Re: [PATCH 07/44] kdbus: Fix comment on translation of caps between namespaces

From: Hillf Danton
Date: Thu Oct 08 2015 - 23:44:20 EST


> @@ -730,15 +730,21 @@ static void kdbus_meta_export_caps(struct kdbus_meta_caps *out,
>
> /*
> * This translates the effective capabilities of 'cred' into the given
> - * user-namespace. If the given user-namespace is a child-namespace of
> - * the user-namespace of 'cred', the mask can be copied verbatim. If
> - * not, the mask is cleared.
> - * There's one exception: If 'cred' is the owner of any user-namespace
> - * in the path between the given user-namespace and the user-namespace
> - * of 'cred', then it has all effective capabilities set. This means,
> - * the user who created a user-namespace always has all effective
> - * capabilities in any child namespaces. Note that this is based on the
> - * uid of the namespace creator, not the task hierarchy.
> + * user namespace according to the following rules:
> + *
> + * - If 'cred' is a member of the given user namespace or any of its
> + * parent user namespaces, the mask is copied verbatim. That is, if

Clearer/Better if "if not, the mask is cleared." is reserved.

> + * a process has a capability in a user namespace, then it has it in
> + * all child user namespaces too.
> + *
> + * - If the effective UID of 'cred' matches the owner of the given user
> + * namespace or any of its parent user namespaces and 'cred' itself
> + * resides in the parent of that user namespace which it owns, then
> + * it has all effective capabilities set. This means that the user
> + * who created a user namespace always has all effective capabilities
> + * in all child namespaces while staying in the parent of the user
> + * namespace which it owns. Note that this is based on the UID of the
> + * namespace creator, not the task hierarchy.
> */
> for (iter = user_ns; iter; iter = iter->parent) {
> if (iter == cred->user_ns) {
> --
> 1.8.3.1
>

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