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Diffstat (limited to 'scripts/leaking_addresses.pl')
| -rwxr-xr-x | scripts/leaking_addresses.pl | 648 |
1 files changed, 648 insertions, 0 deletions
diff --git a/scripts/leaking_addresses.pl b/scripts/leaking_addresses.pl new file mode 100755 index 000000000..6e4b0f7ae --- /dev/null +++ b/scripts/leaking_addresses.pl @@ -0,0 +1,648 @@ +#!/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 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: $P [OPTIONS] + +Options: + + -o, --output-raw=<file> Save results for future processing. + -i, --input-raw=<file> Read results from file instead of scanning. + --raw Show raw results (default). + --suppress-dmesg Do not show dmesg results. + --squash-by-path Show one result per unique path. + --squash-by-filename Show one result per unique filename. + --kernel-config-file=<file> Kernel configuration file (e.g /boot/config) + --32-bit Scan 32-bit kernel. + --page-offset-32-bit=o Page offset (for 32-bit kernel 0xABCD1234). + -d, --debug Display debugging output. + -h, --help, --version Display this help and exit. + +Scans the running kernel for potential leaking addresses. + +EOM + exit($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, + '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 "$0: system(gunzip < /proc/config.gz) failed\n"; + return ""; + } else { + @config_files = ($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: %s\n", $file); + $value = option_from_file($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; +} |