Messages in this thread | | | Subject | Re: [PATCH] KEYS: trusted: Fix trusted key backends when building as module | From | Ahmad Fatoum <> | Date | Mon, 19 Jul 2021 09:10:01 +0200 |
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Hello Andreas,
On 16.07.21 10:17, Andreas Rammhold wrote: > Before this commit the kernel could end up with no trusted key sources > even thought both of the currently supported backends (tpm & tee) were > compoiled as modules. This manifested in the trusted key type not being > registered at all.
I assume (TPM) trusted key module use worked before the TEE rework? If so,
an appropriate Fixes: Tag would then be in order.
> When checking if a CONFIG_… preprocessor variable is defined we only > test for the builtin (=y) case and not the module (=m) case. By using > the IS_ENABLE(…) macro we to test for both cases.
It looks to me like you could now provoke a link error if TEE is a module and built-in trusted key core tries to link against trusted_key_tee_ops.
One solution for that IS_REACHABLE(). Another is to address the root cause, which is the inflexible trusted keys Kconfig description:
- Trusted keys despite TEE support can still only be built when TCG_TPM is enabled - There is no support to have TEE or TPM enabled without using those for enabled trusted keys as well - As you noticed, module build of the backend has issues
I addressed these three issues in a patch[1], a month ago, but have yet to receive feedback.
[1]: https://lore.kernel.org/linux-integrity/f8285eb0135ba30c9d846cf9dd395d1f5f8b1efc.1624364386.git-series.a.fatoum@pengutronix.de/
Cheers, Ahmad
> Signed-off-by: Andreas Rammhold <andreas@rammhold.de> > --- > security/keys/trusted-keys/trusted_core.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/security/keys/trusted-keys/trusted_core.c b/security/keys/trusted-keys/trusted_core.c > index d5c891d8d353..fd640614b168 100644 > --- a/security/keys/trusted-keys/trusted_core.c > +++ b/security/keys/trusted-keys/trusted_core.c > @@ -27,10 +27,10 @@ module_param_named(source, trusted_key_source, charp, 0); > MODULE_PARM_DESC(source, "Select trusted keys source (tpm or tee)"); > > static const struct trusted_key_source trusted_key_sources[] = { > -#if defined(CONFIG_TCG_TPM) > +#if IS_ENABLED(CONFIG_TCG_TPM) > { "tpm", &trusted_key_tpm_ops }, > #endif > -#if defined(CONFIG_TEE) > +#if IS_ENABLED(CONFIG_TEE) > { "tee", &trusted_key_tee_ops }, > #endif > }; >
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