mdw@git.distorted.org.uk Git - misc/blob - shadowfix.in

   1 #! @PERL@
   2 #
   3 # Sanitise Linux password and group databases
   4 #
   5 # (c) 1998 Mark Wooding
   6 #
   7
   8 use MdwOpt;
   9 use FileHandle;
  10 use POSIX;
  11
  12 #----- Documentation --------------------------------------------------------
  13
  14 =head1 NAME
  15
  16 shadowfix - fix password and group files
  17
  18 =head1 SYNOPSIS
  19
  20 B<shadowfix> I<options>...
  21
  22 =head1 DESCRIPTION
  23
  24 Shadowfix trundles through your various password files and makes sure
  25 that they're consistent with themselves.
  26
  27 Currently, the checks Shadowfix makes, and their resolutions, are:
  28
  29 =over 4
  30
  31 =item *
  32
  33 Every user named in the password file should have a shadow password entry;
  34 create a shadow password entry if necessary.
  35
  36 =item *
  37
  38 Every password field in the password file indicates only presence or absence
  39 of a password; move a realistic-looking password to the shadow password file,
  40 and ensure that the password entry in the password file is either empty
  41 (signifying no password) or an `x' character (signifying a password).
  42
  43 =item *
  44
  45 The primary group of each user exists; warn about nonexistent primary groups.
  46
  47 =item *
  48
  49 Every user is a member of his primary group; add the user to the membership
  50 list of the group where necessary.
  51
  52 =item *
  53
  54 There are no entries in the shadow password file which don't match entries in
  55 the main password file; delete orphaned shadow password entries.
  56
  57 =item *
  58
  59 Check group and shadow group files for consistency, as for password and
  60 shadow password files: every group entry has a shadow entry, no passwords in
  61 the group file, no orphaned shadow group entries.
  62
  63 =item *
  64
  65 The lists of group members are consistent between group and shadow group
  66 files; edit the shadow group list to match the main group list where
  67 necessary.
  68
  69 =item *
  70
  71 Group administrators, listed in the shadow group file, are real users; warn
  72 about nonexistent group administrators.
  73
  74 =back
  75
  76 A lot of the checks above only make sense when shadow password and group
  77 files are used.  When instructed not to create shadow files, Shadowfix will
  78 perform the password/group consistency checks as described above.  Also, if
  79 given shadow files as input, and told not to create shadow files on output,
  80 Shadowfix will merge the password information back into the main files.
  81 Obviously, translating shadowed to non-shadowed files involved information
  82 loss: in particular, information about password expiry and group
  83 administration is lost.
  84
  85 It's time to examine the command line options.
  86
  87 =over 4
  88
  89 =item B<--passwd=>I<file>
  90
  91 Use I<file> as the main password file.
  92
  93 =item B<--group=>I<file>
  94
  95 Use I<file> as the main group file.
  96
  97 =item B<--shadow=>I<file>
  98
  99 Use I<file> as the shadow password file.
 100
 101 =item B<--gshadow=>I<file>
 102
 103 Use I<file> as the shadow group file.
 104
 105 =item B<--in-passwd=>I<file>
 106
 107 Read main password file entries from I<file>.
 108
 109 =item B<--in-group=>I<file>
 110
 111 Read main group file entries from I<file>.
 112
 113 =item B<--in-shadow=>I<file>
 114
 115 Read shadow password file entries from I<file>.
 116
 117 =item B<--in-gshadow=>I<file>
 118
 119 Read shadow group file entries from I<file>.
 120
 121 =item B<--quiet>
 122
 123 Suppresses Shadowfix's informative messages about what it's doing to your
 124 passwored files.  Enabling this option is not recommended.
 125
 126 =back
 127
 128 If the input files aren't specified explitly, Shadowfix defaults to trying to
 129 read the output files.  These default sensibly to the system password and
 130 shadow files in F</etc>.
 131
 132 Shadowfix knows about locking password files, so C<passwd> and C<vipw> will
 133 interact with it properly.
 134
 135 =head1 FILES
 136
 137 =over 4
 138
 139 =item F</etc/passwd>, F</etc/shadow>, F</etc/group>, F</etc/gshadow>
 140
 141 System default password and group files.
 142
 143 =back
 144
 145 =head1 BUGS
 146
 147 Shadowfix doesn't understand how to cope with YP password files.  Yellow
 148 Pages is a security hole; don't use it.
 149
 150 =head1 AUTHOR
 151
 152 Mark Wooding, <mdw@distorted.org.uk>
 153
 154 =cut
 155
 156 #----- Configuration section ------------------------------------------------
 157
 158 $passwd = "/etc/passwd";
 159 $group = "/etc/group";
 160 $shadow = "/etc/shadow";
 161 $gshadow = "/etc/gshadow";
 162 $passwd_in = $shadow_in = undef;
 163 $group_in = $gshadow_in = undef;
 164
 165 $suyb = 0;
 166
 167 #----- Subroutines ----------------------------------------------------------
 168
 169 sub hashify {
 170   map { $_, 1 } @_;
 171 }
 172
 173 sub moan {
 174   print STDERR "shadowfix: @_\n";
 175 }
 176
 177 sub uidsort {
 178   if ($a eq $b) {
 179     return 0;
 180   } elsif ($a eq "+") {
 181     return +1;
 182   } elsif ($b eq "+") {
 183     return -1;
 184   } elsif (!exists($ubynam{$a})) {
 185     return +1;
 186   } elsif (!exists($ubynam{$b})) {
 187     return -1;
 188   } else {
 189     return $ubynam{$a}{uid} <=> $ubynam{$b}{uid} || $a cmp $b;
 190   }
 191 }
 192
 193 sub gidsort {
 194   if ($a eq $b) {
 195     return 0;
 196   } elsif ($a eq "+") {
 197     return +1;
 198   } elsif ($b eq "+") {
 199     return -1;
 200   } else {
 201     return $gbynam{$a}{gid} <=> $gbynam{$b}{gid} || $a cmp $b;
 202   }
 203 }
 204
 205 sub lockfile {
 206   my $file = shift;
 207   my $mode = shift or 0644;
 208   my $fh = new FileHandle;
 209
 210   $fh->open("${file}.lock", O_WRONLY | O_EXCL | O_CREAT, 0600) or
 211     die "couldn't obtain lock file ${file}.lock";
 212   $fh->print($$);
 213   $fh->close;
 214   $fh->open("${file}.edit", O_WRONLY | O_TRUNC | O_CREAT, $mode) or do {
 215     unlink "${file}.lock";
 216     die "open(${file}.edit): $!";
 217   };
 218   return $fh;
 219 }
 220
 221 sub unlockfile {
 222   my $file = shift;
 223   my $fh = shift;
 224   $fh->close;
 225
 226   # --- See whether the file changed ---
 227
 228   CHECK: {
 229     my ($ofh, $nfh);
 230     my ($obuf, $nbuf);
 231     my ($osz, $nsz);
 232
 233     # --- Open the old and new versions for reading ---
 234
 235     $ofh = new FileHandle $file, O_RDONLY;
 236     $nfh = new FileHandle "${file}.edit", O_RDONLY;
 237     last CHECK if !$ofh || !$nfh;
 238
 239     # --- Read blocks from each and compare ---
 240
 241     BLOCK: for (;;) {
 242       $osz = sysread($ofh, $obuf, 4096);
 243       $nsz = sysread($nfh, $nbuf, 4096);
 244       last CHECK if !defined($osz) || !defined($nsz);
 245       last CHECK if $obuf ne $nbuf;
 246       last BLOCK if $sz == 0;
 247     }
 248
 249     # --- The files are identical ---
 250
 251     # moan "file $file is unchanged";
 252     unlink("${file}.edit");
 253     unlink("${file}.lock");
 254     return;
 255   }
 256
 257   # --- Find the current owner ---
 258
 259   # system("diff -u $file $file.edit");
 260
 261   if (-e $file) {
 262     my ($mode, $uid, $gid);
 263     (undef, undef, $mode, undef, $uid, $gid) = stat $file;
 264     chmod $mode, "${file}.edit";
 265     chown $uid, $gid, "${file}.edit";
 266   }
 267
 268   # --- Move the old file out of the way ---
 269
 270   !-e $file or rename("${file}", "${file}-") or do {
 271     unlink "${file}.lock";
 272     unlink "${file}.edit";
 273     die "couldn't save backup copy of $file: $!";
 274   };
 275
 276   # --- Move the new one into place ---
 277
 278   rename ("${file}.edit", "${file}") or do {
 279     rename("${file}-", "${file}");      # This shouldn't happen!
 280     unlink "${file}.lock";
 281     unlink "${file}.edit";
 282     die "HELP!!!  couldn't save backup copy of $file: $!";
 283   };
 284
 285   # --- Release the lock ---
 286
 287   moan "updated $file"
 288     unless $suyb;
 289   unlink("${file}.lock");
 290 }
 291
 292 #----- Main code ------------------------------------------------------------
 293
 294 # --- Options parsing ---
 295
 296 $longopts = { 'passwd'          => { return => 'p',  arg => 'opt' },
 297               'in-passwd'       => { return => 'ip', arg => 'opt' },
 298               'shadow'          => { return => 'ps', arg => 'opt' },
 299               'in-shadow'       => { return => 'ips', arg => 'opt' },
 300               'group'           => { return => 'g',  arg => 'opt' },
 301               'in-group'        => { return => 'ig', arg => 'opt' },
 302               'gshadow'         => { return => 'gs', arg => 'opt' },
 303               'in-gshadow'      => { return => 'igs', arg => 'opt' },
 304               'quiet'           => { return => 'q', negate => 1 } };
 305
 306 $opts = MdwOpt->new("", $longopts, \@ARGV, ['negate', 'noshort']);
 307
 308 OPT: while (($opt, $arg) = $opts->read, $opt) {
 309   $passwd = $arg, next OPT if $opt eq 'p';
 310   $passwd_in = $arg, next OPT if $opt eq 'ip';
 311   $shadow = $arg, next OPT if $opt eq 'ps';
 312   $shadow_in = $arg, next OPT if $opt eq 'ips';
 313   $group = $arg, next OPT if $opt eq 'g';
 314   $group_in = $arg, next OPT if $opt eq 'ig';
 315   $gshadow = $arg, next OPT if $opt eq 'gs';
 316   $gshadow_in = $arg, next OPT if $opt eq 'igs';
 317   $suyb = 1, next OPT if $opt eq 'q';
 318   $suyb = 0, next OPT if $opt eq 'q+';
 319   die "bad option";
 320 }
 321
 322 $passwd_in = $passwd unless $passwd_in;
 323 $shadow_in = $shadow unless $shadow_in;
 324 $group_in = $group unless $group_in;
 325 $gshadow_in = $gshadow unless $gshadow_in;
 326
 327 # --- Initialise the user tables ---
 328
 329 %ubynam = %ubyuid = %subynam = ();
 330 %gbynam = %gbygid = %sgbynam = ();
 331
 332 # --- Slurp the user tables into memory ---
 333
 334 $pw = new FileHandle $passwd_in, O_RDONLY or die "open($passwd_in): $!";
 335 while ($line = $pw->getline) {
 336   chomp $line;
 337   my @f = split /:/, $line;
 338   $#f = 6;
 339   $a = { data => [ @f ], name => $f[0], uid => $f[2], gid => $f[3] };
 340   $ubynam{$a->{name}} = $ubyuid{$a->{uid}} = $a;
 341 }
 342 $pw->close;
 343
 344 $gr = new FileHandle $group_in, O_RDONLY or die "open($group_in): $!";
 345 while ($line = $gr->getline) {
 346   chomp $line;
 347   my @f = split /:/, $line;
 348   $#f = 3;
 349   $a = { data => [ @f ],
 350          members => { hashify(split /,/, $f[3]) },
 351          name => $f[0], gid => $f[2] };
 352   $gbynam{$a->{name}} = $gbygid{$a->{gid}} = $a;
 353 }
 354 $gr->close;
 355
 356 undef $have_shadow;
 357 if ($shadow_in) {
 358   if ($spw = new FileHandle $shadow_in, O_RDONLY) {
 359     while ($line = $spw->getline) {
 360       chomp $line;
 361       my @f = split /:/, $line;
 362       $#f = 8;
 363       $a = { data => [ @f ], name => $f[0] };
 364       $subynam{$a->{name}} = $a;
 365     }
 366     $spw->close;
 367     $have_shadow = 1;
 368   } else {
 369     die "open($shadow_in): $!" unless $! == ENOENT;
 370   }
 371 }
 372
 373 undef $have_gshadow;
 374 if ($gshadow_in) {
 375   if ($sgr = new FileHandle $gshadow_in, O_RDONLY) {
 376     while ($line = $sgr->getline) {
 377       chomp $line;
 378       my @f = split /:/, $line;
 379       $#f = 3;
 380       $a = { data => [ @f ],
 381              members => { hashify (split /,/, $f[3]) },
 382              name => $f[0] };
 383       $sgbynam{$a->{name}} = $a;
 384     }
 385     $sgr->close;
 386     $have_gshadow = 1;
 387   } else {
 388     die "open($gshadow_in): $!" unless $! == ENOENT;
 389   }
 390 }
 391
 392 # --- Check primary group memberships ---
 393
 394 for $u (values %ubynam) {
 395   $unam = $u->{name};
 396   if (exists $gbygid{$u->{gid}}) {
 397     $g = $gbygid{$u->{gid}};
 398     unless ($unam eq "+" || exists($g->{members}{$unam})) {
 399       moan "user $unam is not a member of his/her primary group"
 400         unless $suyb;
 401       $g->{members}{$unam} = 1;
 402     }
 403   } else {
 404     moan "user $unam seems to belong to a nonexistant group"
 405       unless $suyb;
 406   }
 407 }
 408
 409 # --- Shadow password checks ---
 410
 411 if ($shadow) {
 412
 413   # --- Full shadowing checks ---
 414
 415   for $u (values %ubynam) {
 416     $unam = $u->{name};
 417
 418     # --- Ensure there's a shadow password entry ---
 419
 420     unless ($unam eq "+" || exists($subynam{$unam})) {
 421       moan "user $unam not in shadow password file: adding"
 422         unless $suyb;
 423       $subynam{$unam} = { name => $unam,
 424                           data => [$unam,
 425                                    $u->{data}[1],
 426                                    10205, 0, 99999, 7, "", "", ""] };
 427     }
 428
 429     # --- Mark unloginable shadow password entries ---
 430
 431     $su = $subynam{$unam};
 432     $p = $su->{data}[1];
 433     if ($p ne "*" && length($p) > 0 && length($p) < 5) {
 434       moan "blanked user ${unam}'s password"
 435         unless $suyb;
 436       $su->{data}[1] = "*";
 437     }
 438
 439     # --- Blank out normal password entries ---
 440
 441     if ($unam eq "+") {
 442       # Nothing doing
 443     } elsif ($p eq "") {
 444       $u->{data}[1] = "";
 445     } else {
 446       $u->{data}[1] = "x";
 447     }
 448   }
 449
 450   # --- Remove shadow entries which don't make sense any more ---
 451
 452   for $su (values %subynam) {
 453     $unam = $su->{name};
 454     unless (exists($ubynam{$unam})) {
 455       moan "user $unam only in shadow password file: deleting"
 456         unless $suyb;
 457       delete $subynam{$su->{name}};
 458     }
 459   }
 460
 461 } elsif ($have_shadow) {
 462
 463   # --- We have shadowing, but aren't writing out entries ---
 464
 465   for $u (values %ubynam) {
 466     $unam = $u->{name};
 467     $u->{data}[1] = $subynam{$unam}{data}[1]
 468       if exists($subynam{$unam});
 469   }
 470 }
 471
 472 # --- Shadow group checks ---
 473
 474 for $g (values %gbynam) {
 475   $gnam = $g->{name};
 476
 477   # --- Ensure there's a shadow group entry ---
 478
 479   unless (!$gshadow || $gnam eq "+" || exists($sgbynam{$gnam})) {
 480     moan "group $gnam not in shadow group file: adding"
 481       unless $suyb;
 482     $sgbynam{$gnam} = { name => $gnam,
 483                         data => [$gnam,
 484                                  $g->{data}[1],
 485                                  "",
 486                                  $g->{data}[3]],
 487                         members => { %{$g->{members}} } };
 488   }
 489
 490   # --- Play games with passwords ---
 491
 492   if ($gshadow) {
 493
 494     # --- Mark unloginable shadow group entries ---
 495
 496     $sg = $sgbynam{$gnam};
 497     $p = $sg->{data}[1];
 498     if ($p ne "*" && length($p) > 0 && length($p) < 5) {
 499       moan "blanked group ${gnam}'s password"
 500         unless $suyb;
 501       $sg->{data}[1] = "*";
 502     }
 503
 504     # --- Blank out normal passwords ---
 505
 506     $g->{data}[1] = "x" unless $gnam eq "+";
 507
 508     # --- Check that the group's administrators exist ---
 509
 510     if ($sg->{data}[2] ne "" && !$suyb) {
 511       my @admins =
 512       my $admin;
 513       foreach $admin (split(/,/, $sg->{data}[2])) {
 514         exists $ubynam{$admin} or
 515           moan "user $admin owns group $gnam but doesn't seem to exist";
 516       }
 517     }
 518
 519   } elsif ($have_gshadow) {
 520     $g->{data}[1] = $sgbynam{$gnam}{data}[1]
 521       if exists($sgbynam{$gnam});
 522     $sg = undef;
 523   }
 524
 525   # --- The group members should be consistent across both files ---
 526
 527   for $i (keys %{$g->{members}}) {
 528     exists $ubynam{$i} or $suyb or
 529       moan "user $i is a member of group $gnam but doesn't seem to exist";
 530     unless (!$sg || exists($sg->{members}{$i})) {
 531       moan "group $gnam does not include $i in shadow group file: adding"
 532         unless $suyb;
 533       $sg->{members}{$i} = 1;
 534     }
 535   }
 536   if ($sg) {
 537     for $i (keys %{$sg->{members}}) {
 538       unless (exists($g->{members}{$i})) {
 539         moan "group $gnam does not include $i in main group file: deleting"
 540           unless $suyb;
 541         delete $sg->{members}{$i};
 542       }
 543     }
 544   }
 545 }
 546
 547 # --- Remove entries which are only in the shadow file ---
 548
 549 if ($gshadow) {
 550   for $sg (values %sgbynam) {
 551     $gnam = $sg->{name};
 552     unless (exists($gbynam{$gnam})) {
 553       moan "group $gnam only in shadow group file: deleting"
 554         unless $suyb;
 555       delete $sgbynam{$gnam};
 556     }
 557   }
 558 }
 559
 560 # --- Fix up the data blocks ---
 561
 562 for $g (values %gbynam) {
 563   $g->{data}[3] = join(",", sort uidsort keys %{$g->{members}});
 564 }
 565
 566 if ($gshadow) {
 567   for $sg (values %sgbynam) {
 568     $sg->{data}[3] = join(",", sort uidsort keys %{$sg->{members}});
 569   }
 570 }
 571
 572 # --- Output the finished work of art ---
 573
 574 $pw = lockfile($passwd, 0644);
 575 for $unam (sort uidsort keys %ubynam) {
 576   $pw->print(join(":", @{$ubynam{$unam}{data}}), "\n");
 577 }
 578 unlockfile($passwd, $pw);
 579
 580 if ($shadow) {
 581   $spw = lockfile($shadow, 0640);
 582   for $unam (sort uidsort keys %subynam) {
 583     $spw->print(join(":", @{$subynam{$unam}{data}}), "\n");
 584   }
 585   unlockfile($shadow, $spw);
 586 }
 587
 588 $gr = lockfile($group, 0644);
 589 for $gnam (sort gidsort keys %gbynam) {
 590   $gr->print(join(":", @{$gbynam{$gnam}{data}}), "\n");
 591 }
 592 unlockfile($group, $gr);
 593
 594 if ($gshadow) {
 595   $sgr = lockfile($gshadow, 0640);
 596   for $gnam (sort gidsort keys %sgbynam) {
 597     $sgr->print(join(":", @{$sgbynam{$gnam}{data}}), "\n");
 598   }
 599   unlockfile($gshadow, $sgr);
 600 }
 601
 602 #----- More subroutines -----------------------------------------------------
 603
 604 sub udump {
 605   my $u = shift;
 606   printf "name = %s\n", $u->{name};
 607   printf "uid = %d, gid = %d\n", $u->{uid}, $u->{gid};
 608   printf "data = %s\n", join(":", @{$u->{data}});
 609   print "\n";
 610 }
 611
 612 sub sudump {
 613   my $u = shift;
 614   printf "name = %s\n", $u->{name};
 615   printf "data = %s\n", join(":", @{$u->{data}});
 616   print "\n";
 617 }
 618
 619 sub gdump {
 620   my $g = shift;
 621   printf "name = %s\n", $g->{name};
 622   printf "gid = %d\n", $g->{gid};
 623   printf "members = %s\n", join(",", sort uidsort keys %{$g->{members}});
 624   printf "data = %s\n", join(":", @{$g->{data}});
 625   print "\n";
 626 }
 627
 628 sub sgdump {
 629   my $g = shift;
 630   printf "name = %s\n", $g->{name};
 631   printf "members = %s\n", join(",", sort uidsort keys %{$g->{members}});
 632   printf "data = %s\n", join(":", @{$g->{data}});
 633   print "\n";
 634 }
 635
 636 #----- That's all, folks ----------------------------------------------------