In situations where docker runs in an environment where capabilities are limited,
sucn as docker-in-docker in a container created by older versions of docker, or
in a container where some capabilities have been disabled, starting a privileged
container may fail, because even though the _kernel_ supports a capability, the
capability is not available.
This patch attempts to address this problem by limiting the list of "known" capa-
bilities on the set of effective capabilties for the current process. This code
is based on the code in containerd's "caps" package.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
