Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934044AbdDEUQ7 (ORCPT ); Wed, 5 Apr 2017 16:16:59 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59034 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933966AbdDEUQg (ORCPT ); Wed, 5 Apr 2017 16:16:36 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com CFA5CC04BD37 Authentication-Results: ext-mx07.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx07.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=dhowells@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com CFA5CC04BD37 Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH 12/24] PCI: Lock down BAR access when the kernel is locked down From: David Howells To: linux-kernel@vger.kernel.org Cc: matthew.garrett@nebula.com, linux-efi@vger.kernel.org, gnomes@lxorguk.ukuu.org.uk, linux-pci@vger.kernel.org, dhowells@redhat.com, linux-security-module@vger.kernel.org, keyrings@vger.kernel.org, gregkh@linuxfoundation.org Date: Wed, 05 Apr 2017 21:16:18 +0100 Message-ID: <149142337836.5101.13971561682218232219.stgit@warthog.procyon.org.uk> In-Reply-To: <149142326734.5101.4596394505987813763.stgit@warthog.procyon.org.uk> References: <149142326734.5101.4596394505987813763.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Wed, 05 Apr 2017 20:16:21 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3148 Lines: 98 From: Matthew Garrett Any hardware that can potentially generate DMA has to be locked down in order to avoid it being possible for an attacker to modify kernel code, allowing them to circumvent disabled module loading or module signing. Default to paranoid - in future we can potentially relax this for sufficiently IOMMU-isolated devices. Signed-off-by: Matthew Garrett Signed-off-by: David Howells cc: linux-pci@vger.kernel.org --- drivers/pci/pci-sysfs.c | 9 +++++++++ drivers/pci/proc.c | 8 +++++++- drivers/pci/syscall.c | 2 +- 3 files changed, 17 insertions(+), 2 deletions(-) diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c index 25d010d449a3..f70b3668036f 100644 --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -727,6 +727,9 @@ static ssize_t pci_write_config(struct file *filp, struct kobject *kobj, loff_t init_off = off; u8 *data = (u8 *) buf; + if (kernel_is_locked_down()) + return -EPERM; + if (off > dev->cfg_size) return 0; if (off + count > dev->cfg_size) { @@ -1018,6 +1021,9 @@ static int pci_mmap_resource(struct kobject *kobj, struct bin_attribute *attr, resource_size_t start, end; int i; + if (kernel_is_locked_down()) + return -EPERM; + for (i = 0; i < PCI_ROM_RESOURCE; i++) if (res == &pdev->resource[i]) break; @@ -1117,6 +1123,9 @@ static ssize_t pci_write_resource_io(struct file *filp, struct kobject *kobj, struct bin_attribute *attr, char *buf, loff_t off, size_t count) { + if (kernel_is_locked_down()) + return -EPERM; + return pci_resource_io(filp, kobj, attr, buf, off, count, true); } diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c index f82710a8694d..139d6f09ae7b 100644 --- a/drivers/pci/proc.c +++ b/drivers/pci/proc.c @@ -116,6 +116,9 @@ static ssize_t proc_bus_pci_write(struct file *file, const char __user *buf, int size = dev->cfg_size; int cnt; + if (kernel_is_locked_down()) + return -EPERM; + if (pos >= size) return 0; if (nbytes >= size) @@ -195,6 +198,9 @@ static long proc_bus_pci_ioctl(struct file *file, unsigned int cmd, #endif /* HAVE_PCI_MMAP */ int ret = 0; + if (kernel_is_locked_down()) + return -EPERM; + switch (cmd) { case PCIIOC_CONTROLLER: ret = pci_domain_nr(dev->bus); @@ -233,7 +239,7 @@ static int proc_bus_pci_mmap(struct file *file, struct vm_area_struct *vma) struct pci_filp_private *fpriv = file->private_data; int i, ret, write_combine; - if (!capable(CAP_SYS_RAWIO)) + if (!capable(CAP_SYS_RAWIO) || kernel_is_locked_down()) return -EPERM; /* Make sure the caller is mapping a real resource for this device */ diff --git a/drivers/pci/syscall.c b/drivers/pci/syscall.c index 9bf993e1f71e..c09524738ceb 100644 --- a/drivers/pci/syscall.c +++ b/drivers/pci/syscall.c @@ -92,7 +92,7 @@ SYSCALL_DEFINE5(pciconfig_write, unsigned long, bus, unsigned long, dfn, u32 dword; int err = 0; - if (!capable(CAP_SYS_ADMIN)) + if (!capable(CAP_SYS_ADMIN) || kernel_is_locked_down()) return -EPERM; dev = pci_get_bus_and_slot(bus, dfn);