1#!/usr/bin/perl
2# Name: /usr/local/bin/rrsync (should also have a symlink in /usr/bin)
3# Purpose: Restricts rsync to subdirectory declared in .ssh/authorized_keys
4# Author: Joe Smith <js-cgi@inwap.com> 30-Sep-2004
5# Modified by: Wayne Davison <wayned@samba.org>
6use strict;
7
8use Socket;
9use Cwd 'abs_path';
10use File::Glob ':glob';
11
12# You may configure these values to your liking.  See also the section
13# of options if you want to disable any options that rsync accepts.
14use constant RSYNC => '/usr/bin/rsync';
15use constant LOGFILE => 'rrsync.log';
16
17my $Usage = <<EOM;
18Use 'command="$0 [-ro] SUBDIR"'
19	in front of lines in $ENV{HOME}/.ssh/authorized_keys
20EOM
21
22our $ro = (@ARGV && $ARGV[0] eq '-ro') ? shift : '';	# -ro = Read-Only
23our $subdir = shift;
24die "$0: No subdirectory specified\n$Usage" unless defined $subdir;
25$subdir = abs_path($subdir);
26die "$0: Restricted directory does not exist!\n" if $subdir ne '/' && !-d $subdir;
27
28# The client uses "rsync -av -e ssh src/ server:dir/", and sshd on the server
29# executes this program when .ssh/authorized_keys has 'command="..."'.
30# For example:
31# command="rrsync logs/client" ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAIEAzGhEeNlPr...
32# command="rrsync -ro results" ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAIEAmkHG1WCjC...
33#
34# Format of the envrionment variables set by sshd:
35# SSH_ORIGINAL_COMMAND=rsync --server          -vlogDtpr --partial . ARG # push
36# SSH_ORIGINAL_COMMAND=rsync --server --sender -vlogDtpr --partial . ARGS # pull
37# SSH_CONNECTION=client_addr client_port server_port
38
39my $command = $ENV{SSH_ORIGINAL_COMMAND};
40die "$0: Not invoked via sshd\n$Usage"	unless defined $command;
41die "$0: SSH_ORIGINAL_COMMAND='$command' is not rsync\n" unless $command =~ s/^rsync\s+//;
42our $am_sender = $command =~ /^--server\s+--sender\s/; # Restrictive on purpose!
43die "$0 -ro: sending to read-only server not allowed\n" if $ro && !$am_sender;
44
45### START of options data produced by the cull_options script. ###
46
47# These options are the only options that rsync might send to the server,
48# and only in the option format that the stock rsync produces.
49
50# To disable a short-named option, add its letter to this string:
51our $short_disabled = '';
52
53our $short_no_arg = 'CDEHIKLORSWbcdgklmnoprtuvxz'; # DO NOT REMOVE ANY
54our $short_with_num = 'B'; # DO NOT REMOVE ANY
55
56# To disable a long-named option, change its value to a -1.  The values mean:
57# 0 = the option has no arg; 1 = the arg doesn't need any checking; 2 = only
58# check the arg when receiving; and 3 = always check the arg.
59our %long_opt = (
60  'append' => 0,
61  'backup-dir' => 2,
62  'bwlimit' => 1,
63  'checksum-seed' => 1,
64  'compare-dest' => 2,
65  'compress-level' => 1,
66  'copy-dest' => 2,
67  'copy-unsafe-links' => 0,
68  'daemon' => 0,
69  'delay-updates' => 0,
70  'delete' => 0,
71  'delete-after' => 0,
72  'delete-before' => 0,
73  'delete-during' => 0,
74  'delete-excluded' => 0,
75  'existing' => 0,
76  'files-from' => 3,
77  'force' => 0,
78  'from0' => 0,
79  'fuzzy' => 0,
80  'ignore-errors' => 0,
81  'ignore-existing' => 0,
82  'inplace' => 0,
83  'link-dest' => 2,
84  'list-only' => 0,
85  'log-format' => 1,
86  'max-delete' => 1,
87  'max-size' => 1,
88  'min-size' => 1,
89  'modify-window' => 1,
90  'no-implied-dirs' => 0,
91  'no-r' => 0,
92  'no-relative' => 0,
93  'no-specials' => 0,
94  'numeric-ids' => 0,
95  'only-write-batch' => 1,
96  'partial' => 0,
97  'partial-dir' => 2,
98  'remove-sent-files' => $ro ? -1 : 0,
99  'remove-source-files' => $ro ? -1 : 0,
100  'safe-links' => 0,
101  'sender' => 0,
102  'server' => 0,
103  'size-only' => 0,
104  'specials' => 0,
105  'suffix' => 1,
106  'super' => 0,
107  'temp-dir' => 2,
108  'timeout' => 1,
109);
110
111### END of options data produced by the cull_options script. ###
112
113if ($short_disabled ne '') {
114    $short_no_arg =~ s/[$short_disabled]//go;
115    $short_with_num =~ s/[$short_disabled]//go;
116}
117$short_no_arg = "[$short_no_arg]" if length($short_no_arg) > 1;
118$short_with_num = "[$short_with_num]" if length($short_with_num) > 1;
119
120my $write_log = -f LOGFILE && open(LOG, '>>', LOGFILE);
121
122chdir($subdir) or die "$0: Unable to chdir to restricted dir: $!\n";
123
124my(@opts, @args);
125my $in_options = 1;
126my $last_opt = '';
127my $check_type;
128while ($command =~ /((?:[^\s\\]+|\\.[^\s\\]*)+)/g) {
129  $_ = $1;
130  if ($check_type) {
131    push(@opts, check_arg($last_opt, $_, $check_type));
132    $check_type = 0;
133  } elsif ($in_options) {
134    push(@opts, $_);
135    if ($_ eq '.') {
136      $in_options = 0;
137    } else {
138      next if /^-$short_no_arg+$/o || /^-$short_with_num\d+$/o;
139
140      my($opt,$arg) = /^--([^=]+)(?:=(.*))?$/;
141      my $disabled;
142      if (defined $opt) {
143	my $ct = $long_opt{$opt};
144	last unless defined $ct;
145	next if $ct == 0;
146	if ($ct > 0) {
147	  if (!defined $arg) {
148	    $check_type = $ct;
149	    $last_opt = $opt;
150	    next;
151	  }
152	  $arg = check_arg($opt, $arg, $ct);
153	  $opts[-1] =~ s/=.*/=$arg/;
154	  next;
155	}
156	$disabled = 1;
157	$opt = "--$opt";
158      } elsif ($short_disabled ne '') {
159	$disabled = /^-$short_no_arg*([$short_disabled])/o;
160	$opt = "-$1";
161      }
162
163      last unless $disabled; # Generate generic failure
164      die "$0: option $opt has been disabled on this server.\n";
165    }
166  } else {
167    if ($subdir ne '/') {
168      # Validate args to ensure they don't try to leave our restricted dir.
169      s#//+#/#g;
170      s#^/##;
171      s#^$#.#;
172      die "Do not use .. in any path!\n" if m#(^|/)\\?\.\\?\.(\\?/|$)#;
173    }
174    push(@args, bsd_glob($_, GLOB_LIMIT|GLOB_NOCHECK|GLOB_BRACE|GLOB_QUOTE));
175  }
176}
177die "$0: invalid rsync-command syntax or options\n" if $in_options;
178
179@args = ( '.' ) if !@args;
180
181if ($write_log) {
182  my ($mm,$hh) = (localtime)[1,2];
183  my $host = $ENV{SSH_CONNECTION} || 'unknown';
184  $host =~ s/ .*//; # Keep only the client's IP addr
185  $host =~ s/^::ffff://;
186  $host = gethostbyaddr(inet_aton($host),AF_INET) || $host;
187  printf LOG "%02d:%02d %-13s [%s]\n", $hh, $mm, $host, "@opts @args";
188  close LOG;
189}
190
191# Note: This assumes that the rsync protocol will not be maliciously hijacked.
192exec(RSYNC, @opts, @args) or die "exec(rsync @opts @args) failed: $? $!";
193
194sub check_arg
195{
196  my($opt, $arg, $type) = @_;
197  $arg =~ s/\\(.)/$1/g;
198  if ($subdir ne '/' && ($type == 3 || ($type == 2 && !$am_sender))) {
199    $arg =~ s#//#/#g;
200    die "Do not use .. in --$opt; anchor the path at the root of your restricted dir.\n"
201      if $arg =~ m#(^|/)\.\.(/|$)#;
202    $arg =~ s#^/#$subdir/#;
203  }
204  $arg;
205}
206