On Tue, Jun 01, 2021 at 01:26:02PM -0700, Jakub Kicinski wrote:
> On Tue, 1 Jun 2021 10:06:54 +0200 Christian Brauner wrote:
> > > I'm not sure why we'd pick runtime checks for something that can be
> > > perfectly easily solved at compilation time. Networking should not
> > > be asking for FDs for objects which don't exist.
> >
> > Agreed!
> > This should be fixable by sm like:
> >
> > diff --git a/net/socket.c b/net/socket.c
> > index 27e3e7d53f8e..2484466d96ad 100644
> > --- a/net/socket.c
> > +++ b/net/socket.c
> > @@ -1150,10 +1150,12 @@ static long sock_ioctl(struct file *file, unsigned cmd, unsigned long arg)
> > break;
> > case SIOCGSKNS:
> > err = -EPERM;
> > +#ifdef CONFIG_NET_NS
> > if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
> > break;
> >
> > err = open_related_ns(&net->ns, get_net_ns);
> > +#endif
> > break;
> > case SIOCGSTAMP_OLD:
> > case SIOCGSTAMPNS_OLD:
>
> Thanks! You weren't CCed on v1, so FWIW I was suggesting
> checking in get_net_ns(), to catch other callers:
>
> diff --git a/net/socket.c b/net/socket.c
> index 27e3e7d53f8e..3b44f2700e0c 100644
> --- a/net/socket.c
> +++ b/net/socket.c
> @@ -1081,6 +1081,8 @@ static long sock_do_ioctl(struct net *net, struct socket *sock,
>
> struct ns_common *get_net_ns(struct ns_common *ns)
> {
> + if (!IS_ENABLED(CONFIG_NET_NS))
> + return ERR_PTR(-EOPNOTSUPP);
> return &get_net(container_of(ns, struct net, ns))->ns;
> }
> EXPORT_SYMBOL_GPL(get_net_ns);
Yeah, that's better than my hack. :) Maybe this function should simply
move over to net/core/net_namespace.c with the other netns getters, e.g.
get_net_ns_by_fd()?
#ifdef CONFIG_NET_NS
[...]
struct net *get_net_ns_by_fd(int fd)
{
struct file *file;
struct ns_common *ns;
struct net *net;
file = proc_ns_fget(fd);
if (IS_ERR(file))
return ERR_CAST(file);
ns = get_proc_ns(file_inode(file));
if (ns->ops == &netns_operations)
net = get_net(container_of(ns, struct net, ns));
else
net = ERR_PTR(-EINVAL);
fput(file);
return net;
}
#else
struct net *get_net_ns_by_fd(int fd)
{
return ERR_PTR(-EINVAL);
}
#endif
EXPORT_SYMBOL_GPL(get_net_ns_by_fd);
Christian
