From patchwork Thu Oct 26 06:21:03 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tobin Harding X-Patchwork-Id: 10027509 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 3154260375 for ; Thu, 26 Oct 2017 06:21:28 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1B6321FFE5 for ; Thu, 26 Oct 2017 06:21:28 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 0FCF728D20; Thu, 26 Oct 2017 06:21:28 +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 739291FFE5 for ; Thu, 26 Oct 2017 06:21:25 +0000 (UTC) Received: (qmail 23656 invoked by uid 550); 26 Oct 2017 06:21:24 -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 23632 invoked from network); 26 Oct 2017 06:21:23 -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=2XTY8ePhovtOoMa2r0CXEd9YRjzAmSY/cKjm9eUjm FY=; b=hgpWAhAnSAjaOGyF00f8pfHlaXYxWjEfhwX45PS3B9cErRbmmVHkBcTBI Wl6AsPHmyNIzIL0T235oJ9lF/aEoeybF/XMhvl2iIb7t0u5/xGg8DJPyL9SF211w fJliVX16b2TJPUBru4UqdxRjZqaG0gZyEL/dqIn38GfWv84Mqvvc+Egj+P9XZJgs QGj+DCm3jt6ZhPsiP6EFx5IAVsWnbojR2ls+KNEJJtw7nAMyUKmtg2+h3nRVA8l4 f2vUuMcXH6zUTA36TJA6TqR+w2g2cPxyvxG/m0xJPQhWoQbXLYMA1EkqtrogVc9g fdviXHSe2VOoiWlv+Mv93Gm9l9GfQ== 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=2XTY8ePhovtOoMa2r 0CXEd9YRjzAmSY/cKjm9eUjmFY=; b=DPNFfOMCOPyMwffdTe+XCoBOaQBVfo2ND IghTreZF6DQKLf0S64Ysm2qUtf/tslGm8OVlz0xrXJgc/FuwDJJNM3j4G2+Pq0Go 7r4MKHQbK+GBJfoE/NFQ1Yz0HNTFWGKrhLZ1AgYDcrqGYwcF3cwf43eFdVJVK7RG jBqksonFRwqKSYN9eBG8GDFS8b1XySzO2cod0d/w3jFn5fM7VdQHBLg5XVIfMyyJ ROSM75gULLJfqybBoa4YROI5vdlkrjWNSRWTzB7VrYF6lBFVpaEPPZ032ZKhQEjH Ss/Z2nccczSM6K9JnN6TacWmiIxf59I2FEUBI1t3XKRhpvceq6npg== 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: Thu, 26 Oct 2017 17:21:03 +1100 Message-Id: <1508998863-14629-1-git-send-email-me@tobin.cc> X-Mailer: git-send-email 2.7.4 Subject: [kernel-hardening] [PATCH] 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 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. Signed-off-by: Tobin C. Harding --- Changes since RFC V2 - Refactor the code that skips directories and files into helper functions. - Add documentation. - Add an entry in MAINTAINERS. MAINTAINERS | 5 + scripts/leaking_addresses.pl | 282 +++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 287 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..430ff1b0c3ec --- /dev/null +++ b/scripts/leaking_addresses.pl @@ -0,0 +1,282 @@ +#!/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 $debug = 0; +my @dont_walk = (); +my @dont_parse = (); + +# Do not parse these files (ablosute path). +my @skip_parse_files_abs = ('/proc/kmsg', + '/proc/kcore', + '/proc/fs/ext4/sdb1/mb_groups', + '/proc/1/fd/3', + '/sys/kernel/debug/tracing/trace_pipe', + '/sys/kernel/security/apparmor/revision'); + +# Do not parse thes files under any subdirectory. +my @skip_parse_files_any = ('0', + '1', + '2', + 'pagemap', + 'events', + 'access', + 'registers', + 'snapshot_raw', + 'trace_pipe_raw', + 'ptmx', + 'trace_pipe'); + +# Do not walk these directories (absolute path). +my @skip_walk_dirs_abs = (); + +# Do not walk these directories under any subdirectory. +my @skip_walk_dirs_any = ('self', + 'thread-self', + 'cwd', + 'fd', + 'stderr', + 'stdin', + 'stdout'); + +sub help +{ + my ($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: ' . $path; + } + } +} + +# Push command line options to global arrays. +sub push_to_global +{ + push_in_abs_any(\@dont_walk, \@skip_walk_dirs_abs, \@skip_walk_dirs_any); + push_in_abs_any(\@dont_parse, \@skip_parse_files_abs, \@skip_parse_files_any); +} + +# True if argument potentially contains a kernel address. +sub may_leak_address +{ + my ($line) = @_; + + # Ignore false positives. + if ($line =~ '\b(0x)?(f|F){16}\b' or + $line =~ '\b(0x)?0{16}\b' or + $line =~ '\bKEY=[[:xdigit:]]{14} [[:xdigit:]]{16} [[:xdigit:]]{16}\b') { + return 0; + } + + # Potential kernel address. + if ($line =~ '\b(0x)?ffff[[:xdigit:]]{12}\b') { + 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); + } + } + } +} +