From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Garrett Subject: [PATCH 03/15] Secure boot: Add a dummy kernel parameter that will switch on Secure Boot mode Date: Mon, 28 Jan 2013 11:42:27 -0500 Message-ID: <1359391359-25783-4-git-send-email-matthew.garrett@nebula.com> References: <1359391359-25783-1-git-send-email-matthew.garrett@nebula.com> Return-path: In-Reply-To: <1359391359-25783-1-git-send-email-matthew.garrett-05XSO3Yj/JvQT0dZR+AlfA@public.gmane.org> Sender: linux-efi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-security-module-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Josh Boyer List-Id: linux-efi@vger.kernel.org From: Josh Boyer 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 --- Documentation/kernel-parameters.txt | 7 +++++++ kernel/cred.c | 17 +++++++++++++++++ 2 files changed, 24 insertions(+) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 363e348..832b39b 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -2654,6 +2654,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Note: increases power consumption, thus should only be enabled if running jitter sensitive (HPC/RT) workloads. + secureboot_enable= + [KNL] Enables an emulated UEFI Secure Boot mode. This + locks down various aspects of the kernel guarded by the + CAP_COMPROMISE_KERNEL capability. This includes things + like /dev/mem, IO port access, and other areas. It can + be used on non-UEFI machines for testing purposes. + security= [SECURITY] Choose a security module to enable at boot. If this boot parameter is not specified, only the first security module asking for security registration will be diff --git a/kernel/cred.c b/kernel/cred.c index e0573a4..c3f4e3e 100644 --- a/kernel/cred.c +++ b/kernel/cred.c @@ -565,6 +565,23 @@ 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 -- 1.8.0.2