Merging upstream version 6.10.3.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1365 insertions, 0 deletions

diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c
new file mode 100644
index 0000000000..d3521aadd4
--- /dev/null
+++ b/drivers/char/tpm/tpm2-sessions.c
@@ -0,0 +1,1365 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Copyright (C) 2018 James.Bottomley@HansenPartnership.com
+ *
+ * Cryptographic helper routines for handling TPM2 sessions for
+ * authorization HMAC and request response encryption.
+ *
+ * The idea is to ensure that every TPM command is HMAC protected by a
+ * session, meaning in-flight tampering would be detected and in
+ * addition all sensitive inputs and responses should be encrypted.
+ *
+ * The basic way this works is to use a TPM feature called salted
+ * sessions where a random secret used in session construction is
+ * encrypted to the public part of a known TPM key.  The problem is we
+ * have no known keys, so initially a primary Elliptic Curve key is
+ * derived from the NULL seed (we use EC because most TPMs generate
+ * these keys much faster than RSA ones).  The curve used is NIST_P256
+ * because that's now mandated to be present in 'TCG TPM v2.0
+ * Provisioning Guidance'
+ *
+ * Threat problems: the initial TPM2_CreatePrimary is not (and cannot
+ * be) session protected, so a clever Man in the Middle could return a
+ * public key they control to this command and from there intercept
+ * and decode all subsequent session based transactions.  The kernel
+ * cannot mitigate this threat but, after boot, userspace can get
+ * proof this has not happened by asking the TPM to certify the NULL
+ * key.  This certification would chain back to the TPM Endorsement
+ * Certificate and prove the NULL seed primary had not been tampered
+ * with and thus all sessions must have been cryptographically secure.
+ * To assist with this, the initial NULL seed public key name is made
+ * available in a sysfs file.
+ *
+ * Use of these functions:
+ *
+ * The design is all the crypto, hash and hmac gunk is confined in this
+ * file and never needs to be seen even by the kernel internal user.  To
+ * the user there's an init function tpm2_sessions_init() that needs to
+ * be called once per TPM which generates the NULL seed primary key.
+ *
+ * These are the usage functions:
+ *
+ * tpm2_start_auth_session() which allocates the opaque auth structure
+ *	and gets a session from the TPM.  This must be called before
+ *	any of the following functions.  The session is protected by a
+ *	session_key which is derived from a random salt value
+ *	encrypted to the NULL seed.
+ * tpm2_end_auth_session() kills the session and frees the resources.
+ *	Under normal operation this function is done by
+ *	tpm_buf_check_hmac_response(), so this is only to be used on
+ *	error legs where the latter is not executed.
+ * tpm_buf_append_name() to add a handle to the buffer.  This must be
+ *	used in place of the usual tpm_buf_append_u32() for adding
+ *	handles because handles have to be processed specially when
+ *	calculating the HMAC.  In particular, for NV, volatile and
+ *	permanent objects you now need to provide the name.
+ * tpm_buf_append_hmac_session() which appends the hmac session to the
+ *	buf in the same way tpm_buf_append_auth does().
+ * tpm_buf_fill_hmac_session() This calculates the correct hash and
+ *	places it in the buffer.  It must be called after the complete
+ *	command buffer is finalized so it can fill in the correct HMAC
+ *	based on the parameters.
+ * tpm_buf_check_hmac_response() which checks the session response in
+ *	the buffer and calculates what it should be.  If there's a
+ *	mismatch it will log a warning and return an error.  If
+ *	tpm_buf_append_hmac_session() did not specify
+ *	TPM_SA_CONTINUE_SESSION then the session will be closed (if it
+ *	hasn't been consumed) and the auth structure freed.
+ */
+
+#include "tpm.h"
+#include <linux/random.h>
+#include <linux/scatterlist.h>
+#include <asm/unaligned.h>
+#include <crypto/kpp.h>
+#include <crypto/ecdh.h>
+#include <crypto/hash.h>
+#include <crypto/hmac.h>
+
+/* maximum number of names the TPM must remember for authorization */
+#define AUTH_MAX_NAMES	3
+
+#define AES_KEY_BYTES	AES_KEYSIZE_128
+#define AES_KEY_BITS	(AES_KEY_BYTES*8)
+
+/*
+ * This is the structure that carries all the auth information (like
+ * session handle, nonces, session key and auth) from use to use it is
+ * designed to be opaque to anything outside.
+ */
+struct tpm2_auth {
+	u32 handle;
+	/*
+	 * This has two meanings: before tpm_buf_fill_hmac_session()
+	 * it marks the offset in the buffer of the start of the
+	 * sessions (i.e. after all the handles).  Once the buffer has
+	 * been filled it markes the session number of our auth
+	 * session so we can find it again in the response buffer.
+	 *
+	 * The two cases are distinguished because the first offset
+	 * must always be greater than TPM_HEADER_SIZE and the second
+	 * must be less than or equal to 5.
+	 */
+	u32 session;
+	/*
+	 * the size here is variable and set by the size of our_nonce
+	 * which must be between 16 and the name hash length. we set
+	 * the maximum sha256 size for the greatest protection
+	 */
+	u8 our_nonce[SHA256_DIGEST_SIZE];
+	u8 tpm_nonce[SHA256_DIGEST_SIZE];
+	/*
+	 * the salt is only used across the session command/response
+	 * after that it can be used as a scratch area
+	 */
+	union {
+		u8 salt[EC_PT_SZ];
+		/* scratch for key + IV */
+		u8 scratch[AES_KEY_BYTES + AES_BLOCK_SIZE];
+	};
+	/*
+	 * the session key and passphrase are the same size as the
+	 * name digest (sha256 again).  The session key is constant
+	 * for the use of the session and the passphrase can change
+	 * with every invocation.
+	 *
+	 * Note: these fields must be adjacent and in this order
+	 * because several HMAC/KDF schemes use the combination of the
+	 * session_key and passphrase.
+	 */
+	u8 session_key[SHA256_DIGEST_SIZE];
+	u8 passphrase[SHA256_DIGEST_SIZE];
+	int passphrase_len;
+	struct crypto_aes_ctx aes_ctx;
+	/* saved session attributes: */
+	u8 attrs;
+	__be32 ordinal;
+
+	/*
+	 * memory for three authorization handles.  We know them by
+	 * handle, but they are part of the session by name, which
+	 * we must compute and remember
+	 */
+	u32 name_h[AUTH_MAX_NAMES];
+	u8 name[AUTH_MAX_NAMES][2 + SHA512_DIGEST_SIZE];
+};
+
+#ifdef CONFIG_TCG_TPM2_HMAC
+/*
+ * Name Size based on TPM algorithm (assumes no hash bigger than 255)
+ */
+static u8 name_size(const u8 *name)
+{
+	static u8 size_map[] = {
+		[TPM_ALG_SHA1] = SHA1_DIGEST_SIZE,
+		[TPM_ALG_SHA256] = SHA256_DIGEST_SIZE,
+		[TPM_ALG_SHA384] = SHA384_DIGEST_SIZE,
+		[TPM_ALG_SHA512] = SHA512_DIGEST_SIZE,
+	};
+	u16 alg = get_unaligned_be16(name);
+	return size_map[alg] + 2;
+}
+
+static int tpm2_parse_read_public(char *name, struct tpm_buf *buf)
+{
+	struct tpm_header *head = (struct tpm_header *)buf->data;
+	off_t offset = TPM_HEADER_SIZE;
+	u32 tot_len = be32_to_cpu(head->length);
+	u32 val;
+
+	/* we're starting after the header so adjust the length */
+	tot_len -= TPM_HEADER_SIZE;
+
+	/* skip public */
+	val = tpm_buf_read_u16(buf, &offset);
+	if (val > tot_len)
+		return -EINVAL;
+	offset += val;
+	/* name */
+	val = tpm_buf_read_u16(buf, &offset);
+	if (val != name_size(&buf->data[offset]))
+		return -EINVAL;
+	memcpy(name, &buf->data[offset], val);
+	/* forget the rest */
+	return 0;
+}
+
+static int tpm2_read_public(struct tpm_chip *chip, u32 handle, char *name)
+{
+	struct tpm_buf buf;
+	int rc;
+
+	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_READ_PUBLIC);
+	if (rc)
+		return rc;
+
+	tpm_buf_append_u32(&buf, handle);
+	rc = tpm_transmit_cmd(chip, &buf, 0, "read public");
+	if (rc == TPM2_RC_SUCCESS)
+		rc = tpm2_parse_read_public(name, &buf);
+
+	tpm_buf_destroy(&buf);
+
+	return rc;
+}
+#endif /* CONFIG_TCG_TPM2_HMAC */
+
+/**
+ * tpm_buf_append_name() - add a handle area to the buffer
+ * @chip: the TPM chip structure
+ * @buf: The buffer to be appended
+ * @handle: The handle to be appended
+ * @name: The name of the handle (may be NULL)
+ *
+ * In order to compute session HMACs, we need to know the names of the
+ * objects pointed to by the handles.  For most objects, this is simply
+ * the actual 4 byte handle or an empty buf (in these cases @name
+ * should be NULL) but for volatile objects, permanent objects and NV
+ * areas, the name is defined as the hash (according to the name
+ * algorithm which should be set to sha256) of the public area to
+ * which the two byte algorithm id has been appended.  For these
+ * objects, the @name pointer should point to this.  If a name is
+ * required but @name is NULL, then TPM2_ReadPublic() will be called
+ * on the handle to obtain the name.
+ *
+ * As with most tpm_buf operations, success is assumed because failure
+ * will be caused by an incorrect programming model and indicated by a
+ * kernel message.
+ */
+void tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf,
+			 u32 handle, u8 *name)
+{
+#ifdef CONFIG_TCG_TPM2_HMAC
+	enum tpm2_mso_type mso = tpm2_handle_mso(handle);
+	struct tpm2_auth *auth;
+	int slot;
+#endif
+
+	if (!tpm2_chip_auth(chip)) {
+		tpm_buf_append_u32(buf, handle);
+		/* count the number of handles in the upper bits of flags */
+		buf->handles++;
+		return;
+	}
+
+#ifdef CONFIG_TCG_TPM2_HMAC
+	slot = (tpm_buf_length(buf) - TPM_HEADER_SIZE) / 4;
+	if (slot >= AUTH_MAX_NAMES) {
+		dev_err(&chip->dev, "TPM: too many handles\n");
+		return;
+	}
+	auth = chip->auth;
+	WARN(auth->session != tpm_buf_length(buf),
+	     "name added in wrong place\n");
+	tpm_buf_append_u32(buf, handle);
+	auth->session += 4;
+
+	if (mso == TPM2_MSO_PERSISTENT ||
+	    mso == TPM2_MSO_VOLATILE ||
+	    mso == TPM2_MSO_NVRAM) {
+		if (!name)
+			tpm2_read_public(chip, handle, auth->name[slot]);
+	} else {
+		if (name)
+			dev_err(&chip->dev, "TPM: Handle does not require name but one is specified\n");
+	}
+
+	auth->name_h[slot] = handle;
+	if (name)
+		memcpy(auth->name[slot], name, name_size(name));
+#endif
+}
+EXPORT_SYMBOL_GPL(tpm_buf_append_name);
+
+/**
+ * tpm_buf_append_hmac_session() - Append a TPM session element
+ * @chip: the TPM chip structure
+ * @buf: The buffer to be appended
+ * @attributes: The session attributes
+ * @passphrase: The session authority (NULL if none)
+ * @passphrase_len: The length of the session authority (0 if none)
+ *
+ * This fills in a session structure in the TPM command buffer, except
+ * for the HMAC which cannot be computed until the command buffer is
+ * complete.  The type of session is controlled by the @attributes,
+ * the main ones of which are TPM2_SA_CONTINUE_SESSION which means the
+ * session won't terminate after tpm_buf_check_hmac_response(),
+ * TPM2_SA_DECRYPT which means this buffers first parameter should be
+ * encrypted with a session key and TPM2_SA_ENCRYPT, which means the
+ * response buffer's first parameter needs to be decrypted (confusing,
+ * but the defines are written from the point of view of the TPM).
+ *
+ * Any session appended by this command must be finalized by calling
+ * tpm_buf_fill_hmac_session() otherwise the HMAC will be incorrect
+ * and the TPM will reject the command.
+ *
+ * As with most tpm_buf operations, success is assumed because failure
+ * will be caused by an incorrect programming model and indicated by a
+ * kernel message.
+ */
+void tpm_buf_append_hmac_session(struct tpm_chip *chip, struct tpm_buf *buf,
+				 u8 attributes, u8 *passphrase,
+				 int passphrase_len)
+{
+#ifdef CONFIG_TCG_TPM2_HMAC
+	u8 nonce[SHA256_DIGEST_SIZE];
+	struct tpm2_auth *auth;
+	u32 len;
+#endif
+
+	if (!tpm2_chip_auth(chip)) {
+		/* offset tells us where the sessions area begins */
+		int offset = buf->handles * 4 + TPM_HEADER_SIZE;
+		u32 len = 9 + passphrase_len;
+
+		if (tpm_buf_length(buf) != offset) {
+			/* not the first session so update the existing length */
+			len += get_unaligned_be32(&buf->data[offset]);
+			put_unaligned_be32(len, &buf->data[offset]);
+		} else {
+			tpm_buf_append_u32(buf, len);
+		}
+		/* auth handle */
+		tpm_buf_append_u32(buf, TPM2_RS_PW);
+		/* nonce */
+		tpm_buf_append_u16(buf, 0);
+		/* attributes */
+		tpm_buf_append_u8(buf, 0);
+		/* passphrase */
+		tpm_buf_append_u16(buf, passphrase_len);
+		tpm_buf_append(buf, passphrase, passphrase_len);
+		return;
+	}
+
+#ifdef CONFIG_TCG_TPM2_HMAC
+	/*
+	 * The Architecture Guide requires us to strip trailing zeros
+	 * before computing the HMAC
+	 */
+	while (passphrase && passphrase_len > 0 && passphrase[passphrase_len - 1] == '\0')
+		passphrase_len--;
+
+	auth = chip->auth;
+	auth->attrs = attributes;
+	auth->passphrase_len = passphrase_len;
+	if (passphrase_len)
+		memcpy(auth->passphrase, passphrase, passphrase_len);
+
+	if (auth->session != tpm_buf_length(buf)) {
+		/* we're not the first session */
+		len = get_unaligned_be32(&buf->data[auth->session]);
+		if (4 + len + auth->session != tpm_buf_length(buf)) {
+			WARN(1, "session length mismatch, cannot append");
+			return;
+		}
+
+		/* add our new session */
+		len += 9 + 2 * SHA256_DIGEST_SIZE;
+		put_unaligned_be32(len, &buf->data[auth->session]);
+	} else {
+		tpm_buf_append_u32(buf, 9 + 2 * SHA256_DIGEST_SIZE);
+	}
+
+	/* random number for our nonce */
+	get_random_bytes(nonce, sizeof(nonce));
+	memcpy(auth->our_nonce, nonce, sizeof(nonce));
+	tpm_buf_append_u32(buf, auth->handle);
+	/* our new nonce */
+	tpm_buf_append_u16(buf, SHA256_DIGEST_SIZE);
+	tpm_buf_append(buf, nonce, SHA256_DIGEST_SIZE);
+	tpm_buf_append_u8(buf, auth->attrs);
+	/* and put a placeholder for the hmac */
+	tpm_buf_append_u16(buf, SHA256_DIGEST_SIZE);
+	tpm_buf_append(buf, nonce, SHA256_DIGEST_SIZE);
+#endif
+}
+EXPORT_SYMBOL_GPL(tpm_buf_append_hmac_session);
+
+#ifdef CONFIG_TCG_TPM2_HMAC
+
+static int tpm2_create_primary(struct tpm_chip *chip, u32 hierarchy,
+			       u32 *handle, u8 *name);
+
+/*
+ * It turns out the crypto hmac(sha256) is hard for us to consume
+ * because it assumes a fixed key and the TPM seems to change the key
+ * on every operation, so we weld the hmac init and final functions in
+ * here to give it the same usage characteristics as a regular hash
+ */
+static void tpm2_hmac_init(struct sha256_state *sctx, u8 *key, u32 key_len)
+{
+	u8 pad[SHA256_BLOCK_SIZE];
+	int i;
+
+	sha256_init(sctx);
+	for (i = 0; i < sizeof(pad); i++) {
+		if (i < key_len)
+			pad[i] = key[i];
+		else
+			pad[i] = 0;
+		pad[i] ^= HMAC_IPAD_VALUE;
+	}
+	sha256_update(sctx, pad, sizeof(pad));
+}
+
+static void tpm2_hmac_final(struct sha256_state *sctx, u8 *key, u32 key_len,
+			    u8 *out)
+{
+	u8 pad[SHA256_BLOCK_SIZE];
+	int i;
+
+	for (i = 0; i < sizeof(pad); i++) {
+		if (i < key_len)
+			pad[i] = key[i];
+		else
+			pad[i] = 0;
+		pad[i] ^= HMAC_OPAD_VALUE;
+	}
+
+	/* collect the final hash;  use out as temporary storage */
+	sha256_final(sctx, out);
+
+	sha256_init(sctx);
+	sha256_update(sctx, pad, sizeof(pad));
+	sha256_update(sctx, out, SHA256_DIGEST_SIZE);
+	sha256_final(sctx, out);
+}
+
+/*
+ * assume hash sha256 and nonces u, v of size SHA256_DIGEST_SIZE but
+ * otherwise standard tpm2_KDFa.  Note output is in bytes not bits.
+ */
+static void tpm2_KDFa(u8 *key, u32 key_len, const char *label, u8 *u,
+		      u8 *v, u32 bytes, u8 *out)
+{
+	u32 counter = 1;
+	const __be32 bits = cpu_to_be32(bytes * 8);
+
+	while (bytes > 0) {
+		struct sha256_state sctx;
+		__be32 c = cpu_to_be32(counter);
+
+		tpm2_hmac_init(&sctx, key, key_len);
+		sha256_update(&sctx, (u8 *)&c, sizeof(c));
+		sha256_update(&sctx, label, strlen(label)+1);
+		sha256_update(&sctx, u, SHA256_DIGEST_SIZE);
+		sha256_update(&sctx, v, SHA256_DIGEST_SIZE);
+		sha256_update(&sctx, (u8 *)&bits, sizeof(bits));
+		tpm2_hmac_final(&sctx, key, key_len, out);
+
+		bytes -= SHA256_DIGEST_SIZE;
+		counter++;
+		out += SHA256_DIGEST_SIZE;
+	}
+}
+
+/*
+ * Somewhat of a bastardization of the real KDFe.  We're assuming
+ * we're working with known point sizes for the input parameters and
+ * the hash algorithm is fixed at sha256.  Because we know that the
+ * point size is 32 bytes like the hash size, there's no need to loop
+ * in this KDF.
+ */
+static void tpm2_KDFe(u8 z[EC_PT_SZ], const char *str, u8 *pt_u, u8 *pt_v,
+		      u8 *out)
+{
+	struct sha256_state sctx;
+	/*
+	 * this should be an iterative counter, but because we know
+	 *  we're only taking 32 bytes for the point using a sha256
+	 *  hash which is also 32 bytes, there's only one loop
+	 */
+	__be32 c = cpu_to_be32(1);
+
+	sha256_init(&sctx);
+	/* counter (BE) */
+	sha256_update(&sctx, (u8 *)&c, sizeof(c));
+	/* secret value */
+	sha256_update(&sctx, z, EC_PT_SZ);
+	/* string including trailing zero */
+	sha256_update(&sctx, str, strlen(str)+1);
+	sha256_update(&sctx, pt_u, EC_PT_SZ);
+	sha256_update(&sctx, pt_v, EC_PT_SZ);
+	sha256_final(&sctx, out);
+}
+
+static void tpm_buf_append_salt(struct tpm_buf *buf, struct tpm_chip *chip)
+{
+	struct crypto_kpp *kpp;
+	struct kpp_request *req;
+	struct scatterlist s[2], d[1];
+	struct ecdh p = {0};
+	u8 encoded_key[EC_PT_SZ], *x, *y;
+	unsigned int buf_len;
+
+	/* secret is two sized points */
+	tpm_buf_append_u16(buf, (EC_PT_SZ + 2)*2);
+	/*
+	 * we cheat here and append uninitialized data to form
+	 * the points.  All we care about is getting the two
+	 * co-ordinate pointers, which will be used to overwrite
+	 * the uninitialized data
+	 */
+	tpm_buf_append_u16(buf, EC_PT_SZ);
+	x = &buf->data[tpm_buf_length(buf)];
+	tpm_buf_append(buf, encoded_key, EC_PT_SZ);
+	tpm_buf_append_u16(buf, EC_PT_SZ);
+	y = &buf->data[tpm_buf_length(buf)];
+	tpm_buf_append(buf, encoded_key, EC_PT_SZ);
+	sg_init_table(s, 2);
+	sg_set_buf(&s[0], x, EC_PT_SZ);
+	sg_set_buf(&s[1], y, EC_PT_SZ);
+
+	kpp = crypto_alloc_kpp("ecdh-nist-p256", CRYPTO_ALG_INTERNAL, 0);
+	if (IS_ERR(kpp)) {
+		dev_err(&chip->dev, "crypto ecdh allocation failed\n");
+		return;
+	}
+
+	buf_len = crypto_ecdh_key_len(&p);
+	if (sizeof(encoded_key) < buf_len) {
+		dev_err(&chip->dev, "salt buffer too small needs %d\n",
+			buf_len);
+		goto out;
+	}
+	crypto_ecdh_encode_key(encoded_key, buf_len, &p);
+	/* this generates a random private key */
+	crypto_kpp_set_secret(kpp, encoded_key, buf_len);
+
+	/* salt is now the public point of this private key */
+	req = kpp_request_alloc(kpp, GFP_KERNEL);
+	if (!req)
+		goto out;
+	kpp_request_set_input(req, NULL, 0);
+	kpp_request_set_output(req, s, EC_PT_SZ*2);
+	crypto_kpp_generate_public_key(req);
+	/*
+	 * we're not done: now we have to compute the shared secret
+	 * which is our private key multiplied by the tpm_key public
+	 * point, we actually only take the x point and discard the y
+	 * point and feed it through KDFe to get the final secret salt
+	 */
+	sg_set_buf(&s[0], chip->null_ec_key_x, EC_PT_SZ);
+	sg_set_buf(&s[1], chip->null_ec_key_y, EC_PT_SZ);
+	kpp_request_set_input(req, s, EC_PT_SZ*2);
+	sg_init_one(d, chip->auth->salt, EC_PT_SZ);
+	kpp_request_set_output(req, d, EC_PT_SZ);
+	crypto_kpp_compute_shared_secret(req);
+	kpp_request_free(req);
+
+	/*
+	 * pass the shared secret through KDFe for salt. Note salt
+	 * area is used both for input shared secret and output salt.
+	 * This works because KDFe fully consumes the secret before it
+	 * writes the salt
+	 */
+	tpm2_KDFe(chip->auth->salt, "SECRET", x, chip->null_ec_key_x,
+		  chip->auth->salt);
+
+ out:
+	crypto_free_kpp(kpp);
+}
+
+/**
+ * tpm_buf_fill_hmac_session() - finalize the session HMAC
+ * @chip: the TPM chip structure
+ * @buf: The buffer to be appended
+ *
+ * This command must not be called until all of the parameters have
+ * been appended to @buf otherwise the computed HMAC will be
+ * incorrect.
+ *
+ * This function computes and fills in the session HMAC using the
+ * session key and, if TPM2_SA_DECRYPT was specified, computes the
+ * encryption key and encrypts the first parameter of the command
+ * buffer with it.
+ *
+ * As with most tpm_buf operations, success is assumed because failure
+ * will be caused by an incorrect programming model and indicated by a
+ * kernel message.
+ */
+void tpm_buf_fill_hmac_session(struct tpm_chip *chip, struct tpm_buf *buf)
+{
+	u32 cc, handles, val;
+	struct tpm2_auth *auth = chip->auth;
+	int i;
+	struct tpm_header *head = (struct tpm_header *)buf->data;
+	off_t offset_s = TPM_HEADER_SIZE, offset_p;
+	u8 *hmac = NULL;
+	u32 attrs;
+	u8 cphash[SHA256_DIGEST_SIZE];
+	struct sha256_state sctx;
+
+	if (!auth)
+		return;
+
+	/* save the command code in BE format */
+	auth->ordinal = head->ordinal;
+
+	cc = be32_to_cpu(head->ordinal);
+
+	i = tpm2_find_cc(chip, cc);
+	if (i < 0) {
+		dev_err(&chip->dev, "Command 0x%x not found in TPM\n", cc);
+		return;
+	}
+	attrs = chip->cc_attrs_tbl[i];
+
+	handles = (attrs >> TPM2_CC_ATTR_CHANDLES) & GENMASK(2, 0);
+
+	/*
+	 * just check the names, it's easy to make mistakes.  This
+	 * would happen if someone added a handle via
+	 * tpm_buf_append_u32() instead of tpm_buf_append_name()
+	 */
+	for (i = 0; i < handles; i++) {
+		u32 handle = tpm_buf_read_u32(buf, &offset_s);
+
+		if (auth->name_h[i] != handle) {
+			dev_err(&chip->dev, "TPM: handle %d wrong for name\n",
+				  i);
+			return;
+		}
+	}
+	/* point offset_s to the start of the sessions */
+	val = tpm_buf_read_u32(buf, &offset_s);
+	/* point offset_p to the start of the parameters */
+	offset_p = offset_s + val;
+	for (i = 1; offset_s < offset_p; i++) {
+		u32 handle = tpm_buf_read_u32(buf, &offset_s);
+		u16 len;
+		u8 a;
+
+		/* nonce (already in auth) */
+		len = tpm_buf_read_u16(buf, &offset_s);
+		offset_s += len;
+
+		a = tpm_buf_read_u8(buf, &offset_s);
+
+		len = tpm_buf_read_u16(buf, &offset_s);
+		if (handle == auth->handle && auth->attrs == a) {
+			hmac = &buf->data[offset_s];
+			/*
+			 * save our session number so we know which
+			 * session in the response belongs to us
+			 */
+			auth->session = i;
+		}
+
+		offset_s += len;
+	}
+	if (offset_s != offset_p) {
+		dev_err(&chip->dev, "TPM session length is incorrect\n");
+		return;
+	}
+	if (!hmac) {
+		dev_err(&chip->dev, "TPM could not find HMAC session\n");
+		return;
+	}
+
+	/* encrypt before HMAC */
+	if (auth->attrs & TPM2_SA_DECRYPT) {
+		u16 len;
+
+		/* need key and IV */
+		tpm2_KDFa(auth->session_key, SHA256_DIGEST_SIZE
+			  + auth->passphrase_len, "CFB", auth->our_nonce,
+			  auth->tpm_nonce, AES_KEY_BYTES + AES_BLOCK_SIZE,
+			  auth->scratch);
+
+		len = tpm_buf_read_u16(buf, &offset_p);
+		aes_expandkey(&auth->aes_ctx, auth->scratch, AES_KEY_BYTES);
+		aescfb_encrypt(&auth->aes_ctx, &buf->data[offset_p],
+			       &buf->data[offset_p], len,
+			       auth->scratch + AES_KEY_BYTES);
+		/* reset p to beginning of parameters for HMAC */
+		offset_p -= 2;
+	}
+
+	sha256_init(&sctx);
+	/* ordinal is already BE */
+	sha256_update(&sctx, (u8 *)&head->ordinal, sizeof(head->ordinal));
+	/* add the handle names */
+	for (i = 0; i < handles; i++) {
+		enum tpm2_mso_type mso = tpm2_handle_mso(auth->name_h[i]);
+
+		if (mso == TPM2_MSO_PERSISTENT ||
+		    mso == TPM2_MSO_VOLATILE ||
+		    mso == TPM2_MSO_NVRAM) {
+			sha256_update(&sctx, auth->name[i],
+				      name_size(auth->name[i]));
+		} else {
+			__be32 h = cpu_to_be32(auth->name_h[i]);
+
+			sha256_update(&sctx, (u8 *)&h, 4);
+		}
+	}
+	if (offset_s != tpm_buf_length(buf))
+		sha256_update(&sctx, &buf->data[offset_s],
+			      tpm_buf_length(buf) - offset_s);
+	sha256_final(&sctx, cphash);
+
+	/* now calculate the hmac */
+	tpm2_hmac_init(&sctx, auth->session_key, sizeof(auth->session_key)
+		       + auth->passphrase_len);
+	sha256_update(&sctx, cphash, sizeof(cphash));
+	sha256_update(&sctx, auth->our_nonce, sizeof(auth->our_nonce));
+	sha256_update(&sctx, auth->tpm_nonce, sizeof(auth->tpm_nonce));
+	sha256_update(&sctx, &auth->attrs, 1);
+	tpm2_hmac_final(&sctx, auth->session_key, sizeof(auth->session_key)
+			+ auth->passphrase_len, hmac);
+}
+EXPORT_SYMBOL(tpm_buf_fill_hmac_session);
+
+/**
+ * tpm_buf_check_hmac_response() - check the TPM return HMAC for correctness
+ * @chip: the TPM chip structure
+ * @buf: the original command buffer (which now contains the response)
+ * @rc: the return code from tpm_transmit_cmd
+ *
+ * If @rc is non zero, @buf may not contain an actual return, so @rc
+ * is passed through as the return and the session cleaned up and
+ * de-allocated if required (this is required if
+ * TPM2_SA_CONTINUE_SESSION was not specified as a session flag).
+ *
+ * If @rc is zero, the response HMAC is computed against the returned
+ * @buf and matched to the TPM one in the session area.  If there is a
+ * mismatch, an error is logged and -EINVAL returned.
+ *
+ * The reason for this is that the command issue and HMAC check
+ * sequence should look like:
+ *
+ *	rc = tpm_transmit_cmd(...);
+ *	rc = tpm_buf_check_hmac_response(&buf, auth, rc);
+ *	if (rc)
+ *		...
+ *
+ * Which is easily layered into the current contrl flow.
+ *
+ * Returns: 0 on success or an error.
+ */
+int tpm_buf_check_hmac_response(struct tpm_chip *chip, struct tpm_buf *buf,
+				int rc)
+{
+	struct tpm_header *head = (struct tpm_header *)buf->data;
+	struct tpm2_auth *auth = chip->auth;
+	off_t offset_s, offset_p;
+	u8 rphash[SHA256_DIGEST_SIZE];
+	u32 attrs, cc;
+	struct sha256_state sctx;
+	u16 tag = be16_to_cpu(head->tag);
+	int parm_len, len, i, handles;
+
+	if (!auth)
+		return rc;
+
+	cc = be32_to_cpu(auth->ordinal);
+
+	if (auth->session >= TPM_HEADER_SIZE) {
+		WARN(1, "tpm session not filled correctly\n");
+		goto out;
+	}
+
+	if (rc != 0)
+		/* pass non success rc through and close the session */
+		goto out;
+
+	rc = -EINVAL;
+	if (tag != TPM2_ST_SESSIONS) {
+		dev_err(&chip->dev, "TPM: HMAC response check has no sessions tag\n");
+		goto out;
+	}
+
+	i = tpm2_find_cc(chip, cc);
+	if (i < 0)
+		goto out;
+	attrs = chip->cc_attrs_tbl[i];
+	handles = (attrs >> TPM2_CC_ATTR_RHANDLE) & 1;
+
+	/* point to area beyond handles */
+	offset_s = TPM_HEADER_SIZE + handles * 4;
+	parm_len = tpm_buf_read_u32(buf, &offset_s);
+	offset_p = offset_s;
+	offset_s += parm_len;
+	/* skip over any sessions before ours */
+	for (i = 0; i < auth->session - 1; i++) {
+		len = tpm_buf_read_u16(buf, &offset_s);
+		offset_s += len + 1;
+		len = tpm_buf_read_u16(buf, &offset_s);
+		offset_s += len;
+	}
+	/* TPM nonce */
+	len = tpm_buf_read_u16(buf, &offset_s);
+	if (offset_s + len > tpm_buf_length(buf))
+		goto out;
+	if (len != SHA256_DIGEST_SIZE)
+		goto out;
+	memcpy(auth->tpm_nonce, &buf->data[offset_s], len);
+	offset_s += len;
+	attrs = tpm_buf_read_u8(buf, &offset_s);
+	len = tpm_buf_read_u16(buf, &offset_s);
+	if (offset_s + len != tpm_buf_length(buf))
+		goto out;
+	if (len != SHA256_DIGEST_SIZE)
+		goto out;
+	/*
+	 * offset_s points to the HMAC. now calculate comparison, beginning
+	 * with rphash
+	 */
+	sha256_init(&sctx);
+	/* yes, I know this is now zero, but it's what the standard says */
+	sha256_update(&sctx, (u8 *)&head->return_code,
+		      sizeof(head->return_code));
+	/* ordinal is already BE */
+	sha256_update(&sctx, (u8 *)&auth->ordinal, sizeof(auth->ordinal));
+	sha256_update(&sctx, &buf->data[offset_p], parm_len);
+	sha256_final(&sctx, rphash);
+
+	/* now calculate the hmac */
+	tpm2_hmac_init(&sctx, auth->session_key, sizeof(auth->session_key)
+		       + auth->passphrase_len);
+	sha256_update(&sctx, rphash, sizeof(rphash));
+	sha256_update(&sctx, auth->tpm_nonce, sizeof(auth->tpm_nonce));
+	sha256_update(&sctx, auth->our_nonce, sizeof(auth->our_nonce));
+	sha256_update(&sctx, &auth->attrs, 1);
+	/* we're done with the rphash, so put our idea of the hmac there */
+	tpm2_hmac_final(&sctx, auth->session_key, sizeof(auth->session_key)
+			+ auth->passphrase_len, rphash);
+	if (memcmp(rphash, &buf->data[offset_s], SHA256_DIGEST_SIZE) == 0) {
+		rc = 0;
+	} else {
+		dev_err(&chip->dev, "TPM: HMAC check failed\n");
+		goto out;
+	}
+
+	/* now do response decryption */
+	if (auth->attrs & TPM2_SA_ENCRYPT) {
+		/* need key and IV */
+		tpm2_KDFa(auth->session_key, SHA256_DIGEST_SIZE
+			  + auth->passphrase_len, "CFB", auth->tpm_nonce,
+			  auth->our_nonce, AES_KEY_BYTES + AES_BLOCK_SIZE,
+			  auth->scratch);
+
+		len = tpm_buf_read_u16(buf, &offset_p);
+		aes_expandkey(&auth->aes_ctx, auth->scratch, AES_KEY_BYTES);
+		aescfb_decrypt(&auth->aes_ctx, &buf->data[offset_p],
+			       &buf->data[offset_p], len,
+			       auth->scratch + AES_KEY_BYTES);
+	}
+
+ out:
+	if ((auth->attrs & TPM2_SA_CONTINUE_SESSION) == 0) {
+		if (rc)
+			/* manually close the session if it wasn't consumed */
+			tpm2_flush_context(chip, auth->handle);
+		memzero_explicit(auth, sizeof(*auth));
+	} else {
+		/* reset for next use  */
+		auth->session = TPM_HEADER_SIZE;
+	}
+
+	return rc;
+}
+EXPORT_SYMBOL(tpm_buf_check_hmac_response);
+
+/**
+ * tpm2_end_auth_session() - kill the allocated auth session
+ * @chip: the TPM chip structure
+ *
+ * ends the session started by tpm2_start_auth_session and frees all
+ * the resources.  Under normal conditions,
+ * tpm_buf_check_hmac_response() will correctly end the session if
+ * required, so this function is only for use in error legs that will
+ * bypass the normal invocation of tpm_buf_check_hmac_response().
+ */
+void tpm2_end_auth_session(struct tpm_chip *chip)
+{
+	struct tpm2_auth *auth = chip->auth;
+
+	if (!auth)
+		return;
+
+	tpm2_flush_context(chip, auth->handle);
+	memzero_explicit(auth, sizeof(*auth));
+}
+EXPORT_SYMBOL(tpm2_end_auth_session);
+
+static int tpm2_parse_start_auth_session(struct tpm2_auth *auth,
+					 struct tpm_buf *buf)
+{
+	struct tpm_header *head = (struct tpm_header *)buf->data;
+	u32 tot_len = be32_to_cpu(head->length);
+	off_t offset = TPM_HEADER_SIZE;
+	u32 val;
+
+	/* we're starting after the header so adjust the length */
+	tot_len -= TPM_HEADER_SIZE;
+
+	/* should have handle plus nonce */
+	if (tot_len != 4 + 2 + sizeof(auth->tpm_nonce))
+		return -EINVAL;
+
+	auth->handle = tpm_buf_read_u32(buf, &offset);
+	val = tpm_buf_read_u16(buf, &offset);
+	if (val != sizeof(auth->tpm_nonce))
+		return -EINVAL;
+	memcpy(auth->tpm_nonce, &buf->data[offset], sizeof(auth->tpm_nonce));
+	/* now compute the session key from the nonces */
+	tpm2_KDFa(auth->salt, sizeof(auth->salt), "ATH", auth->tpm_nonce,
+		  auth->our_nonce, sizeof(auth->session_key),
+		  auth->session_key);
+
+	return 0;
+}
+
+static int tpm2_load_null(struct tpm_chip *chip, u32 *null_key)
+{
+	int rc;
+	unsigned int offset = 0; /* dummy offset for null seed context */
+	u8 name[SHA256_DIGEST_SIZE + 2];
+
+	rc = tpm2_load_context(chip, chip->null_key_context, &offset,
+			       null_key);
+	if (rc != -EINVAL)
+		return rc;
+
+	/* an integrity failure may mean the TPM has been reset */
+	dev_err(&chip->dev, "NULL key integrity failure!\n");
+	/* check the null name against what we know */
+	tpm2_create_primary(chip, TPM2_RH_NULL, NULL, name);
+	if (memcmp(name, chip->null_key_name, sizeof(name)) == 0)
+		/* name unchanged, assume transient integrity failure */
+		return rc;
+	/*
+	 * Fatal TPM failure: the NULL seed has actually changed, so
+	 * the TPM must have been illegally reset.  All in-kernel TPM
+	 * operations will fail because the NULL primary can't be
+	 * loaded to salt the sessions, but disable the TPM anyway so
+	 * userspace programmes can't be compromised by it.
+	 */
+	dev_err(&chip->dev, "NULL name has changed, disabling TPM due to interference\n");
+	chip->flags |= TPM_CHIP_FLAG_DISABLE;
+
+	return rc;
+}
+
+/**
+ * tpm2_start_auth_session() - create a HMAC authentication session with the TPM
+ * @chip: the TPM chip structure to create the session with
+ *
+ * This function loads the NULL seed from its saved context and starts
+ * an authentication session on the null seed, fills in the
+ * @chip->auth structure to contain all the session details necessary
+ * for performing the HMAC, encrypt and decrypt operations and
+ * returns.  The NULL seed is flushed before this function returns.
+ *
+ * Return: zero on success or actual error encountered.
+ */
+int tpm2_start_auth_session(struct tpm_chip *chip)
+{
+	struct tpm_buf buf;
+	struct tpm2_auth *auth = chip->auth;
+	int rc;
+	u32 null_key;
+
+	if (!auth) {
+		dev_warn_once(&chip->dev, "auth session is not active\n");
+		return 0;
+	}
+
+	rc = tpm2_load_null(chip, &null_key);
+	if (rc)
+		goto out;
+
+	auth->session = TPM_HEADER_SIZE;
+
+	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_START_AUTH_SESS);
+	if (rc)
+		goto out;
+
+	/* salt key handle */
+	tpm_buf_append_u32(&buf, null_key);
+	/* bind key handle */
+	tpm_buf_append_u32(&buf, TPM2_RH_NULL);
+	/* nonce caller */
+	get_random_bytes(auth->our_nonce, sizeof(auth->our_nonce));
+	tpm_buf_append_u16(&buf, sizeof(auth->our_nonce));
+	tpm_buf_append(&buf, auth->our_nonce, sizeof(auth->our_nonce));
+
+	/* append encrypted salt and squirrel away unencrypted in auth */
+	tpm_buf_append_salt(&buf, chip);
+	/* session type (HMAC, audit or policy) */
+	tpm_buf_append_u8(&buf, TPM2_SE_HMAC);
+
+	/* symmetric encryption parameters */
+	/* symmetric algorithm */
+	tpm_buf_append_u16(&buf, TPM_ALG_AES);
+	/* bits for symmetric algorithm */
+	tpm_buf_append_u16(&buf, AES_KEY_BITS);
+	/* symmetric algorithm mode (must be CFB) */
+	tpm_buf_append_u16(&buf, TPM_ALG_CFB);
+	/* hash algorithm for session */
+	tpm_buf_append_u16(&buf, TPM_ALG_SHA256);
+
+	rc = tpm_transmit_cmd(chip, &buf, 0, "start auth session");
+	tpm2_flush_context(chip, null_key);
+
+	if (rc == TPM2_RC_SUCCESS)
+		rc = tpm2_parse_start_auth_session(auth, &buf);
+
+	tpm_buf_destroy(&buf);
+
+	if (rc)
+		goto out;
+
+ out:
+	return rc;
+}
+EXPORT_SYMBOL(tpm2_start_auth_session);
+
+/*
+ * A mask containing the object attributes for the kernel held null primary key
+ * used in HMAC encryption. For more information on specific attributes look up
+ * to "8.3 TPMA_OBJECT (Object Attributes)".
+ */
+#define TPM2_OA_NULL_KEY ( \
+	TPM2_OA_NO_DA | \
+	TPM2_OA_FIXED_TPM | \
+	TPM2_OA_FIXED_PARENT | \
+	TPM2_OA_SENSITIVE_DATA_ORIGIN |	\
+	TPM2_OA_USER_WITH_AUTH | \
+	TPM2_OA_DECRYPT | \
+	TPM2_OA_RESTRICTED)
+
+/**
+ * tpm2_parse_create_primary() - parse the data returned from TPM_CC_CREATE_PRIMARY
+ *
+ * @chip:	The TPM the primary was created under
+ * @buf:	The response buffer from the chip
+ * @handle:	pointer to be filled in with the return handle of the primary
+ * @hierarchy:	The hierarchy the primary was created for
+ * @name:	pointer to be filled in with the primary key name
+ *
+ * Return:
+ * * 0		- OK
+ * * -errno	- A system error
+ * * TPM_RC	- A TPM error
+ */
+static int tpm2_parse_create_primary(struct tpm_chip *chip, struct tpm_buf *buf,
+				     u32 *handle, u32 hierarchy, u8 *name)
+{
+	struct tpm_header *head = (struct tpm_header *)buf->data;
+	off_t offset_r = TPM_HEADER_SIZE, offset_t;
+	u16 len = TPM_HEADER_SIZE;
+	u32 total_len = be32_to_cpu(head->length);
+	u32 val, param_len, keyhandle;
+
+	keyhandle = tpm_buf_read_u32(buf, &offset_r);
+	if (handle)
+		*handle = keyhandle;
+	else
+		tpm2_flush_context(chip, keyhandle);
+
+	param_len = tpm_buf_read_u32(buf, &offset_r);
+	/*
+	 * param_len doesn't include the header, but all the other
+	 * lengths and offsets do, so add it to parm len to make
+	 * the comparisons easier
+	 */
+	param_len += TPM_HEADER_SIZE;
+
+	if (param_len + 8 > total_len)
+		return -EINVAL;
+	len = tpm_buf_read_u16(buf, &offset_r);
+	offset_t = offset_r;
+	if (name) {
+		/*
+		 * now we have the public area, compute the name of
+		 * the object
+		 */
+		put_unaligned_be16(TPM_ALG_SHA256, name);
+		sha256(&buf->data[offset_r], len, name + 2);
+	}
+
+	/* validate the public key */
+	val = tpm_buf_read_u16(buf, &offset_t);
+
+	/* key type (must be what we asked for) */
+	if (val != TPM_ALG_ECC)
+		return -EINVAL;
+	val = tpm_buf_read_u16(buf, &offset_t);
+
+	/* name algorithm */
+	if (val != TPM_ALG_SHA256)
+		return -EINVAL;
+	val = tpm_buf_read_u32(buf, &offset_t);
+
+	/* object properties */
+	if (val != TPM2_OA_NULL_KEY)
+		return -EINVAL;
+
+	/* auth policy (empty) */
+	val = tpm_buf_read_u16(buf, &offset_t);
+	if (val != 0)
+		return -EINVAL;
+
+	/* symmetric key parameters */
+	val = tpm_buf_read_u16(buf, &offset_t);
+	if (val != TPM_ALG_AES)
+		return -EINVAL;
+
+	/* symmetric key length */
+	val = tpm_buf_read_u16(buf, &offset_t);
+	if (val != AES_KEY_BITS)
+		return -EINVAL;
+
+	/* symmetric encryption scheme */
+	val = tpm_buf_read_u16(buf, &offset_t);
+	if (val != TPM_ALG_CFB)
+		return -EINVAL;
+
+	/* signing scheme */
+	val = tpm_buf_read_u16(buf, &offset_t);
+	if (val != TPM_ALG_NULL)
+		return -EINVAL;
+
+	/* ECC Curve */
+	val = tpm_buf_read_u16(buf, &offset_t);
+	if (val != TPM2_ECC_NIST_P256)
+		return -EINVAL;
+
+	/* KDF Scheme */
+	val = tpm_buf_read_u16(buf, &offset_t);
+	if (val != TPM_ALG_NULL)
+		return -EINVAL;
+
+	/* extract public key (x and y points) */
+	val = tpm_buf_read_u16(buf, &offset_t);
+	if (val != EC_PT_SZ)
+		return -EINVAL;
+	memcpy(chip->null_ec_key_x, &buf->data[offset_t], val);
+	offset_t += val;
+	val = tpm_buf_read_u16(buf, &offset_t);
+	if (val != EC_PT_SZ)
+		return -EINVAL;
+	memcpy(chip->null_ec_key_y, &buf->data[offset_t], val);
+	offset_t += val;
+
+	/* original length of the whole TPM2B */
+	offset_r += len;
+
+	/* should have exactly consumed the TPM2B public structure */
+	if (offset_t != offset_r)
+		return -EINVAL;
+	if (offset_r > param_len)
+		return -EINVAL;
+
+	/* creation data (skip) */
+	len = tpm_buf_read_u16(buf, &offset_r);
+	offset_r += len;
+	if (offset_r > param_len)
+		return -EINVAL;
+
+	/* creation digest (must be sha256) */
+	len = tpm_buf_read_u16(buf, &offset_r);
+	offset_r += len;
+	if (len != SHA256_DIGEST_SIZE || offset_r > param_len)
+		return -EINVAL;
+
+	/* TPMT_TK_CREATION follows */
+	/* tag, must be TPM_ST_CREATION (0x8021) */
+	val = tpm_buf_read_u16(buf, &offset_r);
+	if (val != TPM2_ST_CREATION || offset_r > param_len)
+		return -EINVAL;
+
+	/* hierarchy */
+	val = tpm_buf_read_u32(buf, &offset_r);
+	if (val != hierarchy || offset_r > param_len)
+		return -EINVAL;
+
+	/* the ticket digest HMAC (might not be sha256) */
+	len = tpm_buf_read_u16(buf, &offset_r);
+	offset_r += len;
+	if (offset_r > param_len)
+		return -EINVAL;
+
+	/*
+	 * finally we have the name, which is a sha256 digest plus a 2
+	 * byte algorithm type
+	 */
+	len = tpm_buf_read_u16(buf, &offset_r);
+	if (offset_r + len != param_len + 8)
+		return -EINVAL;
+	if (len != SHA256_DIGEST_SIZE + 2)
+		return -EINVAL;
+
+	if (memcmp(chip->null_key_name, &buf->data[offset_r],
+		   SHA256_DIGEST_SIZE + 2) != 0) {
+		dev_err(&chip->dev, "NULL Seed name comparison failed\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/**
+ * tpm2_create_primary() - create a primary key using a fixed P-256 template
+ *
+ * @chip:      the TPM chip to create under
+ * @hierarchy: The hierarchy handle to create under
+ * @handle:    The returned volatile handle on success
+ * @name:      The name of the returned key
+ *
+ * For platforms that might not have a persistent primary, this can be
+ * used to create one quickly on the fly (it uses Elliptic Curve not
+ * RSA, so even slow TPMs can create one fast).  The template uses the
+ * TCG mandated H one for non-endorsement ECC primaries, i.e. P-256
+ * elliptic curve (the only current one all TPM2s are required to
+ * have) a sha256 name hash and no policy.
+ *
+ * Return:
+ * * 0		- OK
+ * * -errno	- A system error
+ * * TPM_RC	- A TPM error
+ */
+static int tpm2_create_primary(struct tpm_chip *chip, u32 hierarchy,
+			       u32 *handle, u8 *name)
+{
+	int rc;
+	struct tpm_buf buf;
+	struct tpm_buf template;
+
+	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE_PRIMARY);
+	if (rc)
+		return rc;
+
+	rc = tpm_buf_init_sized(&template);
+	if (rc) {
+		tpm_buf_destroy(&buf);
+		return rc;
+	}
+
+	/*
+	 * create the template.  Note: in order for userspace to
+	 * verify the security of the system, it will have to create
+	 * and certify this NULL primary, meaning all the template
+	 * parameters will have to be identical, so conform exactly to
+	 * the TCG TPM v2.0 Provisioning Guidance for the SRK ECC
+	 * key H template (H has zero size unique points)
+	 */
+
+	/* key type */
+	tpm_buf_append_u16(&template, TPM_ALG_ECC);
+
+	/* name algorithm */
+	tpm_buf_append_u16(&template, TPM_ALG_SHA256);
+
+	/* object properties */
+	tpm_buf_append_u32(&template, TPM2_OA_NULL_KEY);
+
+	/* sauth policy (empty) */
+	tpm_buf_append_u16(&template, 0);
+
+	/* BEGIN parameters: key specific; for ECC*/
+
+	/* symmetric algorithm */
+	tpm_buf_append_u16(&template, TPM_ALG_AES);
+
+	/* bits for symmetric algorithm */
+	tpm_buf_append_u16(&template, AES_KEY_BITS);
+
+	/* algorithm mode (must be CFB) */
+	tpm_buf_append_u16(&template, TPM_ALG_CFB);
+
+	/* scheme (NULL means any scheme) */
+	tpm_buf_append_u16(&template, TPM_ALG_NULL);
+
+	/* ECC Curve ID */
+	tpm_buf_append_u16(&template, TPM2_ECC_NIST_P256);
+
+	/* KDF Scheme */
+	tpm_buf_append_u16(&template, TPM_ALG_NULL);
+
+	/* unique: key specific; for ECC it is two zero size points */
+	tpm_buf_append_u16(&template, 0);
+	tpm_buf_append_u16(&template, 0);
+
+	/* END parameters */
+
+	/* primary handle */
+	tpm_buf_append_u32(&buf, hierarchy);
+	tpm_buf_append_empty_auth(&buf, TPM2_RS_PW);
+
+	/* sensitive create size is 4 for two empty buffers */
+	tpm_buf_append_u16(&buf, 4);
+
+	/* sensitive create auth data (empty) */
+	tpm_buf_append_u16(&buf, 0);
+
+	/* sensitive create sensitive data (empty) */
+	tpm_buf_append_u16(&buf, 0);
+
+	/* the public template */
+	tpm_buf_append(&buf, template.data, template.length);
+	tpm_buf_destroy(&template);
+
+	/* outside info (empty) */
+	tpm_buf_append_u16(&buf, 0);
+
+	/* creation PCR (none) */
+	tpm_buf_append_u32(&buf, 0);
+
+	rc = tpm_transmit_cmd(chip, &buf, 0,
+			      "attempting to create NULL primary");
+
+	if (rc == TPM2_RC_SUCCESS)
+		rc = tpm2_parse_create_primary(chip, &buf, handle, hierarchy,
+					       name);
+
+	tpm_buf_destroy(&buf);
+
+	return rc;
+}
+
+static int tpm2_create_null_primary(struct tpm_chip *chip)
+{
+	u32 null_key;
+	int rc;
+
+	rc = tpm2_create_primary(chip, TPM2_RH_NULL, &null_key,
+				 chip->null_key_name);
+
+	if (rc == TPM2_RC_SUCCESS) {
+		unsigned int offset = 0; /* dummy offset for null key context */
+
+		rc = tpm2_save_context(chip, null_key, chip->null_key_context,
+				       sizeof(chip->null_key_context), &offset);
+		tpm2_flush_context(chip, null_key);
+	}
+
+	return rc;
+}
+
+/**
+ * tpm2_sessions_init() - start of day initialization for the sessions code
+ * @chip: TPM chip
+ *
+ * Derive and context save the null primary and allocate memory in the
+ * struct tpm_chip for the authorizations.
+ */
+int tpm2_sessions_init(struct tpm_chip *chip)
+{
+	int rc;
+
+	rc = tpm2_create_null_primary(chip);
+	if (rc)
+		dev_err(&chip->dev, "TPM: security failed (NULL seed derivation): %d\n", rc);
+
+	chip->auth = kmalloc(sizeof(*chip->auth), GFP_KERNEL);
+	if (!chip->auth)
+		return -ENOMEM;
+
+	return rc;
+}
+#endif /* CONFIG_TCG_TPM2_HMAC */