diff options
Diffstat (limited to 'scripts')
| -rwxr-xr-x | scripts/leaking_addresses.pl | 372 |
1 files changed, 259 insertions, 113 deletions
diff --git a/scripts/leaking_addresses.pl b/scripts/leaking_addresses.pl index bc5788000018..6a897788f5a7 100755 --- a/scripts/leaking_addresses.pl +++ b/scripts/leaking_addresses.pl @@ -3,15 +3,20 @@ # (c) 2017 Tobin C. Harding <me@tobin.cc> # Licensed under the terms of the GNU GPL License version 2 # -# leaking_addresses.pl: Scan 64 bit kernel for potential leaking addresses. +# 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. + # -# You may like to set kptr_restrict=2 before running script -# (see Documentation/sysctl/kernel.txt). +# 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; @@ -22,9 +27,10 @@ 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; -my $V = '0.01'; # Directories to scan. my @DIRS = ('/proc', '/sys'); @@ -32,10 +38,9 @@ my @DIRS = ('/proc', '/sys'); # Timer for parsing each file, in seconds. my $TIMEOUT = 10; -# Script can only grep for kernel addresses on the following architectures. If -# your architecture is not listed here and has a grep'able kernel address please -# consider submitting a patch. -my @SUPPORTED_ARCHITECTURES = ('x86_64', 'ppc64'); +# 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; @@ -43,46 +48,34 @@ 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. - -# 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/firmware/devicetree', - '/proc/device-tree', - '/sys/kernel/debug/tracing/trace_pipe', - '/sys/kernel/security/apparmor/revision'); - -# Do not parse these 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', - 'usbmon', - 'stderr', - 'stdin', - 'stdout'); +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 { @@ -91,31 +84,22 @@ sub help print << "EOM"; Usage: $P [OPTIONS] -Version: $V 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. - -d, --debug Display debugging output. - -h, --help, --version Display this help and exit. - -Examples: - - # Scan kernel and dump raw results. - $0 - - # Scan kernel and save results to file. - $0 --output-raw scan.out + -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. - # View summary report. - $0 --input-raw scan.out --squash-by-filename - -Scans the running (64 bit) kernel for potential leaking addresses. +Scans the running kernel for potential leaking addresses. EOM exit($exitcode); @@ -131,6 +115,9 @@ GetOptions( '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 ($help); @@ -146,16 +133,19 @@ if (!$input_raw and ($squash_by_path or $squash_by_filename)) { exit(128); } -if (!is_supported_architecture()) { +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 = $Config{archname}; - printf "\n\$ perl -MConfig -e \'print \"\$Config{archname}\\n\"\'\n"; - printf "%s\n", $archname; + my $archname = `uname -m`; + printf("Machine hardware name (`uname -m`): %s\n", $archname); exit(129); } @@ -177,49 +167,183 @@ sub dprint sub is_supported_architecture { - return (is_x86_64() or is_ppc64()); + return (is_x86_64() or is_ppc64() or is_ix86_32()); } -sub is_x86_64 +sub is_32bit { - my $archname = $Config{archname}; - - if ($archname =~ m/x86_64/) { + # Allow --32-bit or --page-offset-32-bit to override + if ($opt_32bit or $page_offset_32bit) { return 1; } - return 0; + + 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 { - my $archname = $Config{archname}; + state $is = is_arch('ppc64'); + return $is; +} - if ($archname =~ m/powerpc/ and $archname =~ m/64/) { - return 1; +# Gets config option value from kernel config file. +# Returns "" on error or if config option not found. +sub get_kernel_config_option +{ + my ($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'); } - return 0; + + 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 $match =~ '\b(0x)?0{16}\b') { return 1; } - if (is_x86_64) { - # vsyscall memory region, we should probably check against a range here. - if ($match =~ '\bf{10}600000\b' or - $match =~ '\bf{10}601000\b') { - return 1; - } + if (is_x86_64() and is_in_vsyscall_memory_region($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 { @@ -238,14 +362,8 @@ sub may_leak_address return 0; } - # One of these is guaranteed to be true. - if (is_x86_64()) { - $address_re = '\b(0x)?ffff[[:xdigit:]]{12}\b'; - } elsif (is_ppc64()) { - $address_re = '\b(0x)?[89abcdef]00[[:xdigit:]]{13}\b'; - } - - while (/($address_re)/g) { + $address_re = get_address_re(); + while ($line =~ /($address_re)/g) { if (!is_false_positive($1)) { return 1; } @@ -254,6 +372,31 @@ sub may_leak_address 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 $cmd, '-|', 'dmesg'; @@ -268,26 +411,20 @@ sub parse_dmesg # True if we should skip this path. sub skip { - my ($path, $paths_abs, $paths_any) = @_; + my ($path) = @_; - foreach (@$paths_abs) { + foreach (@skip_abs) { return 1 if (/^$path$/); } my($filename, $dirs, $suffix) = fileparse($path); - foreach (@$paths_any) { + foreach (@skip_any) { return 1 if (/^$filename$/); } return 0; } -sub skip_parse -{ - my ($path) = @_; - return skip($path, \@skip_parse_files_abs, \@skip_parse_files_any); -} - sub timed_parse_file { my ($file) = @_; @@ -313,11 +450,9 @@ sub parse_file return; } - if (skip_parse($file)) { - dprint "skipping file: $file\n"; + if (! -T $file) { return; } - dprint "parsing: $file\n"; open my $fh, "<", $file or return; while ( <$fh> ) { @@ -328,12 +463,14 @@ sub parse_file close $fh; } - -# True if we should skip walking this directory. -sub skip_walk +# Checks if the actual path name is leaking a kernel address. +sub check_path_for_leaks { my ($path) = @_; - return skip($path, \@skip_walk_dirs_abs, \@skip_walk_dirs_any) + + if (may_leak_address($path)) { + printf("Path name may contain address: $path\n"); + } } # Recursively walk directory tree. @@ -342,7 +479,6 @@ sub walk my @dirs = @_; while (my $pwd = shift @dirs) { - next if (skip_walk($pwd)); next if (!opendir(DIR, $pwd)); my @files = readdir(DIR); closedir(DIR); @@ -353,11 +489,21 @@ sub walk 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, $path; - } else { - timed_parse_file($path); + next; } + + dprint "parsing: $path\n"; + timed_parse_file($path); } } } |