diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c
index 677c6e26593..36e43e50dce 100644
--- a/drivers/char/tpm/tpm.c
+++ b/drivers/char/tpm/tpm.c
@@ -32,12 +32,6 @@
 #include "tpm.h"
 #include "tpm_eventlog.h"
 
-enum tpm_const {
-	TPM_MINOR = 224,	/* officially assigned */
-	TPM_BUFSIZE = 4096,
-	TPM_NUM_DEVICES = 256,
-};
-
 enum tpm_duration {
 	TPM_SHORT = 0,
 	TPM_MEDIUM = 1,
@@ -483,6 +477,7 @@ static ssize_t transmit_cmd(struct tpm_chip *chip, struct tpm_cmd_t *cmd,
 #define TPM_INTERNAL_RESULT_SIZE 200
 #define TPM_TAG_RQU_COMMAND cpu_to_be16(193)
 #define TPM_ORD_GET_CAP cpu_to_be32(101)
+#define TPM_ORD_GET_RANDOM cpu_to_be32(70)
 
 static const struct tpm_input_header tpm_getcap_header = {
 	.tag = TPM_TAG_RQU_COMMAND,
@@ -1327,6 +1322,58 @@ int tpm_pm_resume(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(tpm_pm_resume);
 
+#define TPM_GETRANDOM_RESULT_SIZE	18
+static struct tpm_input_header tpm_getrandom_header = {
+	.tag = TPM_TAG_RQU_COMMAND,
+	.length = cpu_to_be32(14),
+	.ordinal = TPM_ORD_GET_RANDOM
+};
+
+/**
+ * tpm_get_random() - Get random bytes from the tpm's RNG
+ * @chip_num: A specific chip number for the request or TPM_ANY_NUM
+ * @out: destination buffer for the random bytes
+ * @max: the max number of bytes to write to @out
+ *
+ * Returns < 0 on error and the number of bytes read on success
+ */
+int tpm_get_random(u32 chip_num, u8 *out, size_t max)
+{
+	struct tpm_chip *chip;
+	struct tpm_cmd_t tpm_cmd;
+	u32 recd, num_bytes = min_t(u32, max, TPM_MAX_RNG_DATA);
+	int err, total = 0, retries = 5;
+	u8 *dest = out;
+
+	chip = tpm_chip_find_get(chip_num);
+	if (chip == NULL)
+		return -ENODEV;
+
+	if (!out || !num_bytes || max > TPM_MAX_RNG_DATA)
+		return -EINVAL;
+
+	do {
+		tpm_cmd.header.in = tpm_getrandom_header;
+		tpm_cmd.params.getrandom_in.num_bytes = cpu_to_be32(num_bytes);
+
+		err = transmit_cmd(chip, &tpm_cmd,
+				   TPM_GETRANDOM_RESULT_SIZE + num_bytes,
+				   "attempting get random");
+		if (err)
+			break;
+
+		recd = be32_to_cpu(tpm_cmd.params.getrandom_out.rng_data_len);
+		memcpy(dest, tpm_cmd.params.getrandom_out.rng_data, recd);
+
+		dest += recd;
+		total += recd;
+		num_bytes -= recd;
+	} while (retries-- && total < max);
+
+	return total ? total : -EIO;
+}
+EXPORT_SYMBOL_GPL(tpm_get_random);
+
 /* In case vendor provided release function, call it too.*/
 
 void tpm_dev_vendor_release(struct tpm_chip *chip)
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 917f727e674..645136eea89 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -28,6 +28,12 @@
 #include <linux/io.h>
 #include <linux/tpm.h>
 
+enum tpm_const {
+	TPM_MINOR = 224,	/* officially assigned */
+	TPM_BUFSIZE = 4096,
+	TPM_NUM_DEVICES = 256,
+};
+
 enum tpm_timeout {
 	TPM_TIMEOUT = 5,	/* msecs */
 };
@@ -269,6 +275,21 @@ struct tpm_pcrextend_in {
 	u8	hash[TPM_DIGEST_SIZE];
 }__attribute__((packed));
 
+/* 128 bytes is an arbitrary cap. This could be as large as TPM_BUFSIZE - 18
+ * bytes, but 128 is still a relatively large number of random bytes and
+ * anything much bigger causes users of struct tpm_cmd_t to start getting
+ * compiler warnings about stack frame size. */
+#define TPM_MAX_RNG_DATA	128
+
+struct tpm_getrandom_out {
+	__be32 rng_data_len;
+	u8     rng_data[TPM_MAX_RNG_DATA];
+}__attribute__((packed));
+
+struct tpm_getrandom_in {
+	__be32 num_bytes;
+}__attribute__((packed));
+
 typedef union {
 	struct	tpm_getcap_params_out getcap_out;
 	struct	tpm_readpubek_params_out readpubek_out;
@@ -277,6 +298,8 @@ typedef union {
 	struct	tpm_pcrread_in	pcrread_in;
 	struct	tpm_pcrread_out	pcrread_out;
 	struct	tpm_pcrextend_in pcrextend_in;
+	struct	tpm_getrandom_in getrandom_in;
+	struct	tpm_getrandom_out getrandom_out;
 } tpm_cmd_params;
 
 struct tpm_cmd_t {
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index fdc718abf83..fcb627ff8d3 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -32,6 +32,7 @@
 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);
 #else
 static inline int tpm_pcr_read(u32 chip_num, int pcr_idx, u8 *res_buf) {
 	return -ENODEV;
@@ -42,5 +43,8 @@ static inline int tpm_pcr_extend(u32 chip_num, int pcr_idx, const u8 *hash) {
 static inline int tpm_send(u32 chip_num, void *cmd, size_t buflen) {
 	return -ENODEV;
 }
+static inline int tpm_get_random(u32 chip_num, u8 *data, size_t max) {
+	return -ENODEV;
+}
 #endif
 #endif
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
@@ -368,38 +368,6 @@ static int trusted_tpm_send(const u32 chip_num, unsigned char *cmd,
 	return rc;
 }
 
-/*
- * 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.
  *
@@ -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;
 		}