From patchwork Tue Mar 26 18:27:26 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Garrett X-Patchwork-Id: 10871939 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 2C27013B5 for ; Tue, 26 Mar 2019 18:28:24 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1950E28DD7 for ; Tue, 26 Mar 2019 18:28:24 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 0E33728E33; Tue, 26 Mar 2019 18:28:24 +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 8352128DD7 for ; Tue, 26 Mar 2019 18:28:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732682AbfCZS2W (ORCPT ); Tue, 26 Mar 2019 14:28:22 -0400 Received: from mail-ua1-f73.google.com ([209.85.222.73]:33791 "EHLO mail-ua1-f73.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732681AbfCZS2V (ORCPT ); Tue, 26 Mar 2019 14:28:21 -0400 Received: by mail-ua1-f73.google.com with SMTP id h6so1622915uab.0 for ; Tue, 26 Mar 2019 11:28:21 -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=m5EpQp8h0Y4rOl6Y1bbFAZQnIUUjTzjUqWwPJEltX0Y=; b=Yz7oOrcDdKUM0oYpsGth5oCv8+Sc+iqvbZ8HKnhPKCnBF9rUHCL9szQCMAPU1PE8KZ V5oNz+OBCLawb6XGwCVNO/3W7ZIGW6CJqa38iNh+smM0l3Mf3WI096uUxVztD+vMlcy8 withllnQOAKuH6gF0+c6jcTe8VCipjbIFvdZQ3SG7qlyXzoR+Tduukj9v5gmr817WjTN 9qDDUFYKJxhZTZ6Uwfhk7qeYMwY0kNDGpr/Xub4PUqKY1bIS3otzcyj76HMmWPO1Cupi V7GyBI5YYjxdJUAmUSXaa8vzKtz1GNVChjlfHcl09ljj04vfopWnPSjdHPO8UC5ktyD4 6Vaw== 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=m5EpQp8h0Y4rOl6Y1bbFAZQnIUUjTzjUqWwPJEltX0Y=; b=ET1cmGu5LmL2GQdYA0trgNBgSaYQdGqFkLxCg/zxENkBI6Qy7Lvsv7L3tFE7lrGjP0 2WlZCHsIdboDxEiiuer6gqH7KvTiROIzJKnWSyHBLnHa9Lt1IsWIqsxSH9c4YIx86+Ad hXpN8qMs1qvog35B/8GEBaduXK8V1MqG59c3EnIIjpy3N/AOo4Kih7+c86RdfGdKExRp ZAiIRMnFVze/VvlgcwLKI0TMF73UKUIMgqpYc680fi4nDLRk6Td/qVF9CnAisoOFXlYs hLr4rJmf9imErYEnqtCHkBjFZFdZQnbaNJlkFtZEtA71bHLGSe9TFFRT/wlxF2+CsoLd 30pw== X-Gm-Message-State: APjAAAVNKkWqjddcak0TJxgkwvRaW4369AoD4zxHe6cE0vh9tr5LTlWY lif2pp9era8ChYnLoz9KoCFXGycMp2BakTYZKY64Lw== X-Google-Smtp-Source: APXvYqxJT/ULfLCwvV7wSB2GAtE6Vz8ph2N7xnq6Ot24PIma7JsvCCcrM8TBMNJZ/wPOc6HUu0fWwieS5ffY5o8z3DZmWA== X-Received: by 2002:a1f:a4d:: with SMTP id 74mr14878315vkk.13.1553624900606; Tue, 26 Mar 2019 11:28:20 -0700 (PDT) Date: Tue, 26 Mar 2019 11:27:26 -0700 In-Reply-To: <20190326182742.16950-1-matthewgarrett@google.com> Message-Id: <20190326182742.16950-11-matthewgarrett@google.com> Mime-Version: 1.0 References: <20190326182742.16950-1-matthewgarrett@google.com> X-Mailer: git-send-email 2.21.0.392.gf8f6787159e-goog Subject: [PATCH V31 10/25] 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, linux-api@vger.kernel.org, luto@kernel.org, Matthew Garrett , Matthew Garrett , Bjorn Helgaas , linux-pci@vger.kernel.org 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: David Howells Signed-off-by: Matthew Garrett Acked-by: Bjorn Helgaas 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..59d02088945e 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", LOCKDOWN_INTEGRITY)) + 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", LOCKDOWN_INTEGRITY)) + 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", LOCKDOWN_INTEGRITY)) + 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..85769f222b6d 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", LOCKDOWN_INTEGRITY)) + 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", LOCKDOWN_INTEGRITY)) + 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", LOCKDOWN_INTEGRITY)) return -EPERM; if (fpriv->mmap_state == pci_mmap_io) { diff --git a/drivers/pci/syscall.c b/drivers/pci/syscall.c index d96626c614f5..0669cb09e792 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", LOCKDOWN_INTEGRITY)) return -EPERM; dev = pci_get_domain_bus_and_slot(0, bus, dfn);