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Date: Fri, 22 Mar 2019 12:12:27 +0200 From: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com> To: Roberto Sassu <roberto.sassu@...wei.com> Cc: Dan Williams <dan.j.williams@...el.com>, James Bottomley <jejb@...ux.ibm.com>, Mimi Zohar <zohar@...ux.ibm.com>, David Howells <dhowells@...hat.com>, keyrings@...r.kernel.org, linux-nvdimm <linux-nvdimm@...ts.01.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Silviu Vlasceanu <Silviu.Vlasceanu@...wei.com> Subject: Re: [PATCH] security/keys/trusted: Allow operation without hardware TPM On Thu, Mar 21, 2019 at 06:45:47PM +0100, Roberto Sassu wrote: > On 3/21/2019 5:30 PM, Dan Williams wrote: > > On Thu, Mar 21, 2019 at 7:27 AM Roberto Sassu <roberto.sassu@...wei.com> wrote: > > > > > > On 3/21/2019 2:54 PM, Jarkko Sakkinen wrote: > > > > On Mon, Mar 18, 2019 at 04:45:13PM -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. > > > > > > > > > > Fixes: 240730437deb ("KEYS: trusted: explicitly use tpm_chip structure...") > > > > > Cc: Roberto Sassu <roberto.sassu@...wei.com> > > > > > Cc: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com> > > > > > Cc: James Bottomley <jejb@...ux.ibm.com> > > > > > Cc: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com> > > > > > Cc: Mimi Zohar <zohar@...ux.ibm.com> > > > > > Cc: David Howells <dhowells@...hat.com> > > > > > Signed-off-by: Dan Williams <dan.j.williams@...el.com> > > > > > > > > It should check for chip in each function that uses TPM now that > > > > the code does not rely on default chip. Otherwise, the semantics > > > > are kind of inconsistent. > > > > > > If no other TPM function can be used before a successful key > > > instantiate, checking for a chip only in trusted_instantiate() seems > > > sufficient. Then, the same chip will be used by all TPM functions until > > > module unloading, since we incremented the reference count. > > > > > > I would suggest to move the tpm_default_chip() and init_digests() calls > > > to trusted_instantiate() to restore the old behavior of init_trusted(). > > > > > > trusted_instantiate() should look like: > > > --- > > > if (!chip) { > > > chip = tpm_default_chip(); > > > if (!chip) > > > return -ENODEV; > > > } > > > > > > if (!digests) { > > > ret = init_digests(); > > > if (ret < 0) > > > return ret; > > > } > > > > This patch already achieves that because tpm_find_get_ops() will fail > > and cause tpm_is_tpm2() to return NULL. > > In addition, the changes I proposed would allow users to create trusted > keys if a TPM is added later. CONFIG_TRUSTED_KEYS=y and > CONFIG_TCG_TPM=m is a valid configuration. > > Jarkko, Dan's patch seems sufficient to fix the issue. He could include > the changes I proposed in his patch. What is your opinion? Agreed. /Jarkko
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