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Date: Thu, 19 Jan 2017 14:48:19 +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 v4 2/2] tpm: enhance TPM 2.0 PCR extend to support
multiple banks
On 01/18/2017 07:28 PM, Jarkko Sakkinen wrote:
> On Wed, Jan 18, 2017 at 03:44:50AM -0500, Nayna Jain wrote:
>> The current TPM 2.0 device driver extends only the SHA1 PCR bank
>> but the TCG Specification[1] recommends extending all active PCR
>> banks, to prevent malicious users from setting unused PCR banks with
>> fake measurements and quoting them.
>>
>> The existing in-kernel interface(tpm_pcr_extend()) expects only a
>> SHA1 digest. To extend all active PCR banks with differing
>> digest sizes, the SHA1 digest is padded with trailing 0's as needed.
>>
>> This patch reuses the defined digest sizes from the crypto subsystem,
>> adding a dependency on CRYPTO_HASH_INFO module.
>>
>> [1] TPM 2.0 Specification referred here is "TCG PC Client Specific
>> Platform Firmware Profile for TPM 2.0"
>>
>> Signed-off-by: Nayna Jain <nayna@...ux.vnet.ibm.com>
>> ---
>> drivers/char/tpm/Kconfig | 1 +
>> drivers/char/tpm/tpm-interface.c | 15 ++++++-
>> drivers/char/tpm/tpm.h | 3 +-
>> drivers/char/tpm/tpm2-cmd.c | 91 +++++++++++++++++++++-------------------
>> drivers/char/tpm/tpm_eventlog.h | 7 ++++
>> 5 files changed, 73 insertions(+), 44 deletions(-)
>>
>> diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig
>> index 277186d..af985cc 100644
>> --- a/drivers/char/tpm/Kconfig
>> +++ b/drivers/char/tpm/Kconfig
>> @@ -6,6 +6,7 @@ menuconfig TCG_TPM
>> tristate "TPM Hardware Support"
>> depends on HAS_IOMEM
>> select SECURITYFS
>> + select CRYPTO_HASH_INFO
>> ---help---
>> If you have a TPM security chip in your system, which
>> implements the Trusted Computing Group's specification,
>> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
>> index a3461cb..00612dd 100644
>> --- a/drivers/char/tpm/tpm-interface.c
>> +++ b/drivers/char/tpm/tpm-interface.c
>> @@ -770,6 +770,7 @@ static const struct tpm_input_header pcrextend_header = {
>> int tpm_pcr_extend(u32 chip_num, int pcr_idx, const u8 *hash)
>> {
>> struct tpm_cmd_t cmd;
>> + int i;
>> int rc;
>> struct tpm_chip *chip;
>>
>> @@ -778,7 +779,19 @@ int tpm_pcr_extend(u32 chip_num, int pcr_idx, const u8 *hash)
>> return -ENODEV;
>>
>> if (chip->flags & TPM_CHIP_FLAG_TPM2) {
>> - rc = tpm2_pcr_extend(chip, pcr_idx, hash);
>> + struct tpm2_digest digest_list[ARRAY_SIZE(chip->active_banks)];
>> + u32 count = 0;
>
> Declare variables in the beginning.
Done, posted new version with this change.
>
>> +
>> + memset(digest_list, 0, sizeof(digest_list));
>> +
>> + for (i = 0; (chip->active_banks[i] != 0) &&
>> + (i < ARRAY_SIZE(chip->active_banks)); i++) {
>> + digest_list[i].alg_id = chip->active_banks[i];
>> + memcpy(digest_list[i].digest, hash, TPM_DIGEST_SIZE);
>> + count++;
>> + }
>> +
>> + rc = tpm2_pcr_extend(chip, pcr_idx, count, digest_list);
>> tpm_put_ops(chip);
>> return rc;
>> }
>> diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
>> index dddd573..f578822 100644
>> --- a/drivers/char/tpm/tpm.h
>> +++ b/drivers/char/tpm/tpm.h
>> @@ -533,7 +533,8 @@ static inline void tpm_add_ppi(struct tpm_chip *chip)
>> #endif
>>
>> int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx, u8 *res_buf);
>> -int tpm2_pcr_extend(struct tpm_chip *chip, int pcr_idx, const u8 *hash);
>> +int tpm2_pcr_extend(struct tpm_chip *chip, int pcr_idx, u32 count,
>> + struct tpm2_digest *digests);
>> int tpm2_get_random(struct tpm_chip *chip, u8 *out, size_t max);
>> int tpm2_seal_trusted(struct tpm_chip *chip,
>> struct trusted_key_payload *payload,
>> diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
>> index 75a7546..7ceebbd 100644
>> --- a/drivers/char/tpm/tpm2-cmd.c
>> +++ b/drivers/char/tpm/tpm2-cmd.c
>> @@ -53,22 +53,6 @@ struct tpm2_pcr_read_out {
>> u8 digest[TPM_DIGEST_SIZE];
>> } __packed;
>>
>> -struct tpm2_null_auth_area {
>> - __be32 handle;
>> - __be16 nonce_size;
>> - u8 attributes;
>> - __be16 auth_size;
>> -} __packed;
>> -
>> -struct tpm2_pcr_extend_in {
>> - __be32 pcr_idx;
>> - __be32 auth_area_size;
>> - struct tpm2_null_auth_area auth_area;
>> - __be32 digest_cnt;
>> - __be16 hash_alg;
>> - u8 digest[TPM_DIGEST_SIZE];
>> -} __packed;
>> -
>> struct tpm2_get_tpm_pt_in {
>> __be32 cap_id;
>> __be32 property_id;
>> @@ -97,7 +81,6 @@ union tpm2_cmd_params {
>> struct tpm2_self_test_in selftest_in;
>> struct tpm2_pcr_read_in pcrread_in;
>> struct tpm2_pcr_read_out pcrread_out;
>> - struct tpm2_pcr_extend_in pcrextend_in;
>> struct tpm2_get_tpm_pt_in get_tpm_pt_in;
>> struct tpm2_get_tpm_pt_out get_tpm_pt_out;
>> struct tpm2_get_random_in getrandom_in;
>> @@ -290,46 +273,68 @@ int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx, u8 *res_buf)
>> return rc;
>> }
>>
>> -#define TPM2_GET_PCREXTEND_IN_SIZE \
>> - (sizeof(struct tpm_input_header) + \
>> - sizeof(struct tpm2_pcr_extend_in))
>> -
>> -static const struct tpm_input_header tpm2_pcrextend_header = {
>> - .tag = cpu_to_be16(TPM2_ST_SESSIONS),
>> - .length = cpu_to_be32(TPM2_GET_PCREXTEND_IN_SIZE),
>> - .ordinal = cpu_to_be32(TPM2_CC_PCR_EXTEND)
>> -};
>> +struct tpm2_null_auth_area {
>> + __be32 handle;
>> + __be16 nonce_size;
>> + u8 attributes;
>> + __be16 auth_size;
>> +} __packed;
>>
>> /**
>> * tpm2_pcr_extend() - extend a PCR value
>> *
>> * @chip: TPM chip to use.
>> * @pcr_idx: index of the PCR.
>> - * @hash: hash value to use for the extend operation.
>> + * @count: number of digests passed.
>> + * @digests: list of pcr banks and corresponding digest values to extend.
>> *
>> * Return: Same as with tpm_transmit_cmd.
>> *
>> -int tpm2_pcr_extend(struct tpm_chip *chip, int pcr_idx, const u8 *hash)
>> +int tpm2_pcr_extend(struct tpm_chip *chip, int pcr_idx, u32 count,
>> + struct tpm2_digest *digests)
>
> Yes, this much much better. Now you can understand what is happening
> even if you never have read the TPM 2.0 spec.
Yeah.. I agree..
Thanks & Regards,
- Nayna
>
>> {
>> - struct tpm2_cmd cmd;
>> + struct tpm_buf buf;
>> + struct tpm2_null_auth_area auth_area;
>> int rc;
>> + int i;
>> + int j;
>>
>> - cmd.header.in = tpm2_pcrextend_header;
>> - cmd.params.pcrextend_in.pcr_idx = cpu_to_be32(pcr_idx);
>> - cmd.params.pcrextend_in.auth_area_size =
>> - cpu_to_be32(sizeof(struct tpm2_null_auth_area));
>> - cmd.params.pcrextend_in.auth_area.handle =
>> - cpu_to_be32(TPM2_RS_PW);
>> - cmd.params.pcrextend_in.auth_area.nonce_size = 0;
>> - cmd.params.pcrextend_in.auth_area.attributes = 0;
>> - cmd.params.pcrextend_in.auth_area.auth_size = 0;
>> - cmd.params.pcrextend_in.digest_cnt = cpu_to_be32(1);
>> - cmd.params.pcrextend_in.hash_alg = cpu_to_be16(TPM2_ALG_SHA1);
>> - memcpy(cmd.params.pcrextend_in.digest, hash, TPM_DIGEST_SIZE);
>> + if (count > ARRAY_SIZE(chip->active_banks))
>> + return -EINVAL;
>>
>> - rc = tpm_transmit_cmd(chip, &cmd, sizeof(cmd), 0,
>> + rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND);
>> + if (rc)
>> + return rc;
>> +
>> + tpm_buf_append_u32(&buf, pcr_idx);
>> +
>> + auth_area.handle = cpu_to_be32(TPM2_RS_PW);
>> + auth_area.nonce_size = 0;
>> + auth_area.attributes = 0;
>> + auth_area.auth_size = 0;
>> +
>> + tpm_buf_append_u32(&buf, sizeof(struct tpm2_null_auth_area));
>> + tpm_buf_append(&buf, (const unsigned char *)&auth_area,
>> + sizeof(auth_area));
>> + tpm_buf_append_u32(&buf, count);
>> +
>> + for (i = 0; i < count; i++) {
>> + for (j = 0; j < ARRAY_SIZE(tpm2_hash_map); j++) {
>> + if (digests[i].alg_id != tpm2_hash_map[j].tpm_id)
>> + continue;
>> +
>> + tpm_buf_append_u16(&buf, digests[i].alg_id);
>> + tpm_buf_append(&buf, (const unsigned char
>> + *)&digests[i].digest,
>> + hash_digest_size[tpm2_hash_map[j].crypto_id]);
>> + }
>> + }
>> +
>> + rc = tpm_transmit_cmd(chip, buf.data, tpm_buf_length(&buf), 0,
>> "attempting extend a PCR value");
>>
>> + tpm_buf_destroy(&buf);
>> +
>> return rc;
>> }
>>
>> @@ -993,6 +998,8 @@ int tpm2_auto_startup(struct tpm_chip *chip)
>> }
>> }
>>
>> + rc = tpm2_get_pcr_allocation(chip);
>> +
>> out:
>> if (rc > 0)
>> rc = -ENODEV;
>> diff --git a/drivers/char/tpm/tpm_eventlog.h b/drivers/char/tpm/tpm_eventlog.h
>> index 1660d74..b5ae372 100644
>> --- a/drivers/char/tpm/tpm_eventlog.h
>> +++ b/drivers/char/tpm/tpm_eventlog.h
>> @@ -2,6 +2,8 @@
>> #ifndef __TPM_EVENTLOG_H__
>> #define __TPM_EVENTLOG_H__
>>
>> +#include <crypto/hash_info.h>
>> +
>> #define TCG_EVENT_NAME_LEN_MAX 255
>> #define MAX_TEXT_EVENT 1000 /* Max event string length */
>> #define ACPI_TCPA_SIG "TCPA" /* 0x41504354 /'TCPA' */
>> @@ -73,6 +75,11 @@ enum tcpa_pc_event_ids {
>> HOST_TABLE_OF_DEVICES,
>> };
>>
>> +struct tpm2_digest {
>> + u16 alg_id;
>> + u8 digest[SHA512_DIGEST_SIZE];
>> +} __packed;
>> +
>> #if defined(CONFIG_ACPI)
>> int tpm_read_log_acpi(struct tpm_chip *chip);
>> #else
>> --
>> 2.5.0
>
> Otherwise,
>
> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
>
> /Jarkko
>
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