Annotation of loncom/lcuseradd, revision 1.9
1.1 harris41 1: #!/usr/bin/perl
2: #
3: # lcuseradd
4: #
5: # Scott Harrison
6: # October 27, 2000
7:
8: use strict;
9:
10: # This script is a setuid script that should
11: # be run by user 'www'. It creates a /home/USERNAME directory
12: # as well as a /home/USERNAME/public_html directory.
13: # It adds user entries to
14: # /etc/passwd and /etc/groups.
1.2 harris41 15: # Passwords are set with lcpasswd.
16: # www becomes a member of this user group.
1.1 harris41 17:
18: # Standard input usage
19: # First line is USERNAME
20: # Second line is PASSWORD
1.3 harris41 21: # Third line is PASSWORD
1.1 harris41 22:
1.7 harris41 23: # Valid passwords must consist of the
24: # ascii characters within the inclusive
25: # range of 0x20 (32) to 0x7E (126).
26: # These characters are:
27: # SPACE and
28: # !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNO
29: # PQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~
30:
31: # Valid user names must consist of ascii
32: # characters that are alphabetical characters
33: # (A-Z,a-z), numeric (0-9), or the underscore
34: # mark (_). (Essentially, the perl regex \w).
35:
1.3 harris41 36: # Command-line arguments [USERNAME] [PASSWORD] [PASSWORD]
1.1 harris41 37: # Yes, but be very careful here (don't pass shell commands)
38: # and this is only supported to allow perl-system calls.
39:
1.4 harris41 40: # Usage within code
41: #
42: # $exitcode=system("/home/httpd/perl/lcuseradd","NAME","PASSWORD1","PASSWORD2")/256;
43: # print "uh-oh" if $exitcode;
44:
45: # These are the exit codes.
46:
1.1 harris41 47: # Security
48: $ENV{'PATH'}=""; # Nullify path information.
49: $ENV{'BASH_ENV'}=""; # Nullify shell environment information.
1.2 harris41 50:
1.4 harris41 51: # Do not print error messages if there are command-line arguments
52: my $noprint=0;
53: if (@ARGV) {
54: $noprint=1;
55: }
56:
57: # Read in /etc/passwd, and make sure this process is running from user=www
58: open (IN, "</etc/passwd");
59: my @lines=<IN>;
60: close IN;
61: my $wwwid;
62: for my $l (@lines) {
63: chop $l;
64: my @F=split(/\:/,$l);
65: if ($F[0] eq 'www') {$wwwid=$F[2];}
66: }
67: if ($wwwid!=$<) {
68: print("User ID mismatch. This program must be run as user 'www'\n") unless $noprint;
69: exit 1;
70: }
71: &disable_root_capability;
72:
73: # Handle case of another lcpasswd process
74: unless (&try_to_lock("/tmp/lock_lcpasswd")) {
75: print "Error. Too many other simultaneous password change requests being made.\n" unless $noprint;
76: exit 4;
77: }
78:
79: # Gather input. Should be 3 values (user name, password 1, password 2).
80: my @input;
1.5 harris41 81: if (@ARGV==3) {
1.4 harris41 82: @input=@ARGV;
83: }
84: elsif (@ARGV) {
85: print("Error. This program needs 3 command-line arguments (username, password 1, password 2).\n") unless $noprint;
86: unlink('/tmp/lock_lcpasswd');
87: exit 2;
88: }
89: else {
90: @input=<>;
1.5 harris41 91: if (@input!=3) {
1.4 harris41 92: print("Error. Three lines should be entered into standard input.\n") unless $noprint;
93: unlink('/tmp/lock_lcpasswd');
94: exit 3;
95: }
96: map {chop} @input;
97: }
98:
99: my ($username,$password1,$password2)=@input;
100: $username=~/^(\w+)$/;
101: my $safeusername=$1;
1.8 harris41 102: if ($username ne $safeusername) {
103: print "Error. The user name specified has invalid characters.\n";
104: unlink('/tmp/lock_lcpasswd');
105: exit 9;
106: }
107: my $pbad=0;
1.9 ! harris41 108: map {if ((ord($_)<32)||(ord($_)>126)){$pbad=1;}} (split(//,$password1));
! 109: map {if ((ord($_)<32)||(ord($_)>126)){$pbad=1;}} (split(//,$password2));
1.8 harris41 110: if ($pbad) {
111: print "Error. A password entry had an invalid character.\n";
112: unlink('/tmp/lock_lcpasswd');
113: exit 10;
114: }
1.5 harris41 115:
1.7 harris41 116: # Only add user if we can create a brand new home directory (/home/username).
117: if (-e "/home/$safeusername") {
118: print "Error. User already exists.\n" unless $noprint;
119: unlink('/tmp/lock_lcpasswd');
120: exit 8;
121: }
122:
123: # Only add user if the two password arguments match.
1.5 harris41 124: if ($password1 ne $password2) {
1.6 harris41 125: print "Error. Password mismatch.\n" unless $noprint;
1.5 harris41 126: unlink('/tmp/lock_lcpasswd');
127: exit 7;
128: }
1.4 harris41 129:
130: &enable_root_capability;
131:
1.3 harris41 132: # Add user entry to /etc/passwd and /etc/groups in such
133: # a way that www is a member of the user-specific group
134:
1.5 harris41 135: if (system('/usr/sbin/useradd','-c','LON-CAPA user',$safeusername)) {
1.6 harris41 136: print "Error. Something went wrong with the addition of user \"$safeusername\".\n" unless $noprint;
1.4 harris41 137: unlink('/tmp/lock_lcpasswd');
138: exit 5;
139: }
1.7 harris41 140:
141: # Make www a member of that user group.
1.5 harris41 142: if (system('/usr/sbin/usermod','-G',$safeusername,'www')) {
1.6 harris41 143: print "Error. Could not make www a member of the group \"$safeusername\".\n" unless $noprint;
1.5 harris41 144: unlink('/tmp/lock_lcpasswd');
145: exit 6;
146: }
147:
148: # Set password with lcpasswd-style algorithm (which creates smbpasswd entry).
149: # I cannot place a direct shell call to lcpasswd since I have to allow
150: # for crazy characters in the password, and the setuid environment of perl
151: # requires me to make everything safe.
1.7 harris41 152:
1.8 harris41 153: # Grab the line corresponding to username
1.9 ! harris41 154: open (IN, "</etc/passwd");
! 155: @lines=<IN>;
! 156: close IN;
1.8 harris41 157: my ($userid,$useroldcryptpwd);
158: my @F; my @U;
159: for my $l (@lines) {
160: @F=split(/\:/,$l);
161: if ($F[0] eq $username) {($userid,$useroldcryptpwd)=($F[2],$F[1]); @U=@F;}
162: }
1.5 harris41 163:
1.8 harris41 164: # Verify existence of user
165: if (!defined($userid)) {
166: print "Error. User $username does not exist.\n" unless $noprint;
167: unlink('/tmp/lock_lcpasswd');
168: exit 5;
169: }
1.2 harris41 170:
1.8 harris41 171: # Construct new password entry (random salt)
172: my $newcryptpwd=crypt($newpwd,(join '', ('.', '/', 0..9, 'A'..'Z', 'a'..'z')[rand 64, rand 64]));
173: $U[1]=$newcryptpwd;
174: my $userline=join(':',@U);
175: my $rootid=&enable_root_capability;
176: if ($rootid!=0) {
177: print "Error. Root was not successfully enabled.\n" unless $noprint;
178: unlink('/tmp/lock_lcpasswd');
179: exit 7;
180: }
181: open PASSWORDFILE, '>/etc/passwd' or (print("Error. Cannot open /etc/passwd.\n") && unlink('/tmp/lock_lcpasswd') && exit(8));
182: for my $l (@lines) {
183: @F=split(/\:/,$l);
184: if ($F[0] eq $username) {print PASSWORDFILE "$userline\n";}
185: else {print PASSWORDFILE "$l\n";}
186: }
187: close PASSWORDFILE;
188:
189: ($>,$<)=(0,0); # fool smbpasswd here to think this is not a setuid environment
190: unless (-e '/etc/smbpasswd') {
191: open (OUT,'>/etc/smbpasswd'); close OUT;
192: }
193: my $smbexist=0;
194: open (IN, '</etc/smbpasswd');
195: my @lines=<IN>;
196: close IN;
197: for my $l (@lines) {
198: chop $l;
199: my @F=split(/\:/,$l);
200: if ($F[0] eq $username) {$smbexist=1;}
201: }
202: unless ($smbexist) {
203: open(OUT,'>>/etc/smbpasswd');
204: print OUT join(':',($safeusername,$userid,'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX:XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX','','/home/'.$safeusername,'/bin/bash')) . "\n";
205: close OUT;
206: }
207: open(OUT,"|/usr/bin/smbpasswd -s $safeusername>/dev/null");
208: print OUT $newpwd; print OUT "\n";
209: print OUT $newpwd; print OUT "\n";
210: close OUT;
211: $<=$wwwid; # unfool the program
212:
213: # Make final modifications to the user directory.
214: # Add a public_html file with a stand-in index.html file.
215:
1.9 ! harris41 216: system('/bin/chmod','-R','0640',"/home/$safeusername");
! 217: system('/bin/chmod','0750',"/home/$safeusername");
1.8 harris41 218: mkdir "/home/$safeusername/public_html",0750;
219: open OUT,">/home/$safeusername/public_html";
220: print OUT<<END;
221: <HTML>
222: <HEAD>
223: <TITLE>$safeusername</TITLE>
224: </HEAD>
225: <BODY>
226: <H1>$safeusername</H1>
227: <P>
228: Learning Online Network
229: </P>
230: <P>
231: This area provides for:
232: </P>
233: <UL>
234: <LI>resource construction
235: <LI>resource publication
236: <LI>record-keeping
237: </UL>
238: </BODY>
239: </HTML>
240: END
241: close OUT;
242:
243: &disable_root_capability;
244: unlink('/tmp/lock_lcpasswd');
245: exit 0;
1.1 harris41 246:
1.5 harris41 247: # ----------------------------------------------------------- have setuid script run as root
248: sub enable_root_capability {
249: if ($wwwid==$>) {
250: ($<,$>)=($>,$<);
251: ($(,$))=($),$();
252: }
253: else {
254: # root capability is already enabled
255: }
256: return $>;
257: }
258:
259: # ----------------------------------------------------------- have setuid script run as www
260: sub disable_root_capability {
261: if ($wwwid==$<) {
262: ($<,$>)=($>,$<);
263: ($(,$))=($),$();
264: }
265: else {
266: # root capability is already disabled
267: }
268: }
269:
270: # ----------------------------------- make sure that another lcpasswd process isn't running
271: sub try_to_lock {
272: my ($lockfile)=@_;
273: my $currentpid;
274: my $lastpid;
275: # Do not manipulate lock file as root
276: if ($>==0) {
277: return 0;
278: }
279: # Try to generate lock file.
280: # Wait 3 seconds. If same process id is in
281: # lock file, then assume lock file is stale, and
282: # go ahead. If process id's fluctuate, try
283: # for a maximum of 10 times.
284: for (0..10) {
285: if (-e $lockfile) {
286: open(LOCK,"<$lockfile");
287: $currentpid=<LOCK>;
288: close LOCK;
289: if ($currentpid==$lastpid) {
290: last;
291: }
292: sleep 3;
293: $lastpid=$currentpid;
294: }
295: else {
296: last;
297: }
298: if ($_==10) {
299: return 0;
300: }
301: }
302: open(LOCK,">$lockfile");
303: print LOCK $$;
304: close LOCK;
305: return 1;
306: }
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