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From: Matthew Garrett <matthewgarrett@google.com>
To: jmorris@namei.org
Cc: linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
	Linn Crosetto <lcrosetto@gmail.com>,
	David Howells <dhowells@redhat.com>,
	Matthew Garrett <mjg59@google.com>,
	Kees Cook <keescook@chromium.org>,
	linux-acpi@vger.kernel.org
Subject: [PATCH V38 16/29] acpi: Disable ACPI table override if the kernel is locked down
Date: Wed,  7 Aug 2019 17:07:08 -0700
Message-ID: <20190808000721.124691-17-matthewgarrett@google.com> (raw)
In-Reply-To: <20190808000721.124691-1-matthewgarrett@google.com>

From: Linn Crosetto <lcrosetto@gmail.com>

From the kernel documentation (initrd_table_override.txt):

  If the ACPI_INITRD_TABLE_OVERRIDE compile option is true, it is possible
  to override nearly any ACPI table provided by the BIOS with an
  instrumented, modified one.

When lockdown is enabled, the kernel should disallow any unauthenticated
changes to kernel space.  ACPI tables contain code invoked by the kernel,
so do not allow ACPI tables to be overridden if the kernel is locked down.

Signed-off-by: Linn Crosetto <lcrosetto@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
cc: linux-acpi@vger.kernel.org
---
 drivers/acpi/tables.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c
index b32327759380..180ac4329763 100644
--- a/drivers/acpi/tables.c
+++ b/drivers/acpi/tables.c
@@ -20,6 +20,7 @@
 #include <linux/memblock.h>
 #include <linux/earlycpio.h>
 #include <linux/initrd.h>
+#include <linux/security.h>
 #include "internal.h"
 
 #ifdef CONFIG_ACPI_CUSTOM_DSDT
@@ -578,6 +579,11 @@ void __init acpi_table_upgrade(void)
 	if (table_nr == 0)
 		return;
 
+	if (security_locked_down(LOCKDOWN_ACPI_TABLES)) {
+		pr_notice("kernel is locked down, ignoring table override\n");
+		return;
+	}
+
 	acpi_tables_addr =
 		memblock_find_in_range(0, ACPI_TABLE_UPGRADE_MAX_PHYS,
 				       all_tables_size, PAGE_SIZE);
-- 
2.22.0.770.g0f2c4a37fd-goog


  parent reply index

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-08  0:06 [PATCH V38 00/29] security: Add support for locking down the kernel Matthew Garrett
2019-08-08  0:06 ` [PATCH V38 01/29] security: Support early LSMs Matthew Garrett
2019-08-08  0:06 ` [PATCH V38 02/29] security: Add a "locked down" LSM hook Matthew Garrett
2019-08-08  0:06 ` [PATCH V38 03/29] security: Add a static lockdown policy LSM Matthew Garrett
2019-08-08  0:06 ` [PATCH V38 04/29] Enforce module signatures if the kernel is locked down Matthew Garrett
2019-08-08  0:06 ` [PATCH V38 05/29] Restrict /dev/{mem,kmem,port} when " Matthew Garrett
2019-08-08  0:06 ` [PATCH V38 06/29] kexec_load: Disable at runtime if " Matthew Garrett
2019-08-08  0:06 ` [PATCH V38 07/29] Copy secure_boot flag in boot params across kexec reboot Matthew Garrett
2019-08-08  0:07 ` [PATCH V38 08/29] kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE Matthew Garrett
2019-08-08  0:07 ` [PATCH V38 09/29] kexec_file: Restrict at runtime if the kernel is locked down Matthew Garrett
2019-08-08  0:07 ` [PATCH V38 10/29] hibernate: Disable when " Matthew Garrett
2019-08-08  0:07 ` [PATCH V38 11/29] PCI: Lock down BAR access " Matthew Garrett
2019-08-08  0:07 ` [PATCH V38 12/29] x86: Lock down IO port " Matthew Garrett
2019-08-08  0:07 ` [PATCH V38 13/29] x86/msr: Restrict MSR " Matthew Garrett
2019-08-08  0:07 ` [PATCH V38 14/29] ACPI: Limit access to custom_method " Matthew Garrett
2019-08-08  0:07 ` [PATCH V38 15/29] acpi: Ignore acpi_rsdp kernel param when the kernel has been " Matthew Garrett
2019-08-14  2:51   ` Dave Young
2019-08-14  7:26   ` Borislav Petkov
2019-08-14 17:14     ` Matthew Garrett
2019-08-14 17:47       ` Borislav Petkov
2019-08-14 18:02         ` Matthew Garrett
2019-08-14  7:28   ` Borislav Petkov
2019-08-08  0:07 ` Matthew Garrett [this message]
2019-08-08  0:07 ` [PATCH V38 17/29] Prohibit PCMCIA CIS storage when the kernel is " Matthew Garrett
2019-08-08  0:07 ` [PATCH V38 18/29] Lock down TIOCSSERIAL Matthew Garrett
2019-08-08  0:07 ` [PATCH V38 19/29] Lock down module params that specify hardware parameters (eg. ioport) Matthew Garrett
2019-08-08 11:12   ` Jessica Yu
2019-08-08 16:33     ` James Morris
2019-08-09 20:58     ` [PATCH V39] " Matthew Garrett
2019-08-08  0:07 ` [PATCH V38 20/29] x86/mmiotrace: Lock down the testmmiotrace module Matthew Garrett
2019-08-08  0:07 ` [PATCH V38 21/29] Lock down /proc/kcore Matthew Garrett
2019-08-08  0:07 ` [PATCH V38 22/29] Lock down tracing and perf kprobes when in confidentiality mode Matthew Garrett
2019-08-08  0:07 ` [PATCH V38 23/29] bpf: Restrict bpf when kernel lockdown is " Matthew Garrett
2019-08-08  0:07 ` [PATCH V38 24/29] Lock down perf when " Matthew Garrett
2019-08-08  0:07 ` [PATCH V38 25/29] kexec: Allow kexec_file() with appropriate IMA policy when locked down Matthew Garrett
2019-08-08  0:07 ` [PATCH V38 26/29] debugfs: Restrict debugfs when the kernel is " Matthew Garrett
2019-08-08  0:07 ` [PATCH V38 27/29] tracefs: Restrict tracefs " Matthew Garrett
2019-08-08  0:07 ` [PATCH V38 28/29] efi: Restrict efivar_ssdt_load " Matthew Garrett
2019-08-08  0:07 ` [PATCH V38 29/29] lockdown: Print current->comm in restriction messages Matthew Garrett
2019-08-10  6:08 ` [PATCH V38 00/29] security: Add support for locking down the kernel James Morris
2019-08-12 17:06   ` Matthew Garrett
2019-08-12 17:39     ` James Morris
2019-08-12 22:29       ` James Morris

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