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>,
Thomas Gleixner <tglx@linutronix.de>,
x86@kernel.org
Subject: [PATCH V36 13/29] x86/msr: Restrict MSR access when the kernel is locked down
Date: Thu, 18 Jul 2019 12:43:59 -0700 [thread overview]
Message-ID: <20190718194415.108476-14-matthewgarrett@google.com> (raw)
In-Reply-To: <20190718194415.108476-1-matthewgarrett@google.com>
From: Matthew Garrett <mjg59@srcf.ucam.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.
Signed-off-by: Matthew Garrett <mjg59@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
cc: x86@kernel.org
---
arch/x86/kernel/msr.c | 8 ++++++++
include/linux/security.h | 1 +
security/lockdown/lockdown.c | 1 +
3 files changed, 10 insertions(+)
diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c
index 3db2252b958d..1547be359d7f 100644
--- a/arch/x86/kernel/msr.c
+++ b/arch/x86/kernel/msr.c
@@ -34,6 +34,7 @@
#include <linux/notifier.h>
#include <linux/uaccess.h>
#include <linux/gfp.h>
+#include <linux/security.h>
#include <asm/cpufeature.h>
#include <asm/msr.h>
@@ -79,6 +80,10 @@ static ssize_t msr_write(struct file *file, const char __user *buf,
int err = 0;
ssize_t bytes = 0;
+ err = security_locked_down(LOCKDOWN_MSR);
+ if (err)
+ return err;
+
if (count % 8)
return -EINVAL; /* Invalid chunk size */
@@ -130,6 +135,9 @@ static long msr_ioctl(struct file *file, unsigned int ioc, unsigned long arg)
err = -EFAULT;
break;
}
+ err = security_locked_down(LOCKDOWN_MSR);
+ if (err)
+ break;
err = wrmsr_safe_regs_on_cpu(cpu, regs);
if (err)
break;
diff --git a/include/linux/security.h b/include/linux/security.h
index 79250b2ffb8f..155ff026eca4 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -109,6 +109,7 @@ enum lockdown_reason {
LOCKDOWN_HIBERNATION,
LOCKDOWN_PCI_ACCESS,
LOCKDOWN_IOPORT,
+ LOCKDOWN_MSR,
LOCKDOWN_INTEGRITY_MAX,
LOCKDOWN_CONFIDENTIALITY_MAX,
};
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 316f7cf4e996..d99c0bee739d 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -24,6 +24,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
[LOCKDOWN_HIBERNATION] = "hibernation",
[LOCKDOWN_PCI_ACCESS] = "direct PCI access",
[LOCKDOWN_IOPORT] = "raw io port access",
+ [LOCKDOWN_MSR] = "raw MSR access",
[LOCKDOWN_INTEGRITY_MAX] = "integrity",
[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
};
--
2.22.0.510.g264f2c817a-goog
next prev parent reply other threads:[~2019-07-18 19:45 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-18 19:43 [PATCH V36 00/29] security: Add kernel lockdown functionality Matthew Garrett
2019-07-18 19:43 ` [PATCH V36 01/29] security: Support early LSMs Matthew Garrett
2019-07-18 20:02 ` Casey Schaufler
2019-07-18 19:43 ` [PATCH V36 02/29] security: Add a "locked down" LSM hook Matthew Garrett
2019-07-18 20:03 ` Casey Schaufler
2019-07-18 19:43 ` [PATCH V36 03/29] security: Add a static lockdown policy LSM Matthew Garrett
2019-07-18 19:43 ` [PATCH V36 04/29] Enforce module signatures if the kernel is locked down Matthew Garrett
2019-07-18 19:43 ` [PATCH V36 05/29] Restrict /dev/{mem,kmem,port} when " Matthew Garrett
2019-07-18 19:43 ` [PATCH V36 06/29] kexec_load: Disable at runtime if " Matthew Garrett
2019-07-18 19:43 ` [PATCH V36 07/29] Copy secure_boot flag in boot params across kexec reboot Matthew Garrett
2019-07-18 19:43 ` [PATCH V36 08/29] kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE Matthew Garrett
2019-07-18 19:43 ` [PATCH V36 09/29] kexec_file: Restrict at runtime if the kernel is locked down Matthew Garrett
2019-07-18 19:43 ` [PATCH V36 10/29] hibernate: Disable when " Matthew Garrett
2019-07-18 19:43 ` [PATCH V36 11/29] PCI: Lock down BAR access " Matthew Garrett
2019-07-18 19:43 ` [PATCH V36 12/29] x86: Lock down IO port " Matthew Garrett
2019-07-18 19:43 ` Matthew Garrett [this message]
2019-07-18 19:44 ` [PATCH V36 14/29] ACPI: Limit access to custom_method " Matthew Garrett
2019-07-18 19:44 ` [PATCH V36 15/29] acpi: Ignore acpi_rsdp kernel param when the kernel has been " Matthew Garrett
2019-07-18 19:44 ` [PATCH V36 16/29] acpi: Disable ACPI table override if the kernel is " Matthew Garrett
2019-07-18 19:44 ` [PATCH V36 17/29] Prohibit PCMCIA CIS storage when " Matthew Garrett
2019-07-18 19:44 ` [PATCH V36 18/29] Lock down TIOCSSERIAL Matthew Garrett
2019-07-18 19:44 ` [PATCH V36 19/29] Lock down module params that specify hardware parameters (eg. ioport) Matthew Garrett
2019-07-29 21:47 ` Matthew Garrett
2019-07-18 19:44 ` [PATCH V36 20/29] x86/mmiotrace: Lock down the testmmiotrace module Matthew Garrett
2019-07-18 21:06 ` Kees Cook
2019-07-18 19:44 ` [PATCH V36 21/29] Lock down /proc/kcore Matthew Garrett
2019-07-18 19:44 ` [PATCH V36 22/29] Lock down tracing and perf kprobes when in confidentiality mode Matthew Garrett
2019-07-18 19:44 ` [PATCH V36 23/29] bpf: Restrict bpf when kernel lockdown is " Matthew Garrett
2019-07-18 21:06 ` Kees Cook
2019-07-29 21:47 ` Matthew Garrett
2019-07-18 19:44 ` [PATCH V36 24/29] Lock down perf when " Matthew Garrett
2019-07-18 19:44 ` [PATCH V36 25/29] kexec: Allow kexec_file() with appropriate IMA policy when locked down Matthew Garrett
2019-07-18 19:44 ` [PATCH V36 26/29] debugfs: Restrict debugfs when the kernel is " Matthew Garrett
2019-07-18 19:44 ` [PATCH V36 27/29] tracefs: Restrict tracefs " Matthew Garrett
2019-07-25 2:23 ` Steven Rostedt
2019-07-30 18:47 ` [PATCH] " Matthew Garrett
2019-07-31 1:48 ` Steven Rostedt
2019-07-18 19:44 ` [PATCH V36 28/29] efi: Restrict efivar_ssdt_load " Matthew Garrett
2019-07-18 19:44 ` [PATCH V36 29/29] lockdown: Print current->comm in restriction messages Matthew Garrett
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