Blame x86-Restrict-MSR-access-when-module-loading-is-restr.patch
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From 85539b332c79fbce1b9f371ff1a2a8d489e65110 Mon Sep 17 00:00:00 2001
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From: Matthew Garrett <matthew.garrett@nebula.com>
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Date: Fri, 8 Feb 2013 11:12:13 -0800
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Subject: [PATCH 09/20] x86: Restrict MSR access when module loading is
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restricted
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Writing to MSRs should not be allowed if module loading is restricted,
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since it could lead to execution of arbitrary code in kernel mode. Based
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on a patch by Kees Cook.
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Cc: Kees Cook <keescook@chromium.org>
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Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>
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---
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arch/x86/kernel/msr.c | 7 +++++++
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1 file changed, 7 insertions(+)
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diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c
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index 7f3550acde1b..963ba4011923 100644
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--- a/arch/x86/kernel/msr.c
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+++ b/arch/x86/kernel/msr.c
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@@ -83,6 +83,9 @@ static ssize_t msr_write(struct file *file, const char __user *buf,
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int err = 0;
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ssize_t bytes = 0;
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+ if (secure_modules())
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+ return -EPERM;
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+
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if (count % 8)
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return -EINVAL; /* Invalid chunk size */
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@@ -130,6 +133,10 @@ static long msr_ioctl(struct file *file, unsigned int ioc, unsigned long arg)
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err = -EBADF;
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break;
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}
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+ if (secure_modules()) {
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+ err = -EPERM;
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+ break;
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+ }
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if (copy_from_user(®s, uregs, sizeof regs)) {
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err = -EFAULT;
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break;
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--
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2.9.3
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