Linux-EFI Archive on lore.kernel.org
 help / color / Atom feed
From: David Howells <dhowells@redhat.com>
To: keyrings@vger.kernel.org
Cc: dhowells@redhat.com, matthew.garrett@nebula.com,
	linux-security-module@vger.kernel.org, linux-efi@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH 04/16] efi: Lock down the kernel if booted in secure boot mode
Date: Wed, 16 Nov 2016 21:47:45 +0000
Message-ID: <147933286579.19316.5236862894522647474.stgit@warthog.procyon.org.uk> (raw)
In-Reply-To: <147933283664.19316.12454053022687659937.stgit@warthog.procyon.org.uk>

UEFI Secure Boot provides a mechanism for ensuring that the firmware will
only load signed bootloaders and kernels.  Certain use cases may also
require that all kernel modules also be signed.  Add a configuration option
that to lock down the kernel - which includes requiring validly signed
modules - if the kernel is secure-booted.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 arch/x86/Kconfig        |   12 ++++++++++++
 arch/x86/kernel/setup.c |    7 +++++++
 kernel/module.c         |    2 +-
 3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index bada636d1065..5b19997d88d0 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1786,6 +1786,18 @@ config EFI_MIXED
 
 	   If unsure, say N.
 
+config EFI_SECURE_BOOT_LOCK_DOWN
+	def_bool n
+	depends on EFI
+	prompt "Lock down the kernel when UEFI Secure Boot is enabled"
+	---help---
+	  UEFI Secure Boot provides a mechanism for ensuring that the firmware
+	  will only load signed bootloaders and kernels.  Certain use cases may
+	  also require that all kernel modules also be signed and that
+	  userspace is prevented from directly changing the running kernel
+	  image.  Say Y here to automatically lock down the kernel when a
+	  system boots with UEFI Secure Boot enabled.
+
 config SECCOMP
 	def_bool y
 	prompt "Enable seccomp to safely compute untrusted bytecode"
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 9c337b0e8ba7..9521acce8378 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -69,6 +69,7 @@
 #include <linux/crash_dump.h>
 #include <linux/tboot.h>
 #include <linux/jiffies.h>
+#include <linux/security.h>
 
 #include <video/edid.h>
 
@@ -1160,6 +1161,12 @@ void __init setup_arch(char **cmdline_p)
 
 	io_delay_init();
 
+	if (boot_params.secure_boot &&
+	    IS_ENABLED(CONFIG_EFI_SECURE_BOOT_LOCK_DOWN)) {
+		lock_kernel_down();
+		pr_info("Secure boot enabled\n");
+	}
+
 	/*
 	 * Parse the ACPI tables for possible boot-time SMP configuration.
 	 */
diff --git a/kernel/module.c b/kernel/module.c
index f57dd63186e6..2a021c340efd 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2744,7 +2744,7 @@ static int module_sig_check(struct load_info *info, int flags)
 	}
 
 	/* Not having a signature is only an error if we're strict. */
-	if (err == -ENOKEY && !sig_enforce)
+	if (err == -ENOKEY && !sig_enforce && !kernel_is_locked_down())
 		err = 0;
 
 	return err;


  parent reply index

Thread overview: 76+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-11-16 21:47 [PATCH 00/16] Kernel lockdown David Howells
2016-11-16 21:47 ` [PATCH 01/16] Add the ability to lock down access to the running kernel image David Howells
     [not found]   ` <147933284407.19316.17886320817060158597.stgit-S6HVgzuS8uM4Awkfq6JHfwNdhmdF6hFW@public.gmane.org>
2016-11-16 22:20     ` Borislav Petkov
2016-11-16 22:40   ` David Howells
2016-12-25 21:20   ` Pavel Machek
2016-12-25 21:44   ` David Howells
2016-11-16 21:47 ` [PATCH 02/16] efi: Get the secure boot status David Howells
2016-11-17 12:37   ` Lukas Wunner
2016-11-22  0:31     ` [PATCH 2/6] arm/efi: Allow invocation of arbitrary runtime services David Howells
2016-11-22  0:31     ` [PATCH 3/6] efi: Add SHIM and image security database GUID definitions David Howells
2016-11-22  0:32     ` [PATCH 4/6] efi: Get the secure boot status David Howells
2016-11-22 10:44       ` Lukas Wunner
     [not found]         ` <20161122104401.GC1552-JFq808J9C/izQB+pC5nmwQ@public.gmane.org>
2016-11-22 10:49           ` Ard Biesheuvel
2016-11-22 14:52           ` David Howells
     [not found]             ` <25371.1479826321-S6HVgzuS8uM4Awkfq6JHfwNdhmdF6hFW@public.gmane.org>
2016-11-22 20:36               ` Lukas Wunner
2016-11-22 14:47       ` David Howells
2016-11-22 20:30         ` Lukas Wunner
2016-11-23  0:02         ` David Howells
     [not found]       ` <7199.1479826047-S6HVgzuS8uM4Awkfq6JHfwNdhmdF6hFW@public.gmane.org>
2016-11-22 14:57         ` David Howells
2016-11-22  0:32     ` [PATCH 5/6] efi: Disable secure boot if shim is in insecure mode David Howells
2016-11-22 13:03       ` Lukas Wunner
2016-11-22  0:32     ` [PATCH 6/6] efi: Add EFI_SECURE_BOOT bit David Howells
2016-11-22 13:04       ` Lukas Wunner
2016-11-21 11:46   ` [PATCH 02/16] efi: Get the secure boot status David Howells
2016-11-21 19:58     ` Lukas Wunner
     [not found]   ` <20161117123731.GA11573-JFq808J9C/izQB+pC5nmwQ@public.gmane.org>
2016-11-21 11:42     ` David Howells
     [not found]       ` <29779.1479728545-S6HVgzuS8uM4Awkfq6JHfwNdhmdF6hFW@public.gmane.org>
2016-11-21 11:52         ` Ard Biesheuvel
     [not found]       ` <CAKv+Gu-frVDhzORDRZ6XT+FxewsTgrxhXmM=DqaS6Ns4mJhQ9g-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-11-21 12:41         ` David Howells
2016-11-21 13:14           ` Ard Biesheuvel
     [not found]             ` <CAKv+Gu8Lhm=u97hY1y+Y+Ladk=y7pSVNrow8ML1hQUJ9+74B-w-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-11-21 15:17               ` Lukas Wunner
2016-11-21 15:25                 ` Ard Biesheuvel
2016-11-22  0:31     ` [PATCH 1/6] x86/efi: Allow invocation of arbitrary runtime services David Howells
     [not found]       ` <147977469914.6360.17194649697208113702.stgit-S6HVgzuS8uM4Awkfq6JHfwNdhmdF6hFW@public.gmane.org>
2016-11-22 10:20         ` Lukas Wunner
2016-11-22 14:17       ` David Howells
2016-11-22 14:58         ` Joe Perches
     [not found]         ` <1479826691.1942.11.camel-6d6DIl74uiNBDgjK7y7TUQ@public.gmane.org>
2016-11-22 15:52           ` David Howells
     [not found]             ` <24973.1479829961-S6HVgzuS8uM4Awkfq6JHfwNdhmdF6hFW@public.gmane.org>
2016-11-22 16:25               ` Joe Perches
2016-11-22 16:40             ` David Howells
2016-11-22 16:51               ` Joe Perches
2016-11-16 21:47 ` [PATCH 03/16] efi: Disable secure boot if shim is in insecure mode David Howells
2016-11-16 21:47 ` David Howells [this message]
2016-11-16 21:47 ` [PATCH 05/16] efi: Add EFI_SECURE_BOOT bit David Howells
2016-11-17 21:58   ` Ard Biesheuvel
2016-11-18 11:58     ` Josh Boyer
     [not found]       ` <CA+5PVA6F5qEnuL2UaXS9_fJ217J93cEZDDsz9Y2BPwHXcMdX-A-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-11-18 12:10         ` Ard Biesheuvel
     [not found]   ` <CAKv+Gu_8r3oM-jvvuSiXTzxp0YMEVgc5KkScJ2UhGTaXm28L6w-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-11-18 17:28     ` David Howells
2016-11-16 21:48 ` [PATCH 06/16] Add a sysrq option to exit secure boot mode David Howells
2016-11-16 21:48 ` [PATCH 07/16] kexec: Disable at runtime if the kernel is locked down David Howells
2016-11-16 21:48 ` [PATCH 08/16] Copy secure_boot flag in boot params across kexec reboot David Howells
2016-11-16 21:48 ` [PATCH 09/16] hibernate: Disable when the kernel is locked down David Howells
2016-11-16 21:48 ` [PATCH 10/16] PCI: Lock down BAR access " David Howells
     [not found] ` <147933283664.19316.12454053022687659937.stgit-S6HVgzuS8uM4Awkfq6JHfwNdhmdF6hFW@public.gmane.org>
2016-11-16 21:48   ` [PATCH 11/16] x86: Lock down IO port " David Howells
2016-11-16 21:49   ` [PATCH 16/16] x86: Restrict MSR " David Howells
2016-11-16 22:27   ` [PATCH 00/16] Kernel lockdown One Thousand Gnomes
2016-11-21 19:53     ` Ard Biesheuvel
2016-11-30 14:27       ` One Thousand Gnomes
2016-11-16 21:48 ` [PATCH 12/16] ACPI: Limit access to custom_method when the kernel is locked down David Howells
2016-11-16 21:48 ` [PATCH 13/16] asus-wmi: Restrict debugfs interface " David Howells
2016-11-16 21:48 ` [PATCH 14/16] Restrict /dev/mem and /dev/kmem " David Howells
2016-11-16 21:49 ` [PATCH 15/16] acpi: Ignore acpi_rsdp kernel param when the kernel has been " David Howells
2016-11-16 22:28 ` [PATCH 00/16] Kernel lockdown Justin Forbes
2016-11-21 23:10 ` [PATCH] Lock down drivers that can have io ports, io mem, irqs and dma changed David Howells
2016-11-22  6:12   ` Dominik Brodowski
2016-11-23 12:58   ` David Howells
2016-11-23 19:21     ` Dominik Brodowski
     [not found]     ` <20161123192143.GA482-SGhQLRGLuNwb6pqDj42GsMgv3T4z79SOrE5yTffgRl4@public.gmane.org>
2016-11-24 17:34       ` David Howells
2016-11-24 20:19         ` Dominik Brodowski
2016-11-25 14:49         ` David Howells
     [not found]   ` <26173.1479769852-S6HVgzuS8uM4Awkfq6JHfwNdhmdF6hFW@public.gmane.org>
2016-11-28 22:32     ` Corey Minyard
2016-11-29  0:11   ` David Howells
2016-11-29  0:23     ` Corey Minyard
2016-11-29 14:03     ` David Howells
     [not found]       ` <6973.1480428211-S6HVgzuS8uM4Awkfq6JHfwNdhmdF6hFW@public.gmane.org>
2016-11-29 14:35         ` Corey Minyard
2016-11-30 14:41         ` One Thousand Gnomes
     [not found]       ` <20161130144105.2b6be4fe-qBU/x9rampVanCEyBjwyrvXRex20P6io@public.gmane.org>
2016-11-30 16:25         ` David Howells
2016-11-29 10:40   ` David Howells

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=147933286579.19316.5236862894522647474.stgit@warthog.procyon.org.uk \
    --to=dhowells@redhat.com \
    --cc=keyrings@vger.kernel.org \
    --cc=linux-efi@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-security-module@vger.kernel.org \
    --cc=matthew.garrett@nebula.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-EFI Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-efi/0 linux-efi/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-efi linux-efi/ https://lore.kernel.org/linux-efi \
		linux-efi@vger.kernel.org
	public-inbox-index linux-efi

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-efi


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git