Quoting Matthew Garrett (mjg@xxxxxxxxxx):
> From: Josh Boyer <jwboyer@xxxxxxxxxx>
>
> This forcibly drops CAP_COMPROMISE_KERNEL from both cap_permitted and cap_bset
> in the init_cred struct, which everything else inherits from. This works on
> any machine and can be used to develop even if the box doesn't have UEFI.
>
> Signed-off-by: Josh Boyer <jwboyer@xxxxxxxxxx>
Acked-by: Serge E. Hallyn <serge.hallyn@xxxxxxxxxx>
> ---
> kernel/cred.c | 17 +++++++++++++++++
> 1 file changed, 17 insertions(+)
>
> diff --git a/kernel/cred.c b/kernel/cred.c
> index de728ac..7e6e83f 100644
> --- a/kernel/cred.c
> +++ b/kernel/cred.c
> @@ -623,6 +623,23 @@ void __init cred_init(void)
> 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
> }
>
> +void __init secureboot_enable()
> +{
> + pr_info("Secure boot enabled\n");
> + cap_lower((&init_cred)->cap_bset, CAP_COMPROMISE_KERNEL);
> + cap_lower((&init_cred)->cap_permitted, CAP_COMPROMISE_KERNEL);
> +}
> +
> +/* Dummy Secure Boot enable option to fake out UEFI SB=1 */
> +static int __init secureboot_enable_opt(char *str)
> +{
> + int sb_enable = !!simple_strtol(str, NULL, 0);
> + if (sb_enable)
> + secureboot_enable();
> + return 1;
> +}
> +__setup("secureboot_enable=", secureboot_enable_opt);
> +
> /**
> * prepare_kernel_cred - Prepare a set of credentials for a kernel service
> * @daemon: A userspace daemon to be used as a reference
> --
> 1.7.11.4
>
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