Re: [PATCH v7 4/5] keys: asymmetric: Add tpm2_key_rsa

Stefan Berger
2024-05-31T01:10:54Z

On 5/28/24 17:08, Jarkko Sakkinen wrote:
> * Asymmetric TPM2 RSA key with signing and verification.
> * Encryption and decryption when pcks1 encoding is used.
> * Enabled with CONFIG_ASYMMETRIC_TPM2_KEY_ECDSA_SUBTYPE.

s/ECDSA/RSA !

>
> Signed-off-by: James Prestwood <prestwoj@gmail.com>
> Co-developed-by: Jarkko Sakkinen <jarkko@kernel.org>
> Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
> ---
> v6:
> * Validate RSA parameters, and also that the blob has space for
> them.
> * Fix tpm2_key_rsa_destroy() memory corruption: cast to tpm2_key_rsa
> * Allocate temporary buffers from heap.
> * Rename tpm2_key_rsa_extract_pub to tpm2_key_rsa_probe.
> * While pre-parsing, return -EBADMSG when the probing fails. This
> translates to "not detected" for the framework, i.e. should not
> be considered as an error but instead "move on". E.g. TPM_ALG_RSA
> is checked and if it is instead TPM_ALG_ECDSA, then it is passed
> to that module.
> v5:
> * akcipher has two *undocumented* parameters. Document this clearly.
> * Remove unused variable.
> v4:
> * Just put the values to the buffer instead of encoding them.
> * Adjust buffer sizes.
> * Make tpm2_rsa_key_encode() not to allocate from heap and simplify
> the serialization.
> v3:
> * Drop the special case for null handle i.e. do not define policy.
> * Remove extra empty line.
> 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 | 15 +
> crypto/asymmetric_keys/Makefile | 1 +
> crypto/asymmetric_keys/tpm2_key_rsa.c | 678 ++++++++++++++++++++++++++
> include/linux/tpm.h | 2 +
> 4 files changed, 696 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..9d88c1190621 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 +24,20 @@ 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 CRYPTO_RSA
> + select CRYPTO_SHA256
> + select CRYPTO_HASH_INFO
> + select CRYPTO_TPM2_KEY
> + select ASN1
> + 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.
> +

s/requisite/required ?

> 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..4bc322580037
> --- /dev/null
> +++ b/crypto/asymmetric_keys/tpm2_key_rsa.c
> @@ -0,0 +1,678 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/* TPM2 asymmetric public-key crypto subtype
> + *
> + * Asymmetric TPM2 RSA key:
> + * - Decrypts RSA with TPM2_RSA_Decrypt.
> + * - Signs with PKCS#1 1.5 padding. Signing is implemented with
> + * TPM2_RSA_Decrypt operation.
> + * - Encrypts with the akcipher rsa-pcks1pad.

s/pcks1pad/pkcs1pad !

> + *
> + * 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/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 PKCS1_PAD_MIN_SIZE 11
> +
> +/* TPM2 Structures 12.2.3.5: TPMS_RSA_PARMS */
> +struct tpm2_rsa_parms {
> + __be16 symmetric;
> + __be16 scheme;
> + __be16 key_bits;
> + __be32 exponent;
> + __be16 modulus_size;
> +} __packed;
> +
> +/*
> + * 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_encode(const struct tpm2_key *key, u8 *buf)
> +{
> + const off_t o = key->priv_len + 2 + sizeof(*key->desc);
> + const struct tpm2_rsa_parms *p =
> + (const struct tpm2_rsa_parms *)&key->data[o];
> + const u16 mod_size = be16_to_cpu(p->modulus_size);
> + const void *mod = &key->data[o + sizeof(*p)];
> +
> + u8 *start = &buf[4];
> + u8 *work = &buf[4];
> + u32 seq_len;
> +
> + work[0] = 0x02; /* INTEGER */
> + work[1] = 0x82; /* u16 */
> + work[2] = mod_size >> 8;
> + work[3] = mod_size & 0xff;
> + work = &work[4];
> + memcpy(work, mod, mod_size);
> + work = &work[mod_size];
> + work[0] = 0x02; /* INTEGER */
> + work[1] = 3; /* < 128 */
> + work[2] = 1; /* 65537 */
> + work[3] = 0;
> + work[4] = 1;
> + work = &work[5];
> + seq_len = work - start;
> + buf[0] = 0x30; /* SEQUENCE */
> + buf[1] = 0x82; /* u16 */
> + buf[2] = seq_len >> 8;
> + buf[3] = seq_len & 0xff;
> +
> + /*
> + * ABI requires this according include/crypto/akcipher.h, which says

according to

> + * that there is epilogue with algorithm OID and parameters length.

is an epilogue

> + * Neither size nor semantics is documented *anywhere*, and there's no
> + * struct to hold them.
> + *
> + * So zeroing out the last eight bytes after the key blob seems like the
> + * best bet, given no better (or any) information. The size of the
> + * parameters (two u32's) was found from crypto/asymmetric/public_key.c.
> + */
> + memset(work, 0, 8);
> +
> + return seq_len + 4;
> +}
> +
> +/*
> + * 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;
> + struct akcipher_request *req;
> + struct crypto_akcipher *tfm;
> + struct crypto_wait cwait;
> + u8 *buf;
> + int ret;
> +
> + buf = kzalloc(TPM2_KEY_BYTES_MAX, GFP_KERNEL);
> + if (!buf)
> + return -ENOMEM;
> +
> + ret = tpm2_key_get_akcipher(params->encoding, params->hash_algo, cipher);
> + if (ret < 0)
> + goto err_buf;
> +
> + tfm = crypto_alloc_akcipher(cipher, 0, 0);
> + if (IS_ERR(tfm)) {
> + ret = PTR_ERR(tfm);
> + goto err_buf;
> + }
> +
> + ret = tpm2_key_rsa_encode(key, buf);
> + if (ret < 0)
> + goto err_tfm;
> +
> + ret = crypto_akcipher_set_pub_key(tfm, buf, ret);
> + if (ret < 0)
> + goto err_tfm;
> +
> + req = akcipher_request_alloc(tfm, GFP_KERNEL);
> + if (!req) {
> + ret = -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);
> +
> + ret = crypto_akcipher_encrypt(req);
> + if (ret)
> + goto err_tfm;
> +
> + ret = crypto_wait_req(ret, &cwait);
> + if (!ret)
> + ret = req->dst_len;
> +
> + akcipher_request_free(req);
> +
> +err_tfm:
> + crypto_free_akcipher(tfm);
> +
> +err_buf:
> + kfree(buf);
> + return ret;
> +}
> +
> +static int __tpm2_key_rsa_decrypt(struct tpm_chip *chip,
> + struct tpm2_key *key,
> + struct kernel_pkey_params *params,
> + const void *in, int in_len, void *out)
> +{
> + u32 key_handle = 0;
> + struct tpm_buf buf;
> + u16 decrypted_len;
> + u8 *pos;
> + int ret;
> +
> + ret = tpm_try_get_ops(chip); > + if (ret)

if (ret < 0)

> + return ret;
> +
> + ret = tpm2_start_auth_session(chip);
> + if (ret)

Uh, this one can return TPM error codes it seems from
tpm_transmit_cmd()? You probably have to do something with ret here in
case it's positive because I saw a caller of __tpm2_key_rsa_decrypt
relying on ret < 0 as error.

> + goto err_ops;
> +
> + ret = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_LOAD);
> + if (ret < 0)
> + goto err_auth;
> +
> + tpm_buf_append_name(chip, &buf, key->parent, NULL);
> + tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_CONTINUE_SESSION |
> + TPM2_SA_ENCRYPT, NULL, 0);
> + tpm_buf_append(&buf, &key->data[0], key->priv_len + key->pub_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, "TPM2_CC_LOAD");
> + 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, "TPM2_RSA_DECRYPT");
> + 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_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 *key,
> + struct kernel_pkey_params *params,
> + const void *in, void *out)
> +{
> + const u8 *ptr;
> + int out_len;
> + u8 *work;
> + int ret;
> +
> + work = kzalloc(TPM2_KEY_BYTES_MAX, 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) {

I suppose params->out_len describes the size of void *out buffer..

> + 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 *key,
> + struct kernel_pkey_params *params,
> + const void *in, void *out)
> +{
> + const off_t o = key->priv_len + 2 + sizeof(*key->desc);
> + const struct tpm2_rsa_parms *p =
> + (const struct tpm2_rsa_parms *)&key->data[o];
> + const u16 mod_size = be16_to_cpu(p->modulus_size);
> + const struct rsa_asn1_template *asn1;
> + u32 in_len = params->in_len;
> + void *asn1_wrapped = NULL;
> + 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(mod_size, GFP_KERNEL);

check NULL pointer?

> + tpm2_pad_pkcs1(in, in_len, padded, mod_size);
> + ret = __tpm2_key_rsa_decrypt(chip, key, params, padded, mod_size, 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 *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;

This seems unnecessary.

> +
> + kfree(key);
> +}
> +
> +static int tpm2_key_rsa_eds_op(struct kernel_pkey_params *params,
> + const void *in, void *out)
> +{
> + struct tpm2_key *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);

Missing verify here?

> + default:
> + return -EOPNOTSUPP;
> + }
> +}
> +
> +static int tpm2_key_rsa_verify(const struct key *key,
> + const struct public_key_signature *sig)
> +{
> + const struct tpm2_key *tpm2_key = key->payload.data[asym_crypto];
> + char alg_name[CRYPTO_MAX_ALG_NAME];
> + struct akcipher_request *req;
> + struct scatterlist src_sg[2];
> + struct crypto_akcipher *tfm;
> + struct crypto_wait cwait;
> + u8 *buf;
> + int ret;
> +
> + if (!sig->digest)
> + return -ENOPKG;
> +
> + ret = tpm2_key_get_akcipher(sig->encoding, sig->hash_algo, alg_name);
> + if (ret < 0)
> + return ret;
> +
> + buf = kzalloc(TPM2_KEY_BYTES_MAX, GFP_KERNEL);
> + if (!buf)
> + return -ENOMEM;
> +
> + tfm = crypto_alloc_akcipher(alg_name, 0, 0);
> + if (IS_ERR(tfm)) {
> + ret = PTR_ERR(tfm);
> + goto err_buf;
> + }
> +
> + ret = tpm2_key_rsa_encode(tpm2_key, buf);
> + if (ret < 0)
> + goto err_tfm;
> +
> + ret = crypto_akcipher_set_pub_key(tfm, buf, ret);
> + if (ret < 0)
> + goto err_tfm;
> +
> + ret = -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);
> + ret = crypto_wait_req(crypto_akcipher_verify(req), &cwait);
> +
> + akcipher_request_free(req);
> +
> +err_tfm:
> + crypto_free_akcipher(tfm);
> +
> +err_buf:
> + kfree(buf);
> + return ret;
> +}
> +
> +static int tpm2_key_rsa_query(const struct kernel_pkey_params *params,
> + struct kernel_pkey_query *info)
> +{
> + const struct tpm2_key *key = params->key->payload.data[asym_crypto];
> + const off_t o = key->priv_len + 2 + sizeof(*key->desc);
> + const struct tpm2_rsa_parms *p =
> + (const struct tpm2_rsa_parms *)&key->data[o];
> + const u16 mod_size = be16_to_cpu(p->modulus_size);
> + char alg_name[CRYPTO_MAX_ALG_NAME];
> + struct crypto_akcipher *tfm;
> + unsigned int len;
> + u8 *buf;
> + int ret;
> +
> + ret = tpm2_key_get_akcipher(params->encoding, params->hash_algo, alg_name);
> + if (ret < 0)
> + return ret;
> +
> + buf = kzalloc(TPM2_KEY_BYTES_MAX, GFP_KERNEL);
> + if (!buf)
> + return -ENOMEM;
> +
> + tfm = crypto_alloc_akcipher(alg_name, 0, 0);
> + if (IS_ERR(tfm)) {
> + ret = PTR_ERR(tfm);
> + goto err_buf;
> + }
> +
> + ret = tpm2_key_rsa_encode(key, buf);
> + if (ret < 0)
> + goto err_tfm;
> +
> + ret = crypto_akcipher_set_pub_key(tfm, buf, ret);
> + if (ret < 0)
> + goto err_tfm;
> +
> + len = crypto_akcipher_maxsize(tfm);
> +
> + info->key_size = mod_size * 8;
> + info->max_data_size = mod_size;
> + info->max_sig_size = len;
> + info->max_enc_size = len;
> + info->max_dec_size = mod_size;
> +
> + info->supported_ops = KEYCTL_SUPPORTS_SIGN | KEYCTL_SUPPORTS_VERIFY;
> +
> + if (!strcmp(params->encoding, "pkcs1")) {
> + pr_info("pkcs1\n");
> + info->supported_ops =
> + KEYCTL_SUPPORTS_ENCRYPT | KEYCTL_SUPPORTS_DECRYPT;
> + }
> +
> +err_tfm:
> + crypto_free_akcipher(tfm);
> + return ret;
> +
> +err_buf:
> + kfree(buf);
> + return ret;
> +}
> +
> +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);
> +
> +static int __tpm2_key_rsa_preparse(struct tpm2_key *key)
> +{
> + const off_t o = key->priv_len + 2 + sizeof(*key->desc);
> + const struct tpm2_rsa_parms *p =
> + (const struct tpm2_rsa_parms *)&key->data[o];
> +
> + if (tpm2_key_type(key) != TPM_ALG_RSA)
> + return -EBADMSG;
> +
> + if (tpm2_key_policy_size(key) != 0)
> + return -EBADMSG;
> +
> + if (be16_to_cpu(p->symmetric) != TPM_ALG_NULL)
> + return -EBADMSG;
> +
> + if (be16_to_cpu(p->scheme) != TPM_ALG_NULL)
> + return -EBADMSG;
> +
> + if (be16_to_cpu(p->key_bits) != 2048 &&
> + be16_to_cpu(p->key_bits) != 3072 &&
> + be16_to_cpu(p->key_bits) != 4096)
> + return -EBADMSG;
> +
> + if (be32_to_cpu(p->exponent) != 0x00000000 &&
> + be32_to_cpu(p->exponent) != 0x00010001)
> + return -EBADMSG;
> +
> + pr_debug("modulus_size=%u\n", be16_to_cpu(p->modulus_size));
> + return 0;
> +}
> +
> +/*
> + * Attempt to parse a data blob for a key as a TPM private key blob.
> + */
> +static int tpm2_key_rsa_preparse(struct key_preparsed_payload *prep)
> +{
> + struct tpm2_key *key;
> + int ret;
> +
> + key = tpm2_key_decode(prep->data, prep->datalen);
> + if (IS_ERR(key))
> + return ret;
> +
> + if (key->oid != OID_TPMLoadableKey) {
> + kfree(key);
> + return -EBADMSG;
> + }
> +
> + ret = __tpm2_key_rsa_preparse(key);
> + if (ret < 0) {
> + 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_rsa_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 21a67dc9efe8..d0860af7a56d 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,