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From ddeb4b6c6d527e54ce9a99cba785c0f7776e54b6 Mon Sep 17 00:00:00 2001
From: Richard Levitte <levitte@openssl.org>
Date: Fri, 20 Oct 2023 09:18:19 +0200
Subject: [PATCH] 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)
---
crypto/dh/dh_check.c | 12 ++++++++++++
crypto/dh/dh_err.c | 3 ++-
crypto/dh/dh_key.c | 12 ++++++++++++
crypto/err/openssl.txt | 1 +
include/crypto/dherr.h | 2 +-
include/openssl/dh.h | 6 +++---
include/openssl/dherr.h | 3 ++-
7 files changed, 33 insertions(+), 6 deletions(-)
diff --git a/crypto/dh/dh_check.c b/crypto/dh/dh_check.c
index 7ba2beae7fd6b..e20eb62081c5e 100644
--- crypto/dh/dh_check.c.orig
+++ crypto/dh/dh_check.c
@@ -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);
}
diff --git a/crypto/dh/dh_err.c b/crypto/dh/dh_err.c
index 4152397426cc9..f76ac0dd1463f 100644
--- crypto/dh/dh_err.c.orig
+++ crypto/dh/dh_err.c
@@ -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"},
diff --git a/crypto/dh/dh_key.c b/crypto/dh/dh_key.c
index d84ea99241b9e..afc49f5cdc87d 100644
--- crypto/dh/dh_key.c.orig
+++ crypto/dh/dh_key.c
@@ -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;
diff --git a/crypto/err/openssl.txt b/crypto/err/openssl.txt
index a1e6bbb617fcb..69e4f61aa1801 100644
--- crypto/err/openssl.txt.orig
+++ crypto/err/openssl.txt
@@ -513,6 +513,7 @@ 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
diff --git a/include/crypto/dherr.h b/include/crypto/dherr.h
index bb24d131eb887..519327f795742 100644
--- include/crypto/dherr.h.orig
+++ include/crypto/dherr.h
@@ -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
diff --git a/include/openssl/dh.h b/include/openssl/dh.h
index 8bc17448a0817..f1c0ed06b375a 100644
--- include/openssl/dh.h.orig
+++ include/openssl/dh.h
@@ -144,7 +144,7 @@ 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.
@@ -154,10 +154,10 @@ 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
diff --git a/include/openssl/dherr.h b/include/openssl/dherr.h
index 5d2a762a96f8c..074a70145f9f5 100644
--- include/openssl/dherr.h.orig
+++ include/openssl/dherr.h
@@ -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
|
