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Make DH_check_pub_key() and DH_generate_key() safer yet 

We already check for an excessively large P in DH_generate_key(), but not in
DH_check_pub_key(), and none of them check for an excessively large Q.

This change adds all the missing excessive size checks of P and Q.

It's to be noted that behaviours surrounding excessively sized P and Q
differ.  DH_check() raises an error on the excessively sized P, but only
sets a flag for the excessively sized Q.  This behaviour is mimicked in
DH_check_pub_key().

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Hugo Landau <hlandau@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/22518)

(cherry picked from commit ddeb4b6c6d)
This commit is contained in:
Richard Levitte 2023-10-20 09:18:19 +02:00 committed by Hugo Landau
parent b37871cd0a
commit db925ae2e6
No known key found for this signature in database
GPG Key ID: 3D30A3A9FF1360DC
7 changed files with 33 additions and 6 deletions
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12
crypto/dh/dh_check.c
View File

@ -249,6 +249,18 @@ int DH_check_pub_key_ex(const DH *dh, const BIGNUM *pub_key)
*/
int DH_check_pub_key(const DH *dh, const BIGNUM *pub_key, int *ret)
{
/* Don't do any checks at all with an excessively large modulus */
if (BN_num_bits(dh->params.p) > OPENSSL_DH_CHECK_MAX_MODULUS_BITS) {
ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_LARGE);
*ret = DH_MODULUS_TOO_LARGE | DH_CHECK_PUBKEY_INVALID;
return 0;
}
if (dh->params.q != NULL && BN_ucmp(dh->params.p, dh->params.q) < 0) {
*ret |= DH_CHECK_INVALID_Q_VALUE | DH_CHECK_PUBKEY_INVALID;
return 1;
}
return ossl_ffc_validate_public_key(&dh->params, pub_key, ret);
}

3
crypto/dh/dh_err.c
View File

@ -1,6 +1,6 @@
/*
* Generated by util/mkerr.pl DO NOT EDIT
* Copyright 1995-2021 The OpenSSL Project Authors. All Rights Reserved.
* Copyright 1995-2023 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
@ -54,6 +54,7 @@ static const ERR_STRING_DATA DH_str_reasons[] = {
{ERR_PACK(ERR_LIB_DH, 0, DH_R_PARAMETER_ENCODING_ERROR),
"parameter encoding error"},
{ERR_PACK(ERR_LIB_DH, 0, DH_R_PEER_KEY_ERROR), "peer key error"},
{ERR_PACK(ERR_LIB_DH, 0, DH_R_Q_TOO_LARGE), "q too large"},
{ERR_PACK(ERR_LIB_DH, 0, DH_R_SHARED_INFO_ERROR), "shared info error"},
{ERR_PACK(ERR_LIB_DH, 0, DH_R_UNABLE_TO_CHECK_GENERATOR),
"unable to check generator"},

12
crypto/dh/dh_key.c
View File

@ -49,6 +49,12 @@ int ossl_dh_compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
goto err;
}
if (dh->params.q != NULL
&& BN_num_bits(dh->params.q) > OPENSSL_DH_MAX_MODULUS_BITS) {
ERR_raise(ERR_LIB_DH, DH_R_Q_TOO_LARGE);
goto err;
}
if (BN_num_bits(dh->params.p) < DH_MIN_MODULUS_BITS) {
ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_SMALL);
return 0;
@ -267,6 +273,12 @@ static int generate_key(DH *dh)
return 0;
}
if (dh->params.q != NULL
&& BN_num_bits(dh->params.q) > OPENSSL_DH_MAX_MODULUS_BITS) {
ERR_raise(ERR_LIB_DH, DH_R_Q_TOO_LARGE);
return 0;
}
if (BN_num_bits(dh->params.p) < DH_MIN_MODULUS_BITS) {
ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_SMALL);
return 0;

1
crypto/err/openssl.txt
View File

@ -500,6 +500,7 @@ DH_R_NO_PARAMETERS_SET:107:no parameters set
DH_R_NO_PRIVATE_VALUE:100:no private value
DH_R_PARAMETER_ENCODING_ERROR:105:parameter encoding error
DH_R_PEER_KEY_ERROR:111:peer key error
DH_R_Q_TOO_LARGE:130:q too large
DH_R_SHARED_INFO_ERROR:113:shared info error
DH_R_UNABLE_TO_CHECK_GENERATOR:121:unable to check generator
DSA_R_BAD_FFC_PARAMETERS:114:bad ffc parameters

2
include/crypto/dherr.h
View File

@ -1,6 +1,6 @@
/*
* Generated by util/mkerr.pl DO NOT EDIT
* Copyright 2020-2021 The OpenSSL Project Authors. All Rights Reserved.
* Copyright 2020-2023 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

6
include/openssl/dh.h
View File

@ -141,7 +141,7 @@ DECLARE_ASN1_ITEM(DHparams)
# define DH_GENERATOR_3 3
# define DH_GENERATOR_5 5
/* DH_check error codes */
/* DH_check error codes, some of them shared with DH_check_pub_key */
/*
* NB: These values must align with the equivalently named macros in
* internal/ffc.h.
@ -151,10 +151,10 @@ DECLARE_ASN1_ITEM(DHparams)
# define DH_UNABLE_TO_CHECK_GENERATOR 0x04
# define DH_NOT_SUITABLE_GENERATOR 0x08
# define DH_CHECK_Q_NOT_PRIME 0x10
# define DH_CHECK_INVALID_Q_VALUE 0x20
# define DH_CHECK_INVALID_Q_VALUE 0x20 /* +DH_check_pub_key */
# define DH_CHECK_INVALID_J_VALUE 0x40
# define DH_MODULUS_TOO_SMALL 0x80
# define DH_MODULUS_TOO_LARGE 0x100
# define DH_MODULUS_TOO_LARGE 0x100 /* +DH_check_pub_key */
/* DH_check_pub_key error codes */
# define DH_CHECK_PUBKEY_TOO_SMALL 0x01

3
include/openssl/dherr.h
View File

@ -1,6 +1,6 @@
/*
* Generated by util/mkerr.pl DO NOT EDIT
* Copyright 1995-2021 The OpenSSL Project Authors. All Rights Reserved.
* Copyright 1995-2023 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
@ -50,6 +50,7 @@
# define DH_R_NO_PRIVATE_VALUE 100
# define DH_R_PARAMETER_ENCODING_ERROR 105
# define DH_R_PEER_KEY_ERROR 111
# define DH_R_Q_TOO_LARGE 130
# define DH_R_SHARED_INFO_ERROR 113
# define DH_R_UNABLE_TO_CHECK_GENERATOR 121