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 +786,211 @@ 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.
+ * berSz  Length of BER encoded data.
+ * der    Buffer to hold DER encoded version of data.
+ *        NULL indicates only the length is required.
+ * derSz  The size of the buffer to hold the DER encoded data.
+ *        Will be set if der is NULL, otherwise the value is checked as der is
+ *        filled.
+ * returns ASN_PARSE_E if the BER data is invalid and BAD_FUNC_ARG if ber or
+ * derSz are NULL.
+ */
+int wc_BerToDer(const byte* ber, word32 berSz, byte* der, word32* derSz)
+{
+    int ret;
+    word32 i, j, k;
+    int len, l;
+    int indef;
+    int depth = 0;
+    byte type;
+    word32 cnt, sz;
+    word32 outSz;
+    byte lenBytes[4];
+
+    if (ber == NULL || derSz == NULL)
+        return BAD_FUNC_ARG;
+
+    outSz = *derSz;
+
+    for (i = 0, j = 0; i < berSz; ) {
+        /* Check that there is data for an ASN item to parse. */
+        if (i + 2 > berSz)
+            return ASN_PARSE_E;
+
+        /* End Of Content (EOC) mark end of indefinite length items.
+         * EOCs are not encoded in DER.
+         * Keep track of no. indefinite length items that have not been
+         * terminated in depth.
+         */
+        if (ber[i] == 0 && ber[i+1] == 0) {
+            if (depth == 0)
+                break;
+            if (--depth == 0)
+                break;
+
+            i += 2;
+            continue;
+        }
+
+        /* Indefinite length is encoded as: 0x80 */
+        type = ber[i];
+        indef = ber[i+1] == ASN_INDEF_LENGTH;
+        if (indef && (type & 0xC0) == 0 &&
+                                   ber[i] != (ASN_SEQUENCE | ASN_CONSTRUCTED) &&
+                                   ber[i] != (ASN_SET      | ASN_CONSTRUCTED)) {
+            /* Indefinite length OCTET STRING or other simple type.
+             * Put all the data into one entry.
+             */
+
+            /* Type no longer constructed. */
+            type &= ~ASN_CONSTRUCTED;
+            if (der != NULL) {
+                /* Ensure space for type. */
+                if (j + 1 >= outSz)
+                    return BUFFER_E;
+                der[j] = type;
+            }
+            i++; j++;
+            /* Skip indefinite length. */
+            i++;
+
+            /* There must be further ASN1 items to combine. */
+            if (i + 2 > berSz)
+                return ASN_PARSE_E;
+
+            /* Calculate length of combined data. */
+            len = 0;
+            k = i;
+            while (ber[k] != 0x00) {
+                /* Each ASN item must be the same type as the constructed. */
+                if (ber[k] != type)
+                    return ASN_PARSE_E;
+                k++;
+
+                ret = GetLength(ber, &k, &l, berSz);
+                if (ret < 0)
+                    return ASN_PARSE_E;
+                k += l;
+                len += l;
+
+                /* Must at least have terminating EOC. */
+                if (k + 2 > berSz)
+                    return ASN_PARSE_E;
+            }
+            /* Ensure a valid EOC ASN item. */
+            if (ber[k+1] != 0x00)
+                return ASN_PARSE_E;
+
+            if (der == NULL) {
+                /* Add length of ASN item length encoding and data. */
+                j += SetLength(len, lenBytes);
+                j += len;
+            }
+            else {
+                /* Check space for encoded length. */
+                if (SetLength(len, lenBytes) > outSz - j)
+                    return BUFFER_E;
+                /* Encode new length. */
+                j += SetLength(len, der + j);
+
+                /* Encode data in single item. */
+                k = i;
+                while (ber[k] != 0x00) {
+                    /* Skip ASN type. */
+                    k++;
+
+                    /* Find length of data in ASN item. */
+                    ret = GetLength(ber, &k, &l, berSz);
+                    if (ret < 0)
+                        return ASN_PARSE_E;
+
+                    /* Ensure space for data and copy in. */
+                    if (j + l > outSz)
+                        return BUFFER_E;
+                    XMEMCPY(der + j, ber + k, l);
+                    k += l; j += l;
+                }
+            }
+            /* Continue conversion after EOC. */
+            i = k + 2;
+
+            continue;
+        }
+
+        if (der != NULL) {
+            /* Ensure space for type and at least one byte of length. */
+            if (j + 1 >= outSz)
+                return BUFFER_E;
+            /* Put in type. */
+            der[j] = ber[i];
+        }
+        i++; j++;
+
+        if (indef) {
+            /* Skip indefinite length. */
+            i++;
+            /* Calculate the size of the data inside constructed. */
+            ret = wc_BerToDer(ber + i, berSz - i, NULL, &sz);
+            if (ret != LENGTH_ONLY_E)
+                return ret;
+
+            if (der != NULL) {
+                /* Ensure space for encoded length. */
+                if (SetLength(sz, lenBytes) > outSz - j)
+                    return BUFFER_E;
+                /* Encode real length. */
+                j += SetLength(sz, der + j);
+            }
+            else {
+                /* Add size of encoded length. */
+                j += SetLength(sz, lenBytes);
+            }
+
+            /* Another EOC to find. */
+            depth++;
+        }
+        else {
+            /* Get the size of the encode length and length value. */
+            cnt = i;
+            ret = GetLength(ber, &cnt, &len, berSz);
+            if (ret < 0)
+                return ASN_PARSE_E;
+            cnt -= i;
+
+            /* Check there is enough data to copy out. */
+            if (i + cnt + len > berSz)
+                return ASN_PARSE_E;
+
+            if (der != NULL) {
+                /* Ensure space in DER buffer. */
+                if (j + cnt + len > outSz)
+                    return BUFFER_E;
+                /* Copy length and data into DER buffer. */
+                XMEMCPY(der + j, ber + i, cnt + len);
+            }
+            /* Continue conversion after this ASN item. */
+            i += cnt + len;
+            j += cnt + len;
+        }
+    }
+
+    if (depth >= 1)
+        return ASN_PARSE_E;
+
+    /* Return length if no buffer to write to. */
+    if (der == NULL) {
+        *derSz = j;
+        return LENGTH_ONLY_E;
+    }
+
+    return 0;
+}
+#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";