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Bug#884641: ITP: lwip -- small implementation of the TCP/IP protocol suite



On Mon, 2017-12-18 at 01:44 +0100, Samuel Thibault wrote:
> Ben Hutchings, on lun. 18 déc. 2017 00:37:48 +0000, wrote:
> > On Mon, 2017-12-18 at 00:12 +0100, Samuel Thibault wrote:
> > > It can be used as a maintained user-land TCP/IP stack.
> > 
> > Why would this be useful for Debian systems, which already have a much
> > better performing TCP/IP stack?
> 
> But the kernel-provided stack can't be manipulated by userland for
> e.g. VPNs, ppp, etc. without having to be root.
[...]

Not quite.  On Linux you need CAP_NET_ADMIN in some user namespace.  To
use lwip you would presumably need raw access to a network device,
which also requires a privileged capability.

If you enable unprivileged user namespaces in Linux then any user is
allowed to create a new user namespace, and a net namespace owned by
it, and then to create and configure various kinds of virtual device
within that net namespace.  (In Debian this feature is guarded by a
sysctl that's off by default, as a security mitigation.)

Even if that's disabled, a privileged container manager can create a
new user namespace and start a container within that namespace with the
CAP_NET_ADMIN capability.

Ben.

-- 
Ben Hutchings
73.46% of all statistics are made up.

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