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

Bharat Bhushan
2024-05-21T07:26:01Z

> -----Original Message-----
> From: Jarkko Sakkinen <jarkko@kernel.org>
> Sent: Tuesday, May 21, 2024 8:47 AM
> To: Herbert Xu <herbert@gondor.apana.org.au>
> Cc: linux-integrity@vger.kernel.org; keyrings@vger.kernel.org;
> Andreas.Fuchs@infineon.com; James Prestwood <prestwoj@gmail.com>;
> David Woodhouse <dwmw2@infradead.org>; Eric Biggers
> <ebiggers@kernel.org>; James Bottomley
> <James.Bottomley@hansenpartnership.com>; Jarkko Sakkinen
> <jarkko@kernel.org>; David S. Miller <davem@davemloft.net>; open
> list:CRYPTO API <linux-crypto@vger.kernel.org>; open list <linux-
> kernel@vger.kernel.org>; David Howells <dhowells@redhat.com>; James
> Bottomley <James.Bottomley@HansenPartnership.com>; Stefan Berger
> <stefanb@linux.ibm.com>; Ard Biesheuvel <ardb@kernel.org>; Mario
> Limonciello <mario.limonciello@amd.com>
> Subject: [EXTERNAL] [PATCH v2 6/6] keys: asymmetric:
> ASYMMETRIC_TPM2_KEY_RSA_SUBTYPE
>
> ----------------------------------------------------------------------
> 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://urldefense.proofpoint.com/v2/url?u=https-
> 3A__lore.kernel.org_all_20200518172704.29608-2D1-2Dprestwoj-
> 40gmail.com_&d=DwIDAg&c=nKjWec2b6R0mOyPaz7xtfQ&r=PAAlWswPe7d8
> gHlGbCLmy2YezyK7O3Hv_t2heGnouBw&m=OMixrhGWcekpXpja15IeSeghOU
> 4mBNCZOSB2Vgtzbn7xcodoWU_Hnnpzp_eZh-
> XR&s=pKVMCPyvi19wJur3Bzq2xo3MtPHsEicDLBGr--NWRjs&e=
> 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);
> +

Few Minor comments,
Extra line here

> + 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;
> + }

Do we need braces here?

> +
> + 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;

Maybe use ERR_PTR() here and couple of more places

> +
> + 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
>