From: Nathan Chancellor <nathan@kernel.org>
To: mike.malyshev@gmail.com
Cc: Nicolas Schier <nicolas.schier@linux.dev>,
Masahiro Yamada <masahiroy@kernel.org>,
linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] kbuild: Use objtree for module signing key path
Date: Wed, 15 Oct 2025 16:07:12 -0700 [thread overview]
Message-ID: <20251015230712.GA3943617@ax162> (raw)
In-Reply-To: <20251015163452.3754286-1-mike.malyshev@gmail.com>
On Wed, Oct 15, 2025 at 04:34:52PM +0000, mike.malyshev@gmail.com wrote:
> From: Mikhail Malyshev <mike.malyshev@gmail.com>
>
> When building out-of-tree modules with CONFIG_MODULE_SIG_FORCE=y,
> module signing fails because the private key path uses $(srctree)
> while the public key path uses $(objtree). Since signing keys are
> generated in the build directory during kernel compilation, both
> paths should use $(objtree) for consistency.
>
> This causes SSL errors like:
> SSL error:02001002:system library:fopen:No such file or directory
> sign-file: /kernel-src/certs/signing_key.pem
>
> The issue occurs because:
> - sig-key uses: $(srctree)/certs/signing_key.pem (source tree)
> - cmd_sign uses: $(objtree)/certs/signing_key.x509 (build tree)
>
> But both keys are generated in $(objtree) during the build.
>
> This complements commit 25ff08aa43e37 ("kbuild: Fix signing issue for
> external modules") which fixed the scripts path and public key path,
> but missed the private key path inconsistency.
>
> Fixes out-of-tree module signing for configurations with separate
> source and build directories (e.g., O=/kernel-out).
>
> Signed-off-by: Mikhail Malyshev <mike.malyshev@gmail.com>
Seems reasonable to me but I have not tested to verify.
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
> ---
> scripts/Makefile.modinst | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/scripts/Makefile.modinst b/scripts/Makefile.modinst
> index 1628198f3e830..9ba45e5b32b18 100644
> --- a/scripts/Makefile.modinst
> +++ b/scripts/Makefile.modinst
> @@ -100,7 +100,7 @@ endif
> # Don't stop modules_install even if we can't sign external modules.
> #
> ifeq ($(filter pkcs11:%, $(CONFIG_MODULE_SIG_KEY)),)
> -sig-key := $(if $(wildcard $(CONFIG_MODULE_SIG_KEY)),,$(srctree)/)$(CONFIG_MODULE_SIG_KEY)
> +sig-key := $(if $(wildcard $(CONFIG_MODULE_SIG_KEY)),,$(objtree)/)$(CONFIG_MODULE_SIG_KEY)
> else
> sig-key := $(CONFIG_MODULE_SIG_KEY)
> endif
> --
> 2.43.0
>
next prev parent reply other threads:[~2025-10-15 23:07 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-15 16:34 [PATCH] kbuild: Use objtree for module signing key path mike.malyshev
2025-10-15 19:08 ` Nicolas Schier
2025-10-15 23:07 ` Nathan Chancellor [this message]
2025-10-22 21:20 ` Nicolas Schier
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