Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934123Ab3IDAoU (ORCPT ); Tue, 3 Sep 2013 20:44:20 -0400 Received: from tundra.namei.org ([65.99.196.166]:50933 "EHLO tundra.namei.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761445Ab3IDAoT (ORCPT ); Tue, 3 Sep 2013 20:44:19 -0400 Date: Wed, 4 Sep 2013 10:45:37 +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 02/11] PCI: Lock down BAR access when module security is enabled In-Reply-To: <1378252218-18798-3-git-send-email-matthew.garrett@nebula.com> Message-ID: References: <1378252218-18798-1-git-send-email-matthew.garrett@nebula.com> <1378252218-18798-3-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: 4121 Lines: 135 On Tue, 3 Sep 2013, Matthew Garrett wrote: > Any hardware that can potentially generate DMA has to be locked down from > userspace 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 Reviewed-by: James Morris > --- > drivers/pci/pci-sysfs.c | 10 ++++++++++ > drivers/pci/proc.c | 8 +++++++- > drivers/pci/syscall.c | 3 ++- > 3 files changed, 19 insertions(+), 2 deletions(-) > > diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c > index c0dbe1f..cd4e35f 100644 > --- a/drivers/pci/pci-sysfs.c > +++ b/drivers/pci/pci-sysfs.c > @@ -29,6 +29,7 @@ > #include > #include > #include > +#include > #include "pci.h" > > static int sysfs_initialized; /* = 0 */ > @@ -624,6 +625,9 @@ pci_write_config(struct file* filp, struct kobject *kobj, > loff_t init_off = off; > u8 *data = (u8*) buf; > > + if (secure_modules()) > + return -EPERM; > + > if (off > dev->cfg_size) > return 0; > if (off + count > dev->cfg_size) { > @@ -930,6 +934,9 @@ pci_mmap_resource(struct kobject *kobj, struct bin_attribute *attr, > resource_size_t start, end; > int i; > > + if (secure_modules()) > + return -EPERM; > + > for (i = 0; i < PCI_ROM_RESOURCE; i++) > if (res == &pdev->resource[i]) > break; > @@ -1037,6 +1044,9 @@ pci_write_resource_io(struct file *filp, struct kobject *kobj, > struct bin_attribute *attr, char *buf, > loff_t off, size_t count) > { > + if (secure_modules()) > + 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 cdc7836..e3d498b 100644 > --- a/drivers/pci/proc.c > +++ b/drivers/pci/proc.c > @@ -117,6 +117,9 @@ proc_bus_pci_write(struct file *file, const char __user *buf, size_t nbytes, lof > int size = dev->cfg_size; > int cnt; > > + if (secure_modules()) > + return -EPERM; > + > if (pos >= size) > return 0; > if (nbytes >= size) > @@ -196,6 +199,9 @@ static long proc_bus_pci_ioctl(struct file *file, unsigned int cmd, > #endif /* HAVE_PCI_MMAP */ > int ret = 0; > > + if (secure_modules()) > + return -EPERM; > + > switch (cmd) { > case PCIIOC_CONTROLLER: > ret = pci_domain_nr(dev->bus); > @@ -234,7 +240,7 @@ 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; > > - if (!capable(CAP_SYS_RAWIO)) > + if (!capable(CAP_SYS_RAWIO) || secure_modules()) > 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 e1c1ec5..bffbf71 100644 > --- a/drivers/pci/syscall.c > +++ b/drivers/pci/syscall.c > @@ -10,6 +10,7 @@ > #include > #include > #include > +#include > #include > #include "pci.h" > > @@ -92,7 +93,7 @@ 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) || secure_modules()) > return -EPERM; > > dev = pci_get_bus_and_slot(bus, dfn); > -- > 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/