On Thu, 2020-06-18 at 18:01 +0200, Roberto Sassu wrote:
> Public keys do not need to be appraised by IMA as the restriction on the
> IMA/EVM keyrings ensures that a key is loaded only if it is signed with a
> key in the primary or secondary keyring.
>
> However, when evm_load_x509() is loaded, appraisal is already enabled and
> a valid IMA signature must be added to the EVM key to pass verification.
>
> Since the restriction is applied on both IMA and EVM keyrings, it is safe
> to disable appraisal also when the EVM key is loaded. This patch calls
> evm_load_x509() inside ima_load_x509() if CONFIG_IMA_LOAD_X509 is defined.
>
> Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
> ---
> security/integrity/iint.c | 2 ++
> security/integrity/ima/ima_init.c | 4 ++++
> 2 files changed, 6 insertions(+)
>
> diff --git a/security/integrity/iint.c b/security/integrity/iint.c
> index e12c4900510f..4765a266ba96 100644
> --- a/security/integrity/iint.c
> +++ b/security/integrity/iint.c
> @@ -212,7 +212,9 @@ int integrity_kernel_read(struct file *file, loff_t offset,
> void __init integrity_load_keys(void)
> {
> ima_load_x509();
> +#ifndef CONFIG_IMA_LOAD_X509
> evm_load_x509();
> +#endif
> }
>
> static int __init integrity_fs_init(void)
> diff --git a/security/integrity/ima/ima_init.c b/security/integrity/ima/ima_init.c
> index 4902fe7bd570..9d29a1680da8 100644
> --- a/security/integrity/ima/ima_init.c
> +++ b/security/integrity/ima/ima_init.c
> @@ -106,6 +106,10 @@ void __init ima_load_x509(void)
>
> ima_policy_flag &= ~unset_flags;
> integrity_load_x509(INTEGRITY_KEYRING_IMA, CONFIG_IMA_X509_PATH);
> +
> + /* load also EVM key to avoid appraisal */
> + evm_load_x509();
> +
> ima_policy_flag |= unset_flags;
> }
> #endif
As much as possible IMA and EVM should remain independent of each
other. Modifying integrity_load_x509() doesn't help. This looks like
a good reason for calling another EVM function from within IMA.
Mimi
