Viewing file:  leaking_addresses.pl (9.65 KB) -rwxr-xr-x
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#!/usr/bin/env perl
#
# (c) 2017 Tobin C. Harding <me@tobin.cc>
# Licensed under the terms of the GNU GPL License version 2
#
# leaking_addresses.pl: Scan 64 bit 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.
#
# You may like to set kptr_restrict=2 before running script
# (see Documentation/sysctl/kernel.txt).
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;
my $P = $0;
my $V = '0.01';
# Directories to scan.
my @DIRS = ('/proc', '/sys');
# Timer for parsing each file, in seconds.
my $TIMEOUT = 10;
# Script can only grep for kernel addresses on the following architectures. If
# your architecture is not listed here and has a grep'able kernel address please
# consider submitting a patch.
my @SUPPORTED_ARCHITECTURES = ('x86_64', 'ppc64');
# 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 $squash_by_filename = 0; # Summary report grouped by filename.
# Do not parse these files (absolute path).
my @skip_parse_files_abs = ('/proc/kmsg',
'/proc/kcore',
'/proc/fs/ext4/sdb1/mb_groups',
'/proc/1/fd/3',
'/sys/firmware/devicetree',
'/proc/device-tree',
'/sys/kernel/debug/tracing/trace_pipe',
'/sys/kernel/security/apparmor/revision');
# Do not parse these files under any subdirectory.
my @skip_parse_files_any = ('0',
'1',
'2',
'pagemap',
'events',
'access',
'registers',
'snapshot_raw',
'trace_pipe_raw',
'ptmx',
'trace_pipe');
# Do not walk these directories (absolute path).
my @skip_walk_dirs_abs = ();
# Do not walk these directories under any subdirectory.
my @skip_walk_dirs_any = ('self',
'thread-self',
'cwd',
'fd',
'usbmon',
'stderr',
'stdin',
'stdout');
sub help
{
my ($exitcode) = @_;
print << "EOM";
Usage: $P [OPTIONS]
Version: $V
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.
-d, --debug Display debugging output.
-h, --help, --version Display this help and exit.
Examples:
# Scan kernel and dump raw results.
$0
# Scan kernel and save results to file.
$0 --output-raw scan.out
# View summary report.
$0 --input-raw scan.out --squash-by-filename
Scans the running (64 bit) kernel for potential leaking addresses.
EOM
exit($exitcode);
}
GetOptions(
'd|debug' => \$debug,
'h|help' => \$help,
'version' => \$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,
) 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()) {
printf "\nScript does not support your architecture, sorry.\n";
printf "\nCurrently we support: \n\n";
foreach(@SUPPORTED_ARCHITECTURES) {
printf "\t%s\n", $_;
}
my $archname = $Config{archname};
printf "\n\$ perl -MConfig -e \'print \"\$Config{archname}\\n\"\'\n";
printf "%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());
}
sub is_x86_64
{
my $archname = $Config{archname};
if ($archname =~ m/x86_64/) {
return 1;
}
return 0;
}
sub is_ppc64
{
my $archname = $Config{archname};
if ($archname =~ m/powerpc/ and $archname =~ m/64/) {
return 1;
}
return 0;
}
sub is_false_positive
{
my ($match) = @_;
if ($match =~ '\b(0x)?(f|F){16}\b' or
$match =~ '\b(0x)?0{16}\b') {
return 1;
}
if (is_x86_64) {
# vsyscall memory region, we should probably check against a range here.
if ($match =~ '\bf{10}600000\b' or
$match =~ '\bf{10}601000\b') {
return 1;
}
}
return 0;
}
# True if argument potentially contains a kernel address.
sub may_leak_address
{
my ($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;
}
# One of these is guaranteed to be true.
if (is_x86_64()) {
$address_re = '\b(0x)?ffff[[:xdigit:]]{12}\b';
} elsif (is_ppc64()) {
$address_re = '\b(0x)?[89abcdef]00[[:xdigit:]]{13}\b';
}
while (/($address_re)/g) {
if (!is_false_positive($1)) {
return 1;
}
}
return 0;
}
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, $paths_abs, $paths_any) = @_;
foreach (@$paths_abs) {
return 1 if (/^$path$/);
}
my($filename, $dirs, $suffix) = fileparse($path);
foreach (@$paths_any) {
return 1 if (/^$filename$/);
}
return 0;
}
sub skip_parse
{
my ($path) = @_;
return skip($path, \@skip_parse_files_abs, \@skip_parse_files_any);
}
sub timed_parse_file
{
my ($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 $file) {
return;
}
if (skip_parse($file)) {
dprint "skipping file: $file\n";
return;
}
dprint "parsing: $file\n";
open my $fh, "<", $file or return;
while ( <$fh> ) {
chomp;
if (may_leak_address($_)) {
printf("$file: $_\n");
}
}
close $fh;
}
# True if we should skip walking this directory.
sub skip_walk
{
my ($path) = @_;
return skip($path, \@skip_walk_dirs_abs, \@skip_walk_dirs_any)
}
# Recursively walk directory tree.
sub walk
{
my @dirs = @_;
while (my $pwd = shift @dirs) {
next if (skip_walk($pwd));
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);
if (-d $path) {
push @dirs, $path;
} else {
timed_parse_file($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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