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 V37 13/29] x86/msr: Restrict MSR access when the kernel is locked down
Date: Wed, 31 Jul 2019 15:16:01 -0700 [thread overview]
Message-ID: <20190731221617.234725-14-matthewgarrett@google.com> (raw)
In-Reply-To: <20190731221617.234725-1-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",
};
--
2.22.0.770.g0f2c4a37fd-goog
next prev parent reply other threads:[~2019-07-31 22:19 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-31 22:15 [PATCH V37 00/29] security: Add support for locking down the kernel Matthew Garrett
2019-07-31 22:15 ` [PATCH V37 01/29] security: Support early LSMs Matthew Garrett
2019-07-31 22:15 ` [PATCH V37 02/29] security: Add a "locked down" LSM hook Matthew Garrett
2019-07-31 22:15 ` [PATCH V37 03/29] security: Add a static lockdown policy LSM Matthew Garrett
2019-07-31 22:15 ` [PATCH V37 04/29] Enforce module signatures if the kernel is locked down Matthew Garrett
2019-08-01 14:21 ` Jessica Yu
2019-08-01 20:42 ` Matthew Garrett
2019-08-08 10:01 ` Jessica Yu
2019-08-08 18:31 ` Matthew Garrett
2019-08-08 22:43 ` James Morris
2019-08-09 20:59 ` [PATCH V39] " Matthew Garrett
2019-07-31 22:15 ` [PATCH V37 05/29] Restrict /dev/{mem,kmem,port} when " Matthew Garrett
2019-07-31 22:15 ` [PATCH V37 06/29] kexec_load: Disable at runtime if " Matthew Garrett
2019-07-31 22:15 ` [PATCH V37 07/29] Copy secure_boot flag in boot params across kexec reboot Matthew Garrett
2019-07-31 22:15 ` [PATCH V37 08/29] kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE Matthew Garrett
2019-07-31 22:15 ` [PATCH V37 09/29] kexec_file: Restrict at runtime if the kernel is locked down Matthew Garrett
2019-07-31 22:15 ` [PATCH V37 10/29] hibernate: Disable when " Matthew Garrett
2019-07-31 22:15 ` [PATCH V37 11/29] PCI: Lock down BAR access " Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 12/29] x86: Lock down IO port " Matthew Garrett
2019-07-31 22:16 ` Matthew Garrett [this message]
2019-07-31 22:16 ` [PATCH V37 14/29] ACPI: Limit access to custom_method " Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 15/29] acpi: Ignore acpi_rsdp kernel param when the kernel has been " Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 16/29] acpi: Disable ACPI table override if the kernel is " Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 17/29] Prohibit PCMCIA CIS storage when " Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 18/29] Lock down TIOCSSERIAL Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 19/29] Lock down module params that specify hardware parameters (eg. ioport) Matthew Garrett
2019-08-01 16:19 ` Jessica Yu
2019-08-01 20:44 ` Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 20/29] x86/mmiotrace: Lock down the testmmiotrace module Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 21/29] Lock down /proc/kcore Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 22/29] Lock down tracing and perf kprobes when in confidentiality mode Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 23/29] bpf: Restrict bpf when kernel lockdown is " Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 24/29] Lock down perf when " Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 25/29] kexec: Allow kexec_file() with appropriate IMA policy when locked down Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 26/29] debugfs: Restrict debugfs when the kernel is " Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 27/29] tracefs: Restrict tracefs " Matthew Garrett
[not found] ` <CGME20190813061053eucas1p1b6945259d9663b743e7cb32521d041e7@eucas1p1.samsung.com>
2019-08-13 6:10 ` Marek Szyprowski
[not found] ` <CGME20190813072111eucas1p2b87f3f8d16c22a0a3d024bc5ebcc8bcc@eucas1p2.samsung.com>
2019-08-13 7:21 ` Marek Szyprowski
[not found] ` <CGME20190814061246eucas1p128cae99a14f27bc79fa2aa72084a0413@eucas1p1.samsung.com>
2019-08-14 6:12 ` [PATCH] tracefs: Fix NULL pointer dereference when no lockdown is used Marek Szyprowski
2019-07-31 22:16 ` [PATCH V37 28/29] efi: Restrict efivar_ssdt_load when the kernel is locked down Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 29/29] lockdown: Print current->comm in restriction messages Matthew Garrett
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