Linux-PCI Archive on lore.kernel.org
 help / color / Atom feed
From: Rajat Jain <rajatja@google.com>
To: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>,
	Bjorn Helgaas <helgaas@kernel.org>,
	linux-pci <linux-pci@vger.kernel.org>,
	Jean-Philippe Brucker <jean-philippe@linaro.org>,
	Prashant Malani <pmalani@google.com>,
	Benson Leung <bleung@google.com>, Todd Broch <tbroch@google.com>,
	Alex Levin <levinale@google.com>,
	Mattias Nissler <mnissler@google.com>,
	Zubin Mithra <zsm@google.com>, Rajat Jain <rajatxjain@gmail.com>,
	"Keany, Bernie" <bernie.keany@intel.com>,
	Aaron Durbin <adurbin@google.com>,
	Diego Rivas <diegorivas@google.com>,
	Duncan Laurie <dlaurie@google.com>,
	Furquan Shaikh <furquan@google.com>,
	Jesse Barnes <jsbarnes@google.com>
Subject: Re: [RFC] Restrict the untrusted devices, to bind to only a set of "whitelisted" drivers
Date: Wed, 6 May 2020 11:51:24 -0700
Message-ID: <CACK8Z6EF6pbFwWDTUiCKFs0NY47fmdRVOopR-fOPagmKsUpfLQ@mail.gmail.com> (raw)
In-Reply-To: <20200505123306.GC487496@lahna.fi.intel.com>

On Tue, May 5, 2020 at 5:33 AM Mika Westerberg
<mika.westerberg@linux.intel.com> wrote:
>
> On Fri, May 01, 2020 at 04:07:10PM -0700, Rajat Jain wrote:
> > Hi,
>
> Hi,
>
> > Currently, the PCI subsystem marks the PCI devices as "untrusted", if
> > the firmware asks it to:
> >
> > 617654aae50e ("PCI / ACPI: Identify untrusted PCI devices")
> > 9cb30a71acd4 ("PCI: OF: Support "external-facing" property")
> >
> > An "untrusted" device indicates a (likely external facing) device that
> > may be malicious, and can trigger DMA attacks on the system. It may
> > also try to exploit any vulnerabilities exposed by the driver, that
> > may allow it to read/write unintended addresses in the host (e.g. if
> > DMA buffers for the device, share memory pages with other driver data
> > structures or code etc).
> >
> > High Level proposal
> > ===============
> > Currently, the "untrusted" device property is used as a hint to enable
> > IOMMU restrictions (on Intel), disable ATS (on ARM) etc. We'd like to
> > go a step further, and allow the administrator to build a list of
> > whitelisted drivers for these "untrusted" devices. This whitelist of
> > drivers are the ones that he trusts enough to have little or no
> > vulnerabilities. (He may have built this list of whitelisted drivers
> > by a combination of code analysis of drivers, or by extensive testing
> > using PCIe fuzzing etc). We propose that the administrator be allowed
> > to specify this list of whitelisted drivers to the kernel, and the PCI
> > subsystem to impose this behavior:
> >
> > 1) The "untrusted" devices can bind to only "whitelisted drivers".
> > 2) The other devices (i.e. dev->untrusted=0) can bind to any driver.
> >
> > Of course this behavior is to be imposed only if such a whitelist is
> > provided by the administrator.
> >
> > Details
> > ======
> >
> > 1) A kernel argument ("pci.impose_driver_whitelisting") to enable
> > imposing of whitelisting by PCI subsystem.
>
> In addition this could be a Kconfig option, I think.
>
> > 2) Add a flag ("whitelisted") in struct pci_driver to indicate whether
> > the driver is whitelisted.
> >
> > 3) Use the driver's "whitelisted" flag and the device's "untrusted"
> > flag, to make a decision about whether to bind or not in
> > pci_bus_match() or similar.
> >
> > 4) A mechanism to allow the administrator to specify the whitelist of
> > drivers. I think this needs more thought as there are multiple
> > options.
> >
> > a) Expose individual driver's "whitelisted" flag to userspace so a
> > boot script can whitelist that driver. There are questions that still
> > need answered though e.g. what to do about the devices that may have
> > already been enumerated and rejected by then? What to do with the
> > already bound devices, if the user changes a driver to remove it from
> > the whitelist. etc.
> >
> >       b) Provide a way to specify the whitelist via the kernel command
> > line. Accept a ("pci.whitelist") kernel parameter which is a comma
> > separated list of driver names (just like "module_blacklist"), and
> > then use it to initialize each driver's "whitelisted" flag as the
> > drivers are registered. Essentially this would mean that the whitelist
> > of devices cannot be changed after boot.
> >
> > To me (b) looks a better option but I think a future requirement would
> > be the ability to remove the drivers from the whitelist after boot
> > (adding drivers to whitelist at runtime may not be that critical IMO)
>
> What about adding "module.whitelisted" parameter in the same way than we
> have for example "module.dyndbg"? Then you can pass these in the command
> line, during module load time and also trough /sys/module/.

Sure we can do that.

However, I suspect ability to add to the whitelist after booting up
might be frowned upon. May be if we do that, we can somehow ensure
that the drivers can only be removed from the whitelist, and not
added.

Thanks,

Rajat

  reply index

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-01 23:07 Rajat Jain
2020-05-04 11:47 ` Jean-Philippe Brucker
2020-05-04 11:59   ` Jean-Philippe Brucker
2020-05-04 19:17     ` Rajat Jain
2020-05-05 12:33 ` Mika Westerberg
2020-05-06 18:51   ` Rajat Jain [this message]
2020-05-11 20:31 ` Rajat Jain
2020-05-13 15:19 ` Bjorn Helgaas
2020-05-13 21:26   ` Rajat Jain
2020-05-14 13:42     ` Mika Westerberg
2020-05-14 19:12     ` Raj, Ashok
2020-05-15  2:18       ` Rajat Jain
2020-05-26 16:30         ` Rajat Jain
2020-06-01 23:25           ` Bjorn Helgaas
2020-06-02  5:06             ` Greg Kroah-Hartman
2020-06-03  2:27               ` Rajat Jain
2020-06-03  6:07                 ` Greg Kroah-Hartman
2020-06-03 11:51                   ` Rajat Jain
2020-06-03 12:16                     ` Greg Kroah-Hartman
2020-06-03 12:57                       ` Rajat Jain
2020-06-03 13:29                         ` Greg Kroah-Hartman
2020-06-04 19:38                       ` Rajat Jain
2020-06-05  8:02                         ` Greg Kroah-Hartman
2020-06-06  1:08                           ` Rajat Jain
2020-06-07 11:36                             ` Greg Kroah-Hartman
2020-06-08 17:03                               ` Jesse Barnes
2020-06-08 17:50                                 ` Greg Kroah-Hartman
2020-06-08 18:29                                   ` Jesse Barnes
2020-06-08 18:41                                     ` Rajat Jain
2020-06-09  9:54                                       ` Greg Kroah-Hartman
2020-06-30 21:46                                         ` Pavel Machek
2020-06-09  5:57                                     ` Greg Kroah-Hartman
2020-06-30 21:45                                 ` Pavel Machek
2020-07-01  6:54                                   ` Greg Kroah-Hartman
2020-07-01  8:47                                     ` Pavel Machek
2020-07-01 10:57                                       ` Greg Kroah-Hartman
2020-07-01 11:08                                         ` Pavel Machek
2020-06-09 21:04                               ` Bjorn Helgaas
2020-06-09 23:23                                 ` Rajat Jain
2020-06-10  0:04                                   ` Bjorn Helgaas
2020-06-10  0:30                                     ` Rajat Jain
2020-06-10 20:17                                       ` Rajat Jain
2020-06-10 23:09                                         ` Bjorn Helgaas
2020-06-10 23:01                                       ` Bjorn Helgaas
2020-06-10 23:46                                         ` Rajat Jain
2020-06-10  7:13                                   ` Greg Kroah-Hartman
2020-06-10  1:34                                 ` Oliver O'Halloran
2020-06-10 19:57                                   ` Rajat Jain
2020-06-16  1:24                                     ` Rajat Jain
2020-06-10  7:12                                 ` Greg Kroah-Hartman
2020-05-15 12:44     ` Joerg Roedel

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=CACK8Z6EF6pbFwWDTUiCKFs0NY47fmdRVOopR-fOPagmKsUpfLQ@mail.gmail.com \
    --to=rajatja@google.com \
    --cc=adurbin@google.com \
    --cc=bernie.keany@intel.com \
    --cc=bhelgaas@google.com \
    --cc=bleung@google.com \
    --cc=diegorivas@google.com \
    --cc=dlaurie@google.com \
    --cc=furquan@google.com \
    --cc=helgaas@kernel.org \
    --cc=jean-philippe@linaro.org \
    --cc=jsbarnes@google.com \
    --cc=levinale@google.com \
    --cc=linux-pci@vger.kernel.org \
    --cc=mika.westerberg@linux.intel.com \
    --cc=mnissler@google.com \
    --cc=pmalani@google.com \
    --cc=rajatxjain@gmail.com \
    --cc=tbroch@google.com \
    --cc=zsm@google.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-PCI Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-pci/0 linux-pci/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-pci linux-pci/ https://lore.kernel.org/linux-pci \
		linux-pci@vger.kernel.org
	public-inbox-index linux-pci

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-pci


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git