- print "Processing $setup as user ".username()." ...\n";
- my $ret=system("ikiwiki", "-setup", $setup, @ARGV);
- if ($ret != 0) {
- print STDERR "warning: processing $setup failed with code $ret\n";
+ print "Processing $setup as user $user ...\n";
+ # su is not used because it passes arguments through the shell,
+ # which is not safe for untrusted setup file names.
+ defined(my $pid = fork) or die "Can’t fork: $!";
+ if (! $pid) {
+ my ($uuid, $ugid) = (getpwnam($user))[2, 3];
+ my $grouplist=join(" ", $ugid, sort {$a <=> $b} $ugid, supplemental_groups($user));
+ if (! samelists(($)=$grouplist), $grouplist)) {
+ die "failed to set egid $grouplist (got back $))";
+ }
+ $(=$ugid;
+ $<=$uuid;
+ $>=$uuid;
+ if ($< != $uuid || $> != $uuid || $( != $ugid) {
+ die "failed to drop permissions to $user";
+ }
+ %ENV=(
+ PATH => $ENV{PATH},
+ HOME => (getpwnam($user))[7],
+ );
+ exec("ikiwiki", "-setup", $setup, @ARGV);
+ die "failed to run ikiwiki: $!";