From patchwork Sat Jun 22 00:03:40 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Garrett X-Patchwork-Id: 11010987 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 EDC9C924 for ; Sat, 22 Jun 2019 00:04:32 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id DF1A226E3D for ; Sat, 22 Jun 2019 00:04:32 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D37A628BB1; Sat, 22 Jun 2019 00:04:32 +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 4265226E3D for ; Sat, 22 Jun 2019 00:04:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726669AbfFVAEb (ORCPT ); Fri, 21 Jun 2019 20:04:31 -0400 Received: from mail-qk1-f202.google.com ([209.85.222.202]:34854 "EHLO mail-qk1-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726665AbfFVAEa (ORCPT ); Fri, 21 Jun 2019 20:04:30 -0400 Received: by mail-qk1-f202.google.com with SMTP id 5so9432245qki.2 for ; Fri, 21 Jun 2019 17:04:29 -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=QR1Fq3MnogoZDxR5LoHcfLT1JRgAByQ+Bas4Z8/9Vdo=; b=cfhgJlRMYlL1ZQu+27acnf30xFuMCjbXTCAainFoeEtW6sZfy4z78AwyGDy66Snw59 pvtbyWjFtVqv2AKhiP7OGS07Od6EaserX0vCQ10ANdg4TLN7ndS3gF8OdAbzxSMsZSjY sgeyCW+DZbTYK5bDNnjil5OmnI6NDxkWpYVsoDss5Tq0elODK37VxHU4y9hCNubVo7H9 D6Jc4/affqcgrEdydVrRLwyNXiUAVcnoLZVmNAKzcNEAxu/tKT5a4J7pWmeE/G0DMrk1 UjiODKe8fvrl0qgaiKwOCtBZVX6C122MMiRCGRrT/OHEGYG0c08Il4sj/O4286/d7H/A e7rw== 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=QR1Fq3MnogoZDxR5LoHcfLT1JRgAByQ+Bas4Z8/9Vdo=; b=kNFoFqLZWtLYYpC2wUdPOgaKYeuXI7+imGL9j54iQRS6wpuDuGmeL7ALDXJQaNqUvE qC/AN/Qx9jBJjxF+jV5ZXl2goWVg7xpbND5ag16Q9TB2E6YMYg6MY97jDZJlAYzddxE5 UD/aOLGUSnmjo5L5EyAihqKfAsbCfLzSr1o1tltiiIk2nFC+bcWZlY52pwK+H4QIxWQQ oKc9Zocrkci0YvnjOru46mA9iIdiBXn2tREX0gNWu5dHlJyAjQTVrbKRB9nC8YmB6LT0 MtaHuspYp/8qE9xtuCOPS2/leybIEFzvPQ7ciJWV7B4PjWADsrr4VAJKIgixbVdDLQsb HmCw== X-Gm-Message-State: APjAAAU9fEekgKwYpzqgNwiuSSX9NglAfs2YRkuG7Juektpj1eOvmgUE mEvIwcYxtVBTF6ceF/OE2oN+xSSOmpNjDmYBHVaCdA== X-Google-Smtp-Source: APXvYqzqeYXV9vwwXpTuqXyUuPT7+AwixwFvcs5ahBxR269UhwHGbFEprjzHgFntrzvSS2eF903JUTvnb8Dc9mAG5s87nw== X-Received: by 2002:a37:a98c:: with SMTP id s134mr109806733qke.176.1561161869518; Fri, 21 Jun 2019 17:04:29 -0700 (PDT) Date: Fri, 21 Jun 2019 17:03:40 -0700 In-Reply-To: <20190622000358.19895-1-matthewgarrett@google.com> Message-Id: <20190622000358.19895-12-matthewgarrett@google.com> Mime-Version: 1.0 References: <20190622000358.19895-1-matthewgarrett@google.com> X-Mailer: git-send-email 2.22.0.410.gd8fdbe21b5-goog Subject: [PATCH V34 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 , 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 Reviewed-by: Kees Cook --- 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 25794c27c7a4..e1011efb5a31 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; @@ -1165,6 +1170,11 @@ 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; @@ -1241,6 +1251,12 @@ 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 6fa1627ce08d..a72258d70407 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); @@ -237,7 +246,8 @@ 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 a051f21a1144..1b849f10dec6 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -86,6 +86,7 @@ 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 ce5b3da9bd09..e2ee8a16b94c 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", };