From patchwork Wed Jul 31 22:15:59 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Garrett X-Patchwork-Id: 11069693 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 6C3C51395 for ; Wed, 31 Jul 2019 22:19:23 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5F21027F17 for ; Wed, 31 Jul 2019 22:19:23 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 5342027F81; Wed, 31 Jul 2019 22:19:23 +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 BDA5727F17 for ; Wed, 31 Jul 2019 22:19:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728511AbfGaWTV (ORCPT ); Wed, 31 Jul 2019 18:19:21 -0400 Received: from mail-pl1-f202.google.com ([209.85.214.202]:43064 "EHLO mail-pl1-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731256AbfGaWQz (ORCPT ); Wed, 31 Jul 2019 18:16:55 -0400 Received: by mail-pl1-f202.google.com with SMTP id t2so38328936plo.10 for ; Wed, 31 Jul 2019 15:16:54 -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=OSQfdUjsKNzN31+bhcUXLr2H8Ocf38HBXPBklzHGY4NHM5jtawY+aqnedkfaXFZ0CH bnrxhckspK+Dl2WO5zPvm4mIVlAqzNa6JXDwRhYEqAg0nADrIuzMJ99IW7CBMC0z06cT XaVM5l2ElJjj+URRBbOga5Os28t1bLbOtSwQtIE+ij9v4hybvyoiXs5ll9mxRs6PlMpq /vN8vAqK0ZDwqqLRWoXnIfLPbUjKbN7YPC21GMErPsgBxVLl25dtev+CZ42wiW3SO7lZ oSgtUizV2FJn8NR5XwBoh3M6bWa7Pal2CGantvm3rpWwH0EEOGsg7Y4ap6b13GTY89ZS 5RVA== 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=rsXB4h0Ih37hjpz0v17pBLtfGulSP8CLKKJbISqw2Yq1Ufv8c1xJUhLxhJzkZXHJ9m l3JfjogyBD+6hJhWxYPMfkvzq25XGr2pB8iHhahaGx+/kFBh54Oee/dT4crnzosK8akS Cylej/EGhMb2jCqKoyuuO60NyFn4MPQxU9J9zBDv5yBfZJKqU+2Note7xoVdCNIghFFH SImg7waMFBkFJNaD0iVjCsDHqF14YEr+lOBAKq29PB4TfQgr4Xqh9uBaPX/+ByqJhLFQ /k3JdqlNhTcCFtvVGUOjGs8ClkW2mUkQGqrndIktC+TkuSzpzvDP/C6bnMAP2f4+rAdG iQLg== X-Gm-Message-State: APjAAAUh+SMEZ6++LzeZjuyaudkAOBXgFMfCMydLPzXZXi92An2RQRwB th8NRqRR45sTgZ+t7Z45d6KfUQJfkTRUoQZEkVVO8g== X-Google-Smtp-Source: APXvYqyS6YBKB93OOHHm+oxngalxRdvpUX2H1ET3d0/GBi0Heyba67cmqacKd5xZ/ghnAHwFoSGfoLlRBb6KosWk16Qoqg== X-Received: by 2002:a65:6850:: with SMTP id q16mr80028747pgt.423.1564611414229; Wed, 31 Jul 2019 15:16:54 -0700 (PDT) Date: Wed, 31 Jul 2019 15:15:59 -0700 In-Reply-To: <20190731221617.234725-1-matthewgarrett@google.com> Message-Id: <20190731221617.234725-12-matthewgarrett@google.com> Mime-Version: 1.0 References: <20190731221617.234725-1-matthewgarrett@google.com> X-Mailer: git-send-email 2.22.0.770.g0f2c4a37fd-goog Subject: [PATCH V37 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: 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 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", };