Support indefinite length BER encodings in PKCS #7

configure.ac

@@ -217,6 +217,7 @@ then
     enable_aeskeywrap=yes
     enable_x963kdf=yes
     enable_scrypt=yes
+    enable_indef=yes
 
     AM_CFLAGS="-DHAVE_AES_DECRYPT $AM_CFLAGS"
 fi
@@ -2662,6 +2663,19 @@ fi
 AM_CONDITIONAL([BUILD_SRP], [test "x$ENABLED_SRP" = "xyes"])
 
 
+# Indefinite length encoded BER message support
+AC_ARG_ENABLE([indef],
+    [AS_HELP_STRING([--enable-indef],[Enable parsing of indefinite length encoded msgs (default: disabled)])],
+    [ ENABLED_BER_INDEF=$enableval ],
+    [ ENABLED_BER_INDEF=no ]
+    )
+
+if test "x$ENABLED_BER_INDEF" = "xyes"
+then
+    AM_CFLAGS="$AM_CFLAGS -DASN_BER_TO_DER"
+fi
+
+
 
 # Small Stack
 AC_ARG_ENABLE([smallstack],
@@ -4247,6 +4261,7 @@ echo "   * SIGNAL:                     $ENABLED_SIGNAL"
 echo "   * ERROR_STRINGS:              $ENABLED_ERROR_STRINGS"
 echo "   * DTLS:                       $ENABLED_DTLS"
 echo "   * SCTP:                       $ENABLED_SCTP"
+echo "   * Indefinite Length:          $ENABLED_BER_INDEF"
 echo "   * Multicast:                  $ENABLED_MCAST"
 echo "   * Old TLS Versions:           $ENABLED_OLD_TLS"
 echo "   * SSL version 3.0:            $ENABLED_SSLV3"

wolfcrypt/src/asn.c

@@ -786,6 +786,128 @@ static word32 SetBitString(word32 len, byte unusedBits, byte* output)
 }
 #endif /* !NO_RSA || HAVE_ECC || HAVE_ED25519 */
 
+#ifdef ASN_BER_TO_DER
+/* Convert a BER encoding with indefinite length items to DER.
+ *
+ * ber     BER encoded data.
+ * length  Length of BER encoded data.
+ * der     Buffer to hold DER encoded version of data.
+ *         NULL indicates only the length is required.
+ * returns the length of the DER data on success, ASN_PARSE_E if the BER data is
+ *         invalid and BAD_FUNC_ARG if ber is NULL.
+ */
+int wc_BerToDer(byte* ber, word32 length, byte* der)
+{
+    int ret;
+    word32 i, j, k;
+    int len, l;
+    int indef;
+    int depth = 1;
+    word32 cnt;
+    byte lenBytes[4];
+
+    if (ber == NULL)
+        return BAD_FUNC_ARG;
+
+    for (i = 0, j = 0; i < length; ) {
+        if (i + 1 >= length)
+            return ASN_PARSE_E;
+
+        if (ber[i] == 0 && ber[i+1] == 0) {
+            if (--depth == 0)
+                break;
+
+            i += 2;
+            continue;
+        }
+
+        indef = ber[i+1] == 0x80;
+        if (indef && ber[i] < 0x40 && ber[i] != 0x30 && ber[i] != 0x31) {
+            if (der != NULL)
+                der[j] = ber[i] & 0x1f;
+            i++; j++;
+            i++;
+
+            if (i + 1 >= length)
+                return ASN_PARSE_E;
+
+            len = 0;
+            k = i;
+            while (ber[k] != 0x00) {
+                k++;
+                ret = GetLength(ber, &k, &l, length);
+                if (ret < 0)
+                    return ASN_PARSE_E;
+                k += l;
+                len += l;
+
+                if (k + 1 >= length)
+                    return ASN_PARSE_E;
+            }
+
+            if (der == NULL) {
+                j += SetLength(len, lenBytes);
+                j += len;
+            }
+            else {
+                j += SetLength(len, der + j);
+                k = i;
+                while (ber[k] != 0x00) {
+                    k++;
+                    ret = GetLength(ber, &k, &l, length);
+                    if (ret < 0)
+                        return ASN_PARSE_E;
+                    XMEMCPY(der + j, ber + k, l);
+                    k += l; j += l;
+                }
+            }
+            i = k + 2;
+
+            continue;
+        }
+
+        if (der != NULL)
+            der[j] = ber[i];
+        i++; j++;
+
+        cnt = i;
+        ret = GetLength(ber, &cnt, &len, length);
+        if (ret < 0)
+            return ASN_PARSE_E;
+        cnt -= i;
+        if (der != NULL) {
+            for (k = 0; k < cnt; k++)
+                der[j + k] = ber[i + k];
+        }
+        i += cnt; j += cnt;
+        if (cnt == 0) {
+            i++;
+            len = wc_BerToDer(ber + i, length - i, NULL);
+            if (len < 0)
+                return len;
+            if (der != NULL)
+                j += SetLength(len, der + j);
+            else
+                j += SetLength(len, lenBytes);
+        }
+
+        if (!indef) {
+            if (i + len > length)
+                return ASN_PARSE_E;
+
+            if (der != NULL)
+                XMEMCPY(der + j, ber + i, len);
+            i += len;
+            j += len;
+        }
+        else
+            depth++;
+    }
+
+    return j;
+}
+#endif
+
 #if defined(WOLFSSL_CERT_GEN) || defined(WOLFSSL_KEY_GEN)
 
 #if (!defined(NO_RSA) && !defined(HAVE_USER_RSA)) || \

wolfcrypt/src/error.c

@@ -449,6 +449,9 @@ const char* wc_GetErrorString(int error)
     case PRIME_GEN_E:
         return "Unable to find a prime for RSA key";
 
+    case BER_INDEF_E:
+        return "Unable to decode an indefinite length encoded message";
+
     default:
         return "unknown error number";
 

wolfcrypt/src/pkcs7.c

@@ -338,6 +338,11 @@ void wc_PKCS7_Free(PKCS7* pkcs7)
         return;
 
     wc_PKCS7_FreeDecodedAttrib(pkcs7->decodedAttrib, pkcs7->heap);
+
+#ifdef ASN_BER_TO_DER
+    if (pkcs7->der != NULL)
+        XFREE(pkcs7->der, pkcs7->heap, DYNAMIC_TYPE_PKCS7);
+#endif
 }
 
 
@@ -1849,6 +1854,28 @@ int wc_PKCS7_VerifySignedData(PKCS7* pkcs7, byte* pkiMsg, word32 pkiMsgSz)
     if (GetSequence(pkiMsg, &idx, &length, pkiMsgSz) < 0)
         return ASN_PARSE_E;
 
+    if (length == 0 && pkiMsg[idx-1] == 0x80) {
+#ifdef ASN_BER_TO_DER
+        int len;
+
+        len = wc_BerToDer(pkiMsg, pkiMsgSz, NULL);
+        if (len < 0)
+            return len;
+        pkcs7->der = XMALLOC(len, pkcs7->heap, DYNAMIC_TYPE_PKCS7);
+        if (pkcs7->der == NULL)
+            return MEMORY_E;
+        wc_BerToDer(pkiMsg, pkiMsgSz, pkcs7->der);
+
+        pkiMsg = pkcs7->der;
+        pkiMsgSz = len;
+        idx = 0;
+        if (GetSequence(pkiMsg, &idx, &length, pkiMsgSz) < 0)
+            return ASN_PARSE_E;
+#else
+        return BER_INDEF_E;
+#endif
+    }
+
     /* Get the contentInfo contentType */
     if (wc_GetContentType(pkiMsg, &idx, &contentType, pkiMsgSz) < 0)
         return ASN_PARSE_E;
@@ -4299,6 +4326,7 @@ WOLFSSL_API int wc_PKCS7_DecodeEnvelopedData(PKCS7* pkcs7, byte* pkiMsg,
     int encryptedContentSz;
     byte padLen;
     byte* encryptedContent = NULL;
+    int explicitOctet;
 
     if (pkcs7 == NULL || pkcs7->singleCert == NULL ||
         pkcs7->singleCertSz == 0 || pkcs7->privateKey == NULL ||
@@ -4313,6 +4341,28 @@ WOLFSSL_API int wc_PKCS7_DecodeEnvelopedData(PKCS7* pkcs7, byte* pkiMsg,
     if (GetSequence(pkiMsg, &idx, &length, pkiMsgSz) < 0)
         return ASN_PARSE_E;
 
+    if (length == 0 && pkiMsg[idx-1] == 0x80) {
+#ifdef ASN_BER_TO_DER
+        int len;
+
+        len = wc_BerToDer(pkiMsg, pkiMsgSz, NULL);
+        if (len < 0)
+            return len;
+        pkcs7->der = XMALLOC(len, pkcs7->heap, DYNAMIC_TYPE_PKCS7);
+        if (pkcs7->der == NULL)
+            return MEMORY_E;
+        wc_BerToDer(pkiMsg, pkiMsgSz, pkcs7->der);
+
+        pkiMsg = pkcs7->der;
+        pkiMsgSz = len;
+        idx = 0;
+        if (GetSequence(pkiMsg, &idx, &length, pkiMsgSz) < 0)
+            return ASN_PARSE_E;
+#else
+        return BER_INDEF_E;
+#endif
+    }
+
     if (wc_GetContentType(pkiMsg, &idx, &contentType, pkiMsgSz) < 0)
         return ASN_PARSE_E;
 
@@ -4435,8 +4485,27 @@ WOLFSSL_API int wc_PKCS7_DecodeEnvelopedData(PKCS7* pkcs7, byte* pkiMsg,
     XMEMCPY(tmpIv, &pkiMsg[idx], length);
     idx += length;
 
+    explicitOctet = pkiMsg[idx] == (ASN_CONTEXT_SPECIFIC | ASN_CONSTRUCTED | 0);
+
     /* read encryptedContent, cont[0] */
-    if (pkiMsg[idx++] != (ASN_CONTEXT_SPECIFIC | 0)) {
+    if (pkiMsg[idx] != (ASN_CONTEXT_SPECIFIC | 0) &&
+        pkiMsg[idx] != (ASN_CONTEXT_SPECIFIC | ASN_CONSTRUCTED | 0)) {
+#ifdef WOLFSSL_SMALL_STACK
+        XFREE(decryptedKey, NULL, DYNAMIC_TYPE_PKCS7);
+#endif
+        return ASN_PARSE_E;
+    }
+    idx++;
+
+    if (GetLength(pkiMsg, &idx, &encryptedContentSz, pkiMsgSz) <= 0) {
+#ifdef WOLFSSL_SMALL_STACK
+        XFREE(decryptedKey, NULL, DYNAMIC_TYPE_PKCS7);
+#endif
+        return ASN_PARSE_E;
+    }
+
+    if (explicitOctet) {
+        if (pkiMsg[idx++] != ASN_OCTET_STRING) {
 #ifdef WOLFSSL_SMALL_STACK
             XFREE(decryptedKey, NULL, DYNAMIC_TYPE_PKCS7);
 #endif
@@ -4449,6 +4518,7 @@ WOLFSSL_API int wc_PKCS7_DecodeEnvelopedData(PKCS7* pkcs7, byte* pkiMsg,
 #endif
             return ASN_PARSE_E;
         }
+    }
 
     encryptedContent = (byte*)XMALLOC(encryptedContentSz, pkcs7->heap,
                                                        DYNAMIC_TYPE_PKCS7);

wolfcrypt/test/test.c

@@ -16702,6 +16702,9 @@ int pkcs7encrypted_test(void)
         pkcs7.unprotectedAttribs   = testVectors[i].attribs;
         pkcs7.unprotectedAttribsSz = testVectors[i].attribsSz;
         pkcs7.heap                 = HEAP_HINT;
+#ifdef ASN_BER_TO_DER
+        pkcs7.der                  = NULL;
+#endif
 
         /* encode encryptedData */
         encryptedSz = wc_PKCS7_EncodeEncryptedData(&pkcs7, encrypted,

wolfssl/wolfcrypt/asn.h

@@ -765,6 +765,8 @@ struct TrustedPeerCert {
     #define WOLFSSL_ASN_API WOLFSSL_LOCAL
 #endif
 
+WOLFSSL_ASN_API int wc_BerToDer(byte* ber, word32 length, byte* der);
+
 WOLFSSL_ASN_API void FreeAltNames(DNS_entry*, void*);
 #ifndef IGNORE_NAME_CONSTRAINTS
     WOLFSSL_ASN_API void FreeNameSubtrees(Base_entry*, void*);

wolfssl/wolfcrypt/error-crypt.h

@@ -198,7 +198,9 @@ enum {
     PSS_SALTLEN_E       = -250,  /* PSS length of salt is to long for hash */
     PRIME_GEN_E         = -251,  /* Failure finding a prime. */
 
-    WC_LAST_E           = -251,  /* Update this to indicate last error */
+    BER_INDEF_E         = -252,  /* Cannot decode indefinite length BER. */
+
+    WC_LAST_E           = -252,  /* Update this to indicate last error */
     MIN_CODE_E          = -300   /* errors -101 - -299 */
 
     /* add new companion error id strings for any new error codes

wolfssl/wolfcrypt/pkcs7.h

@@ -100,6 +100,9 @@ typedef struct PKCS7 {
     byte*  issuer;                /* issuer name of singleCert            */
     byte*  privateKey;            /* private key, DER, not owner          */
     void*  heap;                  /* heap hint for dynamic memory         */
+#ifdef ASN_BER_TO_DER
+    byte*  der;                   /* DER encoded version of message       */
+#endif
     byte*  cert[MAX_PKCS7_CERTS];
 
     /* Encrypted-data Content Type */