Re: [PATCH 1/2] kexec, KEYS: make the code in bzImage64_verify_sig public

From: Dave Young
Date: Thu Sep 30 2021 - 08:50:19 EST


Hi Coiby,
On 09/27/21 at 08:50am, Coiby Xu wrote:
> From: Coiby Xu <coxu@xxxxxxxxxx>
>
> The code in bzImage64_verify_sig could make use of system keyrings including
> .buitin_trusted_keys, .secondary_trusted_keys and .platform keyring to verify
> signed kernel image as PE file. Move it to a public function.
>
> Signed-off-by: Coiby Xu <coiby.xu@xxxxxxxxx>
> ---
> arch/x86/kernel/kexec-bzimage64.c | 13 +------------
> include/linux/kexec.h | 3 +++
> kernel/kexec_file.c | 15 +++++++++++++++
> 3 files changed, 19 insertions(+), 12 deletions(-)
>
> diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
> index 170d0fd68b1f..4136dd3be5a9 100644
> --- a/arch/x86/kernel/kexec-bzimage64.c
> +++ b/arch/x86/kernel/kexec-bzimage64.c
> @@ -17,7 +17,6 @@
> #include <linux/kernel.h>
> #include <linux/mm.h>
> #include <linux/efi.h>
> -#include <linux/verification.h>
>
> #include <asm/bootparam.h>
> #include <asm/setup.h>
> @@ -531,17 +530,7 @@ static int bzImage64_cleanup(void *loader_data)
> #ifdef CONFIG_KEXEC_BZIMAGE_VERIFY_SIG
> static int bzImage64_verify_sig(const char *kernel, unsigned long kernel_len)
> {
> - int ret;
> -
> - ret = verify_pefile_signature(kernel, kernel_len,
> - VERIFY_USE_SECONDARY_KEYRING,
> - VERIFYING_KEXEC_PE_SIGNATURE);
> - if (ret == -ENOKEY && IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING)) {
> - ret = verify_pefile_signature(kernel, kernel_len,
> - VERIFY_USE_PLATFORM_KEYRING,
> - VERIFYING_KEXEC_PE_SIGNATURE);
> - }
> - return ret;
> + return arch_kexec_kernel_verify_pe_sig(kernel, kernel_len);
> }
> #endif
>
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index 0c994ae37729..d45f32336dbe 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -19,6 +19,7 @@
> #include <asm/io.h>
>
> #include <uapi/linux/kexec.h>
> +#include <linux/verification.h>
>
> #ifdef CONFIG_KEXEC_CORE
> #include <linux/list.h>
> @@ -199,6 +200,8 @@ int arch_kimage_file_post_load_cleanup(struct kimage *image);
> #ifdef CONFIG_KEXEC_SIG
> int arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
> unsigned long buf_len);
> +int arch_kexec_kernel_verify_pe_sig(const char *kernel,
> + unsigned long kernel_len);
> #endif
> int arch_kexec_locate_mem_hole(struct kexec_buf *kbuf);
>
> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index 33400ff051a8..85ed6984ad8f 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -106,6 +106,21 @@ int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
> {
> return kexec_image_verify_sig_default(image, buf, buf_len);
> }
> +
> +int arch_kexec_kernel_verify_pe_sig(const char *kernel, unsigned long kernel_len)
> +{
> + int ret;
> +
> + ret = verify_pefile_signature(kernel, kernel_len,
> + VERIFY_USE_SECONDARY_KEYRING,
> + VERIFYING_KEXEC_PE_SIGNATURE);
> + if (ret == -ENOKEY && IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING)) {
> + ret = verify_pefile_signature(kernel, kernel_len,
> + VERIFY_USE_PLATFORM_KEYRING,
> + VERIFYING_KEXEC_PE_SIGNATURE);
> + }
> + return ret;
> +}

Since the function is moved as generic code, the kconfig option
CONFIG_KEXEC_BZIMAGE_VERIFY_SIG can be removed.

Instead a CONFIG_KEXEC_PEFILE_VERIFY_SIG can be added so that it does
not need to be compiled for only platform which support UEFI pefile
signature verification. And the related arch kexec_file kconfig can
just select it.

Coiby, can you try above?

> #endif
>
> /*
> --
> 2.33.0
>
>
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>
>

Thanks
Dave