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From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
To: Arvind Sankar <nivedita@alum.mit.edu>
Cc: Matthew Garrett <mjg59@google.com>,
	Ard Biesheuvel <ardb@kernel.org>,
	linux-efi <linux-efi@vger.kernel.org>,
	Hans de Goede <hdegoede@redhat.com>,
	Ingo Molnar <mingo@kernel.org>, Andy Lutomirski <luto@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH v2 21/21] efi: Allow disabling PCI busmastering on bridges during boot
Date: Mon, 23 Dec 2019 16:58:26 +0100	[thread overview]
Message-ID: <CAKv+Gu9kFVFdkaOGP2EYACa7eo4pTTKFif9ZgQ+uKnoKcsrmgQ@mail.gmail.com> (raw)
In-Reply-To: <20191223154648.GA10522@rani.riverdale.lan>

On Mon, 23 Dec 2019 at 16:46, Arvind Sankar <nivedita@alum.mit.edu> wrote:
>
> On Mon, Dec 23, 2019 at 03:02:40PM +0100, Ard Biesheuvel wrote:
> >
> > Practically, on PCIe systems, PCI/PCI bridges are the only thing we
> > need to care about, since that is how PCIe root ports are modelled.
>
> If I'm interpreting my lspci output correctly, I have a PCI/ISA bridge
> on bus 0 that's not behind a PCI/PCI bridge. Device 1f.0 below is the
> PCI/ISA bridge.

Yeah, this is the LPC controller, right? What devices are actually on
that bus that are not closely tied to the chipset?

> Devices 1-3 are the CPU root ports and 1c.* are the
> chipset root ports.
>

Right.

> Also, what about for eg, the USB or SATA controllers? I know that
> someone had said earlier that disabling BM on endpoints is pointless as
> malicious endpoints could just re-enable it, but is it not possible for
> malicious USB devices/SATA devices to try to use DMA through those
> controllers? ie if we trust the controllers since they're on-board, but
> not necessarily the devices behind them, wouldn't it still be worth it
> to disable BM on the controllers too?
>

At this point, it probably makes sense to clarify what the threat
model is. I have been assuming (but Matthew should confirm) that we're
primarily concerned with DMA attacks over, e.g., Thunderbolt ports, in
which case managing the BM bit at the root port level should be
sufficient.

If there are other things we want to address (or if my assumption was
incorrect), we should clarify this first, before deciding what the
right mitigation would be.

> $ lspci -tv -s 0:0:
> -[0000:00]-+-00.0  Intel Corporation Xeon E7 v4/Xeon E5 v4/Xeon E3 v4/Xeon D DMI2
>            +-01.0-[01]--
>            +-01.1-[02]--
>            +-02.0-[03]--
>            +-02.2-[04]--
>            +-03.0-[05]--
>            +-03.2-[06-09]--
>            +-05.0  Intel Corporation Xeon E7 v4/Xeon E5 v4/Xeon E3 v4/Xeon D Map/VTd_Misc/System Management
>            +-05.1  Intel Corporation Xeon E7 v4/Xeon E5 v4/Xeon E3 v4/Xeon D IIO Hot Plug
>            +-05.2  Intel Corporation Xeon E7 v4/Xeon E5 v4/Xeon E3 v4/Xeon D IIO RAS/Control Status/Global Errors
>            +-05.4  Intel Corporation Xeon E7 v4/Xeon E5 v4/Xeon E3 v4/Xeon D I/O APIC
>            +-11.0  Intel Corporation C610/X99 series chipset SPSR
>            +-11.4  Intel Corporation C610/X99 series chipset sSATA Controller [AHCI mode]
>            +-14.0  Intel Corporation C610/X99 series chipset USB xHCI Host Controller
>            +-16.0  Intel Corporation C610/X99 series chipset MEI Controller #1
>            +-16.1  Intel Corporation C610/X99 series chipset MEI Controller #2
>            +-1a.0  Intel Corporation C610/X99 series chipset USB Enhanced Host Controller #2
>            +-1b.0  Intel Corporation C610/X99 series chipset HD Audio Controller
>            +-1c.0-[0a]--
>            +-1c.2-[0b]--
>            +-1c.3-[0c]--
>            +-1c.4-[0d]--
>            +-1c.7-[0e-0f]--
>            +-1d.0  Intel Corporation C610/X99 series chipset USB Enhanced Host Controller #1
>            +-1f.0  Intel Corporation C610/X99 series chipset LPC Controller
>            +-1f.2  Intel Corporation C610/X99 series chipset 6-Port SATA Controller [AHCI mode]
>            \-1f.3  Intel Corporation C610/X99 series chipset SMBus Controller
>

  reply	other threads:[~2019-12-23 15:58 UTC|newest]

Thread overview: 87+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-18 17:01 [PATCH v2 00/21] efi/x86: confine type unsafe casting to mixed mode Ard Biesheuvel
2019-12-18 17:01 ` [PATCH v2 01/21] efi/libstub: remove unused __efi_call_early() macro Ard Biesheuvel
2019-12-18 17:01 ` [PATCH v2 02/21] efi/x86: rename efi_is_native() to efi_is_mixed() Ard Biesheuvel
2019-12-18 17:01 ` [PATCH v2 03/21] efi/libstub: use a helper to iterate over a EFI handle array Ard Biesheuvel
2019-12-18 17:01 ` [PATCH v2 04/21] efi/libstub: extend native protocol definitions with mixed_mode aliases Ard Biesheuvel
2019-12-18 17:01 ` [PATCH v2 05/21] efi/libstub: distinguish between native/mixed not 32/64 bit Ard Biesheuvel
2019-12-18 17:01 ` [PATCH v2 06/21] efi/libstub/x86: use mixed mode helpers to populate efi_config Ard Biesheuvel
2019-12-18 17:01 ` [PATCH v2 07/21] efi/libstub: drop explicit 32/64-bit protocol definitions Ard Biesheuvel
2019-12-18 17:01 ` [PATCH v2 08/21] efi/libstub: use stricter typing for firmware function pointers Ard Biesheuvel
2019-12-18 17:01 ` [PATCH v2 09/21] efi/libstub: annotate firmware routines as __efiapi Ard Biesheuvel
2019-12-18 17:01 ` [PATCH v2 10/21] efi/libstub/x86: avoid thunking for native firmware calls Ard Biesheuvel
2019-12-21 21:22   ` Hans de Goede
2019-12-22 12:02     ` Ard Biesheuvel
2019-12-22 12:37       ` Ard Biesheuvel
2019-12-22 12:46       ` Andy Lutomirski
2019-12-22 15:29         ` Ard Biesheuvel
2019-12-22 21:12           ` Arvind Sankar
2019-12-22 21:25             ` Ard Biesheuvel
2019-12-23 11:49       ` Hans de Goede
2019-12-23 12:00         ` Ard Biesheuvel
2019-12-18 17:01 ` [PATCH v2 11/21] efi/libstub: get rid of 'sys_table_arg' macro parameter Ard Biesheuvel
2019-12-18 17:01 ` [PATCH v2 12/21] efi/libstub: unify the efi_char16_printk implementations Ard Biesheuvel
2019-12-18 17:01 ` [PATCH v2 13/21] efi/libstub/x86: drop __efi_early() export of efi_config struct Ard Biesheuvel
2019-12-24 19:34   ` Hans de Goede
2019-12-25 14:42     ` Ard Biesheuvel
2019-12-27 22:44       ` Hans de Goede
2019-12-27 22:51         ` Ard Biesheuvel
2019-12-31 23:04   ` Arvind Sankar
2020-01-01 18:13     ` Ard Biesheuvel
2020-01-01 19:08       ` Arvind Sankar
2020-01-02  7:33         ` Ard Biesheuvel
2020-01-02 14:06           ` Arvind Sankar
2020-01-02 15:20             ` Ard Biesheuvel
2020-01-02 15:51               ` Arvind Sankar
2020-01-02 15:58                 ` Ard Biesheuvel
2020-01-02 16:28                   ` Ard Biesheuvel
2020-01-02 16:59                     ` Ard Biesheuvel
2020-01-02 17:26                       ` Arvind Sankar
2020-01-02 17:30                         ` Ard Biesheuvel
2020-01-02 17:41                           ` Arvind Sankar
2020-01-02 17:48                             ` Ard Biesheuvel
2020-01-02 18:10                               ` Arvind Sankar
2020-01-02 18:38                                 ` Ard Biesheuvel
2020-01-03 14:16                                   ` Arvind Sankar
2020-01-03 14:23                                     ` Ard Biesheuvel
2020-01-02 18:38                               ` Arvind Sankar
2020-01-02 16:59                     ` Arvind Sankar
2020-01-02 17:03                       ` Ard Biesheuvel
2020-01-02 17:21                         ` Arvind Sankar
2019-12-18 17:01 ` [PATCH v2 14/21] efi/libstub: drop sys_table_arg from printk routines Ard Biesheuvel
2019-12-18 17:01 ` [PATCH v2 15/21] efi/libstub: remove 'sys_table_arg' from all function prototypes Ard Biesheuvel
2019-12-18 17:01 ` [PATCH v2 16/21] efi/libstub: drop protocol argument from efi_call_proto() macro Ard Biesheuvel
2019-12-18 17:01 ` [PATCH v2 17/21] efi/libstub: drop 'table' argument from efi_table_attr() macro Ard Biesheuvel
2019-12-18 17:01 ` [PATCH v2 18/21] efi/libstub: use 'func' not 'f' as macro parameter Ard Biesheuvel
2019-12-31 16:51   ` Arvind Sankar
2019-12-31 17:06     ` Ard Biesheuvel
2019-12-31 17:36       ` Arvind Sankar
2019-12-18 17:01 ` [PATCH v2 19/21] efi/libstub: tidy up types and names of global cmdline variables Ard Biesheuvel
2019-12-18 17:01 ` [PATCH v2 20/21] efi/libstub: import type definitions for creating and signalling events Ard Biesheuvel
2019-12-18 17:01 ` [PATCH v2 21/21] efi: Allow disabling PCI busmastering on bridges during boot Ard Biesheuvel
2019-12-19  2:50   ` Andy Lutomirski
2019-12-19 13:17     ` Ard Biesheuvel
2019-12-19 20:04       ` Matthew Garrett
2019-12-19 20:04   ` Matthew Garrett
2019-12-20  7:06     ` Ard Biesheuvel
2019-12-20  7:17       ` Andy Lutomirski
2019-12-20  8:11         ` Ard Biesheuvel
2019-12-20 19:41           ` Arvind Sankar
2020-01-02 14:46             ` Laszlo Ersek
2020-01-02 15:40               ` Ard Biesheuvel
2019-12-20 20:43       ` Matthew Garrett
2019-12-21 16:44         ` Ard Biesheuvel
2019-12-21 21:24           ` Matthew Garrett
2019-12-21 22:54             ` Arvind Sankar
2019-12-23 14:02               ` Ard Biesheuvel
2019-12-23 15:46                 ` Arvind Sankar
2019-12-23 15:58                   ` Ard Biesheuvel [this message]
2019-12-23 16:12                     ` Arvind Sankar
2019-12-23 20:57                   ` Matthew Garrett
2020-02-06 14:30   ` Hans de Goede
2020-02-06 14:35     ` Ard Biesheuvel
2020-03-04 10:38       ` Hans de Goede
2020-03-04 18:26         ` Ard Biesheuvel
2020-03-04 18:49           ` Hans de Goede
2020-03-04 21:59             ` Ard Biesheuvel
2019-12-19 11:12 ` [PATCH v2 00/21] efi/x86: confine type unsafe casting to mixed mode Hans de Goede
2019-12-19 13:22   ` Ard Biesheuvel

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