diff options
| author | Mahmoud Adam <mngyadam@amazon.com> | 2023-06-13 16:17:31 +0000 |
|---|---|---|
| committer | Herbert Xu <herbert@gondor.apana.org.au> | 2023-06-23 16:15:36 +0800 |
| commit | 6637e11e4ad22ff03183da0dbd36d65c98b81cf7 (patch) | |
| tree | 90bdebeb49e1658dfdacc3069fdc36c7fc99d931 /crypto/rsa.c | |
| parent | ba51738fa78972fb446b49b6b9ddda4058a272e0 (diff) | |
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>
Diffstat (limited to 'crypto/rsa.c')
| -rw-r--r-- | crypto/rsa.c | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/crypto/rsa.c b/crypto/rsa.c index c50f2d2a4d06..c79613cdce6e 100644 --- a/crypto/rsa.c +++ b/crypto/rsa.c @@ -205,6 +205,32 @@ static int rsa_check_key_length(unsigned int len) 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) { @@ -232,6 +258,11 @@ static int rsa_set_pub_key(struct crypto_akcipher *tfm, const void *key, return -EINVAL; } + if (fips_enabled && rsa_check_exponent_fips(mpi_key->e)) { + rsa_free_mpi_key(mpi_key); + return -EINVAL; + } + return 0; err: @@ -290,6 +321,11 @@ static int rsa_set_priv_key(struct crypto_akcipher *tfm, const void *key, return -EINVAL; } + if (fips_enabled && rsa_check_exponent_fips(mpi_key->e)) { + rsa_free_mpi_key(mpi_key); + return -EINVAL; + } + return 0; err: |