From: "H. Peter Anvin" <hpa@zytor.com>
To: Kees Cook <keescook@chromium.org>, linux-kernel@vger.kernel.org
Cc: Matthew Garrett <matthew.garrett@nebula.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: Re: [PATCH] x86: Lock down MSR writing in secure boot
Date: Fri, 08 Feb 2013 11:17:24 -0800 [thread overview]
Message-ID: <00780235-deac-4f80-b936-867834e05661@email.android.com> (raw)
In-Reply-To: <20130208191213.GA25081@www.outflux.net>
We already have CAP_RAWIO for this in mainline; I am not sure if this should be harder than that...
Kees Cook <keescook@chromium.org> wrote:
>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(®s, uregs, sizeof regs)) {
> err = -EFAULT;
> break;
--
Sent from my mobile phone. Please excuse brevity and lack of formatting.
next prev parent reply other threads:[~2013-02-08 19:18 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-08 19:12 [PATCH] x86: Lock down MSR writing in secure boot Kees Cook
2013-02-08 19:17 ` H. Peter Anvin [this message]
2013-02-08 19:18 ` Kees Cook
2013-02-08 19:42 ` H. Peter Anvin
2013-02-08 20:14 ` Kees Cook
2013-02-08 20:18 ` H. Peter Anvin
2013-02-08 20:28 ` Kees Cook
2013-02-08 20:34 ` Matthew Garrett
2013-02-08 21:02 ` Kees Cook
2013-02-08 21:07 ` Matthew Garrett
2013-02-08 21:14 ` Josh Boyer
2013-02-08 23:09 ` Andy Lutomirski
2013-02-08 22:30 ` H. Peter Anvin
2013-02-08 23:06 ` Borislav Petkov
2013-02-08 23:26 ` Matthew Garrett
2013-02-09 1:22 ` H. Peter Anvin
2013-02-09 1:29 ` Matthew Garrett
2013-02-09 6:45 ` Kees Cook
2013-02-09 9:29 ` Borislav Petkov
2013-02-09 15:10 ` Kees Cook
2013-02-09 15:11 ` Matthew Garrett
2013-02-13 0:48 ` H. Peter Anvin
2013-02-13 5:39 ` Matthew Garrett
2013-02-13 6:12 ` H. Peter Anvin
2013-02-13 6:27 ` Matthew Garrett
2013-02-13 6:33 ` H. Peter Anvin
2013-02-13 6:41 ` Matthew Garrett
2013-02-13 17:20 ` H. Peter Anvin
2013-02-13 17:26 ` Matthew Garrett
2013-02-13 17:51 ` Casey Schaufler
2013-02-13 17:56 ` Matthew Garrett
2013-02-13 18:44 ` H. Peter Anvin
2013-02-13 18:51 ` Matthew Garrett
2013-02-13 22:26 ` H. Peter Anvin
2013-02-13 22:58 ` Casey Schaufler
2013-02-14 0:25 ` H. Peter Anvin
2013-02-14 0:44 ` Casey Schaufler
2013-02-14 1:04 ` Matthew Garrett
2013-02-14 1:08 ` H. Peter Anvin
2013-02-14 2:46 ` Matthew Garrett
2013-02-14 1:34 ` Casey Schaufler
2013-02-13 8:27 ` Paolo Bonzini
2013-02-13 17:21 ` H. Peter Anvin
2013-02-13 17:22 ` H. Peter Anvin
2013-02-13 19:55 ` Paolo Bonzini
2013-02-13 22:24 ` H. Peter Anvin
2013-02-08 19:17 ` Matthew Garrett
2013-02-08 19:21 ` Kees Cook
2013-02-08 19:27 ` Matthew Garrett
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