From: Mimi Zohar <zohar@linux.ibm.com>
To: Sumit Garg <sumit.garg@linaro.org>
Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
James Bottomley <jejb@linux.ibm.com>,
David Howells <dhowells@redhat.com>,
Jens Wiklander <jens.wiklander@linaro.org>,
Jonathan Corbet <corbet@lwn.net>,
James Morris <jmorris@namei.org>,
"Serge E. Hallyn" <serge@hallyn.com>,
Casey Schaufler <casey@schaufler-ca.com>,
Janne Karhunen <janne.karhunen@gmail.com>,
Daniel Thompson <daniel.thompson@linaro.org>,
Markus Wamser <Markus.Wamser@mixed-mode.de>,
Luke Hinds <lhinds@redhat.com>,
"open list:ASYMMETRIC KEYS" <keyrings@vger.kernel.org>,
linux-integrity@vger.kernel.org,
linux-security-module@vger.kernel.org,
Linux Doc Mailing List <linux-doc@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
op-tee@lists.trustedfirmware.org
Subject: Re: [PATCH v7 1/4] KEYS: trusted: Add generic trusted keys framework
Date: Wed, 21 Oct 2020 08:25:31 -0400 [thread overview]
Message-ID: <7b2ccd620a9de5c2fd57b8e8aeb41d5476f83b28.camel@linux.ibm.com> (raw)
In-Reply-To: <CAFA6WYM7aJwP9j_ayGvbJPu-cyv87rsm9N4Wj2OCOMnmfDx+Rw@mail.gmail.com>
On Wed, 2020-10-21 at 11:16 +0530, Sumit Garg wrote:
> Thanks Mimi for your comments.
>
> On Wed, 21 Oct 2020 at 08:51, Mimi Zohar <zohar@linux.ibm.com> wrote:
> >
> > On Wed, 2020-10-07 at 15:37 +0530, Sumit Garg wrote:
> >
> > > +/*
> > > + * trusted_destroy - clear and free the key's payload
> > > + */
> > > +static void trusted_destroy(struct key *key)
> > > +{
> > > + kfree_sensitive(key->payload.data[0]);
> > > +}
> > > +
> > > +struct key_type key_type_trusted = {
> > > + .name = "trusted",
> > > + .instantiate = trusted_instantiate,
> > > + .update = trusted_update,
> > > + .destroy = trusted_destroy,
> > > + .describe = user_describe,
> > > + .read = trusted_read,
> > > +};
> > > +EXPORT_SYMBOL_GPL(key_type_trusted);
> > > +
> > > +static int __init init_trusted(void)
> > > +{
> > > + int i, ret = 0;
> > > +
> > > + for (i = 0; i < ARRAY_SIZE(trusted_key_sources); i++) {
> > > + if (trusted_key_source &&
> > > + strncmp(trusted_key_source, trusted_key_sources[i].name,
> > > + strlen(trusted_key_sources[i].name)))
> > > + continue;
> > > +
> > > + trusted_key_ops = trusted_key_sources[i].ops;
> > > +
> > > + ret = trusted_key_ops->init();
> > > + if (!ret)
> > > + break;
> > > + }
> >
> > In the case when the module paramater isn't specified and both TPM and
> > TEE are enabled, trusted_key_ops is set to the last source initialized.
>
> I guess there is some misunderstanding. Here it's only a single trust
> source (TPM *or* TEE) is initialized and only that trust source would
> be active at runtime. And trusted_key_ops would be initialized to the
> first trust source whose initialization is successful (see check: "if
> (!ret)").
My mistake.
>
> > After patch 2/4, the last trusted source initialized is TEE. If the
> > intention is to limit it to either TPM or TEE, then trusted_key_ops
> > should have a default value, which could be overwritten at runtime.
> > That would address Luke Hind's concerns of making the decision at
> > compile time.
>
> I think traversing the trust source list with the initial value being
> TPM would be default value.
Agreed
>
> >
> > trusted_key_ops should be defined as __ro_after_init, like is currently
> > done for other LSM structures.
>
> Sure, will do.
Thanks
>
> >
> > > +
> > > + /*
> > > + * encrypted_keys.ko depends on successful load of this module even if
> > > + * trusted key implementation is not found.
> > > + */
> > > + if (ret == -ENODEV)
> > > + return 0;
> > > +
> > > + return ret;
> > > +}
> > > +
> > > +static void __exit cleanup_trusted(void)
> > > +{
> > > + trusted_key_ops->exit();
> >
> > If the intention is really to support both TPM and TEE trusted keys at
> > the same time, as James suggested, then the same "for" loop as in
> > init_trusted() is needed here and probably elsewhere.
>
> Current intention is to only support a single trust source (TPM or
> TEE) at runtime. But in future if there are use-cases then framework
> can be extended to support multiple trust sources at runtime as well.
Ok, the last sentence of the patch description, "Also, add a module
parameter in order to select a particular trust source in case a
platform support multiple trust sources.", needs to be expanded to:
- indicate only one trust source at a time is supported
- indicate the default, if the module_param is not specified
I would also change the word from "add" to "define". The new "source"
module parameter needs to be added to the admin-guide/kernel-parameters
documentation.
thanks,
Mimi
next prev parent reply other threads:[~2020-10-21 12:26 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-07 10:19 [PATCH v7 0/4] Introduce TEE based Trusted Keys support Sumit Garg
2020-10-07 10:19 ` [PATCH v7 1/4] KEYS: trusted: Add generic trusted keys framework Sumit Garg
2020-10-13 1:43 ` Jarkko Sakkinen
2020-10-13 10:53 ` Sumit Garg
2020-10-13 11:59 ` Jarkko Sakkinen
2020-10-14 5:16 ` Sumit Garg
2020-10-21 3:21 ` Mimi Zohar
2020-10-21 5:46 ` Sumit Garg
2020-10-21 12:25 ` Mimi Zohar [this message]
2020-10-22 11:40 ` Sumit Garg
2020-10-07 10:19 ` [PATCH v7 2/4] KEYS: trusted: Introduce TEE based Trusted Keys Sumit Garg
2020-10-13 1:52 ` Jarkko Sakkinen
2020-10-13 11:13 ` Sumit Garg
2020-10-07 10:19 ` [PATCH v7 3/4] doc: trusted-encrypted: updates with TEE as a new trust source Sumit Garg
2020-10-07 10:19 ` [PATCH v7 4/4] MAINTAINERS: Add entry for TEE based Trusted Keys Sumit Garg
2020-10-13 2:21 ` Jarkko Sakkinen
2020-10-13 11:40 ` Sumit Garg
2020-10-13 13:40 ` Jarkko Sakkinen
2020-10-14 5:18 ` Sumit Garg
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