Re: [PATCH v2 3/3] tpm: parse TPM event logs based on EFI table

[Jarkko Sakkinen]

On Mon, Sep 11, 2017 at 12:00:22PM +0200, Thiebaud Weksteen wrote:
> If we are not able to retrieve the TPM event logs from the ACPI table,
> check the EFI configuration table (Linux-specific GUID).
> 
> The format version of the log may be returned by the function. If not
> specified (by previous implementation: tpm_acpi and tpm_of), we default
> to the version of the chip (previous behaviour).
> 
> Signed-off-by: Thiebaud Weksteen <tweek@xxxxxxxxxx>

You saw my comment about file naming. I.e. tpm_eventlog_efi.c would be
a more senseful name.

> ---
>  drivers/char/tpm/Makefile        |  2 +-
>  drivers/char/tpm/tpm.h           |  8 +++++
>  drivers/char/tpm/tpm1_eventlog.c | 15 +++++++--
>  drivers/char/tpm/tpm_efi.c       | 66 ++++++++++++++++++++++++++++++++++++++++
>  drivers/firmware/efi/efi.c       |  2 ++
>  include/linux/efi.h              |  1 +
>  6 files changed, 90 insertions(+), 4 deletions(-)
>  create mode 100644 drivers/char/tpm/tpm_efi.c
> 
> diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile
> index 23681f01f95a..74182a63eef2 100644
> --- a/drivers/char/tpm/Makefile
> +++ b/drivers/char/tpm/Makefile
> @@ -4,7 +4,7 @@
>  obj-$(CONFIG_TCG_TPM) += tpm.o
>  tpm-y := tpm-interface.o tpm-dev.o tpm-sysfs.o tpm-chip.o tpm2-cmd.o \
>  	 tpm-dev-common.o tpmrm-dev.o tpm1_eventlog.o tpm2_eventlog.o \
> -         tpm2-space.o
> +         tpm2-space.o tpm_efi.o
>  tpm-$(CONFIG_ACPI) += tpm_ppi.o tpm_acpi.o
>  tpm-$(CONFIG_OF) += tpm_of.o
>  obj-$(CONFIG_TCG_TIS_CORE) += tpm_tis_core.o
> diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
> index 46caccf6fd1a..1bd97e01df50 100644
> --- a/drivers/char/tpm/tpm.h
> +++ b/drivers/char/tpm/tpm.h
> @@ -597,6 +597,14 @@ static inline int tpm_read_log_of(struct tpm_chip *chip)
>  	return -ENODEV;
>  }
>  #endif
> +#if defined(CONFIG_EFI)
> +int tpm_read_log_efi(struct tpm_chip *chip);
> +#else
> +static inline int tpm_read_log_efi(struct tpm_chip *chip)
> +{
> +	return -ENODEV;
> +}
> +#endif
>  
>  int tpm_bios_log_setup(struct tpm_chip *chip);
>  void tpm_bios_log_teardown(struct tpm_chip *chip);
> diff --git a/drivers/char/tpm/tpm1_eventlog.c b/drivers/char/tpm/tpm1_eventlog.c
> index d6f70f365443..7e25e6bff6ce 100644
> --- a/drivers/char/tpm/tpm1_eventlog.c
> +++ b/drivers/char/tpm/tpm1_eventlog.c
> @@ -21,6 +21,7 @@
>   */
>  
>  #include <linux/seq_file.h>
> +#include <linux/efi.h>
>  #include <linux/fs.h>
>  #include <linux/security.h>
>  #include <linux/module.h>
> @@ -371,6 +372,10 @@ static int tpm_read_log(struct tpm_chip *chip)
>  	if (rc != -ENODEV)
>  		return rc;
>  
> +	rc = tpm_read_log_efi(chip);
> +	if (rc != -ENODEV)
> +		return rc;
> +
>  	return tpm_read_log_of(chip);
>  }
>  
> @@ -388,11 +393,13 @@ int tpm_bios_log_setup(struct tpm_chip *chip)
>  {
>  	const char *name = dev_name(&chip->dev);
>  	unsigned int cnt;
> -	int rc = 0;
> +	int rc = 0, log_version;

A tid bit, one declaration per line.

> +
>  
>  	rc = tpm_read_log(chip);
> -	if (rc)
> +	if (rc < 0)
>  		return rc;
> +	log_version = rc;
>  
>  	cnt = 0;
>  	chip->bios_dir[cnt] = securityfs_create_dir(name, NULL);
> @@ -404,7 +411,9 @@ int tpm_bios_log_setup(struct tpm_chip *chip)
>  	cnt++;
>  
>  	chip->bin_log_seqops.chip = chip;
> -	if (chip->flags & TPM_CHIP_FLAG_TPM2)
> +
> +	if (log_version == EFI_TCG2_EVENT_LOG_FORMAT_TCG_2 ||
> +	    (!log_version && (chip->flags & TPM_CHIP_FLAG_TPM2)))
>  		chip->bin_log_seqops.seqops =
>  			&tpm2_binary_b_measurements_seqops;
>  	else
> diff --git a/drivers/char/tpm/tpm_efi.c b/drivers/char/tpm/tpm_efi.c
> new file mode 100644
> index 000000000000..c8247fc45bb0
> --- /dev/null
> +++ b/drivers/char/tpm/tpm_efi.c
> @@ -0,0 +1,66 @@
> +/*
> + * Copyright (C) 2017 Google
> + *
> + * Authors:
> + *      Thiebaud Weksteen <tweek@xxxxxxxxxx>
> + *
> + * This program 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
> + * 2 of the License, or (at your option) any later version.
> + *
> + */
> +
> +#include <linux/efi.h>
> +#include <linux/tpm_eventlog.h>
> +
> +#include "tpm.h"
> +
> +/* read binary bios log from EFI configuration table */
> +int tpm_read_log_efi(struct tpm_chip *chip)
> +{
> +
> +	struct linux_efi_tpm_eventlog *log_tbl;
> +	struct tpm_bios_log *log;
> +	u32 log_size;
> +	u8 tpm_log_version;
> +
> +	if (!(chip->flags & TPM_CHIP_FLAG_TPM2))
> +		return -ENODEV;
> +
> +	if (efi.tpm_log == EFI_INVALID_TABLE_ADDR)
> +		return -ENODEV;
> +
> +	log = &chip->log;
> +
> +	log_tbl = memremap(efi.tpm_log, sizeof(*log_tbl), MEMREMAP_WB);
> +	if (!log_tbl) {
> +		pr_err("Could not map UEFI TPM log table !\n");
> +		return -ENOMEM;
> +	}
> +
> +	log_size = log_tbl->size;
> +	iounmap(log_tbl);
> +
> +	log_tbl = memremap(efi.tpm_log, sizeof(*log_tbl) + log_size,
> +			   MEMREMAP_WB);
> +	if (!log_tbl) {
> +		pr_err("Could not map UEFI TPM log table payload!\n");
> +		return -ENOMEM;
> +	}
> +
> +	/* malloc EventLog space */
> +	log->bios_event_log = kmalloc(log_size, GFP_KERNEL);
> +	if (!log->bios_event_log)
> +		goto err_iounmap;
> +	memcpy(log->bios_event_log, log_tbl->log, log_size);
> +	log->bios_event_log_end = log->bios_event_log + log_size;
> +
> +	tpm_log_version = log_tbl->version;
> +	iounmap(log_tbl);
> +	return tpm_log_version;
> +
> +err_iounmap:
> +	iounmap(log_tbl);
> +	return -ENOMEM;
> +}
> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> index 03fbaf8eb248..0308acfaaf76 100644
> --- a/drivers/firmware/efi/efi.c
> +++ b/drivers/firmware/efi/efi.c
> @@ -52,6 +52,7 @@ struct efi __read_mostly efi = {
>  	.properties_table	= EFI_INVALID_TABLE_ADDR,
>  	.mem_attr_table		= EFI_INVALID_TABLE_ADDR,
>  	.rng_seed		= EFI_INVALID_TABLE_ADDR,
> +	.tpm_log		= EFI_INVALID_TABLE_ADDR
>  };
>  EXPORT_SYMBOL(efi);
>  
> @@ -444,6 +445,7 @@ static __initdata efi_config_table_type_t common_tables[] = {
>  	{EFI_PROPERTIES_TABLE_GUID, "PROP", &efi.properties_table},
>  	{EFI_MEMORY_ATTRIBUTES_TABLE_GUID, "MEMATTR", &efi.mem_attr_table},
>  	{LINUX_EFI_RANDOM_SEED_TABLE_GUID, "RNG", &efi.rng_seed},
> +	{LINUX_EFI_TPM_EVENT_LOG_GUID, "TPMEventLog", &efi.tpm_log},
>  	{NULL_GUID, NULL, NULL},
>  };
>  
> diff --git a/include/linux/efi.h b/include/linux/efi.h
> index e671ea9a462e..ab78950e6911 100644
> --- a/include/linux/efi.h
> +++ b/include/linux/efi.h
> @@ -943,6 +943,7 @@ extern struct efi {
>  	unsigned long properties_table;	/* properties table */
>  	unsigned long mem_attr_table;	/* memory attributes table */
>  	unsigned long rng_seed;		/* UEFI firmware random seed */
> +	unsigned long tpm_log;		/* TPM2 Event Log table */
>  	efi_get_time_t *get_time;
>  	efi_set_time_t *set_time;
>  	efi_get_wakeup_time_t *get_wakeup_time;
> -- 
> 2.14.1.581.gf28d330327-goog
> 

I would not put efi changes to the same commit.

I did not have too detailed look but code changes look nice and
clean overally. I'll give this more detailed review once it is
sent to linux-integrity@xxxxxxxxxxxxxxx and CC'd to
linux-security-module@xxxxxxxxxxxxxxxx

/Jarkko