[PATCH 10/10] kexec: update kexec_file_load syscall to call ima_kexec_post_load

[RuiRui Yang]

On Tue, 4 Jul 2023 at 05:58, Tushar Sugandhi
<tusharsu at linux.microsoft.com> wrote:
>
> The kexec_file_load syscall is used to load a new kernel for kexec.
> The syscall needs to update its function to call ima_kexec_post_load, which
> was implemented in a previous patch.  ima_kexec_post_load takes care of
> mapping the measurement list for the next kernel and registering a reboot
> notifier if it's not already registered.
>
> Modify the kexec_file_load syscall to call ima_kexec_post_load after the
> image has been loaded and prepared for kexec.  This ensures that the IMA
> measurement list will be available to the next kernel after a kexec reboot.
> This also ensures the measurements taken in the window between kexec load
> and execute are captured and passed to the next kernel.
>
> Declare the kimage_file_post_load function in the kernel/kexec_internal.h,
> so it can be properly used in the syscall.
>
> Signed-off-by: Tushar Sugandhi <tusharsu at linux.microsoft.com>
> ---
>  kernel/kexec_file.c     | 7 +++++++
>  kernel/kexec_internal.h | 1 +
>  2 files changed, 8 insertions(+)
>
> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index f989f5f1933b..efe28e77280c 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -184,6 +184,11 @@ kimage_validate_signature(struct kimage *image)
>  }
>  #endif
>
> +void kimage_file_post_load(struct kimage *image)
> +{
> +       ima_kexec_post_load(image);
> +}
> +
>  /*
>   * In file mode list of segments is prepared by kernel. Copy relevant
>   * data from user space, do error checking, prepare segment list
> @@ -399,6 +404,8 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
>
>         kimage_terminate(image);
>
> +       kimage_file_post_load(image);

I think it should be only done for the reboot case,  please just
exclude the kdump case here..

> +
>         ret = machine_kexec_post_load(image);
>         if (ret)
>                 goto out;
> diff --git a/kernel/kexec_internal.h b/kernel/kexec_internal.h
> index 74da1409cd14..98dd5fcafaf0 100644
> --- a/kernel/kexec_internal.h
> +++ b/kernel/kexec_internal.h
> @@ -30,6 +30,7 @@ static inline void kexec_unlock(void)
>
>  #ifdef CONFIG_KEXEC_FILE
>  #include <linux/purgatory.h>
> +void kimage_file_post_load(struct kimage *image);
>  void kimage_file_post_load_cleanup(struct kimage *image);
>  extern char kexec_purgatory[];
>  extern size_t kexec_purgatory_size;
> --
> 2.25.1
>
>
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