From patchwork Mon May 24 17:18:12 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Rajat Jain X-Patchwork-Id: 12276689 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1ABA3C04FF3 for ; Mon, 24 May 2021 17:18:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E77436128D for ; Mon, 24 May 2021 17:18:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233423AbhEXRTw (ORCPT ); Mon, 24 May 2021 13:19:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42700 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233339AbhEXRTt (ORCPT ); Mon, 24 May 2021 13:19:49 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D9F8AC061756 for ; Mon, 24 May 2021 10:18:20 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id b66-20020a25cb450000b02905076ea039f1so38073449ybg.1 for ; Mon, 24 May 2021 10:18:20 -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=yez6SgYYJbzBwM8lGT34zkvFrIMgr7XcMvHVjqLf60g=; b=EYHzL69oxls6bfB0yaQSztoPhmTOAl9KcsFUH3ybC5MxCjfUxO22ckRJjR58D+G3cs 5DnLKDS8VLz2GkNA054XqMquLSJkCvuEKlQ+ZB5O0dP0j1Owm6arVweKsoh/n8eNqYiV 8xAX6aaO/oaSX/PPror1ltGbaQSIk9QM2jl7V8HZowfgRGrc7ajdk2GCDSZQmTa73P3o KTL55UNODO8XF9hyeZOD9oEMjDzuswWin/ReFTJQFECnbsaCvCdkuEfWTC9qS1Qg1SRj W6/yMmTbOmLE6/0cV+6qzr0m7mTZw4Usbg51r0mWx7OLQ5Ztad674SKB1V38M/TjDvAM j/zw== 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=yez6SgYYJbzBwM8lGT34zkvFrIMgr7XcMvHVjqLf60g=; b=HEv97eR9oMBpyYF8jUs9nt5e3CckHRxKD61EZ2fQLLra+ZSdHKnTBBMQWG87zJZaC6 tRRL3fs8xd6oOpUKl1rDbaR8IlYo41u9jsrdh671pcUsgJSEusXlhwbTO0bvSavtAxNk UsQ+sI4KNEqFZGqHSBfi6GvlyynJdO/3BR44cB14uq957fJkgXYVeN0Ogy2lzZFfCXpF 0msPR5SQYGJ7Jzj5VijW7qkiFyuUZ1h3bPZg8+2iv6OYEK/8DnNTkpPEncWS6NTiYjEi SWcC9MICHY5KueAa1wFPVzULzBjYWhWTmy2hS0beAOQvp4H0AZTI5woog611aIlaHCOR /V2g== X-Gm-Message-State: AOAM53249yAkMRv6xBA17X7lXswmqdyGOjmcINGrsXbMoULWUwy3nevl MDWHqBz2wFUYqlUoZWAiZWkXRimbdhXH X-Google-Smtp-Source: ABdhPJxGwPQ411ubW/ainhnHNC+oQQSAdwGPVk+CanmIo26sW7wk9cwK25bys72Pnl3wwtlKQ1SwgjR4hsVO X-Received: from rajat2.mtv.corp.google.com ([2620:15c:202:201:db02:e944:e89a:61ef]) (user=rajatja job=sendgmr) by 2002:a25:addc:: with SMTP id d28mr38556730ybe.448.1621876700066; Mon, 24 May 2021 10:18:20 -0700 (PDT) Date: Mon, 24 May 2021 10:18:12 -0700 In-Reply-To: <20210524171812.18095-1-rajatja@google.com> Message-Id: <20210524171812.18095-2-rajatja@google.com> Mime-Version: 1.0 References: <20210524171812.18095-1-rajatja@google.com> X-Mailer: git-send-email 2.31.1.818.g46aad6cb9e-goog Subject: [PATCH v5 2/2] PCI: Add sysfs "removable" attribute From: Rajat Jain To: Greg Kroah-Hartman , "Rafael J. Wysocki" , Bjorn Helgaas , Alan Stern , Rajat Jain , linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-usb@vger.kernel.org, helgaas@kernel.org, Oliver Neukum , David Laight , " =?utf-8?q?Krzysztof_Wilczy=C5=84ski?= " Cc: rajatxjain@gmail.com, jsbarnes@google.com, dtor@google.com Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org A PCI device is "external_facing" if it's a Root Port with the ACPI "ExternalFacingPort" property or if it has the DT "external-facing" property. We consider everything downstream from such a device to be removable by user. We're mainly concerned with consumer platforms with user accessible Thunderbolt ports that are vulnerable to DMA attacks, and we expect those ports to be identified by firmware as "ExternalFacingPort". Devices in traditional hotplug slots can technically be removed, but the expectation is that unless the port is marked with "ExternalFacingPort", such devices are less accessible to user / may not be removed by end user, and thus not exposed as "removable" to userspace. This can be used to implement userspace policies tailored for user removable devices. Eg usage: https://chromium-review.googlesource.com/c/chromiumos/platform2/+/2591812 https://chromium-review.googlesource.com/c/chromiumos/platform2/+/2795038 (code uses such an attribute to remove external PCI devices or disable features on them as needed by the policy desired) Signed-off-by: Rajat Jain Acked-by: Bjorn Helgaas --- v5: - Add Bjorn's Ack. v4: - code comments, commit log updates - Make "removable" attribute show up only under devices that are really removable. v3: - commit log updated - Rename set_pci_dev_removable() -> pci_set_removable() - Call it after applying early PCI quirks. v2: Add documentation .../ABI/testing/sysfs-devices-removable | 3 ++- drivers/pci/probe.c | 22 +++++++++++++++++++ 2 files changed, 24 insertions(+), 1 deletion(-) diff --git a/Documentation/ABI/testing/sysfs-devices-removable b/Documentation/ABI/testing/sysfs-devices-removable index acf7766e800b..bda6c320c8d3 100644 --- a/Documentation/ABI/testing/sysfs-devices-removable +++ b/Documentation/ABI/testing/sysfs-devices-removable @@ -14,4 +14,5 @@ Description: Currently this is only supported by USB (which infers the information from a combination of hub descriptor bits and - platform-specific data such as ACPI). + platform-specific data such as ACPI) and PCI (which gets this + from ACPI / device tree). diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 3a62d09b8869..812e0d7fd7a7 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -1575,6 +1575,26 @@ static void set_pcie_untrusted(struct pci_dev *dev) dev->untrusted = true; } +static void pci_set_removable(struct pci_dev *dev) +{ + struct pci_dev *parent = pci_upstream_bridge(dev); + + /* + * We (only) consider everything downstream from an external_facing + * device to be removable by the user. We're mainly concerned with + * consumer platforms with user accessible thunderbolt ports that are + * vulnerable to DMA attacks, and we expect those ports to be marked by + * the firmware as external_facing. Devices in traditional hotplug + * slots can technically be removed, but the expectation is that unless + * the port is marked with external_facing, such devices are less + * accessible to user / may not be removed by end user, and thus not + * exposed as "removable" to userspace. + */ + if (parent && + (parent->external_facing || dev_is_removable(&parent->dev))) + dev_set_removable(&dev->dev, DEVICE_REMOVABLE); +} + /** * pci_ext_cfg_is_aliased - Is ext config space just an alias of std config? * @dev: PCI device @@ -1822,6 +1842,8 @@ int pci_setup_device(struct pci_dev *dev) /* Early fixups, before probing the BARs */ pci_fixup_device(pci_fixup_early, dev); + pci_set_removable(dev); + pci_info(dev, "[%04x:%04x] type %02x class %#08x\n", dev->vendor, dev->device, dev->hdr_type, dev->class);