From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Howells Subject: [PATCH 16/24] ACPI: Limit access to custom_method when the kernel is locked down Date: Wed, 05 Apr 2017 21:16:50 +0100 Message-ID: <149142340999.5101.7799938986753834830.stgit@warthog.procyon.org.uk> References: <149142326734.5101.4596394505987813763.stgit@warthog.procyon.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: Received: from mx1.redhat.com ([209.132.183.28]:42100 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934041AbdDEUQ6 (ORCPT ); Wed, 5 Apr 2017 16:16:58 -0400 In-Reply-To: <149142326734.5101.4596394505987813763.stgit@warthog.procyon.org.uk> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: linux-kernel@vger.kernel.org Cc: matthew.garrett@nebula.com, linux-efi@vger.kernel.org, gnomes@lxorguk.ukuu.org.uk, gregkh@linuxfoundation.org, dhowells@redhat.com, linux-acpi@vger.kernel.org, linux-security-module@vger.kernel.org, keyrings@vger.kernel.org From: Matthew Garrett 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 Signed-off-by: David Howells cc: linux-acpi@vger.kernel.org --- drivers/acpi/custom_method.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/acpi/custom_method.c b/drivers/acpi/custom_method.c index c68e72414a67..e4d721c330c0 100644 --- a/drivers/acpi/custom_method.c +++ b/drivers/acpi/custom_method.c @@ -29,6 +29,9 @@ static ssize_t cm_write(struct file *file, const char __user * user_buf, struct acpi_table_header table; acpi_status status; + if (kernel_is_locked_down()) + return -EPERM; + if (!(*ppos)) { /* parse the table header to get the table length */ if (count <= sizeof(struct acpi_table_header)) From mboxrd@z Thu Jan 1 00:00:00 1970 From: dhowells@redhat.com (David Howells) Date: Wed, 05 Apr 2017 21:16:50 +0100 Subject: [PATCH 16/24] ACPI: Limit access to custom_method when the kernel is locked down In-Reply-To: <149142326734.5101.4596394505987813763.stgit@warthog.procyon.org.uk> References: <149142326734.5101.4596394505987813763.stgit@warthog.procyon.org.uk> Message-ID: <149142340999.5101.7799938986753834830.stgit@warthog.procyon.org.uk> To: linux-security-module@vger.kernel.org List-Id: linux-security-module.vger.kernel.org From: Matthew Garrett 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 Signed-off-by: David Howells cc: linux-acpi at vger.kernel.org --- drivers/acpi/custom_method.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/acpi/custom_method.c b/drivers/acpi/custom_method.c index c68e72414a67..e4d721c330c0 100644 --- a/drivers/acpi/custom_method.c +++ b/drivers/acpi/custom_method.c @@ -29,6 +29,9 @@ static ssize_t cm_write(struct file *file, const char __user * user_buf, struct acpi_table_header table; acpi_status status; + if (kernel_is_locked_down()) + return -EPERM; + if (!(*ppos)) { /* parse the table header to get the table length */ if (count <= sizeof(struct acpi_table_header)) -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo at vger.kernel.org More majordomo info@ http://vger.kernel.org/majordomo-info.html