[PATCH v3 5/6] tpm: introduce tpm_get_pcr_banks_info()

Roberto Sassu
2017-06-21T14:34:52Z

This function copies the array of tpm_pcr_bank_info structures to the
memory address specified by the caller. It assumes that the caller
allocated an array with the same number of elements of the active_banks
array (member of the tpm_chip structure). This number is defined in
include/linux/tpm.h (TPM_ACTIVE_BANKS_MAX definition).

A tpm_pcr_bank_info structure is also returned if the TPM version is 1.2.
The advantage of this choice is that the code for extending a PCR with
multiple digests will work regardless of the TPM version.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
drivers/char/tpm/tpm-interface.c | 33 +++++++++++++++++++++++++++++++++
drivers/char/tpm/tpm.h | 2 +-
include/linux/tpm.h | 8 ++++++++
3 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index a11598a..cf0cdb2 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -916,6 +916,39 @@ int tpm_pcr_extend(u32 chip_num, int pcr_idx, const u8 *hash)
EXPORT_SYMBOL_GPL(tpm_pcr_extend);

/**
+ * tpm_get_pcr_banks_info() - get PCR banks information
+ * @chip_num: tpm idx # or ANY
+ * @active_banks: array of tpm_pcr_bank_info structures
+ *
+ * Return: < 0 on error, and the number of active PCR banks on success.
+ */
+int tpm_get_pcr_banks_info(u32 chip_num, struct tpm_pcr_bank_info *active_banks)
+{
+ struct tpm_chip *chip;
+ int count = 1;
+
+ chip = tpm_chip_find_get(chip_num);
+ if (chip == NULL)
+ return -ENODEV;
+
+ if (!(chip->flags & TPM_CHIP_FLAG_TPM2)) {
+ active_banks[0].alg_id = TPM2_ALG_SHA1;
+ active_banks[0].crypto_id = HASH_ALGO_SHA1;
+ active_banks[0].digest_size = hash_digest_size[HASH_ALGO_SHA1];
+ goto out;
+ }
+
+ for (count = 0; count < ARRAY_SIZE(chip->active_banks) &&
+ chip->active_banks[count].alg_id != TPM2_ALG_ERROR; count++)
+ memcpy(&active_banks[count], &chip->active_banks[count],
+ sizeof(*active_banks));
+out:
+ tpm_put_ops(chip);
+ return count;
+}
+EXPORT_SYMBOL_GPL(tpm_get_pcr_banks_info);
+
+/**
* tpm_do_selftest - have the TPM continue its selftest and wait until it
* can receive further commands
* @chip: TPM chip to use
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index d285bc6..75ec0d1 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -208,7 +208,7 @@ struct tpm_chip {
const struct attribute_group *groups[3];
unsigned int groups_cnt;

- struct tpm_pcr_bank_info active_banks[7];
+ struct tpm_pcr_bank_info active_banks[TPM_ACTIVE_BANKS_MAX];
#ifdef CONFIG_ACPI
acpi_handle acpi_dev_handle;
char ppi_version[TPM_PPI_VERSION_LEN + 1];
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index ff06738..49ec8fc 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -25,6 +25,7 @@
#include <crypto/hash_info.h>

#define TPM_DIGEST_SIZE 20 /* Max TPM v1.2 PCR size */
+#define TPM_ACTIVE_BANKS_MAX 7 /* Max num of active banks for TPM 2.0 */

/*
* Chip num is this value or a valid tpm idx
@@ -76,6 +77,8 @@ struct tpm_pcr_bank_info {
extern int tpm_is_tpm2(u32 chip_num);
extern int tpm_pcr_read(u32 chip_num, int pcr_idx, u8 *res_buf);
extern int tpm_pcr_extend(u32 chip_num, int pcr_idx, const u8 *hash);
+extern int tpm_get_pcr_banks_info(u32 chip_num,
+ struct tpm_pcr_bank_info *active_banks);
extern int tpm_send(u32 chip_num, void *cmd, size_t buflen);
extern int tpm_get_random(u32 chip_num, u8 *data, size_t max);
extern int tpm_seal_trusted(u32 chip_num,
@@ -95,6 +98,11 @@ static inline int tpm_pcr_read(u32 chip_num, int pcr_idx, u8 *res_buf) {
static inline int tpm_pcr_extend(u32 chip_num, int pcr_idx, const u8 *hash) {
return -ENODEV;
}
+static inline int tpm_get_pcr_banks_info(u32 chip_num,
+ struct tpm_pcr_bank_info *active_banks)
+{
+ return -ENODEV;
+}
static inline int tpm_send(u32 chip_num, void *cmd, size_t buflen) {
return -ENODEV;
}
--
2.9.3