On Wed, Jun 24, 2020 at 01:44:37PM +0200, Michal Koutný wrote:
> Hi.
>
> On Tue, May 05, 2020 at 04:04:31PM +0200, Christian Brauner <christian.brauner@xxxxxxxxxx> wrote:
> > -SYSCALL_DEFINE2(setns, int, fd, int, nstype)
> > +SYSCALL_DEFINE2(setns, int, fd, int, flags)
> > [...]
> > - file = proc_ns_fget(fd);
> > - if (IS_ERR(file))
> > - return PTR_ERR(file);
> > + int err = 0;
> >
> > - err = -EINVAL;
> > - ns = get_proc_ns(file_inode(file));
> > - if (nstype && (ns->ops->type != nstype))
> > + file = fget(fd);
> > + if (!file)
> > + return -EBADF;
> > +
> > + if (proc_ns_file(file)) {
> > + ns = get_proc_ns(file_inode(file));
> > + if (flags && (ns->ops->type != flags))
> > + err = -EINVAL;
> > + flags = ns->ops->type;
> > + } else if (pidfd_pid(file)) {
> > + err = check_setns_flags(flags);
> > + } else {
> > + err = -EBADF;
> > + }
> > + if (err)
> > goto out;
> >
> > - err = prepare_nsset(ns->ops->type, &nsset);
> > + err = prepare_nsset(flags, &nsset);
> > if (err)
> > goto out;
> This modification changed the returned error when a valid file
> descriptor is passed but it doesn't represent a namespace (nor pidfd).
> The error is now EBADF although originally and per man page it
> was/should be EINVAL.
>
> A change like below would restore it, however, I see it may be less
> consistent with other pidfd calls(?), then I'd suggest updating the
> manpage to capture this.
>
> --- a/kernel/nsproxy.c
> +++ b/kernel/nsproxy.c
> @@ -531,7 +531,7 @@ SYSCALL_DEFINE2(setns, int, fd, int, flags)
> } else if (!IS_ERR(pidfd_pid(file))) {
> err = check_setns_flags(flags);
> } else {
> - err = -EBADF;
> + err = -EINVAL;
> }
> if (err)
> goto out;
>
> I noticed this breaks systemd self tests [1].
Yep, I already have a fix for this in my tree based on a previous report
from LTP. It's sitting in linux-next:
https://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux.git/commit/?h=fixes&id=e571d4ee334719727f22cce30c4c74471d4ef68a
with selftests:
https://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux.git/commit/?h=fixes&id=86f56395feb2b106b125c47e72192e37da5dd088
I'll send it to Linus this week.
Thanks!
Christian
