[PATCH v5 7/7] tpm: pass an array of tpm_bank_list structures to tpm_pcr_extend()

From: Roberto Sassu
Date: Wed Nov 14 2018 - 10:37:20 EST

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In reply to: Roberto Sassu: "[PATCH v5 6/7] tpm: ensure that the output of PCR read contains the correct digest size"
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Currently, tpm_pcr_extend() accepts as an input only a SHA1 digest.

This patch modifies the definition of tpm_pcr_extend() to allow other
kernel subsystems to pass a digest for each algorithm supported by the TPM.
All digests are processed by the TPM in one operation.

If a tpm_pcr_extend() caller provides a subset of the supported algorithms,
the TPM driver extends the remaining PCR banks with the first digest
passed as an argument to the function.

The new tpm_bank_list structure has been preferred to the tpm_digest
structure, to let the caller specify the size of the digest (which may be
unknown to the TPM driver).

Due to the API change, ima_pcr_extend() and pcrlock() have been modified.

Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
---
drivers/char/tpm/tpm-interface.c | 24 +++++---------------
drivers/char/tpm/tpm.h | 6 ++---
drivers/char/tpm/tpm1-cmd.c | 14 ++++++++----
drivers/char/tpm/tpm2-cmd.c | 36 +++++++++++++++++++++---------
include/linux/tpm.h | 13 ++++++++---
security/integrity/ima/ima_queue.c | 5 ++++-
security/keys/trusted.c | 5 ++++-
7 files changed, 63 insertions(+), 40 deletions(-)

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index f0e1456440d7..5495223d3f7b 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -478,42 +478,30 @@ EXPORT_SYMBOL_GPL(tpm_pcr_read);
* tpm_pcr_extend - extend a PCR value in SHA1 bank.
* @chip: a &struct tpm_chip instance, %NULL for the default chip
* @pcr_idx: the PCR to be retrieved
- * @hash: the hash value used to extend the PCR value
+ * @count: number of tpm_bank_list structures
+ * @bank_list: array of tpm_bank_list structures used to extend the PCR value
*
* Note: with TPM 2.0 extends also those banks for which no digest was
* specified in order to prevent malicious use of those PCR banks.
*
* Return: same as with tpm_transmit_cmd()
*/
-int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, const u8 *hash)
+int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, u32 count,
+ const struct tpm_bank_list *bank_list)
{
int rc;
- struct tpm_digest *digest_list;
- int i;

chip = tpm_find_get_ops(chip);
if (!chip)
return -ENODEV;

if (chip->flags & TPM_CHIP_FLAG_TPM2) {
- digest_list = kcalloc(chip->nr_allocated_banks,
- sizeof(*digest_list), GFP_KERNEL);
- if (!digest_list)
- return -ENOMEM;
-
- for (i = 0; i < chip->nr_allocated_banks; i++) {
- digest_list[i].alg_id = chip->allocated_banks[i].alg_id;
- memcpy(digest_list[i].digest, hash, TPM_DIGEST_SIZE);
- }
-
- rc = tpm2_pcr_extend(chip, pcr_idx, chip->nr_allocated_banks,
- digest_list);
- kfree(digest_list);
+ rc = tpm2_pcr_extend(chip, pcr_idx, count, bank_list);
tpm_put_ops(chip);
return rc;
}

- rc = tpm1_pcr_extend(chip, pcr_idx, hash,
+ rc = tpm1_pcr_extend(chip, pcr_idx, count, bank_list,
"attempting extend a PCR value");
tpm_put_ops(chip);
return rc;
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 023ddf42038b..4296c720ebb4 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -504,8 +504,8 @@ int tpm1_auto_startup(struct tpm_chip *chip);
int tpm1_do_selftest(struct tpm_chip *chip);
int tpm1_get_timeouts(struct tpm_chip *chip);
unsigned long tpm1_calc_ordinal_duration(struct tpm_chip *chip, u32 ordinal);
-int tpm1_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, const u8 *hash,
- const char *log_msg);
+int tpm1_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, u32 count,
+ const struct tpm_bank_list *bank_list, const char *log_msg);
int tpm1_pcr_read(struct tpm_chip *chip, u32 pcr_idx, u8 *res_buf);
ssize_t tpm1_getcap(struct tpm_chip *chip, u32 subcap_id, cap_t *cap,
const char *desc, size_t min_cap_length);
@@ -551,7 +551,7 @@ int tpm2_get_timeouts(struct tpm_chip *chip);
int tpm2_pcr_read(struct tpm_chip *chip, u32 pcr_idx,
struct tpm_digest *digest_struct, u16 *digest_size_ptr);
int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, u32 count,
- struct tpm_digest *digests);
+ const struct tpm_bank_list *bank_list);
int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max);
void tpm2_flush_context_cmd(struct tpm_chip *chip, u32 handle,
unsigned int flags);
diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c
index 8b70a7f884a7..439ac749517c 100644
--- a/drivers/char/tpm/tpm1-cmd.c
+++ b/drivers/char/tpm/tpm1-cmd.c
@@ -449,12 +449,19 @@ int tpm1_get_timeouts(struct tpm_chip *chip)
}

#define TPM_ORD_PCR_EXTEND 20
-int tpm1_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, const u8 *hash,
- const char *log_msg)
+int tpm1_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, u32 count,
+ const struct tpm_bank_list *bank_list, const char *log_msg)
{
struct tpm_buf buf;
+ u8 dummy_hash[TPM_DIGEST_SIZE] = { 0 };
+ const u8 *hash;
int rc;

+ hash = dummy_hash;
+ if (count)
+ memcpy(dummy_hash, bank_list[0].extend_array,
+ min(bank_list[0].digest_size, (u16)sizeof(dummy_hash)));
+
rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_PCR_EXTEND);
if (rc)
return rc;
@@ -743,7 +750,6 @@ int tpm1_auto_startup(struct tpm_chip *chip)
*/
int tpm1_pm_suspend(struct tpm_chip *chip, u32 tpm_suspend_pcr)
{
- u8 dummy_hash[TPM_DIGEST_SIZE] = { 0 };
struct tpm_buf buf;
unsigned int try;
int rc;
@@ -751,7 +757,7 @@ int tpm1_pm_suspend(struct tpm_chip *chip, u32 tpm_suspend_pcr)

/* for buggy tpm, flush pcrs with extend to selected dummy */
if (tpm_suspend_pcr)
- rc = tpm1_pcr_extend(chip, tpm_suspend_pcr, dummy_hash,
+ rc = tpm1_pcr_extend(chip, tpm_suspend_pcr, 0, NULL,
"extending dummy pcr before suspend");

rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_SAVESTATE);
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 974465f04b78..40eb1a044451 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -248,21 +248,22 @@ struct tpm2_null_auth_area {
*
* @chip: TPM chip to use.
* @pcr_idx: index of the PCR.
- * @count: number of digests passed.
- * @digests: list of pcr banks and corresponding digest values to extend.
+ * @count: number of tpm_bank_list passed.
+ * @bank_list: array of tpm_bank_list with digest values to extend.
*
* Return: Same as with tpm_transmit_cmd.
*/
int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, u32 count,
- struct tpm_digest *digests)
+ const struct tpm_bank_list *bank_list)
{
struct tpm_buf buf;
struct tpm2_null_auth_area auth_area;
+ const struct tpm_bank_list *item;
+ u8 dummy_hash[SHA512_DIGEST_SIZE] = { 0 };
+ const u8 *hash;
int rc;
int i;
-
- if (count > chip->nr_allocated_banks)
- return -EINVAL;
+ int j;

rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND);
if (rc)
@@ -278,11 +279,26 @@ int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, u32 count,
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);
+ tpm_buf_append_u32(&buf, chip->nr_allocated_banks);
+
+ if (count)
+ memcpy(dummy_hash, bank_list[0].extend_array,
+ bank_list[0].digest_size);
+
+ for (i = 0; i < chip->nr_allocated_banks; i++) {
+ tpm_buf_append_u16(&buf, chip->allocated_banks[i].alg_id);
+
+ hash = dummy_hash;
+ for (j = 0; j < count; j++) {
+ item = bank_list + j;
+
+ if (item->alg_id == chip->allocated_banks[i].alg_id) {
+ hash = item->extend_array;
+ break;
+ }
+ }

- for (i = 0; i < count; i++) {
- tpm_buf_append_u16(&buf, digests[i].alg_id);
- tpm_buf_append(&buf, (const unsigned char *)&digests[i].digest,
+ tpm_buf_append(&buf, hash,
chip->allocated_banks[i].digest_size);
}

diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index fcdd33ae9969..16e5ff1f0294 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -52,6 +52,12 @@ struct tpm_bank_info {
u16 crypto_id;
};

+struct tpm_bank_list {
+ u8 alg_id;
+ u16 digest_size;
+ const u8 *extend_array;
+};
+
enum TPM_OPS_FLAGS {
TPM_OPS_AUTO_STARTUP = BIT(0),
};
@@ -79,7 +85,8 @@ struct tpm_class_ops {
extern int tpm_is_tpm2(struct tpm_chip *chip);
extern int tpm_pcr_read(struct tpm_chip *chip, u32 pcr_idx,
struct tpm_digest *digest_struct);
-extern int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, const u8 *hash);
+extern int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, u32 count,
+ const struct tpm_bank_list *bank_list);
extern int tpm_send(struct tpm_chip *chip, void *cmd, size_t buflen);
extern int tpm_get_random(struct tpm_chip *chip, u8 *data, size_t max);
extern int tpm_seal_trusted(struct tpm_chip *chip,
@@ -101,8 +108,8 @@ static inline int tpm_pcr_read(struct tpm_chip *chip, int pcr_idx,
return -ENODEV;
}

-static inline int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
- const u8 *hash)
+static inline int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, u32 count,
+ const struct tpm_bank_list *bank_list)
{
return -ENODEV;
}
diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c
index b186819bd5aa..24024edef316 100644
--- a/security/integrity/ima/ima_queue.c
+++ b/security/integrity/ima/ima_queue.c
@@ -140,12 +140,15 @@ unsigned long ima_get_binary_runtime_size(void)

static int ima_pcr_extend(const u8 *hash, int pcr)
{
+ struct tpm_bank_list bank_item = { .alg_id = TPM_ALG_SHA1,
+ .digest_size = TPM_DIGEST_SIZE,
+ .extend_array = hash };
int result = 0;

if (!ima_tpm_chip)
return result;

- result = tpm_pcr_extend(ima_tpm_chip, pcr, hash);
+ result = tpm_pcr_extend(ima_tpm_chip, pcr, 1, &bank_item);
if (result != 0)
pr_err("Error Communicating to TPM chip, result: %d\n", result);
return result;
diff --git a/security/keys/trusted.c b/security/keys/trusted.c
index ff6789365a12..d2a3129a95f9 100644
--- a/security/keys/trusted.c
+++ b/security/keys/trusted.c
@@ -380,6 +380,9 @@ EXPORT_SYMBOL_GPL(trusted_tpm_send);
static int pcrlock(const int pcrnum)
{
unsigned char hash[SHA1_DIGEST_SIZE];
+ struct tpm_bank_list bank_item = { .alg_id = TPM_ALG_SHA1,
+ .digest_size = sizeof(hash),
+ .extend_array = hash }
int ret;

if (!capable(CAP_SYS_ADMIN))
@@ -387,7 +390,7 @@ static int pcrlock(const int pcrnum)
ret = tpm_get_random(NULL, hash, SHA1_DIGEST_SIZE);
if (ret != SHA1_DIGEST_SIZE)
return ret;
- return tpm_pcr_extend(NULL, pcrnum, hash) ? -EINVAL : 0;
+ return tpm_pcr_extend(NULL, pcrnum, 1, &bank_item) ? -EINVAL : 0;
}

/*
--
2.17.1

Next message: Christoph Hellwig: "Re: [PATCH v3 2/3] MIPS: SiByte: Enable ZONE_DMA32 for LittleSur"
Previous message: Christoph Hellwig: "Re: [PATCH v3 1/3] MIPS: SiByte: Set 32-bit bus mask for BCM1250 PCI"
In reply to: Roberto Sassu: "[PATCH v5 6/7] tpm: ensure that the output of PCR read contains the correct digest size"
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