From patchwork Thu Aug 8 00:07:03 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Garrett X-Patchwork-Id: 11082967 X-Patchwork-Delegate: bhelgaas@google.com 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 B8714912 for ; Thu, 8 Aug 2019 00:09:30 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A6C2A28AAE for ; Thu, 8 Aug 2019 00:09:30 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9AF1228AC8; Thu, 8 Aug 2019 00:09:30 +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=-15.5 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,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 132B328AAE for ; Thu, 8 Aug 2019 00:09:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389573AbfHHAHy (ORCPT ); Wed, 7 Aug 2019 20:07:54 -0400 Received: from mail-qt1-f202.google.com ([209.85.160.202]:38646 "EHLO mail-qt1-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389540AbfHHAHy (ORCPT ); Wed, 7 Aug 2019 20:07:54 -0400 Received: by mail-qt1-f202.google.com with SMTP id r58so83950337qtb.5 for ; Wed, 07 Aug 2019 17:07:53 -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=IqUClIssxa6D6MoIAE+ms+qpgX9OHdd3voCN/TpeHYo=; b=dvTWxtC+XmP29mXEKHzgd7oc0DtaDCI/IQTve+uHnDOnc/fS9aFi3DQJB1XBKaXVTS MrvbR7qvSyNd8roEdY1MLASnQlX6sRrF7psmphC50/Ens662JAYc16vT9K3leIbE15B+ 9B2McclD+lw5gjBrvhpYqChlRcXKSIvP6sLrT1YJ6ZQN00l66PmFEwe/Rd8ADIK3kKKO ugyG0f2b4LLwbxxKCgYxKILazJSTsbiZG5WmhylSPt6Qw0rpng5P9x2pCGIJ1IT1V7kx 4O6YpXP5jBtlYY12lFTxqPWLnP5qqBpzIu2RuCvWPhMv4iu7GaOpdY2PgqyUZ/9TU1l8 HSWA== 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=IqUClIssxa6D6MoIAE+ms+qpgX9OHdd3voCN/TpeHYo=; b=CIaM13VEnqhLt31m74VD76YBZa/857PPJ+qQ9Jp4+L/FjzHCaPRGANT0FIer1LY5ri 5l71Uxwh+n8fTcX/ndf8lNhfEaMjfW9TDkza47RBne2bwWoU89Iuqlj8psiYzVm5/q3S gtiYY3Qzd8PgEi7O7fKkRrdE8DdnQWpw7bVpUMrVX+Jjnaxt83lB9k+VYGVK5yAdom4I D+DbHoOb8UOO94QuAgXmmdwb7pIavFB8Q3rmyLHFKlzSt6IWFT7gF0a3hfJlcVf92nPh b+8w62BcM/VL4fJHcYFhJ5E35+yVpUdEUSWm4PXgFRv94dH3oZTuilYmdIzN04pFrFnS B2uw== X-Gm-Message-State: APjAAAVHBApafeeYuhrgBV3ovhjuhCVBCFr/XWYuRJNbNvKQ97rKK0r5 q6g4BCLu2oMDAzz9QDzwlpV+yxXsAJp/4ODHeGEa5g== X-Google-Smtp-Source: APXvYqx7OxYh/pP2s/xRJ1zCkpoOH7xQOniVOy105OLiF/Pwgi60FgUmTi0Sl3Huy1MZiiKW/EwR6sS5AWC9ALU/DqE+kg== X-Received: by 2002:ac8:7251:: with SMTP id l17mr10749986qtp.277.1565222872565; Wed, 07 Aug 2019 17:07:52 -0700 (PDT) Date: Wed, 7 Aug 2019 17:07:03 -0700 In-Reply-To: <20190808000721.124691-1-matthewgarrett@google.com> Message-Id: <20190808000721.124691-12-matthewgarrett@google.com> Mime-Version: 1.0 References: <20190808000721.124691-1-matthewgarrett@google.com> X-Mailer: git-send-email 2.22.0.770.g0f2c4a37fd-goog Subject: [PATCH V38 11/29] 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, linux-api@vger.kernel.org, Matthew Garrett , David Howells , Matthew Garrett , Bjorn Helgaas , Kees Cook , linux-pci@vger.kernel.org Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org 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 Reviewed-by: Kees Cook cc: linux-pci@vger.kernel.org --- drivers/pci/pci-sysfs.c | 16 ++++++++++++++++ drivers/pci/proc.c | 14 ++++++++++++-- drivers/pci/syscall.c | 4 +++- include/linux/security.h | 1 + security/lockdown/lockdown.c | 1 + 5 files changed, 33 insertions(+), 3 deletions(-) diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c index 965c72104150..396c1a90c0e1 100644 --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -906,6 +906,11 @@ static ssize_t pci_write_config(struct file *filp, struct kobject *kobj, unsigned int size = count; loff_t init_off = off; u8 *data = (u8 *) buf; + int ret; + + ret = security_locked_down(LOCKDOWN_PCI_ACCESS); + if (ret) + return ret; if (off > dev->cfg_size) return 0; @@ -1167,6 +1172,11 @@ static int pci_mmap_resource(struct kobject *kobj, struct bin_attribute *attr, int bar = (unsigned long)attr->private; enum pci_mmap_state mmap_type; struct resource *res = &pdev->resource[bar]; + int ret; + + ret = security_locked_down(LOCKDOWN_PCI_ACCESS); + if (ret) + return ret; if (res->flags & IORESOURCE_MEM && iomem_is_exclusive(res->start)) return -EINVAL; @@ -1243,6 +1253,12 @@ 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) { + int ret; + + ret = security_locked_down(LOCKDOWN_PCI_ACCESS); + if (ret) + return ret; + return pci_resource_io(filp, kobj, attr, buf, off, count, true); } diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c index fe7fe678965b..5495537c60c2 100644 --- a/drivers/pci/proc.c +++ b/drivers/pci/proc.c @@ -13,6 +13,7 @@ #include #include #include +#include #include #include "pci.h" @@ -115,7 +116,11 @@ static ssize_t proc_bus_pci_write(struct file *file, const char __user *buf, struct pci_dev *dev = PDE_DATA(ino); int pos = *ppos; int size = dev->cfg_size; - int cnt; + int cnt, ret; + + ret = security_locked_down(LOCKDOWN_PCI_ACCESS); + if (ret) + return ret; if (pos >= size) return 0; @@ -196,6 +201,10 @@ static long proc_bus_pci_ioctl(struct file *file, unsigned int cmd, #endif /* HAVE_PCI_MMAP */ int ret = 0; + ret = security_locked_down(LOCKDOWN_PCI_ACCESS); + if (ret) + return ret; + switch (cmd) { case PCIIOC_CONTROLLER: ret = pci_domain_nr(dev->bus); @@ -238,7 +247,8 @@ 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) || + security_locked_down(LOCKDOWN_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..31e39558d49d 100644 --- a/drivers/pci/syscall.c +++ b/drivers/pci/syscall.c @@ -7,6 +7,7 @@ #include #include +#include #include #include #include "pci.h" @@ -90,7 +91,8 @@ 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) || + security_locked_down(LOCKDOWN_PCI_ACCESS)) return -EPERM; dev = pci_get_domain_bus_and_slot(0, bus, dfn); diff --git a/include/linux/security.h b/include/linux/security.h index 304a155a5628..8adbd62b7669 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -107,6 +107,7 @@ enum lockdown_reason { LOCKDOWN_DEV_MEM, LOCKDOWN_KEXEC, LOCKDOWN_HIBERNATION, + LOCKDOWN_PCI_ACCESS, LOCKDOWN_INTEGRITY_MAX, LOCKDOWN_CONFIDENTIALITY_MAX, }; diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c index a0996f75629f..655fe388e615 100644 --- a/security/lockdown/lockdown.c +++ b/security/lockdown/lockdown.c @@ -22,6 +22,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = { [LOCKDOWN_DEV_MEM] = "/dev/mem,kmem,port", [LOCKDOWN_KEXEC] = "kexec of unsigned images", [LOCKDOWN_HIBERNATION] = "hibernation", + [LOCKDOWN_PCI_ACCESS] = "direct PCI access", [LOCKDOWN_INTEGRITY_MAX] = "integrity", [LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality", };