aboutsummaryrefslogtreecommitdiff
path: root/IkiWiki/Wrapper.pm
blob: c39aa2ef7d678207ef86c938baef3f7af1933c30 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
#!/usr/bin/perl

package IkiWiki;

use warnings;
use strict;
use File::Spec;
use Data::Dumper;
use IkiWiki;

sub gen_wrappers () {
	debug(gettext("generating wrappers.."));
	my %origconfig=(%config);
	foreach my $wrapper (@{$config{wrappers}}) {
		%config=(%origconfig, %{$wrapper});
		$config{verbose}=$config{setupverbose}
			if exists $config{setupverbose};
		$config{syslog}=$config{setupsyslog}
			if exists $config{setupsyslog};
		delete @config{qw(setupsyslog setupverbose wrappers genwrappers rebuild)};
		checkconfig();
		if (! $config{cgi} && ! $config{post_commit} &&
		    ! $config{test_receive}) {
			$config{post_commit}=1;
		}
		gen_wrapper();
	}
	%config=(%origconfig);
}

sub gen_wrapper () {
	$config{srcdir}=File::Spec->rel2abs($config{srcdir});
	$config{destdir}=File::Spec->rel2abs($config{destdir});
	my $this=File::Spec->rel2abs($0);
	if (! -x $this) {
		error(sprintf(gettext("%s doesn't seem to be executable"), $this));
	}

	if ($config{setup}) {
		error(gettext("cannot create a wrapper that uses a setup file"));
	}
	my $wrapper=possibly_foolish_untaint($config{wrapper});
	if (! defined $wrapper || ! length $wrapper) {
		error(gettext("wrapper filename not specified"));
	}
	delete $config{wrapper};
	
	my @envsave;
	push @envsave, qw{REMOTE_ADDR QUERY_STRING REQUEST_METHOD REQUEST_URI
	               CONTENT_TYPE CONTENT_LENGTH GATEWAY_INTERFACE
		       HTTP_COOKIE REMOTE_USER HTTPS REDIRECT_STATUS
		       HTTP_HOST SERVER_PORT HTTPS HTTP_ACCEPT
		       REDIRECT_URL} if $config{cgi};
	my $envsave="";
	foreach my $var (@envsave) {
		$envsave.=<<"EOF";
	if ((s=getenv("$var")))
		addenv("$var", s);
EOF
	}
	
	my @wrapper_hooks;
	run_hooks(genwrapper => sub { push @wrapper_hooks, shift->() });

	my $check_commit_hook="";
	my $pre_exec="";
	if ($config{post_commit}) {
		# Optimise checking !commit_hook_enabled() , 
		# so that ikiwiki does not have to be started if the
		# hook is disabled.
		#
		# Note that perl's flock may be implemented using fcntl
		# or lockf on some systems. If so, and if there is no
		# interop between the locking systems, the true C flock will
		# always succeed, and this optimisation won't work.
		# The perl code will later correctly check the lock,
		# so the right thing will still happen, though without
		# the benefit of this optimisation.
		$check_commit_hook=<<"EOF";
	{
		int fd=open("$config{wikistatedir}/commitlock", O_CREAT | O_RDWR, 0666);
		if (fd != -1) {
			if (flock(fd, LOCK_SH | LOCK_NB) != 0)
				exit(0);
			close(fd);
		}
	}
EOF
	}
	elsif ($config{cgi}) {
		# Avoid more than one ikiwiki cgi running at a time by
		# taking a cgi lock. Since ikiwiki uses several MB of
		# memory, a pile up of processes could cause thrashing
		# otherwise. The fd of the lock is stored in
		# IKIWIKI_CGILOCK_FD so unlockwiki can close it.
		$pre_exec=<<"EOF";
	lockfd=open("$config{wikistatedir}/cgilock", O_CREAT | O_RDWR, 0666);
	if (lockfd != -1 && lockf(lockfd, F_LOCK, 0) == 0) {
		char *fd_s=malloc(8);
		sprintf(fd_s, "%i", lockfd);
		setenv("IKIWIKI_CGILOCK_FD", fd_s, 1);
	}
EOF
	}

	my $set_background_command='';
	if (defined $config{wrapper_background_command} &&
	    length $config{wrapper_background_command}) {
	    	my $background_command=delete $config{wrapper_background_command};
		$set_background_command=~s/"/\\"/g;
		$set_background_command='#define BACKGROUND_COMMAND "'.$background_command.'"';
	}

	$Data::Dumper::Indent=0; # no newlines
	my $configstring=Data::Dumper->Dump([\%config], ['*config']);
	$configstring=~s/\\/\\\\/g;
	$configstring=~s/"/\\"/g;
	$configstring=~s/\n/\\n/g;
	
	writefile(basename("$wrapper.c"), dirname($wrapper), <<"EOF");
/* A wrapper for ikiwiki, can be safely made suid. */
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/file.h>

extern char **environ;
char *newenviron[$#envsave+7];
int i=0;

void addenv(char *var, char *val) {
	char *s=malloc(strlen(var)+1+strlen(val)+1);
	if (!s)
		perror("malloc");
	sprintf(s, "%s=%s", var, val);
	newenviron[i++]=s;
}

int main (int argc, char **argv) {
	int lockfd=-1;
	char *s;

$check_commit_hook
@wrapper_hooks
$envsave
	newenviron[i++]="HOME=$ENV{HOME}";
	newenviron[i++]="PATH=$ENV{PATH}";
	newenviron[i++]="WRAPPED_OPTIONS=$configstring";

#ifdef __TINYC__
	/* old tcc versions do not support modifying environ directly */
	if (clearenv() != 0) {
		perror("clearenv");
		exit(1);
	}
	for (; i>0; i--)
		putenv(newenviron[i-1]);
#else
	newenviron[i]=NULL;
	environ=newenviron;
#endif

	if (setregid(getegid(), -1) != 0 &&
	    setregid(getegid(), -1) != 0) {
		perror("failed to drop real gid");
		exit(1);
	}
	if (setreuid(geteuid(), -1) != 0 &&
	    setreuid(geteuid(), -1) != 0) {
		perror("failed to drop real uid");
		exit(1);
	}

$pre_exec

$set_background_command
#ifdef BACKGROUND_COMMAND
	if (lockfd != -1) {
		close(lockfd);
	}

	pid_t pid=fork();
	if (pid == -1) {
		perror("fork");
		exit(1);
	}
	else if (pid == 0) {
		execl("$this", "$this", NULL);
		perror("exec $this");
		exit(1);		
	}
	else {
		waitpid(pid, NULL, 0);

		if (daemon(1, 0) == 0) {
			system(BACKGROUND_COMMAND);
			exit(0);
		}
		else {
			perror("daemon");
			exit(1);
		}
	}
#else
	execl("$this", "$this", NULL);
	perror("exec $this");
	exit(1);
#endif
}
EOF

	my @cc=exists $ENV{CC} ? possibly_foolish_untaint($ENV{CC}) : 'cc';
	push @cc, possibly_foolish_untaint($ENV{CFLAGS}) if exists $ENV{CFLAGS};
	if (system(@cc, "$wrapper.c", "-o", "$wrapper.new") != 0) {
		#translators: The parameter is a C filename.
		error(sprintf(gettext("failed to compile %s"), "$wrapper.c"));
	}
	unlink("$wrapper.c");
	if (defined $config{wrappergroup}) {
		my $gid=(getgrnam($config{wrappergroup}))[2];
		if (! defined $gid) {
			error(sprintf("bad wrappergroup"));
		}
		if (! chown(-1, $gid, "$wrapper.new")) {
			error("chown $wrapper.new: $!");
		}
	}
	if (defined $config{wrappermode} &&
	    ! chmod(oct($config{wrappermode}), "$wrapper.new")) {
		error("chmod $wrapper.new: $!");
	}
	if (! rename("$wrapper.new", $wrapper)) {
		error("rename $wrapper.new $wrapper: $!");
	}
	#translators: The parameter is a filename.
	debug(sprintf(gettext("successfully generated %s"), $wrapper));
}

1