// 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");