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![Tobin C. Harding](/assets/img/avatar_default.png)
Signal masks are false positives, we already check for SigBlk and SigCgt but we missed SigIgn. Add SigIgn to false positive check. Signed-off-by: Tobin C. Harding <me@tobin.cc>
501 lines
9.6 KiB
Perl
Executable file
501 lines
9.6 KiB
Perl
Executable file
#!/usr/bin/env perl
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#
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# (c) 2017 Tobin C. Harding <me@tobin.cc>
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# Licensed under the terms of the GNU GPL License version 2
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#
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# leaking_addresses.pl: Scan 64 bit kernel for potential leaking addresses.
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# - Scans dmesg output.
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# - Walks directory tree and parses each file (for each directory in @DIRS).
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#
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# Use --debug to output path before parsing, this is useful to find files that
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# cause the script to choke.
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#
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# You may like to set kptr_restrict=2 before running script
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# (see Documentation/sysctl/kernel.txt).
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use warnings;
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use strict;
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use POSIX;
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use File::Basename;
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use File::Spec;
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use Cwd 'abs_path';
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use Term::ANSIColor qw(:constants);
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use Getopt::Long qw(:config no_auto_abbrev);
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use Config;
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my $P = $0;
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my $V = '0.01';
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# Directories to scan.
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my @DIRS = ('/proc', '/sys');
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# Timer for parsing each file, in seconds.
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my $TIMEOUT = 10;
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# Script can only grep for kernel addresses on the following architectures. If
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# your architecture is not listed here and has a grep'able kernel address please
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# consider submitting a patch.
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my @SUPPORTED_ARCHITECTURES = ('x86_64', 'ppc64');
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# Command line options.
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my $help = 0;
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my $debug = 0;
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my $raw = 0;
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my $output_raw = ""; # Write raw results to file.
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my $input_raw = ""; # Read raw results from file instead of scanning.
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my $suppress_dmesg = 0; # Don't show dmesg in output.
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my $squash_by_path = 0; # Summary report grouped by absolute path.
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my $squash_by_filename = 0; # Summary report grouped by filename.
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# Do not parse these files (absolute path).
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my @skip_parse_files_abs = ('/proc/kmsg',
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'/proc/kcore',
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'/proc/fs/ext4/sdb1/mb_groups',
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'/proc/1/fd/3',
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'/sys/firmware/devicetree',
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'/proc/device-tree',
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'/sys/kernel/debug/tracing/trace_pipe',
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'/sys/kernel/security/apparmor/revision');
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# Do not parse these files under any subdirectory.
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my @skip_parse_files_any = ('0',
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'1',
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'2',
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'pagemap',
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'events',
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'access',
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'registers',
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'snapshot_raw',
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'trace_pipe_raw',
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'ptmx',
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'trace_pipe');
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# Do not walk these directories (absolute path).
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my @skip_walk_dirs_abs = ();
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# Do not walk these directories under any subdirectory.
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my @skip_walk_dirs_any = ('self',
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'thread-self',
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'cwd',
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'fd',
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'usbmon',
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'stderr',
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'stdin',
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'stdout');
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sub help
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{
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my ($exitcode) = @_;
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print << "EOM";
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Usage: $P [OPTIONS]
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Version: $V
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Options:
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-o, --output-raw=<file> Save results for future processing.
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-i, --input-raw=<file> Read results from file instead of scanning.
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--raw Show raw results (default).
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--suppress-dmesg Do not show dmesg results.
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--squash-by-path Show one result per unique path.
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--squash-by-filename Show one result per unique filename.
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-d, --debug Display debugging output.
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-h, --help, --version Display this help and exit.
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Examples:
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# Scan kernel and dump raw results.
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$0
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# Scan kernel and save results to file.
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$0 --output-raw scan.out
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# View summary report.
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$0 --input-raw scan.out --squash-by-filename
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Scans the running (64 bit) kernel for potential leaking addresses.
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EOM
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exit($exitcode);
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}
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GetOptions(
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'd|debug' => \$debug,
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'h|help' => \$help,
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'version' => \$help,
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'o|output-raw=s' => \$output_raw,
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'i|input-raw=s' => \$input_raw,
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'suppress-dmesg' => \$suppress_dmesg,
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'squash-by-path' => \$squash_by_path,
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'squash-by-filename' => \$squash_by_filename,
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'raw' => \$raw,
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) or help(1);
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help(0) if ($help);
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if ($input_raw) {
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format_output($input_raw);
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exit(0);
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}
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if (!$input_raw and ($squash_by_path or $squash_by_filename)) {
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printf "\nSummary reporting only available with --input-raw=<file>\n";
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printf "(First run scan with --output-raw=<file>.)\n";
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exit(128);
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}
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if (!is_supported_architecture()) {
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printf "\nScript does not support your architecture, sorry.\n";
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printf "\nCurrently we support: \n\n";
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foreach(@SUPPORTED_ARCHITECTURES) {
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printf "\t%s\n", $_;
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}
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my $archname = $Config{archname};
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printf "\n\$ perl -MConfig -e \'print \"\$Config{archname}\\n\"\'\n";
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printf "%s\n", $archname;
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exit(129);
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}
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if ($output_raw) {
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open my $fh, '>', $output_raw or die "$0: $output_raw: $!\n";
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select $fh;
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}
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parse_dmesg();
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walk(@DIRS);
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exit 0;
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sub dprint
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{
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printf(STDERR @_) if $debug;
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}
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sub is_supported_architecture
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{
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return (is_x86_64() or is_ppc64());
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}
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sub is_x86_64
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{
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my $archname = $Config{archname};
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if ($archname =~ m/x86_64/) {
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return 1;
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}
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return 0;
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}
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sub is_ppc64
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{
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my $archname = $Config{archname};
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if ($archname =~ m/powerpc/ and $archname =~ m/64/) {
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return 1;
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}
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return 0;
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}
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sub is_false_positive
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{
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my ($match) = @_;
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if ($match =~ '\b(0x)?(f|F){16}\b' or
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$match =~ '\b(0x)?0{16}\b') {
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return 1;
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}
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if (is_x86_64) {
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# vsyscall memory region, we should probably check against a range here.
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if ($match =~ '\bf{10}600000\b' or
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$match =~ '\bf{10}601000\b') {
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return 1;
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}
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}
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return 0;
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}
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# True if argument potentially contains a kernel address.
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sub may_leak_address
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{
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my ($line) = @_;
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my $address_re;
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# Signal masks.
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if ($line =~ '^SigBlk:' or
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$line =~ '^SigIgn:' or
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$line =~ '^SigCgt:') {
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return 0;
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}
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if ($line =~ '\bKEY=[[:xdigit:]]{14} [[:xdigit:]]{16} [[:xdigit:]]{16}\b' or
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$line =~ '\b[[:xdigit:]]{14} [[:xdigit:]]{16} [[:xdigit:]]{16}\b') {
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return 0;
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}
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# One of these is guaranteed to be true.
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if (is_x86_64()) {
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$address_re = '\b(0x)?ffff[[:xdigit:]]{12}\b';
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} elsif (is_ppc64()) {
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$address_re = '\b(0x)?[89abcdef]00[[:xdigit:]]{13}\b';
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}
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while (/($address_re)/g) {
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if (!is_false_positive($1)) {
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return 1;
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}
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}
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return 0;
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}
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sub parse_dmesg
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{
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open my $cmd, '-|', 'dmesg';
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while (<$cmd>) {
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if (may_leak_address($_)) {
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print 'dmesg: ' . $_;
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}
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}
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close $cmd;
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}
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# True if we should skip this path.
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sub skip
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{
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my ($path, $paths_abs, $paths_any) = @_;
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foreach (@$paths_abs) {
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return 1 if (/^$path$/);
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}
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my($filename, $dirs, $suffix) = fileparse($path);
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foreach (@$paths_any) {
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return 1 if (/^$filename$/);
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}
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return 0;
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}
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sub skip_parse
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{
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my ($path) = @_;
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return skip($path, \@skip_parse_files_abs, \@skip_parse_files_any);
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}
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sub timed_parse_file
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{
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my ($file) = @_;
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eval {
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local $SIG{ALRM} = sub { die "alarm\n" }; # NB: \n required.
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alarm $TIMEOUT;
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parse_file($file);
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alarm 0;
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};
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if ($@) {
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die unless $@ eq "alarm\n"; # Propagate unexpected errors.
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printf STDERR "timed out parsing: %s\n", $file;
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}
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}
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sub parse_file
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{
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my ($file) = @_;
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if (! -R $file) {
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return;
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}
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if (skip_parse($file)) {
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dprint "skipping file: $file\n";
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return;
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}
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dprint "parsing: $file\n";
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open my $fh, "<", $file or return;
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while ( <$fh> ) {
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if (may_leak_address($_)) {
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print $file . ': ' . $_;
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}
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}
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close $fh;
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}
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# True if we should skip walking this directory.
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sub skip_walk
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{
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my ($path) = @_;
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return skip($path, \@skip_walk_dirs_abs, \@skip_walk_dirs_any)
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}
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# Recursively walk directory tree.
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sub walk
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{
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my @dirs = @_;
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while (my $pwd = shift @dirs) {
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next if (skip_walk($pwd));
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next if (!opendir(DIR, $pwd));
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my @files = readdir(DIR);
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closedir(DIR);
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foreach my $file (@files) {
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next if ($file eq '.' or $file eq '..');
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my $path = "$pwd/$file";
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next if (-l $path);
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if (-d $path) {
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push @dirs, $path;
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} else {
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timed_parse_file($path);
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}
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}
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}
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}
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sub format_output
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{
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my ($file) = @_;
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# Default is to show raw results.
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if ($raw or (!$squash_by_path and !$squash_by_filename)) {
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dump_raw_output($file);
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return;
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}
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my ($total, $dmesg, $paths, $files) = parse_raw_file($file);
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printf "\nTotal number of results from scan (incl dmesg): %d\n", $total;
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if (!$suppress_dmesg) {
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print_dmesg($dmesg);
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}
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if ($squash_by_filename) {
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squash_by($files, 'filename');
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}
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if ($squash_by_path) {
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squash_by($paths, 'path');
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}
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}
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sub dump_raw_output
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{
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my ($file) = @_;
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open (my $fh, '<', $file) or die "$0: $file: $!\n";
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while (<$fh>) {
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if ($suppress_dmesg) {
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if ("dmesg:" eq substr($_, 0, 6)) {
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next;
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}
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}
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print $_;
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}
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close $fh;
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}
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sub parse_raw_file
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{
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my ($file) = @_;
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my $total = 0; # Total number of lines parsed.
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my @dmesg; # dmesg output.
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my %files; # Unique filenames containing leaks.
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my %paths; # Unique paths containing leaks.
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open (my $fh, '<', $file) or die "$0: $file: $!\n";
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while (my $line = <$fh>) {
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$total++;
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if ("dmesg:" eq substr($line, 0, 6)) {
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push @dmesg, $line;
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next;
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}
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cache_path(\%paths, $line);
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cache_filename(\%files, $line);
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}
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return $total, \@dmesg, \%paths, \%files;
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}
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sub print_dmesg
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{
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my ($dmesg) = @_;
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print "\ndmesg output:\n";
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if (@$dmesg == 0) {
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print "<no results>\n";
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return;
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}
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foreach(@$dmesg) {
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my $index = index($_, ': ');
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$index += 2; # skid ': '
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print substr($_, $index);
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}
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}
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sub squash_by
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{
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my ($ref, $desc) = @_;
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print "\nResults squashed by $desc (excl dmesg). ";
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print "Displaying [<number of results> <$desc>], <example result>\n";
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if (keys %$ref == 0) {
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print "<no results>\n";
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return;
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}
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foreach(keys %$ref) {
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my $lines = $ref->{$_};
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my $length = @$lines;
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printf "[%d %s] %s", $length, $_, @$lines[0];
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}
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}
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sub cache_path
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{
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my ($paths, $line) = @_;
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my $index = index($line, ': ');
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my $path = substr($line, 0, $index);
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$index += 2; # skip ': '
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add_to_cache($paths, $path, substr($line, $index));
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}
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sub cache_filename
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{
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my ($files, $line) = @_;
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my $index = index($line, ': ');
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my $path = substr($line, 0, $index);
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my $filename = basename($path);
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$index += 2; # skip ': '
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add_to_cache($files, $filename, substr($line, $index));
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}
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sub add_to_cache
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{
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my ($cache, $key, $value) = @_;
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if (!$cache->{$key}) {
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$cache->{$key} = ();
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}
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push @{$cache->{$key}}, $value;
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}
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