From patchwork Tue Aug 20 00:17:47 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Garrett X-Patchwork-Id: 11102381 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 78EA41395 for ; Tue, 20 Aug 2019 00:18:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4ECE722CF8 for ; Tue, 20 Aug 2019 00:18:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="NH7bfyD5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729007AbfHTASk (ORCPT ); Mon, 19 Aug 2019 20:18:40 -0400 Received: from mail-vs1-f73.google.com ([209.85.217.73]:42636 "EHLO mail-vs1-f73.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728998AbfHTASj (ORCPT ); Mon, 19 Aug 2019 20:18:39 -0400 Received: by mail-vs1-f73.google.com with SMTP id g1so1387722vso.9 for ; Mon, 19 Aug 2019 17:18:39 -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=C21FECnausr3Tl5okiJoQyTfXKFmIyPVDnhM6LCvplE=; b=NH7bfyD5O+gMXQWiRJKY74n3aIL9gst/DgjEm7lzZ+DlpZ6d+uwgt5b3pnxuJZGuqt nGwavCYuxnDNUBKXsw8mf/7bnSf5H5Rp0lUsE9QwG5vSOHS1WIr+dJM8+IGcqBQVgAgv RR8ok4Qe/MQsYEsjVVvZ0pHppnTiHmt/0fCQut5r7f33QGlPhtUs23InXWb8oa/QElos 0kHHFqTseiw/1hff9/LiaTJD0DkxK1VLmsFRvXL1Aix9SEcLFZqeRJtUo6JrVaeEQ3uF dbLGcqVdOGta+eIpB0Sa0qDDg2NWpi1/FlmsOfrWhUCE/T+f8sYfu6rDTgzYNPDbdNJQ HvhA== 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=C21FECnausr3Tl5okiJoQyTfXKFmIyPVDnhM6LCvplE=; b=OQJaD7VxSRYobYNGKQ/Bl4zkk7CrH3/gIKVhYoPvfnS5KpeRSfIAsCMw+x39zd1SMG FBZVhiPOw6NlB6iJFWc/dHXAWhJW8iCiSHHUz34XFZm0d6PCzgfsLpwmfuQK28SY1Rcl 2tnWn7tHnys1VYElTD2+sfZNf95MJTx41vJ3T9q3OI+sSmFXHQXvwyigUk2aghrHVf2J 49Q2piXZ8jJcYTwm5WToa98jeVdpEmlnohm+zEYyxzmnN14KvuyjBZzrkY4DEApOUyZq hB9DZy0IYwFZdaX+YERqNe93aNB8a5i8viqWTwLO8DYI0z005dyuFDxyoJhfvgBkxeup 1u6w== X-Gm-Message-State: APjAAAVEVamDtIEoGBFWXvva060byyyUlBcz6x0PVqDnu/5EIkBAt1VA kD4QqvLQUWFAqpM7Ht+59vrE/hVIPyLh2jT/W5pdEw== X-Google-Smtp-Source: APXvYqxN9EDYRByV2JMtzYzTa/IUcXtjUmQL77YxgWlXkE42Mz+D6/SFU+9rI4k9OcYzBwdXSj9Y9wb9pUwh8JDeCKt24w== X-Received: by 2002:a05:6102:24c:: with SMTP id a12mr15472758vsq.226.1566260318809; Mon, 19 Aug 2019 17:18:38 -0700 (PDT) Date: Mon, 19 Aug 2019 17:17:47 -0700 In-Reply-To: <20190820001805.241928-1-matthewgarrett@google.com> Message-Id: <20190820001805.241928-12-matthewgarrett@google.com> Mime-Version: 1.0 References: <20190820001805.241928-1-matthewgarrett@google.com> X-Mailer: git-send-email 2.23.0.rc1.153.gdeed80330f-goog Subject: [PATCH V40 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: 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 Signed-off-by: James Morris --- 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 6d27475e39b2..ec103a7e13fc 100644 --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -903,6 +903,11 @@ 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; @@ -1164,6 +1169,11 @@ 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; @@ -1240,6 +1250,12 @@ 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 445b51db75b0..e29b0d5ced62 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 80ac7fb27aa9..2b763f0ee352 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 3462f7edcaac..410e90eda848 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", };