From: Matthew Garrett <matthewgarrett@google.com>
To: jmorris@namei.org
Cc: linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org, dhowells@redhat.com
Subject: [PATCH 13/27] x86/msr: Restrict MSR access when the kernel is locked down
Date: Thu, 28 Feb 2019 15:11:49 -0800 [thread overview]
Message-ID: <20190228231203.212359-13-matthewgarrett@google.com> (raw)
In-Reply-To: <20190228231203.212359-1-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.
MSR accesses are logged for the purposes of building up a whitelist as per
Alan Cox's suggestion.
Signed-off-by: Matthew Garrett <mjg59@srcf.ucam.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: "Lee, Chun-Yi" <jlee@suse.com>
cc: x86@kernel.org
---
arch/x86/kernel/msr.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c
index 4588414e2561..f5a2cf07972f 100644
--- a/arch/x86/kernel/msr.c
+++ b/arch/x86/kernel/msr.c
@@ -84,6 +84,11 @@ static ssize_t msr_write(struct file *file, const char __user *buf,
int err = 0;
ssize_t bytes = 0;
+ if (kernel_is_locked_down("Direct MSR access")) {
+ pr_info("Direct access to MSR %x\n", reg);
+ return -EPERM;
+ }
+
if (count % 8)
return -EINVAL; /* Invalid chunk size */
@@ -135,6 +140,11 @@ static long msr_ioctl(struct file *file, unsigned int ioc, unsigned long arg)
err = -EFAULT;
break;
}
+ if (kernel_is_locked_down("Direct MSR access")) {
+ pr_info("Direct access to MSR %x\n", regs[1]); /* Display %ecx */
+ err = -EPERM;
+ break;
+ }
err = wrmsr_safe_regs_on_cpu(cpu, regs);
if (err)
break;
--
2.21.0.352.gf09ad66450-goog
next prev parent reply other threads:[~2019-02-28 23:12 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-28 21:28 [PULL REQUEST] Lock down patches Matthew Garrett
2019-02-28 22:20 ` Mimi Zohar
2019-02-28 23:13 ` Matthew Garrett
2019-03-01 0:05 ` Mimi Zohar
2019-03-01 1:01 ` Matthew Garrett
2019-03-01 1:44 ` Mimi Zohar
2019-03-01 3:33 ` Matthew Garrett
2019-03-01 4:16 ` Mimi Zohar
2019-02-28 22:44 ` [PATCH 01/27] Add the ability to lock down access to the running kernel image Matthew Garrett
2019-02-28 22:44 ` [PATCH 02/27] Add a SysRq option to lift kernel lockdown Matthew Garrett
2019-02-28 23:10 ` [PATCH 01/27] Add the ability to lock down access to the running kernel image Matthew Garrett
2019-02-28 23:10 ` [PATCH 02/27] Add a SysRq option to lift kernel lockdown Matthew Garrett
2019-02-28 23:11 ` [PATCH 01/27] Add the ability to lock down access to the running kernel image Matthew Garrett
2019-02-28 23:11 ` [PATCH 02/27] Add a SysRq option to lift kernel lockdown Matthew Garrett
2019-02-28 23:11 ` [PATCH 01/27] Add the ability to lock down access to the running kernel image Matthew Garrett
2019-02-28 23:11 ` [PATCH 02/27] Add a SysRq option to lift kernel lockdown Matthew Garrett
2019-02-28 23:11 ` [PATCH 03/27] Enforce module signatures if the kernel is locked down Matthew Garrett
2019-02-28 23:11 ` [PATCH 04/27] Restrict /dev/{mem,kmem,port} when " Matthew Garrett
2019-02-28 23:11 ` [PATCH 05/27] kexec_load: Disable at runtime if " Matthew Garrett
2019-02-28 23:11 ` [PATCH 06/27] Copy secure_boot flag in boot params across kexec reboot Matthew Garrett
2019-02-28 23:11 ` [PATCH 07/27] kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE Matthew Garrett
2019-02-28 23:11 ` [PATCH 08/27] kexec_file: Restrict at runtime if the kernel is locked down Matthew Garrett
2019-03-01 2:05 ` Mimi Zohar
2019-02-28 23:11 ` [PATCH 09/27] hibernate: Disable when " Matthew Garrett
2019-03-19 22:15 ` Pavel Machek
2019-02-28 23:11 ` [PATCH 10/27] uswsusp: " Matthew Garrett
2019-02-28 23:11 ` [PATCH 11/27] PCI: Lock down BAR access " Matthew Garrett
2019-02-28 23:11 ` [PATCH 12/27] x86: Lock down IO port " Matthew Garrett
2019-02-28 23:11 ` Matthew Garrett [this message]
2019-02-28 23:11 ` [PATCH 14/27] ACPI: Limit access to custom_method " Matthew Garrett
2019-02-28 23:11 ` [PATCH 15/27] acpi: Ignore acpi_rsdp kernel param when the kernel has been " Matthew Garrett
2019-02-28 23:11 ` [PATCH 16/27] acpi: Disable ACPI table override if the kernel is " Matthew Garrett
2019-02-28 23:11 ` [PATCH 17/27] acpi: Disable APEI error injection " Matthew Garrett
2019-02-28 23:11 ` [PATCH 18/27] Prohibit PCMCIA CIS storage when " Matthew Garrett
2019-02-28 23:11 ` [PATCH 19/27] Lock down TIOCSSERIAL Matthew Garrett
2019-02-28 23:11 ` [PATCH 20/27] Lock down module params that specify hardware parameters (eg. ioport) Matthew Garrett
2019-02-28 23:11 ` [PATCH 21/27] x86/mmiotrace: Lock down the testmmiotrace module Matthew Garrett
2019-02-28 23:11 ` [PATCH 22/27] Lock down /proc/kcore Matthew Garrett
2019-02-28 23:11 ` [PATCH 23/27] Lock down kprobes Matthew Garrett
2019-02-28 23:12 ` [PATCH 24/27] bpf: Restrict kernel image access functions when the kernel is locked down Matthew Garrett
2019-02-28 23:12 ` [PATCH 25/27] Lock down perf Matthew Garrett
2019-02-28 23:12 ` [PATCH 26/27] debugfs: Restrict debugfs when the kernel is locked down Matthew Garrett
2019-02-28 23:12 ` [PATCH 27/27] lockdown: Print current->comm in restriction messages Matthew Garrett
2019-02-28 23:24 ` [PULL REQUEST] Lock down patches Randy Dunlap
2019-03-04 22:10 ` Matthew Garrett
2019-03-06 23:58 [PULL REQUEST] Kernel lockdown patches for 5.2 Matthew Garrett
2019-03-06 23:58 ` [PATCH 13/27] x86/msr: Restrict MSR access when the kernel is locked down Matthew Garrett
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