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From: Saravana Kannan via iommu <iommu@lists.linux-foundation.org>
To: Rajat Jain <rajatja@google.com>
Cc: Todd Broch <tbroch@google.com>,
	Linux PCI <linux-pci@vger.kernel.org>,
	lalithambika.krishnakumar@intel.com,
	Heikki Krogerus <heikki.krogerus@linux.intel.com>,
	Diego Rivas <diegorivas@google.com>,
	Jean-Philippe Brucker <jean-philippe@linaro.org>,
	Furquan Shaikh <furquan@google.com>,
	Raj Ashok <ashok.raj@intel.com>,
	ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
	Christian Kellner <christian@kellner.me>,
	Mattias Nissler <mnissler@google.com>,
	Jesse Barnes <jsbarnes@google.com>, Len Brown <lenb@kernel.org>,
	Rajat Jain <rajatxjain@gmail.com>,
	Prashant Malani <pmalani@google.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Aaron Durbin <adurbin@google.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Mika Westerberg <mika.westerberg@linux.intel.com>,
	Bernie Keany <bernie.keany@intel.com>,
	Duncan Laurie <dlaurie@google.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	LKML <linux-kernel@vger.kernel.org>,
	iommu@lists.linux-foundation.org, Arnd Bergmann <arnd@arndb.de>,
	oohall@gmail.com, Benson Leung <bleung@google.com>,
	David Woodhouse <dwmw2@infradead.org>,
	Alex Levin <levinale@google.com>
Subject: Re: [PATCH v2 5/7] driver core: Add device location to "struct device" and expose it in sysfs
Date: Tue, 30 Jun 2020 10:43:37 -0700	[thread overview]
Message-ID: <CAGETcx9hgV70DVdbOvCF+tO4b-6+1JzN1_OmPmnWjj9qJhB_dw@mail.gmail.com> (raw)
In-Reply-To: <20200630044943.3425049-6-rajatja@google.com>

On Mon, Jun 29, 2020 at 9:49 PM Rajat Jain <rajatja@google.com> wrote:
>
> Add a new (optional) field to denote the physical location of a device
> in the system, and expose it in sysfs. This was discussed here:
> https://lore.kernel.org/linux-acpi/20200618184621.GA446639@kroah.com/
>
> (The primary choice for attribute name i.e. "location" is already
> exposed as an ABI elsewhere, so settled for "site"). Individual buses
> that want to support this new attribute can opt-in by setting a flag in
> bus_type, and then populating the location of device while enumerating
> it.
>
> Signed-off-by: Rajat Jain <rajatja@google.com>
> ---
> v2: (Initial version)
>
>  drivers/base/core.c        | 35 +++++++++++++++++++++++++++++++
>  include/linux/device.h     | 42 ++++++++++++++++++++++++++++++++++++++
>  include/linux/device/bus.h |  8 ++++++++
>  3 files changed, 85 insertions(+)
>

<snip> I'm not CC'ed in 4/7, so just replying

> diff --git a/include/linux/device.h b/include/linux/device.h
> index 15460a5ac024a..a4143735ae712 100644
> --- a/include/linux/device.h
> +++ b/include/linux/device.h
> @@ -428,6 +428,31 @@ enum dl_dev_state {
>         DL_DEV_UNBINDING,
>  };
>
> +/**
> + * enum device_site - Physical location of the device in the system.
> + * The semantics of values depend on subsystem / bus:
> + *
> + * @SITE_UNKNOWN:  Location is Unknown (default)
> + *
> + * @SITE_INTERNAL: Device is internal to the system, and cannot be (easily)
> + *                 removed. E.g. SoC internal devices, onboard soldered
> + *                 devices, internal M.2 cards (that cannot be removed
> + *                 without opening the chassis).
> + * @SITE_EXTENDED: Device sits an extension of the system. E.g. devices
> + *                 on external PCIe trays, docking stations etc. These
> + *                 devices may be removable, but are generally housed
> + *                 internally on an extension board, so they are removed
> + *                 only when that whole extension board is removed.
> + * @SITE_EXTERNAL: Devices truly external to the system (i.e. plugged on
> + *                 an external port) that may be removed or added frequently.
> + */
> +enum device_site {
> +       SITE_UNKNOWN = 0,
> +       SITE_INTERNAL,
> +       SITE_EXTENDED,
> +       SITE_EXTERNAL,
> +};
> +
>  /**
>   * struct dev_links_info - Device data related to device links.
>   * @suppliers: List of links to supplier devices.
> @@ -513,6 +538,7 @@ struct dev_links_info {
>   *             device (i.e. the bus driver that discovered the device).
>   * @iommu_group: IOMMU group the device belongs to.
>   * @iommu:     Per device generic IOMMU runtime data
> + * @site:      Physical location of the device w.r.t. the system
>   *
>   * @offline_disabled: If set, the device is permanently online.
>   * @offline:   Set after successful invocation of bus type's .offline().
> @@ -613,6 +639,8 @@ struct device {
>         struct iommu_group      *iommu_group;
>         struct dev_iommu        *iommu;
>
> +       enum device_site        site;   /* Device physical location */
> +
>         bool                    offline_disabled:1;
>         bool                    offline:1;
>         bool                    of_node_reused:1;
> @@ -806,6 +834,20 @@ static inline bool dev_has_sync_state(struct device *dev)
>         return false;
>  }
>
> +static inline int dev_set_site(struct device *dev, enum device_site site)
> +{
> +       if (site < SITE_UNKNOWN || site > SITE_EXTERNAL)
> +               return -EINVAL;
> +
> +       dev->site = site;
> +       return 0;
> +}
> +
> +static inline bool dev_is_external(struct device *dev)
> +{
> +       return dev->site == SITE_EXTERNAL;
> +}

I'm not CC'ed in the rest of the patches in this series, so just
responding here. I see you use this function in patch 6/7 to decide if
the PCI device is trusted. Anything other than EXTERNAL is being
treated as trusted. I'd argue that anything that's not internal should
be distrusted. For example, I can have a hacked up laptop dock that I
can share with you when you visit my home/office and now you are
trusting it when you shouldn't be.

Also, "UNKNOWN" is treated as trusted in patch 6/7. I'm guessing this
is because some of the devices might not have the info in their
firmware? At which point, this feature isn't even protecting all the
PCI ports properly? This adds to Greg point that this should be a
userspace policy so that it can override whatever is wrong/missing in
the firmware.

-Saravana
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  parent reply	other threads:[~2020-06-30 17:44 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-30  4:49 [PATCH v2 0/7] Tighten PCI security, expose dev location in sysfs Rajat Jain via iommu
2020-06-30  4:49 ` [PATCH v2 1/7] PCI: Keep the ACS capability offset in device Rajat Jain via iommu
2020-07-06 15:58   ` Bjorn Helgaas
2020-07-06 22:16     ` Rajat Jain via iommu
2020-07-06 23:18       ` Bjorn Helgaas
2020-06-30  4:49 ` [PATCH v2 2/7] PCI: Set "untrusted" flag for truly external devices only Rajat Jain via iommu
2020-06-30  7:38   ` Lu Baolu
2020-06-30  7:55   ` Greg Kroah-Hartman
2020-07-06 16:41     ` Bjorn Helgaas
2020-07-06 18:48       ` Greg Kroah-Hartman
2020-07-06 16:38   ` Bjorn Helgaas
2020-07-06 22:31     ` Rajat Jain via iommu
2020-07-06 23:30       ` Bjorn Helgaas
2020-07-06 23:40         ` Rajat Jain via iommu
2020-06-30  4:49 ` [PATCH v2 3/7] PCI/ACS: Enable PCI_ACS_TB for untrusted/external-facing devices Rajat Jain via iommu
2020-07-06 16:45   ` Bjorn Helgaas
2020-07-06 23:12     ` Rajat Jain via iommu
2020-07-06 17:07   ` Bjorn Helgaas
2020-07-06 23:19     ` Rajat Jain via iommu
2020-06-30  4:49 ` [PATCH v2 4/7] PCI: Add device even if driver attach failed Rajat Jain via iommu
2020-06-30  8:02   ` Greg Kroah-Hartman
2020-07-06 23:35     ` Rajat Jain via iommu
2020-06-30  4:49 ` [PATCH v2 5/7] driver core: Add device location to "struct device" and expose it in sysfs Rajat Jain via iommu
2020-06-30  8:01   ` Greg Kroah-Hartman
2020-06-30 10:49   ` Heikki Krogerus
2020-06-30 12:52     ` Greg Kroah-Hartman
2020-06-30 13:00       ` Rafael J. Wysocki
2020-06-30 15:38         ` Greg Kroah-Hartman
2020-06-30 16:08           ` Rafael J. Wysocki
2020-06-30 17:00             ` Greg Kroah-Hartman
2020-07-01 18:06               ` Rajat Jain via iommu
2020-07-02  5:23                 ` Oliver O'Halloran
2020-07-02  7:32                   ` Greg Kroah-Hartman
2020-07-02  8:40                     ` Oliver O'Halloran
2020-07-02  8:52                       ` Greg Kroah-Hartman
2020-07-02  8:53                         ` Greg Kroah-Hartman
2020-07-07  6:03                   ` Rajat Jain via iommu
2020-06-30 17:43   ` Saravana Kannan via iommu [this message]
2020-06-30  4:49 ` [PATCH v2 6/7] PCI: Move pci_dev->untrusted logic to use device location instead Rajat Jain via iommu
2020-06-30  7:39   ` Lu Baolu
2020-06-30  4:49 ` [PATCH v2 7/7] PCI: Add parameter to disable attaching external devices Rajat Jain via iommu
2020-07-04 11:44 ` [PATCH v2 0/7] Tighten PCI security, expose dev location in sysfs Pavel Machek
2020-07-06 22:18   ` Rajat Jain via iommu

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