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![Ross Zwisler](/assets/img/avatar_default.png)
The canonical location for the tracefs filesystem is at /sys/kernel/tracing. But, from Documentation/trace/ftrace.rst: Before 4.1, all ftrace tracing control files were within the debugfs file system, which is typically located at /sys/kernel/debug/tracing. For backward compatibility, when mounting the debugfs file system, the tracefs file system will be automatically mounted at: /sys/kernel/debug/tracing scripts/leaking_addresses.pl only skipped this older debugfs path, so let's add the canonical path as well. Link: https://lkml.kernel.org/r/20230313211746.1541525-2-zwisler@kernel.org Cc: "Tobin C. Harding" <me@tobin.cc> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Shuah Khan <shuah@kernel.org> Acked-by: Tycho Andersen <tycho@tycho.pizza> Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Ross Zwisler <zwisler@google.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
648 lines
13 KiB
Perl
Executable file
648 lines
13 KiB
Perl
Executable file
#!/usr/bin/env perl
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# SPDX-License-Identifier: GPL-2.0-only
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#
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# (c) 2017 Tobin C. Harding <me@tobin.cc>
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#
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# leaking_addresses.pl: Scan the 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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# When the system is idle it is likely that most files under /proc/PID will be
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# identical for various processes. Scanning _all_ the PIDs under /proc is
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# unnecessary and implies that we are thoroughly scanning /proc. This is _not_
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# the case because there may be ways userspace can trigger creation of /proc
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# files that leak addresses but were not present during a scan. For these two
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# reasons we exclude all PID directories under /proc except '1/'
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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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use bigint qw/hex/;
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use feature 'state';
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my $P = $0;
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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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# Kernel addresses vary by architecture. We can only auto-detect the following
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# architectures (using `uname -m`). (flag --32-bit overrides auto-detection.)
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my @SUPPORTED_ARCHITECTURES = ('x86_64', 'ppc64', 'x86');
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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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my $kernel_config_file = ""; # Kernel configuration file.
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my $opt_32bit = 0; # Scan 32-bit kernel.
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my $page_offset_32bit = 0; # Page offset for 32-bit kernel.
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# Skip these absolute paths.
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my @skip_abs = (
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'/proc/kmsg',
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'/proc/device-tree',
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'/proc/1/syscall',
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'/sys/firmware/devicetree',
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'/sys/kernel/tracing/trace_pipe',
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'/sys/kernel/debug/tracing/trace_pipe',
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'/sys/kernel/security/apparmor/revision');
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# Skip these under any subdirectory.
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my @skip_any = (
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'pagemap',
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'events',
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'access',
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'registers',
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'snapshot_raw',
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'trace_pipe_raw',
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'ptmx',
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'trace_pipe',
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'fd',
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'usbmon');
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sub help
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{
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my ($exitcode) = @_;
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print << "EOM";
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Usage: $P [OPTIONS]
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Options:
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-o, --output-raw=<file> Save results for future processing.
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-i, --input-raw=<file> Read results from file instead of scanning.
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--raw Show raw results (default).
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--suppress-dmesg Do not show dmesg results.
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--squash-by-path Show one result per unique path.
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--squash-by-filename Show one result per unique filename.
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--kernel-config-file=<file> Kernel configuration file (e.g /boot/config)
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--32-bit Scan 32-bit kernel.
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--page-offset-32-bit=o Page offset (for 32-bit kernel 0xABCD1234).
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-d, --debug Display debugging output.
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-h, --help Display this help and exit.
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Scans the running kernel for potential leaking addresses.
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EOM
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exit($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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'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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'kernel-config-file=s' => \$kernel_config_file,
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'32-bit' => \$opt_32bit,
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'page-offset-32-bit=o' => \$page_offset_32bit,
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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() or $opt_32bit or $page_offset_32bit)) {
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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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printf("\n");
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printf("If you are running a 32-bit architecture you may use:\n");
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printf("\n\t--32-bit or --page-offset-32-bit=<page offset>\n\n");
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my $archname = `uname -m`;
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printf("Machine hardware name (`uname -m`): %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 $debug;
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}
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sub is_supported_architecture
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{
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return (is_x86_64() or is_ppc64() or is_ix86_32());
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}
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sub is_32bit
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{
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# Allow --32-bit or --page-offset-32-bit to override
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if ($opt_32bit or $page_offset_32bit) {
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return 1;
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}
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return is_ix86_32();
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}
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sub is_ix86_32
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{
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state $arch = `uname -m`;
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chomp $arch;
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if ($arch =~ m/i[3456]86/) {
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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_arch
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{
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my ($desc) = @_;
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my $arch = `uname -m`;
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chomp $arch;
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if ($arch eq $desc) {
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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_x86_64
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{
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state $is = is_arch('x86_64');
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return $is;
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}
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sub is_ppc64
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{
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state $is = is_arch('ppc64');
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return $is;
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}
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# Gets config option value from kernel config file.
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# Returns "" on error or if config option not found.
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sub get_kernel_config_option
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{
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my ($option) = @_;
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my $value = "";
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my $tmp_file = "";
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my @config_files;
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# Allow --kernel-config-file to override.
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if ($kernel_config_file ne "") {
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@config_files = ($kernel_config_file);
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} elsif (-R "/proc/config.gz") {
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my $tmp_file = "/tmp/tmpkconf";
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if (system("gunzip < /proc/config.gz > $tmp_file")) {
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dprint("system(gunzip < /proc/config.gz) failed\n");
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return "";
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} else {
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@config_files = ($tmp_file);
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}
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} else {
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my $file = '/boot/config-' . `uname -r`;
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chomp $file;
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@config_files = ($file, '/boot/config');
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}
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foreach my $file (@config_files) {
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dprint("parsing config file: $file\n");
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$value = option_from_file($option, $file);
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if ($value ne "") {
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last;
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}
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}
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if ($tmp_file ne "") {
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system("rm -f $tmp_file");
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}
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return $value;
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}
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# Parses $file and returns kernel configuration option value.
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sub option_from_file
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{
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my ($option, $file) = @_;
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my $str = "";
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my $val = "";
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open(my $fh, "<", $file) or return "";
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while (my $line = <$fh> ) {
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if ($line =~ /^$option/) {
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($str, $val) = split /=/, $line;
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chomp $val;
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last;
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}
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}
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close $fh;
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return $val;
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}
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sub is_false_positive
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{
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my ($match) = @_;
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if (is_32bit()) {
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return is_false_positive_32bit($match);
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}
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# 64 bit false positives.
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if ($match =~ '\b(0x)?(f|F){16}\b' or
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$match =~ '\b(0x)?0{16}\b') {
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return 1;
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}
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if (is_x86_64() and is_in_vsyscall_memory_region($match)) {
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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_32bit
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{
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my ($match) = @_;
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state $page_offset = get_page_offset();
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if ($match =~ '\b(0x)?(f|F){8}\b') {
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return 1;
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}
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if (hex($match) < $page_offset) {
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return 1;
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}
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return 0;
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}
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# returns integer value
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sub get_page_offset
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{
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my $page_offset;
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my $default_offset = 0xc0000000;
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# Allow --page-offset-32bit to override.
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if ($page_offset_32bit != 0) {
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return $page_offset_32bit;
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}
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$page_offset = get_kernel_config_option('CONFIG_PAGE_OFFSET');
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if (!$page_offset) {
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return $default_offset;
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}
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return $page_offset;
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}
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sub is_in_vsyscall_memory_region
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{
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my ($match) = @_;
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my $hex = hex($match);
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my $region_min = hex("0xffffffffff600000");
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my $region_max = hex("0xffffffffff601000");
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return ($hex >= $region_min and $hex <= $region_max);
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}
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# True if argument potentially contains a kernel address.
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sub may_leak_address
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{
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my ($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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$address_re = get_address_re();
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while ($line =~ /($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 get_address_re
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{
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if (is_ppc64()) {
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return '\b(0x)?[89abcdef]00[[:xdigit:]]{13}\b';
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} elsif (is_32bit()) {
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return '\b(0x)?[[:xdigit:]]{8}\b';
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}
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return get_x86_64_re();
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}
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sub get_x86_64_re
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{
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# We handle page table levels but only if explicitly configured using
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# CONFIG_PGTABLE_LEVELS. If config file parsing fails or config option
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# is not found we default to using address regular expression suitable
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# for 4 page table levels.
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state $ptl = get_kernel_config_option('CONFIG_PGTABLE_LEVELS');
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if ($ptl == 5) {
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return '\b(0x)?ff[[:xdigit:]]{14}\b';
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}
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return '\b(0x)?ffff[[:xdigit:]]{12}\b';
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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) = @_;
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foreach (@skip_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 (@skip_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 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 (! -T $file) {
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return;
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}
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open my $fh, "<", $file or return;
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while ( <$fh> ) {
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chomp;
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if (may_leak_address($_)) {
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printf("$file: $_\n");
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}
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}
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close $fh;
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}
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# Checks if the actual path name is leaking a kernel address.
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sub check_path_for_leaks
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{
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my ($path) = @_;
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if (may_leak_address($path)) {
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printf("Path name may contain address: $path\n");
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}
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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 (!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 $path);
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# skip /proc/PID except /proc/1
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next if (($path =~ /^\/proc\/[0-9]+$/) &&
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($path !~ /^\/proc\/1$/));
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next if (skip($path));
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check_path_for_leaks($path);
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if (-d $path) {
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push @dirs, $path;
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next;
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}
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dprint("parsing: $path\n");
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timed_parse_file($path);
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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)) {
|
|
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;
|
|
}
|