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Message-Id: <20250929035938.1773341-2-jarkko@kernel.org>
Date: Mon, 29 Sep 2025 06:59:30 +0300
From: Jarkko Sakkinen <jarkko@...nel.org>
To: linux-integrity@...r.kernel.org
Cc: dpsmith@...rtussolutions.com,
ross.philipson@...cle.com,
Jarkko Sakkinen <jarkko.sakkinen@...nsys.com>,
Roberto Sassu <roberto.sassu@...wei.com>,
Peter Huewe <peterhuewe@....de>,
Jarkko Sakkinen <jarkko@...nel.org>,
Jason Gunthorpe <jgg@...pe.ca>,
David Howells <dhowells@...hat.com>,
Paul Moore <paul@...l-moore.com>,
James Morris <jmorris@...ei.org>,
"Serge E. Hallyn" <serge@...lyn.com>,
linux-kernel@...r.kernel.org (open list),
keyrings@...r.kernel.org (open list:KEYS/KEYRINGS),
linux-security-module@...r.kernel.org (open list:SECURITY SUBSYSTEM)
Subject: [PATCH v2 1/9] tpm: cap PCR bank in tpm2_get_pcr_allocations()
From: Jarkko Sakkinen <jarkko.sakkinen@...nsys.com>
tpm2_get_pcr_allocation() does not cap any upper limit for the number of
banks received from external hardware device. This could lead into resource
over-consumption with a fauly TPM device.
Cc: Roberto Sassu <roberto.sassu@...wei.com>
Fixes: bcfff8384f6c ("tpm: dynamically allocate the allocated_banks array")
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...nsys.com>
---
v2:
- A new patch.
---
drivers/char/tpm/tpm-chip.c | 13 +++++++++----
drivers/char/tpm/tpm.h | 1 -
drivers/char/tpm/tpm1-cmd.c | 25 -------------------------
drivers/char/tpm/tpm2-cmd.c | 8 +++-----
include/linux/tpm.h | 18 ++++++++----------
5 files changed, 20 insertions(+), 45 deletions(-)
diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index 687f6d8cd601..9a6538f76f50 100644
--- a/drivers/char/tpm/tpm-chip.c
+++ b/drivers/char/tpm/tpm-chip.c
@@ -559,14 +559,19 @@ static int tpm_add_hwrng(struct tpm_chip *chip)
static int tpm_get_pcr_allocation(struct tpm_chip *chip)
{
- int rc;
+ int rc = 0;
if (tpm_is_firmware_upgrade(chip))
return 0;
- rc = (chip->flags & TPM_CHIP_FLAG_TPM2) ?
- tpm2_get_pcr_allocation(chip) :
- tpm1_get_pcr_allocation(chip);
+ if (!(chip->flags & TPM_CHIP_FLAG_TPM2)) {
+ chip->allocated_banks[0].alg_id = TPM_ALG_SHA1;
+ chip->allocated_banks[0].digest_size = hash_digest_size[HASH_ALGO_SHA1];
+ chip->allocated_banks[0].crypto_id = HASH_ALGO_SHA1;
+ chip->nr_allocated_banks = 1;
+ } else {
+ rc = tpm2_get_pcr_allocation(chip);
+ }
if (rc > 0)
return -ENODEV;
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 57ef8589f5f5..769fa6b00c54 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -252,7 +252,6 @@ 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);
int tpm1_get_random(struct tpm_chip *chip, u8 *out, size_t max);
-int tpm1_get_pcr_allocation(struct tpm_chip *chip);
unsigned long tpm_calc_ordinal_duration(struct tpm_chip *chip, u32 ordinal);
int tpm_pm_suspend(struct device *dev);
int tpm_pm_resume(struct device *dev);
diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c
index cf64c7385105..5c49bdff33de 100644
--- a/drivers/char/tpm/tpm1-cmd.c
+++ b/drivers/char/tpm/tpm1-cmd.c
@@ -786,28 +786,3 @@ int tpm1_pm_suspend(struct tpm_chip *chip, u32 tpm_suspend_pcr)
return rc;
}
-
-/**
- * tpm1_get_pcr_allocation() - initialize the allocated bank
- * @chip: TPM chip to use.
- *
- * The function initializes the SHA1 allocated bank to extend PCR
- *
- * Return:
- * * 0 on success,
- * * < 0 on error.
- */
-int tpm1_get_pcr_allocation(struct tpm_chip *chip)
-{
- chip->allocated_banks = kcalloc(1, sizeof(*chip->allocated_banks),
- GFP_KERNEL);
- if (!chip->allocated_banks)
- return -ENOMEM;
-
- chip->allocated_banks[0].alg_id = TPM_ALG_SHA1;
- chip->allocated_banks[0].digest_size = hash_digest_size[HASH_ALGO_SHA1];
- chip->allocated_banks[0].crypto_id = HASH_ALGO_SHA1;
- chip->nr_allocated_banks = 1;
-
- return 0;
-}
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 7d77f6fbc152..e416cc8705e3 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -538,11 +538,9 @@ ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
nr_possible_banks = be32_to_cpup(
(__be32 *)&buf.data[TPM_HEADER_SIZE + 5]);
-
- chip->allocated_banks = kcalloc(nr_possible_banks,
- sizeof(*chip->allocated_banks),
- GFP_KERNEL);
- if (!chip->allocated_banks) {
+ if (nr_possible_banks > TPM2_MAX_BANKS) {
+ pr_err("tpm:: unexpected large number of banks: %u > %u",
+ nr_possible_banks, TPM2_MAX_BANKS);
rc = -ENOMEM;
goto out;
}
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 900c81a2bc41..fc7df87dfb9a 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -27,7 +27,12 @@
#include <crypto/aes.h>
#define TPM_DIGEST_SIZE 20 /* Max TPM v1.2 PCR size */
-#define TPM_MAX_DIGEST_SIZE SHA512_DIGEST_SIZE
+#define TPM_HEADER_SIZE 10
+
+#define TPM2_PLATFORM_PCR 24
+#define TPM2_PCR_SELECT_MIN 3
+#define TPM2_MAX_DIGEST_SIZE SHA512_DIGEST_SIZE
+#define TPM2_MAX_BANKS 4
struct tpm_chip;
struct trusted_key_payload;
@@ -69,7 +74,7 @@ enum tpm2_curves {
struct tpm_digest {
u16 alg_id;
- u8 digest[TPM_MAX_DIGEST_SIZE];
+ u8 digest[TPM2_MAX_DIGEST_SIZE];
} __packed;
struct tpm_bank_info {
@@ -190,7 +195,7 @@ struct tpm_chip {
unsigned int groups_cnt;
u32 nr_allocated_banks;
- struct tpm_bank_info *allocated_banks;
+ struct tpm_bank_info allocated_banks[TPM2_MAX_BANKS];
#ifdef CONFIG_ACPI
acpi_handle acpi_dev_handle;
char ppi_version[TPM_PPI_VERSION_LEN + 1];
@@ -217,13 +222,6 @@ struct tpm_chip {
#endif
};
-#define TPM_HEADER_SIZE 10
-
-enum tpm2_const {
- TPM2_PLATFORM_PCR = 24,
- TPM2_PCR_SELECT_MIN = ((TPM2_PLATFORM_PCR + 7) / 8),
-};
-
enum tpm2_timeouts {
TPM2_TIMEOUT_A = 750,
TPM2_TIMEOUT_B = 4000,
--
2.39.5
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