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Message-ID: <1511752336.31585.2.camel@gmail.com>
Date: Mon, 27 Nov 2017 08:42:16 +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 v2] scripts: leaking_addresses: add support for 32-bit
kernel addresses
Currently, leaking_addresses.pl only supports scanning and displaying 'leaked'
64-bit kernel virtual addresses. We can scan for and display 'leaked' 32-bit
kernel virtual addresses as well.
Briefly, the way it works: once it detects we're running on an i'x'86 platform,
(where x=3|4|5|6), it takes this arch into account for checking. The essential
rationale:
if 32-bit-virt-addr >= PAGE_OFFSET => it's a kernel virtual address.
This version programatically queries and sets PAGE_OFFSET based on it's value
in one of these files: /boot/config, /boot/config-$(uname -r) and
/proc/config.gz. If, for any reason, none of these files can be used, we
fallback to requesting the user to pass PAGE_OFFSET as an option switch.
Feedback welcome..
Kaiwan N Billimoria (1):
scripts: leaking_addresses: add support for 32-bit kernel addresses
scripts/leaking_addresses.pl | 150 +++++++++++++++++++++++++++++++++++++------
1 file changed, 132 insertions(+), 18 deletions(-)
Signed-off-by: Kaiwan N Billimoria <kaiwan.billimoria@...il.com>
---
diff --git a/scripts/leaking_addresses.pl b/scripts/leaking_addresses.pl
index 2d5336b3e1ea..fccd0a5094f1 100755
--- a/scripts/leaking_addresses.pl
+++ b/scripts/leaking_addresses.pl
@@ -5,7 +5,7 @@
# 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).
#
@@ -14,7 +14,7 @@
#
# You may like to set kptr_restrict=2 before running script
# (see Documentation/sysctl/kernel.txt).
-
+#
use warnings;
use strict;
use POSIX;
@@ -37,7 +37,7 @@ 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;
@@ -49,6 +49,9 @@ 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.
+my $page_offset_32bit = 0; # 32-bit: value of CONFIG_PAGE_OFFSET
+
+my @kernel_config_files = ('/boot/config', '/boot/config-'.`uname -r`, '/proc/config.gz');
# Do not parse these files (absolute path).
my @skip_parse_files_abs = ('/proc/kmsg',
@@ -97,14 +100,15 @@ 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.
+ -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.
+ --page-offset-32bit=<hex> PAGE_OFFSET value (for 32-bit kernels).
+ -d, --debug Display debugging output.
+ -h, --help, --version Display this help and exit.
Examples:
@@ -117,7 +121,11 @@ Examples:
# View summary report.
$0 --input-raw scan.out --squash-by-filename
-Scans the running (64 bit) kernel for potential leaking addresses.
+ # (On a 32-bit system with a 2GB:2GB VMSPLIT), pass PAGE_OFFSET value
+ # as an option switch.
+ $0 --page-offset-32bit=0x80000000
+
+Scans the running kernel for potential leaking addresses.
EOM
exit($exitcode);
@@ -133,10 +141,16 @@ GetOptions(
'squash-by-path' => \$squash_by_path,
'squash-by-filename' => \$squash_by_filename,
'raw' => \$raw,
+ 'page-offset-32bit=o' => \$page_offset_32bit,
) or help(1);
help(0) if ($help);
+sub dprint
+{
+ printf(STDERR @_) if $debug;
+}
+
if ($input_raw) {
format_output($input_raw);
exit(0);
@@ -162,6 +176,20 @@ if (!is_supported_architecture()) {
exit(129);
}
+if ($debug) {
+ printf "Detected arch : ";
+ if (is_ix86_32()) {
+ printf "32 bit x86\n";
+ } else {
+ printf "64 bit\n";
+ }
+}
+
+if (is_ix86_32()) {
+ $page_offset_32bit = get_page_offset();
+ dprint "PAGE_OFFSET = 0x%X\n", $page_offset_32bit;
+}
+
if ($output_raw) {
open my $fh, '>', $output_raw or die "$0: $output_raw: $!\n";
select $fh;
@@ -172,14 +200,9 @@ walk(@DIRS);
exit 0;
-sub dprint
-{
- printf(STDERR @_) if $debug;
-}
-
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
@@ -202,6 +225,17 @@ sub is_ppc64
return 0;
}
+# 32-bit x86: is_i'x'86_32() ; where is [3 or 4 or 5 or 6]
+sub is_ix86_32
+{
+ my $archname = $Config{archname};
+
+ if ($archname =~ m/i[3456]86-linux/) {
+ return 1;
+ }
+ return 0;
+}
+
sub is_false_positive
{
my ($match) = @_;
@@ -217,6 +251,14 @@ sub is_false_positive
$match =~ '\bf{10}601000\b') {
return 1;
}
+ } elsif (is_ix86_32()) {
+ my $addr32 = eval hex($match);
+ if ($addr32 < $page_offset_32bit ) {
+ return 1;
+ }
+ if ($match =~ '\b(0x)?(f|F){8}\b') {
+ return 1;
+ }
}
return 0;
@@ -245,6 +287,8 @@ sub may_leak_address
$address_re = '\b(0x)?ffff[[:xdigit:]]{12}\b';
} elsif (is_ppc64()) {
$address_re = '\b(0x)?[89abcdef]00[[:xdigit:]]{13}\b';
+ } elsif (is_ix86_32()) {
+ $address_re = '\b(0x)?[[:xdigit:]]{8}\b';
}
while (/($address_re)/g) {
@@ -501,3 +545,73 @@ sub add_to_cache
}
push @{$cache->{$key}}, $value;
}
+
+sub parse_kernel_config
+{
+ my ($file, $config) = @_;
+ my $str;
+ my $val = NULL;
+ my $gzipfile = 0;
+
+ # Explicitly check for '/proc/config.gz'
+ if ($file eq "/proc/config.gz") {
+ $gzipfile = 1;
+ if (! -R $file) {
+ dprint "parse_kernel_config: /proc/config.gz does not exist\n";
+ return NULL;
+ }
+ if (system("gunzip < /proc/config.gz > /tmp/tmpkconf")) {
+ dprint " parse_kernel_config: system(gunzip...) failed\n";
+ return NULL;
+ }
+ $file = "/tmp/tmpkconf";
+ $file =~ s/\R*//g;
+ }
+
+ dprint "32-bit: attempting to parse file \"$file\" for config \"$config\" ...\n";
+ if (! -R $file) {
+ dprint " parse_kernel_config: file does not exist or not readable\n";
+ return NULL;
+ }
+
+ open my $fh, "<", $file or return;
+ while (my $line = <$fh> ) {
+ if ($line =~ /^$config/) {
+ ($str,$val) = split /=/, $line;
+ }
+ }
+ close $fh;
+ if ($gzipfile == 1) {
+ system("rm -f /tmp/tmpkconf");
+ }
+
+ if ($val eq NULL) {
+ return NULL;
+ }
+ $val =~ s/\R*//g;
+ return $val;
+}
+
+sub get_page_offset
+{
+ my $page_offset = $page_offset_32bit;
+
+ # If option --page-offset-32bit has been passed, just use it, else
+ # parse PAGE_OFFSET by iterating over an array of kernel config files.
+ if ($page_offset == 0) {
+ foreach my $kconfig_file (@kernel_config_files) {
+ $kconfig_file =~ s/\R*//g;
+ $page_offset = eval parse_kernel_config($kconfig_file, "CONFIG_PAGE_OFFSET");
+ if ($page_offset != 0) {
+ last;
+ }
+ }
+ if ($page_offset == 0) {
+ printf STDERR "$P: Fatal Error :: couldn't parse CONFIG_PAGE_OFFSET, aborting...\n";
+ printf STDERR "You can pass it via the option switch --page-offset-32bit=<value>\n";
+ exit(1);
+ }
+ }
+ return $page_offset;
+}
+
--
2.14.3
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