[PATCH 3/4] tpm: seal/unseal for TPM 2.0

[Jarkko Sakkinen]

Added tpm_trusted_seal() and tpm_trusted_unseal() API for sealing
trusted keys.

This patch implements basic sealing and unsealing functionality for
TPM 2.0:

* Seal with a parent key using a 20 byte auth value.
* Unseal with a parent key using a 20 byte auth value.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
---
 drivers/char/tpm/tpm-interface.c |  75 ++++++++++++++++
 drivers/char/tpm/tpm.h           |  14 +++
 drivers/char/tpm/tpm2-cmd.c      | 184 +++++++++++++++++++++++++++++++++++++++
 include/keys/trusted-type.h      |   2 +-
 include/linux/tpm.h              |  26 ++++++
 5 files changed, 300 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index e85d341..6dd4c74 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -666,6 +666,29 @@ int tpm_pcr_read_dev(struct tpm_chip *chip, int pcr_idx, u8 *res_buf)
 }
 
 /**
+ * tpm_is_tpm2 - is the chip a TPM2 chip?
+ * @chip_num:	tpm idx # or ANY
+ *
+ * Returns 1 if the chip is a TPM2 chip.
+ */
+int tpm_is_tpm2(u32 chip_num)
+{
+	struct tpm_chip *chip;
+	int rc;
+
+	chip = tpm_chip_find_get(chip_num);
+	if (chip == NULL)
+		return -ENODEV;
+
+	rc = (chip->flags & TPM_CHIP_FLAG_TPM2) != 0;
+
+	tpm_chip_put(chip);
+
+	return rc;
+}
+EXPORT_SYMBOL_GPL(tpm_is_tpm2);
+
+/**
  * tpm_pcr_read - read a pcr value
  * @chip_num:	tpm idx # or ANY
  * @pcr_idx:	pcr idx to retrieve
@@ -1021,6 +1044,58 @@ int tpm_get_random(u32 chip_num, u8 *out, size_t max)
 }
 EXPORT_SYMBOL_GPL(tpm_get_random);
 
+/**
+ * tpm_seal_trusted() - seal a trusted key
+ * @chip_num: A specific chip number for the request or TPM_ANY_NUM
+ * @options: authentication values and other options
+ * @payload: the key data in clear and encrypted form
+ *
+ * Returns < 0 on error and 0 on success. At the moment, only TPM 2.0 chips
+ * are supported.
+ */
+int tpm_seal_trusted(u32 chip_num, struct trusted_key_payload *payload,
+		     struct trusted_key_options *options)
+{
+	struct tpm_chip *chip;
+	int rc;
+
+	chip = tpm_chip_find_get(chip_num);
+	if (chip == NULL || !(chip->flags & TPM_CHIP_FLAG_TPM2))
+		return -ENODEV;
+
+	rc = tpm2_seal_trusted(chip, payload, options);
+
+	tpm_chip_put(chip);
+	return rc;
+}
+EXPORT_SYMBOL_GPL(tpm_seal_trusted);
+
+/**
+ * tpm_unseal_trusted() - unseal a trusted key
+ * @chip_num: A specific chip number for the request or TPM_ANY_NUM
+ * @options: authentication values and other options
+ * @payload: the key data in clear and encrypted form
+ *
+ * Returns < 0 on error and 0 on success. At the moment, only TPM 2.0 chips
+ * are supported.
+ */
+int tpm_unseal_trusted(u32 chip_num, struct trusted_key_payload *payload,
+		       struct trusted_key_options *options)
+{
+	struct tpm_chip *chip;
+	int rc;
+
+	chip = tpm_chip_find_get(chip_num);
+	if (chip == NULL || !(chip->flags & TPM_CHIP_FLAG_TPM2))
+		return -ENODEV;
+
+	rc = tpm2_unseal_trusted(chip, payload, options);
+
+	tpm_chip_put(chip);
+	return rc;
+}
+EXPORT_SYMBOL_GPL(tpm_unseal_trusted);
+
 static int __init tpm_init(void)
 {
 	int rc;
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index f04afb7..2d79939 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -88,6 +88,9 @@ enum tpm2_return_codes {
 
 enum tpm2_algorithms {
 	TPM2_ALG_SHA1		= 0x0004,
+	TPM2_ALG_KEYEDHASH	= 0x0008,
+	TPM2_ALG_SHA256		= 0x000B,
+	TPM2_ALG_NULL		= 0x0010
 };
 
 enum tpm2_command_codes {
@@ -95,6 +98,10 @@ enum tpm2_command_codes {
 	TPM2_CC_SELF_TEST	= 0x0143,
 	TPM2_CC_STARTUP		= 0x0144,
 	TPM2_CC_SHUTDOWN	= 0x0145,
+	TPM2_CC_CREATE		= 0x0153,
+	TPM2_CC_LOAD		= 0x0157,
+	TPM2_CC_UNSEAL		= 0x015E,
+	TPM2_CC_FLUSH_CONTEXT	= 0x0165,
 	TPM2_CC_GET_CAPABILITY	= 0x017A,
 	TPM2_CC_GET_RANDOM	= 0x017B,
 	TPM2_CC_PCR_READ	= 0x017E,
@@ -492,6 +499,13 @@ static inline void tpm_remove_ppi(struct tpm_chip *chip)
 int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx, u8 *res_buf);
 int tpm2_pcr_extend(struct tpm_chip *chip, int pcr_idx, const u8 *hash);
 int tpm2_get_random(struct tpm_chip *chip, u8 *out, size_t max);
+int tpm2_seal_trusted(struct tpm_chip *chip,
+		      struct trusted_key_payload *payload,
+		      struct trusted_key_options *options);
+int tpm2_unseal_trusted(struct tpm_chip *chip,
+			struct trusted_key_payload *payload,
+			struct trusted_key_options *options);
+
 ssize_t tpm2_get_tpm_pt(struct tpm_chip *chip, u32 property_id,
 			u32 *value, const char *desc);
 
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 0d55674..0986c96 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -16,6 +16,11 @@
  */
 
 #include "tpm.h"
+#include <keys/trusted-type.h>
+
+enum tpm2_object_attributes {
+	TPM2_ATTR_USER_WITH_AUTH	= BIT(6),
+};
 
 struct tpm2_pcr_read_in {
 	__be32	pcr_selects_cnt;
@@ -322,6 +327,185 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *res_buf, size_t max)
 }
 
 /**
+ * tpm2_seal_trusted() - seal a trusted key
+ * @chip_num: A specific chip number for the request or TPM_ANY_NUM
+ * @options: authentication values and other options
+ * @payload: the key data in clear and encrypted form
+ *
+ * Returns < 0 on error and 0 on success.
+ */
+int tpm2_seal_trusted(struct tpm_chip *chip,
+		      struct trusted_key_payload *payload,
+		      struct trusted_key_options *options)
+{
+	unsigned int blob_len;
+	struct tpm_buf buf;
+	int rc;
+
+	tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE);
+	tpm_buf_append_u32(&buf, options->keyhandle);
+	tpm2_buf_append_auth(&buf, TPM2_RS_PW,
+			     NULL /* nonce */, 0,
+			     0 /* session_attributes */,
+			     options->keyauth /* hmac */,
+			     TPM_DIGEST_SIZE);
+
+	/* sensitive */
+	tpm_buf_append_u16(&buf, 4 + TPM_DIGEST_SIZE + payload->key_len);
+
+	tpm_buf_append_u16(&buf, TPM_DIGEST_SIZE);
+	tpm_buf_append(&buf, options->blobauth, TPM_DIGEST_SIZE);
+	tpm_buf_append_u16(&buf, payload->key_len);
+	tpm_buf_append(&buf, payload->key, payload->key_len);
+
+	/* public */
+	tpm_buf_append_u16(&buf, 14);
+
+	tpm_buf_append_u16(&buf, TPM2_ALG_KEYEDHASH);
+	tpm_buf_append_u16(&buf, TPM2_ALG_SHA256);
+	tpm_buf_append_u32(&buf, TPM2_ATTR_USER_WITH_AUTH);
+	tpm_buf_append_u16(&buf, 0); /* policy digest size */
+	tpm_buf_append_u16(&buf, TPM2_ALG_NULL);
+	tpm_buf_append_u16(&buf, 0);
+
+	/* outside info */
+	tpm_buf_append_u16(&buf, 0);
+
+	/* creation PCR */
+	tpm_buf_append_u32(&buf, 0);
+
+	rc = tpm_transmit_cmd(chip, buf.data, TPM_BUF_SIZE, "sealing data");
+	if (rc)
+		goto out;
+
+	blob_len = be32_to_cpup((__be32 *) &buf.data[TPM_HEADER_SIZE]);
+	if (blob_len > MAX_BLOB_SIZE) {
+		rc = -E2BIG;
+		goto out;
+	}
+
+	memcpy(payload->blob, &buf.data[TPM_HEADER_SIZE + 4], blob_len);
+	payload->blob_len = blob_len;
+
+out:
+	if (rc > 0)
+		rc = -EPERM;
+
+	return rc;
+}
+
+static int tpm2_load(struct tpm_chip *chip,
+		     struct trusted_key_payload *payload,
+		     struct trusted_key_options *options,
+		     u32 *blob_handle)
+{
+	struct tpm_buf buf;
+	unsigned int private_len;
+	unsigned int public_len;
+	unsigned int blob_len;
+	int rc;
+
+	private_len = be16_to_cpup((__be16 *) &payload->blob[0]);
+	if (private_len > (payload->blob_len - 2))
+		return -E2BIG;
+
+	public_len = be16_to_cpup((__be16 *) &payload->blob[2 + private_len]);
+	blob_len = private_len + public_len + 4;
+	if (blob_len > payload->blob_len)
+		return -E2BIG;
+
+	tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_LOAD);
+	tpm_buf_append_u32(&buf, options->keyhandle);
+	tpm2_buf_append_auth(&buf, TPM2_RS_PW,
+			     NULL /* nonce */, 0,
+			     0 /* session_attributes */,
+			     options->keyauth /* hmac */,
+			     TPM_DIGEST_SIZE);
+
+	tpm_buf_append(&buf, payload->blob, payload->blob_len);
+
+	rc = tpm_transmit_cmd(chip, buf.data, TPM_BUF_SIZE, "loading blob");
+	if (!rc)
+		*blob_handle = be32_to_cpup(
+			(__be32 *) &buf.data[TPM_HEADER_SIZE]);
+
+	if (rc > 0)
+		rc = -EPERM;
+
+	return rc;
+}
+
+static void tpm2_flush_context(struct tpm_chip *chip, u32 handle)
+{
+	struct tpm_buf buf;
+	int rc;
+
+	tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_FLUSH_CONTEXT);
+	tpm_buf_append_u32(&buf, handle);
+
+	rc = tpm_transmit_cmd(chip, buf.data, TPM_BUF_SIZE, "flushing context");
+	if (rc)
+		dev_warn(chip->pdev, "0x%08x was not flushed\n", handle);
+}
+
+static int tpm2_unseal(struct tpm_chip *chip,
+		       struct trusted_key_payload *payload,
+		       struct trusted_key_options *options,
+		       u32 blob_handle)
+{
+	struct tpm_buf buf;
+	int rc;
+
+	tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_UNSEAL);
+	tpm_buf_append_u32(&buf, blob_handle);
+	tpm2_buf_append_auth(&buf, TPM2_RS_PW,
+			     NULL /* nonce */, 0,
+			     0 /* session_attributes */,
+			     options->blobauth /* hmac */,
+			     TPM_DIGEST_SIZE);
+
+	rc = tpm_transmit_cmd(chip, buf.data, TPM_BUF_SIZE, "unsealing");
+	if (rc > 0)
+		rc = -EPERM;
+
+	if (!rc) {
+		payload->key_len = be16_to_cpup(
+			(__be16 *) &buf.data[TPM_HEADER_SIZE + 4]);
+
+		memcpy(payload->key, &buf.data[TPM_HEADER_SIZE + 6],
+		       payload->key_len);
+	}
+
+	return rc;
+}
+
+/**
+ * tpm_unseal_trusted() - unseal a trusted key
+ * @chip_num: A specific chip number for the request or TPM_ANY_NUM
+ * @options: authentication values and other options
+ * @payload: the key data in clear and encrypted form
+ *
+ * Returns < 0 on error and 0 on success.
+ */
+int tpm2_unseal_trusted(struct tpm_chip *chip,
+			struct trusted_key_payload *payload,
+			struct trusted_key_options *options)
+{
+	u32 blob_handle;
+	int rc;
+
+	rc = tpm2_load(chip, payload, options, &blob_handle);
+	if (rc)
+		return rc;
+
+	rc = tpm2_unseal(chip, payload, options, blob_handle);
+
+	tpm2_flush_context(chip, blob_handle);
+
+	return rc;
+}
+
+/**
  * tpm2_get_tpm_pt() - get value of a TPM_CAP_TPM_PROPERTIES type property
  * @chip:		TPM chip to use.
  * @property_id:	property ID.
diff --git a/include/keys/trusted-type.h b/include/keys/trusted-type.h
index 9a2c626..0224b21 100644
--- a/include/keys/trusted-type.h
+++ b/include/keys/trusted-type.h
@@ -16,7 +16,7 @@
 
 #define MIN_KEY_SIZE			32
 #define MAX_KEY_SIZE			128
-#define MAX_BLOB_SIZE			320
+#define MAX_BLOB_SIZE			512
 #define MAX_PCRINFO_SIZE		64
 
 struct trusted_key_payload {
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 8350c53..706e63e 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -30,6 +30,8 @@
 #define	TPM_ANY_NUM 0xFFFF
 
 struct tpm_chip;
+struct trusted_key_payload;
+struct trusted_key_options;
 
 struct tpm_class_ops {
 	const u8 req_complete_mask;
@@ -46,11 +48,22 @@ struct tpm_class_ops {
 
 #if defined(CONFIG_TCG_TPM) || defined(CONFIG_TCG_TPM_MODULE)
 
+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_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,
+			    struct trusted_key_payload *payload,
+			    struct trusted_key_options *options);
+extern int tpm_unseal_trusted(u32 chip_num,
+			      struct trusted_key_payload *payload,
+			      struct trusted_key_options *options);
 #else
+static inline int tpm_is_tpm2(u32 chip_num)
+{
+	return -ENODEV;
+}
 static inline int tpm_pcr_read(u32 chip_num, int pcr_idx, u8 *res_buf) {
 	return -ENODEV;
 }
@@ -63,5 +76,18 @@ static inline int tpm_send(u32 chip_num, void *cmd, size_t buflen) {
 static inline int tpm_get_random(u32 chip_num, u8 *data, size_t max) {
 	return -ENODEV;
 }
+
+static inline int tpm_seal_trusted(u32 chip_num,
+				   struct trusted_key_payload *payload,
+				   struct trusted_key_options *options)
+{
+	return -ENODEV;
+}
+static inline int tpm_unseal_trusted(u32 chip_num,
+				     struct trusted_key_payload *payload,
+				     struct trusted_key_options *options)
+{
+	return -ENODEV;
+}
 #endif
 #endif
-- 
2.5.0

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