diff options
Diffstat (limited to 'crypto/rsa.c')
| -rw-r--r-- | crypto/rsa.c | 285 |
1 files changed, 285 insertions, 0 deletions
diff --git a/crypto/rsa.c b/crypto/rsa.c new file mode 100644 index 000000000..4cdbec95d --- /dev/null +++ b/crypto/rsa.c @@ -0,0 +1,285 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* RSA asymmetric public-key algorithm [RFC3447] + * + * Copyright (c) 2015, Intel Corporation + * Authors: Tadeusz Struk <tadeusz.struk@intel.com> + */ + +#include <linux/module.h> +#include <linux/mpi.h> +#include <crypto/internal/rsa.h> +#include <crypto/internal/akcipher.h> +#include <crypto/akcipher.h> +#include <crypto/algapi.h> + +struct rsa_mpi_key { + MPI n; + MPI e; + MPI d; +}; + +/* + * RSAEP function [RFC3447 sec 5.1.1] + * c = m^e mod n; + */ +static int _rsa_enc(const struct rsa_mpi_key *key, MPI c, MPI m) +{ + /* (1) Validate 0 <= m < n */ + if (mpi_cmp_ui(m, 0) < 0 || mpi_cmp(m, key->n) >= 0) + return -EINVAL; + + /* (2) c = m^e mod n */ + return mpi_powm(c, m, key->e, key->n); +} + +/* + * RSADP function [RFC3447 sec 5.1.2] + * m = c^d mod n; + */ +static int _rsa_dec(const struct rsa_mpi_key *key, MPI m, MPI c) +{ + /* (1) Validate 0 <= c < n */ + if (mpi_cmp_ui(c, 0) < 0 || mpi_cmp(c, key->n) >= 0) + return -EINVAL; + + /* (2) m = c^d mod n */ + return mpi_powm(m, c, key->d, key->n); +} + +static inline struct rsa_mpi_key *rsa_get_key(struct crypto_akcipher *tfm) +{ + return akcipher_tfm_ctx(tfm); +} + +static int rsa_enc(struct akcipher_request *req) +{ + struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req); + const struct rsa_mpi_key *pkey = rsa_get_key(tfm); + MPI m, c = mpi_alloc(0); + int ret = 0; + int sign; + + if (!c) + return -ENOMEM; + + if (unlikely(!pkey->n || !pkey->e)) { + ret = -EINVAL; + goto err_free_c; + } + + ret = -ENOMEM; + m = mpi_read_raw_from_sgl(req->src, req->src_len); + if (!m) + goto err_free_c; + + ret = _rsa_enc(pkey, c, m); + if (ret) + goto err_free_m; + + ret = mpi_write_to_sgl(c, req->dst, req->dst_len, &sign); + if (ret) + goto err_free_m; + + if (sign < 0) + ret = -EBADMSG; + +err_free_m: + mpi_free(m); +err_free_c: + mpi_free(c); + return ret; +} + +static int rsa_dec(struct akcipher_request *req) +{ + struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req); + const struct rsa_mpi_key *pkey = rsa_get_key(tfm); + MPI c, m = mpi_alloc(0); + int ret = 0; + int sign; + + if (!m) + return -ENOMEM; + + if (unlikely(!pkey->n || !pkey->d)) { + ret = -EINVAL; + goto err_free_m; + } + + ret = -ENOMEM; + c = mpi_read_raw_from_sgl(req->src, req->src_len); + if (!c) + goto err_free_m; + + ret = _rsa_dec(pkey, m, c); + if (ret) + goto err_free_c; + + ret = mpi_write_to_sgl(m, req->dst, req->dst_len, &sign); + if (ret) + goto err_free_c; + + if (sign < 0) + ret = -EBADMSG; +err_free_c: + mpi_free(c); +err_free_m: + mpi_free(m); + return ret; +} + +static void rsa_free_mpi_key(struct rsa_mpi_key *key) +{ + mpi_free(key->d); + mpi_free(key->e); + mpi_free(key->n); + key->d = NULL; + key->e = NULL; + key->n = NULL; +} + +static int rsa_check_key_length(unsigned int len) +{ + switch (len) { + case 512: + case 1024: + case 1536: + case 2048: + case 3072: + case 4096: + return 0; + } + + return -EINVAL; +} + +static int rsa_set_pub_key(struct crypto_akcipher *tfm, const void *key, + unsigned int keylen) +{ + struct rsa_mpi_key *mpi_key = akcipher_tfm_ctx(tfm); + struct rsa_key raw_key = {0}; + int ret; + + /* Free the old MPI key if any */ + rsa_free_mpi_key(mpi_key); + + ret = rsa_parse_pub_key(&raw_key, key, keylen); + if (ret) + return ret; + + mpi_key->e = mpi_read_raw_data(raw_key.e, raw_key.e_sz); + if (!mpi_key->e) + goto err; + + mpi_key->n = mpi_read_raw_data(raw_key.n, raw_key.n_sz); + if (!mpi_key->n) + goto err; + + if (rsa_check_key_length(mpi_get_size(mpi_key->n) << 3)) { + rsa_free_mpi_key(mpi_key); + return -EINVAL; + } + + return 0; + +err: + rsa_free_mpi_key(mpi_key); + return -ENOMEM; +} + +static int rsa_set_priv_key(struct crypto_akcipher *tfm, const void *key, + unsigned int keylen) +{ + struct rsa_mpi_key *mpi_key = akcipher_tfm_ctx(tfm); + struct rsa_key raw_key = {0}; + int ret; + + /* Free the old MPI key if any */ + rsa_free_mpi_key(mpi_key); + + ret = rsa_parse_priv_key(&raw_key, key, keylen); + if (ret) + return ret; + + mpi_key->d = mpi_read_raw_data(raw_key.d, raw_key.d_sz); + if (!mpi_key->d) + goto err; + + mpi_key->e = mpi_read_raw_data(raw_key.e, raw_key.e_sz); + if (!mpi_key->e) + goto err; + + mpi_key->n = mpi_read_raw_data(raw_key.n, raw_key.n_sz); + if (!mpi_key->n) + goto err; + + if (rsa_check_key_length(mpi_get_size(mpi_key->n) << 3)) { + rsa_free_mpi_key(mpi_key); + return -EINVAL; + } + + return 0; + +err: + rsa_free_mpi_key(mpi_key); + return -ENOMEM; +} + +static unsigned int rsa_max_size(struct crypto_akcipher *tfm) +{ + struct rsa_mpi_key *pkey = akcipher_tfm_ctx(tfm); + + return mpi_get_size(pkey->n); +} + +static void rsa_exit_tfm(struct crypto_akcipher *tfm) +{ + struct rsa_mpi_key *pkey = akcipher_tfm_ctx(tfm); + + rsa_free_mpi_key(pkey); +} + +static struct akcipher_alg rsa = { + .encrypt = rsa_enc, + .decrypt = rsa_dec, + .set_priv_key = rsa_set_priv_key, + .set_pub_key = rsa_set_pub_key, + .max_size = rsa_max_size, + .exit = rsa_exit_tfm, + .base = { + .cra_name = "rsa", + .cra_driver_name = "rsa-generic", + .cra_priority = 100, + .cra_module = THIS_MODULE, + .cra_ctxsize = sizeof(struct rsa_mpi_key), + }, +}; + +static int rsa_init(void) +{ + int err; + + err = crypto_register_akcipher(&rsa); + if (err) + return err; + + err = crypto_register_template(&rsa_pkcs1pad_tmpl); + if (err) { + crypto_unregister_akcipher(&rsa); + return err; + } + + return 0; +} + +static void rsa_exit(void) +{ + crypto_unregister_template(&rsa_pkcs1pad_tmpl); + crypto_unregister_akcipher(&rsa); +} + +subsys_initcall(rsa_init); +module_exit(rsa_exit); +MODULE_ALIAS_CRYPTO("rsa"); +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("RSA generic algorithm"); |