netdev - Re: [patch 2/4] mISDN: add support for group membership check

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Message-ID: <523C5141.4080608@suse.cz>
Date:	Fri, 20 Sep 2013 15:44:33 +0200
From:	Jiri Slaby <jslaby@...e.cz>
To:	Ben Hutchings <ben@...adent.org.uk>, akpm@...ux-foundation.org,
	jeffm@...e.com
CC:	davem@...emloft.net, netdev@...r.kernel.org, isdn4linux@...pen.de,
	isdn@...ux-pingi.de, sergei.shtylyov@...entembedded.com
Subject: Re: [patch 2/4] mISDN: add support for group membership check

On 09/15/2013 01:28 AM, Ben Hutchings wrote:
>> @@ -694,6 +699,10 @@ base_sock_ioctl(struct socket *sock, uns 
>> case IMSETDEVNAME: { struct mISDN_devrename dn; +		if
>> (!capable(CAP_SYS_ADMIN) && +				!gid_eq(misdn_permitted_gid,
>> current_gid()) && +				!in_group_p(misdn_permitted_gid)) +
>> return -EPERM; if (copy_from_user(&dn, (void __user *)arg, 
>> sizeof(dn))) { err = -EFAULT;
> 
> This seems to be the important bit: renaming of devices (if allowed
> at all) ought to be limited to CAP_SYS_ADMIN or possibly
> CAP_NET_ADMIN. But why should the group that is allowed to use
> mISDN data sockets also be allowed to do this?

This is based on an old patch we are dragging in SUSE since 2009:
http://www.isdn4linux.de/pipermail/isdn4linux/2009-December/004493.html
https://bugzilla.novell.com/show_bug.cgi?id=564423

The whole point of the gid-based access was to still allow some user
group to manipulate the device in an arbitrary way.

So if everybody agrees I will just disallow rename to
non-CAP_NET_ADMIN users and we are done?

thanks,
-- 
js
suse labs
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