Re: [RFC v2 09/10] landlock: Handle cgroups (netfilter match)

["Mickaël Salaün" <mic@digikod.net>]

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On 27/08/2016 01:05, Alexei Starovoitov wrote:
> On Fri, Aug 26, 2016 at 05:10:40PM +0200, Mickaël Salaün wrote:
>> To sum up, there is four related patchsets:
>> * "Landlock LSM: Unprivileged sandboxing" (this series)
>> * "Add Checmate, BPF-driven minor LSM" (Sargun Dhillon)
>> * "Networking cgroup controller" (Anoop Naravaram)
>> * "Add eBPF hooks for cgroups" (Daniel Mack)

>>> Anoop Naravaram's use case is to control the ports the applications
>>> under cgroup can bind and listen on.
>>> Such use case can be solved by such 'lsm cgroup controller' by
>>> attaching bpf program to security_socket_bind lsm hook and
>>> filtering sockaddr.
>>> Furthermore Sargun's use case is to allow further sockaddr rewrites
>>> from the bpf program which can be done as natural extension
>>> of such mechanism.
>>>
>>> If I understood Daniel's Anoop's Sargun's and yours use cases
>>> correctly the common piece of kernel infrastructure that can solve
>>> them all can start from Daniel's current set of patches that
>>> establish a mechanism of attaching bpf program to a cgroup.
>>> Then adding lsm hooks to it and later allowing argument rewrite
>>> (since they're already in the kernel and no ToCToU problems exist)

>> For the network-related series, I think it make more sense to simply
>> create a netfilter rule matching a cgroup and then add more features to
>> netfilter (restrict port ranges and so on) thanks to eBPF programs.
>> Containers are (usually) in a dedicated network namespace, which open
>> the possibility to not only rely on cgroups (e.g. match UID,
>> netmask...). It would also be more flexible to be able to load a BPF
>> program in netfilter and update its maps on the fly to make dynamic
>> rules, like ipset does, but in a more generic way.

What do the netdev folks think about this design?


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