From feeb7ecd2f272e1c195e51cefc0d6b0199fef1d0 Mon Sep 17 00:00:00 2001 From: Bernd Edlinger Date: Fri, 6 Sep 2019 23:38:49 +0200 Subject: [PATCH] Check the DH modulus bit length The check was missing in DH_check and DH_check_params. [extended tests] Reviewed-by: Paul Dale (Merged from https://github.com/openssl/openssl/pull/9796) --- crypto/dh/dh_check.c | 12 ++++++++++++ doc/man3/DH_generate_parameters.pod | 10 +++++++++- include/openssl/dh.h | 4 +++- test/dhtest.c | 16 +++++++++++++--- 4 files changed, 37 insertions(+), 5 deletions(-) diff --git a/crypto/dh/dh_check.c b/crypto/dh/dh_check.c index aff7e37181..373110d263 100644 --- a/crypto/dh/dh_check.c +++ b/crypto/dh/dh_check.c @@ -31,6 +31,10 @@ int DH_check_params_ex(const DH *dh) DHerr(DH_F_DH_CHECK_PARAMS_EX, DH_R_CHECK_P_NOT_PRIME); if ((errflags & DH_NOT_SUITABLE_GENERATOR) != 0) DHerr(DH_F_DH_CHECK_PARAMS_EX, DH_R_NOT_SUITABLE_GENERATOR); + if ((errflags & DH_MODULUS_TOO_SMALL) != 0) + DHerr(DH_F_DH_CHECK_PARAMS_EX, DH_R_MODULUS_TOO_SMALL); + if ((errflags & DH_MODULUS_TOO_LARGE) != 0) + DHerr(DH_F_DH_CHECK_PARAMS_EX, DH_R_MODULUS_TOO_LARGE); return errflags == 0; } @@ -58,6 +62,10 @@ int DH_check_params(const DH *dh, int *ret) goto err; if (BN_cmp(dh->g, tmp) >= 0) *ret |= DH_NOT_SUITABLE_GENERATOR; + if (BN_num_bits(dh->p) < DH_MIN_MODULUS_BITS) + *ret |= DH_MODULUS_TOO_SMALL; + if (BN_num_bits(dh->p) > OPENSSL_DH_MAX_MODULUS_BITS) + *ret |= DH_MODULUS_TOO_LARGE; ok = 1; err: @@ -91,6 +99,10 @@ int DH_check_ex(const DH *dh) DHerr(DH_F_DH_CHECK_EX, DH_R_CHECK_P_NOT_PRIME); if ((errflags & DH_CHECK_P_NOT_SAFE_PRIME) != 0) DHerr(DH_F_DH_CHECK_EX, DH_R_CHECK_P_NOT_SAFE_PRIME); + if ((errflags & DH_MODULUS_TOO_SMALL) != 0) + DHerr(DH_F_DH_CHECK_EX, DH_R_MODULUS_TOO_SMALL); + if ((errflags & DH_MODULUS_TOO_LARGE) != 0) + DHerr(DH_F_DH_CHECK_EX, DH_R_MODULUS_TOO_LARGE); return errflags == 0; } diff --git a/doc/man3/DH_generate_parameters.pod b/doc/man3/DH_generate_parameters.pod index a1541caf68..4908dcf515 100644 --- a/doc/man3/DH_generate_parameters.pod +++ b/doc/man3/DH_generate_parameters.pod @@ -73,6 +73,14 @@ The generator B is not suitable. Note that the lack of this bit doesn't guarantee that B is suitable, unless B

is known to be a strong prime. +=item DH_MODULUS_TOO_SMALL + +The modulus is too small. + +=item DH_MODULUS_TOO_LARGE + +The modulus is too large. + =back DH_check() confirms that the Diffie-Hellman parameters B are valid. The @@ -141,7 +149,7 @@ DH_generate_parameters_ex() instead. =head1 COPYRIGHT -Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved. +Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved. Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance with the License. You can obtain a copy diff --git a/include/openssl/dh.h b/include/openssl/dh.h index 7c509b4c0f..4e117a0d03 100644 --- a/include/openssl/dh.h +++ b/include/openssl/dh.h @@ -1,5 +1,5 @@ /* - * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved. + * Copyright 1995-2019 The OpenSSL Project Authors. All Rights Reserved. * * Licensed under the Apache License 2.0 (the "License"). You may not use * this file except in compliance with the License. You can obtain a copy @@ -76,6 +76,8 @@ DECLARE_ASN1_ITEM(DHparams) # define DH_CHECK_Q_NOT_PRIME 0x10 # define DH_CHECK_INVALID_Q_VALUE 0x20 # define DH_CHECK_INVALID_J_VALUE 0x40 +# define DH_MODULUS_TOO_SMALL 0x80 +# define DH_MODULUS_TOO_LARGE 0x100 /* DH_check_pub_key error codes */ # define DH_CHECK_PUBKEY_TOO_SMALL 0x01 diff --git a/test/dhtest.c b/test/dhtest.c index 662a4f32eb..e8a91f17f8 100644 --- a/test/dhtest.c +++ b/test/dhtest.c @@ -1,5 +1,5 @@ /* - * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved. + * Copyright 1995-2019 The OpenSSL Project Authors. All Rights Reserved. * * Licensed under the Apache License 2.0 (the "License"). You may not use * this file except in compliance with the License. You can obtain a copy @@ -63,14 +63,19 @@ static int dh_test(void) || !TEST_true(DH_set0_pqg(dh, p, q, g))) goto err1; + /* check fails, because p is way too small */ if (!DH_check(dh, &i)) goto err2; + i ^= DH_MODULUS_TOO_SMALL; if (!TEST_false(i & DH_CHECK_P_NOT_PRIME) || !TEST_false(i & DH_CHECK_P_NOT_SAFE_PRIME) - || !TEST_false(i & DH_CHECK_INVALID_Q_VALUE) - || !TEST_false(i & DH_CHECK_Q_NOT_PRIME) || !TEST_false(i & DH_UNABLE_TO_CHECK_GENERATOR) || !TEST_false(i & DH_NOT_SUITABLE_GENERATOR) + || !TEST_false(i & DH_CHECK_Q_NOT_PRIME) + || !TEST_false(i & DH_CHECK_INVALID_Q_VALUE) + || !TEST_false(i & DH_CHECK_INVALID_J_VALUE) + || !TEST_false(i & DH_MODULUS_TOO_SMALL) + || !TEST_false(i & DH_MODULUS_TOO_LARGE) || !TEST_false(i)) goto err2; @@ -130,6 +135,11 @@ static int dh_test(void) || !TEST_false(i & DH_CHECK_P_NOT_SAFE_PRIME) || !TEST_false(i & DH_UNABLE_TO_CHECK_GENERATOR) || !TEST_false(i & DH_NOT_SUITABLE_GENERATOR) + || !TEST_false(i & DH_CHECK_Q_NOT_PRIME) + || !TEST_false(i & DH_CHECK_INVALID_Q_VALUE) + || !TEST_false(i & DH_CHECK_INVALID_J_VALUE) + || !TEST_false(i & DH_MODULUS_TOO_SMALL) + || !TEST_false(i & DH_MODULUS_TOO_LARGE) || !TEST_false(i)) goto err3; -- 2.25.1