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Subject[PATCH v5 4/7] tpm: modify tpm_pcr_read() definition to pass a TPM hash algorithm
Date
Currently the TPM driver allows other kernel subsystems to read only the
SHA1 PCR bank. This patch modifies the parameters of tpm_pcr_read() and
tpm2_pcr_read() to pass a tpm_digest structure, which contains the desired
hash algorithm. Also, since commit 125a22105410 ("tpm: React correctly to
RC_TESTING from TPM 2.0 self tests") removed the call to tpm2_pcr_read(),
the new parameter is expected to be always not NULL.

Due to the API change, IMA functions have been modified.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Acked-by: Mimi Zohar <zohar@linux.ibm.com>
---
drivers/char/tpm/tpm-interface.c | 9 +++++----
drivers/char/tpm/tpm.h | 3 ++-
drivers/char/tpm/tpm2-cmd.c | 23 ++++++++++++++++-------
include/linux/tpm.h | 6 ++++--
security/integrity/ima/ima_crypto.c | 10 +++++-----
5 files changed, 32 insertions(+), 19 deletions(-)

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 96c8261d0f04..04aa39432f58 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -451,11 +451,12 @@ EXPORT_SYMBOL_GPL(tpm_is_tpm2);
* tpm_pcr_read - read a PCR value from SHA1 bank
* @chip: a &struct tpm_chip instance, %NULL for the default chip
* @pcr_idx: the PCR to be retrieved
- * @res_buf: the value of the PCR
+ * @digest_struct: the PCR bank and buffer current PCR value is written to
*
* Return: same as with tpm_transmit_cmd()
*/
-int tpm_pcr_read(struct tpm_chip *chip, u32 pcr_idx, u8 *res_buf)
+int tpm_pcr_read(struct tpm_chip *chip, u32 pcr_idx,
+ struct tpm_digest *digest_struct)
{
int rc;

@@ -464,9 +465,9 @@ int tpm_pcr_read(struct tpm_chip *chip, u32 pcr_idx, u8 *res_buf)
return -ENODEV;

if (chip->flags & TPM_CHIP_FLAG_TPM2)
- rc = tpm2_pcr_read(chip, pcr_idx, res_buf);
+ rc = tpm2_pcr_read(chip, pcr_idx, digest_struct);
else
- rc = tpm1_pcr_read(chip, pcr_idx, res_buf);
+ rc = tpm1_pcr_read(chip, pcr_idx, digest_struct->digest);

tpm_put_ops(chip);
return rc;
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index e961e5c5d197..33b293da69d6 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -548,7 +548,8 @@ static inline u32 tpm2_rc_value(u32 rc)
}

int tpm2_get_timeouts(struct tpm_chip *chip);
-int tpm2_pcr_read(struct tpm_chip *chip, u32 pcr_idx, u8 *res_buf);
+int tpm2_pcr_read(struct tpm_chip *chip, u32 pcr_idx,
+ struct tpm_digest *digest_struct);
int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, u32 count,
struct tpm_digest *digests);
int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max);
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 4afd14892cbf..0d72c2f98bd6 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -171,16 +171,18 @@ struct tpm2_pcr_read_out {
* tpm2_pcr_read() - read a PCR value
* @chip: TPM chip to use.
* @pcr_idx: index of the PCR to read.
- * @res_buf: buffer to store the resulting hash.
+ * @digest_struct: PCR bank and buffer current PCR value is written to.
*
* Return: Same as with tpm_transmit_cmd.
*/
-int tpm2_pcr_read(struct tpm_chip *chip, u32 pcr_idx, u8 *res_buf)
+int tpm2_pcr_read(struct tpm_chip *chip, u32 pcr_idx,
+ struct tpm_digest *digest_struct)
{
int rc;
struct tpm_buf buf;
struct tpm2_pcr_read_out *out;
u8 pcr_select[TPM2_PCR_SELECT_MIN] = {0};
+ u16 digest_size;

if (pcr_idx >= TPM2_PLATFORM_PCR)
return -EINVAL;
@@ -192,18 +194,25 @@ int tpm2_pcr_read(struct tpm_chip *chip, u32 pcr_idx, u8 *res_buf)
pcr_select[pcr_idx >> 3] = 1 << (pcr_idx & 0x7);

tpm_buf_append_u32(&buf, 1);
- tpm_buf_append_u16(&buf, TPM_ALG_SHA1);
+ tpm_buf_append_u16(&buf, digest_struct->alg_id);
tpm_buf_append_u8(&buf, TPM2_PCR_SELECT_MIN);
tpm_buf_append(&buf, (const unsigned char *)pcr_select,
sizeof(pcr_select));

rc = tpm_transmit_cmd(chip, NULL, buf.data, PAGE_SIZE, 0, 0,
- res_buf ? "attempting to read a pcr value" : NULL);
- if (rc == 0 && res_buf) {
- out = (struct tpm2_pcr_read_out *)&buf.data[TPM_HEADER_SIZE];
- memcpy(res_buf, out->digest, SHA1_DIGEST_SIZE);
+ "attempting to read a pcr value");
+ if (rc)
+ goto out;
+
+ out = (struct tpm2_pcr_read_out *)&buf.data[TPM_HEADER_SIZE];
+ digest_size = be16_to_cpu(out->digest_size);
+ if (digest_size > sizeof(digest_struct->digest)) {
+ rc = -EINVAL;
+ goto out;
}

+ memcpy(digest_struct->digest, out->digest, digest_size);
+out:
tpm_buf_destroy(&buf);
return rc;
}
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 330c0a481581..077fd31783ad 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -71,7 +71,8 @@ struct tpm_class_ops {
#if defined(CONFIG_TCG_TPM) || defined(CONFIG_TCG_TPM_MODULE)

extern int tpm_is_tpm2(struct tpm_chip *chip);
-extern int tpm_pcr_read(struct tpm_chip *chip, u32 pcr_idx, u8 *res_buf);
+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_send(struct tpm_chip *chip, void *cmd, size_t buflen);
extern int tpm_get_random(struct tpm_chip *chip, u8 *data, size_t max);
@@ -88,7 +89,8 @@ static inline int tpm_is_tpm2(struct tpm_chip *chip)
return -ENODEV;
}

-static inline int tpm_pcr_read(struct tpm_chip *chip, u32 pcr_idx, u8 *res_buf)
+static inline int tpm_pcr_read(struct tpm_chip *chip, int pcr_idx,
+ struct tpm_digest *digest_struct)
{
return -ENODEV;
}
diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c
index acf2c7df7145..16a4f45863b1 100644
--- a/security/integrity/ima/ima_crypto.c
+++ b/security/integrity/ima/ima_crypto.c
@@ -643,12 +643,12 @@ int ima_calc_buffer_hash(const void *buf, loff_t len,
return calc_buffer_shash(buf, len, hash);
}

-static void __init ima_pcrread(u32 idx, u8 *pcr)
+static void __init ima_pcrread(u32 idx, struct tpm_digest *d)
{
if (!ima_tpm_chip)
return;

- if (tpm_pcr_read(ima_tpm_chip, idx, pcr) != 0)
+ if (tpm_pcr_read(ima_tpm_chip, idx, d) != 0)
pr_err("Error Communicating to TPM chip\n");
}

@@ -658,7 +658,7 @@ static void __init ima_pcrread(u32 idx, u8 *pcr)
static int __init ima_calc_boot_aggregate_tfm(char *digest,
struct crypto_shash *tfm)
{
- u8 pcr_i[TPM_DIGEST_SIZE];
+ struct tpm_digest d = { .alg_id = TPM_ALG_SHA1, .digest = {0} };
int rc;
u32 i;
SHASH_DESC_ON_STACK(shash, tfm);
@@ -672,9 +672,9 @@ static int __init ima_calc_boot_aggregate_tfm(char *digest,

/* cumulative sha1 over tpm registers 0-7 */
for (i = TPM_PCR0; i < TPM_PCR8; i++) {
- ima_pcrread(i, pcr_i);
+ ima_pcrread(i, &d);
/* now accumulate with current aggregate */
- rc = crypto_shash_update(shash, pcr_i, TPM_DIGEST_SIZE);
+ rc = crypto_shash_update(shash, d.digest, TPM_DIGEST_SIZE);
}
if (!rc)
crypto_shash_final(shash, digest);
--
2.17.1
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