IkiWiki/Wrapper.pm

   1 #!/usr/bin/perl
   2
   3 package IkiWiki;
   4
   5 use warnings;
   6 use strict;
   7 use File::Spec;
   8 use Data::Dumper;
   9 use IkiWiki;
  10
  11 sub gen_wrappers () {
  12         debug(gettext("generating wrappers.."));
  13         my %origconfig=(%config);
  14         foreach my $wrapper (@{$config{wrappers}}) {
  15                 %config=(%origconfig, %{$wrapper});
  16                 $config{verbose}=$config{setupverbose}
  17                         if exists $config{setupverbose};
  18                 $config{syslog}=$config{setupsyslog}
  19                         if exists $config{setupsyslog};
  20                 delete @config{qw(setupsyslog setupverbose wrappers genwrappers rebuild)};
  21                 checkconfig();
  22                 if (! $config{cgi} && ! $config{post_commit} &&
  23                     ! $config{test_receive}) {
  24                         $config{post_commit}=1;
  25                 }
  26                 gen_wrapper();
  27         }
  28         %config=(%origconfig);
  29 }
  30
  31 sub gen_wrapper () {
  32         $config{srcdir}=File::Spec->rel2abs($config{srcdir});
  33         $config{destdir}=File::Spec->rel2abs($config{destdir});
  34         my $this=File::Spec->rel2abs($0);
  35         if (! -x $this) {
  36                 error(sprintf(gettext("%s doesn't seem to be executable"), $this));
  37         }
  38
  39         if ($config{setup}) {
  40                 error(gettext("cannot create a wrapper that uses a setup file"));
  41         }
  42         my $wrapper=possibly_foolish_untaint($config{wrapper});
  43         if (! defined $wrapper || ! length $wrapper) {
  44                 error(gettext("wrapper filename not specified"));
  45         }
  46         delete $config{wrapper};
  47
  48         my @envsave;
  49         push @envsave, qw{REMOTE_ADDR QUERY_STRING REQUEST_METHOD REQUEST_URI
  50                        CONTENT_TYPE CONTENT_LENGTH GATEWAY_INTERFACE
  51                        HTTP_COOKIE REMOTE_USER HTTPS REDIRECT_STATUS
  52                        REDIRECT_URL} if $config{cgi};
  53         my $envsave="";
  54         foreach my $var (@envsave) {
  55                 $envsave.=<<"EOF";
  56         if ((s=getenv("$var")))
  57                 addenv("$var", s);
  58 EOF
  59         }
  60
  61         my @wrapper_hooks;
  62         run_hooks(genwrapper => sub { push @wrapper_hooks, shift->() });
  63
  64         my $check_commit_hook="";
  65         my $pre_exec="";
  66         if ($config{post_commit}) {
  67                 # Optimise checking !commit_hook_enabled() ,
  68                 # so that ikiwiki does not have to be started if the
  69                 # hook is disabled.
  70                 #
  71                 # Note that perl's flock may be implemented using fcntl
  72                 # or lockf on some systems. If so, and if there is no
  73                 # interop between the locking systems, the true C flock will
  74                 # always succeed, and this optimisation won't work.
  75                 # The perl code will later correctly check the lock,
  76                 # so the right thing will still happen, though without
  77                 # the benefit of this optimisation.
  78                 $check_commit_hook=<<"EOF";
  79         {
  80                 int fd=open("$config{wikistatedir}/commitlock", O_CREAT | O_RDWR, 0666);
  81                 if (fd != -1) {
  82                         if (flock(fd, LOCK_SH | LOCK_NB) != 0)
  83                                 exit(0);
  84                         close(fd);
  85                 }
  86         }
  87 EOF
  88         }
  89         elsif ($config{cgi}) {
  90                 # Avoid more than one ikiwiki cgi running at a time by
  91                 # taking a cgi lock. Since ikiwiki uses several MB of
  92                 # memory, a pile up of processes could cause thrashing
  93                 # otherwise. The fd of the lock is stored in
  94                 # IKIWIKI_CGILOCK_FD so unlockwiki can close it.
  95                 $pre_exec=<<"EOF";
  96         lockfd=open("$config{wikistatedir}/cgilock", O_CREAT | O_RDWR, 0666);
  97         if (lockfd != -1 && flock(lockfd, LOCK_EX) == 0) {
  98                 char *fd_s=malloc(8);
  99                 sprintf(fd_s, "%i", lockfd);
 100                 setenv("IKIWIKI_CGILOCK_FD", fd_s, 1);
 101         }
 102 EOF
 103         }
 104
 105         my $set_background_command='';
 106         if (defined $config{wrapper_background_command} &&
 107             length $config{wrapper_background_command}) {
 108                 my $background_command=delete $config{wrapper_background_command};
 109                 $set_background_command=~s/"/\\"/g;
 110                 $set_background_command='#define BACKGROUND_COMMAND "'.$background_command.'"';
 111         }
 112
 113         $Data::Dumper::Indent=0; # no newlines
 114         my $configstring=Data::Dumper->Dump([\%config], ['*config']);
 115         $configstring=~s/\\/\\\\/g;
 116         $configstring=~s/"/\\"/g;
 117         $configstring=~s/\n/\\n/g;
 118
 119         writefile(basename("$wrapper.c"), dirname($wrapper), <<"EOF");
 120 /* A wrapper for ikiwiki, can be safely made suid. */
 121 #include <stdio.h>
 122 #include <sys/types.h>
 123 #include <sys/stat.h>
 124 #include <fcntl.h>
 125 #include <unistd.h>
 126 #include <stdlib.h>
 127 #include <string.h>
 128 #include <sys/file.h>
 129
 130 extern char **environ;
 131 char *newenviron[$#envsave+7];
 132 int i=0;
 133
 134 void addenv(char *var, char *val) {
 135         char *s=malloc(strlen(var)+1+strlen(val)+1);
 136         if (!s)
 137                 perror("malloc");
 138         sprintf(s, "%s=%s", var, val);
 139         newenviron[i++]=s;
 140 }
 141
 142 int main (int argc, char **argv) {
 143         int lockfd=-1;
 144         char *s;
 145
 146 $check_commit_hook
 147 @wrapper_hooks
 148 $envsave
 149         newenviron[i++]="HOME=$ENV{HOME}";
 150         newenviron[i++]="PATH=$ENV{PATH}";
 151         newenviron[i++]="WRAPPED_OPTIONS=$configstring";
 152
 153 #ifdef __TINYC__
 154         /* old tcc versions do not support modifying environ directly */
 155         if (clearenv() != 0) {
 156                 perror("clearenv");
 157                 exit(1);
 158         }
 159         for (; i>0; i--)
 160                 putenv(newenviron[i-1]);
 161 #else
 162         newenviron[i]=NULL;
 163         environ=newenviron;
 164 #endif
 165
 166         if (setregid(getegid(), -1) != 0 &&
 167             setregid(getegid(), -1) != 0) {
 168                 perror("failed to drop real gid");
 169                 exit(1);
 170         }
 171         if (setreuid(geteuid(), -1) != 0 &&
 172             setreuid(geteuid(), -1) != 0) {
 173                 perror("failed to drop real uid");
 174                 exit(1);
 175         }
 176
 177 $pre_exec
 178
 179 $set_background_command
 180 #ifdef BACKGROUND_COMMAND
 181         if (lockfd != -1) {
 182                 close(lockfd);
 183         }
 184
 185         pid_t pid=fork();
 186         if (pid == -1) {
 187                 perror("fork");
 188                 exit(1);
 189         }
 190         else if (pid == 0) {
 191                 execl("$this", "$this", NULL);
 192                 perror("exec $this");
 193                 exit(1);
 194         }
 195         else {
 196                 waitpid(pid, NULL, 0);
 197
 198                 if (daemon(1, 0) == 0) {
 199                         system(BACKGROUND_COMMAND);
 200                         exit(0);
 201                 }
 202                 else {
 203                         perror("daemon");
 204                         exit(1);
 205                 }
 206         }
 207 #else
 208         execl("$this", "$this", NULL);
 209         perror("exec $this");
 210         exit(1);
 211 #endif
 212 }
 213 EOF
 214
 215         my @cc=exists $ENV{CC} ? possibly_foolish_untaint($ENV{CC}) : 'cc';
 216         push @cc, possibly_foolish_untaint($ENV{CFLAGS}) if exists $ENV{CFLAGS};
 217         if (system(@cc, "$wrapper.c", "-o", "$wrapper.new") != 0) {
 218                 #translators: The parameter is a C filename.
 219                 error(sprintf(gettext("failed to compile %s"), "$wrapper.c"));
 220         }
 221         unlink("$wrapper.c");
 222         if (defined $config{wrappergroup}) {
 223                 my $gid=(getgrnam($config{wrappergroup}))[2];
 224                 if (! defined $gid) {
 225                         error(sprintf("bad wrappergroup"));
 226                 }
 227                 if (! chown(-1, $gid, "$wrapper.new")) {
 228                         error("chown $wrapper.new: $!");
 229                 }
 230         }
 231         if (defined $config{wrappermode} &&
 232             ! chmod(oct($config{wrappermode}), "$wrapper.new")) {
 233                 error("chmod $wrapper.new: $!");
 234         }
 235         if (! rename("$wrapper.new", $wrapper)) {
 236                 error("rename $wrapper.new $wrapper: $!");
 237         }
 238         #translators: The parameter is a filename.
 239         printf(gettext("successfully generated %s"), $wrapper);
 240         print "\n";
 241 }
 242
 243 1