On Thu, Dec 01, 2022 at 04:12:01PM -0500, Stefan Berger wrote:
> Add support for trusted boot using a vTPM 2.0 on the IBM IEEE1275
> PowerPC platform. With this patch grub now measures text and binary data
> into the TPM's PCRs 8 and 9 in the same way as the x86_64 platform
> does.
>
> This patch requires Daniel Axtens's patches for claiming more memory.
>
> For vTPM support to work on PowerVM, system driver levels 1010.30
> or 1020.00 are required.
>
> Note: Previous versions of firmware levels with the 2hash-ext-log
> API call have a bug that, once this API call is invoked, has the
> effect of disabling the vTPM driver under Linux causing an error
> message to be displayed in the Linux kernel log. Those users will
> have to update their machines to the firmware levels mentioned
> above.
>
> Cc: Eric Snowberg <eric.snowb...@oracle.com>
> Signed-off-by: Stefan Berger <stef...@linux.ibm.com>
> Signed-off-by: Daniel Axtens <d...@axtens.net>
> ---
> docs/grub.texi | 3 +-
> grub-core/Makefile.core.def | 7 ++
> grub-core/commands/ieee1275/ibmvtpm.c | 151 ++++++++++++++++++++++++++
> include/grub/ieee1275/ieee1275.h | 3 +
> 4 files changed, 163 insertions(+), 1 deletion(-)
> create mode 100644 grub-core/commands/ieee1275/ibmvtpm.c
>
> diff --git a/docs/grub.texi b/docs/grub.texi
> index 50c811a88..580f2a995 100644
> --- a/docs/grub.texi
> +++ b/docs/grub.texi
> @@ -6413,7 +6413,8 @@ tpm module is loaded. As such it is recommended that
> the tpm module be built
> into @file{core.img} in order to avoid a potential gap in measurement between
> @file{core.img} being loaded and the tpm module being loaded.
>
> -Measured boot is currently only supported on EFI platforms.
> +Measured boot is currently only supported on EFI and IBM IEEE1275 PowerPC
> +platforms.
>
> @node Lockdown
> @section Lockdown when booting on a secure setup
> diff --git a/grub-core/Makefile.core.def b/grub-core/Makefile.core.def
> index 0ec95997d..ef6964b91 100644
> --- a/grub-core/Makefile.core.def
> +++ b/grub-core/Makefile.core.def
> @@ -1133,6 +1133,13 @@ module = {
> enable = powerpc_ieee1275;
> };
>
> +module = {
> + name = tpm;
> + common = commands/tpm.c;
> + ieee1275 = commands/ieee1275/ibmvtpm.c;
> + enable = powerpc_ieee1275;
> +};
> +
> module = {
> name = terminal;
> common = commands/terminal.c;
> diff --git a/grub-core/commands/ieee1275/ibmvtpm.c
> b/grub-core/commands/ieee1275/ibmvtpm.c
> new file mode 100644
> index 000000000..78e002c47
> --- /dev/null
> +++ b/grub-core/commands/ieee1275/ibmvtpm.c
> @@ -0,0 +1,151 @@
> +/*
> + * GRUB -- GRand Unified Bootloader
> + * Copyright (C) 2022 Free Software Foundation, Inc.
> + * Copyright (C) 2022 IBM Corporation
> + *
> + * GRUB is free software: you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation, either version 3 of the License, or
> + * (at your option) any later version.
> + *
> + * GRUB is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with GRUB. If not, see <http://www.gnu.org/licenses/>.
> + *
> + * IBM vTPM support code.
> + */
> +
> +#include <grub/err.h>
> +#include <grub/types.h>
> +#include <grub/tpm.h>
> +#include <grub/ieee1275/ieee1275.h>
> +#include <grub/mm.h>
> +#include <grub/misc.h>
> +
> +static grub_ieee1275_ihandle_t tpm_ihandle;
> +static grub_uint8_t tpm_version;
> +
> +#define IEEE1275_IHANDLE_INVALID ((grub_ieee1275_ihandle_t) 0)
> +
> +static void
> +tpm_get_tpm_version (void)
> +{
> + grub_ieee1275_phandle_t vtpm;
> + char buffer[20];
> +
> + if (!grub_ieee1275_finddevice ("/vdevice/vtpm", &vtpm) &&
> + !grub_ieee1275_get_property (vtpm, "compatible", buffer,
> + sizeof (buffer), NULL) &&
> + !grub_strcmp (buffer, "IBM,vtpm20"))
> + tpm_version = 2;
> +}
> +
> +static grub_err_t
> +tpm_init (void)
> +{
> + static int init_success = 0;
> +
> + if (!init_success)
> + {
> + if (grub_ieee1275_open ("/vdevice/vtpm", &tpm_ihandle) < 0)
> + {
> + tpm_ihandle = IEEE1275_IHANDLE_INVALID;
> + return GRUB_ERR_UNKNOWN_DEVICE;
> + }
> +
> + init_success = 1;
> +
> + tpm_get_tpm_version ();
> + }
> +
> + return GRUB_ERR_NONE;
> +}
> +
> +static int
> +ibmvtpm_2hash_ext_log (grub_uint8_t pcrindex,
> + grub_uint32_t eventtype,
> + const char *description,
> + grub_size_t description_size,
> + void *buf, grub_size_t size)
> +{
> + struct tpm_2hash_ext_log
> + {
> + struct grub_ieee1275_common_hdr common;
> + grub_ieee1275_cell_t method;
> + grub_ieee1275_cell_t ihandle;
> + grub_ieee1275_cell_t size;
> + grub_ieee1275_cell_t buf;
> + grub_ieee1275_cell_t description_size;
> + grub_ieee1275_cell_t description;
> + grub_ieee1275_cell_t eventtype;
> + grub_ieee1275_cell_t pcrindex;
> + grub_ieee1275_cell_t catch_result;
> + grub_ieee1275_cell_t rc;
> + };
> + struct tpm_2hash_ext_log args;
> +
> + INIT_IEEE1275_COMMON (&args.common, "call-method", 8, 2);
> + args.method = (grub_ieee1275_cell_t) "2hash-ext-log";
> + args.ihandle = tpm_ihandle;
> + args.pcrindex = pcrindex;
> + args.eventtype = eventtype;
> + args.description = (grub_ieee1275_cell_t) description;
> + args.description_size = description_size;
> + args.buf = (grub_ieee1275_cell_t) buf;
> + args.size = (grub_ieee1275_cell_t) size;
> +
> + if (IEEE1275_CALL_ENTRY_FN (&args) == -1)
> + return -1;
> +
> + /*
> + * catch_result is set if firmware does not support 2hash-ext-log
> + * rc is GRUB_IEEE1275_CELL_FALSE (0) on failure
> + */
> + if ((args.catch_result) || args.rc == GRUB_IEEE1275_CELL_FALSE)
> + return -1;
> +
> + return 0;
> +}
> +
> +static grub_err_t
> +tpm2_log_event (unsigned char *buf, grub_size_t size, grub_uint8_t pcr,
> + const char *description)
> +{
> + static int error_displayed = 0;
> + int rc;
> +
> + rc = ibmvtpm_2hash_ext_log (pcr, EV_IPL,
> + description, grub_strlen(description) + 1,
> + buf, size);
> + if (rc && !error_displayed)
> + {
> + error_displayed++;
> + return grub_error (GRUB_ERR_BAD_DEVICE,
> + "2HASH-EXT-LOG failed: Firmware is likely too old.\n");
> + }
> +
> + return GRUB_ERR_NONE;
> +}
> +
> +grub_err_t
> +grub_tpm_measure (unsigned char *buf, grub_size_t size, grub_uint8_t pcr,
> + const char *description)
> +{
> + grub_err_t err = tpm_init ();
This should happen on module load. Then code in tpm_init() and here should
be much simpler.
> + /* Absence of a TPM isn't a failure. */
> + if (err != GRUB_ERR_NONE)
> + return GRUB_ERR_NONE;
> +
> + grub_dprintf ("tpm", "log_event, pcr = %d, size = 0x%" PRIxGRUB_SIZE ",
> %s\n",
> + pcr, size, description);
> +
> + if (tpm_version == 2)
> + return tpm2_log_event (buf, size, pcr, description);
> +
> + return GRUB_ERR_NONE;
> +}
Daniel
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