On 7/4/2019 12:42 PM, Jarkko Sakkinen wrote:
On Mon, 2019-07-01 at 17:22 +0300, Roberto Sassu wrote:
Adding to the discussion Jarkko (the maintainer of the trusted key) and
the linux-integrity mailing list.
I'm a co-maintainer (added James and Mimi).
some people (including me) have problems with the "trusted" kernel module.
As a result to this also the ecryptfs-module won't load.
(https://bugs.archlinux.org/task/62678)
If you use an "inactive" TPM module, the "trusted" module won't load
anymore.
The command modprobe just responds with "Bad address".
The strace-command shows that init_module fails with EFAULT.
I believe the reason for this is that the trusted-module handles
inactive modules the same as active modules.
This results in an error.
For example:
https://github.com/torvalds/linux/commit/0b6cf6b97b7ef1fa3c7fefab0cac897a1c4a3400#diff-c01228e6d386afb29df6aac17d9dd7abR1251
My guess is that init_digests(); returns EFAULT in that case.
The " if (!chip)" check above probably needs to check if the chip is
"inactive".
"inactive" = still visible to the system, but not functional.
It seems to be the default bios-setting for TPM on thinkpad.
(btw.: i have no clue why anybody would need something like that)
Sadly i have no idea how you would check for an inactive chip,else i
would have send a patch instead.
But I hope the info i wrote is enough to get it fixed by somebody.
Thanks for the report. If you see -EFAULT, tpm_get_random() is probably
returning 0.
Jarkko, we could consider it as non-critical error, and handle it as if
the TPM is not found. What do you think?
Not sure I get this. Wasn't the issue fixed in c78719203fc6 or is there
something missing?
It seems it is not enough. A TPM is found but does not return data to
tpm_get_random(), I think.
Roberto
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