From 246b05d1f3d4b4b5d131bf2fc345d1e894fc3f32 Mon Sep 17 00:00:00 2001
From: lanming1120 <lanming1120@126.com>
Date: Tue, 5 Dec 2023 19:53:02 +0800
Subject: [PATCH] Make DH_check_pub_key() and DH_generate_key() safer yet

---
 Cryptlib/Include/openssl/dh.h         |  7 +++++--
 Cryptlib/OpenSSL/crypto/dh/dh_check.c | 13 +++++++++++++
 Cryptlib/OpenSSL/crypto/dh/dh_err.c   |  2 ++
 Cryptlib/OpenSSL/crypto/dh/dh_key.c   | 12 ++++++++++++
 4 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/Cryptlib/Include/openssl/dh.h b/Cryptlib/Include/openssl/dh.h
index 6488879..890f007 100644
--- a/Cryptlib/Include/openssl/dh.h
+++ b/Cryptlib/Include/openssl/dh.h
@@ -162,14 +162,15 @@ struct dh_st {
 /* #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 */
 # define DH_CHECK_P_NOT_PRIME            0x01
 # define DH_CHECK_P_NOT_SAFE_PRIME       0x02
 # 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_LARGE            0x100
 
 /* DH_check_pub_key error codes */
 # define DH_CHECK_PUBKEY_TOO_SMALL       0x01
@@ -389,7 +390,9 @@ void ERR_load_DH_strings(void);
 # define DH_R_NO_PRIVATE_VALUE                            100
 # define DH_R_PARAMETER_ENCODING_ERROR                    105
 # define DH_R_PEER_KEY_ERROR                              113
+# define DH_R_Q_TOO_LARGE                                 130
 # define DH_R_SHARED_INFO_ERROR                           114
+# define DH_F_DH_CHECK_PUB_KEY                            128
 
 #ifdef  __cplusplus
 }
diff --git a/Cryptlib/OpenSSL/crypto/dh/dh_check.c b/Cryptlib/OpenSSL/crypto/dh/dh_check.c
index 9f3b174..30b2d6c 100644
--- a/Cryptlib/OpenSSL/crypto/dh/dh_check.c
+++ b/Cryptlib/OpenSSL/crypto/dh/dh_check.c
@@ -162,6 +162,19 @@ int DH_check_pub_key(const DH *dh, const BIGNUM *pub_key, int *ret)
     BN_CTX *ctx = NULL;
 
     *ret = 0;
+
+    /* Don't do any checks at all with an excessively large modulus */
+    if (BN_num_bits(dh->p) > OPENSSL_DH_CHECK_MAX_MODULUS_BITS) {
+        DHerr(DH_F_DH_CHECK_PUB_KEY, DH_R_MODULUS_TOO_LARGE);
+        *ret = DH_MODULUS_TOO_LARGE | DH_CHECK_PUBKEY_INVALID;
+        return 0;
+    }
+
+    if (dh->q != NULL && BN_ucmp(dh->p, dh->q) < 0) {
+        *ret |= DH_CHECK_INVALID_Q_VALUE | DH_CHECK_PUBKEY_INVALID;
+        return 1;
+    }
+
     ctx = BN_CTX_new();
     if (ctx == NULL)
         goto err;
diff --git a/Cryptlib/OpenSSL/crypto/dh/dh_err.c b/Cryptlib/OpenSSL/crypto/dh/dh_err.c
index b890cca..7615558 100644
--- a/Cryptlib/OpenSSL/crypto/dh/dh_err.c
+++ b/Cryptlib/OpenSSL/crypto/dh/dh_err.c
@@ -73,6 +73,7 @@ static ERR_STRING_DATA DH_str_functs[] = {
     {ERR_FUNC(DH_F_COMPUTE_KEY), "COMPUTE_KEY"},
     {ERR_FUNC(DH_F_DHPARAMS_PRINT_FP), "DHparams_print_fp"},
     {ERR_FUNC(DH_F_DH_BUILTIN_GENPARAMS), "DH_BUILTIN_GENPARAMS"},
+    {ERR_FUNC(DH_F_DH_CHECK_PUB_KEY), "DH_check_pub_key"},
     {ERR_FUNC(DH_F_DH_CMS_DECRYPT), "DH_CMS_DECRYPT"},
     {ERR_FUNC(DH_F_DH_CMS_SET_PEERKEY), "DH_CMS_SET_PEERKEY"},
     {ERR_FUNC(DH_F_DH_CMS_SET_SHARED_INFO), "DH_CMS_SET_SHARED_INFO"},
@@ -108,6 +109,7 @@ static ERR_STRING_DATA DH_str_reasons[] = {
     {ERR_REASON(DH_R_NO_PRIVATE_VALUE), "no private value"},
     {ERR_REASON(DH_R_PARAMETER_ENCODING_ERROR), "parameter encoding error"},
     {ERR_REASON(DH_R_PEER_KEY_ERROR), "peer key error"},
+    {ERR_REASON(DH_R_Q_TOO_LARGE), "q too large"},
     {ERR_REASON(DH_R_SHARED_INFO_ERROR), "shared info error"},
     {0, NULL}
 };
diff --git a/Cryptlib/OpenSSL/crypto/dh/dh_key.c b/Cryptlib/OpenSSL/crypto/dh/dh_key.c
index f235e0d..d66de13 100644
--- a/Cryptlib/OpenSSL/crypto/dh/dh_key.c
+++ b/Cryptlib/OpenSSL/crypto/dh/dh_key.c
@@ -134,6 +134,12 @@ static int generate_key(DH *dh)
     BN_MONT_CTX *mont = NULL;
     BIGNUM *pub_key = NULL, *priv_key = NULL;
 
+   if (dh->q != NULL
+        && BN_num_bits(dh->q) > OPENSSL_DH_MAX_MODULUS_BITS) {
+        DHerr(DH_F_GENERATE_KEY, DH_R_Q_TOO_LARGE);
+        return 0;
+    }
+
     if (BN_num_bits(dh->p) > OPENSSL_DH_MAX_MODULUS_BITS) {
         DHerr(DH_F_GENERATE_KEY, DH_R_MODULUS_TOO_LARGE);
         return 0;
@@ -218,6 +224,12 @@ static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
     int ret = -1;
     int check_result;
 
+   if (dh->q != NULL
+        && BN_num_bits(dh->q) > OPENSSL_DH_MAX_MODULUS_BITS) {
+        DHerr(DH_F_COMPUTE_KEY, DH_R_Q_TOO_LARGE);
+        goto err;
+    }
+
     if (BN_num_bits(dh->p) > OPENSSL_DH_MAX_MODULUS_BITS) {
         DHerr(DH_F_COMPUTE_KEY, DH_R_MODULUS_TOO_LARGE);
         goto err;
-- 
2.27.0

