1: #!/usr/bin/perl
2: # This script can be used as a "remote shell" command that is only
3: # capable of pretending to connect to "localhost". This is useful
4: # for testing or for running a local copy where the sender and the
5: # receiver needs to use different options (e.g. --fake-super). If
6: # we get -l USER, we try to become the USER, either directly (must
7: # be root) or by using "sudo -H -u USER" (requires --sudo option).
8:
9: use strict;
10: use warnings;
11: use Getopt::Long;
12: use English '-no_match_vars';
13:
14: &Getopt::Long::Configure('bundling');
15: &Getopt::Long::Configure('require_order');
16: GetOptions(
17: 'l=s' => \( my $login_name ),
18: '1|2|4|6|A|a|C|f|g|k|M|N|n|q|s|T|t|V|v|X|x|Y' => sub { }, # Ignore
19: 'b|c|D|e|F|i|L|m|O|o|p|R|S|w=s' => sub { }, # Ignore
20: 'no-cd' => \( my $no_chdir ),
21: 'sudo' => \( my $use_sudo ),
22: ) or &usage;
23: &usage unless @ARGV > 1;
24:
25: my $host = shift;
26: if ($host =~ s/^([^@]+)\@//) {
27: $login_name = $1;
28: }
29: if ($host ne 'localhost') {
30: die "lsh: unable to connect to host $host\n";
31: }
32:
33: my ($home_dir, @cmd);
34: if ($login_name) {
35: my ($uid, $gid);
36: if ($login_name =~ /\D/) {
37: $uid = getpwnam($login_name);
38: die "Unknown user: $login_name\n" unless defined $uid;
39: } else {
40: $uid = $login_name;
41: }
42: ($login_name, $gid, $home_dir) = (getpwuid($uid))[0,3,7];
43: if ($use_sudo) {
44: unshift @ARGV, "cd '$home_dir' &&" unless $no_chdir;
45: unshift @cmd, qw( sudo -H -u ), $login_name;
46: $no_chdir = 1;
47: } else {
48: my $groups = "$gid $gid";
49: while (my ($grgid, $grmembers) = (getgrent)[2,3]) {
50: if ($grgid != $gid && $grmembers =~ /(^|\s)\Q$login_name\E(\s|$)/o) {
51: $groups .= " $grgid";
52: }
53: }
54:
55: my ($ruid, $euid) = ($UID, $EUID);
56: $GID = $EGID = $groups;
57: $UID = $EUID = $uid;
58: die "Cannot set ruid: $! (use --sudo?)\n" if $UID == $ruid && $ruid != $uid;
59: die "Cannot set euid: $! (use --sudo?)\n" if $EUID == $euid && $euid != $uid;
60:
61: $ENV{USER} = $ENV{USERNAME} = $login_name;
62: $ENV{HOME} = $home_dir;
63: }
64: } else {
65: $home_dir = (getpwuid($UID))[7];
66: }
67:
68: unless ($no_chdir) {
69: chdir $home_dir or die "Unable to chdir to $home_dir: $!\n";
70: }
71:
72: push @cmd, '/bin/sh', '-c', "@ARGV";
73: exec @cmd;
74: die "Failed to exec: $!\n";
75:
76: sub usage
77: {
78: die <<EOT;
79: Usage: lsh [-l user] [--sudo] [--no-cd] localhost COMMAND [...]
80: EOT
81: }
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