> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
> index fddef8f8..8de40d85 100644
> --- a/security/integrity/ima/ima_policy.c
> +++ b/security/integrity/ima/ima_policy.c
> @@ -127,6 +127,7 @@ static struct ima_rule_entry default_measurement_rules[] __ro_after_init = {
> {.action = MEASURE, .func = MODULE_CHECK, .flags = IMA_FUNC},
> {.action = MEASURE, .func = FIRMWARE_CHECK, .flags = IMA_FUNC},
> {.action = MEASURE, .func = POLICY_CHECK, .flags = IMA_FUNC},
> + {.action = MEASURE, .fsmagic = FUSE_SUPER_MAGIC, .flags = IMA_FSMAGIC | IMA_FORCE},
> };
Depending on the ordering of the policies and the number of "actions",
this works. It also matches all hooks, not only those in the
default_measurement_rule policy.
Although the rules are walked sequentially, there is an optimization
in ima_match_rules(), which ends walking the list early, as soon as
the last "action" rule is matched. Look at "actmask".
> static struct ima_rule_entry default_appraise_rules[] __ro_after_init = {
> @@ -154,6 +155,7 @@ static struct ima_rule_entry default_appraise_rules[] __ro_after_init = {
> {.action = APPRAISE, .fowner = GLOBAL_ROOT_UID, .fowner_op = &uid_eq,
> .flags = IMA_FOWNER | IMA_DIGSIG_REQUIRED},
> #endif
> + {.action = APPRAISE, .fsmagic = FUSE_SUPER_MAGIC, .flags = IMA_FSMAGIC | IMA_FORCE},
> };
>
> static struct ima_rule_entry secure_boot_rules[] __ro_after_init = {
This rule applies to the secure-boot rules as well. (How likely is it
to load a kernel module, kexec from a fuse filsystem?) However, after
replacing the builtin policies with a custom policy, the custom policy
might not contain the requirement to re-appraise fuse files.
With the "lockdown" patches, booting with secure-boot enabled, and
after loading a custom policy, the "secure-boot" rules are still
enabled. But now if the custom policy does not require fuse files to
be re-appraised, the secure boot rules will not require fuse files to
be re-appraised either.
This patch is simple and straight forward. It would be nice if it
worked in all cases. Unfortunately, there are a number of situations,
as described, that will not work.
Mimi
