userns: Add a more complete capability subset test to commit_creds

	return ret;

}

static bool cred_cap_issubset(const struct cred *set, const struct cred *subset)

{

	const struct user_namespace *set_ns = set->user_ns;

	const struct user_namespace *subset_ns = subset->user_ns;

	/* If the two credentials are in the same user namespace see if

	 * the capabilities of subset are a subset of set.

	 */

	if (set_ns == subset_ns)

		return cap_issubset(subset->cap_permitted, set->cap_permitted);

	/* The credentials are in a different user namespaces

	 * therefore one is a subset of the other only if a set is an

	 * ancestor of subset and set->euid is owner of subset or one

	 * of subsets ancestors.

	 */

	for (;subset_ns != &init_user_ns; subset_ns = subset_ns->parent) {

		if ((set_ns == subset_ns->parent)  &&

		    uid_eq(subset_ns->owner, set->euid))

			return true;

	}

	return false;

}

/**

 * commit_creds - Install new credentials upon the current task

 * @new: The credentials to be assigned

	    !gid_eq(old->egid, new->egid) ||

	    !uid_eq(old->fsuid, new->fsuid) ||

	    !gid_eq(old->fsgid, new->fsgid) ||

	    !cap_issubset(new->cap_permitted, old->cap_permitted)) {

	    !cred_cap_issubset(old, new)) {

		if (task->mm)

			set_dumpable(task->mm, suid_dumpable);

		task->pdeath_signal = 0;