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

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This commit is contained in:
Josh Boyer 2013-02-11 10:23:48 -05:00
parent e6a8495624
commit 79353e61f2
2 changed files with 93 additions and 1 deletions
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3
kernel.spec
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@ -62,7 +62,7 @@ Summary: The Linux kernel
# For non-released -rc kernels, this will be appended after the rcX and
# gitX tags, so a 3 here would become part of release "0.rcX.gitX.3"
#
%global baserelease 1
%global baserelease 2
%global fedora_build %{baserelease}
# base_sublevel is the kernel version we're starting with and patching
@ -2314,6 +2314,7 @@ fi
# || ||
%changelog
* Mon Feb 11 2013 Josh Boyer <jwboyer@redhat.com>
- Add patch from Kees Cook to restrict MSR writting in secure boot mode
- Build PATA_MACIO in on powerpc (rhbz 831361)
* Fri Feb 08 2013 Josh Boyer <jwboyer@redhat.com> - 3.8.0-0.rc7.git0.1

91
secure-boot-20130206.patch
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@ -1387,3 +1387,94 @@ index 96bd86b..6e1331c 100644
--
1.8.1
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Fri, 8 Feb 2013 11:12:14 -0800
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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