linux-kernel - Re: [PATCH v3 6/7] netlink: Add multicast group level permissions

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Message-ID: <20230331111325.5703499b@kernel.org>
Date:   Fri, 31 Mar 2023 11:13:25 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Anjali Kulkarni <anjali.k.kulkarni@...cle.com>
Cc:     "davem@...emloft.net" <davem@...emloft.net>,
        "edumazet@...gle.com" <edumazet@...gle.com>,
        "pabeni@...hat.com" <pabeni@...hat.com>,
        "zbr@...emap.net" <zbr@...emap.net>,
        "brauner@...nel.org" <brauner@...nel.org>,
        "johannes@...solutions.net" <johannes@...solutions.net>,
        "ecree.xilinx@...il.com" <ecree.xilinx@...il.com>,
        "leon@...nel.org" <leon@...nel.org>,
        "keescook@...omium.org" <keescook@...omium.org>,
        "socketcan@...tkopp.net" <socketcan@...tkopp.net>,
        "petrm@...dia.com" <petrm@...dia.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH v3 6/7] netlink: Add multicast group level permissions

On Fri, 31 Mar 2023 17:48:18 +0000 Anjali Kulkarni wrote:
> > On Mar 31, 2023, at 10:24 AM, Jakub Kicinski <kuba@...nel.org> wrote:
> > On Fri, 31 Mar 2023 17:00:27 +0000 Anjali Kulkarni wrote:  
> >> Are you suggesting adding something like a new struct proto_ops for
> >> the connector family? I have not looked into that, though that would
> >> seem like a lot of work, and also I have not seen any infra structure
> >> to call into protocol specific bind from netlink bind?  
> > 
> > Where you're adding a release callback in patch 2 - there's a bind
> > callback already three lines above. What am I missing?  
> Ah yes, that one is actually meant to be used for adding(bind) and
> deleting(unbind) multicast group memberships. So it is also called
> from setsockopt() - so I think just checking for root access
> permission changes the semantics of what it is meant to be used for?
> Besides we would need to change some of that ordering there (check
> for permissions & netlink_bind call) and changing it for all users of
> netlink might not be a good idea…?

AFAICT genetlink uses that callback in the way I'm suggesting already
(see genl_bind()) so if you can spot a bug or a problem - we need to
fix it :S