From 1410fe4eea22959bd31c05e4c1846f1718300bde Mon Sep 17 00:00:00 2001 From: "Tobin C. Harding" Date: Mon, 29 Jan 2018 15:00:16 +1100 Subject: leaking_addresses: add 32-bit support Currently script only supports x86_64 and ppc64. It would be nice to be able to scan 32-bit machines also. We can add support for 32-bit architectures by modifying how we check for false positives, taking advantage of the page offset used by the kernel, and using the correct regular expression. Support for 32-bit machines is enabled by the observation that the kernel addresses on 32-bit machines are larger [in value] than the page offset. We can use this to filter false positives when scanning the kernel for leaking addresses. Programmatic determination of the running architecture is not immediately obvious (current 32-bit machines return various strings from `uname -m`). We therefore provide a flag to enable scanning of 32-bit kernels. Also we can check the kernel config file for the offset and if not found default to 0xc0000000. A command line option to parse in the page offset is also provided. We do automatically detect architecture if running on ix86. Add support for 32-bit kernels. Add a command line option for page offset. Suggested-by: Kaiwan N Billimoria Signed-off-by: Tobin C. Harding --- scripts/leaking_addresses.pl | 93 ++++++++++++++++++++++++++++++++++++++------ 1 file changed, 82 insertions(+), 11 deletions(-) diff --git a/scripts/leaking_addresses.pl b/scripts/leaking_addresses.pl index e5b418cca185..05906f6cf6b9 100755 --- a/scripts/leaking_addresses.pl +++ b/scripts/leaking_addresses.pl @@ -3,7 +3,7 @@ # (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. +# 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). # @@ -31,10 +31,9 @@ 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; @@ -46,6 +45,8 @@ 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. my $kernel_config_file = ""; # Kernel configuration file. +my $opt_32bit = 0; # Scan 32-bit kernel. +my $page_offset_32bit = 0; # Page offset for 32-bit kernel. # Do not parse these files (absolute path). my @skip_parse_files_abs = ('/proc/kmsg', @@ -101,10 +102,12 @@ Options: --squash-by-path Show one result per unique path. --squash-by-filename Show one result per unique filename. --kernel-config-file= Kernel configuration file (e.g /boot/config) + --32-bit Scan 32-bit kernel. + --page-offset-32-bit=o Page offset (for 32-bit kernel 0xABCD1234). -d, --debug Display debugging output. -h, --help, --version Display this help and exit. -Scans the running (64 bit) kernel for potential leaking addresses. +Scans the running kernel for potential leaking addresses. EOM exit($exitcode); @@ -121,6 +124,8 @@ GetOptions( '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 ($help); @@ -136,7 +141,7 @@ if (!$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) { @@ -144,6 +149,9 @@ if (!is_supported_architecture()) { } 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=\n\n"); + my $archname = `uname -m`; printf("Machine hardware name (`uname -m`): %s\n", $archname); @@ -167,7 +175,28 @@ sub dprint sub is_supported_architecture { - return (is_x86_64() or is_ppc64()); + return (is_x86_64() or is_ppc64() or is_ix86_32()); +} + +sub is_32bit +{ + # Allow --32-bit or --page-offset-32-bit to override + if ($opt_32bit or $page_offset_32bit) { + return 1; + } + + return is_ix86_32(); +} + +sub is_ix86_32 +{ + my $arch = `uname -m`; + + chomp $arch; + if ($arch =~ m/i[3456]86/) { + return 1; + } + return 0; } sub is_arch @@ -258,6 +287,12 @@ 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 $match =~ '\b(0x)?0{16}\b') { return 1; @@ -270,6 +305,40 @@ sub is_false_positive return 0; } +sub is_false_positive_32bit +{ + my ($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) = @_; @@ -311,11 +380,13 @@ sub may_leak_address sub get_address_re { - if (is_x86_64()) { - return get_x86_64_re(); - } elsif (is_ppc64()) { + 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 -- cgit v1.2.3-58-ga151