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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 escape'); 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 $titletemplate = 'libpam-runtime/title'; my $confdir = '/etc/pam.d'; my $savedir = '/var/lib/pam'; my (%profiles, @sorted, @enabled, @conflicts, @new, %removals); my $force = 0; my $package = 0; my $priority = 'high'; my %md5sums = ( 'auth' => ['8d4fe17e66ba25de16a117035d1396aa'], 'account' => ['3c0c362eaf3421848b679d63fd48c3fa'], 'password' => [ '50fce2113dfda83ac8bdd5a6e706caec', '4bd7610f2e85f8ddaef79c7db7cb49eb', '9ba753d0824276b44bcadfee1f87b6bc', ], 'session' => [ '240fb92986c885b327cdb21dd641da8c', '4a25673e8b36f1805219027d3be02cd2', '73144a2f4e609a922a51e301cd66a57e', ], 'session-noninteractive' => [ 'ad2b78ce1498dd637ef36469430b6ac6', 'a20e8df3469bfe25c13a3b39161b30f0', ], ); 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') { $package = 1; } elsif ($opt eq '--remove') { while ($#ARGV >= 0) { last if ($ARGV[0] =~ /^--/); $removals{shift @ARGV} = 1; } # --remove implies --package $package = 1 if (keys(%removals)); } } $priority = 'medium' if ($package); 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) = $_) } @enabled; # Do we have any new options to show? If not, we shouldn't reprompt the # user, at any priority level, unless explicitly called. @new = grep { !$seen{$_} } @sorted; settitle($titletemplate); # 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 = (); if (@new || !$package) { fset($template,'seen','false'); } set($template,join(', ', @enabled)); input($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',$errtemplate); } set($template, join(', ', @enabled)); if (!@enabled) { input('high',$blanktemplate); # we can only end up here by user error, but give them another # shot at selecting a correct config anyway. fset($template,'seen','false'); } } 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/(\[[^0-9]*)[0-9]+(.*\])/$1$2/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 $modline . " " . join(' ',@opts,sort keys(%{$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$_" if ($_); $profile{$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; }