Hi. Currently ima appraises all the files as specified by the rule. So if one wants to create a system where only few executables are signed, that system will not work with IMA.
With secureboot, one needs to disable kexec so that unsigned kernels can't be booted. To avoid this problem, it was proposed that sign /sbin/kexec binary and if signatures are verified successfully, give an special capability to the /sbin/kexec process. And in secureboot mode processes with that special capability can invoke sys_kexec() system call. So there is a need for IMA to allow appraising only signed binaries. Unsigned binaries will pass the appraisal too, but will not get the special capability. (Capability patches for that are yet to be written). This patch series adds new option, appraise_type=imasig_optional to allow appraisal to pass even if no signatures are present on the file. If signatures are present, then it has to be valid digital signature, otherwise appraisal will fail. v2: Changed patches based on Mimi's feedback. Thanks Vivek Vivek Goyal (2): ima: detect security xattrs not enabled ima: Allow appraisal of digitally signed files only Documentation/ABI/testing/ima_policy | 2 +- security/integrity/ima/ima_appraise.c | 27 +++++++++++++++++++++++---- security/integrity/ima/ima_policy.c | 2 ++ security/integrity/integrity.h | 1 + 4 files changed, 27 insertions(+), 5 deletions(-) -- 1.7.7.6 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
