KEYS: trusted: Add generic trusted keys framework

Current trusted keys framework is tightly coupled to use TPM device as
an underlying implementation which makes it difficult for implementations
like Trusted Execution Environment (TEE) etc. to provide trusted keys
support in case platform doesn't posses a TPM device.

Add a generic trusted keys framework where underlying implementations
can be easily plugged in. Create struct trusted_key_ops to achieve this,
which contains necessary functions of a backend.

Also, define a module parameter in order to select a particular trust
source in case a platform support multiple trust sources. In case its
not specified then implementation itetrates through trust sources list
starting with TPM and assign the first trust source as a backend which
has initiazed successfully during iteration.

Note that current implementation only supports a single trust source at
runtime which is either selectable at compile time or during boot via
aforementioned module parameter.

Suggested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

2 files changed, 61 insertions, 21 deletions

diff --git a/include/keys/trusted-type.h b/include/keys/trusted-type.h
index b2d87ad21714..d89fa2579ac0 100644
--- a/include/keys/trusted-type.h
+++ b/include/keys/trusted-type.h
@@ -11,6 +11,12 @@
 #include <linux/rcupdate.h>
 #include <linux/tpm.h>
 
+#ifdef pr_fmt
+#undef pr_fmt
+#endif
+
+#define pr_fmt(fmt) "trusted_key: " fmt
+
 #define MIN_KEY_SIZE			32
 #define MAX_KEY_SIZE			128
 #define MAX_BLOB_SIZE			512
@@ -42,6 +48,53 @@ struct trusted_key_options {
 	uint32_t policyhandle;
 };
 
+struct trusted_key_ops {
+	/*
+	 * flag to indicate if trusted key implementation supports migration
+	 * or not.
+	 */
+	unsigned char migratable;
+
+	/* Initialize key interface. */
+	int (*init)(void);
+
+	/* Seal a key. */
+	int (*seal)(struct trusted_key_payload *p, char *datablob);
+
+	/* Unseal a key. */
+	int (*unseal)(struct trusted_key_payload *p, char *datablob);
+
+	/* Get a randomized key. */
+	int (*get_random)(unsigned char *key, size_t key_len);
+
+	/* Exit key interface. */
+	void (*exit)(void);
+};
+
+struct trusted_key_source {
+	char *name;
+	struct trusted_key_ops *ops;
+};
+
 extern struct key_type key_type_trusted;
 
+#define TRUSTED_DEBUG 0
+
+#if TRUSTED_DEBUG
+static inline void dump_payload(struct trusted_key_payload *p)
+{
+	pr_info("key_len %d\n", p->key_len);
+	print_hex_dump(KERN_INFO, "key ", DUMP_PREFIX_NONE,
+		       16, 1, p->key, p->key_len, 0);
+	pr_info("bloblen %d\n", p->blob_len);
+	print_hex_dump(KERN_INFO, "blob ", DUMP_PREFIX_NONE,
+		       16, 1, p->blob, p->blob_len, 0);
+	pr_info("migratable %d\n", p->migratable);
+}
+#else
+static inline void dump_payload(struct trusted_key_payload *p)
+{
+}
+#endif
+
 #endif /* _KEYS_TRUSTED_TYPE_H */
diff --git a/include/keys/trusted_tpm.h b/include/keys/trusted_tpm.h
index a56d8e1298f2..7769b726863a 100644
--- a/include/keys/trusted_tpm.h
+++ b/include/keys/trusted_tpm.h
@@ -16,6 +16,8 @@
 #define LOAD32N(buffer, offset)	(*(uint32_t *)&buffer[offset])
 #define LOAD16(buffer, offset)	(ntohs(*(uint16_t *)&buffer[offset]))
 
+extern struct trusted_key_ops trusted_key_tpm_ops;
+
 struct osapsess {
 	uint32_t handle;
 	unsigned char secret[SHA1_DIGEST_SIZE];
@@ -52,30 +54,19 @@ int tpm2_unseal_trusted(struct tpm_chip *chip,
 #if TPM_DEBUG
 static inline void dump_options(struct trusted_key_options *o)
 {
-	pr_info("trusted_key: sealing key type %d\n", o->keytype);
-	pr_info("trusted_key: sealing key handle %0X\n", o->keyhandle);
-	pr_info("trusted_key: pcrlock %d\n", o->pcrlock);
-	pr_info("trusted_key: pcrinfo %d\n", o->pcrinfo_len);
+	pr_info("sealing key type %d\n", o->keytype);
+	pr_info("sealing key handle %0X\n", o->keyhandle);
+	pr_info("pcrlock %d\n", o->pcrlock);
+	pr_info("pcrinfo %d\n", o->pcrinfo_len);
 	print_hex_dump(KERN_INFO, "pcrinfo ", DUMP_PREFIX_NONE,
 		       16, 1, o->pcrinfo, o->pcrinfo_len, 0);
 }
 
-static inline void dump_payload(struct trusted_key_payload *p)
-{
-	pr_info("trusted_key: key_len %d\n", p->key_len);
-	print_hex_dump(KERN_INFO, "key ", DUMP_PREFIX_NONE,
-		       16, 1, p->key, p->key_len, 0);
-	pr_info("trusted_key: bloblen %d\n", p->blob_len);
-	print_hex_dump(KERN_INFO, "blob ", DUMP_PREFIX_NONE,
-		       16, 1, p->blob, p->blob_len, 0);
-	pr_info("trusted_key: migratable %d\n", p->migratable);
-}
-
 static inline void dump_sess(struct osapsess *s)
 {
 	print_hex_dump(KERN_INFO, "trusted-key: handle ", DUMP_PREFIX_NONE,
 		       16, 1, &s->handle, 4, 0);
-	pr_info("trusted-key: secret:\n");
+	pr_info("secret:\n");
 	print_hex_dump(KERN_INFO, "", DUMP_PREFIX_NONE,
 		       16, 1, &s->secret, SHA1_DIGEST_SIZE, 0);
 	pr_info("trusted-key: enonce:\n");
@@ -87,7 +78,7 @@ static inline void dump_tpm_buf(unsigned char *buf)
 {
 	int len;
 
-	pr_info("\ntrusted-key: tpm buffer\n");
+	pr_info("\ntpm buffer\n");
 	len = LOAD32(buf, TPM_SIZE_OFFSET);
 	print_hex_dump(KERN_INFO, "", DUMP_PREFIX_NONE, 16, 1, buf, len, 0);
 }
@@ -96,10 +87,6 @@ static inline void dump_options(struct trusted_key_options *o)
 {
 }
 
-static inline void dump_payload(struct trusted_key_payload *p)
-{
-}
-
 static inline void dump_sess(struct osapsess *s)
 {
 }