TOMOYO Linux Cross Reference
Linux/scripts/leaking_addresses.pl

   #!/usr/bin/env perl
   # SPDX-License-Identifier: GPL-2.0-only
   #
   # (c) 2017 Tobin C. Harding <me@tobin.cc>
   #
   # leaking_addresses.pl: Scan the kernel for potential leaking addresses.
   #  - Scans dmesg output.
   #  - Walks directory tree and parses each file (for each directory in @DIRS).
   #
  # Use --debug to output path before parsing, this is useful to find files that
  # cause the script to choke.
  
  #
  # When the system is idle it is likely that most files under /proc/PID will be
  # identical for various processes.  Scanning _all_ the PIDs under /proc is
  # unnecessary and implies that we are thoroughly scanning /proc.  This is _not_
  # the case because there may be ways userspace can trigger creation of /proc
  # files that leak addresses but were not present during a scan.  For these two
  # reasons we exclude all PID directories under /proc except '1/'
  
  use warnings;
  use strict;
  use POSIX;
  use File::Basename;
  use File::Spec;
  use File::Temp qw/tempfile/;
  use Cwd 'abs_path';
  use Term::ANSIColor qw(:constants);
  use Getopt::Long qw(:config no_auto_abbrev);
  use Config;
  use bigint qw/hex/;
  use feature 'state';
  
  my $P = $0;
  
  # Directories to scan.
  my @DIRS = ('/proc', '/sys');
  
  # Timer for parsing each file, in seconds.
  my $TIMEOUT = 10;
  
  # Kernel addresses vary by architecture.  We can only auto-detect the following
  # architectures (using `uname -m`).  (flag --32-bit overrides auto-detection.)
  my @SUPPORTED_ARCHITECTURES = ('x86_64', 'ppc64', 'x86');
  
  # Command line options.
  my $help = 0;
  my $debug = 0;
  my $raw = 0;
  my $output_raw = "";    # Write raw results to file.
  my $input_raw = "";     # Read raw results from file instead of scanning.
  my $suppress_dmesg = 0;         # Don't show dmesg in output.
  my $squash_by_path = 0;         # Summary report grouped by absolute path.
  my $squash_by_filename = 0;     # Summary report grouped by filename.
  my $kallsyms_file = "";         # Kernel symbols file.
  my $kernel_config_file = "";    # Kernel configuration file.
  my $opt_32bit = 0;              # Scan 32-bit kernel.
  my $page_offset_32bit = 0;      # Page offset for 32-bit kernel.
  
  my @kallsyms = ();
  
  # Skip these absolute paths.
  my @skip_abs = (
          '/proc/kmsg',
          '/proc/device-tree',
          '/proc/1/syscall',
          '/sys/firmware/devicetree',
          '/sys/kernel/tracing/trace_pipe',
          '/sys/kernel/debug/tracing/trace_pipe',
          '/sys/kernel/security/apparmor/revision');
  
  # Skip these under any subdirectory.
  my @skip_any = (
          'pagemap',
          'events',
          'access',
          'registers',
          'snapshot_raw',
          'trace_pipe_raw',
          'ptmx',
          'trace_pipe',
          'fd',
          'usbmon');
  
  sub help
  {
          my ($exitcode) = @_;
  
          print << "EOM";
  
  Usage: $P [OPTIONS]
  
  Options:
  
          -o, --output-raw=<file>         Save results for future processing.
          -i, --input-raw=<file>          Read results from file instead of scanning.
                --raw                     Show raw results (default).
                --suppress-dmesg          Do not show dmesg results.
                --squash-by-path          Show one result per unique path.
               --squash-by-filename      Show one result per unique filename.
         --kernel-config-file=<file>     Kernel configuration file (e.g /boot/config)
         --kallsyms=<file>               Read kernel symbol addresses from file (for
                                                 scanning binary files).
         --32-bit                        Scan 32-bit kernel.
         --page-offset-32-bit=o          Page offset (for 32-bit kernel 0xABCD1234).
         -d, --debug                     Display debugging output.
         -h, --help                      Display this help and exit.
 
 Scans the running kernel for potential leaking addresses.
 
 EOM
         exit($exitcode);
 }
 
 GetOptions(
         'd|debug'               => \$debug,
         'h|help'                => \$help,
         'o|output-raw=s'        => \$output_raw,
         'i|input-raw=s'         => \$input_raw,
         'suppress-dmesg'        => \$suppress_dmesg,
         'squash-by-path'        => \$squash_by_path,
         'squash-by-filename'    => \$squash_by_filename,
         'raw'                   => \$raw,
         'kallsyms=s'            => \$kallsyms_file,
         'kernel-config-file=s'  => \$kernel_config_file,
         '32-bit'                => \$opt_32bit,
         'page-offset-32-bit=o'  => \$page_offset_32bit,
 ) or help(1);
 
 help(0) if ($help);
 
 if ($input_raw) {
         format_output($input_raw);
         exit(0);
 }
 
 if (!$input_raw and ($squash_by_path or $squash_by_filename)) {
         printf "\nSummary reporting only available with --input-raw=<file>\n";
         printf "(First run scan with --output-raw=<file>.)\n";
         exit(128);
 }
 
 if (!(is_supported_architecture() or $opt_32bit or $page_offset_32bit)) {
         printf "\nScript does not support your architecture, sorry.\n";
         printf "\nCurrently we support: \n\n";
         foreach(@SUPPORTED_ARCHITECTURES) {
                 printf "\t%s\n", $_;
         }
         printf("\n");
 
         printf("If you are running a 32-bit architecture you may use:\n");
         printf("\n\t--32-bit or --page-offset-32-bit=<page offset>\n\n");
 
         my $archname = `uname -m`;
         printf("Machine hardware name (`uname -m`): %s\n", $archname);
 
         exit(129);
 }
 
 if ($output_raw) {
         open my $fh, '>', $output_raw or die "$0: $output_raw: $!\n";
         select $fh;
 }
 
 if ($kallsyms_file) {
         open my $fh, '<', $kallsyms_file or die "$0: $kallsyms_file: $!\n";
         while (<$fh>) {
                 chomp;
                 my @entry = split / /, $_;
                 my $addr_text = $entry[0];
                 if ($addr_text !~ /^0/) {
                         # TODO: Why is hex() so impossibly slow?
                         my $addr = hex($addr_text);
                         my $symbol = $entry[2];
                         # Only keep kernel text addresses.
                         my $long = pack("J", $addr);
                         my $entry = [$long, $symbol];
                         push @kallsyms, $entry;
                 }
         }
         close $fh;
 }
 
 parse_dmesg();
 walk(@DIRS);
 
 exit 0;
 
 sub dprint
 {
         printf(STDERR @_) if $debug;
 }
 
 sub is_supported_architecture
 {
         return (is_x86_64() or is_ppc64() or is_ix86_32());
 }
 
 sub is_32bit
 {
         # Allow --32-bit or --page-offset-32-bit to override
         if ($opt_32bit or $page_offset_32bit) {
                 return 1;
         }
 
         return is_ix86_32();
 }
 
 sub is_ix86_32
 {
        state $arch = `uname -m`;
 
        chomp $arch;
        if ($arch =~ m/i[3456]86/) {
                return 1;
        }
        return 0;
 }
 
 sub is_arch
 {
        my ($desc) = @_;
        my $arch = `uname -m`;
 
        chomp $arch;
        if ($arch eq $desc) {
                return 1;
        }
        return 0;
 }
 
 sub is_x86_64
 {
         state $is = is_arch('x86_64');
         return $is;
 }
 
 sub is_ppc64
 {
         state $is = is_arch('ppc64');
         return $is;
 }
 
 # Gets config option value from kernel config file.
 # Returns "" on error or if config option not found.
 sub get_kernel_config_option
 {
         my ($option) = @_;
         my $value = "";
         my $tmp_fh;
         my $tmp_file = "";
         my @config_files;
 
         # Allow --kernel-config-file to override.
         if ($kernel_config_file ne "") {
                 @config_files = ($kernel_config_file);
         } elsif (-R "/proc/config.gz") {
                 ($tmp_fh, $tmp_file) = tempfile("config.gz-XXXXXX",
                                                 UNLINK => 1);
 
                 if (system("gunzip < /proc/config.gz > $tmp_file")) {
                         dprint("system(gunzip < /proc/config.gz) failed\n");
                         return "";
                 } else {
                         @config_files = ($tmp_file);
                 }
         } else {
                 my $file = '/boot/config-' . `uname -r`;
                 chomp $file;
                 @config_files = ($file, '/boot/config');
         }
 
         foreach my $file (@config_files) {
                 dprint("parsing config file: $file\n");
                 $value = option_from_file($option, $file);
                 if ($value ne "") {
                         last;
                 }
         }
 
         return $value;
 }
 
 # Parses $file and returns kernel configuration option value.
 sub option_from_file
 {
         my ($option, $file) = @_;
         my $str = "";
         my $val = "";
 
         open(my $fh, "<", $file) or return "";
         while (my $line = <$fh> ) {
                 if ($line =~ /^$option/) {
                         ($str, $val) = split /=/, $line;
                         chomp $val;
                         last;
                 }
         }
 
         close $fh;
         return $val;
 }
 
 sub is_false_positive
 {
         my ($match) = @_;
 
         if (is_32bit()) {
                 return is_false_positive_32bit($match);
         }
 
         # Ignore 64 bit false positives:
         # 0xfffffffffffffff[0-f]
         # 0x0000000000000000
         if ($match =~ '\b(0x)?(f|F){15}[0-9a-f]\b' or
             $match =~ '\b(0x)?0{16}\b') {
                 return 1;
         }
 
         if (is_x86_64() and is_in_vsyscall_memory_region($match)) {
                 return 1;
         }
 
         return 0;
 }
 
 sub is_false_positive_32bit
 {
        my ($match) = @_;
        state $page_offset = get_page_offset();
 
        if ($match =~ '\b(0x)?(f|F){7}[0-9a-f]\b') {
                return 1;
        }
 
        if (hex($match) < $page_offset) {
                return 1;
        }
 
        return 0;
 }
 
 # returns integer value
 sub get_page_offset
 {
        my $page_offset;
        my $default_offset = 0xc0000000;
 
        # Allow --page-offset-32bit to override.
        if ($page_offset_32bit != 0) {
                return $page_offset_32bit;
        }
 
        $page_offset = get_kernel_config_option('CONFIG_PAGE_OFFSET');
        if (!$page_offset) {
                return $default_offset;
        }
        return $page_offset;
 }
 
 sub is_in_vsyscall_memory_region
 {
         my ($match) = @_;
 
         my $hex = hex($match);
         my $region_min = hex("0xffffffffff600000");
         my $region_max = hex("0xffffffffff601000");
 
         return ($hex >= $region_min and $hex <= $region_max);
 }
 
 # True if argument potentially contains a kernel address.
 sub may_leak_address
 {
         my ($path, $line) = @_;
         my $address_re;
 
         # Ignore Signal masks.
         if ($line =~ '^SigBlk:' or
             $line =~ '^SigIgn:' or
             $line =~ '^SigCgt:') {
                 return 0;
         }
 
         # Ignore input device reporting.
         # /proc/bus/input/devices: B: KEY=402000000 3803078f800d001 feffffdfffefffff fffffffffffffffe
         # /sys/devices/platform/i8042/serio0/input/input1/uevent: KEY=402000000 3803078f800d001 feffffdfffefffff fffffffffffffffe
         # /sys/devices/platform/i8042/serio0/input/input1/capabilities/key: 402000000 3803078f800d001 feffffdfffefffff fffffffffffffffe
         if ($line =~ '\bKEY=[[:xdigit:]]{9,14} [[:xdigit:]]{16} [[:xdigit:]]{16}\b' or
             ($path =~ '\bkey$' and
              $line =~ '\b[[:xdigit:]]{9,14} [[:xdigit:]]{16} [[:xdigit:]]{16}\b')) {
                 return 0;
         }
 
         $address_re = get_address_re();
         while ($line =~ /($address_re)/g) {
                 if (!is_false_positive($1)) {
                         return 1;
                 }
         }
 
         return 0;
 }
 
 sub get_address_re
 {
         if (is_ppc64()) {
                 return '\b(0x)?[89abcdef]00[[:xdigit:]]{13}\b';
         } elsif (is_32bit()) {
                 return '\b(0x)?[[:xdigit:]]{8}\b';
         }
 
         return get_x86_64_re();
 }
 
 sub get_x86_64_re
 {
         # We handle page table levels but only if explicitly configured using
         # CONFIG_PGTABLE_LEVELS.  If config file parsing fails or config option
         # is not found we default to using address regular expression suitable
         # for 4 page table levels.
         state $ptl = get_kernel_config_option('CONFIG_PGTABLE_LEVELS');
 
         if ($ptl == 5) {
                 return '\b(0x)?ff[[:xdigit:]]{14}\b';
         }
         return '\b(0x)?ffff[[:xdigit:]]{12}\b';
 }
 
 sub parse_dmesg
 {
         open my $cmd, '-|', 'dmesg';
         while (<$cmd>) {
                 if (may_leak_address("dmesg", $_)) {
                         print 'dmesg: ' . $_;
                 }
         }
         close $cmd;
 }
 
 # True if we should skip this path.
 sub skip
 {
         my ($path) = @_;
 
         foreach (@skip_abs) {
                 return 1 if (/^$path$/);
         }
 
         my($filename, $dirs, $suffix) = fileparse($path);
         foreach (@skip_any) {
                 return 1 if (/^$filename$/);
         }
 
         return 0;
 }
 
 sub timed_parse_file
 {
         my ($file) = @_;
 
         eval {
                 local $SIG{ALRM} = sub { die "alarm\n" }; # NB: \n required.
                 alarm $TIMEOUT;
                 parse_file($file);
                 alarm 0;
         };
 
         if ($@) {
                 die unless $@ eq "alarm\n";     # Propagate unexpected errors.
                 printf STDERR "timed out parsing: %s\n", $file;
         }
 }
 
 sub parse_binary
 {
         my ($file) = @_;
 
         open my $fh, "<:raw", $file or return;
         local $/ = undef;
         my $bytes = <$fh>;
         close $fh;
 
         foreach my $entry (@kallsyms) {
                 my $addr = $entry->[0];
                 my $symbol = $entry->[1];
                 my $offset = index($bytes, $addr);
                 if ($offset != -1) {
                         printf("$file: $symbol @ $offset\n");
                 }
         }
 }
 
 sub parse_file
 {
         my ($file) = @_;
 
         if (! -R $file) {
                 return;
         }
 
         if (! -T $file) {
                 if ($file =~ m|^/sys/kernel/btf/| or
                     $file =~ m|^/sys/devices/pci| or
                     $file =~ m|^/sys/firmware/efi/efivars/| or
                     $file =~ m|^/proc/bus/pci/|) {
                         return;
                 }
                 if (scalar @kallsyms > 0) {
                         parse_binary($file);
                 }
                 return;
         }
 
         open my $fh, "<", $file or return;
         while ( <$fh> ) {
                 chomp;
                 if (may_leak_address($file, $_)) {
                         printf("$file: $_\n");
                 }
         }
         close $fh;
 }
 
 # Checks if the actual path name is leaking a kernel address.
 sub check_path_for_leaks
 {
         my ($path) = @_;
 
         if (may_leak_address($path, $path)) {
                 printf("Path name may contain address: $path\n");
         }
 }
 
 # Recursively walk directory tree.
 sub walk
 {
         my @dirs = @_;
 
         while (my $pwd = shift @dirs) {
                 next if (!opendir(DIR, $pwd));
                 my @files = readdir(DIR);
                 closedir(DIR);
 
                 foreach my $file (@files) {
                         next if ($file eq '.' or $file eq '..');
 
                         my $path = "$pwd/$file";
                         next if (-l $path);
 
                         # skip /proc/PID except /proc/1
                         next if (($path =~ /^\/proc\/[0-9]+$/) &&
                                  ($path !~ /^\/proc\/1$/));
 
                         next if (skip($path));
 
                         check_path_for_leaks($path);
 
                         if (-d $path) {
                                 push @dirs, $path;
                                 next;
                         }
 
                         dprint("parsing: $path\n");
                         timed_parse_file($path);
                 }
         }
 }
 
 sub format_output
 {
         my ($file) = @_;
 
         # Default is to show raw results.
         if ($raw or (!$squash_by_path and !$squash_by_filename)) {
                 dump_raw_output($file);
                 return;
         }
 
         my ($total, $dmesg, $paths, $files) = parse_raw_file($file);
 
         printf "\nTotal number of results from scan (incl dmesg): %d\n", $total;
 
         if (!$suppress_dmesg) {
                 print_dmesg($dmesg);
         }
 
         if ($squash_by_filename) {
                 squash_by($files, 'filename');
         }
 
         if ($squash_by_path) {
                 squash_by($paths, 'path');
         }
 }
 
 sub dump_raw_output
 {
         my ($file) = @_;
 
         open (my $fh, '<', $file) or die "$0: $file: $!\n";
         while (<$fh>) {
                 if ($suppress_dmesg) {
                         if ("dmesg:" eq substr($_, 0, 6)) {
                                 next;
                         }
                 }
                 print $_;
         }
         close $fh;
 }
 
 sub parse_raw_file
 {
         my ($file) = @_;
 
         my $total = 0;          # Total number of lines parsed.
         my @dmesg;              # dmesg output.
         my %files;              # Unique filenames containing leaks.
         my %paths;              # Unique paths containing leaks.
 
         open (my $fh, '<', $file) or die "$0: $file: $!\n";
         while (my $line = <$fh>) {
                 $total++;
 
                 if ("dmesg:" eq substr($line, 0, 6)) {
                         push @dmesg, $line;
                         next;
                 }
 
                 cache_path(\%paths, $line);
                 cache_filename(\%files, $line);
         }
 
         return $total, \@dmesg, \%paths, \%files;
 }
 
 sub print_dmesg
 {
         my ($dmesg) = @_;
 
         print "\ndmesg output:\n";
 
         if (@$dmesg == 0) {
                 print "<no results>\n";
                 return;
         }
 
         foreach(@$dmesg) {
                 my $index = index($_, ': ');
                 $index += 2;    # skid ': '
                 print substr($_, $index);
         }
 }
 
 sub squash_by
 {
         my ($ref, $desc) = @_;
 
         print "\nResults squashed by $desc (excl dmesg). ";
         print "Displaying [<number of results> <$desc>], <example result>\n";
 
         if (keys %$ref == 0) {
                 print "<no results>\n";
                 return;
         }
 
         foreach(keys %$ref) {
                 my $lines = $ref->{$_};
                 my $length = @$lines;
                 printf "[%d %s] %s", $length, $_, @$lines[0];
         }
 }
 
 sub cache_path
 {
         my ($paths, $line) = @_;
 
         my $index = index($line, ': ');
         my $path = substr($line, 0, $index);
 
         $index += 2;            # skip ': '
         add_to_cache($paths, $path, substr($line, $index));
 }
 
 sub cache_filename
 {
         my ($files, $line) = @_;
 
         my $index = index($line, ': ');
         my $path = substr($line, 0, $index);
         my $filename = basename($path);
 
         $index += 2;            # skip ': '
         add_to_cache($files, $filename, substr($line, $index));
 }
 
 sub add_to_cache
 {
         my ($cache, $key, $value) = @_;
 
         if (!$cache->{$key}) {
                 $cache->{$key} = ();
         }
         push @{$cache->{$key}}, $value;
 }

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