Introduce limits to prevent malicious keys being able to

cause a denial of service.  (CVE-2006-2940)
[Steve Henson, Bodo Moeller]

3 files changed, 59 insertions, 2 deletions

diff --git a/crypto/ec/ec.h b/crypto/ec/ec.h
index 8da8e34339..2348e4c4cb 100644
--- a/crypto/ec/ec.h
+++ b/crypto/ec/ec.h
@@ -96,6 +96,11 @@ extern "C" {
 # endif
 #endif
 
+  
+#ifndef OPENSSL_ECC_MAX_FIELD_BITS
+# define OPENSSL_ECC_MAX_FIELD_BITS 661
+#endif
+
 /** Enum for the point conversion form as defined in X9.62 (ECDSA)
  *  for the encoding of a elliptic curve point (x,y) */
 typedef enum {
@@ -1049,22 +1054,25 @@ void ERR_load_EC_strings(void);
 #define EC_R_ASN1_UNKNOWN_FIELD				 116
 #define EC_R_BUFFER_TOO_SMALL				 100
 #define EC_R_D2I_ECPKPARAMETERS_FAILURE			 117
-#define EC_R_DECODE_ERROR				 137
+#define EC_R_DECODE_ERROR				 142
 #define EC_R_DISCRIMINANT_IS_ZERO			 118
 #define EC_R_EC_GROUP_NEW_BY_NAME_FAILURE		 119
+#define EC_R_FIELD_TOO_LARGE				 138
 #define EC_R_GROUP2PKPARAMETERS_FAILURE			 120
 #define EC_R_I2D_ECPKPARAMETERS_FAILURE			 121
 #define EC_R_INCOMPATIBLE_OBJECTS			 101
 #define EC_R_INVALID_ARGUMENT				 112
 #define EC_R_INVALID_COMPRESSED_POINT			 110
 #define EC_R_INVALID_COMPRESSION_BIT			 109
-#define EC_R_INVALID_CURVE				 132
+#define EC_R_INVALID_CURVE				 141
 #define EC_R_INVALID_DIGEST_TYPE			 138
 #define EC_R_INVALID_ENCODING				 102
 #define EC_R_INVALID_FIELD				 103
 #define EC_R_INVALID_FORM				 104
 #define EC_R_INVALID_GROUP_ORDER			 122
+#define EC_R_INVALID_PENTANOMIAL_BASIS			 132
 #define EC_R_INVALID_PRIVATE_KEY			 123
+#define EC_R_INVALID_TRINOMIAL_BASIS			 137
 #define EC_R_KEYS_NOT_SET				 140
 #define EC_R_MISSING_PARAMETERS				 124
 #define EC_R_MISSING_PRIVATE_KEY			 125
diff --git a/crypto/ec/ec_asn1.c b/crypto/ec/ec_asn1.c
index dec913b8ad..66ef129293 100644
--- a/crypto/ec/ec_asn1.c
+++ b/crypto/ec/ec_asn1.c
@@ -741,6 +741,7 @@ static EC_GROUP *ec_asn1_parameters2group(const ECPARAMETERS *params)
 	EC_GROUP		*ret = NULL;
 	BIGNUM			*p = NULL, *a = NULL, *b = NULL;
 	EC_POINT		*point=NULL;
+	long    		field_bits;
 
 	if (!params->fieldID || !params->fieldID->fieldType || 
 	    !params->fieldID->p.ptr)
@@ -779,6 +780,13 @@ static EC_GROUP *ec_asn1_parameters2group(const ECPARAMETERS *params)
 
 		char_two = params->fieldID->p.char_two;
 
+		field_bits = char_two->m;
+		if (field_bits > OPENSSL_ECC_MAX_FIELD_BITS)
+			{
+			ECerr(EC_F_EC_ASN1_PARAMETERS2GROUP, EC_R_FIELD_TOO_LARGE);
+			goto err;
+			}
+
 		if ((p = BN_new()) == NULL)
 			{
 			ECerr(EC_F_EC_ASN1_PARAMETERS2GROUP, ERR_R_MALLOC_FAILURE);
@@ -799,6 +807,13 @@ static EC_GROUP *ec_asn1_parameters2group(const ECPARAMETERS *params)
 				}
 
 			tmp_long = ASN1_INTEGER_get(char_two->p.tpBasis);
+
+			if (!(char_two->m > tmp_long && tmp_long > 0))
+				{
+				ECerr(EC_F_EC_ASN1_PARAMETERS2GROUP, EC_R_INVALID_TRINOMIAL_BASIS);
+				goto err;
+				}
+			
 			/* create the polynomial */
 			if (!BN_set_bit(p, (int)char_two->m))
 				goto err;
@@ -817,6 +832,13 @@ static EC_GROUP *ec_asn1_parameters2group(const ECPARAMETERS *params)
 				ECerr(EC_F_EC_ASN1_PARAMETERS2GROUP, EC_R_ASN1_ERROR);
 				goto err;
 				}
+
+			if (!(char_two->m > penta->k3 && penta->k3 > penta->k2 && penta->k2 > penta->k1 && penta->k1 > 0))
+				{
+				ECerr(EC_F_EC_ASN1_PARAMETERS2GROUP, EC_R_INVALID_PENTANOMIAL_BASIS);
+				goto err;
+				}
+			
 			/* create the polynomial */
 			if (!BN_set_bit(p, (int)char_two->m)) goto err;
 			if (!BN_set_bit(p, (int)penta->k1)) goto err;
@@ -853,6 +875,20 @@ static EC_GROUP *ec_asn1_parameters2group(const ECPARAMETERS *params)
 			ECerr(EC_F_EC_ASN1_PARAMETERS2GROUP, ERR_R_ASN1_LIB);
 			goto err;
 			}
+
+		if (BN_is_negative(p) || BN_is_zero(p))
+			{
+			ECerr(EC_F_EC_ASN1_PARAMETERS2GROUP, EC_R_INVALID_FIELD);
+			goto err;
+			}
+
+		field_bits = BN_num_bits(p);
+		if (field_bits > OPENSSL_ECC_MAX_FIELD_BITS)
+			{
+			ECerr(EC_F_EC_ASN1_PARAMETERS2GROUP, EC_R_FIELD_TOO_LARGE);
+			goto err;
+			}
+
 		/* create the EC_GROUP structure */
 		ret = EC_GROUP_new_curve_GFp(p, a, b, NULL);
 		}
@@ -910,6 +946,16 @@ static EC_GROUP *ec_asn1_parameters2group(const ECPARAMETERS *params)
 		ECerr(EC_F_EC_ASN1_PARAMETERS2GROUP, ERR_R_ASN1_LIB);
 		goto err;
 		}
+	if (BN_is_negative(a) || BN_is_zero(a))
+		{
+		ECerr(EC_F_EC_ASN1_PARAMETERS2GROUP, EC_R_INVALID_GROUP_ORDER);
+		goto err;
+		}
+	if (BN_num_bits(a) > (int)field_bits + 1) /* Hasse bound */
+		{
+		ECerr(EC_F_EC_ASN1_PARAMETERS2GROUP, EC_R_INVALID_GROUP_ORDER);
+		goto err;
+		}
 	
 	/* extract the cofactor (optional) */
 	if (params->cofactor == NULL)
diff --git a/crypto/ec/ec_err.c b/crypto/ec/ec_err.c
index 8633760fde..8db5195bcd 100644
--- a/crypto/ec/ec_err.c
+++ b/crypto/ec/ec_err.c
@@ -204,6 +204,7 @@ static ERR_STRING_DATA EC_str_reasons[]=
 {ERR_REASON(EC_R_DECODE_ERROR)           ,"decode error"},
 {ERR_REASON(EC_R_DISCRIMINANT_IS_ZERO)   ,"discriminant is zero"},
 {ERR_REASON(EC_R_EC_GROUP_NEW_BY_NAME_FAILURE),"ec group new by name failure"},
+{ERR_REASON(EC_R_FIELD_TOO_LARGE)        ,"field too large"},
 {ERR_REASON(EC_R_GROUP2PKPARAMETERS_FAILURE),"group2pkparameters failure"},
 {ERR_REASON(EC_R_I2D_ECPKPARAMETERS_FAILURE),"i2d ecpkparameters failure"},
 {ERR_REASON(EC_R_INCOMPATIBLE_OBJECTS)   ,"incompatible objects"},
@@ -216,7 +217,9 @@ static ERR_STRING_DATA EC_str_reasons[]=
 {ERR_REASON(EC_R_INVALID_FIELD)          ,"invalid field"},
 {ERR_REASON(EC_R_INVALID_FORM)           ,"invalid form"},
 {ERR_REASON(EC_R_INVALID_GROUP_ORDER)    ,"invalid group order"},
+{ERR_REASON(EC_R_INVALID_PENTANOMIAL_BASIS),"invalid pentanomial basis"},
 {ERR_REASON(EC_R_INVALID_PRIVATE_KEY)    ,"invalid private key"},
+{ERR_REASON(EC_R_INVALID_TRINOMIAL_BASIS),"invalid trinomial basis"},
 {ERR_REASON(EC_R_KEYS_NOT_SET)           ,"keys not set"},
 {ERR_REASON(EC_R_MISSING_PARAMETERS)     ,"missing parameters"},
 {ERR_REASON(EC_R_MISSING_PRIVATE_KEY)    ,"missing private key"},