Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753876AbaBZULo (ORCPT ); Wed, 26 Feb 2014 15:11:44 -0500 Received: from cavan.codon.org.uk ([93.93.128.6]:44102 "EHLO cavan.codon.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753369AbaBZULi (ORCPT ); Wed, 26 Feb 2014 15:11:38 -0500 From: Matthew Garrett To: linux-kernel@vger.kernel.org Cc: keescook@chromium.org, gregkh@linuxfoundation.org, hpa@zytor.com, linux-efi@vger.kernel.org, jmorris@namei.org, linux-security-module@vger.kernel.org, Matthew Garrett Subject: [PATCH 03/12] PCI: Lock down BAR access when trusted_kernel is true Date: Wed, 26 Feb 2014 15:11:04 -0500 Message-Id: <1393445473-15068-4-git-send-email-matthew.garrett@nebula.com> X-Mailer: git-send-email 1.8.5.3 In-Reply-To: <1393445473-15068-1-git-send-email-matthew.garrett@nebula.com> References: <1393445473-15068-1-git-send-email-matthew.garrett@nebula.com> X-SA-Do-Not-Run: Yes X-SA-Exim-Connect-IP: 209.6.207.143 X-SA-Exim-Mail-From: matthew.garrett@nebula.com X-SA-Exim-Scanned: No (on cavan.codon.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. This should be prevented if trusted_kernel has been set. Default to paranoid - in future we can potentially relax this for sufficiently IOMMU-isolated devices. Signed-off-by: Matthew Garrett --- drivers/pci/pci-sysfs.c | 9 +++++++++ drivers/pci/proc.c | 9 ++++++++- 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 276ef9c..256f373 100644 --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -663,6 +663,9 @@ pci_write_config(struct file* filp, struct kobject *kobj, loff_t init_off = off; u8 *data = (u8*) buf; + if (get_trusted_kernel()) + return -EPERM; + if (off > dev->cfg_size) return 0; if (off + count > dev->cfg_size) { @@ -969,6 +972,9 @@ pci_mmap_resource(struct kobject *kobj, struct bin_attribute *attr, resource_size_t start, end; int i; + if (get_trusted_kernel()) + return -EPERM; + for (i = 0; i < PCI_ROM_RESOURCE; i++) if (res == &pdev->resource[i]) break; @@ -1076,6 +1082,9 @@ pci_write_resource_io(struct file *filp, struct kobject *kobj, struct bin_attribute *attr, char *buf, loff_t off, size_t count) { + if (get_trusted_kernel()) + 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 46d1378..990b24b 100644 --- a/drivers/pci/proc.c +++ b/drivers/pci/proc.c @@ -11,6 +11,7 @@ #include #include #include +#include #include #include #include "pci.h" @@ -117,6 +118,9 @@ proc_bus_pci_write(struct file *file, const char __user *buf, size_t nbytes, lof int size = dev->cfg_size; int cnt; + if (get_trusted_kernel()) + return -EPERM; + if (pos >= size) return 0; if (nbytes >= size) @@ -196,6 +200,9 @@ static long proc_bus_pci_ioctl(struct file *file, unsigned int cmd, #endif /* HAVE_PCI_MMAP */ int ret = 0; + if (get_trusted_kernel()) + return -EPERM; + switch (cmd) { case PCIIOC_CONTROLLER: ret = pci_domain_nr(dev->bus); @@ -234,7 +241,7 @@ 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) || (get_trusted_kernel())) 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 24750a1..d962710 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) || (get_trusted_kernel())) return -EPERM; dev = pci_get_bus_and_slot(bus, dfn); -- 1.8.5.3 -- 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/