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Subject[PATCH 1/2] scripts: leaking_addresses: add support for 32-bit kernel addresses
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The current leaking_addresses.pl script only supports showing "leaked"
64-bit kernel virtual addresses. This patch adds support for showing
"leaked" 32-bit kernel virtual addresses. It also takes into account Tobin's
feedback on the previous iteration. (Note: this patch is meant to apply on
the 'leaks' branch of Tobin's tree).

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 virt-addr >= PAGE_OFFSET => it's a kernel virtual address.

This version programatically queries and sets PAGE_OFFSET based on the
/boot/config-$(uname -r) content. If, for any reason, this file cannot be
used, we fallback to requesting the user to pass PAGE_OFFSET as a parameter.

Pending/TODO:
- support for ARM-32

Feedback welcome..


Signed-off-by: Kaiwan N Billimoria <kaiwan.billimoria@gmail.com>
---
diff --git a/scripts/leaking_addresses.pl b/scripts/leaking_addresses.pl
index 865c07649dff..0566f8055ec5 100755
--- a/scripts/leaking_addresses.pl
+++ b/scripts/leaking_addresses.pl
@@ -2,10 +2,10 @@
#
# (c) 2017 Tobin C. Harding <me@tobin.cc>
# (c) 2017 Kaiwan N Billimoria <kaiwan.billimoria@gmail.com> (ix86 support)
-
+
# 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 32/64 bit 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 +49,12 @@ 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_param = 0; # 32-bit: overrides value of PAGE_OFFSET_32BIT
+
+my $bit_size = 64; # Check 64-bit kernel addresses by default
+my $kconfig_file = '/boot/config-'.`uname -r`;
+$kconfig_file =~ s/\R*//g;
+my $PAGE_OFFSET_32BIT = 0xc0000000;

# Do not parse these files (absolute path).
my @skip_parse_files_abs = ('/proc/kmsg',
@@ -99,10 +105,11 @@ 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.
+ --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=<hex> PAGE_OFFSET value (for 32-bit kernels).
-d, --debug Display debugging output.
-h, --help, --version Display this help and exit.

@@ -117,7 +124,7 @@ Examples:
# View summary report.
$0 --input-raw scan.out --squash-by-filename

-Scans the running (64 bit) kernel for potential leaking addresses.
+Scans the running (32 or 64 bit) kernel for potential leaking addresses.

EOM
exit($exitcode);
@@ -133,10 +140,16 @@ GetOptions(
'squash-by-path' => \$squash_by_path,
'squash-by-filename' => \$squash_by_filename,
'raw' => \$raw,
+ 'page-offset=o' => \$page_offset_param,
) or help(1);

help(0) if ($help);

+sub dprint
+{
+ printf(STDERR @_) if $debug;
+}
+
if ($input_raw) {
format_output($input_raw);
exit(0);
@@ -162,6 +175,24 @@ if (!is_supported_architecture()) {
exit(129);
}

+dprint "Detected arch : $bit_size bits\n";
+
+if ($bit_size == 32) {
+ # Parameter --page-offset passed? if Y, override with it
+ if ($page_offset_param != 0) {
+ $PAGE_OFFSET_32BIT = $page_offset_param;
+ } else {
+ $PAGE_OFFSET_32BIT = eval parse_kconfig($kconfig_file, "CONFIG_PAGE_OFFSET");
+ if ($PAGE_OFFSET_32BIT == 0) {
+ printf "$P: Fatal Error :: couldn't parse CONFIG_PAGE_OFFSET, aborting...\n";
+ printf " [Detail :: arch=32-bit, kconfig file=$kconfig_file]\n\n";
+ printf "You can pass it as a parameter via the --page-offset= option switch.\n";
+ exit(1);
+ }
+ }
+ 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 +203,9 @@ 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
@@ -187,6 +213,7 @@ sub is_x86_64
my $archname = $Config{archname};

if ($archname =~ m/x86_64/) {
+ $bit_size = 64;
return 1;
}
return 0;
@@ -197,6 +224,19 @@ sub is_ppc64
my $archname = $Config{archname};

if ($archname =~ m/powerpc/ and $archname =~ m/64/) {
+ $bit_size = 64;
+ return 1;
+ }
+ 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/) {
+ $bit_size = 32;
return 1;
}
return 0;
@@ -217,6 +257,14 @@ sub is_false_positive
$match =~ '\bf{10}601000\b') {
return 1;
}
+ } elsif ($bit_size == 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 +293,8 @@ 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 (/($address_re)/g) {
@@ -501,3 +551,28 @@ sub add_to_cache
}
push @{$cache->{$key}}, $value;
}
+
+sub parse_kconfig
+{
+ my ($file,$config) = @_;
+ my $str;
+ my $val=NULL;
+
+ if (! -R $file) {
+ return NULL;
+ }
+
+ open my $fh, "<", $file or return;
+ while (my $line = <$fh> ) {
+ if ($line =~ /^$config/) {
+ ($str,$val) = split /=/, $line;
+ }
+ }
+ close $fh;
+
+ if ($val eq NULL) {
+ return NULL;
+ }
+ $val =~ s/\R*//g;
+ return $val;
+}
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