From: Vitaly Chikunov vt@altlinux.org
[ Upstream commit 2eb4942b6609d35a4e835644a33203b0aef7443d ]
Currently used scalar multiplication algorithm (Matthieu Rivain, 2011) have invalid values for scalar == 1, n-1, and for regularized version n-2, which was previously not checked. Verify that they are not used as private keys.
Signed-off-by: Vitaly Chikunov vt@altlinux.org Signed-off-by: Herbert Xu herbert@gondor.apana.org.au Signed-off-by: Sasha Levin sashal@kernel.org --- crypto/ecc.c | 42 ++++++++++++++++++++++++++---------------- 1 file changed, 26 insertions(+), 16 deletions(-)
diff --git a/crypto/ecc.c b/crypto/ecc.c index 18f32f2a5e1c9..3b422e24e647e 100644 --- a/crypto/ecc.c +++ b/crypto/ecc.c @@ -904,30 +904,43 @@ static inline void ecc_swap_digits(const u64 *in, u64 *out, out[i] = __swab64(in[ndigits - 1 - i]); }
-int ecc_is_key_valid(unsigned int curve_id, unsigned int ndigits, - const u64 *private_key, unsigned int private_key_len) +static int __ecc_is_key_valid(const struct ecc_curve *curve, + const u64 *private_key, unsigned int ndigits) { - int nbytes; - const struct ecc_curve *curve = ecc_get_curve(curve_id); + u64 one[ECC_MAX_DIGITS] = { 1, }; + u64 res[ECC_MAX_DIGITS];
if (!private_key) return -EINVAL;
- nbytes = ndigits << ECC_DIGITS_TO_BYTES_SHIFT; - - if (private_key_len != nbytes) + if (curve->g.ndigits != ndigits) return -EINVAL;
- if (vli_is_zero(private_key, ndigits)) + /* Make sure the private key is in the range [2, n-3]. */ + if (vli_cmp(one, private_key, ndigits) != -1) return -EINVAL; - - /* Make sure the private key is in the range [1, n-1]. */ - if (vli_cmp(curve->n, private_key, ndigits) != 1) + vli_sub(res, curve->n, one, ndigits); + vli_sub(res, res, one, ndigits); + if (vli_cmp(res, private_key, ndigits) != 1) return -EINVAL;
return 0; }
+int ecc_is_key_valid(unsigned int curve_id, unsigned int ndigits, + const u64 *private_key, unsigned int private_key_len) +{ + int nbytes; + const struct ecc_curve *curve = ecc_get_curve(curve_id); + + nbytes = ndigits << ECC_DIGITS_TO_BYTES_SHIFT; + + if (private_key_len != nbytes) + return -EINVAL; + + return __ecc_is_key_valid(curve, private_key, ndigits); +} + /* * ECC private keys are generated using the method of extra random bits, * equivalent to that described in FIPS 186-4, Appendix B.4.1. @@ -971,11 +984,8 @@ int ecc_gen_privkey(unsigned int curve_id, unsigned int ndigits, u64 *privkey) if (err) return err;
- if (vli_is_zero(priv, ndigits)) - return -EINVAL; - - /* Make sure the private key is in the range [1, n-1]. */ - if (vli_cmp(curve->n, priv, ndigits) != 1) + /* Make sure the private key is in the valid range. */ + if (__ecc_is_key_valid(curve, priv, ndigits)) return -EINVAL;
ecc_swap_digits(priv, privkey, ndigits);