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,
Matthew Garrett <mjg59@srcf.ucam.org>,
Matthew Garrett <mjg59@google.com>,
David Howells <dhowells@redhat.com>,
Kees Cook <keescook@chromium.org>,
linux-acpi@vger.kernel.org
Subject: [PATCH V40 14/29] ACPI: Limit access to custom_method when the kernel is locked down
Date: Mon, 19 Aug 2019 17:17:50 -0700 [thread overview]
Message-ID: <20190820001805.241928-15-matthewgarrett@google.com> (raw)
In-Reply-To: <20190820001805.241928-1-matthewgarrett@google.com>
From: Matthew Garrett <mjg59@srcf.ucam.org>
custom_method effectively allows arbitrary access to system memory, making
it possible for an attacker to circumvent restrictions on module loading.
Disable it if the kernel is locked down.
Signed-off-by: Matthew Garrett <mjg59@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
cc: linux-acpi@vger.kernel.org
Signed-off-by: James Morris <jmorris@namei.org>
---
drivers/acpi/custom_method.c | 6 ++++++
include/linux/security.h | 1 +
security/lockdown/lockdown.c | 1 +
3 files changed, 8 insertions(+)
diff --git a/drivers/acpi/custom_method.c b/drivers/acpi/custom_method.c
index b2ef4c2ec955..7031307becd7 100644
--- a/drivers/acpi/custom_method.c
+++ b/drivers/acpi/custom_method.c
@@ -9,6 +9,7 @@
#include <linux/uaccess.h>
#include <linux/debugfs.h>
#include <linux/acpi.h>
+#include <linux/security.h>
#include "internal.h"
@@ -29,6 +30,11 @@ static ssize_t cm_write(struct file *file, const char __user * user_buf,
struct acpi_table_header table;
acpi_status status;
+ int ret;
+
+ ret = security_locked_down(LOCKDOWN_ACPI_TABLES);
+ if (ret)
+ return ret;
if (!(*ppos)) {
/* parse the table header to get the table length */
diff --git a/include/linux/security.h b/include/linux/security.h
index 010637a79eac..390e39395112 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -110,6 +110,7 @@ enum lockdown_reason {
LOCKDOWN_PCI_ACCESS,
LOCKDOWN_IOPORT,
LOCKDOWN_MSR,
+ LOCKDOWN_ACPI_TABLES,
LOCKDOWN_INTEGRITY_MAX,
LOCKDOWN_CONFIDENTIALITY_MAX,
};
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index b1c1c72440d5..6d44db0ddffa 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -25,6 +25,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
[LOCKDOWN_PCI_ACCESS] = "direct PCI access",
[LOCKDOWN_IOPORT] = "raw io port access",
[LOCKDOWN_MSR] = "raw MSR access",
+ [LOCKDOWN_ACPI_TABLES] = "modifying ACPI tables",
[LOCKDOWN_INTEGRITY_MAX] = "integrity",
[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
};
--
2.23.0.rc1.153.gdeed80330f-goog
next parent reply other threads:[~2019-08-20 0:20 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190820001805.241928-1-matthewgarrett@google.com>
2019-08-20 0:17 ` Matthew Garrett [this message]
2019-08-20 22:07 ` [PATCH V40 14/29] ACPI: Limit access to custom_method when the kernel is locked down Rafael J. Wysocki
2019-08-20 0:17 ` [PATCH V40 15/29] acpi: Ignore acpi_rsdp kernel param when the kernel has been " Matthew Garrett
2019-08-20 22:08 ` Rafael J. Wysocki
2019-08-20 0:17 ` [PATCH V40 16/29] acpi: Disable ACPI table override if the kernel is " Matthew Garrett
2019-08-20 22:08 ` Rafael J. Wysocki
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