Hi Thiago,


On Thu, 04 Jul 2019 03:42:57 -0300
Thiago Jung Bauermann [off-list ref] wrote:

Jessica Yu [off-list ref] writes:

quoted

+++ Thiago Jung Bauermann [27/06/19 23:19 -0300]:  

quoted

IMA will use the module_signature format for append signatures, so export
the relevant definitions and factor out the code which verifies that the
appended signature trailer is valid.

Also, create a CONFIG_MODULE_SIG_FORMAT option so that IMA can select it
and be able to use mod_check_sig() without having to depend on either
CONFIG_MODULE_SIG or CONFIG_MODULES.

Signed-off-by: Thiago Jung Bauermann <redacted>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Cc: Jessica Yu <jeyu@kernel.org>
---
include/linux/module.h           |  3 --
include/linux/module_signature.h | 44 +++++++++++++++++++++++++
init/Kconfig                     |  6 +++-
kernel/Makefile                  |  1 +
kernel/module.c                  |  1 +
kernel/module_signature.c        | 46 ++++++++++++++++++++++++++
kernel/module_signing.c          | 56 +++++---------------------------
scripts/Makefile                 |  2 +-
8 files changed, 106 insertions(+), 53 deletions(-)

diff --git a/include/linux/module.h b/include/linux/module.h
index 188998d3dca9..aa56f531cf1e 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h

@@ -25,9 +25,6 @@

#include <linux/percpu.h>
#include <asm/module.h>

-/* In stripped ARM and x86-64 modules, ~ is surprisingly rare. */
-#define MODULE_SIG_STRING "~Module signature appended~\n"
-  

Hi Thiago, apologies for the delay.  

Hello Jessica, thanks for reviewing the patch!

quoted

It looks like arch/s390/kernel/machine_kexec_file.c also relies on
MODULE_SIG_STRING being defined, so module_signature.h will need to be
included there too, otherwise we'll run into a compilation error.  

Indeed. Thanks for spotting that. The patch below fixes it. It's
identical to the previous version except for the changes in 
arch/s390/kernel/machine_kexec_file.c and their description in the
commit message. I'm also copying some s390 people in this email.

to me the s390 part looks good but for one minor nit.

In arch/s390/Kconfig KEXEC_VERIFY_SIG currently depends on
SYSTEM_DATA_VERIFICATION. I'd prefer when you update this to the new
MODULE_SIG_FORMAT. It shouldn't make any difference right now, as we don't
use mod_check_sig in our code path. But it could cause problems in the future,
when more code might be shared.

Thanks
Philipp

quoted

Other than that, the module-related changes look good to me:

Acked-by: Jessica Yu <jeyu@kernel.org>  

Thank you very much!