Re: [PATCH v4 1/3] kexec: clean up arch_kexec_kernel_verify_sig

From: Baoquan He
Date: Mon Mar 21 2022 - 00:21:50 EST


On 03/18/22 at 05:40pm, Coiby Xu wrote:
> Commit 9ec4ecef0af7 ("kexec_file,x86,powerpc: factor out kexec_file_ops
> functions") allows implementing the arch-specific implementation of kernel
> image verification in kexec_file_ops->verify_sig. Currently, there is no

Looking back at the old commit 9ec4ecef0af7, it mistakenly added a
generic arch_kexec_kernel_verify_sig() which is marked as __weak,
and expects any architecture will add a arch specified version if needed.
In fact those arch specified difference has been removed by wrapping
them into each architecture's own struct kexec_file_ops methods. Means
in the commit, the generic arch_kexec_kernel_verify_sig() is unnecessary
at all.

Now, you clean up that uncessary function with code change.

I think description telling above analysis could be clearer.

> arch-specific implementation of arch_kexec_kernel_verify_sig. So clean it
> up.
>
> Suggested-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
> Signed-off-by: Coiby Xu <coxu@xxxxxxxxxx>
> ---
> include/linux/kexec.h | 4 ----
> kernel/kexec_file.c | 34 +++++++++++++---------------------
> 2 files changed, 13 insertions(+), 25 deletions(-)
>
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index 0c994ae37729..755fed183224 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -196,10 +196,6 @@ int arch_kexec_apply_relocations(struct purgatory_info *pi,
> const Elf_Shdr *relsec,
> const Elf_Shdr *symtab);
> 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);
> -#endif
> int arch_kexec_locate_mem_hole(struct kexec_buf *kbuf);
>
> extern int kexec_add_buffer(struct kexec_buf *kbuf);
> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index 8347fc158d2b..3720435807eb 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -89,25 +89,6 @@ int __weak arch_kimage_file_post_load_cleanup(struct kimage *image)
> return kexec_image_post_load_cleanup_default(image);
> }
>
> -#ifdef CONFIG_KEXEC_SIG
> -static int kexec_image_verify_sig_default(struct kimage *image, void *buf,
> - unsigned long buf_len)
> -{
> - if (!image->fops || !image->fops->verify_sig) {
> - pr_debug("kernel loader does not support signature verification.\n");
> - return -EKEYREJECTED;
> - }
> -
> - return image->fops->verify_sig(buf, buf_len);
> -}
> -
> -int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
> - unsigned long buf_len)
> -{
> - return kexec_image_verify_sig_default(image, buf, buf_len);
> -}
> -#endif
> -
> /*
> * arch_kexec_apply_relocations_add - apply relocations of type RELA
> * @pi: Purgatory to be relocated.
> @@ -184,13 +165,24 @@ void kimage_file_post_load_cleanup(struct kimage *image)
> }
>
> #ifdef CONFIG_KEXEC_SIG
> +static int kexec_image_verify_sig(struct kimage *image, void *buf,
> + unsigned long buf_len)
> +{
> + if (!image->fops || !image->fops->verify_sig) {
> + pr_debug("kernel loader does not support signature verification.\n");
> + return -EKEYREJECTED;
> + }
> +
> + return image->fops->verify_sig(buf, buf_len);
> +}
> +
> static int
> kimage_validate_signature(struct kimage *image)
> {
> int ret;
>
> - ret = arch_kexec_kernel_verify_sig(image, image->kernel_buf,
> - image->kernel_buf_len);
> + ret = kexec_image_verify_sig(image, image->kernel_buf,
> + image->kernel_buf_len);
> if (ret) {
>
> if (IS_ENABLED(CONFIG_KEXEC_SIG_FORCE)) {
> --
> 2.34.1
>