2021-06-29 22:06:21

by Stefan Berger

Subject: [PATCH v8 1/2] certs: Trigger creation of RSA module signing key if it's not an RSA key

From: Stefan Berger <[email protected]>

Address a kbuild issue where a developer created an ECDSA key for signing
kernel modules and then builds an older version of the kernel, when bi-
secting the kernel for example, that does not support ECDSA keys.

If openssl is installed, trigger the creation of an RSA module signing
key if it is not an RSA key.

Fixes: cfc411e7fff3 ("Move certificate handling to its own directory")
Cc: David Howells <[email protected]>
Cc: David Woodhouse <[email protected]>
Signed-off-by: Stefan Berger <[email protected]>
---
certs/Makefile | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/certs/Makefile b/certs/Makefile
index 359239a0ee9e..f9344e52ecda 100644
--- a/certs/Makefile
+++ b/certs/Makefile
@@ -57,11 +57,19 @@ endif
redirect_openssl = 2>&1
quiet_redirect_openssl = 2>&1
silent_redirect_openssl = 2>/dev/null
+openssl_available = $(shell openssl help 2>/dev/null && echo yes)

# We do it this way rather than having a boolean option for enabling an
# external private key, because 'make randconfig' might enable such a
# boolean option and we unfortunately can't make it depend on !RANDCONFIG.
ifeq ($(CONFIG_MODULE_SIG_KEY),"certs/signing_key.pem")
+
+ifeq ($(openssl_available),yes)
+X509TEXT=$(shell openssl x509 -in "certs/signing_key.pem" -text 2>/dev/null)
+
+$(if $(findstring rsaEncryption,$(X509TEXT)),,$(shell rm -f "certs/signing_key.pem"))
+endif
+
$(obj)/signing_key.pem: $(obj)/x509.genkey
@$(kecho) "###"
@$(kecho) "### Now generating an X.509 key pair to be used for signing modules."
--
2.31.1

2021-06-30 19:21:40

by Linus Torvalds

Subject: Re: [PATCH v8 1/2] certs: Trigger creation of RSA module signing key if it's not an RSA key

On Tue, Jun 29, 2021 at 2:34 PM Stefan Berger
<[email protected]> wrote:
>
> Address a kbuild issue where a developer created an ECDSA key for signing
> kernel modules and then builds an older version of the kernel, when bi-
> secting the kernel for example, that does not support ECDSA keys.

Thanks, these two don't confuse me any more.

Linus

2021-07-02 07:00:11

by Jarkko Sakkinen

Subject: Re: [PATCH v8 1/2] certs: Trigger creation of RSA module signing key if it's not an RSA key

On Wed, Jun 30, 2021 at 12:17:38PM -0700, Linus Torvalds wrote:
> On Tue, Jun 29, 2021 at 2:34 PM Stefan Berger
> <[email protected]> wrote:
> >
> > Address a kbuild issue where a developer created an ECDSA key for signing
> > kernel modules and then builds an older version of the kernel, when bi-
> > secting the kernel for example, that does not support ECDSA keys.
>
> Thanks, these two don't confuse me any more.
>
> Linus

I'll (re-)test the changes, and make a PR after rc1 out.

/Jarkko