From: Dan Williams <dan.j.williams@intel.com>
To: James Bottomley <jejb@linux.ibm.com>
Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
Roberto Sassu <roberto.sassu@huawei.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Mimi Zohar <zohar@linux.ibm.com>,
David Howells <dhowells@redhat.com>,
keyrings@vger.kernel.org
Subject: Re: [PATCH] security/keys/trusted: Allow operation without hardware TPM
Date: Mon, 18 Mar 2019 18:34:02 -0700 [thread overview]
Message-ID: <CAPcyv4h7iPHT2qSgPYvw8o61cdwfzjpocSDj0YF7LSsxEoO3fA@mail.gmail.com> (raw)
In-Reply-To: <1552956989.2785.31.camel@linux.ibm.com>
On Mon, Mar 18, 2019 at 5:56 PM James Bottomley <jejb@linux.ibm.com> wrote:
>
> On Mon, 2019-03-18 at 17:30 -0700, Dan Williams wrote:
> > On Mon, Mar 18, 2019 at 5:24 PM James Bottomley <jejb@linux.ibm.com>
> > wrote:
> > >
> > > On Mon, 2019-03-18 at 16:45 -0700, Dan Williams wrote:
> > > > Rather than fail initialization of the trusted.ko module, arrange
> > > > for the module to load, but rely on trusted_instantiate() to fail
> > > > trusted-key operations.
> > >
> > > What actual problem is this fixing? To me it would seem like an
> > > enhancement to make the trusted module fail at load time if there's
> > > no TPM rather than waiting until first use to find out it can never
> > > work. Is there some piece of user code that depends on the
> > > successful insertion of trusted.ko?
> >
> > The module dependency chain relies on it. If that can be broken that
> > would also be an acceptable fix.
> >
> > I found this through the following dependency chain: libnvdimm.ko ->
> > encrypted_keys.ko -> trusted.ko.
> >
> > "key_type_trusted" is the symbol that encrypted_keys needs regardless
> > of whether the tpm is present.
>
> That's a nasty dependency caused by every key type module exporting a
> symbol for its key type. It really seems that key types should be
> looked up by name not symbol to prevent more of these dependency issues
> from spreading. Something like this (untested and definitely won't
> work without doing an EXPORT_SYMBOL on key_type_lookup).
>
> If it does look acceptable we can also disentangle the nasty module
> dependencies in the encrypted key code around masterkey which alone
> should be a huge improvement because that code is too hacky to live.
Looks good to me. I fired it up with the export added and also included a:
MODULE_SOFTDEP("pre: trusted");
...to encourage trusted.ko to be ready, if possible, for the lookup.
next prev parent reply other threads:[~2019-03-19 1:34 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-18 23:45 [PATCH] security/keys/trusted: Allow operation without hardware TPM Dan Williams
2019-03-19 0:24 ` James Bottomley
2019-03-19 0:30 ` Dan Williams
2019-03-19 0:56 ` James Bottomley
2019-03-19 1:34 ` Dan Williams [this message]
2019-03-20 1:55 ` Dan Williams
2019-03-20 2:19 ` James Bottomley
2019-03-19 22:56 ` Mimi Zohar
2019-03-19 23:01 ` Dan Williams
2019-03-21 13:54 ` Jarkko Sakkinen
2019-03-21 14:26 ` Roberto Sassu
2019-03-21 16:30 ` Dan Williams
2019-03-21 17:45 ` Roberto Sassu
2019-03-22 10:12 ` Jarkko Sakkinen
2019-03-22 15:24 ` Dan Williams
2019-03-25 14:12 ` Jarkko Sakkinen
2019-03-25 14:50 ` Jarkko Sakkinen
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