From: David Howells <dhowells@redhat.com>
To: keyrings@vger.kernel.org
Cc: matthew.garrett@nebula.com, linux-efi@vger.kernel.org,
Kees Cook <keescook@chromium.org>,
linux-kernel@vger.kernel.org, dhowells@redhat.com,
linux-security-module@vger.kernel.org
Subject: [PATCH 16/16] x86: Restrict MSR access when the kernel is locked down
Date: Wed, 16 Nov 2016 21:49:12 +0000 [thread overview]
Message-ID: <147933295221.19316.10760767173988816147.stgit@warthog.procyon.org.uk> (raw)
In-Reply-To: <147933283664.19316.12454053022687659937.stgit@warthog.procyon.org.uk>
From: Matthew Garrett <matthew.garrett@nebula.com>
Writing to MSRs should not be allowed if the kernel is locked down, since
it could lead to execution of arbitrary code in kernel mode. Based on a
patch by Kees Cook.
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>
Signed-off-by: David Howells <dhowells@redhat.com>
---
arch/x86/kernel/msr.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c
index 7f3550acde1b..b875e54bdbf7 100644
--- a/arch/x86/kernel/msr.c
+++ b/arch/x86/kernel/msr.c
@@ -39,6 +39,7 @@
#include <linux/notifier.h>
#include <linux/uaccess.h>
#include <linux/gfp.h>
+#include <linux/security.h>
#include <asm/cpufeature.h>
#include <asm/msr.h>
@@ -83,6 +84,9 @@ static ssize_t msr_write(struct file *file, const char __user *buf,
int err = 0;
ssize_t bytes = 0;
+ if (kernel_is_locked_down())
+ return -EPERM;
+
if (count % 8)
return -EINVAL; /* Invalid chunk size */
@@ -130,6 +134,10 @@ static long msr_ioctl(struct file *file, unsigned int ioc, unsigned long arg)
err = -EBADF;
break;
}
+ if (kernel_is_locked_down()) {
+ err = -EPERM;
+ break;
+ }
if (copy_from_user(®s, uregs, sizeof regs)) {
err = -EFAULT;
break;
WARNING: multiple messages have this Message-ID (diff)
From: David Howells <dhowells-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
To: keyrings-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Cc: matthew.garrett-05XSO3Yj/JvQT0dZR+AlfA@public.gmane.org,
linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
dhowells-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org,
linux-security-module-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: [PATCH 16/16] x86: Restrict MSR access when the kernel is locked down
Date: Wed, 16 Nov 2016 21:49:12 +0000 [thread overview]
Message-ID: <147933295221.19316.10760767173988816147.stgit@warthog.procyon.org.uk> (raw)
In-Reply-To: <147933283664.19316.12454053022687659937.stgit-S6HVgzuS8uM4Awkfq6JHfwNdhmdF6hFW@public.gmane.org>
From: Matthew Garrett <matthew.garrett-05XSO3Yj/JvQT0dZR+AlfA@public.gmane.org>
Writing to MSRs should not be allowed if the kernel is locked down, since
it could lead to execution of arbitrary code in kernel mode. Based on a
patch by Kees Cook.
Cc: Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
Signed-off-by: Matthew Garrett <matthew.garrett-05XSO3Yj/JvQT0dZR+AlfA@public.gmane.org>
Signed-off-by: David Howells <dhowells-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
---
arch/x86/kernel/msr.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c
index 7f3550acde1b..b875e54bdbf7 100644
--- a/arch/x86/kernel/msr.c
+++ b/arch/x86/kernel/msr.c
@@ -39,6 +39,7 @@
#include <linux/notifier.h>
#include <linux/uaccess.h>
#include <linux/gfp.h>
+#include <linux/security.h>
#include <asm/cpufeature.h>
#include <asm/msr.h>
@@ -83,6 +84,9 @@ static ssize_t msr_write(struct file *file, const char __user *buf,
int err = 0;
ssize_t bytes = 0;
+ if (kernel_is_locked_down())
+ return -EPERM;
+
if (count % 8)
return -EINVAL; /* Invalid chunk size */
@@ -130,6 +134,10 @@ static long msr_ioctl(struct file *file, unsigned int ioc, unsigned long arg)
err = -EBADF;
break;
}
+ if (kernel_is_locked_down()) {
+ err = -EPERM;
+ break;
+ }
if (copy_from_user(®s, uregs, sizeof regs)) {
err = -EFAULT;
break;
next prev parent reply other threads:[~2016-11-16 21:49 UTC|newest]
Thread overview: 101+ 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 ` David Howells
2016-11-16 21:47 ` [PATCH 01/16] Add the ability to lock down access to the running kernel image David Howells
2016-11-16 22:20 ` Borislav Petkov
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 1/6] x86/efi: Allow invocation of arbitrary runtime services David Howells
2016-11-22 0:31 ` David Howells
2016-11-22 10:20 ` Lukas Wunner
2016-11-22 10:20 ` Lukas Wunner
2016-11-22 14:17 ` David Howells
2016-11-22 14:58 ` Joe Perches
2016-11-22 15:52 ` David Howells
2016-11-22 15:52 ` David Howells
2016-11-22 16:25 ` Joe Perches
2016-11-22 16:25 ` Joe Perches
2016-11-22 16:40 ` David Howells
2016-11-22 16:51 ` Joe Perches
2016-11-22 0:31 ` [PATCH 2/6] arm/efi: " 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
2016-11-22 10:49 ` Ard Biesheuvel
2016-11-22 10:49 ` Ard Biesheuvel
2016-11-22 14:47 ` David Howells
2016-11-22 20:30 ` Lukas Wunner
2016-11-23 0:02 ` David Howells
2016-11-22 14:52 ` David Howells
2016-11-22 14:52 ` David Howells
2016-11-22 20:36 ` Lukas Wunner
2016-11-22 20:36 ` Lukas Wunner
2016-11-22 14:57 ` David Howells
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 11:42 ` [PATCH 02/16] efi: Get the secure boot status David Howells
2016-11-21 11:42 ` David Howells
2016-11-21 11:52 ` Ard Biesheuvel
2016-11-21 11:52 ` Ard Biesheuvel
2016-11-21 12:41 ` David Howells
2016-11-21 12:41 ` David Howells
2016-11-21 13:14 ` Ard Biesheuvel
2016-11-21 15:17 ` Lukas Wunner
2016-11-21 15:17 ` Lukas Wunner
2016-11-21 15:25 ` Ard Biesheuvel
2016-11-21 11:46 ` David Howells
2016-11-21 19:58 ` Lukas Wunner
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 ` [PATCH 04/16] efi: Lock down the kernel if booted in secure boot mode David Howells
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
2016-11-18 12:10 ` Ard Biesheuvel
2016-11-18 12:10 ` Ard Biesheuvel
2016-11-18 17:28 ` David Howells
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
2016-11-16 21:48 ` [PATCH 11/16] x86: Lock down IO port " David Howells
2016-11-16 21:48 ` David Howells
2016-11-16 21:48 ` [PATCH 12/16] ACPI: Limit access to custom_method " 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 21:49 ` David Howells [this message]
2016-11-16 21:49 ` [PATCH 16/16] x86: Restrict MSR access when the kernel is " David Howells
2016-11-16 22:27 ` [PATCH 00/16] Kernel lockdown One Thousand Gnomes
2016-11-16 22:27 ` One Thousand Gnomes
2016-11-21 19:53 ` Ard Biesheuvel
2016-11-30 14:27 ` One Thousand Gnomes
2016-11-16 22:28 ` 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
2016-11-22 6:12 ` Dominik Brodowski
2016-11-23 12:58 ` David Howells
2016-11-23 19:21 ` Dominik Brodowski
2016-11-24 17:34 ` David Howells
2016-11-24 17:34 ` David Howells
2016-11-24 20:19 ` Dominik Brodowski
2016-11-25 14:49 ` David Howells
2016-11-28 22:32 ` Corey Minyard
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
2016-11-29 14:35 ` Corey Minyard
2016-11-29 14:35 ` Corey Minyard
2016-11-30 14:41 ` One Thousand Gnomes
2016-11-30 14:41 ` One Thousand Gnomes
2016-11-30 16:25 ` David Howells
2016-11-30 16:25 ` David Howells
2016-11-29 10:40 ` David Howells
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