netdev - Re: [PATCH net-next 0/3] ipmr/ip6mr: add Netlink notifications on cache reports

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Date:   Wed, 14 Jun 2017 14:51:35 -0700
From:   Julien Gomes <julien@...sta.com>
To:     Nikolay Aleksandrov <nikolay@...ulusnetworks.com>,
        davem@...emloft.net
Cc:     Netdev <netdev@...r.kernel.org>,
        Donald Sharp <sharpd@...ulusnetworks.com>
Subject: Re: [PATCH net-next 0/3] ipmr/ip6mr: add Netlink notifications on
 cache reports

Hi Nikolay,

On 06/14/2017 05:04 AM, Nikolay Aleksandrov wrote:

> This has been on our todo list and I'm definitely interested in the implementation.
> A few things that need careful consideration from my POV. First are the security
> implications - this sends rtnl multicast messages but the rtnl socket has
> the NL_CFG_F_NONROOT_RECV flag thus allowing any user on the system to listen in.
> This would allow them to see the full packets and all reports (granted they can see
> the notifications even now), but the full packet is like giving them the opportunity
> to tcpdump the PIM traffic.

I definitely see how this can be an issue.
>From what I see, this means that either the packet should be
transmitted another way, or another Netlink family should be used.

NETLINK_ROUTE looks to be the logical family to choose though,
but then I do not see a proper other way to handle this.

However I may just not be looking into the right direction,
maybe you currently have another approach in mind?

> My second (more fixable and minor) concern is about the packet itself, how do you
> know that the packet is all linear so you can directly copy it ?

Indeed, I overlooked this possibility in this version.
I will improve that.

-- 
Julien Gomes