]> git.proxmox.com Git - mirror_ubuntu-kernels.git/commit
KEYS: trusted: allow module init if TPM is inactive or deactivated
authorRoberto Sassu <roberto.sassu@huawei.com>
Mon, 5 Aug 2019 16:44:27 +0000 (18:44 +0200)
committerJarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Tue, 13 Aug 2019 16:59:23 +0000 (19:59 +0300)
commit2d6c25215ab26bb009de3575faab7b685f138e92
treec741ea6dc1f2b7040be70696eb10e3717aabdd3d
parentd45331b00ddb179e291766617259261c112db872
KEYS: trusted: allow module init if TPM is inactive or deactivated

Commit c78719203fc6 ("KEYS: trusted: allow trusted.ko to initialize w/o a
TPM") allows the trusted module to be loaded even if a TPM is not found, to
avoid module dependency problems.

However, trusted module initialization can still fail if the TPM is
inactive or deactivated. tpm_get_random() returns an error.

This patch removes the call to tpm_get_random() and instead extends the PCR
specified by the user with zeros. The security of this alternative is
equivalent to the previous one, as either option prevents with a PCR update
unsealing and misuse of sealed data by a user space process.

Even if a PCR is extended with zeros, instead of random data, it is still
computationally infeasible to find a value as input for a new PCR extend
operation, to obtain again the PCR value that would allow unsealing.

Cc: stable@vger.kernel.org
Fixes: 240730437deb ("KEYS: trusted: explicitly use tpm_chip structure...")
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Reviewed-by: Tyler Hicks <tyhicks@canonical.com>
Suggested-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
security/keys/trusted.c