/* RSA asymmetric public-key algorithm [RFC3447] * * Copyright (c) 2015, Intel Corporation * Authors: Tadeusz Struk <tadeusz.struk@intel.com> * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public Licence * as published by the Free Software Foundation; either version * 2 of the Licence, or (at your option) any later version. */ #include <linux/module.h> #include <crypto/internal/rsa.h> #include <crypto/internal/akcipher.h> #include <crypto/akcipher.h> /* * RSAEP function [RFC3447 sec 5.1.1] * c = m^e mod n; */ static int _rsa_enc(const struct rsa_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_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); } /* * RSASP1 function [RFC3447 sec 5.2.1] * s = m^d mod n */ static int _rsa_sign(const struct rsa_key *key, MPI s, MPI m) { /* (1) Validate 0 <= m < n */ if (mpi_cmp_ui(m, 0) < 0 || mpi_cmp(m, key->n) >= 0) return -EINVAL; /* (2) s = m^d mod n */ return mpi_powm(s, m, key->d, key->n); } /* * RSAVP1 function [RFC3447 sec 5.2.2] * m = s^e mod n; */ static int _rsa_verify(const struct rsa_key *key, MPI m, MPI s) { /* (1) Validate 0 <= s < n */ if (mpi_cmp_ui(s, 0) < 0 || mpi_cmp(s, key->n) >= 0) return -EINVAL; /* (2) m = s^e mod n */ return mpi_powm(m, s, key->e, key->n); } static inline struct rsa_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_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; } if (req->dst_len < mpi_get_size(pkey->n)) { req->dst_len = mpi_get_size(pkey->n); ret = -EOVERFLOW; goto err_free_c; } m = mpi_read_raw_data(req->src, req->src_len); if (!m) { ret = -ENOMEM; goto err_free_c; } ret = _rsa_enc(pkey, c, m); if (ret) goto err_free_m; ret = mpi_read_buffer(c, req->dst, req->dst_len, &req->dst_len, &sign); if (ret) goto err_free_m; if (sign < 0) { ret = -EBADMSG; goto err_free_m; } 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_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; } if (req->dst_len < mpi_get_size(pkey->n)) { req->dst_len = mpi_get_size(pkey->n); ret = -EOVERFLOW; goto err_free_m; } c = mpi_read_raw_data(req->src, req->src_len); if (!c) { ret = -ENOMEM; goto err_free_m; } ret = _rsa_dec(pkey, m, c); if (ret) goto err_free_c; ret = mpi_read_buffer(m, req->dst, req->dst_len, &req->dst_len, &sign); if (ret) goto err_free_c; if (sign < 0) { ret = -EBADMSG; goto err_free_c; } err_free_c: mpi_free(c); err_free_m: mpi_free(m); return ret; } static int rsa_sign(struct akcipher_request *req) { struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req); const struct rsa_key *pkey = rsa_get_key(tfm); MPI m, s = mpi_alloc(0); int ret = 0; int sign; if (!s) return -ENOMEM; if (unlikely(!pkey->n || !pkey->d)) { ret = -EINVAL; goto err_free_s; } if (req->dst_len < mpi_get_size(pkey->n)) { req->dst_len = mpi_get_size(pkey->n); ret = -EOVERFLOW; goto err_free_s; } m = mpi_read_raw_data(req->src, req->src_len); if (!m) { ret = -ENOMEM; goto err_free_s; } ret = _rsa_sign(pkey, s, m); if (ret) goto err_free_m; ret = mpi_read_buffer(s, req->dst, req->dst_len, &req->dst_len, &sign); if (ret) goto err_free_m; if (sign < 0) { ret = -EBADMSG; goto err_free_m; } err_free_m: mpi_free(m); err_free_s: mpi_free(s); return ret; } static int rsa_verify(struct akcipher_request *req) { struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req); const struct rsa_key *pkey = rsa_get_key(tfm); MPI s, m = mpi_alloc(0); int ret = 0; int sign; if (!m) return -ENOMEM; if (unlikely(!pkey->n || !pkey->e)) { ret = -EINVAL; goto err_free_m; } if (req->dst_len < mpi_get_size(pkey->n)) { req->dst_len = mpi_get_size(pkey->n); ret = -EOVERFLOW; goto err_free_m; } s = mpi_read_raw_data(req->src, req->src_len); if (!s) { ret = -ENOMEM; goto err_free_m; } ret = _rsa_verify(pkey, m, s); if (ret) goto err_free_s; ret = mpi_read_buffer(m, req->dst, req->dst_len, &req->dst_len, &sign); if (ret) goto err_free_s; if (sign < 0) { ret = -EBADMSG; goto err_free_s; } err_free_s: mpi_free(s); err_free_m: mpi_free(m); return ret; } 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_setkey(struct crypto_akcipher *tfm, const void *key, unsigned int keylen) { struct rsa_key *pkey = akcipher_tfm_ctx(tfm); int ret; ret = rsa_parse_key(pkey, key, keylen); if (ret) return ret; if (rsa_check_key_length(mpi_get_size(pkey->n) << 3)) { rsa_free_key(pkey); ret = -EINVAL; } return ret; } static void rsa_exit_tfm(struct crypto_akcipher *tfm) { struct rsa_key *pkey = akcipher_tfm_ctx(tfm); rsa_free_key(pkey); } static struct akcipher_alg rsa = { .encrypt = rsa_enc, .decrypt = rsa_dec, .sign = rsa_sign, .verify = rsa_verify, .setkey = rsa_setkey, .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_key), }, }; static int rsa_init(void) { return crypto_register_akcipher(&rsa); } static void rsa_exit(void) { crypto_unregister_akcipher(&rsa); } module_init(rsa_init); module_exit(rsa_exit); MODULE_ALIAS_CRYPTO("rsa"); MODULE_LICENSE("GPL"); MODULE_DESCRIPTION("RSA generic algorithm");