[PATCH v8 01/11] tpm: Cap the number of PCR banks

[PATCH v8 01/11] tpm: Cap the number of PCR banks

[Jarkko Sakkinen]

From: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>

tpm2_get_pcr_allocation() does not cap any upper limit for the number of
banks. Cap the limit to eight banks so that out of bounds values coming
from external I/O cause on only limited harm.

Cc: Roberto Sassu <roberto.sassu@huawei.com>
Cc: stable@vger.kernel.org # v5.10+
Fixes: bcfff8384f6c ("tpm: dynamically allocate the allocated_banks array")
Reviewed-by: Jonathan McDowell <noodles@meta.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>
---
v8:
- Remove unrelated change of removing tpm1_get_pcr_allocation.
- Add the missing '\n' to the error message.
v7:
- In Ryzen desktop there is total three banks so yep, eight is probably
  much safer bet than four banks. Fixed the commit message as per remark
  from Jonathan:

  https://lore.kernel.org/linux-integrity/aPYg1N0TvrkG6AJI@earth.li/#t

  And with that added also reviewed-by.
v6
- No changes.
v5:
- No changes.
v4:
- Revert spurious changes from include/linux/tpm.h.
- Increase TPM2_MAX_BANKS to 8.
- Rename TPM2_MAX_BANKS as TPM2_MAX_PCR_BANKS for the sake of clarity.
v3:
- Wrote a more clear commit message.
- Fixed pr_err() message.
v2:
- A new patch.
---
 drivers/char/tpm/tpm1-cmd.c | 5 -----
 drivers/char/tpm/tpm2-cmd.c | 8 +++-----
 include/linux/tpm.h         | 8 +++++---
 3 files changed, 8 insertions(+), 13 deletions(-)

diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c
index 11088bda4e68..6849f216ba0b 100644
--- a/drivers/char/tpm/tpm1-cmd.c
+++ b/drivers/char/tpm/tpm1-cmd.c
@@ -799,11 +799,6 @@ int tpm1_pm_suspend(struct tpm_chip *chip, u32 tpm_suspend_pcr)
  */
 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;
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 7d77f6fbc152..5b6ccf901623 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_PCR_BANKS) {
+		pr_err("tpm: out of bank capacity: %u > %u\n",
+		       nr_possible_banks, TPM2_MAX_PCR_BANKS);
 		rc = -ENOMEM;
 		goto out;
 	}
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index dc0338a783f3..eb0ff071bcae 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -26,7 +26,9 @@
 #include <crypto/aes.h>
 
 #define TPM_DIGEST_SIZE 20	/* Max TPM v1.2 PCR size */
-#define TPM_MAX_DIGEST_SIZE SHA512_DIGEST_SIZE
+
+#define TPM2_MAX_DIGEST_SIZE	SHA512_DIGEST_SIZE
+#define TPM2_MAX_PCR_BANKS	8
 
 struct tpm_chip;
 struct trusted_key_payload;
@@ -68,7 +70,7 @@ 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 {
@@ -189,7 +191,7 @@ 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_PCR_BANKS];
 #ifdef CONFIG_ACPI
 	acpi_handle acpi_dev_handle;
 	char ppi_version[TPM_PPI_VERSION_LEN + 1];
-- 
2.52.0

[PATCH v8 04/11] KEYS: trusted: Fix memory leak in tpm2_load()

[Jarkko Sakkinen]

tpm2_load() allocates a blob indirectly via tpm2_key_decode() but it is
not freed in all failure paths. Address this with a scope-based cleanup
helper __free(). For legacy blobs, the implicit de-allocation is gets
disable by no_free_ptr().

Cc: stable@vger.kernel.org # v5.13+
Fixes: f2219745250f ("security: keys: trusted: use ASN.1 TPM2 key format for the blobs")
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
v7:
- Fix compiler warning.
v6:
- A new patch in this version.
---
 security/keys/trusted-keys/trusted_tpm2.c | 24 +++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index edd7b9d7e4dc..36e20a9a94b4 100644
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -98,9 +98,8 @@ struct tpm2_key_context {
 	u32 priv_len;
 };
 
-static int tpm2_key_decode(struct trusted_key_payload *payload,
-			   struct trusted_key_options *options,
-			   u8 **buf)
+static void *tpm2_key_decode(struct trusted_key_payload *payload,
+			     struct trusted_key_options *options)
 {
 	int ret;
 	struct tpm2_key_context ctx;
@@ -111,16 +110,15 @@ static int tpm2_key_decode(struct trusted_key_payload *payload,
 	ret = asn1_ber_decoder(&tpm2key_decoder, &ctx, payload->blob,
 			       payload->blob_len);
 	if (ret < 0)
-		return ret;
+		return ERR_PTR(ret);
 
 	if (ctx.priv_len + ctx.pub_len > MAX_BLOB_SIZE)
-		return -EINVAL;
+		return ERR_PTR(-EINVAL);
 
 	blob = kmalloc(ctx.priv_len + ctx.pub_len + 4, GFP_KERNEL);
 	if (!blob)
-		return -ENOMEM;
+		return ERR_PTR(-ENOMEM);
 
-	*buf = blob;
 	options->keyhandle = ctx.parent;
 
 	memcpy(blob, ctx.priv, ctx.priv_len);
@@ -128,7 +126,7 @@ static int tpm2_key_decode(struct trusted_key_payload *payload,
 
 	memcpy(blob, ctx.pub, ctx.pub_len);
 
-	return 0;
+	return blob;
 }
 
 int tpm2_key_parent(void *context, size_t hdrlen,
@@ -372,6 +370,7 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
 			 struct trusted_key_options *options,
 			 u32 *blob_handle)
 {
+	u8 *blob_ref __free(kfree) = NULL;
 	struct tpm_buf buf;
 	unsigned int private_len;
 	unsigned int public_len;
@@ -380,11 +379,14 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
 	int rc;
 	u32 attrs;
 
-	rc = tpm2_key_decode(payload, options, &blob);
-	if (rc) {
+	blob = tpm2_key_decode(payload, options);
+	if (IS_ERR(blob)) {
 		/* old form */
 		blob = payload->blob;
 		payload->old_format = 1;
+	} else {
+		/* Bind to cleanup: */
+		blob_ref = blob;
 	}
 
 	/* new format carries keyhandle but old format doesn't */
@@ -449,8 +451,6 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
 			(__be32 *) &buf.data[TPM_HEADER_SIZE]);
 
 out:
-	if (blob != payload->blob)
-		kfree(blob);
 	tpm_buf_destroy(&buf);
 
 	if (rc > 0)
-- 
2.52.0