From patchwork Mon Nov 6 05:19:27 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tobin Harding X-Patchwork-Id: 10042607 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 8A86D601EB for ; Mon, 6 Nov 2017 05:19:57 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7C43728AEB for ; Mon, 6 Nov 2017 05:19:57 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6F08C28B0B; Mon, 6 Nov 2017 05:19:57 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.1 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_MED,T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id 9F4F328AEB for ; Mon, 6 Nov 2017 05:19:54 +0000 (UTC) Received: (qmail 24181 invoked by uid 550); 6 Nov 2017 05:19:51 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 24160 invoked from network); 6 Nov 2017 05:19:50 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=tobin.cc; h=cc :date:from:message-id:subject:to:x-me-sender:x-me-sender :x-sasl-enc; s=fm1; bh=akF+/+FTR/oEQtc6OfT1e6vBgM+BpC1ebJhxpHxrj jw=; b=NJmDltCvvcSeet5gAdfWnJYkU2UkSzXcMxcF9vKvBCoiR19yL9gMk0zPV br/BNVVoDHY/2wkxnpl21aCx/KWG2CsyjDZYjqWjI5kjmIbocH7Lvp0AGsZT8qmd nRtu4AyEt7yQ7nJ06dhVZ7SaaMeLKPA5lAhspQzPxELrADfEgQ69T59jq01qdZBH v8nbKjcdfuTzcYUdP0bEvVzjPZ9ir+LX45FkH3Nug+0DVGN0CHB7rQwLeDxVOyyH TShlgWy9pFlRczlZrBtGU3K6ujA6B1zFh+Hp9U7D20NhxtcL0S64i0nQrHeqhJsh qjO27f7bK/HcKkcu62GiybPy0Yinw== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:date:from:message-id:subject:to :x-me-sender:x-me-sender:x-sasl-enc; s=fm1; bh=akF+/+FTR/oEQtc6O fT1e6vBgM+BpC1ebJhxpHxrjjw=; b=GDd+q1RkFuqDfGEh4ZII09wCTcH9Dc0x3 HO2rSBdItfQUjkh/klx6dIXMj5lyEZmywnv2cRla94Zfh0cDAfKl9avzpdnp9l2d mEvSm3tXBITbIFiwAf+truaxRnRMwWQ1nzFMfjdPuRXPqaZUXK3WEmoC9AGr3cUm f/Ll9F702Muy5dxINf6ul1CPZ4GYFI8ugzZqjoRXL5owFKp7aeA/EhUjaitrRy9O HATASU9k6Wd3FLW3jtD57zYZNela1MRSwm5ehuGIsdeGEpkVOb5vblL3T7uYDpYd RuoBz+ASDA0jSNhqR5x1tDLZMcbaqu+MVvlfnCi51lteeERG64uGQ== X-ME-Sender: From: "Tobin C. Harding" To: kernel-hardening@lists.openwall.com Cc: "Tobin C. Harding" , "Jason A. Donenfeld" , Theodore Ts'o , Linus Torvalds , Kees Cook , Paolo Bonzini , Tycho Andersen , "Roberts, William C" , Tejun Heo , Jordan Glover , Greg KH , Petr Mladek , Joe Perches , Ian Campbell , Sergey Senozhatsky , Catalin Marinas , Will Deacon , Steven Rostedt , Chris Fries , Dave Weinstein , Daniel Micay , Djalal Harouni , linux-kernel@vger.kernel.org Date: Mon, 6 Nov 2017 16:19:27 +1100 Message-Id: <1509945567-11801-1-git-send-email-me@tobin.cc> X-Mailer: git-send-email 2.7.4 Subject: [kernel-hardening] [PATCH v3] scripts: add leaking_addresses.pl X-Virus-Scanned: ClamAV using ClamSMTP Currently we are leaking addresses from the kernel to user space. This script is an attempt to find some of those leakages. Script parses `dmesg` output and /proc and /sys files for hex strings that look like kernel addresses. Only works for 64 bit kernels, the reason being that kernel addresses on 64 bit kernels have 'ffff' as the leading bit pattern making greping possible. On 32 kernels we don't have this luxury. Scripts is _slightly_ smarter than a straight grep, we check for false positives (all 0's or all 1's, and vsyscall start/finish addresses). Signed-off-by: Tobin C. Harding --- v3: - Iterate matches to check for results instead of matching input line against false positives i.e catch lines that contain results as well as false positives. v2: - Add regex's to prevent false positives. - Clean up white space. MAINTAINERS | 5 + scripts/leaking_addresses.pl | 306 +++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 311 insertions(+) create mode 100755 scripts/leaking_addresses.pl diff --git a/MAINTAINERS b/MAINTAINERS index e652a3e2929d..c1ad6d133a57 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -7745,6 +7745,11 @@ S: Maintained F: Documentation/scsi/53c700.txt F: drivers/scsi/53c700* +LEAKING_ADDRESSES +M: Tobin C. Harding +S: Maintained +F: scripts/leaking_addresses.pl + LED SUBSYSTEM M: Richard Purdie M: Jacek Anaszewski diff --git a/scripts/leaking_addresses.pl b/scripts/leaking_addresses.pl new file mode 100755 index 000000000000..1487a75cfc52 --- /dev/null +++ b/scripts/leaking_addresses.pl @@ -0,0 +1,306 @@ +#!/usr/bin/env perl +# +# (c) 2017 Tobin C. Harding +# Licensed under the terms of the GNU GPL License version 2 +# +# leaking_addresses.pl: Scan 64 bit kernel for potential leaking addresses. +# - Scans dmesg output. +# - Walks directory tree and parses each file (for each directory in @DIRS). +# +# You can configure the behaviour of the script; +# +# - By adding paths, for directories you do not want to walk; +# absolute paths: @skip_walk_dirs_abs +# directory names: @skip_walk_dirs_any +# +# - By adding paths, for files you do not want to parse; +# absolute paths: @skip_parse_files_abs +# file names: @skip_parse_files_any +# +# The use of @skip_xxx_xxx_any causes files to be skipped where ever they occur. +# For example adding 'fd' to @skip_walk_dirs_any causes the fd/ directory to be +# skipped for all PID sub-directories of /proc +# +# The same thing can be achieved by passing command line options to --dont-walk +# and --dont-parse. If absolute paths are supplied to these options they are +# appended to the @skip_xxx_xxx_abs arrays. If file names are supplied to these +# options, they are appended to the @skip_xxx_xxx_any arrays. +# +# Use --debug to output path before parsing, this is useful to find files that +# cause the script to choke. +# +# You may like to set kptr_restrict=2 before running script +# (see Documentation/sysctl/kernel.txt). + +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); + +my $P = $0; +my $V = '0.01'; + +# Directories to scan. +my @DIRS = ('/proc', '/sys'); + +# Command line options. +my $help = 0; +my $debug = 0; +my @dont_walk = (); +my @dont_parse = (); + +# Do not parse these files (absolute path). +my @skip_parse_files_abs = ('/proc/kmsg', + '/proc/kcore', + '/proc/fs/ext4/sdb1/mb_groups', + '/proc/1/fd/3', + '/sys/kernel/debug/tracing/trace_pipe', + '/sys/kernel/security/apparmor/revision'); + +# Do not parse thes files under any subdirectory. +my @skip_parse_files_any = ('0', + '1', + '2', + 'pagemap', + 'events', + 'access', + 'registers', + 'snapshot_raw', + 'trace_pipe_raw', + 'ptmx', + 'trace_pipe'); + +# Do not walk these directories (absolute path). +my @skip_walk_dirs_abs = (); + +# Do not walk these directories under any subdirectory. +my @skip_walk_dirs_any = ('self', + 'thread-self', + 'cwd', + 'fd', + 'stderr', + 'stdin', + 'stdout'); + +sub help +{ + my ($exitcode) = @_; + + print << "EOM"; +Usage: $P [OPTIONS] +Version: $V + +Options: + + --dont-walk= Don't walk tree starting at . + --dont-parse= Don't parse . + -d, --debug Display debugging output. + -h, --help, --version Display this help and exit. + +If an absolute path is passed to --dont_XXX then this path is skipped. If a +single filename is passed then this file/directory will be skipped when +appearing under any subdirectory. + +Example: + + # Just scan dmesg output. + scripts/leaking_addresses.pl --dont_walk_abs /proc --dont_walk_abs /sys + +Scans the running (64 bit) kernel for potential leaking addresses. + +EOM + exit($exitcode); +} + +GetOptions( + 'dont-walk=s' => \@dont_walk, + 'dont-parse=s' => \@dont_parse, + 'd|debug' => \$debug, + 'h|help' => \$help, + 'version' => \$help +) or help(1); + +help(0) if ($help); + +push_to_global(); + +parse_dmesg(); +walk(@DIRS); + +exit 0; + +sub debug_arrays +{ + print 'dirs_any: ' . join(", ", @skip_walk_dirs_any) . "\n"; + print 'dirs_abs: ' . join(", ", @skip_walk_dirs_abs) . "\n"; + print 'parse_any: ' . join(", ", @skip_parse_files_any) . "\n"; + print 'parse_abs: ' . join(", ", @skip_parse_files_abs) . "\n"; +} + +sub dprint +{ + printf(STDERR @_) if $debug; +} + +sub push_in_abs_any +{ + my ($in, $abs, $any) = @_; + + foreach my $path (@$in) { + if (File::Spec->file_name_is_absolute($path)) { + push @$abs, $path; + } elsif (index($path,'/') == -1) { + push @$any, $path; + } else { + print 'path error: ' . $path; + } + } +} + +# Push command line options to global arrays. +sub push_to_global +{ + push_in_abs_any(\@dont_walk, \@skip_walk_dirs_abs, \@skip_walk_dirs_any); + push_in_abs_any(\@dont_parse, \@skip_parse_files_abs, \@skip_parse_files_any); +} + +sub is_false_positive +{ + my ($match) = @_; + + if ($match =~ '\b(0x)?(f|F){16}\b' or + $match =~ '\b(0x)?0{16}\b') { + return 1; + } + + # vsyscall memory region, we should probably check against a range here. + if ($match =~ '\bf{10}600000\b' or + $match =~ '\bf{10}601000\b') { + return 1; + } + + return 0; +} + +# True if argument potentially contains a kernel address. +sub may_leak_address +{ + my ($line) = @_; + my $address = '\b(0x)?ffff[[:xdigit:]]{12}\b'; + + # Signal masks. + if ($line =~ '^SigBlk:' or + $line =~ '^SigCgt:') { + return 0; + } + + if ($line =~ '\bKEY=[[:xdigit:]]{14} [[:xdigit:]]{16} [[:xdigit:]]{16}\b' or + $line =~ '\b[[:xdigit:]]{14} [[:xdigit:]]{16} [[:xdigit:]]{16}\b') { + return 0; + } + + while (/($address)/g) { + if (!is_false_positive($1)) { + return 1; + } + } + + return 0; +} + +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, $paths_abs, $paths_any) = @_; + + foreach (@$paths_abs) { + return 1 if (/^$path$/); + } + + my($filename, $dirs, $suffix) = fileparse($path); + foreach (@$paths_any) { + return 1 if (/^$filename$/); + } + + return 0; +} + +sub skip_parse +{ + my ($path) = @_; + return skip($path, \@skip_parse_files_abs, \@skip_parse_files_any); +} + +sub parse_file +{ + my ($file) = @_; + + if (! -R $file) { + return; + } + + if (skip_parse($file)) { + dprint "skipping file: $file\n"; + return; + } + dprint "parsing: $file\n"; + + open my $fh, "<", $file or return; + while ( <$fh> ) { + if (may_leak_address($_)) { + print $file . ': ' . $_; + } + } + close $fh; +} + + +# True if we should skip walking this directory. +sub skip_walk +{ + my ($path) = @_; + return skip($path, \@skip_walk_dirs_abs, \@skip_walk_dirs_any) +} + +# Recursively walk directory tree. +sub walk +{ + my @dirs = @_; + my %seen; + + while (my $pwd = shift @dirs) { + next if (skip_walk($pwd)); + 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); + + if (-d $path) { + push @dirs, $path; + } else { + parse_file($path); + } + } + } +} +