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305 lines
6.6 KiB
305 lines
6.6 KiB
#!/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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# You can configure the behaviour of the script;
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#
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# - By adding paths, for directories you do not want to walk;
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# absolute paths: @skip_walk_dirs_abs
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# directory names: @skip_walk_dirs_any
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#
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# - By adding paths, for files you do not want to parse;
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# absolute paths: @skip_parse_files_abs
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# file names: @skip_parse_files_any
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#
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# The use of @skip_xxx_xxx_any causes files to be skipped where ever they occur.
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# For example adding 'fd' to @skip_walk_dirs_any causes the fd/ directory to be
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# skipped for all PID sub-directories of /proc
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#
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# The same thing can be achieved by passing command line options to --dont-walk
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# and --dont-parse. If absolute paths are supplied to these options they are
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# appended to the @skip_xxx_xxx_abs arrays. If file names are supplied to these
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# options, they are appended to the @skip_xxx_xxx_any arrays.
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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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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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# Command line options.
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my $help = 0;
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my $debug = 0;
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my @dont_walk = ();
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my @dont_parse = ();
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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/kernel/debug/tracing/trace_pipe',
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'/sys/kernel/security/apparmor/revision');
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# Do not parse thes 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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'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: $V
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Options:
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--dont-walk=<dir> Don't walk tree starting at <dir>.
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--dont-parse=<file> Don't parse <file>.
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-d, --debug Display debugging output.
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-h, --help, --version Display this help and exit.
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If an absolute path is passed to --dont_XXX then this path is skipped. If a
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single filename is passed then this file/directory will be skipped when
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appearing under any subdirectory.
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Example:
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# Just scan dmesg output.
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scripts/leaking_addresses.pl --dont_walk_abs /proc --dont_walk_abs /sys
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Scans the running (64 bit) kernel for potential leaking addresses.
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EOM
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exit($exitcode);
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}
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GetOptions(
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'dont-walk=s' => \@dont_walk,
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'dont-parse=s' => \@dont_parse,
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'd|debug' => \$debug,
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'h|help' => \$help,
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'version' => \$help
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) or help(1);
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help(0) if ($help);
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push_to_global();
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parse_dmesg();
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walk(@DIRS);
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exit 0;
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sub debug_arrays
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{
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print 'dirs_any: ' . join(", ", @skip_walk_dirs_any) . "\n";
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print 'dirs_abs: ' . join(", ", @skip_walk_dirs_abs) . "\n";
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print 'parse_any: ' . join(", ", @skip_parse_files_any) . "\n";
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print 'parse_abs: ' . join(", ", @skip_parse_files_abs) . "\n";
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}
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sub dprint
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{
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printf(STDERR @_) if $debug;
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}
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sub push_in_abs_any
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{
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my ($in, $abs, $any) = @_;
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foreach my $path (@$in) {
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if (File::Spec->file_name_is_absolute($path)) {
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push @$abs, $path;
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} elsif (index($path,'/') == -1) {
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push @$any, $path;
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} else {
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print 'path error: ' . $path;
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}
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}
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}
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# Push command line options to global arrays.
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sub push_to_global
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{
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push_in_abs_any(\@dont_walk, \@skip_walk_dirs_abs, \@skip_walk_dirs_any);
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push_in_abs_any(\@dont_parse, \@skip_parse_files_abs, \@skip_parse_files_any);
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}
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sub is_false_positive
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{
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my ($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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# 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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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 $address = '\b(0x)?ffff[[:xdigit:]]{12}\b';
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# Signal masks.
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if ($line =~ '^SigBlk:' 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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$line =~ '\b[[:xdigit:]]{14} [[:xdigit:]]{16} [[:xdigit:]]{16}\b') {
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return 0;
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}
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while (/($address)/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($path, \@skip_parse_files_abs, \@skip_parse_files_any);
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}
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sub parse_file
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{
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my ($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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my %seen;
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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, $path;
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} else {
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parse_file($path);
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}
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}
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}
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}
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