[PATCH RFC 5/5] keys: asymmetric: ASYMMETRIC_TPM2_KEY_RSA_SUBTYPE

Jarkko Sakkinen
2024-05-18T21:37:46Z

From: James Prestwood <prestwoj@gmail.com>

Based on earlier work by James Prestwood.

Add ASN.1 compatible asymmetric TPM2 RSA key subtype:

1. Signing and decryption (with the private key) is handled by TPM2_RSA_Decrypt.
2. Encryption (with the public key) is handled by the kernel RSA
implementation.

Link: https://lore.kernel.org/all/20200518172704.29608-1-prestwoj@gmail.com/
Signed-off-by: James Prestwood <prestwoj@gmail.com>
Co-developed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
crypto/asymmetric_keys/Kconfig | 12 +
crypto/asymmetric_keys/Makefile | 1 +
crypto/asymmetric_keys/tpm2_key_rsa.c | 648 ++++++++++++++++++++++++++
drivers/char/tpm/tpm2_key.c | 11 +
include/crypto/tpm2_key.h | 3 +
include/linux/tpm.h | 1 +
6 files changed, 676 insertions(+)
create mode 100644 crypto/asymmetric_keys/tpm2_key_rsa.c

diff --git a/crypto/asymmetric_keys/Kconfig b/crypto/asymmetric_keys/Kconfig
index e1345b8f39f1..0ccbc0e80aa2 100644
--- a/crypto/asymmetric_keys/Kconfig
+++ b/crypto/asymmetric_keys/Kconfig
@@ -23,6 +23,18 @@ config ASYMMETRIC_PUBLIC_KEY_SUBTYPE
appropriate hash algorithms (such as SHA-1) must be available.
ENOPKG will be reported if the requisite algorithm is unavailable.

+config ASYMMETRIC_TPM2_KEY_RSA_SUBTYPE
+ tristate "Asymmetric TPM2 RSA crypto algorithm subtype"
+ depends on TCG_TPM && TCG_TPM2_HAMC
+ select CRYPTO_RSA
+ select CRYPTO_SHA256
+ select CRYPTO_HASH_INFO
+ help
+ This option provides support for asymmetric TPM2 key type handling.
+ If signature generation and/or verification are to be used,
+ appropriate hash algorithms (such as SHA-256) must be available.
+ ENOPKG will be reported if the requisite algorithm is unavailable.
+
config X509_CERTIFICATE_PARSER
tristate "X.509 certificate parser"
depends on ASYMMETRIC_PUBLIC_KEY_SUBTYPE
diff --git a/crypto/asymmetric_keys/Makefile b/crypto/asymmetric_keys/Makefile
index bc65d3b98dcb..f9730b39f008 100644
--- a/crypto/asymmetric_keys/Makefile
+++ b/crypto/asymmetric_keys/Makefile
@@ -11,6 +11,7 @@ asymmetric_keys-y := \
signature.o

obj-$(CONFIG_ASYMMETRIC_PUBLIC_KEY_SUBTYPE) += public_key.o
+obj-$(CONFIG_ASYMMETRIC_TPM2_KEY_SUBTYPE) += tpm2_key_rsa.o

#
# X.509 Certificate handling
diff --git a/crypto/asymmetric_keys/tpm2_key_rsa.c b/crypto/asymmetric_keys/tpm2_key_rsa.c
new file mode 100644
index 000000000000..8f245dd1b8b0
--- /dev/null
+++ b/crypto/asymmetric_keys/tpm2_key_rsa.c
@@ -0,0 +1,648 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* TPM2 asymmetric public-key crypto subtype
+ *
+ * See Documentation/crypto/asymmetric-keys.rst
+ *
+ * Copyright (c) 2020 Intel Corporation
+ */
+
+#define pr_fmt(fmt) "tpm2_key: "fmt
+
+#include <asm/unaligned.h>
+#include <crypto/akcipher.h>
+#include <crypto/public_key.h>
+#include <crypto/rsa-pkcs1pad.h>
+#include <crypto/tpm2_key.h>
+#include <keys/asymmetric-subtype.h>
+#include <linux/keyctl.h>
+#include <linux/module.h>
+#include <linux/scatterlist.h>
+#include <linux/slab.h>
+#include <linux/tpm.h>
+
+/* Room to fit two u32 zeros for algo id and parameters length. */
+#define SETKEY_PARAMS_SIZE (sizeof(u32) * 2)
+
+/*
+ * Maximum buffer size for the BER/DER encoded public key. The public key
+ * is of the form SEQUENCE { INTEGER n, INTEGER e } where n is a maximum 2048
+ * bit key and e is usually 65537
+ * The encoding overhead is:
+ * - max 4 bytes for SEQUENCE
+ * - max 4 bytes for INTEGER n type/length
+ * - 257 bytes of n
+ * - max 2 bytes for INTEGER e type/length
+ * - 3 bytes of e
+ * - 4+4 of zeros for set_pub_key parameters (SETKEY_PARAMS_SIZE)
+ */
+#define PUB_KEY_BUF_SIZE (4 + 4 + 257 + 2 + 3 + SETKEY_PARAMS_SIZE)
+
+static int tpm2_rsa_decrypt(struct tpm_chip *chip, u32 parent,
+ const unsigned char *keyblob, size_t bloblen,
+ const void *data, size_t len, void *out)
+{
+ unsigned int private_len;
+ unsigned int public_len;
+ unsigned int parsed_len;
+ unsigned int offset = 0;
+ u32 blob_handle = 0;
+ u32 key_handle = 0;
+ struct tpm_buf buf;
+ u16 decrypted_len;
+ u8 *pos;
+ int ret;
+
+ private_len = be16_to_cpup((__be16 *)&keyblob[0]);
+ if (private_len > (bloblen - 2))
+ return -EINVAL;
+
+ public_len = be16_to_cpup((__be16 *)&keyblob[2 + private_len]);
+ parsed_len = private_len + public_len + 4;
+ if (parsed_len > bloblen)
+ return -EINVAL;
+
+ chip = tpm_find_get_ops(chip);
+ if (!chip)
+ return -ENODEV;
+
+ ret = tpm2_start_auth_session(chip);
+ if (ret)
+ goto err_ops;
+
+ if (parent == TPM2_RH_NULL) {
+ ret = tpm2_load_context(chip, chip->null_key_context, &offset,
+ &key_handle);
+ if (ret) {
+ ret = -EIO;
+ goto err_auth;
+ }
+ } else {
+ key_handle = parent;
+ }
+
+ ret = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_LOAD);
+ if (ret < 0)
+ goto err_key;
+
+ tpm_buf_append_name(chip, &buf, key_handle, NULL);
+ tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_CONTINUE_SESSION |
+ TPM2_SA_ENCRYPT, NULL, 0);
+ tpm_buf_append(&buf, keyblob, bloblen);
+
+ if (buf.flags & TPM_BUF_OVERFLOW) {
+ ret = -E2BIG;
+ goto err_buf;
+ }
+
+ tpm_buf_fill_hmac_session(chip, &buf);
+ ret = tpm_transmit_cmd(chip, &buf, 4, "loading blob");
+ ret = tpm_buf_check_hmac_response(chip, &buf, ret);
+ if (ret) {
+ ret = -EIO;
+ goto err_buf;
+ }
+
+ blob_handle = be32_to_cpup((__be32 *)&buf.data[TPM_HEADER_SIZE]);
+
+ tpm_buf_reset(&buf, TPM2_ST_SESSIONS, TPM2_CC_RSA_DECRYPT);
+
+ tpm_buf_append_name(chip, &buf, blob_handle, NULL);
+ tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_DECRYPT, NULL, 0);
+
+ tpm_buf_append_u16(&buf, len);
+ tpm_buf_append(&buf, data, len);
+ tpm_buf_append_u16(&buf, TPM_ALG_NULL);
+ tpm_buf_append_u16(&buf, 0);
+
+ tpm_buf_fill_hmac_session(chip, &buf);
+ ret = tpm_transmit_cmd(chip, &buf, 4, "decrypting RSA");
+ ret = tpm_buf_check_hmac_response(chip, &buf, ret);
+ if (ret) {
+ ret = -EIO;
+ goto err_blob;
+ }
+
+ pos = buf.data + TPM_HEADER_SIZE + 4;
+ decrypted_len = be16_to_cpup((__be16 *)pos);
+ pos += 2;
+
+ memcpy(out, pos, decrypted_len);
+ ret = decrypted_len;
+
+err_blob:
+ tpm2_flush_context(chip, blob_handle);
+
+err_buf:
+ tpm_buf_destroy(&buf);
+
+err_key:
+ tpm2_flush_context(chip, key_handle);
+
+err_auth:
+ if (ret < 0)
+ tpm2_end_auth_session(chip);
+
+err_ops:
+ tpm_put_ops(chip);
+ return ret;
+}
+
+/*
+ * PKCS1 padding (type 1)
+ */
+static int __maybe_unused tpm2_pad_pkcs1(const u8 *m, unsigned int mlen,
+ u8 *em, unsigned int em_len)
+{
+ unsigned int ps_len = em_len - mlen - 3;
+
+ if (mlen > em_len - 11)
+ return -EBADMSG;
+
+ em[0] = 0;
+ em[1] = 1;
+
+ memset(em + 2, 0xff, ps_len);
+
+ em[2 + ps_len] = 0;
+ memcpy(em + 2 + ps_len + 1, m, mlen);
+
+ return 0;
+}
+
+/*
+ * RFC 3447 - Section 7.2.2
+ */
+static const u8 *tpm2_unpad_pkcs1(const u8 *data, unsigned int len,
+ unsigned int *out_len)
+{
+ unsigned int i;
+
+ /*
+ * Size of input data should be checked against public key size by
+ * caller.
+ */
+ if (data[0] != 0 || data[1] != 2)
+ return NULL;
+
+ i = 2;
+
+ while (data[i] != 0 && i < len)
+ i++;
+
+ if (i == len)
+ return NULL;
+
+ *out_len = len - i - 1;
+
+ return data + i + 1;
+}
+
+/*
+ * Outputs the cipher algorithm name on success, and retuns -ENOPKG
+ * on failure.
+ */
+static int tpm2_key_get_akcipher(const char *encoding, const char *hash_algo,
+ char *cipher)
+{
+ ssize_t ret;
+
+ if (strcmp(encoding, "pkcs1") == 0) {
+ if (!hash_algo) {
+ strscpy(cipher, "pkcs1pad(rsa)");
+ return 0;
+ }
+
+ ret = snprintf(cipher, CRYPTO_MAX_ALG_NAME,
+ "pkcs1pad(rsa,%s)",
+ hash_algo);
+ if (ret >= CRYPTO_MAX_ALG_NAME)
+ return -ENOPKG;
+
+ return 0;
+ }
+
+ if (strcmp(encoding, "raw") == 0) {
+ strscpy(cipher, "rsa");
+ return 0;
+ }
+
+ return -ENOPKG;
+}
+
+static inline u8 *tpm2_key_append_tag(u8 *buf, u8 tag, u32 len)
+{
+ *buf++ = tag;
+
+ if (len <= 127) {
+ buf[0] = len;
+ return buf + 1;
+ }
+
+ if (len <= 255) {
+ buf[0] = 0x81;
+ buf[1] = len;
+ return buf + 2;
+ }
+
+ buf[0] = 0x82;
+ put_unaligned_be16(len, buf + 1);
+ return buf + 3;
+}
+
+static inline u32 tpm2_key_definite_length(u32 len)
+{
+ if (len <= 127)
+ return 1;
+ if (len <= 255)
+ return 2;
+ return 3;
+}
+
+static u32 tpm2_key_to_der(const void *pub_key, u32 len, u8 *buf)
+{
+ u8 *cur = buf;
+ u32 n_len = tpm2_key_definite_length(len) + 1 + len + 1;
+ u32 e_len = tpm2_key_definite_length(3) + 1 + 3;
+ u8 e[3] = { 0x01, 0x00, 0x01 };
+
+ /* SEQUENCE */
+ cur = tpm2_key_append_tag(cur, 0x30, n_len + e_len);
+ /* INTEGER n */
+ cur = tpm2_key_append_tag(cur, 0x02, len + 1);
+ cur[0] = 0x00;
+ memcpy(cur + 1, pub_key, len);
+ cur += len + 1;
+ cur = tpm2_key_append_tag(cur, 0x02, sizeof(e));
+ memcpy(cur, e, sizeof(e));
+ cur += sizeof(e);
+ /* Zero parameters to satisfy set_pub_key ABI. */
+ memset(cur, 0, SETKEY_PARAMS_SIZE);
+
+ return cur - buf;
+}
+
+/*
+ * Encryption operation is performed with the public key. Hence it is done
+ * in software
+ */
+static int tpm2_key_rsa_encrypt(struct tpm2_key *key,
+ struct kernel_pkey_params *params,
+ const void *in, void *out)
+{
+ char cipher[CRYPTO_MAX_ALG_NAME];
+ struct scatterlist in_sg, out_sg;
+ u8 der_pub_key[PUB_KEY_BUF_SIZE];
+ struct akcipher_request *req;
+ struct crypto_akcipher *tfm;
+ struct crypto_wait cwait;
+ u32 der_pub_key_len;
+ int rc;
+
+ rc = tpm2_key_get_akcipher(params->encoding, params->hash_algo, cipher);
+ if (rc < 0)
+ return rc;
+
+ tfm = crypto_alloc_akcipher(cipher, 0, 0);
+ if (IS_ERR(tfm))
+ return PTR_ERR(tfm);
+
+ der_pub_key_len = tpm2_key_to_der(key->pub, key->pub_len, der_pub_key);
+
+ rc = crypto_akcipher_set_pub_key(tfm, der_pub_key, der_pub_key_len);
+ if (rc < 0)
+ goto err_tfm;
+
+ req = akcipher_request_alloc(tfm, GFP_KERNEL);
+ if (!req) {
+ rc = -ENOMEM;
+ goto err_tfm;
+ }
+
+ sg_init_one(&in_sg, in, params->in_len);
+ sg_init_one(&out_sg, out, params->out_len);
+ akcipher_request_set_crypt(req, &in_sg, &out_sg, params->in_len,
+ params->out_len);
+
+ crypto_init_wait(&cwait);
+ akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
+ CRYPTO_TFM_REQ_MAY_SLEEP,
+ crypto_req_done, &cwait);
+
+ rc = crypto_akcipher_encrypt(req);
+ rc = crypto_wait_req(rc, &cwait);
+
+ if (!rc)
+ rc = req->dst_len;
+
+ akcipher_request_free(req);
+
+err_tfm:
+ crypto_free_akcipher(tfm);
+
+ return rc;
+}
+
+/*
+ * Decryption operation is performed with the private key in the TPM.
+ */
+static int tpm2_key_rsa_decrypt(struct tpm_chip *chip, struct tpm2_key *key,
+ size_t in_len, const void *in, void *out)
+{
+ unsigned int unpadded_len;
+ const u8 *unpadded;
+ u8 *decrypted;
+ int rc;
+
+ decrypted = kmalloc(key->pub_len, GFP_KERNEL);
+
+ rc = tpm2_rsa_decrypt(chip, key->parent, key->blob, key->blob_len, in,
+ in_len, decrypted);
+ if (rc < 0)
+ return rc;
+
+ unpadded = tpm2_unpad_pkcs1(decrypted, rc, &unpadded_len);
+ if (!unpadded)
+ return -EINVAL;
+
+ memcpy(out, unpadded, unpadded_len);
+ return unpadded_len;
+}
+
+/*
+ * Sign operation is an encryption using the TPM's private key. With RSA the
+ * only difference between encryption and decryption is where the padding goes.
+ * Since own padding can be used, TPM2_RSA_Decrypt can be repurposed to do
+ * encryption.
+ */
+static int tpm2_key_rsa_sign(struct tpm_chip *chip, struct tpm2_key *key,
+ struct kernel_pkey_params *params,
+ const void *in, void *out)
+{
+ const struct rsa_asn1_template *asn1;
+ u32 in_len = params->in_len;
+ void *asn1_wrapped = NULL;
+ u8 *padded;
+ int rc;
+
+ if (strcmp(params->encoding, "pkcs1")) {
+ rc = -ENOPKG;
+ goto done;
+ }
+
+ if (params->hash_algo) {
+ asn1 = rsa_lookup_asn1(params->hash_algo);
+ if (!asn1) {
+ rc = -ENOPKG;
+ goto done;
+ }
+
+ /* Request enough space for the ASN.1 template + input hash */
+ asn1_wrapped = kzalloc(in_len + asn1->size, GFP_KERNEL);
+ if (!asn1_wrapped) {
+ rc = -ENOMEM;
+ goto done;
+ }
+
+ /* Copy ASN.1 template, then the input */
+ memcpy(asn1_wrapped, asn1->data, asn1->size);
+ memcpy(asn1_wrapped + asn1->size, in, in_len);
+
+ in = asn1_wrapped;
+ in_len += asn1->size;
+ }
+
+ /*
+ * Using the TPM's decrypt call to sign (aka encrypt). This
+ * requires pre-padding the data with PKCS1.
+ */
+ padded = kmalloc(key->pub_len, GFP_KERNEL);
+ tpm2_pad_pkcs1(in, in_len, padded, key->pub_len);
+
+ rc = tpm2_rsa_decrypt(chip, key->parent, key->blob, key->blob_len,
+ padded, key->pub_len, out);
+
+ kfree(padded);
+done:
+ kfree(asn1_wrapped);
+ return rc;
+}
+
+static void tpm2_key_rsa_describe(const struct key *asymmetric_key,
+ struct seq_file *m)
+{
+ struct tpm2_key *key = asymmetric_key->payload.data[asym_crypto];
+
+ if (!key) {
+ pr_err("key is empty");
+ return;
+ }
+
+ seq_puts(m, "TPM2/RSA");
+}
+
+static void tpm2_key_rsa_destroy(void *payload0, void *payload3)
+{
+ struct tpm2_key *key = payload0;
+
+ if (!key)
+ return;
+
+ tpm2_key_destroy(key);
+}
+
+static int tpm2_key_rsa_eds_op(struct kernel_pkey_params *params,
+ const void *in, void *out)
+{
+ struct tpm2_key *tk = params->key->payload.data[asym_crypto];
+ struct tpm_chip *chip = tpm_default_chip();
+ int rc = -EOPNOTSUPP;
+
+ if (!chip)
+ return -ENODEV;
+
+ switch (params->op) {
+ case kernel_pkey_encrypt:
+ rc = tpm2_key_encrypt(tk, params, in, out);
+ break;
+ case kernel_pkey_decrypt:
+ rc = tpm2_key_decrypt(tk, chip, params, in, out);
+ break;
+ case kernel_pkey_sign:
+ rc = tpm2_key_sign(tk, chip, params, in, out);
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return rc;
+}
+
+static int tpm2_key_rsa_verify(const struct key *key,
+ const struct public_key_signature *sig)
+{
+ const struct tpm2_key *tk = key->payload.data[asym_crypto];
+ char alg_name[CRYPTO_MAX_ALG_NAME];
+ u8 der_pub_key[PUB_KEY_BUF_SIZE];
+ struct akcipher_request *req;
+ struct scatterlist src_sg[2];
+ struct crypto_akcipher *tfm;
+ struct crypto_wait cwait;
+ u32 der_pub_key_len;
+ int rc;
+
+ if (WARN_ON(!tk || !sig || !sig->s))
+ return -EINVAL;
+
+ if (!sig->digest)
+ return -ENOPKG;
+
+ rc = determine_akcipher(sig->encoding, sig->hash_algo, alg_name);
+ if (rc < 0)
+ return rc;
+
+ tfm = crypto_alloc_akcipher(alg_name, 0, 0);
+ if (IS_ERR(tfm))
+ return PTR_ERR(tfm);
+
+ der_pub_key_len = derive_pub_key(tk->pub, tk->pub_len,
+ der_pub_key);
+
+ rc = crypto_akcipher_set_pub_key(tfm, der_pub_key, der_pub_key_len);
+ if (rc < 0)
+ goto err_tfm;
+
+ rc = -ENOMEM;
+ req = akcipher_request_alloc(tfm, GFP_KERNEL);
+ if (!req)
+ goto err_tfm;
+
+ sg_init_table(src_sg, 2);
+ sg_set_buf(&src_sg[0], sig->s, sig->s_size);
+ sg_set_buf(&src_sg[1], sig->digest, sig->digest_size);
+ akcipher_request_set_crypt(req, src_sg, NULL, sig->s_size,
+ sig->digest_size);
+ crypto_init_wait(&cwait);
+ akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
+ CRYPTO_TFM_REQ_MAY_SLEEP,
+ crypto_req_done, &cwait);
+ rc = crypto_wait_req(crypto_akcipher_verify(req), &cwait);
+
+ akcipher_request_free(req);
+err_tfm:
+ crypto_free_akcipher(tfm);
+ pr_devel("<=%s() = %d\n", __func__, rc);
+ if (WARN_ON_ONCE(rc > 0))
+ rc = -EINVAL;
+ return rc;
+}
+
+static int tpm2_key_query(const struct kernel_pkey_params *params,
+ struct kernel_pkey_query *info)
+{
+ struct tpm2_key *tk = params->key->payload.data[asym_crypto];
+ char alg_name[CRYPTO_MAX_ALG_NAME];
+ u8 der_pub_key[PUB_KEY_BUF_SIZE];
+ struct crypto_akcipher *tfm;
+ u32 der_pub_key_len = 0;
+ unsigned int len;
+ int ret;
+
+ ret = determine_akcipher(params->encoding, params->hash_algo, alg_name);
+ if (ret < 0)
+ return ret;
+
+ tfm = crypto_alloc_akcipher(alg_name, 0, 0);
+ if (IS_ERR(tfm))
+ return PTR_ERR(tfm);
+
+ der_pub_key_len = derive_pub_key(tk->pub, tk->pub_len,
+ der_pub_key);
+
+ ret = crypto_akcipher_set_pub_key(tfm, der_pub_key, der_pub_key_len);
+ if (ret < 0)
+ goto err_tfm;
+
+ len = crypto_akcipher_maxsize(tfm);
+
+ info->key_size = tk->pub_len * 8;
+ info->max_data_size = tk->pub_len;
+ info->max_sig_size = len;
+ info->max_enc_size = len;
+ info->max_dec_size = tk->pub_len;
+
+ info->supported_ops = KEYCTL_SUPPORTS_ENCRYPT |
+ KEYCTL_SUPPORTS_DECRYPT |
+ KEYCTL_SUPPORTS_VERIFY |
+ KEYCTL_SUPPORTS_SIGN;
+
+err_tfm:
+ crypto_free_akcipher(tfm);
+ return ret;
+}
+
+/*
+ * Asymmetric TPM2 RSA key. Signs and decrypts with TPM.
+ */
+struct asymmetric_key_subtype tpm2_key_rsa_subtype = {
+ .owner = THIS_MODULE,
+ .name = "tpm2_key_rsa",
+ .name_len = sizeof("tpm2_key_rsa") - 1,
+ .describe = tpm2_key_rsa_describe,
+ .destroy = tpm2_key_rsa_destroy,
+ .query = tpm2_key_rsa_query,
+ .eds_op = tpm2_key_rsa_eds_op,
+ .verify_signature = tpm2_key_rsa_verify,
+};
+EXPORT_SYMBOL_GPL(tpm2_key_rsa_subtype);
+
+/*
+ * Attempt to parse a data blob for a key as a TPM private key blob.
+ */
+static int tpm2_key_preparse(struct key_preparsed_payload *prep)
+{
+ struct tpm2_key key;
+ int ret;
+
+ memset(&key, 0, sizeof(key));
+
+ /*
+ * TPM 2.0 RSA keys are recommended to be 2048 bits long. Assume the
+ * blob is no more than 4x that.
+ */
+ if (prep->datalen > 256 * 4)
+ return -EMSGSIZE;
+
+ ret = tpm2_key_decode(prep->data, prep->data_len, &key, MAX_BLOB_SIZE);
+ if (ret)
+ return ret;
+
+ prep->payload.data[asym_subtype] = &tpm2_key_rsa_subtype;
+ prep->payload.data[asym_key_ids] = NULL;
+ prep->payload.data[asym_crypto] = tk;
+ prep->payload.data[asym_auth] = NULL;
+ prep->quotalen = 100;
+
+ return 0;
+}
+
+static struct asymmetric_key_parser tpm2_key_rsa_parser = {
+ .owner = THIS_MODULE,
+ .name = "tpm2_key_rsa_parser",
+ .parse = tpm2_key_preparse,
+};
+
+static int __init tpm2_key_rsa_init(void)
+{
+ return register_asymmetric_key_parser(&tpm2_key_parser);
+}
+
+static void __exit tpm2_key_rsa_exit(void)
+{
+ unregister_asymmetric_key_parser(&tpm2_key_parser);
+}
+
+module_init(tpm2_key_rsa_init);
+module_exit(tpm2_key_rsa_exit);
+
+MODULE_DESCRIPTION("Asymmetric TPM2 RSA key");
+MODULE_LICENSE("GPL");
diff --git a/drivers/char/tpm/tpm2_key.c b/drivers/char/tpm/tpm2_key.c
index e09441efb0f0..0d125b53de0e 100644
--- a/drivers/char/tpm/tpm2_key.c
+++ b/drivers/char/tpm/tpm2_key.c
@@ -175,6 +175,17 @@ int tpm2_key_decode(const u8 *src, u32 src_len, struct tpm2_key *key,
return -ENOMEM;
}

+ ctx.blob_len = ctx.priv_len + ctx.pub_len;
+ ctx.blob = kmalloc(ctx.priv_len + ctx.pub_len, GFP_KERNEL);
+ if (!ctx.blob) {
+ kfree(ctx.pub);
+ kfree(ctx.priv);
+ return -ENOMEM;
+ }
+
+ memcpy((void *)ctx.blob, ctx.priv, ctx.priv_len);
+ memcpy((void *)ctx.blob + ctx.priv_len, ctx.pub, ctx.pub_len);
+
memcpy(key, &ctx, sizeof(ctx));
return 0;
}
diff --git a/include/crypto/tpm2_key.h b/include/crypto/tpm2_key.h
index e5d3330afef5..7b5c5ec6bed5 100644
--- a/include/crypto/tpm2_key.h
+++ b/include/crypto/tpm2_key.h
@@ -13,6 +13,8 @@ struct tpm2_key {
u32 pub_len;
const u8 *priv;
u32 priv_len;
+ const u8 *blob;
+ u32 blob_len;
};

int tpm2_key_encode(u8 *blob, u32 blob_auth_len, u32 key_handle, u8 *src);
@@ -27,6 +29,7 @@ static inline void tpm2_key_destroy(struct tpm2_key *key)
{
kfree(key->priv);
kfree(key->pub);
+ kfree(key->blob);
memset(key, 0, sizeof(*key));
}

diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 2f25ca07127b..238814ee5c6f 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -271,6 +271,7 @@ enum tpm2_command_codes {
TPM2_CC_NV_READ = 0x014E,
TPM2_CC_CREATE = 0x0153,
TPM2_CC_LOAD = 0x0157,
+ TPM2_CC_RSA_DECRYPT = 0x0159,
TPM2_CC_SEQUENCE_UPDATE = 0x015C,
TPM2_CC_UNSEAL = 0x015E,
TPM2_CC_CONTEXT_LOAD = 0x0161,
--
2.45.1