/* $NetBSD: pam_krb5.c,v 1.32 2023/09/28 02:31:04 riastradh Exp $ */

/* $NetBSD: pam_krb5.c,v 1.32 2023/09/28 02:31:04 riastradh Exp $ */

/*-
* This pam_krb5 module contains code that is:
* Copyright (c) Derrick J. Brashear, 1996. All rights reserved.
* Copyright (c) Frank Cusack, 1999-2001. All rights reserved.
* Copyright (c) Jacques A. Vidrine, 2000-2001. All rights reserved.
* Copyright (c) Nicolas Williams, 2001. All rights reserved.
* Copyright (c) Perot Systems Corporation, 2001. All rights reserved.
* Copyright (c) Mark R V Murray, 2001. All rights reserved.
* Copyright (c) Networks Associates Technology, Inc., 2002-2005.
* All rights reserved.
*
* Portions of this software were developed for the FreeBSD Project by
* ThinkSec AS and NAI Labs, the Security Research Division of Network
* Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035
* ("CBOSS"), as part of the DARPA CHATS research program.
*
* 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
* notices, and the entire permission notice in its entirety,
* including the disclaimer of warranties.
* 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. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* ALTERNATIVELY, this product may be distributed under the terms of
* the GNU Public License, in which case the provisions of the GPL are
* required INSTEAD OF the above restrictions. (This clause is
* necessary due to a potential bad interaction between the GPL and
* the restrictions contained in a BSD-style copyright.)
*
* THIS SOFTWARE IS PROVIDED ``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 AUTHOR 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 <sys/cdefs.h>
#ifdef __FreeBSD__
__FBSDID("$FreeBSD: src/lib/libpam/modules/pam_krb5/pam_krb5.c,v 1.22 2005/01/24 16:49:50 rwatson Exp $");
#else
__RCSID("$NetBSD: pam_krb5.c,v 1.32 2023/09/28 02:31:04 riastradh Exp $");
#endif

#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <limits.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>

#include <krb5/krb5.h>
#include <krb5/com_err.h>
#include <krb5/parse_time.h>

#define PAM_SM_AUTH
#define PAM_SM_ACCOUNT
#define PAM_SM_PASSWORD

#include <security/pam_appl.h>
#include <security/pam_modules.h>
#include <security/pam_mod_misc.h>
#include <security/openpam.h>

#define COMPAT_HEIMDAL
/* #define COMPAT_MIT */

static void log_krb5(krb5_context, krb5_error_code, struct syslog_data *,
const char *, ...) __printflike(4, 5);
static int verify_krb_v5_tgt_begin(krb5_context, char *, int,
const char **, krb5_principal *, char[static BUFSIZ], struct syslog_data *);
static int verify_krb_v5_tgt(krb5_context, krb5_ccache, char *, int,
const char *, krb5_principal, char[static BUFSIZ], struct syslog_data *);
static void verify_krb_v5_tgt_cleanup(krb5_context, int,
const char *, krb5_principal, char[static BUFSIZ], struct syslog_data *);
static void cleanup_cache(pam_handle_t *, void *, int);
static const char *compat_princ_component(krb5_context, krb5_principal, int);
static void compat_free_data_contents(krb5_context, krb5_data *);

#define USER_PROMPT "Username: "
#define PASSWORD_PROMPT "%s's password:"
#define NEW_PASSWORD_PROMPT "New Password:"

#define PAM_OPT_CCACHE "ccache"
#define PAM_OPT_DEBUG "debug"
#define PAM_OPT_FORWARDABLE "forwardable"
#define PAM_OPT_RENEWABLE "renewable"
#define PAM_OPT_NO_CCACHE "no_ccache"
#define PAM_OPT_REUSE_CCACHE "reuse_ccache"
#define PAM_OPT_ALLOW_KDC_SPOOF "allow_kdc_spoof"

/*
* authentication management
*/
PAM_EXTERN int
pam_sm_authenticate(pam_handle_t *pamh, int flags __unused,
int argc __unused, const char *argv[] __unused)
{
krb5_error_code krbret;
krb5_context pam_context;
int debug;
const char *auth_service;
krb5_principal auth_princ;
char auth_phost[BUFSIZ];
struct syslog_data auth_data = SYSLOG_DATA_INIT;
krb5_creds creds;
krb5_principal princ;
krb5_ccache ccache;
krb5_get_init_creds_opt *opts = NULL;
struct passwd *pwd, pwres;
int retval;
const void *ccache_data;
const char *user, *pass;
const void *sourceuser, *service;
char *principal, *princ_name, *ccache_name, luser[32], *srvdup;
char password_prompt[80];
char pwbuf[1024];
const char *rtime;

princ_name = NULL;
retval = pam_get_user(pamh, &user, USER_PROMPT);
if (retval != PAM_SUCCESS)
return (retval);

PAM_LOG("Got user: %s", user);

retval = pam_get_item(pamh, PAM_RUSER, &sourceuser);
if (retval != PAM_SUCCESS)
return (retval);

PAM_LOG("Got ruser: %s", (const char *)sourceuser);

service = NULL;
pam_get_item(pamh, PAM_SERVICE, &service);
if (service == NULL)
service = "unknown";

PAM_LOG("Got service: %s", (const char *)service);

if ((srvdup = strdup(service)) == NULL) {
retval = PAM_BUF_ERR;
goto cleanup6;
}

krbret = krb5_init_context(&pam_context);
if (krbret != 0) {
PAM_VERBOSE_ERROR("Kerberos 5 error");
retval = PAM_SERVICE_ERR;
goto cleanup5;
}

PAM_LOG("Context initialised");

debug = openpam_get_option(pamh, PAM_OPT_DEBUG) ? 1 : 0;
krbret = verify_krb_v5_tgt_begin(pam_context, srvdup, debug,
&auth_service, &auth_princ, auth_phost, &auth_data);
if (krbret != 0) { /* failed to find key */
/* Keytab or service key does not exist */
if (debug)
log_krb5(pam_context, krbret, &auth_data,
"pam_krb5: verify_krb_v5_tgt: "
"krb5_kt_read_service_key");
/*
* Give up now because we can't authenticate the KDC
* with a keytab, unless the administrator asked to
* have the traditional behaviour of being vulnerable
* to spoofed KDCs.
*/
if (!openpam_get_option(pamh, PAM_OPT_ALLOW_KDC_SPOOF)) {
retval = PAM_SERVICE_ERR;
goto cleanup4;
}
}

krbret = krb5_get_init_creds_opt_alloc(pam_context, &opts);
if (krbret != 0) {
PAM_VERBOSE_ERROR("Kerberos 5 error");
retval = PAM_SERVICE_ERR;
goto cleanup4;
}

if (openpam_get_option(pamh, PAM_OPT_FORWARDABLE))
krb5_get_init_creds_opt_set_forwardable(opts, 1);

if ((rtime = openpam_get_option(pamh, PAM_OPT_RENEWABLE)) != NULL) {
krb5_deltat renew;
char rbuf[80], *rp;

if (*rtime) {
(void)strlcpy(rbuf, rtime, sizeof(rbuf));
rtime = rbuf;
for (rp = rbuf; *rp; rp++)
if (*rp == '_')
*rp = ' ';
}
else
rtime = "1 month";
renew = parse_time(rtime, "s");
krb5_get_init_creds_opt_set_renew_life(opts, renew);
}

PAM_LOG("Credentials initialised");

krbret = krb5_cc_register(pam_context, &krb5_mcc_ops, FALSE);
if (krbret != 0 && krbret != KRB5_CC_TYPE_EXISTS) {
PAM_VERBOSE_ERROR("Kerberos 5 error");
retval = PAM_SERVICE_ERR;
goto cleanup3;
}

PAM_LOG("Done krb5_cc_register()");

/* Get principal name */
if (openpam_get_option(pamh, PAM_OPT_AUTH_AS_SELF))
asprintf(&principal, "%s/%s", (const char *)sourceuser, user);
else
principal = strdup(user);

PAM_LOG("Created principal: %s", principal);

krbret = krb5_parse_name(pam_context, principal, &princ);
free(principal);
if (krbret != 0) {
log_krb5(pam_context, krbret, NULL, "krb5_parse_name");
PAM_VERBOSE_ERROR("Kerberos 5 error");
retval = PAM_SERVICE_ERR;
goto cleanup3;
}

PAM_LOG("Done krb5_parse_name()");

/* Now convert the principal name into something human readable */
krbret = krb5_unparse_name(pam_context, princ, &princ_name);
if (krbret != 0) {
log_krb5(pam_context, krbret, NULL, "krb5_unparse_name");
PAM_VERBOSE_ERROR("Kerberos 5 error");
retval = PAM_SERVICE_ERR;
goto cleanup2;
}

PAM_LOG("Got principal: %s", princ_name);

/* Get password */
(void) snprintf(password_prompt, sizeof(password_prompt),
PASSWORD_PROMPT, princ_name);
retval = pam_get_authtok(pamh, PAM_AUTHTOK, &pass, password_prompt);
if (retval != PAM_SUCCESS)
goto cleanup2;

PAM_LOG("Got password");

/* Verify the local user exists (AFTER getting the password) */
if (strchr(user, '@')) {
/* get a local account name for this principal */
krbret = krb5_aname_to_localname(pam_context, princ,
sizeof(luser), luser);
if (krbret != 0) {
PAM_VERBOSE_ERROR("Kerberos 5 error");
log_krb5(pam_context, krbret, NULL,
"krb5_aname_to_localname");
retval = PAM_USER_UNKNOWN;
goto cleanup2;
}

retval = pam_set_item(pamh, PAM_USER, luser);
if (retval != PAM_SUCCESS)
goto cleanup2;

PAM_LOG("PAM_USER Redone");
}

if (getpwnam_r(user, &pwres, pwbuf, sizeof(pwbuf), &pwd) != 0 ||
pwd == NULL) {
retval = PAM_USER_UNKNOWN;
goto cleanup2;
}

PAM_LOG("Done getpwnam_r()");

/* Get a TGT */
memset(&creds, 0, sizeof(krb5_creds));
krbret = krb5_get_init_creds_password(pam_context, &creds, princ,
pass, NULL, pamh, 0, NULL, opts);
if (krbret != 0) {
PAM_VERBOSE_ERROR("Kerberos 5 error");
log_krb5(pam_context, krbret, NULL,
"krb5_get_init_creds_password");
retval = PAM_AUTH_ERR;
goto cleanup2;
}

PAM_LOG("Got TGT");

/* Generate a temporary cache */
krbret = krb5_cc_new_unique(pam_context, "MEMORY", NULL, &ccache);
if (krbret != 0) {
PAM_VERBOSE_ERROR("Kerberos 5 error");
log_krb5(pam_context, krbret, NULL, "krb5_cc_gen_new");
retval = PAM_SERVICE_ERR;
goto cleanup;
}
krbret = krb5_cc_initialize(pam_context, ccache, princ);
if (krbret != 0) {
PAM_VERBOSE_ERROR("Kerberos 5 error");
log_krb5(pam_context, krbret, NULL, "krb5_cc_initialize");
retval = PAM_SERVICE_ERR;
goto cleanup;
}
krbret = krb5_cc_store_cred(pam_context, ccache, &creds);
if (krbret != 0) {
PAM_VERBOSE_ERROR("Kerberos 5 error");
log_krb5(pam_context, krbret, NULL, "krb5_cc_store_cred");
krb5_cc_destroy(pam_context, ccache);
retval = PAM_SERVICE_ERR;
goto cleanup;
}

PAM_LOG("Credentials stashed");

/* Verify them */
krbret = verify_krb_v5_tgt(pam_context, ccache, srvdup,
debug,
auth_service, auth_princ, auth_phost, &auth_data);
if (krbret == -1) {
PAM_VERBOSE_ERROR("Kerberos 5 error");
krb5_cc_destroy(pam_context, ccache);
retval = PAM_AUTH_ERR;
goto cleanup;
}

PAM_LOG("Credentials stash verified");

retval = pam_get_data(pamh, "ccache", &ccache_data);
if (retval == PAM_SUCCESS) {
krb5_cc_destroy(pam_context, ccache);
PAM_VERBOSE_ERROR("Kerberos 5 error");
retval = PAM_AUTH_ERR;
goto cleanup;
}

PAM_LOG("Credentials stash not pre-existing");

asprintf(&ccache_name, "%s:%s", krb5_cc_get_type(pam_context,
ccache), krb5_cc_get_name(pam_context, ccache));
if (ccache_name == NULL) {
PAM_VERBOSE_ERROR("Kerberos 5 error");
retval = PAM_BUF_ERR;
goto cleanup;
}
retval = pam_set_data(pamh, "ccache", ccache_name, cleanup_cache);
if (retval != 0) {
krb5_cc_destroy(pam_context, ccache);
PAM_VERBOSE_ERROR("Kerberos 5 error");
retval = PAM_SERVICE_ERR;
goto cleanup;
}

PAM_LOG("Credentials stash saved");

cleanup:
krb5_free_cred_contents(pam_context, &creds);
PAM_LOG("Done cleanup");
cleanup2:
krb5_free_principal(pam_context, princ);
PAM_LOG("Done cleanup2");
cleanup3:
if (princ_name)
free(princ_name);

if (opts)
krb5_get_init_creds_opt_free(pam_context, opts);
cleanup4:
verify_krb_v5_tgt_cleanup(pam_context, debug,
auth_service, auth_princ, auth_phost, &auth_data);

krb5_free_context(pam_context);
cleanup5:
free(srvdup);

PAM_LOG("Done cleanup5");
cleanup6:
if (retval != PAM_SUCCESS)
PAM_VERBOSE_ERROR("Kerberos 5 refuses you");

return (retval);
}

PAM_EXTERN int
pam_sm_setcred(pam_handle_t *pamh, int flags,
int argc __unused, const char *argv[] __unused)
{

krb5_error_code krbret;
krb5_context pam_context;
krb5_principal princ;
krb5_creds creds;
krb5_ccache ccache_temp, ccache_perm;
krb5_cc_cursor cursor;
struct passwd *pwd = NULL, pwres;
int retval;
const char *cache_name, *q;
const void *user;
const void *cache_data;
char *cache_name_buf = NULL, *p, *cache_name_buf2 = NULL;
char pwbuf[1024];

uid_t euid;
gid_t egid;

if (flags & PAM_DELETE_CRED)
return (PAM_SUCCESS); /* XXX */

if (!(flags & (PAM_REFRESH_CRED|PAM_REINITIALIZE_CRED|PAM_ESTABLISH_CRED)))
return (PAM_SERVICE_ERR);

/* If a persistent cache isn't desired, stop now. */
if (openpam_get_option(pamh, PAM_OPT_NO_CCACHE))
return (PAM_SUCCESS);

PAM_LOG("Establishing credentials");

/* Get username */
retval = pam_get_item(pamh, PAM_USER, &user);
if (retval != PAM_SUCCESS)
return (retval);

PAM_LOG("Got user: %s", (const char *)user);

krbret = krb5_init_context(&pam_context);
if (krbret != 0) {
PAM_LOG("Error krb5_init_context() failed");
return (PAM_SERVICE_ERR);
}

PAM_LOG("Context initialised");

euid = geteuid(); /* Usually 0 */
egid = getegid();

PAM_LOG("Got euid, egid: %d %d", euid, egid);

/* Retrieve the temporary cache */
retval = pam_get_data(pamh, "ccache", &cache_data);
if (retval != PAM_SUCCESS) {
retval = PAM_CRED_UNAVAIL;
goto cleanup3;
}
krbret = krb5_cc_resolve(pam_context, cache_data, &ccache_temp);
if (krbret != 0) {
log_krb5(pam_context, krbret, NULL, "krb5_cc_resolve(\"%s\")",
(const char *)cache_data);
retval = PAM_SERVICE_ERR;
goto cleanup3;
}

/* Get the uid. This should exist. */
if (getpwnam_r(user, &pwres, pwbuf, sizeof(pwbuf), &pwd) != 0 ||
pwd == NULL) {
retval = PAM_USER_UNKNOWN;
goto cleanup3;
}

PAM_LOG("Done getpwnam_r()");

/* Avoid following a symlink as root */
if (setegid(pwd->pw_gid)) {
retval = PAM_SERVICE_ERR;
goto cleanup3;
}
if (seteuid(pwd->pw_uid)) {
retval = PAM_SERVICE_ERR;
goto cleanup3;
}

PAM_LOG("Done setegid() & seteuid()");

if (flags & (PAM_REFRESH_CRED|PAM_REINITIALIZE_CRED)) {
cache_name = getenv("KRB5CCNAME");
if (!cache_name)
goto cleanup3;
} else {
size_t len = PATH_MAX + 16;
/* Get the cache name */
cache_name = openpam_get_option(pamh, PAM_OPT_CCACHE);
if (cache_name == NULL) {
asprintf(&cache_name_buf, "FILE:/tmp/krb5cc_%d", pwd->pw_uid);
cache_name = cache_name_buf;
}

cache_name_buf2 = p = calloc(len, sizeof(char));
q = cache_name;

if (p == NULL) {
PAM_LOG("Error malloc(): failure");
retval = PAM_BUF_ERR;
goto cleanup3;
}
cache_name = p;

/* convert %u and %p */
while (*q) {
int l;
if (*q == '%') {
q++;
if (*q == 'u') {
l = snprintf(p, len, "%d", pwd->pw_uid);
}
else if (*q == 'p') {
l = snprintf(p, len, "%d", getpid());
}
else {
/* Not a special token */
if (!len)
goto truncated;
*p = '%';
l = 1;
q--;
}
if ((size_t)l > len) {
truncated: PAM_LOG("string truncation failure");
retval = PAM_BUF_ERR;
goto cleanup3;
}
q++;
}
else {
if (!len)
goto truncated;
*p = *q++;
l = 1;
}
p += l;
len -= (size_t)l;
}
if (!len)
goto truncated;
*p = '\0';
}

PAM_LOG("Got cache_name: %s", cache_name);

/* Initialize the new ccache */
krbret = krb5_cc_get_principal(pam_context, ccache_temp, &princ);
if (krbret != 0) {
log_krb5(pam_context, krbret, NULL, "krb5_cc_get_principal");
retval = PAM_SERVICE_ERR;
goto cleanup3;
}
krbret = krb5_cc_resolve(pam_context, cache_name, &ccache_perm);
if (krbret != 0) {
log_krb5(pam_context, krbret, NULL, "krb5_cc_resolve");
retval = PAM_SERVICE_ERR;
goto cleanup2;
}

krbret = krb5_cc_initialize(pam_context, ccache_perm, princ);
if (krbret != 0) {
log_krb5(pam_context, krbret, NULL, "krb5_cc_initialize");
retval = PAM_SERVICE_ERR;
goto cleanup2;
}

PAM_LOG("Cache initialised");

/* Prepare for iteration over creds */
krbret = krb5_cc_start_seq_get(pam_context, ccache_temp, &cursor);
if (krbret != 0) {
log_krb5(pam_context, krbret, NULL, "krb5_cc_start_seq_get");
krb5_cc_destroy(pam_context, ccache_perm);
retval = PAM_SERVICE_ERR;
goto cleanup2;
}

PAM_LOG("Prepared for iteration");

/* Copy the creds (should be two of them) */
while ((krbret = krb5_cc_next_cred(pam_context, ccache_temp,
&cursor, &creds)) == 0) {

krbret = krb5_cc_store_cred(pam_context, ccache_perm, &creds);
if (krbret != 0) {
log_krb5(pam_context, krbret, NULL,
"krb5_cc_store_cred");
krb5_cc_destroy(pam_context, ccache_perm);
krb5_free_cred_contents(pam_context, &creds);
retval = PAM_SERVICE_ERR;
goto cleanup2;
}

krb5_free_cred_contents(pam_context, &creds);
PAM_LOG("Iteration");
}

krb5_cc_end_seq_get(pam_context, ccache_temp, &cursor);

PAM_LOG("Done iterating");

if (flags & PAM_ESTABLISH_CRED) {
if (strstr(cache_name, "FILE:") == cache_name) {
if (chown(&cache_name[5], pwd->pw_uid, pwd->pw_gid) == -1) {
PAM_LOG("Error chown(): %s", strerror(errno));
krb5_cc_destroy(pam_context, ccache_perm);
retval = PAM_SERVICE_ERR;
goto cleanup2;
}
PAM_LOG("Done chown()");

if (chmod(&cache_name[5], (S_IRUSR | S_IWUSR)) == -1) {
PAM_LOG("Error chmod(): %s", strerror(errno));
krb5_cc_destroy(pam_context, ccache_perm);
retval = PAM_SERVICE_ERR;
goto cleanup2;
}
PAM_LOG("Done chmod()");
}
}

krb5_cc_close(pam_context, ccache_perm);

PAM_LOG("Cache closed");

retval = pam_setenv(pamh, "KRB5CCNAME", cache_name, 1);
if (retval != PAM_SUCCESS) {
PAM_LOG("Error pam_setenv(): %s", pam_strerror(pamh, retval));
retval = PAM_SERVICE_ERR;
goto cleanup2;
}

PAM_LOG("Environment done: KRB5CCNAME=%s", cache_name);

cleanup2:
krb5_free_principal(pam_context, princ);
PAM_LOG("Done cleanup2");
cleanup3:
krb5_free_context(pam_context);
PAM_LOG("Done cleanup3");

seteuid(euid);
setegid(egid);

PAM_LOG("Done seteuid() & setegid()");

if (cache_name_buf != NULL)
free(cache_name_buf);
if (cache_name_buf2 != NULL)
free(cache_name_buf2);

return (retval);
}

/*
* account management
*/
PAM_EXTERN int
pam_sm_acct_mgmt(pam_handle_t *pamh, int flags __unused,
int argc __unused, const char *argv[] __unused)
{
krb5_error_code krbret;
krb5_context pam_context;
krb5_ccache ccache;
krb5_principal princ;
int retval;
const void *user;
const void *ccache_name;

retval = pam_get_item(pamh, PAM_USER, &user);
if (retval != PAM_SUCCESS)
return (retval);

PAM_LOG("Got user: %s", (const char *)user);

retval = pam_get_data(pamh, "ccache", &ccache_name);
if (retval != PAM_SUCCESS)
return (PAM_SUCCESS);

PAM_LOG("Got credentials");

krbret = krb5_init_context(&pam_context);
if (krbret != 0) {
PAM_LOG("Error krb5_init_context() failed");
return (PAM_PERM_DENIED);
}

PAM_LOG("Context initialised");

krbret = krb5_cc_resolve(pam_context, (const char *)ccache_name, &ccache);
if (krbret != 0) {
log_krb5(pam_context, krbret, NULL, "krb5_cc_resolve(\"%s\")",
(const char *)ccache_name);
krb5_free_context(pam_context);
return (PAM_PERM_DENIED);
}

PAM_LOG("Got ccache %s", (const char *)ccache_name);

krbret = krb5_cc_get_principal(pam_context, ccache, &princ);
if (krbret != 0) {
log_krb5(pam_context, krbret, NULL, "krb5_cc_get_principal");
retval = PAM_PERM_DENIED;
goto cleanup;
}

PAM_LOG("Got principal");

if (krb5_kuserok(pam_context, princ, (const char *)user))
retval = PAM_SUCCESS;
else
retval = PAM_PERM_DENIED;
krb5_free_principal(pam_context, princ);

PAM_LOG("Done kuserok()");

cleanup:
krb5_free_context(pam_context);
PAM_LOG("Done cleanup");

return (retval);

}

/*
* password management
*/
PAM_EXTERN int
pam_sm_chauthtok(pam_handle_t *pamh, int flags,
int argc __unused, const char *argv[] __unused)
{
krb5_error_code krbret;
krb5_context pam_context;
krb5_creds creds;
krb5_principal princ;
krb5_get_init_creds_opt *opts;
krb5_data result_code_string, result_string;
int result_code, retval;
const char *pass;
const void *user;
char *princ_name, *passdup;
char password_prompt[80];

princ_name = NULL;
if (flags & PAM_PRELIM_CHECK) {
/* Nothing to do here. */
return (PAM_SUCCESS);
}

if (!(flags & PAM_UPDATE_AUTHTOK)) {
PAM_LOG("Illegal flags argument");
return (PAM_ABORT);
}

retval = pam_get_item(pamh, PAM_USER, &user);
if (retval != PAM_SUCCESS)
return (retval);

PAM_LOG("Got user: %s", (const char *)user);

krbret = krb5_init_context(&pam_context);
if (krbret != 0) {
PAM_LOG("Error krb5_init_context() failed");
return (PAM_SERVICE_ERR);
}

PAM_LOG("Context initialised");

krbret = krb5_get_init_creds_opt_alloc(pam_context, &opts);
if (krbret != 0) {
PAM_LOG("Error krb5_init_context() failed");
return (PAM_SERVICE_ERR);
}

krb5_get_init_creds_opt_set_tkt_life(opts, 300);
krb5_get_init_creds_opt_set_forwardable(opts, FALSE);
krb5_get_init_creds_opt_set_proxiable(opts, FALSE);

PAM_LOG("Credentials options initialised");

/* Get principal name */
krbret = krb5_parse_name(pam_context, (const char *)user, &princ);
if (krbret != 0) {
log_krb5(pam_context, krbret, NULL, "krb5_parse_name");
retval = PAM_USER_UNKNOWN;
goto cleanup3;
}

/* Now convert the principal name into something human readable */
krbret = krb5_unparse_name(pam_context, princ, &princ_name);
if (krbret != 0) {
log_krb5(pam_context, krbret, NULL, "krb5_unparse_name");
retval = PAM_SERVICE_ERR;
goto cleanup2;
}

PAM_LOG("Got principal: %s", princ_name);

/* Get password */
(void) snprintf(password_prompt, sizeof(password_prompt),
PASSWORD_PROMPT, princ_name);
retval = pam_get_authtok(pamh, PAM_OLDAUTHTOK, &pass, password_prompt);
if (retval != PAM_SUCCESS)
goto cleanup2;

PAM_LOG("Got password");

memset(&creds, 0, sizeof(krb5_creds));
krbret = krb5_get_init_creds_password(pam_context, &creds, princ,
pass, NULL, pamh, 0, "kadmin/changepw", opts);
if (krbret != 0) {
log_krb5(pam_context, krbret, NULL,
"krb5_get_init_creds_password");
retval = PAM_AUTH_ERR;
goto cleanup2;
}

PAM_LOG("Credentials established");

/* Now get the new password */
for (;;) {
retval = pam_get_authtok(pamh,
PAM_AUTHTOK, &pass, NEW_PASSWORD_PROMPT);
if (retval != PAM_TRY_AGAIN)
break;
pam_error(pamh, "Mismatch; try again, EOF to quit.");
}
if (retval != PAM_SUCCESS)
goto cleanup;

PAM_LOG("Got new password");

/* Change it */
if ((passdup = strdup(pass)) == NULL) {
retval = PAM_BUF_ERR;
goto cleanup;
}

krb5_data_zero(&result_code_string);
krb5_data_zero(&result_string);

krbret = krb5_set_password(pam_context, &creds, passdup, princ,
&result_code, &result_code_string, &result_string);
free(passdup);
if (krbret != 0) {
log_krb5(pam_context, krbret, NULL, "Unable to set password");
retval = PAM_AUTHTOK_ERR;
goto cleanup;
}
if (result_code) {
pam_info(pamh, "%s%s%.*s",
krb5_passwd_result_to_string(pam_context, result_code),
result_string.length > 0 ? ": " : "",
(int)result_string.length,
result_string.length > 0 ? (char *)result_string.data : "");
retval = PAM_AUTHTOK_ERR;
} else {
PAM_LOG("Password changed");
}

krb5_data_free(&result_string);
krb5_data_free(&result_code_string);

cleanup:
krb5_free_cred_contents(pam_context, &creds);
PAM_LOG("Done cleanup");
cleanup2:
krb5_free_principal(pam_context, princ);
PAM_LOG("Done cleanup2");
cleanup3:
if (princ_name)
free(princ_name);

if (opts)
krb5_get_init_creds_opt_free(pam_context, opts);

krb5_free_context(pam_context);

PAM_LOG("Done cleanup3");

return (retval);
}

PAM_MODULE_ENTRY("pam_krb5");

static void
log_krb5(krb5_context ctx, krb5_error_code err,
struct syslog_data *data, const char *fmt, ...)
{
char b1[1024], b2[1024];
const char *errtxt;
va_list ap;

va_start(ap, fmt);
vsnprintf(b1, sizeof(b1), fmt, ap);
va_end(ap);
if (ctx)
errtxt = krb5_get_error_message(ctx, err);
else
errtxt = NULL;
if (errtxt != NULL) {
snprintf(b2, sizeof(b2), "%s", errtxt);
krb5_free_error_message(ctx, errtxt);
} else {
snprintf(b2, sizeof(b2), "unknown %d", (int)err);
}
if (data)
syslog_r(LOG_DEBUG, data, "%s (%s)", b1, b2);
else
PAM_LOG("%s (%s)", b1, b2);
}

/*
* This routine with some modification is from the MIT V5B6 appl/bsd/login.c
* Modified by Sam Hartman <[email protected]> to support PAM services
* for Debian.
*
* Verify the Kerberos ticket-granting ticket just retrieved for the
* user. If the Kerberos server doesn't respond, assume the user is
* trying to fake us out (since we DID just get a TGT from what is
* supposedly our KDC). If the host/<host> service is unknown (i.e.,
* the local keytab doesn't have it), and we cannot find another
* service we do have, let her in.
*
* - verify_krb_v5_tgt_begin returns a krb5 error code.
* - verify_krb_v5_tgt returns 0 on success, -1 on failure.
*/
/* ARGSUSED */
static int
verify_krb_v5_tgt_begin(krb5_context context, char *pam_service, int debug,
const char **servicep, krb5_principal *princp, char phost[static BUFSIZ],
struct syslog_data *datap)
{
krb5_error_code retval;
krb5_principal princ;
krb5_keyblock *keyblock;
const char *services[3], **service;

*servicep = NULL;
*princp = NULL;

if (debug)
openlog_r("pam_krb5", LOG_PID, LOG_AUTHPRIV, datap);

/* If possible we want to try and verify the ticket we have
* received against a keytab. We will try multiple service
* principals, including at least the host principal and the PAM
* service principal. The host principal is preferred because access
* to that key is generally sufficient to compromise root, while the
* service key for this PAM service may be less carefully guarded.
* It is important to check the keytab first before the KDC so we do
* not get spoofed by a fake KDC.
*/
services[0] = "host";
services[1] = pam_service;
services[2] = NULL;
keyblock = 0;
retval = -1;
for (service = &services[0]; *service != NULL; service++) {
retval = krb5_sname_to_principal(context, NULL, *service,
KRB5_NT_SRV_HST, &princ);
if (retval != 0 && debug)
log_krb5(context, retval, datap,
"pam_krb5: verify_krb_v5_tgt: "
"krb5_sname_to_principal");
if (retval != 0)
return (retval);

/* Extract the name directly. */
strlcpy(phost, compat_princ_component(context, princ, 1),
BUFSIZ);

/*
* Do we have service/<host> keys?
* (use default/configured keytab, kvno IGNORE_VNO to get the
* first match, and ignore enctype.)
*/
retval = krb5_kt_read_service_key(context, NULL, princ, 0, 0,
&keyblock);
if (retval != 0)
continue;
*servicep = *service;
*princp = princ;
break;
}
if (keyblock)
krb5_free_keyblock(context, keyblock);

return (retval);
}

static int
verify_krb_v5_tgt(krb5_context context, krb5_ccache ccache,
char *pam_service, int debug,
const char *service, krb5_principal princ, char phost[static BUFSIZ],
struct syslog_data *datap)
{
krb5_error_code retval;
krb5_auth_context auth_context = NULL;
krb5_data packet;

if (service == NULL)
return (0); /* uncertain, can't authenticate KDC */

packet.data = 0;

/* Talk to the kdc and construct the ticket. */
auth_context = NULL;
retval = krb5_mk_req(context, &auth_context, 0, service, phost,
NULL, ccache, &packet);
if (auth_context) {
krb5_auth_con_free(context, auth_context);
auth_context = NULL; /* setup for rd_req */
}
if (retval) {
if (debug)
log_krb5(context, retval, datap,
"pam_krb5: verify_krb_v5_tgt: "
"krb5_mk_req");
retval = -1;
goto cleanup;
}

/* Try to use the ticket. */
retval = krb5_rd_req(context, &auth_context, &packet, princ, NULL,
NULL, NULL);
if (retval) {
if (debug)
log_krb5(context, retval, datap,
"pam_krb5: verify_krb_v5_tgt: "
"krb5_rd_req");
retval = -1;
}
else
retval = 1;

cleanup:
if (packet.data)
compat_free_data_contents(context, &packet);
if (auth_context) {
krb5_auth_con_free(context, auth_context);
auth_context = NULL; /* setup for rd_req */
}
return (retval);
}

static void
verify_krb_v5_tgt_cleanup(krb5_context context, int debug,
const char *service, krb5_principal princ, char phost[static BUFSIZ],
struct syslog_data *datap)
{

if (service)
krb5_free_principal(context, princ);
if (debug)
closelog_r(datap);
}

/* Free the memory for cache_name. Called by pam_end() */
/* ARGSUSED */
static void
cleanup_cache(pam_handle_t *pamh __unused, void *data, int pam_end_status __unused)
{
krb5_context pam_context;
krb5_ccache ccache;
krb5_error_code krbret;

if (krb5_init_context(&pam_context))
return;

krbret = krb5_cc_resolve(pam_context, data, &ccache);
if (krbret == 0)
krb5_cc_destroy(pam_context, ccache);
krb5_free_context(pam_context);
free(data);
}

#ifdef COMPAT_HEIMDAL
#ifdef COMPAT_MIT
#error This cannot be MIT and Heimdal compatible!
#endif
#endif

#ifndef COMPAT_HEIMDAL
#ifndef COMPAT_MIT
#error One of COMPAT_MIT and COMPAT_HEIMDAL must be specified!
#endif
#endif

#ifdef COMPAT_HEIMDAL
/* ARGSUSED */
static const char *
compat_princ_component(krb5_context context __unused, krb5_principal princ, int n)
{
return princ->name.name_string.val[n];
}

/* ARGSUSED */
static void
compat_free_data_contents(krb5_context context __unused, krb5_data * data)
{
krb5_xfree(data->data);
}
#endif

#ifdef COMPAT_MIT
static const char *
compat_princ_component(krb5_context context, krb5_principal princ, int n)
{
return krb5_princ_component(context, princ, n)->data;
}

static void
compat_free_data_contents(krb5_context context, krb5_data * data)
{
krb5_free_data_contents(context, data);
}
#endif