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Date: Tue, 24 Jan 2017 18:34:54 +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: enhance TPM 2.0 PCR extend to support
multiple banks
On 01/24/2017 05:29 PM, Jarkko Sakkinen wrote:
> On Mon, Jan 23, 2017 at 10:11:48PM +0530, Nayna wrote:
>>
>>
>> On 01/23/2017 08:49 PM, Jarkko Sakkinen wrote:
>>> On Fri, Jan 20, 2017 at 12:05:13PM -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>
>>>> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.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..cf959c3 100644
>>>> --- a/drivers/char/tpm/tpm-interface.c
>>>> +++ b/drivers/char/tpm/tpm-interface.c
>>>> @@ -772,13 +772,26 @@ int tpm_pcr_extend(u32 chip_num, int pcr_idx, const u8 *hash)
>>>> struct tpm_cmd_t cmd;
>>>> int rc;
>>>> struct tpm_chip *chip;
>>>> + int max_active_banks = ARRAY_SIZE(chip->active_banks);
>>>> + struct tpm2_digest digest_list[max_active_banks];
>>>> + u32 count = 0;
>>>> + int i;
>>>>
>>>> chip = tpm_chip_find_get(chip_num);
>>>> if (chip == NULL)
>>>> return -ENODEV;
>>>>
>>>> if (chip->flags & TPM_CHIP_FLAG_TPM2) {
>>>> - rc = tpm2_pcr_extend(chip, pcr_idx, hash);
>>>> + memset(digest_list, 0, sizeof(digest_list));
>>>> +
>>>> + for (i = 0; (chip->active_banks[i] != TPM2_ALG_ERROR) &&
>>>> + (i < max_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 c291f19..07a0677 100644
>>>> --- a/drivers/char/tpm/tpm.h
>>>> +++ b/drivers/char/tpm/tpm.h
>>>> @@ -534,7 +534,8 @@ 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 0e000a3..d78adb8 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)
>>>> {
>>>> - struct tpm2_cmd cmd;
>>>> + struct tpm_buf buf;
>>>> + struct tpm2_null_auth_area auth_area;
>>>> int rc;
>>>> + int i;
>>>> + int j;
>>>> +
>>>> + if (count > ARRAY_SIZE(chip->active_banks))
>>>> + return -EINVAL;
>>>>
>>>> - 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);
>>>> + rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND);
>>>> + if (rc)
>>>> + return rc;
>>>>
>>>> - rc = tpm_transmit_cmd(chip, &cmd, sizeof(cmd), 0,
>>>> + 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;
>>>
>>> Shouldn't this be in tpm.h?
>>
>> This is a struct common for TPM 2.0 extend and eventlog structure i.e
>> struct tcg_pcr_event2.
>> And so I preferred to place it here.
>>
>
> If it is common, why is it in tpm_eventlog.h and not in tpm.h?
Hmm, the way I took it was that all event log structs are in
tpm_eventlog.h. So, I have defined all structs related to event log into
tpm_eventlog.h, including this one.
Also, currently, tpm_eventlog.h has no dependency on tpm.h, but tpm.h
does include tpm_eventlog.h.
Hmm.. is it an issue to have it in tpm_eventlog.h ?
Thanks & Regards,
- Nayna
>
>> Thanks & Regards,
>> - Nayna
>
> /Jarkko
>
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