1 files changed, 91 insertions, 63 deletions

diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c
index 511c67061728..b0f13c8ea79c 100644
--- a/drivers/char/tpm/tpm2-sessions.c
+++ b/drivers/char/tpm/tpm2-sessions.c
@@ -237,9 +237,7 @@ void tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf,
 #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++;
+		tpm_buf_append_handle(chip, buf, handle);
 		return;
 	}
 
@@ -272,6 +270,31 @@ void tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf,
 }
 EXPORT_SYMBOL_GPL(tpm_buf_append_name);
 
+void tpm_buf_append_auth(struct tpm_chip *chip, struct tpm_buf *buf,
+			 u8 attributes, u8 *passphrase, int passphrase_len)
+{
+	/* 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);
+}
+
 /**
  * tpm_buf_append_hmac_session() - Append a TPM session element
  * @chip: the TPM chip structure
@@ -309,30 +332,15 @@ void tpm_buf_append_hmac_session(struct tpm_chip *chip, struct tpm_buf *buf,
 #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);
+		tpm_buf_append_auth(chip, buf, attributes, passphrase,
+				    passphrase_len);
 		return;
 	}
 
 #ifdef CONFIG_TCG_TPM2_HMAC
+	/* The first write to /dev/tpm{rm0} will flush the session. */
+	attributes |= TPM2_SA_CONTINUE_SESSION;
+
 	/*
 	 * The Architecture Guide requires us to strip trailing zeros
 	 * before computing the HMAC
@@ -484,7 +492,8 @@ static void tpm2_KDFe(u8 z[EC_PT_SZ], const char *str, u8 *pt_u, u8 *pt_v,
 	sha256_final(&sctx, out);
 }
 
-static void tpm_buf_append_salt(struct tpm_buf *buf, struct tpm_chip *chip)
+static void tpm_buf_append_salt(struct tpm_buf *buf, struct tpm_chip *chip,
+				struct tpm2_auth *auth)
 {
 	struct crypto_kpp *kpp;
 	struct kpp_request *req;
@@ -543,7 +552,7 @@ static void tpm_buf_append_salt(struct tpm_buf *buf, struct tpm_chip *chip)
 	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);
+	sg_init_one(d, auth->salt, EC_PT_SZ);
 	kpp_request_set_output(req, d, EC_PT_SZ);
 	crypto_kpp_compute_shared_secret(req);
 	kpp_request_free(req);
@@ -554,8 +563,7 @@ static void tpm_buf_append_salt(struct tpm_buf *buf, struct tpm_chip *chip)
 	 * 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);
+	tpm2_KDFe(auth->salt, "SECRET", x, chip->null_ec_key_x, auth->salt);
 
  out:
 	crypto_free_kpp(kpp);
@@ -853,7 +861,9 @@ int tpm_buf_check_hmac_response(struct tpm_chip *chip, struct tpm_buf *buf,
 		if (rc)
 			/* manually close the session if it wasn't consumed */
 			tpm2_flush_context(chip, auth->handle);
-		memzero_explicit(auth, sizeof(*auth));
+
+		kfree_sensitive(auth);
+		chip->auth = NULL;
 	} else {
 		/* reset for next use  */
 		auth->session = TPM_HEADER_SIZE;
@@ -881,7 +891,8 @@ void tpm2_end_auth_session(struct tpm_chip *chip)
 		return;
 
 	tpm2_flush_context(chip, auth->handle);
-	memzero_explicit(auth, sizeof(*auth));
+	kfree_sensitive(auth);
+	chip->auth = NULL;
 }
 EXPORT_SYMBOL(tpm2_end_auth_session);
 
@@ -915,32 +926,39 @@ static int tpm2_parse_start_auth_session(struct tpm2_auth *auth,
 
 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];
+	u32 tmp_null_key;
+	int rc;
 
 	rc = tpm2_load_context(chip, chip->null_key_context, &offset,
-			       null_key);
-	if (rc != -EINVAL)
-		return rc;
+			       &tmp_null_key);
+	if (rc != -EINVAL) {
+		if (!rc)
+			*null_key = tmp_null_key;
+		goto err;
+	}
 
-	/* 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;
+	/* Try to re-create null key, given the integrity failure: */
+	rc = tpm2_create_primary(chip, TPM2_RH_NULL, &tmp_null_key, name);
+	if (rc)
+		goto err;
+
+	/* Return null key if the name has not been changed: */
+	if (!memcmp(name, chip->null_key_name, sizeof(name))) {
+		*null_key = tmp_null_key;
+		return 0;
+	}
+
+	/* Deduce from the name change TPM interference: */
+	dev_err(&chip->dev, "null key integrity check failed\n");
+	tpm2_flush_context(chip, tmp_null_key);
 
+err:
+	if (rc) {
+		chip->flags |= TPM_CHIP_FLAG_DISABLE;
+		rc = -ENODEV;
+	}
 	return rc;
 }
 
@@ -958,16 +976,20 @@ static int tpm2_load_null(struct tpm_chip *chip, u32 *null_key)
  */
 int tpm2_start_auth_session(struct tpm_chip *chip)
 {
+	struct tpm2_auth *auth;
 	struct tpm_buf buf;
-	struct tpm2_auth *auth = chip->auth;
-	int rc;
 	u32 null_key;
+	int rc;
 
-	if (!auth) {
-		dev_warn_once(&chip->dev, "auth session is not active\n");
+	if (chip->auth) {
+		dev_warn_once(&chip->dev, "auth session is active\n");
 		return 0;
 	}
 
+	auth = kzalloc(sizeof(*auth), GFP_KERNEL);
+	if (!auth)
+		return -ENOMEM;
+
 	rc = tpm2_load_null(chip, &null_key);
 	if (rc)
 		goto out;
@@ -988,7 +1010,7 @@ int tpm2_start_auth_session(struct tpm_chip *chip)
 	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);
+	tpm_buf_append_salt(&buf, chip, auth);
 	/* session type (HMAC, audit or policy) */
 	tpm_buf_append_u8(&buf, TPM2_SE_HMAC);
 
@@ -1010,10 +1032,13 @@ int tpm2_start_auth_session(struct tpm_chip *chip)
 
 	tpm_buf_destroy(&buf);
 
-	if (rc)
-		goto out;
+	if (rc == TPM2_RC_SUCCESS) {
+		chip->auth = auth;
+		return 0;
+	}
 
- out:
+out:
+	kfree_sensitive(auth);
 	return rc;
 }
 EXPORT_SYMBOL(tpm2_start_auth_session);
@@ -1347,18 +1372,21 @@ static int tpm2_create_null_primary(struct tpm_chip *chip)
  *
  * Derive and context save the null primary and allocate memory in the
  * struct tpm_chip for the authorizations.
+ *
+ * Return:
+ * * 0		- OK
+ * * -errno	- A system error
+ * * TPM_RC	- A TPM error
  */
 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;
+	if (rc) {
+		dev_err(&chip->dev, "null key creation failed with %d\n", rc);
+		return rc;
+	}
 
 	return rc;
 }