394 lines
7.4 KiB
C
394 lines
7.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* RSA asymmetric public-key algorithm [RFC3447]
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*
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* Copyright (c) 2015, Intel Corporation
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* Authors: Tadeusz Struk <tadeusz.struk@intel.com>
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*/
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#include <linux/fips.h>
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#include <linux/module.h>
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#include <linux/mpi.h>
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#include <crypto/internal/rsa.h>
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#include <crypto/internal/akcipher.h>
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#include <crypto/akcipher.h>
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#include <crypto/algapi.h>
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struct rsa_mpi_key {
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MPI n;
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MPI e;
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MPI d;
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MPI p;
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MPI q;
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MPI dp;
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MPI dq;
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MPI qinv;
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};
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/*
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* RSAEP function [RFC3447 sec 5.1.1]
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* c = m^e mod n;
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*/
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static int _rsa_enc(const struct rsa_mpi_key *key, MPI c, MPI m)
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{
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/* (1) Validate 0 <= m < n */
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if (mpi_cmp_ui(m, 0) < 0 || mpi_cmp(m, key->n) >= 0)
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return -EINVAL;
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/* (2) c = m^e mod n */
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return mpi_powm(c, m, key->e, key->n);
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}
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/*
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* RSADP function [RFC3447 sec 5.1.2]
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* m_1 = c^dP mod p;
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* m_2 = c^dQ mod q;
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* h = (m_1 - m_2) * qInv mod p;
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* m = m_2 + q * h;
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*/
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static int _rsa_dec_crt(const struct rsa_mpi_key *key, MPI m_or_m1_or_h, MPI c)
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{
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MPI m2, m12_or_qh;
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int ret = -ENOMEM;
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/* (1) Validate 0 <= c < n */
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if (mpi_cmp_ui(c, 0) < 0 || mpi_cmp(c, key->n) >= 0)
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return -EINVAL;
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m2 = mpi_alloc(0);
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m12_or_qh = mpi_alloc(0);
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if (!m2 || !m12_or_qh)
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goto err_free_mpi;
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/* (2i) m_1 = c^dP mod p */
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ret = mpi_powm(m_or_m1_or_h, c, key->dp, key->p);
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if (ret)
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goto err_free_mpi;
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/* (2i) m_2 = c^dQ mod q */
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ret = mpi_powm(m2, c, key->dq, key->q);
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if (ret)
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goto err_free_mpi;
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/* (2iii) h = (m_1 - m_2) * qInv mod p */
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mpi_sub(m12_or_qh, m_or_m1_or_h, m2);
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mpi_mulm(m_or_m1_or_h, m12_or_qh, key->qinv, key->p);
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/* (2iv) m = m_2 + q * h */
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mpi_mul(m12_or_qh, key->q, m_or_m1_or_h);
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mpi_addm(m_or_m1_or_h, m2, m12_or_qh, key->n);
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ret = 0;
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err_free_mpi:
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mpi_free(m12_or_qh);
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mpi_free(m2);
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return ret;
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}
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static inline struct rsa_mpi_key *rsa_get_key(struct crypto_akcipher *tfm)
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{
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return akcipher_tfm_ctx(tfm);
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}
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static int rsa_enc(struct akcipher_request *req)
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{
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struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
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const struct rsa_mpi_key *pkey = rsa_get_key(tfm);
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MPI m, c = mpi_alloc(0);
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int ret = 0;
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int sign;
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if (!c)
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return -ENOMEM;
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if (unlikely(!pkey->n || !pkey->e)) {
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ret = -EINVAL;
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goto err_free_c;
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}
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ret = -ENOMEM;
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m = mpi_read_raw_from_sgl(req->src, req->src_len);
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if (!m)
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goto err_free_c;
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ret = _rsa_enc(pkey, c, m);
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if (ret)
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goto err_free_m;
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ret = mpi_write_to_sgl(c, req->dst, req->dst_len, &sign);
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if (ret)
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goto err_free_m;
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if (sign < 0)
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ret = -EBADMSG;
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err_free_m:
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mpi_free(m);
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err_free_c:
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mpi_free(c);
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return ret;
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}
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static int rsa_dec(struct akcipher_request *req)
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{
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struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
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const struct rsa_mpi_key *pkey = rsa_get_key(tfm);
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MPI c, m = mpi_alloc(0);
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int ret = 0;
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int sign;
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if (!m)
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return -ENOMEM;
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if (unlikely(!pkey->n || !pkey->d)) {
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ret = -EINVAL;
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goto err_free_m;
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}
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ret = -ENOMEM;
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c = mpi_read_raw_from_sgl(req->src, req->src_len);
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if (!c)
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goto err_free_m;
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ret = _rsa_dec_crt(pkey, m, c);
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if (ret)
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goto err_free_c;
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ret = mpi_write_to_sgl(m, req->dst, req->dst_len, &sign);
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if (ret)
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goto err_free_c;
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if (sign < 0)
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ret = -EBADMSG;
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err_free_c:
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mpi_free(c);
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err_free_m:
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mpi_free(m);
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return ret;
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}
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static void rsa_free_mpi_key(struct rsa_mpi_key *key)
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{
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mpi_free(key->d);
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mpi_free(key->e);
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mpi_free(key->n);
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mpi_free(key->p);
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mpi_free(key->q);
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mpi_free(key->dp);
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mpi_free(key->dq);
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mpi_free(key->qinv);
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key->d = NULL;
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key->e = NULL;
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key->n = NULL;
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key->p = NULL;
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key->q = NULL;
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key->dp = NULL;
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key->dq = NULL;
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key->qinv = NULL;
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}
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static int rsa_check_key_length(unsigned int len)
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{
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switch (len) {
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case 512:
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case 1024:
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case 1536:
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if (fips_enabled)
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return -EINVAL;
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fallthrough;
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case 2048:
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case 3072:
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case 4096:
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return 0;
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}
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return -EINVAL;
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}
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static int rsa_check_exponent_fips(MPI e)
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{
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MPI e_max = NULL;
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/* check if odd */
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if (!mpi_test_bit(e, 0)) {
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return -EINVAL;
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}
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/* check if 2^16 < e < 2^256. */
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if (mpi_cmp_ui(e, 65536) <= 0) {
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return -EINVAL;
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}
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e_max = mpi_alloc(0);
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mpi_set_bit(e_max, 256);
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if (mpi_cmp(e, e_max) >= 0) {
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mpi_free(e_max);
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return -EINVAL;
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}
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mpi_free(e_max);
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return 0;
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}
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static int rsa_set_pub_key(struct crypto_akcipher *tfm, const void *key,
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unsigned int keylen)
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{
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struct rsa_mpi_key *mpi_key = akcipher_tfm_ctx(tfm);
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struct rsa_key raw_key = {0};
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int ret;
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/* Free the old MPI key if any */
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rsa_free_mpi_key(mpi_key);
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ret = rsa_parse_pub_key(&raw_key, key, keylen);
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if (ret)
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return ret;
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mpi_key->e = mpi_read_raw_data(raw_key.e, raw_key.e_sz);
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if (!mpi_key->e)
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goto err;
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mpi_key->n = mpi_read_raw_data(raw_key.n, raw_key.n_sz);
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if (!mpi_key->n)
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goto err;
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if (rsa_check_key_length(mpi_get_size(mpi_key->n) << 3)) {
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rsa_free_mpi_key(mpi_key);
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return -EINVAL;
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}
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if (fips_enabled && rsa_check_exponent_fips(mpi_key->e)) {
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rsa_free_mpi_key(mpi_key);
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return -EINVAL;
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}
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return 0;
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err:
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rsa_free_mpi_key(mpi_key);
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return -ENOMEM;
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}
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static int rsa_set_priv_key(struct crypto_akcipher *tfm, const void *key,
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unsigned int keylen)
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{
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struct rsa_mpi_key *mpi_key = akcipher_tfm_ctx(tfm);
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struct rsa_key raw_key = {0};
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int ret;
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/* Free the old MPI key if any */
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rsa_free_mpi_key(mpi_key);
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ret = rsa_parse_priv_key(&raw_key, key, keylen);
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if (ret)
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return ret;
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mpi_key->d = mpi_read_raw_data(raw_key.d, raw_key.d_sz);
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if (!mpi_key->d)
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goto err;
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mpi_key->e = mpi_read_raw_data(raw_key.e, raw_key.e_sz);
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if (!mpi_key->e)
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goto err;
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mpi_key->n = mpi_read_raw_data(raw_key.n, raw_key.n_sz);
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if (!mpi_key->n)
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goto err;
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mpi_key->p = mpi_read_raw_data(raw_key.p, raw_key.p_sz);
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if (!mpi_key->p)
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goto err;
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mpi_key->q = mpi_read_raw_data(raw_key.q, raw_key.q_sz);
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if (!mpi_key->q)
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goto err;
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mpi_key->dp = mpi_read_raw_data(raw_key.dp, raw_key.dp_sz);
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if (!mpi_key->dp)
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goto err;
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mpi_key->dq = mpi_read_raw_data(raw_key.dq, raw_key.dq_sz);
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if (!mpi_key->dq)
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goto err;
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mpi_key->qinv = mpi_read_raw_data(raw_key.qinv, raw_key.qinv_sz);
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if (!mpi_key->qinv)
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goto err;
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if (rsa_check_key_length(mpi_get_size(mpi_key->n) << 3)) {
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rsa_free_mpi_key(mpi_key);
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return -EINVAL;
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}
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if (fips_enabled && rsa_check_exponent_fips(mpi_key->e)) {
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rsa_free_mpi_key(mpi_key);
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return -EINVAL;
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}
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return 0;
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err:
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rsa_free_mpi_key(mpi_key);
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return -ENOMEM;
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}
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static unsigned int rsa_max_size(struct crypto_akcipher *tfm)
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{
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struct rsa_mpi_key *pkey = akcipher_tfm_ctx(tfm);
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return mpi_get_size(pkey->n);
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}
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static void rsa_exit_tfm(struct crypto_akcipher *tfm)
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{
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struct rsa_mpi_key *pkey = akcipher_tfm_ctx(tfm);
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rsa_free_mpi_key(pkey);
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}
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static struct akcipher_alg rsa = {
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.encrypt = rsa_enc,
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.decrypt = rsa_dec,
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.set_priv_key = rsa_set_priv_key,
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.set_pub_key = rsa_set_pub_key,
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.max_size = rsa_max_size,
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.exit = rsa_exit_tfm,
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.base = {
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.cra_name = "rsa",
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.cra_driver_name = "rsa-generic",
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.cra_priority = 100,
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.cra_module = THIS_MODULE,
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.cra_ctxsize = sizeof(struct rsa_mpi_key),
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},
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};
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static int __init rsa_init(void)
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{
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int err;
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err = crypto_register_akcipher(&rsa);
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if (err)
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return err;
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err = crypto_register_template(&rsa_pkcs1pad_tmpl);
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if (err) {
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crypto_unregister_akcipher(&rsa);
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return err;
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}
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return 0;
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}
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static void __exit rsa_exit(void)
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{
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crypto_unregister_template(&rsa_pkcs1pad_tmpl);
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crypto_unregister_akcipher(&rsa);
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}
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subsys_initcall(rsa_init);
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module_exit(rsa_exit);
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MODULE_ALIAS_CRYPTO("rsa");
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("RSA generic algorithm");
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