From: "Lee, Chun-Yi" Subject: [PATCH 09/18] Secure boot: Add a dummy kernel parameter that will switch on Secure Boot mode Date: Thu, 22 Aug 2013 19:01:48 +0800 Message-ID: <1377169317-5959-10-git-send-email-jlee@suse.com> References: <1377169317-5959-1-git-send-email-jlee@suse.com> Cc: linux-security-module@vger.kernel.org, linux-efi@vger.kernel.org, linux-pm@vger.kernel.org, linux-crypto@vger.kernel.org, opensuse-kernel@opensuse.org, David Howells , "Rafael J. Wysocki" , Matthew Garrett , Len Brown , Pavel Machek , Josh Boyer , Vojtech Pavlik , Matt Fleming , James Bottomley , Greg KH , JKosina@suse.com, Rusty Russell , Herbert Xu , "David S. Miller" , "H. Peter Anvin" , Michal Marek , Gary Lin , Vivek Goyal , "Lee, Chun-Yi" To: linux-kernel@vger.kernel.org Return-path: In-Reply-To: <1377169317-5959-1-git-send-email-jlee@suse.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-crypto.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 Acked-by: Lee, Chun-Yi Signed-off-by: Lee, Chun-Yi --- Documentation/kernel-parameters.txt | 7 +++++++ kernel/cred.c | 17 +++++++++++++++++ 2 files changed, 24 insertions(+), 0 deletions(-) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 15356ac..6ad8292 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -2784,6 +2784,13 @@ 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 -- 1.6.4.2