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-rwxr-xr-xscripts/leaking_addresses.pl647
1 files changed, 647 insertions, 0 deletions
diff --git a/scripts/leaking_addresses.pl b/scripts/leaking_addresses.pl
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+#!/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 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 $kernel_config_file = ""; # Kernel configuration file.
+my $opt_32bit = 0; # Scan 32-bit kernel.
+my $page_offset_32bit = 0; # Page offset for 32-bit kernel.
+
+# Skip these absolute paths.
+my @skip_abs = (
+ '/proc/kmsg',
+ '/proc/device-tree',
+ '/proc/1/syscall',
+ '/sys/firmware/devicetree',
+ '/sys/kernel/debug/tracing/trace_pipe',
+ '/sys/kernel/security/apparmor/revision');
+
+# Skip these under any subdirectory.
+my @skip_any = (
+ 'pagemap',
+ 'events',
+ 'access',
+ 'registers',
+ 'snapshot_raw',
+ 'trace_pipe_raw',
+ 'ptmx',
+ 'trace_pipe',
+ 'fd',
+ 'usbmon');
+
+sub help
+{
+ my ($exitcode) = @_;
+
+ print << "EOM";
+
+Usage: $P [OPTIONS]
+
+Options:
+
+ -o, --output-raw=<file> Save results for future processing.
+ -i, --input-raw=<file> Read results from file instead of scanning.
+ --raw Show raw results (default).
+ --suppress-dmesg Do not show dmesg results.
+ --squash-by-path Show one result per unique path.
+ --squash-by-filename Show one result per unique filename.
+ --kernel-config-file=<file> Kernel configuration file (e.g /boot/config)
+ --32-bit Scan 32-bit kernel.
+ --page-offset-32-bit=o Page offset (for 32-bit kernel 0xABCD1234).
+ -d, --debug Display debugging output.
+ -h, --help Display this help and exit.
+
+Scans the running kernel for potential leaking addresses.
+
+EOM
+ exit($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,
+ '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;
+}
+
+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 $tmp_file = "";
+ my @config_files;
+
+ # Allow --kernel-config-file to override.
+ if ($kernel_config_file ne "") {
+ @config_files = ($kernel_config_file);
+ } elsif (-R "/proc/config.gz") {
+ my $tmp_file = "/tmp/tmpkconf";
+
+ 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;
+ }
+ }
+
+ if ($tmp_file ne "") {
+ system("rm -f $tmp_file");
+ }
+
+ 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($match);
+ }
+
+ # 64 bit false positives.
+
+ if ($match =~ '\b(0x)?(f|F){16}\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){8}\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 <= $region_max);
+}
+
+# True if argument potentially contains a kernel address.
+sub may_leak_address
+{
+ my ($line) = @_;
+ my $address_re;
+
+ # Signal masks.
+ if ($line =~ '^SigBlk:' or
+ $line =~ '^SigIgn:' or
+ $line =~ '^SigCgt:') {
+ return 0;
+ }
+
+ if ($line =~ '\bKEY=[[:xdigit:]]{14} [[:xdigit:]]{16} [[:xdigit:]]{16}\b' or
+ $line =~ '\b[[:xdigit:]]{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($_)) {
+ 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", $file;
+ }
+}
+
+sub parse_file
+{
+ my ($file) = @_;
+
+ if (! -R $file) {
+ return;
+ }
+
+ if (! -T $file) {
+ return;
+ }
+
+ open my $fh, "<", $file or return;
+ while ( <$fh> ) {
+ chomp;
+ if (may_leak_address($_)) {
+ printf("$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)) {
+ 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;
+}