On Tue, Dec 15, 2020 at 04:29:18PM +0800, Shan wrote:
From: Roberto Sassu roberto.sassu@huawei.com
commit 2d6c25215ab26bb009de3575faab7b685f138e92 upstream.
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
Signed-off-by: mayuanchen mayuanchen@hygon.cn Change-Id: Iada0e052c2ab4a0fbc2db4ac2690da3115d985c6 Signed-off-by: Shan chenshan@hygon.cn
security/keys/trusted.c | 13 ------------- 1 file changed, 13 deletions(-)
Why is this being sent to the stable list? Do you want this backported to 4.19.y? If so, why, and what is the change-id stuff in there for?
confused,
greg k-h