Re: [PATCH 2/2] KEYS: Add per-user_namespace registers for persistent per-UID kerberos caches

From: David Howells
Date: Fri Aug 02 2013 - 13:05:39 EST

Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote:

> > The cache returned is a keyring named "_krb.<uid>" that the possessor can
> > read, search, clear, invalidate, unlink from and add links to. SELinux
> > and co. get a say as to whether this call will succeed as the caller must
> > have LINK permission on the cache keyring.
> I think it would be more accurate to say you use the existing LSM
> security hooks for security keys.


> Calling out SELinux in particular just seems odd as there is absolutely
> nothing SELinux specific in this patch.

Sorry, I normally think of SELinux as that's what I usually deal with. Yes,
any and all LSMs.

> > + !nsown_capable(CAP_SETUID))
> You you make this ns_capable(ns, CAP_SETUID);
> nsown_capable is the right thing here but I am trying to remove the
> function because it makes it too easy to not think about which
> user namespace you are in.


> > + index_key.desc_len = sprintf(buf, "_krb.%u", __kuid_val(uid));
> Please don't use the implementation detail __kuid_val. Please use
> from_kuid(&init_user_ns, uid) instead so it is explicitly documented
> which user namespace you are using.

Actually, I don't want that either. I want the user-visible UID from the

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