linux/scripts/leaking_addresses.pl at master · linuxkit/linux · GitHub

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#!/usr/bin/env perl

# SPDX-License-Identifier: GPL-2.0-only

# 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> ) {

if (may_leak_address($_)) {

print $file . ': ' . $_;

}

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;

}

linux/scripts/leaking_addresses.pl at master · linuxkit/linux · GitHub

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