Re: [PATCH 09/24] kexec_file: Disable at runtime if securelevel has been set

[Dave Young]

On 04/05/17 at 09:15pm, David Howells wrote:
> From: Chun-Yi Lee <joeyli.kernel@xxxxxxxxx>
> 
> When KEXEC_VERIFY_SIG is not enabled, kernel should not loads image
> through kexec_file systemcall if securelevel has been set.
> 
> This code was showed in Matthew's patch but not in git:
> https://lkml.org/lkml/2015/3/13/778
> 
> Cc: Matthew Garrett <mjg59@xxxxxxxxxxxxx>
> Signed-off-by: Chun-Yi Lee <jlee@xxxxxxxx>
> Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
> cc: kexec@xxxxxxxxxxxxxxxxxxx
> ---
> 
>  kernel/kexec_file.c |    6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index b118735fea9d..f6937eecd1eb 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -268,6 +268,12 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
>  	if (!capable(CAP_SYS_BOOT) || kexec_load_disabled)
>  		return -EPERM;
>  
> +	/* Don't permit images to be loaded into trusted kernels if we're not
> +	 * going to verify the signature on them
> +	 */
> +	if (!IS_ENABLED(CONFIG_KEXEC_VERIFY_SIG) && kernel_is_locked_down())
> +		return -EPERM;
> +
>  	/* Make sure we have a legal set of flags */
>  	if (flags != (flags & KEXEC_FILE_FLAGS))
>  		return -EINVAL;
> 
> 
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Acked-by: Dave Young <dyoung@xxxxxxxxxx>

Thanks
Dave