. > > E.g. ns_capable(tty->owner_user_ns,CAP_SYS_ADMIN) > > This combined with the use of user namespace's will allow hardening > protections to be built to mitigate container escapes that utilize TTY > ioctls such as TIOCSTI. > > See: https://bugzilla.redhat.com/show_bug.cgi?id=1411256 > > Signed-off-by: Matt Brown <matt@xxxxxxxxx> > --- > drivers/tty/tty_io.c | 1 + > include/linux/tty.h | 2 ++ > 2 files changed, 3 insertions(+) > > diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c > index e6d1a65..e774385 100644 > --- a/drivers/tty/tty_io.c > +++ b/drivers/tty/tty_io.c > @@ -3191,6 +3191,7 @@ struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx) > tty->index = idx; > tty_line_name(driver, idx, tty->name); > tty->dev = tty_get_device(tty); > + tty->owner_user_ns = current_user_ns(); Why are you not taking a reference to the userns? -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html