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Add patch from Kees Cook to restrict MSR writting in secure boot mode

This commit is contained in:
Josh Boyer 2013-02-11 10:20:06 -05:00
parent 31d643927c
commit 4c338c68e6
2 changed files with 92 additions and 0 deletions
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1
kernel.spec
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@ -2379,6 +2379,7 @@ fi
# || ||
%changelog
* Mon Feb 11 2013 Josh Boyer <jwboyer@redhat.com>
- Add patch from Kees Cook to restrict MSR writting in secure boot mode
- Add patch to honor MokSBState (rhbz 907406)
* Thu Feb 7 2013 Peter Robinson <pbrobinson@fedoraproject.org>

91
secure-boot-3.7-20130204.patch
View File

@ -1390,3 +1390,94 @@ index 96bd86b..6e1331c 100644
--
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Date: Fri, 8 Feb 2013 11:12:13 -0800
From: Kees Cook <keescook@chromium.org>
To: linux-kernel@vger.kernel.org
Cc: Matthew Garrett <matthew.garrett@nebula.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, x86@kernel.org,
linux-efi@vger.kernel.org, linux-security-module@vger.kernel.org
Subject: [PATCH] x86: Lock down MSR writing in secure boot
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Writing to MSRs should not be allowed unless CAP_COMPROMISE_KERNEL is
set since it could lead to execution of arbitrary code in kernel mode.
Signed-off-by: Kees Cook <keescook@chromium.org>
---
This would be used on top of Matthew Garrett's existing "Secure boot
policy support" patch series.
---
arch/x86/kernel/msr.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c
index 4929502..adaab3d 100644
--- a/arch/x86/kernel/msr.c
+++ b/arch/x86/kernel/msr.c
@@ -103,6 +103,9 @@ static ssize_t msr_write(struct file *file, const char __user *buf,
int err = 0;
ssize_t bytes = 0;
+ if (!capable(CAP_COMPROMISE_KERNEL))
+ return -EPERM;
+
if (count % 8)
return -EINVAL; /* Invalid chunk size */
@@ -150,6 +153,10 @@ static long msr_ioctl(struct file *file, unsigned int ioc, unsigned long arg)
err = -EBADF;
break;
}
+ if (!capable(CAP_COMPROMISE_KERNEL)) {
+ err = -EPERM;
+ break;
+ }
if (copy_from_user(&regs, uregs, sizeof regs)) {
err = -EFAULT;
break;
--
1.7.9.5
--
Kees Cook
Chrome OS Security
--
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