netdev - Re: [Devel] Re: [RFC][PATCH] IP address restricting cgroup subsystem

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <6599ad830901131807n3acf6936g2028fc5f7edd6264@mail.gmail.com>
Date:	Tue, 13 Jan 2009 18:07:51 -0800
From:	Paul Menage <menage@...gle.com>
To:	Li Zefan <lizf@...fujitsu.com>
Cc:	Grzegorz Nosek <root@...aldomain.pl>, containers@...ts.osdl.org,
	netdev@...r.kernel.org
Subject: Re: [Devel] Re: [RFC][PATCH] IP address restricting cgroup subsystem

>
> I think the only way to make hierarchy_mutex works for this issue is:
>
> @@ -2403,16 +2403,18 @@ static long cgroup_create(struct cgroup *parent, struct
>        if (notify_on_release(parent))
>                set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
>
> +       cgroup_lock_hierarchy(root);
> +
>        for_each_subsys(root, ss) {
>                struct cgroup_subsys_state *css = ss->create(ss, cgrp);
>                if (IS_ERR(css)) {
> +                       cgroup_unlock_hierarchy(root);
>                        err = PTR_ERR(css);
>                        goto err_destroy;
>                }
>                init_cgroup_css(css, ss, cgrp);
>        }
>
> -       cgroup_lock_hierarchy(root);
>        list_add(&cgrp->sibling, &cgrp->parent->children);
>        cgroup_unlock_hierarchy(root);
>        root->number_of_cgroups++;
>

That would be possible, but I'm not sure that extending
hierarchy_mutex across all the create calls is a good idea - it's
meant to be very lightweight.

OK, an alternative way to avoid cgroup_lock() is for the
spinlock-protected state in ipcgroup to be the address and the count
of active children.

create() does:

lock parent
css->addr = parent->addr
parent->child_count++;
unlock parent

and write does:

lock css
if (!css->child_count) {
  css->addr = new_addr
} else {
  report error;
}
unlock css

Paul
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html