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kernel/crypto/rsa.c
Mahmoud Adam 6637e11e4a crypto: rsa - allow only odd e and restrict value in FIPS mode 
check if rsa public exponent is odd and check its value is between
2^16 < e < 2^256.

FIPS 186-5 DSS (page 35)[1] specify that:
1. The public exponent e shall be selected with the following constraints:
  (a) The public verification exponent e shall be selected prior to
  generating the primes, p and q, and the private signature exponent
  d.
  (b) The exponent e shall be an odd positive integer such that:
   2^16 < e < 2^256.

[1] https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.186-5.pdf

Signed-off-by: Mahmoud Adam <mngyadam@amazon.com>
Reviewed-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2023-06-23 16:15:36 +08:00

393 lines
7.4 KiB
C
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// 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/fips.h>
#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;
MPI p;
MPI q;
MPI dp;
MPI dq;
MPI qinv;
};
/*
* 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_1 = c^dP mod p;
* m_2 = c^dQ mod q;
* h = (m_1 - m_2) * qInv mod p;
* m = m_2 + q * h;
*/
static int _rsa_dec_crt(const struct rsa_mpi_key *key, MPI m_or_m1_or_h, MPI c)
{
MPI m2, m12_or_qh;
int ret = -ENOMEM;
/* (1) Validate 0 <= c < n */
if (mpi_cmp_ui(c, 0) < 0 || mpi_cmp(c, key->n) >= 0)
return -EINVAL;
m2 = mpi_alloc(0);
m12_or_qh = mpi_alloc(0);
if (!m2 || !m12_or_qh)
goto err_free_mpi;
/* (2i) m_1 = c^dP mod p */
ret = mpi_powm(m_or_m1_or_h, c, key->dp, key->p);
if (ret)
goto err_free_mpi;
/* (2i) m_2 = c^dQ mod q */
ret = mpi_powm(m2, c, key->dq, key->q);
if (ret)
goto err_free_mpi;
/* (2iii) h = (m_1 - m_2) * qInv mod p */
mpi_sub(m12_or_qh, m_or_m1_or_h, m2);
mpi_mulm(m_or_m1_or_h, m12_or_qh, key->qinv, key->p);
/* (2iv) m = m_2 + q * h */
mpi_mul(m12_or_qh, key->q, m_or_m1_or_h);
mpi_addm(m_or_m1_or_h, m2, m12_or_qh, key->n);
ret = 0;
err_free_mpi:
mpi_free(m12_or_qh);
mpi_free(m2);
return ret;
}
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_crt(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);
mpi_free(key->p);
mpi_free(key->q);
mpi_free(key->dp);
mpi_free(key->dq);
mpi_free(key->qinv);
key->d = NULL;
key->e = NULL;
key->n = NULL;
key->p = NULL;
key->q = NULL;
key->dp = NULL;
key->dq = NULL;
key->qinv = NULL;
}
static int rsa_check_key_length(unsigned int len)
{
switch (len) {
case 512:
case 1024:
case 1536:
if (fips_enabled)
return -EINVAL;
fallthrough;
case 2048:
case 3072:
case 4096:
return 0;
}
return -EINVAL;
}
static int rsa_check_exponent_fips(MPI e)
{
MPI e_max = NULL;
/* check if odd */
if (!mpi_test_bit(e, 0)) {
return -EINVAL;
}
/* check if 2^16 < e < 2^256. */
if (mpi_cmp_ui(e, 65536) <= 0) {
return -EINVAL;
}
e_max = mpi_alloc(0);
mpi_set_bit(e_max, 256);
if (mpi_cmp(e, e_max) >= 0) {
mpi_free(e_max);
return -EINVAL;
}
mpi_free(e_max);
return 0;
}
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;
}
if (fips_enabled && rsa_check_exponent_fips(mpi_key->e)) {
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;
mpi_key->p = mpi_read_raw_data(raw_key.p, raw_key.p_sz);
if (!mpi_key->p)
goto err;
mpi_key->q = mpi_read_raw_data(raw_key.q, raw_key.q_sz);
if (!mpi_key->q)
goto err;
mpi_key->dp = mpi_read_raw_data(raw_key.dp, raw_key.dp_sz);
if (!mpi_key->dp)
goto err;
mpi_key->dq = mpi_read_raw_data(raw_key.dq, raw_key.dq_sz);
if (!mpi_key->dq)
goto err;
mpi_key->qinv = mpi_read_raw_data(raw_key.qinv, raw_key.qinv_sz);
if (!mpi_key->qinv)
goto err;
if (rsa_check_key_length(mpi_get_size(mpi_key->n) << 3)) {
rsa_free_mpi_key(mpi_key);
return -EINVAL;
}
if (fips_enabled && rsa_check_exponent_fips(mpi_key->e)) {
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 __init 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 __exit 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");
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