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[209.132.180.67]) by mx.google.com with ESMTP id c13si489893pjo.75.2019.08.07.17.08.46; Wed, 07 Aug 2019 17:09:01 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=dvTWxtC+; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389610AbfHHAH4 (ORCPT + 99 others); Wed, 7 Aug 2019 20:07:56 -0400 Received: from mail-qk1-f201.google.com ([209.85.222.201]:51424 "EHLO mail-qk1-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389580AbfHHAHy (ORCPT ); Wed, 7 Aug 2019 20:07:54 -0400 Received: by mail-qk1-f201.google.com with SMTP id s25so80594287qkj.18 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=kBVanVENjziOcNQSH4J5WrEuDGHLVqB/POCKYuJ0ksdD+hV/R5NmGsy5n+oD7CTJ27 3Rd6815b//S74XsX1ocUqY3NTX40urY4VKn3cJm1GlYabwE6crcbTgJMx6CLAquFr1kV dsOqQ/gEecCQ9+p6c22laRXBldHw4WDmlOTRPHtU2fYGHFz1aAgr5DVe6AEVq/GG21tM SPeDU71jL72eXdN2w5KarJk59wAUMiDYzyVm7rQtFkk9EOpMocq5P4SRfN+NUfhx9ltt yWU1hF8WZ6aKAja9VgDpuGbDu1KLFPoWxEMZAcGr6Ci5ZrAnxfYkGkIuO5Ksx5ov9Mlt faKw== X-Gm-Message-State: APjAAAX4BSj3neCYhS5vokA51a9V+7k5sUfi/mdjfUpqjOyKSusCg2Fz IgS8lkzP3WiNSstQpMlfyGvkm7WEOI4NHPr+1jkbag== 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 Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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", }; -- 2.22.0.770.g0f2c4a37fd-goog