Re: [PATCH] security/keys/trusted: Allow operation without hardware TPM

On Thu, Mar 21, 2019 at 7:27 AM Roberto Sassu <roberto.sassu(a)huawei.com&gt; 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(a)huawei.com&gt; >>> Cc: Jarkko Sakkinen <jarkko.sakkinen(a)linux.intel.com&gt; >>> Cc: James Bottomley <jejb(a)linux.ibm.com&gt; >>> Cc: Jarkko Sakkinen <jarkko.sakkinen(a)linux.intel.com&gt; >>> Cc: Mimi Zohar <zohar(a)linux.ibm.com&gt; >>> Cc: David Howells <dhowells(a)redhat.com&gt; >>> Signed-off-by: Dan Williams <dan.j.williams(a)intel.com&gt; >> >> 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.