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Date: Wed, 30 Nov 2016 22:29:00 +0530
From: Nayna <nayna@...ux.vnet.ibm.com>
To: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc: tpmdd-devel@...ts.sourceforge.net, peterhuewe@....de,
tpmdd@...horst.net, jgunthorpe@...idianresearch.com,
linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 2/2] tpm: add securityfs support for TPM 2.0 firmware
event log
On 11/26/2016 09:17 PM, Jarkko Sakkinen wrote:
> On Sat, Nov 26, 2016 at 07:45:39AM -0500, Nayna Jain wrote:
>> Unlike the device driver support for TPM 1.2, the TPM 2.0 does
>> not support the securityfs pseudo files for displaying the
>> firmware event log.
>>
>> This patch enables support for providing the TPM 2.0 event log in
>> binary form. TPM 2.0 event log supports a crypto agile format that
>> records multiple digests, which is different from TPM 1.2. This
>> patch enables the tpm_bios_log_setup for TPM 2.0 and adds the
>> event log parser which understand the TPM 2.0 crypto agile format.
>>
>> Signed-off-by: Nayna Jain <nayna@...ux.vnet.ibm.com>
>
> I would not rush with new patch set versions as long as the testing is
> almost completely lacking. I didn't even have time to read the previous
> version properly before this came out.
Sure Jarkko. My apologies for multiple versions. I will wait for
testing, before posting my next version.
>
>> ---
>> drivers/char/tpm/Makefile | 2 +-
>> .../char/tpm/{tpm_eventlog.c => tpm1_eventlog.c} | 35 ++--
>> drivers/char/tpm/tpm2_eventlog.c | 214 +++++++++++++++++++++
>> drivers/char/tpm/tpm_eventlog.h | 70 +++++++
>> 4 files changed, 306 insertions(+), 15 deletions(-)
>> rename drivers/char/tpm/{tpm_eventlog.c => tpm1_eventlog.c} (95%)
>> create mode 100644 drivers/char/tpm/tpm2_eventlog.c
>>
>> diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile
>> index a05b1eb..3d386a8 100644
>> --- a/drivers/char/tpm/Makefile
>> +++ b/drivers/char/tpm/Makefile
>> @@ -3,7 +3,7 @@
>> #
>> obj-$(CONFIG_TCG_TPM) += tpm.o
>> tpm-y := tpm-interface.o tpm-dev.o tpm-sysfs.o tpm-chip.o tpm2-cmd.o \
>> - tpm_eventlog.o
>> + tpm1_eventlog.o tpm2_eventlog.o
>> tpm-$(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_eventlog.c b/drivers/char/tpm/tpm1_eventlog.c
>> similarity index 95%
>> rename from drivers/char/tpm/tpm_eventlog.c
>> rename to drivers/char/tpm/tpm1_eventlog.c
>> index fe7e3fa..e9a092b 100644
>> --- a/drivers/char/tpm/tpm_eventlog.c
>> +++ b/drivers/char/tpm/tpm1_eventlog.c
>> @@ -390,9 +390,6 @@ int tpm_bios_log_setup(struct tpm_chip *chip)
>> unsigned int cnt;
>> int rc;
>>
>> - if (chip->flags & TPM_CHIP_FLAG_TPM2)
>> - return 0;
>> -
>> rc = tpm_read_log(chip);
>> if (rc)
>> return rc;
>> @@ -407,7 +404,13 @@ int tpm_bios_log_setup(struct tpm_chip *chip)
>> cnt++;
>>
>> chip->bin_log_seqops.chip = chip;
>> - chip->bin_log_seqops.seqops = &tpm_binary_b_measurements_seqops;
>> + if (chip->flags & TPM_CHIP_FLAG_TPM2)
>> + chip->bin_log_seqops.seqops =
>> + &tpm2_binary_b_measurements_seqops;
>> + else
>> + chip->bin_log_seqops.seqops =
>> + &tpm_binary_b_measurements_seqops;
>> +
>>
>> chip->bios_dir[cnt] =
>> securityfs_create_file("binary_bios_measurements",
>> @@ -418,17 +421,21 @@ int tpm_bios_log_setup(struct tpm_chip *chip)
>> goto err;
>> cnt++;
>>
>> - chip->ascii_log_seqops.chip = chip;
>> - chip->ascii_log_seqops.seqops = &tpm_ascii_b_measurements_seqops;
>> + if (!(chip->flags & TPM_CHIP_FLAG_TPM2)) {
>>
>> - chip->bios_dir[cnt] =
>> - securityfs_create_file("ascii_bios_measurements",
>> - 0440, chip->bios_dir[0],
>> - (void *)&chip->ascii_log_seqops,
>> - &tpm_bios_measurements_ops);
>> - if (IS_ERR(chip->bios_dir[cnt]))
>> - goto err;
>> - cnt++;
>> + chip->ascii_log_seqops.chip = chip;
>> + chip->ascii_log_seqops.seqops =
>> + &tpm_ascii_b_measurements_seqops;
>> +
>> + chip->bios_dir[cnt] =
>> + securityfs_create_file("ascii_bios_measurements",
>> + 0440, chip->bios_dir[0],
>> + (void *)&chip->ascii_log_seqops,
>> + &tpm_bios_measurements_ops);
>> + if (IS_ERR(chip->bios_dir[cnt]))
>> + goto err;
>> + cnt++;
>> + }
>>
>> return 0;
>>
>> diff --git a/drivers/char/tpm/tpm2_eventlog.c b/drivers/char/tpm/tpm2_eventlog.c
>> new file mode 100644
>> index 0000000..cf9fea0
>> --- /dev/null
>> +++ b/drivers/char/tpm/tpm2_eventlog.c
>> @@ -0,0 +1,214 @@
>> +/*
>> + * Copyright (C) 2016 IBM Corporation
>> + *
>> + * Authors:
>> + * Nayna Jain <nayna@...ux.vnet.ibm.com>
>> + *
>> + * Access to TPM 2.0 event log as written by Firmware.
>> + * It assumes that writer of event log has followed TCG Spec 2.0
>> + * and written the event struct data in little endian. With that,
>> + * it doesn't need any endian conversion for structure content.
>> + *
>> + * 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/seq_file.h>
>> +#include <linux/fs.h>
>> +#include <linux/security.h>
>> +#include <linux/module.h>
>> +#include <linux/slab.h>
>> +
>> +#include "tpm.h"
>> +#include "tpm_eventlog.h"
>> +
>> +static int calc_tpm2_event_size(struct tcg_pcr_event2 *event,
>> + struct tcg_pcr_event *event_header)
>> +{
>> + struct tcg_efi_specid_event *efispecid;
>> + struct tcg_event_field *event_field;
>> + void *marker, *marker_start;
>
> Split to two lines.
Will fix it.
>
>> + int i, j;
>
> Split to two lines.
Sure.
>
>> + u16 halg;
>> + u32 halg_size;
>> + size_t size = 0;
>
> Please do not initialize variables unless you need to initialize them in
> the declaration. It is not a good practice. And in here it is especially
> misleading because you don't initialize anything else. I assumed first
> that there might be a special reason why size is initialized.
>
Sure. Will fix.
>> +
>> + /*
>> + * NOTE: TPM 2.0 supports extend to multiple PCR Banks. This implies
>> + * event log also has multiple digest values, one for each PCR Bank.
>> + * This is called Crypto Agile Log Entry Format.
>> + * TCG EFI Protocol Specification defines the procedure to parse
>> + * the event log. Below code implements this procedure to parse
>> + * correctly the Crypto agile log entry format.
>> + * Example of Crypto Agile Log Digests Format :
>> + * digest_values.count = 2;
>> + * digest_values.digest[0].alg_id = sha1;
>> + * digest_values.digest[0].digest.sha1 = {20 bytes raw data};
>> + * digest_values.digest[1].alg_id = sha256;
>> + * digest_values.digest[1].digest.sha256 = {32 bytes raw data};
>> + * Offset of eventsize is sizeof(count) + sizeof(alg_id) + 20
>> + * + sizeof(alg_id) + 32;
>> + *
>
> The bellow code does not implement anything. I woud just keep the first
> paragraph in this comment.
Ok. Thanks for looking on this. I will keep only first paragraph.
>
>> + * Since, offset of event_size can vary based on digests count, offset
>> + * has to be calculated at run time. void *marker is used to traverse
>> + * the dynamic structure and calculate the offset of event_size.
>> + */
>> +
>> + marker = event;
>> + marker_start = marker;
>> + marker = marker + sizeof(event->pcr_idx) + sizeof(event->event_type)
>> + + sizeof(event->digests.count);
>> +
>> + efispecid = (struct tcg_efi_specid_event *) event_header->event;
>> +
>> + for (i = 0; (i < event->digests.count) && (i < HASH_COUNT); i++) {
>> + halg_size = sizeof(event->digests.digests[i].alg_id);
>> + memcpy(&halg, marker, halg_size);
>> + marker = marker + halg_size;
>> + for (j = 0; (j < efispecid->num_algs); j++) {
>> + if (halg == efispecid->digest_sizes[j].alg_id) {
>> + marker = marker +
>> + efispecid->digest_sizes[j].digest_size;
>> + break;
>> + }
>> + }
>> + }
>> +
>> + event_field = (struct tcg_event_field *) marker;
>> + marker = marker + sizeof(event_field->event_size)
>> + + event_field->event_size;
>> + size = marker - marker_start;
>> +
>> + if ((event->event_type == 0) && (event_field->event_size == 0))
>> + return 0;
>> +
>> + return size;
>> +}
>> +
>> +static void *tpm2_bios_measurements_start(struct seq_file *m, loff_t *pos)
>> +{
>> + struct tpm_chip *chip = m->private;
>> + struct tpm_bios_log *log = &chip->log;
>> + void *addr = log->bios_event_log;
>> + void *limit = log->bios_event_log_end;
>> + struct tcg_pcr_event *event_header;
>> + struct tcg_pcr_event2 *event;
>> + int i;
>> + size_t size = 0;
>
> Again.
Will fix.
>
>> +
>> + event_header = addr;
>> +
>> + size = sizeof(struct tcg_pcr_event) - sizeof(event_header->event)
>> + + event_header->event_size;
>> +
>> +
>
> Why two newline characters?
Will fix.
>
>> + if (*pos == 0) {
>> + if (addr + size < limit) {
>> + if ((event_header->event_type == 0) &&
>> + (event_header->event_size == 0))
>> + return NULL;
>> + return SEQ_START_TOKEN;
>> + }
>> + }
>> +
>> + if (*pos > 0) {
>> + addr += size;
>> + event = addr;
>> + size = calc_tpm2_event_size(event, event_header);
>> + if ((addr + size >= limit) || (size == 0))
>> + return NULL;
>> + }
>> +
>> + /* read over *pos measurements */
>
> What does this comment tell that the code below does not tell? And in
> addition to that it is incorrect. You are reading over *pos - 1
> measurements, not *pos measurements.
Hmm.. Ok.. looks now like probably not needed.
>
>> + for (i = 0; i < (*pos - 1); i++) {
>> + event = addr;
>> + size = calc_tpm2_event_size(event, event_header);
>> +
>> + if ((addr + size >= limit) || (size == 0))
>> + return NULL;
>> + addr += size;
>> + }
>> +
>> + return addr;
>> +}
>> +
>> +static void *tpm2_bios_measurements_next(struct seq_file *m, void *v,
>> + loff_t *pos)
>> +{
>> + struct tcg_pcr_event *event_header;
>> + struct tcg_pcr_event2 *event;
>> + struct tpm_chip *chip = m->private;
>> + struct tpm_bios_log *log = &chip->log;
>> + void *limit = log->bios_event_log_end;
>> + void *marker;
>> + size_t event_size = 0;
>
> Again.
Will fix.
>
>> +
>> + event_header = log->bios_event_log;
>> +
>> + if (v == SEQ_START_TOKEN) {
>> + event_size = sizeof(struct tcg_pcr_event)
>> + - sizeof(event_header->event)
>> + + event_header->event_size;
>> + marker = event_header;
>> + } else {
>> + event = v;
>> + event_size = calc_tpm2_event_size(event, event_header);
>> + if (event_size == 0)
>> + return NULL;
>> + marker = event;
>> + }
>> +
>> + marker = marker + event_size;
>> + if (marker >= limit)
>> + return NULL;
>> + v = marker;
>> + event = v;
>> +
>> + event_size = calc_tpm2_event_size(event, event_header);
>> + if (((v + event_size) >= limit) || (event_size == 0))
>> + return NULL;
>> +
>> + (*pos)++;
>> + return v;
>> +}
>> +
>> +static void tpm2_bios_measurements_stop(struct seq_file *m, void *v)
>> +{
>> +}
>> +
>> +static int tpm2_binary_bios_measurements_show(struct seq_file *m, void *v)
>> +{
>> + struct tpm_chip *chip = m->private;
>> + struct tpm_bios_log *log = &chip->log;
>> + struct tcg_pcr_event *event_header = log->bios_event_log;
>> + struct tcg_pcr_event2 *event = v;
>> + void *temp_ptr;
>> + size_t size = 0;
>> +
>> + if (v == SEQ_START_TOKEN) {
>> + size = sizeof(struct tcg_pcr_event)
>> + - sizeof(event_header->event)
>> + + event_header->event_size;
>> +
>> + temp_ptr = event_header;
>> +
>> + if (size > 0)
>> + seq_write(m, temp_ptr, size);
>> + } else {
>> + size = calc_tpm2_event_size(event, event_header);
>> + temp_ptr = event;
>> + if (size > 0)
>> + seq_write(m, temp_ptr, size);
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +const struct seq_operations tpm2_binary_b_measurements_seqops = {
>> + .start = tpm2_bios_measurements_start,
>> + .next = tpm2_bios_measurements_next,
>> + .stop = tpm2_bios_measurements_stop,
>> + .show = tpm2_binary_bios_measurements_show,
>> +};
>> diff --git a/drivers/char/tpm/tpm_eventlog.h b/drivers/char/tpm/tpm_eventlog.h
>> index 1660d74..7e33b90 100644
>> --- a/drivers/char/tpm/tpm_eventlog.h
>> +++ b/drivers/char/tpm/tpm_eventlog.h
>> @@ -5,6 +5,9 @@
>> #define TCG_EVENT_NAME_LEN_MAX 255
>> #define MAX_TEXT_EVENT 1000 /* Max event string length */
>> #define ACPI_TCPA_SIG "TCPA" /* 0x41504354 /'TCPA' */
>> +#define HASH_COUNT 3
>> +#define MAX_TPM_LOG_MSG 128
>> +#define MAX_DIGEST_SIZE 64
>
> Where have been the values for these constants derived? You should
> anyway prefix them with TPM_.
HASH_COUNT is to represent multiple active banks at a time, where SHA1
and SHA256 are the ones, I kept it 3 with assumption of SHA384/SHA512.
And with that, I kept MAX_DIGEST_SIZE as 64.
MAX_TPM_LOG_MSG was an assumption by me. I think TCG Spec says max value
can be 1MB.
I would actually like to know the views on this.
>
>> #ifdef CONFIG_PPC64
>> #define do_endian_conversion(x) be32_to_cpu(x)
>> @@ -73,6 +76,73 @@ enum tcpa_pc_event_ids {
>> HOST_TABLE_OF_DEVICES,
>> };
>>
>> +/*
>> + * All the structures related to TPM 2.0 Event Log are taken from TCG EFIi
>> + * Protocol * Specification, Family "2.0". Document is available on link
>> + * http://www.trustedcomputinggroup.org/tcg-efi-protocol-specification/
>> + * Information is also available on TCG PC Client Platform Firmware Profile
>> + * Specification, Family "2.0"
>> + * Detailed digest structures for TPM 2.0 are defined in document
>> + * Trusted Platform Module Library Part 2: Structures, Family "2.0".
>> + */
>> +
>> +/* TPM 2.0 Event log header algorithm spec. */
>> +struct tcg_efi_specid_event_algs {
>> + u16 alg_id;
>> + u16 digest_size;
>> +} __packed;
>> +
>> +/* TPM 2.0 Event log header data. */
>> +struct tcg_efi_specid_event {
>> + u8 signature[16];
>> + u32 platform_class;
>> + u8 spec_version_minor;
>> + u8 spec_version_major;
>> + u8 spec_errata;
>> + u8 uintnsize;
>> + u32 num_algs;
>> + struct tcg_efi_specid_event_algs digest_sizes[HASH_COUNT];
>> + u8 vendor_info_size;
>> + u8 vendor_info[0];
>> +} __packed;
>> +
>> +/* TPM 2.0 Event Log Header. */
>> +struct tcg_pcr_event {
>> + u32 pcr_idx;
>> + u32 event_type;
>> + u8 digest[20];
>> + u32 event_size;
>> + u8 event[MAX_TPM_LOG_MSG];
>> +} __packed;
>> +
>> +/* TPM 2.0 Crypto agile algorithm and respective digest. */
>> +struct tpmt_ha {
>> + u16 alg_id;
>> + u8 digest[MAX_DIGEST_SIZE];
>> +} __packed;
>> +
>> +/* TPM 2.0 Crypto agile digests list. */
>> +struct tpml_digest_values {
>> + u32 count;
>> + struct tpmt_ha digests[HASH_COUNT];
>> +} __packed;
>> +
>> +/* TPM 2.0 Event field structure. */
>> +struct tcg_event_field {
>> + u32 event_size;
>> + u8 event[MAX_TPM_LOG_MSG];
>> +} __packed;
>> +
>> +/* TPM 2.0 Crypto agile log entry format. */
>> +struct tcg_pcr_event2 {
>> + u32 pcr_idx;
>> + u32 event_type;
>> + struct tpml_digest_values digests;
>> + struct tcg_event_field event;
>> +} __packed;
>
> Your alignment is broken. You sometimes align and sometimes do not.
>
> For struct fields it does not make sense align fields at all since it
> does not "scale". It is done in some places in the driver but for new
> code it is absolutely disallowed. Thus, the right way to fix this is to
> remove all the aligment.
>
> For enums it does make sense and improves readability.
Ok. I didn't change anything in this from previous version, not sure now
why it looks different. Will verify that.
I remembered your feedback for my first version. So, now I don't have
any alignment done for full struct, but have field a tab away from the type.
Thanks & Regards,
- Nayna
>
>> +
>> +extern const struct seq_operations tpm2_binary_b_measurements_seqops;
>> +
>> #if defined(CONFIG_ACPI)
>> int tpm_read_log_acpi(struct tpm_chip *chip);
>> #else
>> --
>> 2.5.0
>
> /Jarkko
>
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