From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Garrett Subject: [PATCH 09/10] x86: Restrict MSR access when module loading is restricted Date: Mon, 19 Aug 2013 12:10:18 -0400 Message-ID: <1376928619-3775-9-git-send-email-matthew.garrett@nebula.com> References: <1376928619-3775-1-git-send-email-matthew.garrett@nebula.com> Return-path: In-Reply-To: <1376928619-3775-1-git-send-email-matthew.garrett@nebula.com> Sender: linux-kernel-owner@vger.kernel.org To: linux-kernel@vger.kernel.org Cc: linux-efi@vger.kernel.org, jwboyer@redhat.com, keescook@chromium.org, Matthew Garrett List-Id: linux-efi@vger.kernel.org Writing to MSRs should not be allowed if module loading is restricted, since it could lead to execution of arbitrary code in kernel mode. Based on a patch by Kees Cook. Cc: Kees Cook Signed-off-by: Matthew Garrett --- 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 88458fa..d08f7e3 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 (secure_modules()) + 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 (secure_modules()) { + err = -EPERM; + break; + } if (copy_from_user(®s, uregs, sizeof regs)) { err = -EFAULT; break; -- 1.8.3.1