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pam_yubico.c
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pam_yubico.c
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/* Written by Simon Josefsson <simon@yubico.com>.
* Copyright (c) 2006-2013 Yubico AB
* Copyright (c) 2011 Tollef Fog Heen <tfheen@err.no>
* 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>
#include <syslog.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <pwd.h>
#include "util.h"
#include "drop_privs.h"
#if HAVE_CR
/* for yubikey_hex_decode and yubikey_hex_p */
#include <yubikey.h>
#include <ykpbkdf2.h>
#endif /* HAVE_CR */
/* 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
#ifdef HAVE_SECURITY_PAM_APPL_H
#include <security/pam_appl.h>
#endif
#ifdef HAVE_SECURITY_PAM_MODULES_H
#include <security/pam_modules.h>
#endif
#ifdef HAVE_LIBLDAP
/* Some functions like ldap_init, ldap_simple_bind_s, ldap_unbind are
deprecated but still available. We will drop support for 'ldapserver'
(in favour of 'ldap_uri' and update to using the new functions instead
soon.
*/
#define LDAP_DEPRECATED 1
#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
#define TOKEN_OTP_LEN 32
#define MAX_TOKEN_ID_LEN 16
#define DEFAULT_TOKEN_ID_LEN 12
enum key_mode {
CHRESP,
CLIENT
};
struct cfg
{
int client_id;
char *client_key;
int debug;
int alwaysok;
int verbose_otp;
int try_first_pass;
int use_first_pass;
char *auth_file;
char *capath;
char *url;
char *ldapserver;
char *ldap_uri;
char *ldapdn;
char *user_attr;
char *yubi_attr;
char *yubi_attr_prefix;
int token_id_length;
enum key_mode mode;
char *chalresp_path;
};
#ifdef DBG
#undef DBG
#endif
#define DBG(x) if (cfg->debug) { D(x); }
/*
* This function will look for users name with valid user token id. It
* will returns -2 if the user is unknown, -1 if the token do not match the user line, 0 for internal 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 (struct cfg *cfg,
const char *authfile,
const char *username,
const char *otp_id)
{
char buf[1024];
char *s_user, *s_token;
int retval = 0;
int fd;
struct stat st;
FILE *opwfile;
fd = open(authfile, O_RDONLY, 0);
if (fd < 0) {
DBG (("Cannot open file: %s (%s)", authfile, strerror(errno)));
return retval;
}
if (fstat(fd, &st) < 0) {
DBG (("Cannot stat file: %s (%s)", authfile, strerror(errno)));
close(fd);
return retval;
}
if (!S_ISREG(st.st_mode)) {
DBG (("%s is not a regular file", authfile));
close(fd);
return retval;
}
opwfile = fdopen(fd, "r");
if (opwfile == NULL) {
DBG (("fdopen: %s", strerror(errno)));
close(fd);
return retval;
}
retval = -2;
while (fgets (buf, 1024, opwfile))
{
if (buf[strlen (buf) - 1] == '\n')
buf[strlen (buf) - 1] = '\0';
DBG (("Authorization line: %s", buf));
s_user = strtok (buf, ":");
if (s_user && strcmp (username, s_user) == 0)
{
DBG (("Matched user: %s", s_user));
retval = -1; //We found at least one line for the user
do
{
s_token = strtok (NULL, ":");
DBG (("Authorization token: %s", s_token));
if (s_token && strcmp (otp_id, s_token) == 0)
{
DBG (("Match user/token as %s/%s", username, otp_id));
fclose (opwfile);
return 1;
}
}
while (s_token != NULL);
}
}
fclose (opwfile);
return retval;
}
/*
* Authorize authenticated OTP_ID for login as USERNAME using
* AUTHFILE. Return -2 if the user is unknown, -1 if the OTP_ID does not match, 0 on internal failures, otherwise success.
*/
static int
authorize_user_token (struct cfg *cfg,
const char *username,
const char *otp_id,
pam_handle_t *pamh)
{
int retval;
if (cfg->auth_file)
{
/* Administrator had configured the file and specified is name
as an argument for this module.
*/
DBG (("Using system-wide auth_file %s", cfg->auth_file));
retval = check_user_token (cfg, cfg->auth_file, username, otp_id);
}
else
{
char *userfile = NULL;
struct passwd *p;
PAM_MODUTIL_DEF_PRIVS(privs);
p = getpwnam (username);
if (p == NULL) {
DBG (("getpwnam: %s", strerror(errno)));
return 0;
}
/* Getting file from user home directory
..... i.e. ~/.yubico/authorized_yubikeys
*/
if (! get_user_cfgfile_path (NULL, "authorized_yubikeys", username, &userfile)) {
D (("Failed figuring out per-user cfgfile"));
return 0;
}
DBG (("Dropping privileges"));
if(pam_modutil_drop_priv(pamh, &privs, p)) {
DBG (("could not drop privileges"));
retval = 0;
goto free_out;
}
retval = check_user_token (cfg, userfile, username, otp_id);
if(pam_modutil_regain_priv(pamh, &privs)) {
DBG (("could not restore privileges"));
retval = 0;
goto free_out;
}
free_out:
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:
* ldapserver= OR ldap_uri=
* ldapdn=
* user_attr=
* yubi_attr=
*
*/
static int
authorize_user_token_ldap (struct cfg *cfg,
const char *user,
const char *token_id)
{
int retval = 0;
int protocol;
#ifdef HAVE_LIBLDAP
int yubi_attr_prefix_len = 0;
LDAP *ld = NULL;
LDAPMessage *result = NULL, *e;
BerElement *ber;
char *a;
char *attrs[2] = {NULL, NULL};
struct berval **vals;
int i, rc;
char *find = NULL;
#endif
DBG(("called"));
#ifdef HAVE_LIBLDAP
if (cfg->user_attr == NULL) {
DBG (("Trying to look up user to YubiKey mapping in LDAP, but user_attr not set!"));
return 0;
}
if (cfg->yubi_attr == NULL) {
DBG (("Trying to look up user to YubiKey mapping in LDAP, but yubi_attr not set!"));
return 0;
}
if (cfg->ldapdn == NULL) {
DBG (("Trying to look up user to YubiKey mapping in LDAP, but ldapdn not set!"));
return 0;
}
/* Get a handle to an LDAP connection. */
if (cfg->ldap_uri)
{
rc = ldap_initialize (&ld, cfg->ldap_uri);
if (rc != LDAP_SUCCESS)
{
DBG (("ldap_init: %s", ldap_err2string (rc)));
retval = 0;
goto done;
}
}
else
{
if ((ld = ldap_init (cfg->ldapserver, PORT_NUMBER)) == NULL)
{
DBG (("ldap_init"));
retval = 0;
goto done;
}
}
/* LDAPv2 is historical -- RFC3494. */
protocol = LDAP_VERSION3;
ldap_set_option (ld, LDAP_OPT_PROTOCOL_VERSION, &protocol);
/* Bind anonymously to the LDAP server. */
rc = ldap_simple_bind_s (ld, NULL, NULL);
if (rc != LDAP_SUCCESS)
{
DBG (("ldap_simple_bind_s: %s", ldap_err2string (rc)));
retval = 0;
goto done;
}
/* Allocation of memory for search strings depending on input size */
i = (strlen(cfg->user_attr) + strlen(cfg->ldapdn) + strlen(user) + 3) * sizeof(char);
if ((find = malloc(i)) == NULL) {
DBG (("Failed allocating %i bytes", i));
retval = 0;
goto done;
}
sprintf (find, "%s=%s,%s", cfg->user_attr, user, cfg->ldapdn);
attrs[0] = (char *) cfg->yubi_attr;
DBG(("LDAP : look up object '%s', ask for attribute '%s'", find, cfg->yubi_attr));
/* Search for the entry. */
if ((rc = ldap_search_ext_s (ld, find, LDAP_SCOPE_BASE,
NULL, attrs, 0, NULL, NULL, LDAP_NO_LIMIT,
LDAP_NO_LIMIT, &result)) != LDAP_SUCCESS)
{
DBG (("ldap_search_ext_s: %s", ldap_err2string (rc)));
retval = 0;
goto done;
}
e = ldap_first_entry (ld, result);
if (e == NULL)
{
DBG (("No result from LDAP search"));
retval = -2;
}
else
{
retval = -1;
/* Iterate through each returned attribute. */
for (a = ldap_first_attribute (ld, e, &ber);
a != NULL; a = ldap_next_attribute (ld, e, ber))
{
if ((vals = ldap_get_values_len (ld, e, a)) != NULL)
{
DBG(("LDAP : Found %i values - checking if any of them match '%s%s'",
ldap_count_values_len(vals),
cfg->yubi_attr_prefix ? cfg->yubi_attr_prefix : "",
token_id));
yubi_attr_prefix_len = cfg->yubi_attr_prefix ? strlen(cfg->yubi_attr_prefix) : 0;
/* Compare each value for the attribute against the token id. */
for (i = 0; vals[i] != NULL; i++)
{
/* Only values containing this prefix are considered. */
if ((!cfg->yubi_attr_prefix || !strncmp (cfg->yubi_attr_prefix, vals[i]->bv_val, yubi_attr_prefix_len)))
{
if(!strncmp (token_id, vals[i]->bv_val + yubi_attr_prefix_len, strlen (token_id)))
{
DBG (("Token Found :: %s", vals[i]->bv_val));
retval = 1;
}
}
}
ldap_value_free_len (vals);
}
ldap_memfree (a);
}
if (ber != NULL)
ber_free (ber, 0);
}
done:
if (result != NULL)
ldap_msgfree (result);
if (ld != NULL)
ldap_unbind (ld);
/* free memory allocated for search strings */
if (find != NULL)
free(find);
#else
DBG (("Trying to use LDAP, but this function is not compiled in pam_yubico!!"));
DBG (("Install libldap-dev and then recompile pam_yubico."));
#endif
return retval;
}
#if HAVE_CR
static int
display_error(pam_handle_t *pamh, const char *message) {
struct pam_conv *conv;
const struct pam_message *pmsg[1];
struct pam_message msg[1];
struct pam_response *resp = NULL;
int retval;
retval = pam_get_item (pamh, PAM_CONV, (const void **) &conv);
if (retval != PAM_SUCCESS) {
D(("get conv returned error: %s", pam_strerror (pamh, retval)));
return retval;
}
pmsg[0] = &msg[0];
msg[0].msg = message;
msg[0].msg_style = PAM_ERROR_MSG;
retval = conv->conv(1, pmsg, &resp, conv->appdata_ptr);
if (retval != PAM_SUCCESS) {
D(("conv returned error: %s", pam_strerror (pamh, retval)));
return retval;
}
D(("conv returned: '%s'", resp->resp));
return retval;
}
#endif /* HAVE_CR */
#if HAVE_CR
static int
do_challenge_response(pam_handle_t *pamh, struct cfg *cfg, const char *username)
{
char *userfile = NULL, *tmpfile = NULL;
FILE *f = NULL;
char buf[CR_RESPONSE_SIZE + 16], response_hex[CR_RESPONSE_SIZE * 2 + 1];
int ret, fd;
unsigned int response_len = 0;
YK_KEY *yk = NULL;
CR_STATE state;
const char *errstr = NULL;
struct passwd *p;
struct stat st;
/* we must declare two sepparate privs structures as they can't be reused */
PAM_MODUTIL_DEF_PRIVS(privs);
PAM_MODUTIL_DEF_PRIVS(privs2);
ret = PAM_AUTH_ERR;
if (! init_yubikey(&yk)) {
DBG(("Failed initializing YubiKey"));
goto out;
}
if (! check_firmware_version(yk, false, true)) {
DBG(("YubiKey does not support Challenge-Response (version 2.2 required)"));
goto out;
}
if (! get_user_challenge_file (yk, cfg->chalresp_path, username, &userfile)) {
DBG(("Failed getting user challenge file for user %s", username));
goto out;
}
DBG(("Loading challenge from file %s", userfile));
p = getpwnam (username);
if (p == NULL) {
DBG (("getpwnam: %s", strerror(errno)));
goto out;
}
/* Drop privileges before opening user file. */
if (pam_modutil_drop_priv(pamh, &privs, p)) {
DBG (("could not drop privileges"));
goto out;
}
fd = open(userfile, O_RDONLY, 0);
if (fd < 0) {
DBG (("Cannot open file: %s (%s)", userfile, strerror(errno)));
goto restpriv_out;
}
if (fstat(fd, &st) < 0) {
DBG (("Cannot stat file: %s (%s)", userfile, strerror(errno)));
close(fd);
goto restpriv_out;
}
if (!S_ISREG(st.st_mode)) {
DBG (("%s is not a regular file", userfile));
close(fd);
goto restpriv_out;
}
f = fdopen(fd, "r");
if (f == NULL) {
DBG (("fdopen: %s", strerror(errno)));
close(fd);
goto restpriv_out;
}
if (! load_chalresp_state(f, &state, cfg->debug))
goto restpriv_out;
if (fclose(f) < 0) {
f = NULL;
goto restpriv_out;
}
f = NULL;
if (pam_modutil_regain_priv(pamh, &privs)) {
DBG (("could not restore privileges"));
goto out;
}
if (! challenge_response(yk, state.slot, state.challenge, state.challenge_len,
true, true, false,
buf, sizeof(buf), &response_len)) {
DBG(("Challenge-response FAILED"));
goto out;
}
/*
* Check YubiKey response against the expected response
*/
yubikey_hex_encode(response_hex, buf, response_len);
if(state.salt_len > 0) { // the expected response has gone through pbkdf2
YK_PRF_METHOD prf_method = {20, yk_hmac_sha1};
yk_pbkdf2(response_hex, (unsigned char*)state.salt, state.salt_len, state.iterations,
(unsigned char*)buf, response_len, &prf_method);
}
if (memcmp(buf, state.response, state.response_len) == 0) {
ret = PAM_SUCCESS;
} else {
DBG(("Unexpected C/R response : %s", response_hex));
goto out;
}
DBG(("Got the expected response, generating new challenge (%i bytes).", CR_CHALLENGE_SIZE));
errstr = "Error generating new challenge, please check syslog or contact your system administrator";
if (generate_random(state.challenge, sizeof(state.challenge))) {
DBG(("Failed generating new challenge!"));
goto out;
}
errstr = "Error communicating with Yubikey, please check syslog or contact your system administrator";
if (! challenge_response(yk, state.slot, state.challenge, CR_CHALLENGE_SIZE,
true, true, false,
buf, sizeof(buf), &response_len)) {
DBG(("Second challenge-response FAILED"));
goto out;
}
/* There is a bug that makes the YubiKey 2.2 send the same response for all challenges
unless HMAC_LT64 is set, check for that here */
if (memcmp(buf, state.response, state.response_len) == 0) {
errstr = "Same response for second challenge, YubiKey should be reconfigured with the option HMAC_LT64";
goto out;
}
/* the yk_* functions leave 'junk' in errno */
errno = 0;
/*
* Write the challenge and response we will expect the next time to the state file.
*/
if (response_len > sizeof(state.response)) {
DBG(("Got too long response ??? (%u/%lu)", response_len, (unsigned long) sizeof(state.response)));
goto out;
}
memcpy (state.response, buf, response_len);
state.response_len = response_len;
/* point to the fresh privs structure.. */
privs = privs2;
/* Drop privileges before creating new challenge file. */
if (pam_modutil_drop_priv(pamh, &privs, p)) {
DBG (("could not drop privileges"));
goto out;
}
/* Write out the new file */
tmpfile = malloc(strlen(userfile) + 1 + 4);
if (! tmpfile)
goto restpriv_out;
strcpy(tmpfile, userfile);
strcat(tmpfile, ".tmp");
fd = open(tmpfile, O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR);
if (fd < 0) {
DBG (("Cannot open file: %s (%s)", tmpfile, strerror(errno)));
goto restpriv_out;
}
f = fdopen(fd, "w");
if (! f) {
close(fd);
goto restpriv_out;
}
errstr = "Error updating Yubikey challenge, please check syslog or contact your system administrator";
if (! write_chalresp_state (f, &state))
goto out;
if (fclose(f) < 0) {
f = NULL;
goto restpriv_out;
}
f = NULL;
if (rename(tmpfile, userfile) < 0) {
goto restpriv_out;
}
if (pam_modutil_regain_priv(pamh, &privs)) {
DBG (("could not restore privileges"));
goto out;
}
DBG(("Challenge-response success!"));
errstr = NULL;
errno = 0;
goto out;
restpriv_out:
if (pam_modutil_regain_priv(pamh, &privs)) {
DBG (("could not restore privileges"));
}
out:
if (yk_errno) {
if (yk_errno == YK_EUSBERR) {
syslog(LOG_ERR, "USB error: %s", yk_usb_strerror());
DBG(("USB error: %s", yk_usb_strerror()));
} else {
syslog(LOG_ERR, "Yubikey core error: %s", yk_strerror(yk_errno));
DBG(("Yubikey core error: %s", yk_strerror(yk_errno)));
}
}
if (errstr)
display_error(pamh, errstr);
if (errno) {
syslog(LOG_ERR, "Challenge response failed: %s", strerror(errno));
DBG(("Challenge response failed: %s", strerror(errno)));
}
if (yk)
yk_close_key(yk);
yk_release();
if (f)
fclose(f);
free(userfile);
free(tmpfile);
return ret;
}
#endif /* HAVE_CR */
static void
parse_cfg (int flags, int argc, const char **argv, struct cfg *cfg)
{
int i;
memset (cfg, 0, sizeof(struct cfg));
cfg->client_id = -1;
cfg->token_id_length = DEFAULT_TOKEN_ID_LEN;
cfg->mode = CLIENT;
for (i = 0; i < argc; i++)
{
if (strncmp (argv[i], "id=", 3) == 0)
sscanf (argv[i], "id=%d", &cfg->client_id);
if (strncmp (argv[i], "key=", 4) == 0)
cfg->client_key = (char *) argv[i] + 4;
if (strcmp (argv[i], "debug") == 0)
cfg->debug = 1;
if (strcmp (argv[i], "alwaysok") == 0)
cfg->alwaysok = 1;
if (strcmp (argv[i], "verbose_otp") == 0)
cfg->verbose_otp = 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], "capath=", 7) == 0)
cfg->capath = (char *) argv[i] + 7;
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], "ldap_uri=", 9) == 0)
cfg->ldap_uri = (char *) argv[i] + 9;
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 (strncmp (argv[i], "yubi_attr_prefix=", 17) == 0)
cfg->yubi_attr_prefix = (char *) argv[i] + 17;
if (strncmp (argv[i], "token_id_length=", 16) == 0)
sscanf (argv[i], "token_id_length=%d", &cfg->token_id_length);
if (strcmp (argv[i], "mode=challenge-response") == 0)
cfg->mode = CHRESP;
if (strcmp (argv[i], "mode=client") == 0)
cfg->mode = CLIENT;
if (strncmp (argv[i], "chalresp_path=", 14) == 0)
cfg->chalresp_path = (char *) argv[i] + 14;
}
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 (("key=%s", cfg->client_key ? cfg->client_key : "(null)"));
D (("debug=%d", cfg->debug));
D (("alwaysok=%d", cfg->alwaysok));
D (("verbose_otp=%d", cfg->verbose_otp));
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 (("ldap_uri=%s", cfg->ldap_uri ? cfg->ldap_uri : "(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)"));
D (("yubi_attr_prefix=%s", cfg->yubi_attr_prefix ? cfg->yubi_attr_prefix : "(null)"));
D (("url=%s", cfg->url ? cfg->url : "(null)"));
D (("capath=%s", cfg->capath ? cfg->capath : "(null)"));
D (("token_id_length=%d", cfg->token_id_length));
D (("mode=%s", cfg->mode == CLIENT ? "client" : "chresp" ));
D (("chalresp_path=%s", cfg->chalresp_path ? cfg->chalresp_path : "(null)"));
}
}
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[MAX_TOKEN_ID_LEN + TOKEN_OTP_LEN + 1] = { 0 };
char otp_id[MAX_TOKEN_ID_LEN + 1] = { 0 };
int password_len = 0;
int skip_bytes = 0;
int valid_token = 0;
struct pam_conv *conv;
const struct pam_message *pmsg[1];
struct pam_message msg[1];
struct pam_response *resp;
int nargs = 1;
ykclient_t *ykc = NULL;
struct cfg cfg_st;
struct cfg *cfg = &cfg_st; /* for DBG macro */
parse_cfg (flags, argc, argv, cfg);
if (cfg->token_id_length > MAX_TOKEN_ID_LEN)
{
DBG (("configuration error: token_id_length too long. Maximum acceptable value : %d", MAX_TOKEN_ID_LEN));
retval = PAM_AUTHINFO_UNAVAIL;
goto done;
}
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->mode == CHRESP) {
#if HAVE_CR
return do_challenge_response(pamh, cfg, user);
#else
DBG (("no support for challenge/response"));
retval = PAM_AUTH_ERR;
goto done;
#endif
}
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;
}
rc = ykclient_init (&ykc);
if (rc != YKCLIENT_OK)
{
DBG (("ykclient_init() failed (%d): %s", rc, ykclient_strerror (rc)));
retval = PAM_AUTHINFO_UNAVAIL;
goto done;
}
rc = ykclient_set_client_b64 (ykc, cfg->client_id, cfg->client_key);
if (rc != YKCLIENT_OK)
{
DBG (("ykclient_set_client_b64() failed (%d): %s",
rc, ykclient_strerror (rc)));
retval = PAM_AUTHINFO_UNAVAIL;
goto done;
}
if (cfg->client_key)
ykclient_set_verify_signature (ykc, 1);
if (cfg->capath)
ykclient_set_ca_path (ykc, cfg->capath);
if (cfg->url)
ykclient_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];
{
#define QUERY_TEMPLATE "YubiKey for `%s': "
size_t len = strlen (QUERY_TEMPLATE) + strlen (user);
int 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 = cfg->verbose_otp ? PAM_PROMPT_ECHO_ON : PAM_PROMPT_ECHO_OFF;
resp = NULL;
retval = conv->conv (nargs, 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;
}
if (resp->resp == NULL)
{
DBG (("conv returned NULL passwd?"));
retval = PAM_AUTH_ERR;
goto done;
}
DBG (("conv returned %lu bytes", (unsigned long) strlen(resp->resp)));
password = resp->resp;
}
password_len = strlen (password);
if (password_len < (cfg->token_id_length + TOKEN_OTP_LEN))
{
DBG (("OTP too short to be considered : %i < %i", password_len, (cfg->token_id_length + TOKEN_OTP_LEN)));
retval = PAM_AUTH_ERR;
goto done;
}
/* In case the input was systempassword+YubiKeyOTP, we want to skip over
"systempassword" when copying the token_id and OTP to separate buffers */
skip_bytes = password_len - (cfg->token_id_length + TOKEN_OTP_LEN);
DBG (("Skipping first %i bytes. Length is %i, token_id set to %i and token OTP always %i.",
skip_bytes, password_len, cfg->token_id_length, TOKEN_OTP_LEN));
/* Copy full YubiKey output (public ID + OTP) into otp */
strncpy (otp, password + skip_bytes, sizeof (otp) - 1);
/* Copy only public ID into otp_id. Destination buffer is zeroed. */
strncpy (otp_id, password + skip_bytes, cfg->token_id_length);
DBG (("OTP: %s ID: %s ", otp, otp_id));
/* user entered their system password followed by generated OTP? */
if (password_len > TOKEN_OTP_LEN + cfg->token_id_length)
{
char *onlypasswd = strdup (password);
if (! onlypasswd) {
retval = PAM_BUF_ERR;
goto done;
}
onlypasswd[password_len - (TOKEN_OTP_LEN + cfg->token_id_length)] = '\0';
DBG (("Extracted a probable system password entered before the OTP - "
"setting item PAM_AUTHTOK"));
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 = ykclient_request (ykc, otp);
DBG (("ykclient return value (%d): %s", rc,
ykclient_strerror (rc)));
switch (rc)
{
case YKCLIENT_OK:
break;
case YKCLIENT_BAD_OTP:
case YKCLIENT_REPLAYED_OTP:
retval = PAM_AUTH_ERR;
goto done;
default:
retval = PAM_AUTHINFO_UNAVAIL;
goto done;
}