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Message-ID: <1513569287.8041.8.camel@gmail.com>
Date: Mon, 18 Dec 2017 09:24:47 +0530
From: kaiwan.billimoria@...il.com
To: "Tobin C. Harding" <me@...in.cc>
Cc: linux-kernel@...r.kernel.org, "kernel-hardening@...ts.openwall.com"
<kernel-hardening@...ts.openwall.com>
Subject: [PATCH] leaking_addresses: add generic 32-bit support
The script attempts to detect the architecture it's running upon; as of now,
we explicitly support x86_64, PPC64 and x86_32.
If it's one of them, we proceed "normally". If we fail to detect the arch,
we fallback to 64-bit scanning, unless the user has passed either of these
option switches: "--32-bit" and/or "--page-offset-32bit=<val>".
If so, we switch to scanning for leaked addresses based on the value of
PAGE_OFFSET (via an auto-detected or fallback mechanism).
As of now, we have code (or "rules") to detect special cases for x86_64 and ppc64
(in the get_address_re sub). Also, we now have also builtin "stubs", for lack of a better term,
where additional rules for other 64-bit arch's can be plugged in, in future,
as applicable.
Signed-off-by: Kaiwan N Billimoria <kaiwan.billimoria@...il.com>
---
This is a patch based on Tobin's latest tree, 'leaks' branch.
Applies on top of commit 6c3942594657 (leaking_addresses: add support for 5 page table levels (origin/leaks))
Thanks,
Kaiwan.
scripts/leaking_addresses.pl | 213 +++++++++++++++++++++++++++++++++++++------
1 file changed, 184 insertions(+), 29 deletions(-)
diff --git a/scripts/leaking_addresses.pl b/scripts/leaking_addresses.pl
index a29e13e577a7..a667f243c95b 100755
--- a/scripts/leaking_addresses.pl
+++ b/scripts/leaking_addresses.pl
@@ -1,10 +1,10 @@
#!/usr/bin/env perl
#
# (c) 2017 Tobin C. Harding <me@...in.cc>
-
+# (c) 2017 Kaiwan N Billimoria <kaiwan.billimoria@...il.com>
# 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 kernel for potential leaking addresses.
# - Scans dmesg output.
# - Walks directory tree and parses each file (for each directory in @DIRS).
#
@@ -35,7 +35,7 @@ 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');
+my @SUPPORTED_ARCHITECTURES = ('x86_64', 'ppc64', 'i[3456]86');
# Command line options.
my $help = 0;
@@ -48,7 +48,9 @@ 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_32_bit = 0; # Detect 32-bit kernel leaking addresses.
+my $page_offset_32bit = 0; # 32-bit: value of CONFIG_PAGE_OFFSET.
+my $kernel_config_file = ""; # Kernel configuration file.
# Do not parse these files (absolute path).
my @skip_parse_files_abs = ('/proc/kmsg',
@@ -97,17 +99,19 @@ Version: $V
Options:
- -o, --output-raw=<file> Save results for future processing.
- -i, --input-raw=<file> Read results from file instead of scanning.
- --raw Show raw results (default).
- --suppress-dmesg Do not show dmesg results.
- --squash-by-path Show one result per unique path.
- --squash-by-filename Show one result per unique filename.
- --kernel-config-file=<file> Kernel configuration file (e.g /boot/config)
- -d, --debug Display debugging output.
- -h, --help, --versionq Display this help and exit.
+ -o, --output-raw=<file> Save results for future processing.
+ -i, --input-raw=<file> Read results from file instead of scanning.
+ --raw Show raw results (default).
+ --suppress-dmesg Do not show dmesg results.
+ --squash-by-path Show one result per unique path.
+ --squash-by-filename Show one result per unique filename.
+ --32-bit Detect 32-bit kernel leaking addresses.
+ --page-offset-32bit=<hex> PAGE_OFFSET value (for 32-bit kernels).
+ --kernel-config-file=<file> Kernel configuration file (e.g /boot/config).
+ -d, --debug Display debugging output.
+ -h, --help, --version Display this help and exit.
-Scans the running (64 bit) kernel for potential leaking addresses.
+Scans the running kernel for potential leaking addresses.
EOM
exit($exitcode);
@@ -123,7 +127,9 @@ 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_32_bit,
+ 'page-offset-32bit=o' => \$page_offset_32bit,
+ 'kernel-config-file=s' => \$kernel_config_file,
) or help(1);
help(0) if ($help);
@@ -139,11 +145,16 @@ if (!$input_raw and ($squash_by_path or $squash_by_filename)) {
exit(128);
}
-if (!is_supported_architecture()) {
- printf "\nScript does not support your architecture, sorry.\n";
- printf "\nCurrently we support: \n\n";
- foreach(@SUPPORTED_ARCHITECTURES) {
- printf "\t%s\n", $_;
+show_detected_architecture() if $debug;
+
+if (!is_known_architecture()) {
+ printf STDERR "\n*** WARNING! Script does not recognize your architecture ***\n";
+ if ($opt_32_bit or $page_offset_32bit) {
+ printf STDERR "Scanning for 32-bit leaking kernel addresses\n\n";
+ } else {
+ printf STDERR "Scanning for 64-bit leaking kernel addresses\n";
+ printf STDERR "If you\'d rather scan for 32-bit addresses, use the ";
+ printf STDERR "--32-bit (and --page-offset-32bit=) option switch(es).\n\n";
}
my $archname = $Config{archname};
@@ -168,9 +179,14 @@ sub dprint
printf(STDERR @_) if $debug;
}
-sub is_supported_architecture
+sub is_known_architecture
+{
+ return (is_64bit() or is_ix86_32());
+}
+
+sub is_64bit
{
- return (is_x86_64() or is_ppc64());
+ return (is_x86_64() or is_ppc64() or is_arm64() or is_mips64());
}
sub is_x86_64
@@ -193,6 +209,50 @@ sub is_ppc64
return 0;
}
+sub is_arm64
+{
+ if (`uname -m` eq "aarch64") {
+ return 1;
+ }
+ return 0;
+}
+
+sub is_mips64
+{
+ if (`uname -m` eq "mips64") {
+ return 1;
+ }
+ return 0;
+}
+
+sub is_ix86_32
+{
+ my $archname = $Config{archname};
+
+ if ($archname =~ m/i[3456]86-linux/) {
+ return 1;
+ }
+ return 0;
+}
+
+sub show_detected_architecture
+{
+ printf "Detected architecture: ";
+ if (is_ix86_32()) {
+ printf "32 bit x86\n";
+ } elsif (is_x86_64()) {
+ printf "x86_64\n";
+ } elsif (is_ppc64()) {
+ printf "ppc64\n";
+ } elsif (is_arm64()) {
+ printf "ARM64\n";
+ } elsif (is_mips64()) {
+ printf "MIPS64\n";
+ } else {
+ printf "failed to detect architecture\n"
+ }
+}
+
# gets config option value from kernel config file
sub get_kernel_config_option
{
@@ -220,7 +280,8 @@ sub get_kernel_config_option
}
foreach my $file (@config_files) {
- dprint("parsing config file: %s\n", $file);
+ printf("file: %s\n", $file) if $debug;
+
$value = option_from_file($option, $file);
if ($value ne "") {
last;
@@ -258,6 +319,14 @@ sub is_false_positive
{
my ($match) = @_;
+ # 32 bit architectures, actual or forced
+
+ if (!is_64bit() and ($opt_32_bit or $page_offset_32bit)) {
+ return is_false_positive_32bit($match);
+ }
+
+ # 64 bit architectures
+
if ($match =~ '\b(0x)?(f|F){16}\b' or
$match =~ '\b(0x)?0{16}\b') {
return 1;
@@ -281,6 +350,91 @@ sub is_in_vsyscall_memory_region
return ($hex >= $region_min and $hex <= $region_max);
}
+sub is_false_positive_32bit
+{
+ my ($match) = @_;
+ state $page_offset = get_page_offset(); # only gets called once
+
+ if ($match =~ '\b(0x)?(f|F){8}\b') {
+ return 1;
+ }
+
+ my $addr32 = eval hex($match);
+ if ($addr32 < $page_offset) {
+ return 1;
+ }
+
+ return 0;
+}
+
+sub get_page_offset
+{
+ my $page_offset;
+ my $default_offset = hex("0xc0000000");
+ my @config_files;
+
+ # Allow --page-offset-32bit to override.
+ if ($page_offset_32bit != 0) {
+ return $page_offset_32bit;
+ }
+
+ # Allow --kernel-config-file to override.
+ if ($kernel_config_file ne "") {
+ @config_files = ($kernel_config_file);
+ } else {
+ my $config_file = '/boot/config-' . `uname -r`;
+ @config_files = ($config_file, '/boot/config');
+ }
+
+ if (-R "/proc/config.gz") {
+ my $tmp_file = "/tmp/tmpkconf";
+ if (system("gunzip < /proc/config.gz > $tmp_file")) {
+ dprint " parse_kernel_config: system(gunzip...) failed\n";
+ system("rm -f $tmp_file 2>/dev/null");
+ } else {
+ $page_offset = parse_kernel_config_file($tmp_file);
+ system("rm -f $tmp_file");
+ if ($page_offset ne "") {
+ return hex($page_offset);
+ }
+ }
+ }
+
+ foreach my $config_file (@config_files) {
+ chomp $config_file;
+ $page_offset = parse_kernel_config_file($config_file);
+ if ($page_offset ne "") {
+ return hex($page_offset);
+ }
+ }
+
+ printf STDERR "\nFailed to parse kernel config files\n";
+ printf STDERR "*** NOTE ***\n";
+ printf STDERR "Falling back to PAGE_OFFSET = %#x\n\n", $default_offset;
+
+ return $default_offset;
+}
+
+sub parse_kernel_config_file
+{
+ my ($file) = @_;
+ my $config = 'CONFIG_PAGE_OFFSET';
+ my $str = "";
+ my $val = "";
+
+ open(my $fh, "<", $file) or return "";
+ while (my $line = <$fh> ) {
+ if ($line =~ /^$config/) {
+ ($str, $val) = split /=/, $line;
+ chomp($val);
+ last;
+ }
+ }
+
+ close $fh;
+ return $val;
+}
+
# True if argument potentially contains a kernel address.
sub may_leak_address
{
@@ -300,7 +454,7 @@ sub may_leak_address
}
$address_re = get_address_re();
- dprint("Kernel address regular expression: %s\n", $address_re);
+# dprint("Kernel address regular expression: %s\n", $address_re);
while (/($address_re)/g) {
if (!is_false_positive($1)) {
@@ -313,16 +467,17 @@ sub may_leak_address
sub get_address_re
{
- my $re;
+ my $re = "";
if (is_x86_64()) {
$re = get_x86_64_re();
} elsif (is_ppc64()) {
$re = '\b(0x)?[89abcdef]00[[:xdigit:]]{13}\b';
- }
-
- if ($re eq "") {
- print STDERR "$0: failed to build kernel address regular expression\n";
+ ###
+ # Any special cases for other arch's go below this line
+ ###
+ } else { # nothing? then we assume it's a generic 32-bit
+ $re = '\b(0x)?[[:xdigit:]]{8}\b';
}
return $re;
--
2.14.3
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