util/TLSProxy/Record.pm

   1 # Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
   2 #
   3 # Licensed under the OpenSSL license (the "License").  You may not use
   4 # this file except in compliance with the License.  You can obtain a copy
   5 # in the file LICENSE in the source distribution or at
   6 # https://www.openssl.org/source/license.html
   7
   8 use strict;
   9
  10 use TLSProxy::Proxy;
  11
  12 package TLSProxy::Record;
  13
  14 my $server_encrypting = 0;
  15 my $client_encrypting = 0;
  16 my $etm = 0;
  17
  18 use constant TLS_RECORD_HEADER_LENGTH => 5;
  19
  20 #Record types
  21 use constant {
  22     RT_APPLICATION_DATA => 23,
  23     RT_HANDSHAKE => 22,
  24     RT_ALERT => 21,
  25     RT_CCS => 20,
  26     RT_UNKNOWN => 100
  27 };
  28
  29 my %record_type = (
  30     RT_APPLICATION_DATA, "APPLICATION DATA",
  31     RT_HANDSHAKE, "HANDSHAKE",
  32     RT_ALERT, "ALERT",
  33     RT_CCS, "CCS",
  34     RT_UNKNOWN, "UNKNOWN"
  35 );
  36
  37 use constant {
  38     VERS_TLS_1_4 => 0x0305,
  39     VERS_TLS_1_3_DRAFT => 0x7f13,
  40     VERS_TLS_1_3 => 0x0304,
  41     VERS_TLS_1_2 => 0x0303,
  42     VERS_TLS_1_1 => 0x0302,
  43     VERS_TLS_1_0 => 0x0301,
  44     VERS_SSL_3_0 => 0x0300,
  45     VERS_SSL_LT_3_0 => 0x02ff
  46 };
  47
  48 my %tls_version = (
  49     VERS_TLS_1_3, "TLS1.3",
  50     VERS_TLS_1_2, "TLS1.2",
  51     VERS_TLS_1_1, "TLS1.1",
  52     VERS_TLS_1_0, "TLS1.0",
  53     VERS_SSL_3_0, "SSL3",
  54     VERS_SSL_LT_3_0, "SSL<3"
  55 );
  56
  57 #Class method to extract records from a packet of data
  58 sub get_records
  59 {
  60     my $class = shift;
  61     my $server = shift;
  62     my $flight = shift;
  63     my $packet = shift;
  64     my @record_list = ();
  65     my @message_list = ();
  66     my $data;
  67     my $content_type;
  68     my $version;
  69     my $len;
  70     my $len_real;
  71     my $decrypt_len;
  72
  73     my $recnum = 1;
  74     while (length ($packet) > 0) {
  75         print " Record $recnum";
  76         if ($server) {
  77             print " (server -> client)\n";
  78         } else {
  79             print " (client -> server)\n";
  80         }
  81         #Get the record header
  82         if (length($packet) < TLS_RECORD_HEADER_LENGTH) {
  83             print "Partial data : ".length($packet)." bytes\n";
  84             $packet = "";
  85         } else {
  86             ($content_type, $version, $len) = unpack('CnnC*', $packet);
  87             $data = substr($packet, 5, $len);
  88
  89             print "  Content type: ".$record_type{$content_type}."\n";
  90             print "  Version: $tls_version{$version}\n";
  91             print "  Length: $len";
  92             if ($len == length($data)) {
  93                 print "\n";
  94                 $decrypt_len = $len_real = $len;
  95             } else {
  96                 print " (expected), ".length($data)." (actual)\n";
  97                 $decrypt_len = $len_real = length($data);
  98             }
  99
 100             my $record = TLSProxy::Record->new(
 101                 $flight,
 102                 $content_type,
 103                 $version,
 104                 $len,
 105                 0,
 106                 $len_real,
 107                 $decrypt_len,
 108                 substr($packet, TLS_RECORD_HEADER_LENGTH, $len_real),
 109                 substr($packet, TLS_RECORD_HEADER_LENGTH, $len_real)
 110             );
 111
 112             if (($server && $server_encrypting)
 113                      || (!$server && $client_encrypting)) {
 114                 if (!TLSProxy::Proxy->is_tls13() && $etm) {
 115                     $record->decryptETM();
 116                 } else {
 117                     $record->decrypt();
 118                 }
 119                 $record->encrypted(1);
 120             }
 121
 122             if (TLSProxy::Proxy->is_tls13()) {
 123                 print "  Inner content type: "
 124                       .$record_type{$record->content_type()}."\n";
 125             }
 126
 127             push @record_list, $record;
 128
 129             #Now figure out what messages are contained within this record
 130             my @messages = TLSProxy::Message->get_messages($server, $record);
 131             push @message_list, @messages;
 132
 133             $packet = substr($packet, TLS_RECORD_HEADER_LENGTH + $len_real);
 134             $recnum++;
 135         }
 136     }
 137
 138     return (\@record_list, \@message_list);
 139 }
 140
 141 sub clear
 142 {
 143     $server_encrypting = 0;
 144     $client_encrypting = 0;
 145 }
 146
 147 #Class level accessors
 148 sub server_encrypting
 149 {
 150     my $class = shift;
 151     if (@_) {
 152       $server_encrypting = shift;
 153     }
 154     return $server_encrypting;
 155 }
 156 sub client_encrypting
 157 {
 158     my $class = shift;
 159     if (@_) {
 160       $client_encrypting= shift;
 161     }
 162     return $client_encrypting;
 163 }
 164 #Enable/Disable Encrypt-then-MAC
 165 sub etm
 166 {
 167     my $class = shift;
 168     if (@_) {
 169       $etm = shift;
 170     }
 171     return $etm;
 172 }
 173
 174 sub new
 175 {
 176     my $class = shift;
 177     my ($flight,
 178         $content_type,
 179         $version,
 180         $len,
 181         $sslv2,
 182         $len_real,
 183         $decrypt_len,
 184         $data,
 185         $decrypt_data) = @_;
 186
 187     my $self = {
 188         flight => $flight,
 189         content_type => $content_type,
 190         version => $version,
 191         len => $len,
 192         sslv2 => $sslv2,
 193         len_real => $len_real,
 194         decrypt_len => $decrypt_len,
 195         data => $data,
 196         decrypt_data => $decrypt_data,
 197         orig_decrypt_data => $decrypt_data,
 198         encrypted => 0,
 199         outer_content_type => RT_APPLICATION_DATA
 200     };
 201
 202     return bless $self, $class;
 203 }
 204
 205 #Decrypt using encrypt-then-MAC
 206 sub decryptETM
 207 {
 208     my ($self) = shift;
 209
 210     my $data = $self->data;
 211
 212     if($self->version >= VERS_TLS_1_1()) {
 213         #TLS1.1+ has an explicit IV. Throw it away
 214         $data = substr($data, 16);
 215     }
 216
 217     #Throw away the MAC (assumes MAC is 20 bytes for now. FIXME)
 218     $data = substr($data, 0, length($data) - 20);
 219
 220     #Find out what the padding byte is
 221     my $padval = unpack("C", substr($data, length($data) - 1));
 222
 223     #Throw away the padding
 224     $data = substr($data, 0, length($data) - ($padval + 1));
 225
 226     $self->decrypt_data($data);
 227     $self->decrypt_len(length($data));
 228
 229     return $data;
 230 }
 231
 232 #Standard decrypt
 233 sub decrypt()
 234 {
 235     my ($self) = shift;
 236     my $mactaglen = 20;
 237     my $data = $self->data;
 238
 239     #Throw away any IVs
 240     if (TLSProxy::Proxy->is_tls13()) {
 241         #A TLS1.3 client, when processing the server's initial flight, could
 242         #respond with either an encrypted or an unencrypted alert.
 243         if ($self->content_type() == RT_ALERT) {
 244             #TODO(TLS1.3): Eventually it is sufficient just to check the record
 245             #content type. If an alert is encrypted it will have a record
 246             #content type of application data. However we haven't done the
 247             #record layer changes yet, so it's a bit more complicated. For now
 248             #we will additionally check if the data length is 2 (1 byte for
 249             #alert level, 1 byte for alert description). If it is, then this is
 250             #an unencrypted alert, so don't try to decrypt
 251             return $data if (length($data) == 2);
 252         }
 253         $mactaglen = 16;
 254     } elsif ($self->version >= VERS_TLS_1_1()) {
 255         #16 bytes for a standard IV
 256         $data = substr($data, 16);
 257
 258         #Find out what the padding byte is
 259         my $padval = unpack("C", substr($data, length($data) - 1));
 260
 261         #Throw away the padding
 262         $data = substr($data, 0, length($data) - ($padval + 1));
 263     }
 264
 265     #Throw away the MAC or TAG
 266     $data = substr($data, 0, length($data) - $mactaglen);
 267
 268     if (TLSProxy::Proxy->is_tls13()) {
 269         #Get the content type
 270         my $content_type = unpack("C", substr($data, length($data) - 1));
 271         $self->content_type($content_type);
 272         $data = substr($data, 0, length($data) - 1);
 273     }
 274
 275     $self->decrypt_data($data);
 276     $self->decrypt_len(length($data));
 277
 278     return $data;
 279 }
 280
 281 #Reconstruct the on-the-wire record representation
 282 sub reconstruct_record
 283 {
 284     my $self = shift;
 285     my $server = shift;
 286     my $data;
 287     my $tls13_enc = 0;
 288
 289     if ($self->sslv2) {
 290         $data = pack('n', $self->len | 0x8000);
 291     } else {
 292         if (TLSProxy::Proxy->is_tls13() && $self->encrypted) {
 293             $data = pack('Cnn', $self->outer_content_type, $self->version,
 294                          $self->len + 1);
 295             $tls13_enc = 1;
 296         } else {
 297             $data = pack('Cnn', $self->content_type, $self->version,
 298                          $self->len);
 299         }
 300
 301     }
 302     $data .= $self->data;
 303
 304     if ($tls13_enc) {
 305         $data .= pack('C', $self->content_type);
 306     }
 307
 308     return $data;
 309 }
 310
 311 #Read only accessors
 312 sub flight
 313 {
 314     my $self = shift;
 315     return $self->{flight};
 316 }
 317 sub sslv2
 318 {
 319     my $self = shift;
 320     return $self->{sslv2};
 321 }
 322 sub len_real
 323 {
 324     my $self = shift;
 325     return $self->{len_real};
 326 }
 327 sub orig_decrypt_data
 328 {
 329     my $self = shift;
 330     return $self->{orig_decrypt_data};
 331 }
 332
 333 #Read/write accessors
 334 sub decrypt_len
 335 {
 336     my $self = shift;
 337     if (@_) {
 338       $self->{decrypt_len} = shift;
 339     }
 340     return $self->{decrypt_len};
 341 }
 342 sub data
 343 {
 344     my $self = shift;
 345     if (@_) {
 346       $self->{data} = shift;
 347     }
 348     return $self->{data};
 349 }
 350 sub decrypt_data
 351 {
 352     my $self = shift;
 353     if (@_) {
 354       $self->{decrypt_data} = shift;
 355     }
 356     return $self->{decrypt_data};
 357 }
 358 sub len
 359 {
 360     my $self = shift;
 361     if (@_) {
 362       $self->{len} = shift;
 363     }
 364     return $self->{len};
 365 }
 366 sub version
 367 {
 368     my $self = shift;
 369     if (@_) {
 370       $self->{version} = shift;
 371     }
 372     return $self->{version};
 373 }
 374 sub content_type
 375 {
 376     my $self = shift;
 377     if (@_) {
 378       $self->{content_type} = shift;
 379     }
 380     return $self->{content_type};
 381 }
 382 sub encrypted
 383 {
 384     my $self = shift;
 385     if (@_) {
 386       $self->{encrypted} = shift;
 387     }
 388     return $self->{encrypted};
 389 }
 390 sub outer_content_type
 391 {
 392     my $self = shift;
 393     if (@_) {
 394       $self->{outer_content_type} = shift;
 395     }
 396     return $self->{outer_content_type};
 397 }
 398 1;