tpm: Move tpm_get_random api into the TPM device driver

Move the tpm_get_random api from the trusted keys code into the TPM
device driver itself so that other callers can make use of it. Also,
change the api slightly so that the number of bytes read is returned in
the call, since the TPM command can potentially return fewer bytes than
requested.

Acked-by: David Safford <safford@linux.vnet.ibm.com>
Reviewed-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Kent Yoder <key@linux.vnet.ibm.com>

1 files changed, 12 insertions, 42 deletions

diff --git a/security/keys/trusted.c b/security/keys/trusted.c
index 2d5d041f204..3f163d0489a 100644
--- a/security/keys/trusted.c
+++ b/security/keys/trusted.c
@@ -369,38 +369,6 @@ static int trusted_tpm_send(const u32 chip_num, unsigned char *cmd,
 }
 
 /*
- * get a random value from TPM
- */
-static int tpm_get_random(struct tpm_buf *tb, unsigned char *buf, uint32_t len)
-{
-	int ret;
-
-	INIT_BUF(tb);
-	store16(tb, TPM_TAG_RQU_COMMAND);
-	store32(tb, TPM_GETRANDOM_SIZE);
-	store32(tb, TPM_ORD_GETRANDOM);
-	store32(tb, len);
-	ret = trusted_tpm_send(TPM_ANY_NUM, tb->data, sizeof tb->data);
-	if (!ret)
-		memcpy(buf, tb->data + TPM_GETRANDOM_SIZE, len);
-	return ret;
-}
-
-static int my_get_random(unsigned char *buf, int len)
-{
-	struct tpm_buf *tb;
-	int ret;
-
-	tb = kmalloc(sizeof *tb, GFP_KERNEL);
-	if (!tb)
-		return -ENOMEM;
-	ret = tpm_get_random(tb, buf, len);
-
-	kfree(tb);
-	return ret;
-}
-
-/*
  * Lock a trusted key, by extending a selected PCR.
  *
  * Prevents a trusted key that is sealed to PCRs from being accessed.
@@ -413,8 +381,8 @@ static int pcrlock(const int pcrnum)
 
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
-	ret = my_get_random(hash, SHA1_DIGEST_SIZE);
-	if (ret < 0)
+	ret = tpm_get_random(TPM_ANY_NUM, hash, SHA1_DIGEST_SIZE);
+	if (ret != SHA1_DIGEST_SIZE)
 		return ret;
 	return tpm_pcr_extend(TPM_ANY_NUM, pcrnum, hash) ? -EINVAL : 0;
 }
@@ -429,8 +397,8 @@ static int osap(struct tpm_buf *tb, struct osapsess *s,
 	unsigned char ononce[TPM_NONCE_SIZE];
 	int ret;
 
-	ret = tpm_get_random(tb, ononce, TPM_NONCE_SIZE);
-	if (ret < 0)
+	ret = tpm_get_random(TPM_ANY_NUM, ononce, TPM_NONCE_SIZE);
+	if (ret != TPM_NONCE_SIZE)
 		return ret;
 
 	INIT_BUF(tb);
@@ -524,8 +492,8 @@ static int tpm_seal(struct tpm_buf *tb, uint16_t keytype,
 	if (ret < 0)
 		goto out;
 
-	ret = tpm_get_random(tb, td->nonceodd, TPM_NONCE_SIZE);
-	if (ret < 0)
+	ret = tpm_get_random(TPM_ANY_NUM, td->nonceodd, TPM_NONCE_SIZE);
+	if (ret != TPM_NONCE_SIZE)
 		goto out;
 	ordinal = htonl(TPM_ORD_SEAL);
 	datsize = htonl(datalen);
@@ -634,8 +602,8 @@ static int tpm_unseal(struct tpm_buf *tb,
 
 	ordinal = htonl(TPM_ORD_UNSEAL);
 	keyhndl = htonl(SRKHANDLE);
-	ret = tpm_get_random(tb, nonceodd, TPM_NONCE_SIZE);
-	if (ret < 0) {
+	ret = tpm_get_random(TPM_ANY_NUM, nonceodd, TPM_NONCE_SIZE);
+	if (ret != TPM_NONCE_SIZE) {
 		pr_info("trusted_key: tpm_get_random failed (%d)\n", ret);
 		return ret;
 	}
@@ -935,6 +903,7 @@ static int trusted_instantiate(struct key *key, const void *data,
 	char *datablob;
 	int ret = 0;
 	int key_cmd;
+	size_t key_len;
 
 	if (datalen <= 0 || datalen > 32767 || !data)
 		return -EINVAL;
@@ -974,8 +943,9 @@ static int trusted_instantiate(struct key *key, const void *data,
 			pr_info("trusted_key: key_unseal failed (%d)\n", ret);
 		break;
 	case Opt_new:
-		ret = my_get_random(payload->key, payload->key_len);
-		if (ret < 0) {
+		key_len = payload->key_len;
+		ret = tpm_get_random(TPM_ANY_NUM, payload->key, key_len);
+		if (ret != key_len) {
 			pr_info("trusted_key: key_create failed (%d)\n", ret);
 			goto out;
 		}