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#!/usr/bin/perl
use strict;
use Fcntl;
use POSIX qw(:unistd_h);
# arg: login_name
# returns the next available uid if login_name doesn't exist.
# otherwise returns (undef, <passwd fields for login_name>).
sub next_uid_if_not_exist {
my $login = shift;
my $min_uid = 1000;
my $max_uid = 60000;
if (open(LOGIN_DEF, "/etc/login.defs")) {
while (<LOGIN_DEF>) {
if (m/^\s*UID_MIN\s+(\d+)/) {
$min_uid = $1;
next;
}
if (m/^\s*UID_MAX\s+(\d+)/) {
$max_uid = $1;
next;
}
}
close LOGIN_DEF;
}
open(PASSWD, "/etc/passwd") or exit 1;
while (<PASSWD>) {
chomp;
my @passwd_fields = split /:/;
if ($passwd_fields[0] eq $login) {
close PASSWD;
return (undef, @passwd_fields);
}
if ($min_uid <= $passwd_fields[2]) {
next if ($passwd_fields[2] > $max_uid);
$min_uid = $passwd_fields[2] + 1;
next;
}
}
close PASSWD;
exit 2 if ($min_uid > $max_uid);
return ($min_uid);
}
# arg: login_name
# returns the corresponding line in shadow or undef if login_name doesn't
# exist.
sub get_shadow_line {
my $login = shift;
open(SHADOW, "/etc/shadow") or exit 3;
while (<SHADOW>) {
chomp;
if (m/^$login:/) {
close SHADOW;
return $_;
}
}
close SHADOW;
return undef;
}
# arg: login name
# removes the specified user from group/gshadow
sub remove_user_from_group {
my $user = shift;
my $sed_cmd = 'sed -i \'/^[^:]\+:/{'
. 's/:' . $user . '$/:/;'
. 's/:' . $user . ',/:/;'
. 's/,' . $user . ',/,/;'
. 's/,' . $user . '$//;}\'';
system("$sed_cmd /etc/group");
exit 1 if ($? >> 8);
system("$sed_cmd /etc/gshadow");
exit 1 if ($? >> 8);
}
# arg: login name
# adds the specified user to group/gshadow
sub add_user_to_group {
my $user = shift;
my $group = shift;
my $gcmd = 'grep -q -e \'^' . $group . ':.*[:,]' . $user . '\(,\|$\)\'';
my $ret = system("$gcmd /etc/group");
my $in_group = (($ret >> 8) == 0) ? 1 : 0;
$ret = system("$gcmd /etc/gshadow");
my $in_gshadow = (($ret >> 8) == 0) ? 1 : 0;
my $sed_cmd = 'sed -i \'/^' . $group . ':/{'
. 's/\([^:]\)$/\1,' . $user . '/;'
. 's/:$/:' . $user . '/;}\'';
if (!$in_group) {
system("$sed_cmd /etc/group");
exit 1 if ($? >> 8);
}
if (!$in_gshadow) {
system("$sed_cmd /etc/gshadow");
exit 1 if ($? >> 8);
}
}
my $user = shift;
my $full = shift;
my $encrypted = shift;
my $level = shift;
# emulate lckpwdf(3).
# difference: we only try to lock it once (non-blocking). lckpwdf will block
# for up to 15 seconds waiting for the lock.
# note that the lock is released when file is closed (e.g., exit), so no need
# for explicit unlock.
my $flock = pack "ssa20", F_WRLCK, SEEK_SET, "\0";
sysopen(PWDLCK, "/etc/.pwd.lock", O_WRONLY | O_CREAT, 0600) or exit 3;
fcntl(PWDLCK, F_SETLK, $flock) or exit 3;
if ($user eq "-d") {
$user = $full;
exit 4 if (!defined($user));
# check if user is using the system
my @pslines = `ps -U $user -u $user u`;
if ($#pslines != 0) {
# user is using the system
print STDERR "Delete failed: user \"$user\" is using the system\n";
exit 4;
}
my $ret = system("sed -i '/^$user:/d' /etc/passwd");
exit 5 if ($ret >> 8);
$ret = system("sed -i '/^$user:/d' /etc/shadow");
exit 6 if ($ret >> 8);
$ret = system("rm -rf /home/$user");
exit 7 if ($ret >> 8);
remove_user_from_group($user);
exit 0;
}
my %level_map = (
'admin' => [ 'users', 'quaggavty', 'vyattacfg', 'sudo', ],
'users' => [ 'users', 'quaggavty', ],
);
exit 4 if (!defined($user) || !defined($full) || !defined($encrypted)
|| !defined($level));
exit 4 if (!defined($level_map{$level}));
my $gref = $level_map{$level};
my @groups = @{$gref};
my $def_grp = $groups[0];
if ($user eq 'root') {
$def_grp = 'root';
}
# note that DEF_SHELL doesn't affect root since root is never "added"
my $DEF_SHELL = "/bin/vbash";
open(GRP, "/etc/group") or exit 5;
my $def_gid = undef;
while (<GRP>) {
my @group_fields = split /:/;
if ($group_fields[0] eq $def_grp) {
$def_gid = $group_fields[2];
last;
}
}
exit 6 if (!defined($def_gid));
my @vals = next_uid_if_not_exist($user);
my ($new_user, $passwd_line, $shadow_line) = (0, "", "");
if (defined($vals[0])) {
# add new user
$new_user = 1;
$passwd_line = "$user:x:$vals[0]:${def_gid}:$full:/home/$user:$DEF_SHELL";
my $sline = get_shadow_line($user);
exit 7 if (defined($sline));
my $seconds = `date +%s`;
my $days = int($seconds / 3600 / 24);
$shadow_line = "$user:$encrypted:$days:0:99999:7:::";
} else {
# modify existing user
shift @vals;
$vals[3] = $def_gid;
$vals[4] = $full;
$passwd_line = join(':', @vals);
my $sline = get_shadow_line($user);
exit 8 if (!defined($sline));
@vals = split /:/, $sline;
$vals[1] = $encrypted;
for (my $padding = (9 - $#vals - 1); $padding > 0; $padding--) {
push @vals, '';
}
$shadow_line = join(':', @vals);
}
my $ret = 0;
if (!$new_user) {
$ret = system("sed -i '/^$user:/d' /etc/passwd");
exit 9 if ($ret >> 8);
$ret = system("sed -i '/^$user:/d' /etc/shadow");
exit 10 if ($ret >> 8);
remove_user_from_group($user);
}
open(PASSWD, ">>/etc/passwd") or exit 11;
print PASSWD "$passwd_line\n";
close PASSWD;
open(SHADOW, ">>/etc/shadow") or exit 12;
print SHADOW "$shadow_line\n";
close SHADOW;
# root doesn't need to be added to group
if ($user ne 'root') {
foreach my $group (@groups) {
add_user_to_group($user, $group);
}
}
if (($new_user) && !(-e "/home/$user")) {
if (-d "/etc/skel") {
$ret = system("cp -a /etc/skel /home/$user");
exit 13 if ($ret >> 8);
$ret = system("chmod 755 /home/$user");
exit 14 if ($ret >> 8);
$ret = system("chown -R $user:$def_grp /home/$user");
exit 15 if ($ret >> 8);
} else {
$ret = system("mkdir -p /home/$user");
exit 16 if ($ret >> 8);
$ret = system("chmod 755 /home/$user");
exit 17 if ($ret >> 8);
}
}
exit 0;
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