[PATCH v2 6/6] keys: asymmetric: ASYMMETRIC_TPM2_KEY_RSA_SUBTYPE

Jarkko Sakkinen
2024-05-21T03:17:27Z

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>
---
v2:
* Remove two spurios pr_info() messsages that I forgot to remove.
* Clean up padding functions and add additional checks for length
also in tpm2_unpad_pcks1().
* Add the missing success check kzalloc() in tpm2_key_rsa_decrypt().
* Check that params->out_len for capacity before copying the result.
---
crypto/asymmetric_keys/Kconfig | 16 +
crypto/asymmetric_keys/Makefile | 1 +
crypto/asymmetric_keys/tpm2_key_rsa.c | 698 ++++++++++++++++++++++++++
include/linux/tpm.h | 2 +
4 files changed, 717 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..4d14bb0c346e 100644
--- a/crypto/asymmetric_keys/Kconfig
+++ b/crypto/asymmetric_keys/Kconfig
@@ -15,6 +15,7 @@ config ASYMMETRIC_PUBLIC_KEY_SUBTYPE
select MPILIB
select CRYPTO_HASH_INFO
select CRYPTO_AKCIPHER
+ select CRYPTO_RSA
select CRYPTO_SIG
select CRYPTO_HASH
help
@@ -23,6 +24,21 @@ 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
+ select TCG_TPM2_HMAC
+ select CRYPTO_RSA
+ select CRYPTO_SHA256
+ select CRYPTO_HASH_INFO
+ select ASN1
+ select ASN1_ENCODER
+ 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..c6da84607824 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_RSA_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..32250ff38268
--- /dev/null
+++ b/crypto/asymmetric_keys/tpm2_key_rsa.c
@@ -0,0 +1,698 @@
+// 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
+ */
+
+#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-parser.h>
+#include <keys/asymmetric-subtype.h>
+#include <keys/trusted-type.h>
+#include <linux/asn1_encoder.h>
+#include <linux/keyctl.h>
+#include <linux/module.h>
+#include <linux/scatterlist.h>
+#include <linux/slab.h>
+#include <linux/tpm.h>
+
+#undef pr_fmt
+#define pr_fmt(fmt) "tpm2_key_rsa: "fmt
+
+#define PUB_KEY_BUF_SIZE 512
+
+struct tpm2_key_rsa {
+ struct tpm2_key key;
+ const u8 *pub;
+ int pub_len;
+};
+
+static const int PKCS1_PAD_MIN_SIZE = 11;
+
+/*
+ * Fill the data with PKCS#1 v1.5 padding.
+ */
+static int tpm2_pad_pkcs1(const u8 *in, int in_len, u8 *out, int out_len)
+{
+ unsigned int prefix_len = out_len - in_len - 3;
+
+ if (in_len > out_len - PKCS1_PAD_MIN_SIZE)
+ return -EBADMSG;
+
+ /* prefix */
+ out[0] = 0;
+ out[1] = 1;
+ memset(&out[2], 0xff, prefix_len);
+ out[2 + prefix_len] = 0;
+ /* payload */
+ memcpy(&out[2 + prefix_len + 1], in, in_len);
+
+ return 0;
+}
+
+/*
+ * RFC 3447 - Section 7.2.2
+ * Size of the input data should be checked against public key size by
+ * the caller.
+ */
+static const u8 *tpm2_unpad_pkcs1(const u8 *in, int in_len, int *out_len)
+{
+ int i;
+
+ if (in[0] != 0 || in[1] != 2)
+ return NULL;
+
+ i = 2;
+ while (in[i] != 0 && i < in_len)
+ i++;
+
+ if (i == in_len || i < (PKCS1_PAD_MIN_SIZE - 1))
+ return NULL;
+
+ *out_len = in_len - i - 1;
+ return in + 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) {
+ strcpy(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) {
+ strcpy(cipher, "rsa");
+ return 0;
+ }
+
+ return -ENOPKG;
+}
+
+static int tpm2_key_rsa_extract_pub(struct tpm2_key_rsa *key_rsa)
+{
+ struct tpm2_key *key = &key_rsa->key;
+ struct tpm_buf buf;
+ off_t offset = 2;
+ u16 policy_len;
+ u32 attr;
+ u16 bits;
+ u16 type;
+ u16 len;
+ u16 alg;
+ u32 exp;
+
+ buf.flags = TPM_BUF_TPM2B;
+ buf.length = key->pub_len;
+ buf.data = (void *)key->pub;
+
+ if (get_unaligned_be16(key->pub) != buf.length - 2)
+ return -EINVAL;
+
+ type = tpm_buf_read_u16(&buf, &offset);
+ pr_debug("pub type: 0x%04x\n", type);
+ if (type != TPM_ALG_RSA)
+ return -EINVAL;
+
+ alg = tpm_buf_read_u16(&buf, &offset);
+ pr_debug("pub name alg: 0x%04x\n", alg);
+ attr = tpm_buf_read_u32(&buf, &offset);
+ pr_debug("pub attributes: 0x%08x\n", attr);
+ policy_len = tpm_buf_read_u16(&buf, &offset);
+ pr_debug("pub policy length: %u bytes\n", policy_len);
+ offset += policy_len;
+
+ alg = tpm_buf_read_u16(&buf, &offset);
+ pr_debug("pub symmetric: 0x%04x\n", alg);
+ if (alg != TPM_ALG_NULL)
+ return -EINVAL;
+
+ alg = tpm_buf_read_u16(&buf, &offset);
+ pr_debug("pub symmetric scheme: 0x%04x\n", alg);
+ if (alg != TPM_ALG_NULL)
+ return -EINVAL;
+
+ bits = tpm_buf_read_u16(&buf, &offset);
+ pr_debug("pub bits: %u\n", bits);
+
+ exp = tpm_buf_read_u32(&buf, &offset);
+ pr_debug("pub exponent: 0x%08x\n", exp);
+ if (exp != 0x00000000 && exp != 0x00010001)
+ return -EINVAL;
+
+ len = tpm_buf_read_u16(&buf, &offset);
+ pr_debug("pub modulus: %u bytes\n", len);
+ key_rsa->pub = key->pub + offset;
+ key_rsa->pub_len = len;
+
+ return buf.flags & TPM_BUF_BOUNDARY_ERROR ? -EIO : 0;
+}
+
+static int tpm2_key_rsa_encode(const struct tpm2_key_rsa *key, u8 *buf)
+{
+ const int SCRATCH_SIZE = PAGE_SIZE;
+ const u8 exp[3] = {1, 0, 1};
+ u8 *scratch, *work, *work1, *end_work;
+ int pub_len = key->pub_len;
+ const u8 *pub = key->pub;
+ int ret;
+
+ scratch = kmalloc(SCRATCH_SIZE, GFP_KERNEL);
+ if (!scratch)
+ return -ENOMEM;
+
+ work = scratch;
+ end_work = &scratch[SCRATCH_SIZE];
+
+ work = asn1_encode_integer(work, end_work, pub, pub_len);
+ if (IS_ERR(work)) {
+ ret = PTR_ERR(work);
+ goto err;
+ }
+
+ work = asn1_encode_integer(work, end_work, exp, 3);
+ if (IS_ERR(work)) {
+ ret = PTR_ERR(work);
+ goto err;
+ }
+
+ work1 = buf;
+ work1 = asn1_encode_sequence(work1, &work1[PUB_KEY_BUF_SIZE],
+ scratch, work - scratch);
+ if (IS_ERR(work1)) {
+ ret = PTR_ERR(work1);
+ goto err;
+ }
+
+ memset(work1, 0, 8);
+
+ kfree(scratch);
+ return work1 - buf;
+
+err:
+ kfree(scratch);
+ return ret;
+}
+
+/*
+ * Encryption operation is performed with the public key. Hence it is done
+ * in software
+ */
+static int tpm2_key_rsa_encrypt(struct tpm2_key_rsa *key,
+ struct kernel_pkey_params *params,
+ const void *in, void *out)
+{
+ char cipher[CRYPTO_MAX_ALG_NAME];
+ struct scatterlist in_sg, out_sg;
+ u8 enc_pub_key[PUB_KEY_BUF_SIZE];
+ struct akcipher_request *req;
+ struct crypto_akcipher *tfm;
+ struct crypto_wait cwait;
+ 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);
+
+ rc = tpm2_key_rsa_encode(key, enc_pub_key);
+ if (rc < 0)
+ goto err_tfm;
+
+ rc = crypto_akcipher_set_pub_key(tfm, enc_pub_key, rc);
+ 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;
+}
+
+static int __tpm2_key_rsa_decrypt(struct tpm_chip *chip,
+ struct tpm2_key_rsa *key,
+ struct kernel_pkey_params *params,
+ const void *in, int in_len, void *out)
+{
+ unsigned int offset = 0;
+ u32 key_handle = 0;
+ struct tpm_buf buf;
+ u16 decrypted_len;
+ u32 parent;
+ u8 *pos;
+ int ret;
+
+ ret = tpm_try_get_ops(chip);
+ if (ret)
+ return ret;
+
+ ret = tpm2_start_auth_session(chip);
+ if (ret)
+ goto err_ops;
+
+ if (key->key.parent == TPM2_RH_NULL) {
+ ret = tpm2_load_context(chip, chip->null_key_context, &offset,
+ &parent);
+ if (ret) {
+ ret = -EIO;
+ goto err_auth;
+ }
+ } else {
+ parent = key->key.parent;
+ }
+
+ ret = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_LOAD);
+ if (ret < 0)
+ goto err_parent;
+
+ tpm_buf_append_name(chip, &buf, parent, NULL);
+ tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_CONTINUE_SESSION |
+ TPM2_SA_ENCRYPT, NULL, 0);
+ tpm_buf_append(&buf, key->key.blob, key->key.blob_len);
+ 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, "RSA key loading");
+ ret = tpm_buf_check_hmac_response(chip, &buf, ret);
+ if (ret) {
+ ret = -EIO;
+ goto err_buf;
+ }
+ key_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, key_handle, NULL);
+ tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_DECRYPT, NULL, 0);
+ tpm_buf_append_u16(&buf, in_len);
+ tpm_buf_append(&buf, in, in_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, "RSA key decrypting");
+ 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;
+
+ if (params->out_len < decrypted_len) {
+ ret = -EMSGSIZE;
+ goto err_blob;
+ }
+
+ memcpy(out, pos, decrypted_len);
+ ret = decrypted_len;
+
+err_blob:
+ tpm2_flush_context(chip, key_handle);
+
+err_buf:
+ tpm_buf_destroy(&buf);
+
+err_parent:
+ if (key->key.parent == TPM2_RH_NULL)
+ tpm2_flush_context(chip, parent);
+
+err_auth:
+ if (ret < 0)
+ tpm2_end_auth_session(chip);
+
+err_ops:
+ tpm_put_ops(chip);
+ return ret;
+}
+
+static int tpm2_key_rsa_decrypt(struct tpm_chip *chip, struct tpm2_key_rsa *key,
+ struct kernel_pkey_params *params,
+ const void *in, void *out)
+{
+ const u8 *ptr;
+ int out_len;
+ u8 *work;
+ int ret;
+
+ work = kzalloc(params->out_len, GFP_KERNEL);
+ if (!work)
+ return -ENOMEM;
+
+ ret = __tpm2_key_rsa_decrypt(chip, key, params, in, params->in_len,
+ work);
+ if (ret < 0)
+ goto err;
+
+ ptr = tpm2_unpad_pkcs1(work, ret, &out_len);
+ if (!ptr) {
+ ret = -EINVAL;
+ goto err;
+ }
+
+ if (out_len > params->out_len) {
+ ret = -EMSGSIZE;
+ goto err;
+ }
+
+ memcpy(out, ptr, out_len);
+ kfree(work);
+ return out_len;
+
+err:
+ kfree(work);
+ return ret;
+}
+
+/*
+ * 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_rsa *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;
+ int pub_len = key->pub_len;
+ u8 *padded;
+ int ret;
+
+ if (strcmp(params->encoding, "pkcs1") != 0) {
+ ret = -ENOPKG;
+ goto err;
+ }
+
+ if (params->hash_algo) {
+ asn1 = rsa_lookup_asn1(params->hash_algo);
+ if (!asn1) {
+ ret = -ENOPKG;
+ goto err;
+ }
+
+ /* Request enough space for the ASN.1 template + input hash */
+ asn1_wrapped = kzalloc(in_len + asn1->size, GFP_KERNEL);
+ if (!asn1_wrapped) {
+ ret = -ENOMEM;
+ goto err;
+ }
+
+ /* 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;
+ }
+
+ /* with padding: */
+ padded = kmalloc(pub_len, GFP_KERNEL);
+ tpm2_pad_pkcs1(in, in_len, padded, pub_len);
+ ret = __tpm2_key_rsa_decrypt(chip, key, params, padded, pub_len, out);
+ kfree(padded);
+
+err:
+ kfree(asn1_wrapped);
+ return ret;
+}
+
+static void tpm2_key_rsa_describe(const struct key *asymmetric_key,
+ struct seq_file *m)
+{
+ struct tpm2_key_rsa *key = asymmetric_key->payload.data[asym_crypto];
+
+ if (!key) {
+ pr_err("key blob missing");
+ 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);
+ kfree(key);
+}
+
+static int tpm2_key_rsa_eds_op(struct kernel_pkey_params *params,
+ const void *in, void *out)
+{
+ struct tpm2_key_rsa *key = params->key->payload.data[asym_crypto];
+ struct tpm_chip *chip = tpm_default_chip();
+
+ if (!chip)
+ return -ENODEV;
+
+ switch (params->op) {
+ case kernel_pkey_encrypt:
+ return tpm2_key_rsa_encrypt(key, params, in, out);
+ case kernel_pkey_decrypt:
+ return tpm2_key_rsa_decrypt(chip, key, params, in, out);
+ case kernel_pkey_sign:
+ return tpm2_key_rsa_sign(chip, key, params, in, out);
+ default:
+ return -EOPNOTSUPP;
+ }
+}
+
+static int tpm2_key_rsa_verify(const struct key *key,
+ const struct public_key_signature *sig)
+{
+ const struct tpm2_key_rsa *tpm2_key = key->payload.data[asym_crypto];
+ char alg_name[CRYPTO_MAX_ALG_NAME];
+ u8 enc_pub_key[PUB_KEY_BUF_SIZE];
+ struct akcipher_request *req;
+ struct scatterlist src_sg[2];
+ struct crypto_akcipher *tfm;
+ struct crypto_wait cwait;
+ int rc;
+
+ if (!sig->digest)
+ return -ENOPKG;
+
+ rc = tpm2_key_get_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);
+
+ rc = tpm2_key_rsa_encode(tpm2_key, enc_pub_key);
+ if (rc < 0)
+ goto err_tfm;
+
+ rc = crypto_akcipher_set_pub_key(tfm, enc_pub_key, rc);
+ 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);
+ return rc;
+}
+
+static int tpm2_key_rsa_query(const struct kernel_pkey_params *params,
+ struct kernel_pkey_query *info)
+{
+ struct tpm2_key_rsa *tk = params->key->payload.data[asym_crypto];
+ char alg_name[CRYPTO_MAX_ALG_NAME];
+ u8 enc_pub_key[PUB_KEY_BUF_SIZE];
+ struct crypto_akcipher *tfm;
+ unsigned int len;
+ int ret;
+
+ ret = tpm2_key_get_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);
+
+ ret = tpm2_key_rsa_encode(tk, enc_pub_key);
+ if (ret < 0)
+ goto err_tfm;
+
+ ret = crypto_akcipher_set_pub_key(tfm, enc_pub_key, ret);
+ 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_rsa *key;
+ int ret;
+
+ key = kzalloc(sizeof(*key), GFP_KERNEL);
+ if (!key)
+ return -ENOMEM;
+
+ /*
+ * 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) {
+ kfree(key);
+ return -EMSGSIZE;
+ }
+
+ ret = tpm2_key_decode(prep->data, prep->datalen, &key->key, PAGE_SIZE);
+ if (ret) {
+ kfree(key);
+ return ret;
+ }
+
+ if (key->key.oid != OID_TPMLoadableKey) {
+ tpm2_key_destroy(&key->key);
+ kfree(key);
+ return -EINVAL;
+ }
+
+ ret = tpm2_key_rsa_extract_pub(key);
+ if (ret < 0) {
+ tpm2_key_destroy(&key->key);
+ kfree(key);
+ return ret;
+ }
+
+ prep->payload.data[asym_subtype] = &tpm2_key_rsa_subtype;
+ prep->payload.data[asym_key_ids] = NULL;
+ prep->payload.data[asym_crypto] = key;
+ 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_rsa_parser);
+}
+
+static void __exit tpm2_key_rsa_exit(void)
+{
+ unregister_asymmetric_key_parser(&tpm2_key_rsa_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/include/linux/tpm.h b/include/linux/tpm.h
index 2f25ca07127b..8161758da19a 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -43,6 +43,7 @@ enum tpm2_session_types {
/* if you add a new hash to this, increment TPM_MAX_HASHES below */
enum tpm_algorithms {
TPM_ALG_ERROR = 0x0000,
+ TPM_ALG_RSA = 0x0001,
TPM_ALG_SHA1 = 0x0004,
TPM_ALG_AES = 0x0006,
TPM_ALG_KEYEDHASH = 0x0008,
@@ -271,6 +272,7 @@ 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