Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934150Ab3IDAo3 (ORCPT ); Tue, 3 Sep 2013 20:44:29 -0400 Received: from tundra.namei.org ([65.99.196.166]:50938 "EHLO tundra.namei.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934125Ab3IDAo0 (ORCPT ); Tue, 3 Sep 2013 20:44:26 -0400 Date: Wed, 4 Sep 2013 10:45:57 +1000 (EST) From: James Morris To: Matthew Garrett cc: linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org, keescook@chromium.org, hpa@zytor.com Subject: Re: [PATCH V3 03/11] x86: Lock down IO port access when module security is enabled In-Reply-To: <1378252218-18798-4-git-send-email-matthew.garrett@nebula.com> Message-ID: References: <1378252218-18798-1-git-send-email-matthew.garrett@nebula.com> <1378252218-18798-4-git-send-email-matthew.garrett@nebula.com> User-Agent: Alpine 2.02 (LRH 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2736 Lines: 90 On Tue, 3 Sep 2013, Matthew Garrett wrote: > IO port access would permit users to gain access to PCI configuration > registers, which in turn (on a lot of hardware) give access to MMIO register > space. This would potentially permit root to trigger arbitrary DMA, so lock > it down by default. > > Signed-off-by: Matthew Garrett Reviewed-by: James Morris > --- > arch/x86/kernel/ioport.c | 5 +++-- > drivers/char/mem.c | 4 ++++ > 2 files changed, 7 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kernel/ioport.c b/arch/x86/kernel/ioport.c > index 4ddaf66..00b4403 100644 > --- a/arch/x86/kernel/ioport.c > +++ b/arch/x86/kernel/ioport.c > @@ -15,6 +15,7 @@ > #include > #include > #include > +#include > #include > > /* > @@ -28,7 +29,7 @@ asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on) > > if ((from + num <= from) || (from + num > IO_BITMAP_BITS)) > return -EINVAL; > - if (turn_on && !capable(CAP_SYS_RAWIO)) > + if (turn_on && (!capable(CAP_SYS_RAWIO) || secure_modules())) > return -EPERM; > > /* > @@ -103,7 +104,7 @@ SYSCALL_DEFINE1(iopl, unsigned int, level) > return -EINVAL; > /* Trying to gain more privileges? */ > if (level > old) { > - if (!capable(CAP_SYS_RAWIO)) > + if (!capable(CAP_SYS_RAWIO) || secure_modules()) > return -EPERM; > } > regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) | (level << 12); > diff --git a/drivers/char/mem.c b/drivers/char/mem.c > index f895a8c..1af8664 100644 > --- a/drivers/char/mem.c > +++ b/drivers/char/mem.c > @@ -28,6 +28,7 @@ > #include > #include > #include > +#include > > #include > > @@ -563,6 +564,9 @@ static ssize_t write_port(struct file *file, const char __user *buf, > unsigned long i = *ppos; > const char __user *tmp = buf; > > + if (secure_modules()) > + return -EPERM; > + > if (!access_ok(VERIFY_READ, buf, count)) > return -EFAULT; > while (count-- > 0 && i < 65536) { > -- > 1.8.3.1 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- James Morris -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/