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- #!/usr/bin/perl -w
-
- # pam-auth-update: update /etc/pam.d/common-* from /usr/share/pam-configs
- #
- # Update the /etc/pam.d/common-* files based on the per-package profiles
- # provided in /usr/share/pam-configs/ taking into consideration user's
- # preferences (as determined via debconf prompting).
- #
- # Written by Steve Langasek <steve.langasek@canonical.com>
- #
- # Copyright (C) 2008 Canonical Ltd.
- #
- # This program is free software; you can redistribute it and/or modify
- # it under the terms of version 3 of the GNU General Public License as
- # published by the Free Software Foundation.
- #
- # # This program is distributed in the hope that it will be useful,
- # but WITHOUT ANY WARRANTY; without even the implied warranty of
- # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- # GNU General Public License for more details.
- #
- # You should have received a copy of the GNU General Public License
- # along with this program; if not, write to the Free Software
- # Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301,
- # USA.
-
- use strict;
- use Debconf::Client::ConfModule ':all';
- use IPC::Open2 'open2';
-
- version('2.0');
- my $capb=capb('backup');
-
- my $inputdir = '/usr/share/pam-configs';
- my $template = 'libpam-runtime/profiles';
- my $errtemplate = 'libpam-runtime/conflicts';
- my $overridetemplate = 'libpam-runtime/override';
- my $blanktemplate = 'libpam-runtime/no_profiles_chosen';
- my $confdir = '/etc/pam.d';
- my $savedir = '/var/lib/pam';
- my (%profiles, @sorted, @enabled, @conflicts, %removals);
- my $force = 0;
- my $priority = 'high';
- my %md5sums = (
- 'auth' => [
- '8d4fe17e66ba25de16a117035d1396aa',
- '1fd1e8e87cef1c13898410d830229122',
- ],
- 'account' => [
- '3c0c362eaf3421848b679d63fd48c3fa',
- '8a29dc79152ce8441aa90a8f8650d076',
- ],
- 'password' => [
- '50fce2113dfda83ac8bdd5a6e706caec',
- '4bd7610f2e85f8ddaef79c7db7cb49eb',
- '9ba753d0824276b44bcadfee1f87b6bc',
- ],
- 'session' => [
- '240fb92986c885b327cdb21dd641da8c',
- '4a25673e8b36f1805219027d3be02cd2',
- ],
- 'session-noninteractive' => [
- 'ad2b78ce1498dd637ef36469430b6ac6',
- ],
- );
-
- opendir(DIR, $inputdir) || die "could not open config directory: $!";
- while (my $profile = readdir(DIR)) {
- next if ($profile eq '.' || $profile eq '..');
- %{$profiles{$profile}} = parse_pam_profile($inputdir . '/' . $profile);
- }
- closedir DIR;
-
- # use a '--force' arg to specify that /etc/pam.d should be overwritten;
- # used only on upgrades where the postinst has already determined that the
- # checksums match. Module packages other than libpam-runtime itself must
- # NEVER use this option! Document with big skullses and crossboneses! It
- # needs to be exposed for libpam-runtime because that's the package that
- # decides whether we have a pristine config to be converted, and knows
- # whether the version being upgraded from is one for which the conversion
- # should be done.
-
- while ($#ARGV >= 0) {
- my $opt = shift;
- if ($opt eq '--force') {
- $force = 1;
- } elsif ($opt eq '--package') {
- $priority = 'medium';
- } elsif ($opt eq '--remove') {
- while ($#ARGV >= 0) {
- last if ($ARGV[0] =~ /^--/);
- $removals{shift @ARGV} = 1;
- }
- # --remove implies --package
- $priority = 'medium' if (keys(%removals));
- }
- }
-
- x_loadtemplatefile('/var/lib/dpkg/info/libpam-runtime.templates','libpam-runtime');
-
- # always sort by priority, so we have consistency and don't have to
- # shuffle later
- @sorted = sort { $profiles{$b}->{'Priority'} <=> $profiles{$a}->{'Priority'}
- || $b cmp $a }
- keys(%profiles);
- # If we're being called for package removal, filter out those options here
- @sorted = grep { !$removals{$_} } @sorted;
-
- subst($template, 'profile_names', join(', ',@sorted));
- subst($template, 'profiles',
- join(', ', map { $profiles{$_}->{'Name'} } @sorted));
-
- my $diff = diff_profiles($confdir,$savedir);
-
- if ($diff) {
- @enabled = grep { !$removals{$_} } @{$diff->{'mods'}};
- } else {
- @enabled = split(/, /,get($template));
- }
-
- # find out what we've seen, so we can ignore those defaults
- my %seen;
- if (-e $savedir . '/seen') {
- open(SEEN,$savedir . '/seen');
- while (<SEEN>) {
- chomp;
- $seen{$_} = 1;
- }
- close(SEEN);
- }
-
- # filter out any options that are no longer available for any reason
- @enabled = grep { $profiles{$_} } @enabled;
-
- # an empty module set is an error, so in that case grab all the defaults
- if (!@enabled) {
- %seen = ();
- $priority = 'high' unless ($force);
- }
-
- # add any previously-unseen configs
- push(@enabled,
- grep { $profiles{$_}->{'Default'} eq 'yes' && !$seen{$_} } @sorted);
- @enabled = sort { $profiles{$b}->{'Priority'} <=> $profiles{$a}->{'Priority'}
- || $b cmp $a }
- @enabled;
- my $prev = '';
- @enabled = grep { $_ ne $prev && (($prev) = $_) } @enabled;
-
-
- fset($template,'seen','false');
- set($template,join(', ', @enabled));
-
- # if diff_profiles() fails, and we weren't passed a 'force' argument
- # (because this isn't an upgrade from an old version, or the checksum
- # didn't match, or we're being called by some other module package), prompt
- # the user whether to override. If the user declines (the default), we
- # never again manage this config unless manually called with '--force'.
- if (!$diff && !$force) {
- input('high',$overridetemplate);
- go();
- $force = 1 if (get($overridetemplate) eq 'true');
- }
-
- if (!$diff && !$force) {
- print STDERR <<EOF;
-
- pam-auth-update: Local modifications to /etc/pam.d/common-*, not updating.
- pam-auth-update: Run pam-auth-update --force to override.
-
- EOF
- exit;
- }
-
- umask(0022);
-
- do {
- @conflicts = ();
- input($priority,$template);
- go();
-
- @enabled = split(/, /, get($template));
-
- # in case of conflicts, automatically unset the lower priority
- # item of each pair
- foreach my $elem (@enabled)
- {
- for (my $i=$#enabled; $i >= 0; $i--)
- {
- my $conflict = $enabled[$i];
- if ($profiles{$elem}->{'Conflicts'}->{$conflict}) {
- splice(@enabled,$i,1);
- my $desc = $profiles{$elem}->{'Name'}
- . ', ' . $profiles{$conflict}->{'Name'};
- push(@conflicts,$desc);
- }
- }
- }
- if (@conflicts) {
- subst($errtemplate, 'conflicts', join("\n", @conflicts));
- input('high',$errtemplate);
- }
- fset($template,'seen','false');
- set($template, join(', ', @enabled));
- if (!@enabled) {
- input('high',$blanktemplate);
- }
- } while (@conflicts || !@enabled);
-
- # the decision has been made about what configs to use, so even if
- # something fails after this, we shouldn't go munging the default
- # options again. Save the list of known configs to /var/lib/pam.
- open(SEEN,"> $savedir/seen");
- for my $i (@sorted) {
- print SEEN "$i\n";
- }
- close(SEEN);
-
- # @enabled now contains our list of profiles to use for piecing together
- # a config
- # we have:
- # - templates into which we insert the specialness
- # - magic comments denoting the beginning and end of our managed block;
- # looking at only the functional config lines would potentially let us
- # handle more cases, at the expense of much greater complexity, so
- # pass on this at least for the first round
- # - a representation of the autogenerated config stored in /var/lib/pam,
- # that we can diff against in order to account for changed options or
- # manually dropped modules
- # - a hash describing the local modifications the user has made to the
- # config; these are always preserved unless manually overridden with
- # the --force option
-
- write_profiles(\%profiles, \@enabled, $confdir, $savedir, $diff, $force);
-
-
- # take a single line from a stock config, and merge it with the
- # information about local admin edits
- sub merge_one_line
- {
- my ($line,$diff,$count) = @_;
- my (@opts,$modline);
-
- my ($adds,$removes);
-
- $line =~ /^((\[[^]]+\]|\w+)\s+\S+)\s*(.*)/;
-
- @opts = split(/\s+/,$3);
- $modline = $1;
- $modline =~ s/end/$count/g;
- if ($diff) {
- my $mod = $modline;
- $mod =~ s/[0-9]+//g;
- $adds = \%{$diff->{'add'}{$mod}};
- $removes = \%{$diff->{'remove'}{$mod}};
- } else {
- $adds = $removes = undef;
- }
-
- for (my $i = 0; $i <= $#opts; $i++) {
- if ($adds->{$opts[$i]}) {
- delete $adds->{$opts[$i]};
- }
- if ($removes->{$opts[$i]}) {
- splice(@opts,$i,1);
- $i--;
- }
- }
- return $modline . " " . join(' ',@opts,keys(%{$adds})) . "\n";
- }
-
- # return the lines for a given config name, type, and position in the stack
- sub lines_for_module_and_type
- {
- my ($profiles, $mod, $type, $modpos) = @_;
- if ($modpos == 0 && $profiles->{$mod}{$type . '-Initial'}) {
- return $profiles->{$mod}{$type . '-Initial'};
- }
- return $profiles->{$mod}{$type};
- }
-
- # create a single PAM config from the indicated template and selections,
- # writing to a new file
- sub create_from_template
- {
- my($template,$dest,$profiles,$enabled,$diff,$type) = @_;
- my $state = 0;
- my $uctype = ucfirst($type);
- $type =~ s/-noninteractive//;
-
- open(INPUT,$template) || return 0;
- open(OUTPUT,">$dest") || return 0;
-
- while (<INPUT>) {
- if ($state == 1) {
- if (/^# here's the fallback if no module succeeds/) {
- print OUTPUT;
- $state++;
- }
- next;
- }
- if ($state == 3) {
- if (/^# end of pam-auth-update config/) {
- print OUTPUT;
- $state++;
- }
- next;
- }
-
- print OUTPUT;
-
- my ($pattern,$val);
- if ($state == 0) {
- $pattern = '^# here are the per-package modules \(the "Primary" block\)';
- $val = 'Primary';
- } elsif ($state == 2) {
- $pattern = '^# and here are more per-package modules \(the "Additional" block\)';
- $val = 'Additional';
- } else {
- next;
- }
-
- if (/$pattern/) {
- my $i = 0;
- my $count = 0;
- # first we need to get a count of lines that we're
- # going to output, so we can fix up the jumps correctly
- for my $mod (@{$enabled}) {
- my $output;
- next if (!$profiles->{$mod}{$uctype . '-Type'});
- next if $profiles->{$mod}{$uctype . '-Type'} ne $val;
- $output = lines_for_module_and_type($profiles, $mod, $uctype, $i++);
- # bypasses a perl warning about @_, sigh
- my @tmparr = split("\n+",$output);
- $count += @tmparr;
- }
-
- # in case anything tries to jump in the 'additional'
- # block, let's try not to jump off the stack...
- $count-- if ($val eq 'Additional');
-
- # no primary block, so output a stock pam_permit line
- # to keep the stack intact
- if ($val eq 'Primary' && $count == 0)
- {
- print OUTPUT "$type\t[default=1]\t\t\tpam_permit.so\n";
- }
-
- $i = 0;
- for my $mod (@{$enabled}) {
- my $output;
- my @output;
- next if (!$profiles->{$mod}{$uctype . '-Type'});
- next if $profiles->{$mod}{$uctype . '-Type'} ne $val;
- $output = lines_for_module_and_type($profiles, $mod, $uctype, $i++);
- for my $line (split("\n",$output)) {
- $line = merge_one_line($line,$diff,
- $count);
- print OUTPUT "$type\t$line";
- $count--;
- }
- }
- $state++;
- }
- }
- close(INPUT);
- close(OUTPUT);
-
- if ($state < 4) {
- unlink($dest);
- return 0;
- }
- return 1;
- }
-
- # take a template file, strip out everything between the markers, and
- # return the md5sum of the remaining contents. Used for testing for
- # local modifications of the boilerplate.
- sub get_template_md5sum
- {
- my($template) = @_;
- my $state = 0;
-
- open(INPUT,$template) || return '';
- my($md5sum_fd,$output_fd);
- my $pid = open2($md5sum_fd, $output_fd, 'md5sum');
- return '' if (!$pid);
-
- while (<INPUT>) {
- if ($state == 1) {
- if (/^# here's the fallback if no module succeeds/) {
- print $output_fd $_;
- $state++;
- }
- next;
- }
- if ($state == 3) {
- if (/^# end of pam-auth-update config/) {
- print $output_fd $_;
- $state++;
- }
- next;
- }
-
- print $output_fd $_;
-
- my ($pattern,$val);
- if ($state == 0) {
- $pattern = '^# here are the per-package modules \(the "Primary" block\)';
- } elsif ($state == 2) {
- $pattern = '^# and here are more per-package modules \(the "Additional" block\)';
- } else {
- next;
- }
-
- if (/$pattern/) {
- $state++;
- }
- }
- close(INPUT);
- close($output_fd);
- my $md5sum = <$md5sum_fd>;
- close($md5sum_fd);
- waitpid $pid, 0;
-
- $md5sum = (split(/\s+/,$md5sum))[0];
- return $md5sum;
- }
-
- # merge a set of module declarations into a set of new config files,
- # using the information returned from diff_profiles().
- sub write_profiles
- {
- my($profiles,$enabled,$confdir,$savedir,$diff,$force) = @_;
-
- if (! -d $savedir) {
- mkdir($savedir);
- }
-
- # because we can't atomically replace both /var/lib/pam/$foo and
- # /etc/pam.d/common-$foo at the same time, take steps to make this
- # somewhat robust
- for my $type ('auth','account','password','session',
- 'session-noninteractive')
- {
- my $target = $confdir . '/common-' . $type;
- my $template = $target;
- my $dest = $template . '.pam-new';
-
- my $diff = $diff;
- if ($diff) {
- $diff = \%{$diff->{$type}};
- }
-
- # Detect if the template is unmodified, and if so, use
- # the version from /usr/share. Depends on knowing the
- # md5sums of the originals.
- my $md5sum = get_template_md5sum($template);
- for my $i (@{$md5sums{$type}}) {
- if ($md5sum eq $i) {
- $template = '/usr/share/pam/common-' . $type;
- last;
- }
- }
-
- # first, write out the new config
- if (!create_from_template($template,$dest,$profiles,$enabled,
- $diff,$type))
- {
- if (!$force) {
- return 0;
- }
- $template = '/usr/share/pam/common-' . $type;
- if (!create_from_template($template,$dest,$profiles,
- $enabled,$diff,$type))
- {
- return 0;
- }
- }
-
- # then write out the saved config
- if (!open(OUTPUT, "> $savedir/$type.new")) {
- unlink($dest);
- return 0;
- }
- my $i = 0;
- my $uctype = ucfirst($type);
- for my $mod (@{$enabled}) {
- my $output;
- next if (!$profiles->{$mod}{$uctype . '-Type'});
- next if ($profiles->{$mod}{$uctype . '-Type'} eq 'Additional');
-
- $output = lines_for_module_and_type($profiles, $mod, $uctype, $i++);
- if ($output) {
- print OUTPUT "Module: $mod\n";
- print OUTPUT $output . "\n";
- }
- }
-
- # no primary block, so output a stock pam_permit line
- if ($i == 0)
- {
- print OUTPUT "Module: null\n";
- print OUTPUT "[default=1]\t\t\tpam_permit.so\n";
- }
-
- $i = 0;
- for my $mod (@{$enabled}) {
- my $output;
- next if (!$profiles->{$mod}{$uctype . '-Type'});
- next if ($profiles->{$mod}{$uctype . '-Type'} eq 'Primary');
-
- $output = lines_for_module_and_type($profiles, $mod, $uctype, $i++);
- if ($output) {
- print OUTPUT "Module: $mod\n";
- print OUTPUT $output . "\n";
- }
- }
-
- close(OUTPUT);
-
- # then do the renames, back-to-back
- # we have to use system because File::Copy is in
- # perl-modules, not perl-base
- if (-e "$target" && $force) {
- system('cp','-f',$target,$target . '.pam-old');
- }
- rename($dest,$target);
- rename("$savedir/$type.new","$savedir/$type");
- }
-
- # at the end of a successful write, reset the 'seen' flag and the
- # value of the debconf override question.
- fset($overridetemplate,'seen','false');
- set($overridetemplate,'false');
- }
-
- # reconcile the current config in /etc/pam.d with the saved ones in
- # /var/lib/pam; returns a hash of profile names and the corresponding
- # options that should be added/removed relative to the stock config.
- # returns false if any of the markers are missing that permit a merge,
- # or on any other failure.
- sub diff_profiles
- {
- my ($sourcedir,$savedir) = @_;
- my (%diff);
-
- @{$diff{'mods'}} = ();
- # Load the saved config from /var/lib/pam, then iterate through all
- # lines in the current config that are in the managed block.
- # If anything fails here, just return immediately since we then
- # have nothing to merge; instead, the caller will decide later
- # whether to force an overwrite.
- for my $type ('auth','account','password','session',
- 'session-noninteractive')
- {
- my (@saved,$modname);
-
- open(SAVED,$savedir . '/' . $type) || return 0;
- while (<SAVED>) {
- if (/^Module: (.*)/) {
- $modname = $1;
- next;
- }
- chomp;
- # trim out the destination of any jumps; this saves
- # us from having to re-parse everything just to fix
- # up the jump lengths, when changes to these will
- # already show up as inconsistencies elsewhere
- s/(\[[^0-9]*)[0-9]+(.*\])/$1$2/g;
- s/(\[.*)end(.*\])/$1$2/g;
- my (@temp) = ($modname,$_);
- push(@saved,\@temp);
- }
- close(SAVED);
-
- my $state = 0;
- my (@prev_opts,$curmod);
- my $realtype = $type;
- $realtype =~ s/-noninteractive//;
-
- open(CURRENT,$sourcedir . '/common-' . $type) || return 0;
- while (<CURRENT>) {
- if ($state == 0) {
- $state = 1
- if (/^# here are the per-package modules \(the "Primary" block\)/);
- next;
- }
- if ($state == 1) {
- s/^$realtype\s+//;
- if (/^# here's the fallback if no module succeeds/) {
- $state = 2;
- next;
- }
- }
- if ($state == 2) {
- $state = 3
- if (/^# and here are more per-package modules \(the "Additional" block\)/);
- next;
- }
- if ($state == 3) {
- last if (/^# end of pam-auth-update config/);
- s/^$realtype\s+//;
- }
-
- my $found = 0;
- my $curopts;
- while (!$found && $#saved >= 0) {
- my $line;
- ($modname,$line) = @{$saved[0]};
- shift(@saved);
- $line =~ /^((\[[^]]+\]|\w+)\s+\S+)\s*(.*)/;
- @prev_opts = split(/\s+/,$3);
- $curmod = $1;
- # FIXME: the key isn't derived from the config
- # name, so collisions are possible if more
- # than one config references the same module
-
- $_ =~ s/(\[[^0-9]*)[0-9]+(.*\])/$1$2/g;
- # check if this is a match for the current line
- if ($_ =~ /^\Q$curmod\E\s*(.*)$/) {
- $found = 1;
- $curopts = $1;
- push(@{$diff{'mods'}},$modname);
- }
- }
-
- # there's a line in the live config that doesn't
- # correspond to anything from the saved config.
- # treat this as a failure; it's very error-prone
- # to decide what to do with an added line that
- # didn't come from a package.
- return 0 if (!$found);
-
- for my $opt (split(/\s+/,$curopts)) {
- my $found = 0;
- for (my $i = 0; $i <= $#prev_opts; $i++) {
- if ($prev_opts[$i] eq $opt) {
- $found = 1;
- splice(@prev_opts,$i,1);
- }
- }
- $diff{$type}{'add'}{$curmod}{$opt} = 1 if (!$found);
- }
- for my $opt (@prev_opts) {
- $diff{$type}{'remove'}{$curmod}{$opt} = 1;
- }
- }
- close(CURRENT);
-
- # we couldn't parse the config, so the merge fails
- return 0 if ($state < 3);
- }
- return \%diff;
- }
-
- # simple function to parse a provided config file, in pseudo-RFC822
- # format,
- sub parse_pam_profile
- {
- my ($profile) = $_[0];
- my $fieldname;
- my %profile;
- open(PROFILE, $profile) || die "could not read profile $profile: $!";
- while (<PROFILE>) {
- if (/^(\S+):\s+(.*)$/) {
- $fieldname = $1;
- # compatibility with the first implementation round;
- # "Auth-Final" is now just called "Auth"
- $fieldname =~ s/-Final$//;
- if ($fieldname eq 'Conflicts') {
- foreach my $elem (split(/, /, $2)) {
- $profile{'Conflicts'}->{$elem} = 1;
- }
- } else {
- $profile{$fieldname} = $2;
- }
- } else {
- chomp;
- s/^\s+//;
- $profile{$fieldname} .= "\n$_";
- $profile{$fieldname} =~ s/^[\n\s]+//;
- }
- }
- close(PROFILE);
- if (!defined($profile{'Session-Interactive-Only'})) {
- $profile{'Session-noninteractive-Type'} = $profile{'Session-Type'};
- $profile{'Session-noninteractive'} = $profile{'Session'};
- $profile{'Session-noninteractive-Initial'} = $profile{'Session-Initial'};
- }
- return %profile;
- }
-