[lxc-devel] capset fails with userns

[Stephan Sachse]

> Look at security/commoncap.c:cap_inode_setxattr()
>
> Whereas file ownership is properly namespaced, and task capabilities
> are properly namespaced, file capabilities are more problematic.  To
> support this, I think we'd need a new capability xattr format.  If we
> add the kuid_t of the user_namespace root id, I think we could safely
> support this.

sorry for this :) but i'm not a kernel/c programmer.

maybe there must be more then one cap set per file.

security.capability for the init_ns
security.capability.{kuid_t} for the userns

the name of the xattr must be transparently mapped.

in userns for get*() if there is no security.capability.{kuid_t} use
the security.capability. but never write to security.capability always
to security.capability.{kuid_t}

or the format of security.capability must be changed to support more
then one set of caps. every capability set must be associated with a
kuid_t.

back to line one of my mail: i'm not a kernel/c programmer :'(

/stephan

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