From patchwork Thu Feb 28 23:11:47 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Garrett X-Patchwork-Id: 10834237 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 1ABB5139A for ; Thu, 28 Feb 2019 23:12:36 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 094932FC41 for ; Thu, 28 Feb 2019 23:12:36 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id EE20F2FC3B; Thu, 28 Feb 2019 23:12:35 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-14.5 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,RCVD_IN_DNSWL_HI,USER_IN_DEF_DKIM_WL autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id CDE522FC3B for ; Thu, 28 Feb 2019 23:12:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387619AbfB1XMd (ORCPT ); Thu, 28 Feb 2019 18:12:33 -0500 Received: from mail-pf1-f202.google.com ([209.85.210.202]:38015 "EHLO mail-pf1-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387766AbfB1XMd (ORCPT ); Thu, 28 Feb 2019 18:12:33 -0500 Received: by mail-pf1-f202.google.com with SMTP id d5so1297141pfo.5 for ; Thu, 28 Feb 2019 15:12:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=1iAkG3SYFFYNE2aS5Uy/nPaL9mRV8qNg8EUrtDxONjY=; b=uuxcthmJNDGwdJv5YpH6uELSKb27+zpDpVvWg4XUCi1qsYzIbaO/WzbJbI+FgFxYhX dE7U/DyEntkC0oMXihkOtsUYnqczFs5zCG7GTKBTHGNGyWTpKm1VUAqOofwik/d813qQ 7VdLvbS/fIlHFvB4aqFgXFYFlNMbXyWCmI8WS6VxtPJ22aLyi84bOTFoHZGlcDDCjs/f oO0rWxy+g0QrufGhvSnM6CFXDpQZ03yp4cB07nQnZh5nhmK7jVs+7cm3oWaNZMLmX6oJ OxDq66oYZhm7uLm4/9uHd1kiLBAx9QV9Oi+Ug6tLh+5Mj8A07cFYfrMZtLK5d2xYxN5x ETpw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=1iAkG3SYFFYNE2aS5Uy/nPaL9mRV8qNg8EUrtDxONjY=; b=GB8L+WwiQBgFovDqEUdHFLyWqC+1VxkvluGNqDDKjv6C5vjCZTBn/ZuXx6Z9nl2Ye2 4CppVamn9xrff1BAp882gOMVqCKr0U8MZLnuI1UDQqR645jXkAkHaXTGJxQ9CQYRDA6z 0Yopi2nLuRBPtL0FmSNiqlb5bmab4fu+IztkFecWe2TqQ8Rkjsmb+vqCfTxOcklsNYxl IR98h5x/8KzvvG5ixuxh5awnrG8eQBjXR34RXidFGBVHA1J2g1f9XRXQ7AMwuVisJMuc PlTSdcFpj2uGG1p1KDrFXM54LC07MPpAVfMNCN/wg+tXdosbucSr682QkB/PxRdWRjVw CA6g== X-Gm-Message-State: APjAAAX8VCcwFAfMhvdo3Y1PFjQnsqTK7SzWA6ZBYCCmvbJp8wCrFckl lKuLnOycWeikXeBUNZ1eK+95oaJF7mKl9YaIFvT5DA== X-Google-Smtp-Source: APXvYqxAbpqSdYwQtV399CqmoPDFoqEoZZNTH4jRNtVv0TtSWcEXqkpl9CGuRySxRH0c2gqIp23VtCLK006xVbMvMGRfgg== X-Received: by 2002:a17:902:b682:: with SMTP id c2mr652302pls.107.1551395552587; Thu, 28 Feb 2019 15:12:32 -0800 (PST) Date: Thu, 28 Feb 2019 15:11:47 -0800 In-Reply-To: <20190228231203.212359-1-matthewgarrett@google.com> Message-Id: <20190228231203.212359-11-matthewgarrett@google.com> Mime-Version: 1.0 References: <20190228231203.212359-1-matthewgarrett@google.com> X-Mailer: git-send-email 2.21.0.352.gf09ad66450-goog Subject: [PATCH 11/27] PCI: Lock down BAR access when the kernel is locked down From: Matthew Garrett To: jmorris@namei.org Cc: linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, dhowells@redhat.com Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP 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 Acked-by: Bjorn Helgaas Reviewed-by: "Lee, Chun-Yi" cc: linux-pci@vger.kernel.org --- 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 9ecfe13157c0..40c14574fcf8 100644 --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -905,6 +905,9 @@ 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("Direct PCI access")) + return -EPERM; + if (off > dev->cfg_size) return 0; if (off + count > dev->cfg_size) { @@ -1167,6 +1170,9 @@ static int pci_mmap_resource(struct kobject *kobj, struct bin_attribute *attr, enum pci_mmap_state mmap_type; struct resource *res = &pdev->resource[bar]; + if (kernel_is_locked_down("Direct PCI access")) + return -EPERM; + if (res->flags & IORESOURCE_MEM && iomem_is_exclusive(res->start)) return -EINVAL; @@ -1242,6 +1248,9 @@ 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("Direct PCI access")) + 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 6fa1627ce08d..1549cdd0710e 100644 --- a/drivers/pci/proc.c +++ b/drivers/pci/proc.c @@ -117,6 +117,9 @@ 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("Direct PCI access")) + 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 (kernel_is_locked_down("Direct PCI access")) + return -EPERM; + switch (cmd) { case PCIIOC_CONTROLLER: ret = pci_domain_nr(dev->bus); @@ -237,7 +243,8 @@ 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 = 0, res_bit = IORESOURCE_MEM; - if (!capable(CAP_SYS_RAWIO)) + if (!capable(CAP_SYS_RAWIO) || + kernel_is_locked_down("Direct PCI access")) return -EPERM; if (fpriv->mmap_state == pci_mmap_io) { diff --git a/drivers/pci/syscall.c b/drivers/pci/syscall.c index d96626c614f5..b8a08d3166a1 100644 --- a/drivers/pci/syscall.c +++ b/drivers/pci/syscall.c @@ -90,7 +90,8 @@ 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("Direct PCI access")) return -EPERM; dev = pci_get_domain_bus_and_slot(0, bus, dfn);