On Tue, Jul 07, 2020 at 02:22:20PM +0200, Christian Brauner wrote:
> So while the patch is correct it leaves 5.6 and 5.7 with a bug in the
> pidfd_getfd() implementation and that just doesn't seem right. I'm
> wondering whether we should introduce:
>
> void sock_update(struct file *file)
> {
> struct socket *sock;
> int error;
>
> sock = sock_from_file(file, &error);
> if (sock) {
> sock_update_netprioidx(&sock->sk->sk_cgrp_data);
> sock_update_classid(&sock->sk->sk_cgrp_data);
> }
> }
>
> and switch pidfd_getfd() over to:
>
> diff --git a/kernel/pid.c b/kernel/pid.c
> index f1496b757162..c26bba822be3 100644
> --- a/kernel/pid.c
> +++ b/kernel/pid.c
> @@ -642,10 +642,12 @@ static int pidfd_getfd(struct pid *pid, int fd)
> }
>
> ret = get_unused_fd_flags(O_CLOEXEC);
> - if (ret < 0)
> + if (ret < 0) {
> fput(file);
> - else
> + } else {
> + sock_update(file);
> fd_install(ret, file);
> + }
>
> return ret;
> }
>
> first thing in the series and then all of the other patches on top of it
> so that we can Cc stable for this and that can get it backported to 5.6,
> 5.7, and 5.8.
>
> Alternatively, I can make this a separate bugfix patch series which I'll
> send upstream soonish. Or we have specific patches just for 5.6, 5.7,
> and 5.8. Thoughts?
Okay, I looked at hch's clean-ups again and I'm reminded why they
don't make great -stable material. :) The compat bug (also missing the
sock_update()) needs a similar fix (going back to 3.6...), so, yeah,
for ease of backport, probably an explicit sock_update() implementation
(with compat and native scm using it), and a second patch for pidfd.
Let me see what I looks best...
--
Kees Cook
