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Is ovs-vsctl gonna be happy with CAP_NET_ADMIN? <br>
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<div class="moz-cite-prefix">On 12/10/2014 02:43 AM, Angus Lees
wrote:<br>
</div>
<blockquote
cite="mid:CAPA_H3c-U6f2eQrTSfqRKk+NA5ORKyP3bRFsdvDf3dh2ovDzrw@mail.gmail.com"
type="cite">[I tried to find any previous discussion of this and
failed - I'd appreciate a pointer to any email threads / specs
where this has already been discussed.]
<div><br>
</div>
<div>Currently neutron is given the ability to do just about
anything to networking via rootwrap, sudo, and the IpFilter
check (allow anything except 'netns exec'). This is completely
in line with the role a typical neutron agent is expected to
play on the local system.</div>
<div><br>
</div>
<div>There are also recurring discussions/issues around the
overhead of rootwrap, costs of sudo calls, etc - and projects
such as rootwrap daemon underway to improve this.</div>
<div><br>
</div>
<div>How crazy would it be to just give neutron CAP_NET_ADMIN
(where required), and allow it to make network changes via ip
(netlink) calls directly?</div>
<div>We will still need rootwrap/sudo for other cases, but this
should remove a lot of the separate process overhead for common
operations, make us independent of iproute cli versions, and
allow us to use a direct programmatic API (rtnetlink and other
syscalls) rather than generating command lines and regex parsing
output everywhere.</div>
<div><br>
</div>
<div>For what it's worth, CAP_NET_ADMIN is not sufficient to allow
'netns exec' (requires CAP_SYS_ADMIN), so it preserves the
IpFilter semantics. On the downside, many of the frequent
rootwrap calls _do_ involve creating/modifying network
namespaces so we wouldn't see advantages for these cases. I
need to experiment further before having a proposal for that
part (just granting CAP_SYS_ADMIN too is too broad; user
namespaces help a lot, but they're very new and scary so not
available everywhere).</div>
<div><br>
</div>
<div>Thoughts?</div>
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