On Tue, Dec 15, 2020 at 04:29:18PM +0800, Shan wrote:
> From: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
>
> 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@xxxxxxxxxxxxxxx
> Fixes: 240730437deb ("KEYS: trusted: explicitly use tpm_chip structure...")
> Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
> Reviewed-by: Tyler Hicks <tyhicks@xxxxxxxxxxxxx>
> Suggested-by: Mimi Zohar <zohar@xxxxxxxxxxxxx>
> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
>
> Signed-off-by: mayuanchen <mayuanchen@xxxxxxxx>
> Change-Id: Iada0e052c2ab4a0fbc2db4ac2690da3115d985c6
> Signed-off-by: Shan <chenshan@xxxxxxxx>
> ---
> 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
