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#!/usr/local/cpanel/3rdparty/bin/perl
# cpanel - scripts/shrink_modsec_ip_database Copyright 2022 cPanel, L.L.C.
# All rights reserved.
# copyright@cpanel.net http://cpanel.net
# This code is subject to the cPanel license. Unauthorized copying is prohibited
package scripts::shrink_modsec_ip_database;
use strict;
use warnings;
use File::Temp ();
use Cpanel::PwCache ();
use Cpanel::FileUtils::Move ();
use Cpanel::SafetyBits ();
use Cpanel::SafetyBits::Chown ();
use Cpanel::AccessIds ();
use Cpanel::SafeRun::Object ();
use Cpanel::Imports;
our $MODSEC_SDBM_UTIL = '/usr/sbin/modsec-sdbm-util';
our $DEFAULT_SECDATADIR = '/var/cpanel/secdatadir';
our @DB_FILE_SUFFIXES = qw( .pag .dir ); # Database file suffixes used by modsec-sdbm-util
our $NEW_DB_NAME = 'new_db'; # This name is hard-coded in modsec-sdbm-util
our $DB_PERMS = 0640; # S_IRUSR | S_IWUSR | S_IRGRP
our $OTHER_EXECUTE_PERMS = 01; # S_IXOTH
sub new {
my ( $pkg, $opts ) = @_;
my $self = ref($opts) eq 'HASH' ? { %{$opts} } : {};
bless $self, $pkg;
return $self;
}
sub as_script {
my $self = shift;
logger->die('as_script() is a method call.') unless ref $self eq __PACKAGE__;
if ( not $ARGV[0] or $ARGV[0] ne '-x' ) {
my $msg = 'To execute, use the -x flag.';
logger()->die($msg);
}
$self->run();
return 1;
}
sub run {
my $self = shift;
logger->die('run() is a method call.') unless ref $self eq __PACKAGE__;
return 0 unless $self->_bin_check; # Bail out early and silently if the util is not installed
my $databases = $self->_gather_databases();
while ( my ( $db_path, $uid ) = each %{$databases} ) {
if ( ( stat($MODSEC_SDBM_UTIL) )[2] & $OTHER_EXECUTE_PERMS ) { # Can run util as "other" user?
$self->_shrink_db_as_user( $uid, $db_path );
}
else {
# Will have to settle for doing this as root.
$self->_shrink_db( $uid, $db_path );
}
}
return;
}
sub _bin_check {
return -x $MODSEC_SDBM_UTIL ? 1 : 0;
}
sub _gather_databases {
# All files that belong to the same database and that match @DB_FILE_SUFFIXES will need to have the same file owner or that database will not be in the final output
my $self = shift;
logger->die('_gather_databases() is a method call.') unless ref $self eq __PACKAGE__;
return $self->{'databases'} if defined $self->{'databases'};
my $secdatadir = $self->_secdatadir();
my %databases;
if ( opendir( my $dir_fh, $secdatadir ) ) {
FILE: while ( my $filename = readdir($dir_fh) ) {
SUFFIX: for my $suffix (@DB_FILE_SUFFIXES) {
if ( $filename =~ m{ \A (.*) \Q$suffix\E \Z }xms ) {
my $short_name = $1; # Filename without suffix
my $db_path = $secdatadir . '/' . $short_name; # Database path name suitable for passing to modsec-sdbm-util
next FILE if exists $databases{$db_path}; # Move along if this belongs to a database already in the collection
my $owner = $self->_validate_database_files_owner($db_path); # Check if there is a full set of files for this database path
if ( $self->_allowed_owner($owner) ) {
$databases{$db_path} = $owner; # Verified, add it to the collection
next FILE;
}
}
}
}
closedir($dir_fh);
}
return $self->{'databases'} = \%databases;
}
sub _shrink_db_as_user {
my ( $self, $uid, $db_path ) = @_;
logger->die('_shrink_db_as_user() is a method call.') unless ref $self eq __PACKAGE__;
logger->die('_shrink_db_as_user() called without expected arguments.') unless length $uid && length $db_path;
return Cpanel::AccessIds::do_as_user( $uid, sub { $self->_shrink_db( $uid, $db_path ) } );
}
sub _shrink_db {
my ( $self, $uid, $db_path ) = @_;
logger->die('_shrink_db() is a method call.') unless ref $self eq __PACKAGE__;
logger->die('_shrink_db() called without expected arguments.') unless length $uid && length $db_path;
my $secdatadir = $self->_secdatadir();
my $workdir = File::Temp->newdir( CLEANUP => 1, TEMPLATE => 'shrink_modsec_db_XXXXXXXX', DIR => $secdatadir );
Cpanel::SafetyBits::Chown::safe_chown_guess_gid( $uid, $workdir ) or logger->warn("Failed to chown $workdir to uid $uid");
my @original_files = $self->_get_db_files($db_path);
# modsec-sdbm-util will drop $NEW_DB_NAME * @DB_FILE_SUFFIXES files into $tempdir
return 0 unless $self->_call_modsec_sdbm_util( $workdir, $db_path );
# Verify new files exist and adjust perms
my $new_db_path = $workdir . '/' . $NEW_DB_NAME;
my @new_files = map { $new_db_path . $_ } @DB_FILE_SUFFIXES;
if ( !defined $self->_validate_database_files_owner($new_db_path) ) { # root owned files = 0
logger->warn("Failed to verify the database files generated by modsec-sdbm-util in the working directory");
return 0;
}
$self->_set_default_perms( $uid, \@new_files );
# Move the existing files to the workdir so we can revert if the new-file move fails
my @revert_files = map { $workdir . '/original' . $_ } @DB_FILE_SUFFIXES;
my $can_revert = $self->_move_files( \@original_files, \@revert_files ) or logger->warn("Failed to move original files for $db_path into working dir");
# Move new files into place
if ( !$self->_move_files( \@new_files, \@original_files ) ) {
logger->warn("Failed to move new files into place for $db_path");
if ($can_revert) {
$self->_move_files( \@revert_files, \@original_files ) or logger->warn("Failed to move backup files for $db_path from working dir to original location");
$self->_set_default_perms( $uid, \@original_files );
}
else {
logger->warn("Not able to restore original files for db_path");
}
return 0;
}
# Fix up final database permissions
return 0 unless $self->_set_default_perms( $uid, \@original_files );
return 1;
}
sub _call_modsec_sdbm_util {
my ( $self, $tempdir, $db_path ) = @_;
logger->die('_call_modsec_sdbm_util() is a method call.') unless ref $self eq __PACKAGE__;
logger->die('_call_modsec_sdbm_util() called without expected arguments.') unless length $tempdir && length $db_path;
my $run = Cpanel::SafeRun::Object->new(
program => $MODSEC_SDBM_UTIL,
args => [ '-D', $tempdir, '-v', '-n', $db_path ],
);
# For whatever reason, if the util fails to open the specified db it doesn't exit with an error code, so parse out the error message.
# It will fail to open if the file is immutable -- which is a crazy thing to do on purpose -- but it doesn't make that obvious.
if ( $run->stdout() =~ m{ ^ Failed \s to \s open \s sdbm: \s (.*) $ }xms ) {
logger()->warn("$MODSEC_SDBM_UTIL failed to open database (try checking all file/dir attributes): $1");
return 0;
}
if ( $run->CHILD_ERROR() ) {
logger()->warn( "$MODSEC_SDBM_UTIL exited with non-zero status: " . join( q{ }, map { $run->$_() // () } qw( autopsy stdout stderr ) ) );
return 0;
}
return 1;
}
sub _validate_database_files_owner {
# Expects a database path such as "$secdatadir/$db_name" without a suffix
# Returns owner (uid) of a full set of database files if they exist, undef otherwise
# Remember that root has uid 0!
my ( $self, $db_path ) = @_;
logger->die('_validate_database_files_owner() is a method call.') unless ref $self eq __PACKAGE__;
logger->die('_validate_database_files_owner() called without expected arguments.') unless length $db_path;
my $owner;
for my $file ( $self->_get_db_files($db_path) ) {
return unless -f $file; # All generated filenames must exist
my $seen = ( stat(_) )[4];
$owner //= $seen; # Record owner of the first file we see
return unless $owner == $seen; # Validation fails if any file doesn't match recorded owner
}
return $owner;
}
sub _move_files {
# Move a new set of files in place. The indexes of the source and dest lists of files are expected to correlate directly for the rename.
# For example, $source_files->[0] will be renamed to $dest_files->[0].
my ( $self, $source_files, $dest_files ) = @_;
logger->die('_move_files() is a method call.') unless ref $self eq __PACKAGE__;
logger->die('_move_files() called without expected arguments.') unless ref($source_files) eq 'ARRAY' && ref($dest_files) eq 'ARRAY';
logger->die('_move_files() called without file lists of equal count.') unless scalar @$source_files == scalar @$dest_files;
unlink @$dest_files; # Though they would be overwritten by safemv, there's less chance for a mixture of old and new files if we remove all now and then something goes wrong later
my $result = 1;
while ( my ( $index, $source_file ) = each @$source_files ) {
my $dest_file = $dest_files->[$index];
if ( !Cpanel::FileUtils::Move::safemv( '-f', $source_file, $dest_file ) ) {
logger->warn("Failed to move $source_file to $dest_file");
$result = 0; # Overall fail if any file doesn't move
}
}
return $result;
}
sub _set_default_perms {
my ( $self, $uid, $files ) = @_;
logger->die('_set_default_perms() is a method call.') unless ref $self eq __PACKAGE__;
logger->die('_set_default_perms() called without expected arguments.') unless length $uid && ref($files) eq 'ARRAY' && scalar @$files;
for my $file (@$files) {
if ( !-f $file ) {
logger->warn("Missing expected file $file while trying to update permissions");
return 0; # Must bail out if all of the expected files don't exist.
}
Cpanel::SafetyBits::safe_chmod( $DB_PERMS, $uid, $file ) or logger->warn("Failed to chmod $file");
Cpanel::SafetyBits::Chown::safe_chown_guess_gid( $uid, $file ) or logger->warn("Failed to chown $file to uid $uid");
}
return 1;
}
sub _get_db_files {
# Expects a database path (i.e. "$secdatadir/$shortname") without a suffix
# Generates list of files with known suffixes appended to database path (does not verify existence)
my ( $self, $path ) = @_;
logger->die('_get_db_files() is a method call.') unless ref $self eq __PACKAGE__;
logger->die('_get_db_files() called without expected arguments.') unless length $path;
return map { $path . $_ } @DB_FILE_SUFFIXES;
}
sub _allowed_owner {
# If this is expanded to allow any user, ensure that $owner and its gid exists in Cpanel::PwCache to avoid death by Cpanel::SafetyBits::Chown::safe_chown_guess_gid
my ( $self, $owner ) = @_;
logger->die('_allowed_owner() is a method call.') unless ref $self eq __PACKAGE__;
# undef $owner is not an implementation error here, it simply means the owner couldn't be determined or is intentionally being skipped.
return unless defined $owner;
my $nobody_uid = $self->{'nobody_uid'} //= ( Cpanel::PwCache::getpwnam('nobody') )[2];
return unless defined $nobody_uid;
return 1 if $owner == $nobody_uid;
return 0;
}
sub _secdatadir {
my $self = shift;
logger->die('_secdatadir() is a method call.') unless ref $self eq __PACKAGE__;
$self->{'secdatadir'} //= $DEFAULT_SECDATADIR;
logger->die('Unable to determine secdatadir.') unless length $self->{'secdatadir'};
return $self->{'secdatadir'};
}
if ( not caller() ) {
my $shrink = scripts::shrink_modsec_ip_database->new();
$shrink->as_script;
exit 0;
}
1;
__END__
=head1 NAME
/scripts/shrink_modsec_ip_database
=head1 USAGE AS A SCRIPT
/scripts/shrink_modsec_ip_database -x
=head2 AS A LIBRARY
This script is internally written as a modulino, which means it can be C<require>'d:
use strict;
require q{/scripts/shrink_modsec_ip_database};
my $shrink = scripts::shrink_modsec_ip_database->new();
$shrink->run();
=head1 REQUIRED ARGUMENTS
None
=head1 OPTIONS
=over 4
=item -x
Use this option to actually run the script, otherwise it will warn and return
without doing anything.
=back
=head1 DESCRIPTION
This script is called by C<scripts/maintenance>, and its purpose is to shrink
ModSecurity database files by removing expired entries.
=head1 DIAGNOSTICS
None
=head1 EXIT STATUS
Exit status is 0 (success) unless an unexpected error occurs.
=head1 DEPENDENCIES
This script relies on C</usr/sbin/modsec-sdbm-util> to be installed, and in order to be useful,
C<ModSecurity> must be installed and be enabled.
=head1 INCOMPATIBILITIES
None
=head1 BUGS AND LIMITATIONS
None
=head1 LICENSE AND COPYRIGHT
Copyright 2022 cPanel, L.L.C.