linux-kernel - Re: [PATCH v6 3/4] arm64: kexec_file: use more system keyrings to verify kernel image signature

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Message-ID: <YlzJh8SE8pV1Et+O@MiWiFi-R3L-srv>
Date:   Mon, 18 Apr 2022 10:14:31 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Coiby Xu <coxu@...hat.com>
Cc:     kexec@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org,
        Michal Suchanek <msuchanek@...e.de>,
        Dave Young <dyoung@...hat.com>, Will Deacon <will@...nel.org>,
        "Eric W . Biederman" <ebiederm@...ssion.com>,
        Mimi Zohar <zohar@...ux.ibm.com>, Chun-Yi Lee <jlee@...e.com>,
        keyrings@...r.kernel.org, linux-security-module@...r.kernel.org,
        stable@...nel.org, Catalin Marinas <catalin.marinas@....com>,
        James Morse <james.morse@....com>,
        AKASHI Takahiro <takahiro.akashi@...aro.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v6 3/4] arm64: kexec_file: use more system keyrings to
 verify kernel image signature

On 04/14/22 at 09:43am, Coiby Xu wrote:
> Currently, a problem faced by arm64 is if a kernel image is signed by a
> MOK key, loading it via the kexec_file_load() system call would be
> rejected with the error "Lockdown: kexec: kexec of unsigned images is
> restricted; see man kernel_lockdown.7".
> 
> This happens because image_verify_sig uses only the primary keyring that
> contains only kernel built-in keys to verify the kexec image.
> 
> This patch allows to verify arm64 kernel image signature using not only
> .builtin_trusted_keys but also .platform and .secondary_trusted_keys
> keyring.
> 
> Fixes: 732b7b93d849 ("arm64: kexec_file: add kernel signature verification support")

Cc stable?

Otherwise, LGTM,

Acked-by: Baoquan He <bhe@...hat.com>

> Cc: kexec@...ts.infradead.org
> Cc: keyrings@...r.kernel.org
> Cc: linux-security-module@...r.kernel.org
> Cc: stable@...nel.org
> Co-developed-by: Michal Suchanek <msuchanek@...e.de>
> Signed-off-by: Michal Suchanek <msuchanek@...e.de>
> Acked-by: Will Deacon <will@...nel.org>
> Signed-off-by: Coiby Xu <coxu@...hat.com>
> ---
>  arch/arm64/kernel/kexec_image.c | 11 +----------
>  1 file changed, 1 insertion(+), 10 deletions(-)
> 
> diff --git a/arch/arm64/kernel/kexec_image.c b/arch/arm64/kernel/kexec_image.c
> index 9ec34690e255..5ed6a585f21f 100644
> --- a/arch/arm64/kernel/kexec_image.c
> +++ b/arch/arm64/kernel/kexec_image.c
> @@ -14,7 +14,6 @@
>  #include <linux/kexec.h>
>  #include <linux/pe.h>
>  #include <linux/string.h>
> -#include <linux/verification.h>
>  #include <asm/byteorder.h>
>  #include <asm/cpufeature.h>
>  #include <asm/image.h>
> @@ -130,18 +129,10 @@ static void *image_load(struct kimage *image,
>  	return NULL;
>  }
>  
> -#ifdef CONFIG_KEXEC_IMAGE_VERIFY_SIG
> -static int image_verify_sig(const char *kernel, unsigned long kernel_len)
> -{
> -	return verify_pefile_signature(kernel, kernel_len, NULL,
> -				       VERIFYING_KEXEC_PE_SIGNATURE);
> -}
> -#endif
> -
>  const struct kexec_file_ops kexec_image_ops = {
>  	.probe = image_probe,
>  	.load = image_load,
>  #ifdef CONFIG_KEXEC_IMAGE_VERIFY_SIG
> -	.verify_sig = image_verify_sig,
> +	.verify_sig = kexec_kernel_verify_pe_sig,
>  #endif
>  };
> -- 
> 2.34.1
> 
>