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81d5c71a4b
yubico-pam/pam_yubico.c
Simon Josefsson 81d5c71a4b Fix crash on memory errors.
2009-03-24 15:21:09 +00:00

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/* Written by Simon Josefsson <simon@yubico.com>.
* Copyright (c) 2006, 2007, 2008, 2009 Yubico AB
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * 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.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 THE COPYRIGHT
* OWNER 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 <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <ctype.h>
/* Libtool defines PIC for shared objects */
#ifndef PIC
#define PAM_STATIC
#endif
/* These #defines must be present according to PAM documentation. */
#define PAM_SM_AUTH
#define PAM_SM_ACCOUNT
#define PAM_SM_SESSION
#define PAM_SM_PASSWORD
#ifdef HAVE_SECURITY_PAM_APPL_H
#include <security/pam_appl.h>
#endif
#ifdef HAVE_SECURITY_PAM_MODULES_H
#include <security/pam_modules.h>
#endif
#if defined(DEBUG_PAM)
# if defined(HAVE_SECURITY__PAM_MACROS_H)
# define DEBUG
# include <security/_pam_macros.h>
# else
# define D(x) do { \
printf ("debug: %s:%d (%s): ", __FILE__, __LINE__, __FUNCTION__); \
printf x; \
printf ("\n"); \
} while (0)
# endif
#endif
#include <libykclient.h>
#ifdef HAVE_LIBLDAP
#include <ldap.h>
#define PORT_NUMBER LDAP_PORT
#endif
#ifndef PAM_EXTERN
#ifdef PAM_STATIC
#define PAM_EXTERN static
#else
#define PAM_EXTERN extern
#endif
#endif
#include <sys/types.h>
#include <pwd.h>
#define TOKEN_LEN 44
#define TOKEN_ID_LEN 12
/*
* This function will look for users name with valid user token id. It
* will returns 0 for failure and 1 for success.
*
* File format is as follows:
* <user-name>:<token_id>:<token_id>
* <user-name>:<token_id>
*
*/
static int
check_user_token (const char *authfile,
const char *username, const char *usertoken)
{
static char buf[1024];
char *s_user, *s_token;
int retval = 0;
FILE *opwfile;
opwfile = fopen (authfile, "r");
if (opwfile == NULL)
{
D ((" %s file does not exists.", authfile));
return retval;
}
while (fgets (buf, 1024, opwfile))
{
if (!strncmp (buf, username, strlen (username)))
{
buf[strlen (buf) - 1] = '\0';
D (("Got user record :: %s", buf));
s_user = strtok (buf, ":");
s_token = strtok (NULL, ":");
while (s_token != NULL)
{
if (!strncmp (usertoken, s_token, strlen (usertoken)))
{
D (("Token Found :: %s", s_token));
retval = 1;
break;
}
s_token = strtok (NULL, ":");
}
break;
}
}
fclose (opwfile);
return retval;
}
/*
* Authorize authenticated OTP_ID for login as USERNAME using
* AUTHFILE. Return 0 on failures, otherwise success.
*/
static int
authorize_user_token (const char *authfile,
const char *username,
const char *otp_id)
{
int retval;
if (authfile)
{
/* Administrator had configured the file and specified is name
as an argument for this module.
*/
retval = check_user_token (authfile, username, otp_id);
}
else
{
/* Getting file from user home directory
..... i.e. ~/.yubico/authorized_yubikeys
*/
struct passwd *p;
char *userfile = NULL;
#define USERFILE "/.yubico/authorized_yubikeys"
p = getpwnam (username);
if (p)
{
userfile = malloc ((p->pw_dir ? strlen (p->pw_dir) : 0)
+ strlen (USERFILE) + 1);
if (!userfile)
return 0;
strcpy (userfile, p->pw_dir);
strcat (userfile, USERFILE);
}
retval = check_user_token (userfile, username, otp_id);
free (userfile);
}
return retval;
}
/*
* This function will look in ldap id the token correspond to the
* requested user. It will returns 0 for failure and 1 for success.
*
* For the moment ldaps is not supported. ldap serve can be on a
* remote host.
*
* You need the following parameters in you pam config:
* ldapsever=
* ldapdn=
* user_attr=
* yubi_attr=
*
*/
static int
authorize_user_token_ldap (const char *ldapserver,
const char *ldapdn, const char *user_attr,
const char *yubi_attr, const char *user,
const char *token_id)
{
int retval = 0;
#ifdef HAVE_LIBLDAP
LDAP *ld;
LDAPMessage *result, *e;
BerElement *ber;
char *a;
char **vals;
int i, rc;
/* FIXME: dont' use hard coded buffers here. */
char find[256] = "";
char sr[128] = "(";
char sep[2] = ",";
char eq[2] = "=";
char sren[4] = "=*)";
strcat (find, user_attr);
strcat (find, eq);
strcat (find, user);
strcat (find, sep);
strcat (find, ldapdn);
strcat (sr, yubi_attr);
strcat (sr, sren);
/* Get a handle to an LDAP connection. */
if ((ld = ldap_init (ldapserver, PORT_NUMBER)) == NULL)
{
D (("ldap_init"));
return (0);
}
/* Bind anonymously to the LDAP server. */
rc = ldap_simple_bind_s (ld, NULL, NULL);
if (rc != LDAP_SUCCESS)
{
D (("ldap_simple_bind_s: %s", ldap_err2string (rc)));
return (0);
}
/* Search for the entry. */
D (("ldap-dn: %s", find));
D (("ldap-filter: %s", sr));
if ((rc = ldap_search_ext_s (ld, find, LDAP_SCOPE_BASE,
sr, NULL, 0, NULL, NULL, LDAP_NO_LIMIT,
LDAP_NO_LIMIT, &result)) != LDAP_SUCCESS)
{
D (("ldap_search_ext_s: %s", ldap_err2string (rc)));
return (0);
}
e = ldap_first_entry (ld, result);
if (e != NULL)
{
/* Iterate through each attribute in the entry. */
for (a = ldap_first_attribute (ld, e, &ber);
a != NULL; a = ldap_next_attribute (ld, e, ber))
{
if ((vals = ldap_get_values (ld, e, a)) != NULL)
{
for (i = 0; vals[i] != NULL; i++)
{
if (!strncmp (token_id, vals[i], strlen (token_id)))
{
D (("Token Found :: %s", vals[i]));
retval = 1;
}
}
ldap_value_free (vals);
}
ldap_memfree (a);
}
if (ber != NULL)
{
ber_free (ber, 0);
}
}
ldap_msgfree (result);
ldap_unbind (ld);
#else
D (("Trying to use LDAP, but this function is not compiled in pam_yubico!!"));
D (("Install libldap-dev and then recompile pam_yubico."));
#endif
return retval;
}
struct cfg
{
int client_id;
int debug;
int alwaysok;
int try_first_pass;
int use_first_pass;
char *auth_file;
char *url;
char *ldapserver;
char *ldapdn;
char *user_attr;
char *yubi_attr;
};
static void
parse_cfg (int flags, int argc, const char **argv, struct cfg *cfg)
{
int i;
cfg->client_id = -1;
cfg->debug = 0;
cfg->alwaysok = 0;
cfg->try_first_pass = 0;
cfg->use_first_pass = 0;
cfg->auth_file = NULL;
cfg->url = NULL;
cfg->ldapserver = NULL;
cfg->ldapdn = NULL;
cfg->user_attr = NULL;
cfg->yubi_attr = NULL;
for (i = 0; i < argc; i++)
{
if (strncmp (argv[i], "id=", 3) == 0)
sscanf (argv[i], "id=%d", &cfg->client_id);
if (strcmp (argv[i], "debug") == 0)
cfg->debug = 1;
if (strcmp (argv[i], "alwaysok") == 0)
cfg->alwaysok = 1;
if (strcmp (argv[i], "try_first_pass") == 0)
cfg->try_first_pass = 1;
if (strcmp (argv[i], "use_first_pass") == 0)
cfg->use_first_pass = 1;
if (strncmp (argv[i], "authfile=", 9) == 0)
cfg->auth_file = (char *) argv[i] + 9;
if (strncmp (argv[i], "url=", 4) == 0)
cfg->url = (char *) argv[i] + 4;
if (strncmp (argv[i], "ldapserver=", 11) == 0)
cfg->ldapserver = (char *) argv[i] + 11;
if (strncmp (argv[i], "ldapdn=", 7) == 0)
cfg->ldapdn = (char *) argv[i] + 7;
if (strncmp (argv[i], "user_attr=", 10) == 0)
cfg->user_attr = (char *) argv[i] + 10;
if (strncmp (argv[i], "yubi_attr=", 10) == 0)
cfg->yubi_attr = (char *) argv[i] + 10;
}
if (cfg->debug)
{
D (("called."));
D (("flags %d argc %d", flags, argc));
for (i = 0; i < argc; i++)
D (("argv[%d]=%s", i, argv[i]));
D (("id=%d", cfg->client_id));
D (("debug=%d", cfg->debug));
D (("alwaysok=%d", cfg->alwaysok));
D (("try_first_pass=%d", cfg->try_first_pass));
D (("use_first_pass=%d", cfg->use_first_pass));
D (("authfile=%s", cfg->auth_file ? cfg->auth_file : "(null)"));
D (("ldapserver=%s", cfg->ldapserver ? cfg->ldapserver : "(null)"));
D (("ldapdn=%s", cfg->ldapdn ? cfg->ldapdn : "(null)"));
D (("user_attr=%s", cfg->user_attr ? cfg->user_attr : "(null)"));
D (("yubi_attr=%s", cfg->yubi_attr ? cfg->yubi_attr : "(null)"));
}
}
#define DBG(x) if (cfg.debug) { D(x); }
PAM_EXTERN int
pam_sm_authenticate (pam_handle_t * pamh,
int flags, int argc, const char **argv)
{
int retval, rc;
const char *user = NULL;
const char *password = NULL;
char otp[TOKEN_LEN + 1] = { 0 };
char otp_id[TOKEN_ID_LEN + 1] = { 0 };
int password_len = 0;
int valid_token = 0;
struct pam_conv *conv;
struct pam_message *pmsg[1], msg[1];
struct pam_response *resp;
int nargs = 1;
yubikey_client_t ykc = NULL;
struct cfg cfg;
parse_cfg (flags, argc, argv, &cfg);
retval = pam_get_user (pamh, &user, NULL);
if (retval != PAM_SUCCESS)
{
DBG (("get user returned error: %s", pam_strerror (pamh, retval)));
goto done;
}
DBG (("get user returned: %s", user));
if (cfg.try_first_pass || cfg.use_first_pass)
{
retval = pam_get_item (pamh, PAM_AUTHTOK, (const void **) &password);
if (retval != PAM_SUCCESS)
{
DBG (("get password returned error: %s",
pam_strerror (pamh, retval)));
goto done;
}
DBG (("get password returned: %s", password));
}
if (cfg.use_first_pass && password == NULL)
{
DBG (("use_first_pass set and no password, giving up"));
retval = PAM_AUTH_ERR;
goto done;
}
ykc = yubikey_client_init ();
if (!ykc)
{
DBG (("yubikey_client_init() failed"));
retval = PAM_AUTHINFO_UNAVAIL;
goto done;
}
yubikey_client_set_info (ykc, cfg.client_id, 0, NULL);
if (cfg.url)
yubikey_client_set_url_template (ykc, cfg.url);
if (password == NULL)
{
retval = pam_get_item (pamh, PAM_CONV, (const void **) &conv);
if (retval != PAM_SUCCESS)
{
DBG (("get conv returned error: %s", pam_strerror (pamh, retval)));
goto done;
}
pmsg[0] = &msg[0];
{
const char *query_template = "Yubikey for `%s': ";
size_t len = strlen (query_template) + strlen (user);
size_t wrote;
msg[0].msg = malloc (len);
if (!msg[0].msg)
{
retval = PAM_BUF_ERR;
goto done;
}
wrote = snprintf ((char *) msg[0].msg, len, query_template, user);
if (wrote < 0 || wrote >= len)
{
retval = PAM_BUF_ERR;
goto done;
}
}
msg[0].msg_style = PAM_PROMPT_ECHO_OFF;
resp = NULL;
retval = conv->conv (nargs, (const struct pam_message **) pmsg,
&resp, conv->appdata_ptr);
free ((char *) msg[0].msg);
if (retval != PAM_SUCCESS)
{
DBG (("conv returned error: %s", pam_strerror (pamh, retval)));
goto done;
}
DBG (("conv returned: %s", resp->resp));
password = resp->resp;
}
password_len = strlen (password);
if (password_len < TOKEN_LEN)
{
DBG (("OTP too short: %s", password));
retval = PAM_AUTH_ERR;
goto done;
}
strncpy (otp, password + (password_len - TOKEN_LEN), TOKEN_LEN);
strncpy (otp_id, password + (password_len - TOKEN_LEN), TOKEN_ID_LEN);
DBG (("OTP: %s ID: %s ", otp, otp_id));
/* user entered their system password followed by generated OTP? */
if (password_len > TOKEN_LEN)
{
char *onlypasswd = strdup (password);
onlypasswd[password_len - TOKEN_LEN] = '\0';
DBG (("Password: %s ", onlypasswd));
retval = pam_set_item (pamh, PAM_AUTHTOK, onlypasswd);
free (onlypasswd);
if (retval != PAM_SUCCESS)
{
DBG (("set_item returned error: %s", pam_strerror (pamh, retval)));
goto done;
}
}
else
password = NULL;
rc = yubikey_client_request (ykc, otp);
DBG (("libyubikey-client return value (%d): %s", rc,
yubikey_client_strerror (rc)));
switch (rc)
{
case YUBIKEY_CLIENT_OK:
break;
case YUBIKEY_CLIENT_BAD_OTP:
case YUBIKEY_CLIENT_REPLAYED_OTP:
retval = PAM_AUTH_ERR;
goto done;
default:
retval = PAM_AUTHINFO_UNAVAIL;
goto done;
}
/* authorize the user with supplied token id */
if (cfg.ldapserver != NULL)
valid_token = authorize_user_token_ldap (cfg.ldapserver, cfg.ldapdn,
cfg.user_attr, cfg.yubi_attr,
user, otp_id);
else
valid_token = authorize_user_token (cfg.auth_file, user, otp_id);
if (valid_token == 0)
{
DBG (("Yubikey not authorized to login as user"));
retval = PAM_AUTHINFO_UNAVAIL;
goto done;
}
retval = PAM_SUCCESS;
done:
if (ykc)
yubikey_client_done (&ykc);
if (cfg.alwaysok && retval != PAM_SUCCESS)
{
DBG (("alwaysok needed (otherwise return with %d)", retval));
retval = PAM_SUCCESS;
}
DBG (("done. [%s]", pam_strerror (pamh, retval)));
pam_set_data (pamh, "yubico_setcred_return", (void*) (intptr_t) retval, NULL);
return retval;
}
PAM_EXTERN int
pam_sm_setcred (pam_handle_t * pamh, int flags, int argc, const char **argv)
{
int retval;
int auth_retval;
D (("called."));
/* TODO: ? */
retval = pam_get_data (pamh, "yubico_setcred_return",
&auth_retval);
D (("retval: %d", auth_retval));
if (retval != PAM_SUCCESS)
return PAM_CRED_UNAVAIL;
switch (auth_retval)
{
case PAM_SUCCESS:
retval = PAM_SUCCESS;
break;
case PAM_USER_UNKNOWN:
retval = PAM_USER_UNKNOWN;
break;
case PAM_AUTH_ERR:
default:
retval = PAM_CRED_ERR;
break;
}
D (("done. [%s]", pam_strerror (pamh, retval)));
return retval;
}
PAM_EXTERN int
pam_sm_acct_mgmt (pam_handle_t * pamh, int flags, int argc, const char **argv)
{
int retval;
D (("called."));
/* TODO: ? */
retval = PAM_SUCCESS;
D (("done. [%s]", pam_strerror (pamh, retval)));
return retval;
}
PAM_EXTERN int
pam_sm_open_session (pam_handle_t * pamh,
int flags, int argc, const char **argv)
{
int retval;
D (("called."));
/* TODO: ? */
retval = PAM_SUCCESS;
D (("done. [%s]", pam_strerror (pamh, retval)));
return retval;
}
PAM_EXTERN int
pam_sm_close_session (pam_handle_t * pamh,
int flags, int argc, const char **argv)
{
int retval;
D (("called."));
/* TODO: ? */
retval = PAM_SUCCESS;
D (("done. [%s]", pam_strerror (pamh, retval)));
return retval;
}
PAM_EXTERN int
pam_sm_chauthtok (pam_handle_t * pamh, int flags, int argc, const char **argv)
{
int retval;
D (("called."));
/* TODO: ? */
retval = PAM_SUCCESS;
D (("done. [%s]", pam_strerror (pamh, retval)));
return retval;
}
#ifdef PAM_STATIC
struct pam_module _pam_yubico_modstruct = {
"pam_yubico",
pam_sm_authenticate,
pam_sm_setcred,
pam_sm_acct_mgmt,
pam_sm_open_session,
pam_sm_close_session,
pam_sm_chauthtok
};
#endif
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