diff mbox series

[v2] doc: describe UEFI measured boot

Message ID 20240614121404.16952-1-ilias.apalodimas@linaro.org
State Superseded
Headers show
Series [v2] doc: describe UEFI measured boot | expand

Commit Message

Ilias Apalodimas June 14, 2024, 12:14 p.m. UTC
We currently only describe the process to enable measured boot using
bootm. Describe the UEFI requirements as well which predate bootm.

Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
---
Changes since v1:
- fixed remarks from Heinrich on titling and DTB measured PCR
 doc/usage/measured_boot.rst | 28 ++++++++++++++++++++++++----
 1 file changed, 24 insertions(+), 4 deletions(-)

--
2.45.1

Comments

Heinrich Schuchardt June 14, 2024, 12:35 p.m. UTC | #1
On 14.06.24 14:14, Ilias Apalodimas wrote:
> We currently only describe the process to enable measured boot using
> bootm. Describe the UEFI requirements as well which predate bootm.
>
> Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
> ---
> Changes since v1:
> - fixed remarks from Heinrich on titling and DTB measured PCR
>   doc/usage/measured_boot.rst | 28 ++++++++++++++++++++++++----
>   1 file changed, 24 insertions(+), 4 deletions(-)
>
> diff --git a/doc/usage/measured_boot.rst b/doc/usage/measured_boot.rst
> index 9691904a9d8a..b5f7b05aeb02 100644
> --- a/doc/usage/measured_boot.rst
> +++ b/doc/usage/measured_boot.rst
> @@ -7,19 +7,39 @@ U-Boot can perform a measured boot, the process of hashing various components
>   of the boot process, extending the results in the TPM and logging the
>   component's measurement in memory for the operating system to consume.
>
> +The functionality is available when booting via the EFI subsystem or 'bootm'
> +command.
> +
> +UEFI measured boot
> +------------------
> +The EFI subsystem implements the `EFI TCG protocol
> +<https://trustedcomputinggroup.org/resource/tcg-efi-protocol-specification/>`_
> +and the `TCG PC Client Specific Platform Firmware Profile Specification
> +<https://trustedcomputinggroup.org/resource/pc-client-specific-platform-firmware-profile-specification/>`_
> +which defines the binaries to be measured and the corresponding PCRs to be used.
> +
> +Requirements
> +~~~~~~~~~~~~
> +* A hardware TPM 2.0 supported by an enabled U-Boot driver
> +* CONFIG_EFI_TCG2_PROTOCOL=y
> +* CONFIG_EFI_TCG2_PROTOCOL_EVENTLOG_SIZE=y
> +* optional CONFIG_EFI_TCG2_PROTOCOL_MEASURE_DTB=y will measure the loaded DTB in PCR 1
> +
> +Measured legacy boot with bootm command
> +----------------------------------------

nits:
The length of the underline should match.

All of bootm, booti, and bootz invoke bootm_run_states() which calls
bootm_measure():

   Measured legacy boot
   --------------------

   The commands booti, bootm, and bootz can be used for measured boot
   using the legacy entry point of the Linux kernel.

Otherwise looks good to me.

Best regards

Heinrich

>   By default, U-Boot will measure the operating system (linux) image, the
>   initrd image, and the "bootargs" environment variable. By enabling
> -CONFIG_MEASURE_DEVICETREE, U-Boot will also measure the devicetree image.
> +CONFIG_MEASURE_DEVICETREE, U-Boot will also measure the devicetree image in PCR1.
>
>   The operating system typically would verify that the hashes found in the
>   TPM PCRs match the contents of the event log. This can further be checked
>   against the hash results of previous boots.
>
>   Requirements
> -------------
> +~~~~~~~~~~~~
>
> -* A hardware TPM 2.0 supported by the U-Boot drivers
> -* CONFIG_TPM=y
> +* A hardware TPM 2.0 supported by an enabled U-Boot driver
> +* CONFIG_TPMv2=y
>   * CONFIG_MEASURED_BOOT=y
>   * Device-tree configuration of the TPM device to specify the memory area
>     for event logging. The TPM device node must either contain a phandle to
> --
> 2.45.1
>
Ilias Apalodimas June 14, 2024, 12:50 p.m. UTC | #2
On Fri, 14 Jun 2024 at 15:40, Heinrich Schuchardt <xypron.glpk@gmx.de> wrote:
>
> On 14.06.24 14:14, Ilias Apalodimas wrote:
> > We currently only describe the process to enable measured boot using
> > bootm. Describe the UEFI requirements as well which predate bootm.
> >
> > Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
> > ---
> > Changes since v1:
> > - fixed remarks from Heinrich on titling and DTB measured PCR
> >   doc/usage/measured_boot.rst | 28 ++++++++++++++++++++++++----
> >   1 file changed, 24 insertions(+), 4 deletions(-)
> >
> > diff --git a/doc/usage/measured_boot.rst b/doc/usage/measured_boot.rst
> > index 9691904a9d8a..b5f7b05aeb02 100644
> > --- a/doc/usage/measured_boot.rst
> > +++ b/doc/usage/measured_boot.rst
> > @@ -7,19 +7,39 @@ U-Boot can perform a measured boot, the process of hashing various components
> >   of the boot process, extending the results in the TPM and logging the
> >   component's measurement in memory for the operating system to consume.
> >
> > +The functionality is available when booting via the EFI subsystem or 'bootm'
> > +command.
> > +
> > +UEFI measured boot
> > +------------------
> > +The EFI subsystem implements the `EFI TCG protocol
> > +<https://trustedcomputinggroup.org/resource/tcg-efi-protocol-specification/>`_
> > +and the `TCG PC Client Specific Platform Firmware Profile Specification
> > +<https://trustedcomputinggroup.org/resource/pc-client-specific-platform-firmware-profile-specification/>`_
> > +which defines the binaries to be measured and the corresponding PCRs to be used.
> > +
> > +Requirements
> > +~~~~~~~~~~~~
> > +* A hardware TPM 2.0 supported by an enabled U-Boot driver
> > +* CONFIG_EFI_TCG2_PROTOCOL=y
> > +* CONFIG_EFI_TCG2_PROTOCOL_EVENTLOG_SIZE=y
> > +* optional CONFIG_EFI_TCG2_PROTOCOL_MEASURE_DTB=y will measure the loaded DTB in PCR 1
> > +
> > +Measured legacy boot with bootm command
> > +----------------------------------------
>
> nits:
> The length of the underline should match.
>
> All of bootm, booti, and bootz invoke bootm_run_states() which calls
> bootm_measure():
>
>    Measured legacy boot
>    --------------------
>
>    The commands booti, bootm, and bootz can be used for measured boot
>    using the legacy entry point of the Linux kernel.
>
> Otherwise looks good to me.

Thanks Heinrich, I'll send a v3

Cheers
/Ilias
>
> Best regards
>
> Heinrich
>
> >   By default, U-Boot will measure the operating system (linux) image, the
> >   initrd image, and the "bootargs" environment variable. By enabling
> > -CONFIG_MEASURE_DEVICETREE, U-Boot will also measure the devicetree image.
> > +CONFIG_MEASURE_DEVICETREE, U-Boot will also measure the devicetree image in PCR1.
> >
> >   The operating system typically would verify that the hashes found in the
> >   TPM PCRs match the contents of the event log. This can further be checked
> >   against the hash results of previous boots.
> >
> >   Requirements
> > -------------
> > +~~~~~~~~~~~~
> >
> > -* A hardware TPM 2.0 supported by the U-Boot drivers
> > -* CONFIG_TPM=y
> > +* A hardware TPM 2.0 supported by an enabled U-Boot driver
> > +* CONFIG_TPMv2=y
> >   * CONFIG_MEASURED_BOOT=y
> >   * Device-tree configuration of the TPM device to specify the memory area
> >     for event logging. The TPM device node must either contain a phandle to
> > --
> > 2.45.1
> >
>
diff mbox series

Patch

diff --git a/doc/usage/measured_boot.rst b/doc/usage/measured_boot.rst
index 9691904a9d8a..b5f7b05aeb02 100644
--- a/doc/usage/measured_boot.rst
+++ b/doc/usage/measured_boot.rst
@@ -7,19 +7,39 @@  U-Boot can perform a measured boot, the process of hashing various components
 of the boot process, extending the results in the TPM and logging the
 component's measurement in memory for the operating system to consume.

+The functionality is available when booting via the EFI subsystem or 'bootm'
+command.
+
+UEFI measured boot
+------------------
+The EFI subsystem implements the `EFI TCG protocol
+<https://trustedcomputinggroup.org/resource/tcg-efi-protocol-specification/>`_
+and the `TCG PC Client Specific Platform Firmware Profile Specification
+<https://trustedcomputinggroup.org/resource/pc-client-specific-platform-firmware-profile-specification/>`_
+which defines the binaries to be measured and the corresponding PCRs to be used.
+
+Requirements
+~~~~~~~~~~~~
+* A hardware TPM 2.0 supported by an enabled U-Boot driver
+* CONFIG_EFI_TCG2_PROTOCOL=y
+* CONFIG_EFI_TCG2_PROTOCOL_EVENTLOG_SIZE=y
+* optional CONFIG_EFI_TCG2_PROTOCOL_MEASURE_DTB=y will measure the loaded DTB in PCR 1
+
+Measured legacy boot with bootm command
+----------------------------------------
 By default, U-Boot will measure the operating system (linux) image, the
 initrd image, and the "bootargs" environment variable. By enabling
-CONFIG_MEASURE_DEVICETREE, U-Boot will also measure the devicetree image.
+CONFIG_MEASURE_DEVICETREE, U-Boot will also measure the devicetree image in PCR1.

 The operating system typically would verify that the hashes found in the
 TPM PCRs match the contents of the event log. This can further be checked
 against the hash results of previous boots.

 Requirements
-------------
+~~~~~~~~~~~~

-* A hardware TPM 2.0 supported by the U-Boot drivers
-* CONFIG_TPM=y
+* A hardware TPM 2.0 supported by an enabled U-Boot driver
+* CONFIG_TPMv2=y
 * CONFIG_MEASURED_BOOT=y
 * Device-tree configuration of the TPM device to specify the memory area
   for event logging. The TPM device node must either contain a phandle to