From patchwork Mon Mar 25 22:09:37 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Garrett X-Patchwork-Id: 10870229 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 E65FB18A6 for ; Mon, 25 Mar 2019 22:12:19 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D78EA29053 for ; Mon, 25 Mar 2019 22:12:19 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id CBE9F2905C; Mon, 25 Mar 2019 22:12:19 +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 540E829067 for ; Mon, 25 Mar 2019 22:12:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730749AbfCYWMR (ORCPT ); Mon, 25 Mar 2019 18:12:17 -0400 Received: from mail-ua1-f74.google.com ([209.85.222.74]:50639 "EHLO mail-ua1-f74.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730882AbfCYWKY (ORCPT ); Mon, 25 Mar 2019 18:10:24 -0400 Received: by mail-ua1-f74.google.com with SMTP id i13so1333454ual.17 for ; Mon, 25 Mar 2019 15:10:24 -0700 (PDT) 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=5YTphNCZAMpEXxUv7rOxGetCpK0M7qq91rW7GzRAqO4=; b=W9BwWhhEk3R9kt9oYI4KanwoednXfPb3X+Yi6Dt+Nylfbq+ckM0NYWhPN6lcqRHtsy 9q7/RIgxD9eUug1W9CSmnVU3ZqOeo8hO7yARqNknkUxa12HmTFKKHfv3L9813irQS/l1 8GDnk8wMkQk4BFb3K2iIxXEbzphn1Uc9ullAkkMqIv2vP4KiH/ij5Ycgu0kkcfPsdowj Ca3PcotEOk1XWjCcZWRdKc6GRA9wVXrQlpkI9MUpz/sAYxBEJomW2EYBxc2smbvEkxtd CFHMc18928CoBKgH9zFhL5iznVkC7KOVPVm3dFRwVvZo/y8nCvHyQGefvJRQCUDmmDbY 0itg== 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=5YTphNCZAMpEXxUv7rOxGetCpK0M7qq91rW7GzRAqO4=; b=IzSpzoUEDXWasRWG37Pz0xI8Tcg61AizXR6Pd6Ai5+xlHtrfR2SOok2NzQx7vfz15O Kdhrb9tDzPyUYHELo43ULyWpSJ6R8eH3zGxeZQpxt+JrJjIHbxOKfdBokPix4g3Cm0TI SJPLlVANvFjaGbecZj8LJvkSnRy+h59bZgNFgRWbwAyJuHaP0l6nueUYjxi82HG/E5EF zHh4gUl/lDd+bSvqACqcR1qOPgE8MqEp6S0cJrLfmSdfkp4S2hRUpIItWxvdztdFx+rx pg1hohq+gKenrJJR9ElQdH9wAee/0SI7RNNgEkn2uVXjg+HTkNgEAObBnNQ27jp0Ggiw 7QIA== X-Gm-Message-State: APjAAAWOFyu+PmCDWQcQYsIgJcTy6FJix2NTs0/IX9oAuc2xZYKm04xj Hb8wfqALvaqKwC7hAwDpDJguFq5bNEvZodLkfVoC0g== X-Google-Smtp-Source: APXvYqyzu5YW23qFSwxQFEBET1+I50UyXTTqBzSetMilQACx2b/chaObguWIQJwc91+CoxdOnaCeEQxy/5kxawWHpIRqTA== X-Received: by 2002:a1f:b587:: with SMTP id e129mr15961378vkf.23.1553551823984; Mon, 25 Mar 2019 15:10:23 -0700 (PDT) Date: Mon, 25 Mar 2019 15:09:37 -0700 In-Reply-To: <20190325220954.29054-1-matthewgarrett@google.com> Message-Id: <20190325220954.29054-11-matthewgarrett@google.com> Mime-Version: 1.0 References: <20190325220954.29054-1-matthewgarrett@google.com> X-Mailer: git-send-email 2.21.0.392.gf8f6787159e-goog Subject: [PATCH 10/27] 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, Matthew Garrett , Bjorn Helgaas , linux-pci@vger.kernel.org, Matthew Garrett 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 cc: linux-pci@vger.kernel.org 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 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);