1#!/usr/bin/perl -T 2 3# $OpenBSD: security,v 1.43 2024/06/09 18:31:17 afresh1 Exp $ 4# 5# Copyright (c) 2011, 2012, 2014, 2015 Ingo Schwarze <schwarze@openbsd.org> 6# Copyright (c) 2011 Andrew Fresh <andrew@afresh1.com> 7# 8# Permission to use, copy, modify, and distribute this software for any 9# purpose with or without fee is hereby granted, provided that the above 10# copyright notice and this permission notice appear in all copies. 11# 12# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 13# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 14# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 15# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 16# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 17# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 18# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 19 20use warnings; 21use strict; 22 23use Digest::SHA qw(sha256_hex); 24use Errno qw(ENOENT); 25use Fcntl qw(O_RDONLY O_NONBLOCK :mode); 26use File::Basename qw(basename); 27use File::Compare qw(compare); 28use File::Copy qw(copy); 29require File::Find; 30 31use constant { 32 BACKUP_DIR => '/var/backups/', 33 RELINK_DIR => '/usr/share/relink/', 34}; 35 36$ENV{PATH} = '/bin:/usr/bin:/sbin:/usr/sbin'; 37delete $ENV{ENV}; 38umask 077; 39 40my $check_title; 41my $return_code = 0; 42 43sub nag ($$) { 44 my ($cond, $msg) = @_; 45 if ($cond) { 46 if ($check_title) { 47 print "\n$check_title\n"; 48 undef $check_title; 49 } 50 print "$msg\n"; 51 $return_code = 1; 52 } 53 return $cond; 54} 55 56sub close_or_nag { 57 my ($fh, $cmd) = @_; 58 my $res = close $fh; 59 nag !$res, "$cmd: " . 60 ($! ? "error closing pipe: $!" : "exit code " . ($? >> 8)); 61 return $res; 62} 63 64sub check_access_file { 65 my ($filename, $login) = @_; 66 return unless -e $filename; 67 my $mode = (stat(_))[2]; 68 nag $mode & (S_IRUSR | S_IRGRP | S_IROTH) && ! -O $filename, 69 "Login $login is off but still has a valid shell " . 70 "and alternate access files in\n" . 71 "\t home directory are still readable."; 72} 73 74sub check_passwd { 75 my $filename = '/etc/master.passwd'; 76 $check_title = "Checking the $filename file:"; 77 nag !(open my $fh, '<', $filename), "open: $filename: $!" and return; 78 my (%logins, %uids); 79 while (my $line = <$fh>) { 80 chomp $line; 81 nag $line !~ /\S/, 82 "Line $. is a blank line." 83 and next; 84 my @f = split /:/, $line, -1; 85 nag @f != 10, 86 "Line $. has the wrong number of fields:\n$line"; 87 my ($name, $pwd, $uid, $gid, $class, $chg, $exp, $gecos, 88 $home, $shell) = @f; 89 next if $name =~ /^[+-]/; # skip YP lines 90 unless (nag $name eq '', 91 "Line $. has an empty login field:\n$line") { 92 nag $name !~ /^[A-Za-z0-9_][-.A-Za-z0-9_]*\$?$/, 93 "Login $name has non-alphanumeric characters."; 94 nag $logins{$name}++, 95 "Duplicate user name $name."; 96 } 97 nag length $name > 31, 98 "Login $name has more than 31 characters."; 99 nag $pwd eq '' && !($name eq 'anoncvs' && 100 $shell =~ /\/anoncvssh$/), 101 "Login $name has no password."; 102 if ($pwd ne '' && 103 $pwd ne 'skey' && 104 length $pwd != 13 && 105 $pwd !~ /^\$[0-9a-f]+\$/ && 106 ($shell eq '' || $shell =~ /sh$/)) { 107 nag -s "/etc/skey/$name", 108 "Login $name is off but still has a valid " . 109 "shell and an entry in /etc/skey."; 110 nag -d $home && ! -r $home, 111 "Login $name is off but still has valid " . 112 "shell and home directory is unreadable\n" . 113 "\t by root; cannot check for existence " . 114 "of alternate access files." 115 or check_access_file "$home/.$_", $name 116 foreach qw(ssh rhosts shosts); 117 } 118 nag $uid == 0 && $name ne 'root', 119 "Login $name has a user ID of 0."; 120 nag $uid < 0, 121 "Login $name has a negative user ID."; 122 nag $uids{$uid}++, 123 "Login $name has duplicate user ID $uid."; 124 nag $gid < 0, 125 "Login $name has a negative group ID."; 126 nag $exp != 0 && $exp < time, 127 "Login $name has expired."; 128 } 129 close $fh; 130} 131 132# Backup the master password file; a special case, the normal backup 133# mechanisms also print out file differences and we don't want to do 134# that because this file has encrypted passwords in it. 135sub backup_passwd { 136 my $base = 'master.passwd'; 137 my $orig = "/etc/$base"; 138 my $curr = BACKUP_DIR . "$base.current"; 139 if (!-s $curr) { 140 # nothing 141 } elsif (compare $curr, $orig) { 142 copy $curr, BACKUP_DIR . "$base.backup"; 143 } else { 144 return; 145 } 146 copy $orig, $curr; 147 chown 0, 0, $curr; 148} 149 150# Check the group file syntax. 151sub check_group { 152 my $filename = '/etc/group'; 153 $check_title = "Checking the $filename file:"; 154 nag !(open my $fh, '<', $filename), "open: $filename: $!" and return; 155 my (%names, $global_yp); 156 while (my $line = <$fh>) { 157 chomp $line; 158 nag $global_yp, 159 'Global YP inclusion ("+") is not the last line.' 160 and undef $global_yp; 161 if ($line eq '+') { 162 $global_yp = 1; 163 next; 164 } 165 nag $line !~ /\S/, 166 "Line $. is a blank line." 167 and next; 168 my @f = split /:/, $line, -1; 169 nag @f != 4, 170 "Line $. has the wrong number of fields:\n$line"; 171 my ($name, $pwd, $gid, $members) = @f; 172 next if $name =~ /^[+-]/; # skip YP lines 173 unless (nag $name eq '', 174 "Line $. has an empty group name field:\n$line") { 175 nag $name !~ /^[A-Za-z0-9_][-.A-Za-z0-9_]*$/, 176 "Group $name has non-alphanumeric characters."; 177 nag $names{$name}++, 178 "Duplicate group name $name."; 179 } 180 nag length $name > 31, 181 "Group $name has more than 31 characters."; 182 nag $gid =~ /[^\d]/, 183 "Group $name has an invalid group ID."; 184 } 185 close $fh; 186} 187 188sub check_umask { 189 my ($filename) = @_; 190 nag !(open my $fh, '<', $filename), "open: $filename: $!" and return; 191 my $umaskset; 192 while (<$fh>) { 193 next unless /^\s*umask\s+([0-7]+)/; 194 my $umask = "0$1"; 195 $umaskset = 1; 196 my ($other, $group) = reverse split '', $umask; 197 nag $group =~ /^[0145]$/, 198 "Root umask is group writable"; 199 nag $other =~ /^[0145]$/, 200 "Root umask is other writable"; 201 } 202 close $fh; 203 return $umaskset; 204} 205 206# This type of test by spawning a shell is messy and fragile. 207# Instead, consider modifying the shells to warn about '.' in the PATH. 208sub check_root_path { 209 my ($path, $filename) = @_; 210 nag !(defined $path && $path =~ s/^PATH=[:\s]*//), 211 "Failed to find PATH in $filename." 212 and return; 213 foreach my $dir (split /[:\s]+/, $path) { 214 nag $dir eq '.', "The root path includes ." and next; 215 next unless -d $dir; 216 my $mode = (stat(_))[2]; 217 nag $mode & S_IWGRP, 218 "Root path directory $dir is group writable."; 219 nag $mode & S_IWOTH, 220 "Root path directory $dir is other writable."; 221 } 222} 223 224# Check for umask values and root paths in startup files. 225sub check_csh { 226 my @list = qw(/etc/csh.cshrc /etc/csh.login /root/.cshrc /root/.login); 227 $check_title = "Checking root csh paths, umask values:\n@list"; 228 229 my $umaskset = 0; 230 foreach my $filename (@list) { 231 next unless -s $filename; 232 $umaskset = 1 if check_umask $filename; 233 234 nag !(open my $fh, '-|', qw(/bin/csh -f -c), 235 "eval 'source $filename' >& /dev/null; " . 236 "echo PATH=\$path"), 237 "cannot spawn /bin/csh: $!" 238 and next; 239 my @output = <$fh>; 240 close_or_nag $fh, "csh $filename" or next; 241 chomp @output; 242 check_root_path pop @output, $filename; 243 } 244 nag !$umaskset, 245 "\nRoot csh startup files do not set the umask."; 246} 247 248sub check_sh { 249 my @list = qw(/etc/profile /root/.profile); 250 $check_title = "Checking root sh paths, umask values:\n@list"; 251 252 my @env_path; 253 my $umaskset = 0; 254 foreach my $filename (@list) { 255 next unless -s $filename; 256 $umaskset ||= check_umask($filename); 257 258 nag !(open my $fh, '-|', qw(/bin/sh -c), 259 ". $filename; echo ENV=\$ENV; echo PATH=\$PATH"), 260 "cannot spawn /bin/sh: $!" 261 and next; 262 my @output = <$fh>; 263 close_or_nag $fh, "sh $filename" or next; 264 chomp @output; 265 check_root_path pop @output, $filename; 266 267 my $env = pop @output; 268 nag !(defined $env && $env =~ /^ENV=\s*(\S*)/), 269 "Failed to find ENV in $filename." 270 and next; 271 push @env_path, $1 if $1 ne ''; 272 } 273 nag !$umaskset, 274 "\nRoot sh startup files do not set the umask."; 275 return @env_path; 276} 277 278sub check_ksh { 279 my @list = ('/etc/ksh.kshrc', @_); 280 $check_title = "Checking root ksh paths, umask values:\n@list"; 281 282 # Usually, we are at HOME anyway, but for the ENV check, this 283 # is particularly important, so make sure we are really there. 284 chdir '/root'; 285 286 # A good .kshrc will not have a umask or path, 287 # that being set in .profile; check anyway. 288 foreach my $filename (@list) { 289 next unless -s $filename; 290 check_umask($filename); 291 292 nag !(open my $fh, '-|', qw(/bin/ksh -c), 293 ". $filename; echo PATH=\$PATH"), 294 "cannot spawn /bin/ksh: $!" 295 and next; 296 my @output = <$fh>; 297 close_or_nag $fh, "ksh $filename" or next; 298 chomp @output; 299 check_root_path pop @output, $filename; 300 } 301} 302 303# Uudecode should not be in the /etc/mail/aliases file. 304sub check_mail_aliases { 305 my $filename = '/etc/mail/aliases'; 306 nag !(open my $fh, '<', $filename), "open: $filename: $!" and return; 307 no warnings 'uninitialized'; 308 nag /^((?:uu)?decode)/, 309 "There is an entry for $1 in the $filename file." 310 while <$fh>; 311 close $fh; 312} 313 314# hostname.if files may contain secrets and should not be world-readable. 315sub check_hostname_if { 316 while (my $filename = glob '/etc/hostname.*') { 317 next unless -e $filename; 318 my $mode = (stat(_))[2]; 319 nag $mode & S_IRWXO, 320 "$filename is world readable."; 321 } 322} 323 324# hosts.lpd should not have + signs. 325sub check_hosts_lpd { 326 my $filename = '/etc/hosts.lpd'; 327 -s $filename or return; 328 nag !(open my $fh, '<', $filename), "open: $filename: $!" and return; 329 nag /^\+/ && !/^\+@/, 330 "Plus sign in $filename file." 331 while <$fh>; 332 close $fh; 333} 334 335sub find_homes { 336 my $filename = '/etc/passwd'; 337 nag !(open my $fh, '<', $filename), 338 "open: $filename: $!" 339 and return []; 340 my $homes = []; 341 while (<$fh>) { 342 my $entry = [ @{[split /:/]}[0,2,5] ]; 343 chomp; 344 nag !defined $entry->[2], 345 "Incomplete line \"$_\" in $filename." 346 and next; 347 chomp $entry->[2]; 348 push @$homes, $entry; 349 } 350 close $fh; 351 return $homes; 352} 353 354# Check for special users with .rhosts/.shosts files. 355# Only root should have .rhosts/.shosts files. 356sub check_rhosts_owner { 357 my ($name, $uid, $home) = @_; 358 return if $name =~ /^[+-]/; # skip YP lines 359 foreach my $base (qw(rhosts shosts)) { 360 my $filename = "$home/.$base"; 361 next unless -s $filename; 362 nag ! -O $filename && 363 ($name eq 'ftp' || ($uid < 100 && $name ne 'root')), 364 "$filename is not owned by root."; 365 } 366} 367 368# Also, .rhosts/.shosts files should not have plus signs. 369sub check_rhosts_content { 370 my ($name, $uid, $home) = @_; 371 foreach my $base (qw(rhosts shosts)) { 372 my $filename = "$home/.$base"; 373 next unless -s $filename; 374 nag !sysopen(my $fh, $filename, O_RDONLY | O_NONBLOCK), 375 "open: $filename: $!" 376 and next; 377 nag !(-f $fh), 378 "$filename is not a regular file" 379 and next; 380 local $_; 381 nag /^\+\s*$/, 382 "$filename has + sign in it." 383 while <$fh>; 384 close $fh; 385 } 386} 387 388# Home directories should not be owned by someone else or writeable. 389sub check_homedir { 390 my ($name, $uid, $home) = @_; 391 return if $name =~ /^[+-]/; # skip YP lines 392 return unless -d $home; 393 my ($mode, $fuid) = (stat(_))[2,4]; 394 nag $fuid && $fuid != $uid, 395 "user $name home directory is owned by " . 396 ((getpwuid $fuid)[0] // $fuid); 397 nag $mode & S_IWGRP, 398 "user $name home directory is group writable"; 399 nag $mode & S_IWOTH, 400 "user $name home directory is other writable"; 401} 402 403# Files that should not be owned by someone else or readable. 404sub check_dot_readable { 405 my ($name, $uid, $home) = @_; 406 return if $name =~ /^[+-]/; # skip YP lines 407 foreach my $f (qw( 408 .netrc .rhosts .gnupg/secring.gpg .gnupg/random_seed 409 .pgp/secring.pgp .shosts .ssh/identity .ssh/id_dsa .ssh/id_ecdsa 410 .ssh/id_rsa .ssh/id_ed25519 411 )) { 412 next unless -e "$home/$f"; 413 my ($mode, $fuid) = (stat(_))[2,4]; 414 nag $fuid && $fuid != $uid, 415 "user $name $f file is owned by " . 416 ((getpwuid $fuid)[0] // $fuid); 417 nag $mode & S_IRGRP, 418 "user $name $f file is group readable"; 419 nag $mode & S_IROTH, 420 "user $name $f file is other readable"; 421 nag $mode & S_IWGRP, 422 "user $name $f file is group writable"; 423 nag $mode & S_IWOTH, 424 "user $name $f file is other writable"; 425 } 426} 427 428# Files that should not be owned by someone else or writeable. 429sub check_dot_writeable { 430 my ($name, $uid, $home) = @_; 431 return if $name =~ /^[+-]/; # skip YP lines 432 foreach my $f (qw( 433 .bashrc .bash_profile .bash_login .bash_logout .cshrc 434 .emacs .exrc .forward .fvwmrc .inputrc .kshrc .login 435 .logout .nexrc .profile .screenrc .ssh .ssh/config 436 .ssh/authorized_keys .ssh/authorized_keys2 .ssh/environment 437 .ssh/known_hosts .ssh/rc .tcshrc .twmrc .xsession .xinitrc 438 .Xdefaults .Xauthority 439 )) { 440 next unless -e "$home/$f"; 441 my ($mode, $fuid) = (stat(_))[2,4]; 442 nag $fuid && $fuid != $uid, 443 "user $name $f file is owned by " . 444 ((getpwuid $fuid)[0] // $fuid); 445 nag $mode & S_IWGRP, 446 "user $name $f file is group writable"; 447 nag $mode & S_IWOTH, 448 "user $name $f file is other writable"; 449 } 450} 451 452# Mailboxes should be owned by the user and unreadable. 453sub check_mailboxes { 454 my $dir = '/var/mail'; 455 nag !(opendir my $dh, $dir), "opendir: $dir: $!" and return; 456 foreach my $name (readdir $dh) { 457 next if $name =~ /^\.\.?$/; 458 next if $name =~ /.\.lock$/; 459 my ($mode, $fuid, $fgid) = (stat "$dir/$name")[2,4,5]; 460 unless (defined $mode) { 461 nag !$!{ENOENT}, "stat: $dir/$name: $!"; 462 next; 463 } 464 my $fname = (getpwuid $fuid)[0] // $fuid; 465 my $gname = (getgrgid $fgid)[0] // $fgid; 466 nag $fname ne $name, 467 "user $name mailbox is owned by $fname"; 468 nag S_IMODE($mode) != (S_IRUSR | S_IWUSR), 469 sprintf 'user %s mailbox is %s, group %s', 470 $name, strmode($mode), $gname; 471 } 472 closedir $dh; 473} 474 475# File systems should not be globally exported. 476sub check_exports { 477 my $filename = '/etc/exports'; 478 return unless -e $filename; 479 nag !(open my $fh, '<', $filename), "open: $filename: $!" and return; 480 481 LINE: while (<$fh>) { 482 chomp; 483 next if /^(?:#|$)/; 484 485 my @fs; 486 my $readonly = 0; 487 foreach (split) { 488 if (/^\//) { push @fs, $_; } 489 elsif ($_ eq '-ro') { $readonly = 1; } 490 elsif (/^(?:[^-]|-network)/) { next LINE; } 491 } 492 493 nag 1, "File system @fs globally exported, " 494 . ($readonly ? 'read-only.' : 'read-write.'); 495 } 496 close $fh; 497} 498 499sub strmode_x { 500 my ($mode, $x, $s) = @_; 501 $x &= $mode; 502 $s &= $mode; 503 return ($x && $s) ? 's' : $x ? 'x' : $s ? 'S' : '-'; 504} 505 506sub strmode { 507 my ($mode) = @_; 508 509 my %types = ( 510 S_IFDIR, 'd', # directory 511 S_IFCHR, 'c', # character special 512 S_IFBLK, 'b', # block special 513 S_IFREG, '-', # regular 514 S_IFLNK, 'l', # symbolic link 515 S_IFSOCK, 's', # socket 516 S_IFIFO, 'p', # fifo 517 ); 518 519 return 520 ($types{ $mode & S_IFMT } || '?') 521 . (($mode & S_IRUSR) ? 'r' : '-') 522 . (($mode & S_IWUSR) ? 'w' : '-') 523 . (strmode_x $mode, S_IXUSR, S_ISUID) 524 . (($mode & S_IRGRP) ? 'r' : '-') 525 . (($mode & S_IWGRP) ? 'w' : '-') 526 . (strmode_x $mode, S_IXGRP, S_ISGID) 527 . (($mode & S_IROTH) ? 'r' : '-') 528 . (($mode & S_IWOTH) ? 'w' : '-') 529 . (strmode_x $mode, S_IXOTH, S_ISVTX); 530} 531 532sub find_special_files { 533 my (%skip, @fs); 534 535 %skip = map { $_ => 1 } split ' ', $ENV{SUIDSKIP} 536 if $ENV{SUIDSKIP}; 537 538 # Add mount points of non-local file systems 539 # to the list of directories to skip. 540 nag !(open my $fh, '-|', 'mount'), 541 "cannot spawn mount: $!" 542 and return; 543 while (<$fh>) { 544 my ($path, $opt) = /\son\s+(.*?)\s+type\s+\w+(.*)/; 545 push @fs, $path if $path && $opt =~ /local/ && 546 !($opt =~ /nodev/ && $opt =~ /nosuid/); 547 } 548 close_or_nag $fh, "mount" or return; 549 return unless @fs; 550 551 my $setuid_files = {}; 552 my $device_files = {}; 553 my $uudecode_is_setuid = 0; 554 555 File::Find::find({no_chdir => 1, wanted => sub { 556 557 if ($skip{$_}) { 558 $File::Find::prune = 1; 559 return; 560 } 561 562 my ($dev, $ino, $mode, $nlink, $uid, $gid, $rdev, $size, 563 $atime, $mtime, $ctime, $blksize, $blocks) = lstat; 564 if (defined $dev) { 565 no warnings 'once'; 566 if ($dev != $File::Find::topdev) { 567 $File::Find::prune = 1; 568 return; 569 } 570 } else { 571 nag !$!{ENOENT}, "stat: $_: $!"; 572 return; 573 } 574 575 # SUID/SGID files 576 my $file = {}; 577 if (-f _ && $mode & (S_ISUID | S_ISGID)) { 578 return if -e RELINK_DIR . $_; 579 $setuid_files->{$File::Find::name} = $file; 580 $uudecode_is_setuid = 1 581 if basename($_) eq 'uudecode'; 582 } 583 584 # Special Files 585 elsif (!-d _ && !-f _ && !-l _ && !-S _ && !-p _ ) { 586 $device_files->{$File::Find::name} = $file; 587 $file->{major} = (($rdev >> 8) & 0xff) . ','; 588 $file->{minor} = (($rdev >> 8) & 0xffff00) | 589 ($rdev & 0xff); 590 } else { 591 return; 592 } 593 594 $file->{mode} = $mode; 595 $file->{strmode} = strmode $mode; 596 $file->{nlink} = $nlink; 597 $file->{user} = (getpwuid $uid)[0] // $uid; 598 $file->{group} = (getgrgid $gid)[0] // $gid; 599 $file->{size} = $size; 600 @$file{qw(wday mon day time year)} = 601 split ' ', localtime $mtime; 602 }}, @fs); 603 604 nag $uudecode_is_setuid, 'Uudecode is setuid.'; 605 return $setuid_files, $device_files; 606} 607 608sub adjust_columns { 609 my (@table) = @_; 610 611 my @s; 612 foreach my $row (@table) { 613 for (0 .. $#$row) { 614 $s[$_] = length $row->[$_] 615 if (!$s[$_] || length $row->[$_] > $s[$_]); 616 } 617 } 618 $s[-1] = '0'; 619 my $fmt = join ' ', map { m/(\d+)/ && "%-$1s"} @s; 620 621 return map { sprintf $fmt, @$_ } @table; 622} 623 624# Display any changes in setuid/setgid files and devices. 625sub check_filelist { 626 my ($files, $mode) = @_; 627 my $current = BACKUP_DIR . "$mode.current"; 628 my $backup = BACKUP_DIR . "$mode.backup"; 629 my @fields = ( 630 qw(strmode nlink user group), 631 $mode eq 'device' ? qw(major minor) : 'size', 632 qw(mon day time year) 633 ); 634 635 my %current; 636 if (-s $current) { 637 nag !(open my $fh, '<', $current), "open: $current: $!" 638 and return; 639 while (<$fh>) { 640 chomp; 641 my (%f, $file); 642 (@f{@fields}, $file) = split ' ', $_, @fields + 1; 643 $current{$file} = \%f; 644 } 645 close $fh; 646 } 647 648 my %changed; 649 foreach my $f (sort keys %$files) { 650 if (my $old = delete $current{$f}) { 651 next if $mode eq 'device' && 652 !S_ISBLK($files->{$f}{mode}); 653 foreach my $k (@fields) { 654 next if $old->{$k} eq $files->{$f}{$k}; 655 push @{$changed{changes}}, 656 [ @$old{@fields}, $f ], 657 [ @{$files->{$f}}{@fields}, $f ]; 658 last; 659 } 660 next; 661 } 662 push @{$changed{additions}}, [ @{$files->{$f}}{@fields}, $f ]; 663 } 664 foreach my $f (sort keys %current) { 665 next if $mode eq 'setuid' && -e RELINK_DIR . $f; 666 push @{$changed{deletions}}, [ @{$current{$f}}{@fields}, $f ]; 667 }; 668 669 foreach my $k (qw( additions deletions changes )) { 670 next unless exists $changed{$k}; 671 $mode = 'block device' if $mode eq 'device' && $k eq 'changes'; 672 $check_title = (ucfirst $mode) . " $k:"; 673 nag 1, $_ for adjust_columns @{$changed{$k}}; 674 } 675 676 return if !%changed; 677 copy $current, $backup; 678 679 nag !(open my $fh, '>', $current), "open: $current: $!" and return; 680 print $fh "@{$files->{$_}}{@fields} $_\n" foreach sort keys %$files; 681 close $fh; 682} 683 684# Check for block and character disk devices that are readable or writeable 685# or not owned by root.operator. 686sub check_disks { 687 my ($files) = @_; 688 689 my $disk_re = qr/ 690 \/ 691 (?:ccd|dk|fd|hd|hk|hp|jb|kra|ra|rb|rd|rl|rx|rz|sd|up|vnd|wd|xd) 692 \d+ [B-H]? [a-p] 693 $ 694 /x; 695 696 foreach my $file (sort keys %$files) { 697 next if $file !~ /$disk_re/; 698 my $f = $files->{$file}; 699 nag $f->{user} ne 'root' || $f->{group} ne 'operator' || 700 S_IMODE($f->{mode}) != (S_IRUSR | S_IWUSR | S_IRGRP), 701 sprintf("Disk %s is user %s, group %s, permissions %s.", 702 $file, $f->{user}, $f->{group}, $f->{strmode}); 703 } 704} 705 706# Check special files and system binaries. 707# 708# Create the mtree tree specifications using: 709# 710# mtree -cx -p DIR -K sha256digest,type > /etc/mtree/DIR.secure 711# chown root:wheel /etc/mtree/DIR.secure 712# chmod 600 /etc/mtree/DIR.secure 713# 714# Note, this is not complete protection against Trojan horsed binaries, as 715# the hacker can modify the tree specification to match the replaced binary. 716# For details on really protecting yourself against modified binaries, see 717# the mtree(8) manual page. 718sub check_mtree { 719 nag !-d '/etc/mtree', '/etc/mtree is missing' and return; 720 721 if (open my $fh, '-|', qw(mtree -e -l -p / -f /etc/mtree/special)) { 722 nag 1, $_ for map { chomp; $_ } <$fh>; 723 close_or_nag $fh, "mtree special"; 724 } else { nag 1, "cannot spawn mtree: $!"; } 725 726 while (my $filename = glob '/etc/mtree/*.secure') { 727 nag !(open my $fh, '<', $filename), 728 "open: $filename: $!" 729 and next; 730 731 my $tree; 732 while (<$fh>) { 733 last unless /^#/; 734 ($tree) = /^#\s+tree:\s+(.*)/ and last; 735 } 736 next unless $tree; 737 738 $check_title = "Checking system binaries in $tree:"; 739 nag !(open $fh, '-|', 'mtree', '-f', $filename, '-p', $tree), 740 "cannot spawn mtree: $!" 741 and next; 742 nag 1, $_ for map { chomp; $_ } <$fh>; 743 close_or_nag $fh, "mtree $filename"; 744 } 745} 746 747sub diff { 748 nag !(open my $fh, '-|', qw(diff -ua), @_), 749 "cannot spawn diff: $!" 750 and return; 751 local $/; 752 my $diff = <$fh>; 753 { 754 close $fh and last; 755 nag $!, "diff: error closing pipe: $!" and last; 756 nag $? >> 8 > 1, "diff: exit code " . ($? >> 8); 757 } 758 return nag !!$diff, $diff; 759} 760 761sub backup_if_changed { 762 my ($orig) = @_; 763 764 my ($backup) = $orig =~ /(.*)/; 765 if (index $backup, BACKUP_DIR) { 766 $backup =~ s{^/}{}; 767 $backup =~ s{/}{_}g; 768 $backup = BACKUP_DIR . $backup; 769 } 770 my $current = "$backup.current"; 771 $backup .= '.backup'; 772 my $last = -s $current ? $current : '/dev/null'; 773 $orig = '/dev/null' unless -s $orig; 774 775 diff $last, $orig or return; 776 777 if (-s $current) { 778 copy $current, $backup; 779 chown 0, 0, $backup; 780 } 781 if ($orig eq '/dev/null') { 782 unlink $current; 783 } else { 784 copy $orig, $current; 785 chown 0, 0, $current; 786 } 787} 788 789sub backup_digest { 790 my ($orig) = @_; 791 792 my ($backup) = $orig =~ m{^/?(.*)}; 793 $backup =~ s{/}{_}g; 794 my $current = BACKUP_DIR . "$backup.current.sha256"; 795 $backup = BACKUP_DIR . "$backup.backup.sha256"; 796 797 my $digest_new = 0; 798 if (-s $orig) { 799 if (open my $fh, '<', $orig) { 800 binmode $fh; 801 local $/; 802 $digest_new = sha256_hex(<$fh>); 803 close $fh; 804 } else { nag 1, "open: $orig: $!"; } 805 } 806 807 my $digest_old = 0; 808 if (-s $current) { 809 if (open my $fh, '<', $current) { 810 $digest_old = <$fh>; 811 close $fh; 812 chomp $digest_old; 813 } else { nag 1, "open: $current: $!"; } 814 } 815 816 return if $digest_old eq $digest_new; 817 818 if ($digest_old && $digest_new) { 819 copy $current, $backup; 820 chown 0, 0, $backup; 821 chmod 0600, $backup; 822 } elsif ($digest_old) { 823 $check_title = "======\n$orig removed SHA-256 checksum\n======"; 824 unlink $current; 825 } elsif ($digest_new) { 826 $check_title = "======\n$orig new SHA-256 checksum\n======"; 827 } 828 829 if ($digest_new) { 830 if (open my $fh, '>', $current) { 831 print $fh "$digest_new\n"; 832 close $fh; 833 } else { nag 1, "open: $current: $!\n"; } 834 chown 0, 0, $current; 835 chmod 0600, $current; 836 } 837 838 nag $digest_old, "OLD: $digest_old"; 839 nag $digest_new, "NEW: $digest_new"; 840} 841 842# List of files that get backed up and checked for any modifications. Each 843# file is expected to have two backups, /var/backups/file.{current,backup}. 844# Any changes cause the files to rotate. 845sub check_changelist { 846 my $filename = '/etc/changelist'; 847 -s $filename or return; 848 nag !(open my $fh, '<', $filename), "open: $filename: $!" and return; 849 850 my @relative; 851 while (<$fh>) { 852 next if /^(?:#|\s*$)/; 853 chomp; 854 my $plus = s/^\+//; 855 unless (/^\//) { 856 push @relative, $_; 857 next; 858 } 859 my $tilda = /~$/; 860 861 foreach (glob) { 862 next if $_ eq '/etc/master.passwd'; 863 next if /~$/ && !$tilda; 864 next if -d $_; 865 866 if ($plus) { 867 $check_title = 868 "======\n$_ SHA-256 checksums\n======"; 869 backup_digest $_; 870 } else { 871 $check_title = 872 "======\n$_ diffs (-OLD +NEW)\n======"; 873 backup_if_changed $_; 874 } 875 } 876 } 877 close $fh; 878 879 $check_title = "Skipped relative paths in changelist(5):"; 880 nag 1, $_ foreach @relative; 881} 882 883# Make backups of the labels for any mounted disks 884# and produce diffs when they change. 885sub check_disklabels { 886 nag !(open my $fh, '-|', qw(df -ln)), 887 "cannot spawn df: $!" 888 and return; 889 my %disks; 890 @disks{map m{^/dev/(\w*\d*)[a-p]}, <$fh>} = (); 891 close_or_nag $fh, "df"; 892 893 unless (nag !(open my $fh, '-|', qw(bioctl softraid0)), 894 "cannot spawn bioctl: $!") { 895 @disks{map m{<(\w*\d*)[a-p]>}, <$fh>} = (); 896 close_or_nag $fh, "bioctl"; 897 } 898 899 foreach my $disk (sort keys %disks) { 900 $check_title = "======\n$disk diffs (-OLD +NEW)\n======"; 901 my $filename = BACKUP_DIR . "disklabel.$disk"; 902 system "disklabel $disk > $filename"; 903 backup_if_changed $filename; 904 unlink $filename; 905 } 906} 907 908# Backup the list of installed packages and produce diffs when it changes. 909sub check_pkglist { 910 $check_title = "======\nPackage list changes (-OLD +NEW)\n======"; 911 my $filename = BACKUP_DIR . 'pkglist'; 912 system "pkg_info > $filename 2>&1"; 913 backup_if_changed $filename; 914 unlink $filename; 915} 916 917# main program 918check_passwd; 919backup_passwd; 920check_group; 921check_csh; 922check_ksh(check_sh); 923$check_title = "Checking configuration files:"; 924check_mail_aliases; 925check_hostname_if; 926check_hosts_lpd; 927$check_title = "Checking for special users with .rhosts/.shosts files."; 928my $homes = find_homes; 929check_rhosts_owner @$_ foreach @$homes; 930$check_title = "Checking .rhosts/.shosts files syntax."; 931check_rhosts_content @$_ foreach @$homes; 932$check_title = "Checking home directories."; 933check_homedir @$_ foreach @$homes; 934$check_title = "Checking dot files."; 935check_dot_readable @$_ foreach @$homes; 936check_dot_writeable @$_ foreach @$homes; 937$check_title = "Checking mailbox ownership."; 938check_mailboxes; 939$check_title = "Checking for globally exported file systems."; 940check_exports; 941$check_title = "Setuid/device find errors:"; 942my ($setuid_files, $device_files) = find_special_files; 943$check_title = "Checking setuid/setgid files and devices:"; 944check_filelist $setuid_files, 'setuid' if $setuid_files; 945$check_title = "Checking disk ownership and permissions."; 946check_disks $device_files; 947check_filelist $device_files, 'device' if $device_files; 948$check_title = "Checking special files and directories.\n" . 949 "Output format is:\n\tfilename:\n\t\tcriteria (shouldbe, reallyis)"; 950check_mtree; 951$check_title = "Backing up and comparing configuration files."; 952check_changelist; 953$check_title = "Checking disklabels of mounted disks:"; 954check_disklabels; 955check_pkglist; 956exit $return_code; 957