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shadow/lib/pwauth.c

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/*
* Copyright 1992 - 1994, Julianne Frances Haugh
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Julianne F. Haugh nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY JULIE HAUGH AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL JULIE HAUGH OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <config.h>
#include "rcsid.h"
RCSID("$Id: pwauth.c,v 1.11 2000/08/26 18:27:17 marekm Exp $")
#include <sys/types.h>
#include <signal.h>
#include <fcntl.h>
#include <stdio.h>
#include <errno.h>
#include "prototypes.h"
#include "defines.h"
#include "pwauth.h"
#include "getdef.h"
#ifdef SKEY
#include <skey.h>
#endif
#ifdef OPIE
#include <opie.h>
#endif
#ifdef __linux__ /* standard password prompt by default */
static const char *PROMPT = gettext_noop("Password: ");
#else
static const char *PROMPT = gettext_noop("%s's Password: ");
#endif
extern char *getpass();
extern char *getpass_with_echo();
#ifdef AUTH_METHODS
/*
* Look-up table for bound-in methods. Put the name that the
* method is known by in the password field as "name" and a
* pointer to the function
*/
struct method {
char *name;
int (*func)(const char *, int, const char *);
};
#ifdef PAD_AUTH
int pad_auth();
#endif
static struct method methods[] = {
#ifdef PAD_AUTH
{ "pad", pad_auth },
#endif
{ "", 0 }
};
#endif /* AUTH_METHODS */
int wipe_clear_pass = 1;
char *clear_pass = NULL;
/*
* _old_auth - perform getpass/crypt authentication
*
* _old_auth gets the user's cleartext password and encrypts it
* using the salt in the encrypted password. The results are
* compared.
*/
static int
_old_auth(const char *cipher, const char *user, int reason, const char *input)
{
char prompt[1024];
char *clear = NULL;
const char *cp;
int retval;
#ifdef SKEY
int use_skey = 0;
char challenge_info[40];
struct skey skey;
#endif
#ifdef OPIE
int use_opie = 0;
char o_challenge_info[OPIE_CHALLENGE_MAX + 1];
struct opie opie;
/*
* This implementation is based almost entirely on the SKEY code
* above. Thus the opie struct is called skey, etc. I am unaware
* if the system works at the same time, but I cannot imagine why
* anyone would want to do this....
* -- A.R.
* Mod: 5/14/98 A.R.
* Made the OPIE code separate from the S/Key code. Now
* (conceivably) both can be compiled in and function apart from
* one another (assuming a sysadmin really wants to maintain OPIE
* and an S/Key databases....).
*
* Also cleaned up the code a bit. Will be adding second-prompt
* support (the traditional Echo-on S/Key/OPIE-only prompts to let
* the users see the one-time passwords they are typing/pasting
* in....
* -- A.R.
*/
#endif
/*
* There are programs for adding and deleting authentication data.
*/
if (reason == PW_ADD || reason == PW_DELETE)
return 0;
/*
* There are even programs for changing the user name ...
*/
if (reason == PW_CHANGE && input != (char *) 0)
return 0;
/*
* WARNING:
*
* When we change a password and we are root, we don't prompt.
* This is so root can change any password without having to
* know it. This is a policy decision that might have to be
* revisited.
*/
if (reason == PW_CHANGE && getuid () == 0)
return 0;
/*
* WARNING:
*
* When we are logging in a user with no ciphertext password,
* we don't prompt for the password or anything. In reality
* the user could just hit <ENTER>, so it doesn't really
* matter.
*/
if (cipher == (char *) 0 || *cipher == '\0')
return 0;
#ifdef SKEY
/*
* If the user has an S/KEY entry show them the pertinent info
* and then we can try validating the created cyphertext and the SKEY.
* If there is no SKEY information we default to not using SKEY.
*/
if (skeychallenge (&skey, user, challenge_info) == 0)
use_skey = 1;
#endif
#ifdef OPIE
/*
* Ditto above, for OPIE passwords.
* -- AR
*/
o_challenge_info[0] = '\0';
if (opiechallenge(&opie, user, o_challenge_info) == 0)
use_opie = 1;
if (use_opie == 0)
opieverify(&opie, (char *)NULL);
/*
* This call to opieverify is necessary within OPIE's interface:
* Every call to opiechallenge(), which checks to see if the user
* has an OPIE password, and if so get the challenge, must be
* accompanied by exactly one call to opieverify, which clears
* any outstanding locks, and otherwise cleans up.
* -- AR
*/
#endif
/*
* Prompt for the password as required. FTPD and REXECD both
* get the cleartext password for us.
*/
if (reason != PW_FTP && reason != PW_REXEC && !input) {
if (! (cp = getdef_str ("LOGIN_STRING")))
cp = _(PROMPT);
#ifdef SKEY
if (use_skey)
printf ("[%s]\n", challenge_info);
#endif
#ifdef OPIE
if (use_opie)
printf("[ %s ]\n", o_challenge_info);
#endif
snprintf(prompt, sizeof prompt, cp, user);
clear = getpass(prompt);
if (!clear) {
static char c[1];
c[0] = '\0';
clear = c;
}
input = clear;
}
/*
* Convert the cleartext password into a ciphertext string.
* If the two match, the return value will be zero, which is
* SUCCESS. Otherwise we see if SKEY is being used and check
* the results there as well.
*/
retval = strcmp(pw_encrypt(input, cipher), cipher);
#ifdef OPIE
/*
* This is required because using OPIE, opieverify() MUST be called
* opiechallenge() above even if OPIE isn't being used in this case,
* so locks get released, etc.
* -- AR
*/
if ((retval == 0) && use_opie)
opieverify(&opie, (char *)NULL);
#endif
#if (defined(SKEY) || defined(OPIE))
/*
* If (1) The password fails to match, and
* (2) The password is empty and
* (3) We are using OPIE or S/Key, then
* ...Re-prompt, with echo on.
* -- AR 8/22/1999
*/
if (retval && !input[0] &&
(0
#ifdef SKEY
|| use_skey
#endif
#ifdef OPIE
|| use_opie
#endif
)) {
strncat(prompt, _("(Echo on) "),
(sizeof(prompt) - strlen(prompt)));
clear = getpass_with_echo(prompt);
if (!clear) {
static char c[1];
c[0] = '\0';
clear = c;
}
input = clear;
}
#endif
#ifdef SKEY
if (retval && use_skey) {
int passcheck = -1;
#if 0 /* some skey libs don't have skey_passcheck. --marekm */
passcheck = skey_passcheck(user, input);
#else
if (skeyverify(&skey, input) == 0)
passcheck = skey.n;
#endif /* if 0 */
if (passcheck > 0)
retval = 0;
}
#endif
#ifdef OPIE
if (retval && use_opie) {
if (opieverify(&opie, input) == 0)
retval = 0;
}
#endif /* OPIE */
/*
* Things like RADIUS authentication may need the password -
* if the external variable wipe_clear_pass is zero, we will
* not wipe it (the caller should wipe clear_pass when it is
* no longer needed). --marekm
*/
clear_pass = clear;
if (wipe_clear_pass && clear && *clear)
strzero(clear);
return retval;
}
#ifdef AUTH_METHODS
/*
* _pw_auth - perform alternate password authentication
*
* pw_auth executes the alternate password authentication method
* described in the user's password entry. _pw_auth does the real
* work, pw_auth splits the authentication string into individual
* command names.
*/
static int
_pw_auth(const char *command, const char *user, int reason, const char *input)
{
RETSIGTYPE (*sigint)();
RETSIGTYPE (*sigquit)();
#ifdef SIGTSTP
RETSIGTYPE (*sigtstp)();
#endif
int pid;
int status;
int i;
char * const argv[5];
int argc = 0;
int pipes[2];
char *empty_env = NULL;
int use_pipe;
/*
* Start with a quick sanity check. ALL command names must
* be fully-qualified path names.
*/
if (command[0] != '/')
return -1;
/*
* Set the keyboard signals to be ignored. When the user kills
* the child we don't want the parent dying as well.
*/
sigint = signal (SIGINT, SIG_IGN);
sigquit = signal (SIGQUIT, SIG_IGN);
#ifdef SIGTSTP
sigtstp = signal (SIGTSTP, SIG_IGN);
#endif
/*
* FTP and REXEC reasons don't give the program direct access
* to the user. This means that the program can only get input
* from this function. So we set up a pipe for that purpose.
*/
use_pipe = (reason == PW_FTP || reason == PW_REXEC);
if (use_pipe)
if (pipe (pipes))
return -1;
/*
* The program will be forked off with the parent process waiting
* on the child to tell it how successful it was.
*/
switch (pid = fork ()) {
/*
* The fork() failed completely. Clean up as needed and
* return to the caller.
*/
case -1:
if (use_pipe) {
close (pipes[0]);
close (pipes[1]);
}
return -1;
case 0:
/*
* Let the child catch the SIGINT and SIGQUIT
* signals. The parent, however, will continue
* to ignore them.
*/
signal (SIGINT, SIG_DFL);
signal (SIGQUIT, SIG_DFL);
/*
* Set up the command line. The first argument is
* the name of the command being executed. The
* second is the command line option for the reason,
* and the third is the user name.
*/
argv[argc++] = command;
switch (reason) {
case PW_SU: argv[argc++] = "-s"; break;
case PW_LOGIN: argv[argc++] = "-l"; break;
case PW_ADD: argv[argc++] = "-a"; break;
case PW_CHANGE: argv[argc++] = "-c"; break;
case PW_DELETE: argv[argc++] = "-d"; break;
case PW_TELNET: argv[argc++] = "-t"; break;
case PW_RLOGIN: argv[argc++] = "-r"; break;
case PW_FTP: argv[argc++] = "-f"; break;
case PW_REXEC: argv[argc++] = "-x"; break;
}
if (reason == PW_CHANGE && input)
argv[argc++] = input;
argv[argc++] = user;
argv[argc] = (char *) 0;
/*
* The FTP and REXEC reasons use a pipe to communicate
* with the parent. The other standard I/O descriptors
* are closed and re-opened as /dev/null.
*/
if (use_pipe) {
close (0);
close (1);
close (2);
if (dup (pipes[0]) != 0)
exit (1);
close (pipes[0]);
close (pipes[1]);
if (open ("/dev/null", O_WRONLY) != 1)
exit (1);
if (open ("/dev/null", O_WRONLY) != 2)
exit (1);
}
/*
* Now we execute the command directly.
* Do it with empty environment for safety. --marekm
*/
execve(command, argv, &empty_env);
_exit((errno == ENOENT) ? 127 : 126);
/*NOTREACHED*/
default:
/*
* FTP and REXEC cause a single line of text to be
* sent to the child over a pipe that was set up
* earlier.
*/
if (use_pipe) {
close (pipes[0]);
if (input)
write (pipes[1], input, strlen (input));
write (pipes[1], "\n", 1);
close (pipes[1]);
}
/*
* Wait on the child to die. When it does you will
* get the exit status and use that to determine if
* the authentication program was successful.
*/
while ((i = wait (&status)) != pid && i != -1)
;
/*
* Re-set the signals to their earlier values.
*/
signal (SIGINT, sigint);
signal (SIGQUIT, sigquit);
#ifdef SIGTSTP
signal (SIGTSTP, sigtstp);
#endif
/*
* Make sure we found the right process!
*/
if (i == -1)
return -1;
if (status == 0)
return 0;
else
return -1;
}
/*NOTREACHED*/
}
/*
* _builtin_auth - lookup routine in table and execute
*/
static int
_builtin_auth(const char *command, const char *user, int reason, const char *input)
{
int i;
/*
* Scan the table, looking for a match. If we fall off
* the end, it must mean that this method isn't supported,
* so we fail the authentication.
*/
for (i = 0;methods[i].name[0];i++) {
if (! strcmp (command, methods[i].name))
break;
}
if (methods[i].name[0] == '\0')
return -1;
/*
* Call the pointed to function with the other three
* arguments.
*/
return (methods[i].func) (user, reason, input);
}
#endif /* AUTH_METHODS */
/*
* This function does the real work. It splits the list of program names
* up into individual programs and executes them one at a time.
*/
int
pw_auth(const char *command, const char *user, int reason, const char *input)
{
#ifdef AUTH_METHODS
char buf[256];
char *cmd, *end;
int rc;
/*
* Quick little sanity check ...
*/
if (strlen (command) >= sizeof buf)
return -1;
strcpy(buf, command); /* safe (because of the above check) --marekm */
/*
* Find each command and make sure it is NUL-terminated. Then
* invoke _pw_auth to actually run the program. The first
* failing program ends the whole mess.
*/
for (cmd = buf;cmd;cmd = end) {
if ((end = strchr (cmd, ';')))
*end++ = '\0';
if (cmd[0] != '@')
rc = _old_auth (cmd, user, reason, input);
else if (cmd[1] == '/')
rc = _pw_auth (cmd + 1, user, reason, input);
else
rc = _builtin_auth (cmd + 1, user, reason, input);
if (rc)
return -1;
}
return 0;
#else
return _old_auth(command, user, reason, input);
#endif
}
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