+/*
+ * pam_krb5auto - Gets initial credentials non-interactively
+ * Copyright (C) 2004 Fredrik Tolf (fredrik@dolda2000.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+*/
#include <stdlib.h>
+#include <stdio.h>
#include <unistd.h>
+#include <string.h>
+#include <stdarg.h>
+#include <malloc.h>
+#include <syslog.h>
#include <krb5.h>
+#include <pwd.h>
+#include <errno.h>
#define PAM_SM_AUTH
#include <security/pam_modules.h>
+#define DEF_INSTANCE "autologin"
+
+struct options
+{
+ char *realm;
+ char *instance;
+ char *keytab;
+ int debug;
+ int forwardable;
+ int renewable;
+};
+
+struct data
+{
+ krb5_context ctx;
+ krb5_ccache cc;
+ krb5_principal me;
+ krb5_creds initcreds;
+ int hascreds;
+ uid_t uid;
+ gid_t gid;
+};
+
+static void log(int prio, char *format, ...)
+{
+ va_list args;
+ char buf[1024];
+
+ va_start(args, format);
+ snprintf(buf, sizeof(buf), "pam_krb5auto[%i]: %s", getpid(), format);
+ vsyslog(prio, buf, args);
+ va_end(args);
+}
+
+static struct options *parseopts(int argc, const char **argv)
+{
+ int i;
+ struct options *opts;
+ const char *p;
+ int unit;
+
+ opts = malloc(sizeof(*opts));
+ memset(opts, 0, sizeof(*opts));
+ for(i = 0; i < argc; i++) {
+ if(!strncmp(argv[i], "realm=", 6))
+ opts->realm = strdup(argv[i] + 6);
+ if(!strncmp(argv[i], "instance=", 9))
+ opts->instance = strdup(argv[i] + 9);
+ if(!strncmp(argv[i], "keytab=", 7))
+ opts->keytab = strdup(argv[i] + 7);
+ if(!strncmp(argv[i], "renew=", 6)) {
+ p = argv[i] + strlen(argv[i]) - 1;
+ unit = 1;
+ if((*p >= 'a') && (*p <= 'z')) {
+ if(*p == 'm')
+ unit = 60;
+ else if(*p == 'h')
+ unit = 3600;
+ else if(*p == 'd')
+ unit = 86400;
+ else
+ unit = 1;
+ }
+ opts->renewable = atoi(argv[i] + 6) * unit;
+ }
+ if(!strcmp(argv[i], "forwardable"))
+ opts->forwardable = 1;
+ if(!strcmp(argv[i], "debug"))
+ opts->debug = 1;
+ }
+ return(opts);
+}
+
+static void freeopts(struct options *opts)
+{
+ if(opts->realm != NULL)
+ free(opts->realm);
+ if(opts->instance != NULL)
+ free(opts->instance);
+ if(opts->keytab != NULL)
+ free(opts->keytab);
+ free(opts);
+}
+
+static void freedata(struct data *data)
+{
+ if(data->hascreds)
+ krb5_free_cred_contents(data->ctx, &data->initcreds);
+ if(data->cc != NULL)
+ krb5_cc_close(data->ctx, data->cc);
+ if(data->me != NULL)
+ krb5_free_principal(data->ctx, data->me);
+ if(data->ctx != NULL)
+ krb5_free_context(data->ctx);
+ free(data);
+}
+
+static void cleanupdata(pam_handle_t *pamh, struct data *data, int error_status)
+{
+ freedata(data);
+}
+
+static struct data *getdata(pam_handle_t *pamh, struct options *opts)
+{
+ int ret;
+ struct data *data;
+ char buf[1024];
+ const char *user, *instance;
+ struct passwd *pwent;
+
+ data = NULL;
+ pam_get_data(pamh, "krb5auto-data", (const void **)&data);
+ if(data == NULL) {
+ if(opts->debug)
+ log(LOG_DEBUG, "creating new instance");
+ data = malloc(sizeof(*data));
+ memset(data, 0, sizeof(*data));
+ pam_get_user(pamh, &user, NULL);
+ if(user == NULL) {
+ log(LOG_ERR, "could not get user name");
+ freedata(data);
+ return(NULL);
+ }
+ errno = 0;
+ if((pwent = getpwnam(user)) == NULL) {
+ log(LOG_ERR, "could not user information for `%s': %s", user, (errno == 0)?"user not found":strerror(errno));
+ freedata(data);
+ return(NULL);
+ }
+ data->uid = pwent->pw_uid;
+ data->gid = pwent->pw_gid;
+ if((ret = krb5_init_context(&data->ctx)) != 0) {
+ log(LOG_CRIT, "could not create krb5 context: %s", error_message(ret));
+ freedata(data);
+ return(NULL);
+ }
+ if(opts->instance)
+ instance = opts->instance;
+ else
+ instance = DEF_INSTANCE;
+ if(opts->realm)
+ snprintf(buf, sizeof(buf), "%s/%s@%s", user, instance, opts->realm);
+ else
+ snprintf(buf, sizeof(buf), "%s/%s", user, instance);
+ if((ret = krb5_parse_name(data->ctx, buf, &data->me)) != 0) {
+ log(LOG_ERR, "could not parse principal name `%s': %s", buf, error_message(ret));
+ freedata(data);
+ return(NULL);
+ }
+ pam_set_data(pamh, "krb5auto-data", data, (void (*)(pam_handle_t *, void *, int))cleanupdata);
+ }
+ return(data);
+}
+
+static int savecreds(pam_handle_t *pamh, struct options *opts, struct data *data)
+{
+ int ret, fd;
+ krb5_keytab kt;
+ krb5_get_init_creds_opt icopts;
+ char buf[1024], *ccname, *filename;
+
+ krb5_get_init_creds_opt_init(&icopts);
+ kt = NULL;
+
+ if(opts->keytab) {
+ if((ret = krb5_kt_resolve(data->ctx, opts->keytab, &kt)) != 0) {
+ log(LOG_ERR, "could not resolve keytab `%s': %s", opts->keytab, error_message(ret));
+ ret = PAM_SERVICE_ERR;
+ goto out;
+ }
+ if(opts->debug)
+ log(LOG_DEBUG, "using keytab `%s'", opts->keytab);
+ }
+ krb5_get_init_creds_opt_set_forwardable(&icopts, opts->forwardable);
+ krb5_get_init_creds_opt_set_renew_life(&icopts, opts->renewable);
+ if(data->hascreds) {
+ krb5_free_cred_contents(data->ctx, &data->initcreds);
+ data->hascreds = 0;
+ }
+ if((ret = krb5_get_init_creds_keytab(data->ctx, &data->initcreds, data->me, kt, 0, NULL, &icopts)) != 0) {
+ log(LOG_ERR, "could not get credentials: %s", error_message(ret));
+ ret = PAM_SERVICE_ERR;
+ goto out;
+ }
+ data->hascreds = 1;
+ if(opts->debug)
+ log(LOG_DEBUG, "got creds successfully");
+ snprintf(buf, sizeof(buf), "KRB5CCNAME=FILE:/tmp/krb5cc_%i_XXXXXX", data->uid);
+ ccname = buf + sizeof("KRB5CCNAME=") - 1;
+ filename = ccname + sizeof("FILE:") - 1;
+ if((fd = mkstemp(filename)) < 0) {
+ log(LOG_ERR, "could not create tempfile for credentials cache: %s", strerror(errno));
+ ret = PAM_SERVICE_ERR;
+ goto out;
+ }
+ close(fd);
+ if(opts->debug)
+ log(LOG_DEBUG, "created ccache `%s'", filename);
+ if((ret = krb5_cc_resolve(data->ctx, ccname, &data->cc)) != 0) {
+ log(LOG_ERR, "could not resolve ccache `%s': %s", ccname, error_message(ret));
+ unlink(filename);
+ ret = PAM_SERVICE_ERR;
+ goto out;
+ }
+ if((ret = krb5_cc_initialize(data->ctx, data->cc, data->me)) != 0) {
+ log(LOG_ERR, "could not initialize credentials cache `%s': %s", ccname, error_message(ret));
+ unlink(filename);
+ ret = PAM_SERVICE_ERR;
+ goto out;
+ }
+ if((ret = krb5_cc_store_cred(data->ctx, data->cc, &data->initcreds)) != 0) {
+ log(LOG_ERR, "could not store credentials: %s", error_message(ret));
+ unlink(filename);
+ ret = PAM_SERVICE_ERR;
+ goto out;
+ }
+ chown(filename, data->uid, data->gid);
+ pam_putenv(pamh, strdup(buf));
+ if(opts->debug)
+ log(LOG_DEBUG, "successfully initialized ccache");
+ ret = PAM_SUCCESS;
+
+ out:
+ if(kt != NULL)
+ krb5_kt_close(data->ctx, kt);
+ return(ret);
+}
+
+static int delcreds(pam_handle_t *pamh, struct options *opts, struct data *data)
+{
+ if(opts->debug)
+ log(LOG_DEBUG, "deleting credentials");
+ if(data->hascreds) {
+ krb5_free_cred_contents(data->ctx, &data->initcreds);
+ data->hascreds = 0;
+ if(opts->debug)
+ log(LOG_DEBUG, "freed internal creds");
+ }
+ if(data->cc != NULL) {
+ krb5_cc_destroy(data->ctx, data->cc);
+ data->cc = NULL;
+ if(opts->debug)
+ log(LOG_DEBUG, "destroyed ccache");
+ }
+ return(PAM_SUCCESS);
+}
+
+PAM_EXTERN int pam_sm_authenticate(pam_handle_t *pamh, int flags, int argc, const char **argv)
+{
+ struct options *opts;
+
+ opts = parseopts(argc, argv);
+ if(opts->debug)
+ log(LOG_DEBUG, "pam_sm_authenticate called");
+ freeopts(opts);
+ return(PAM_IGNORE);
+}
+
+PAM_EXTERN int pam_sm_setcred(pam_handle_t *pamh, int flags, int argc, const char **argv)
+{
+ struct options *opts;
+ struct data *data;
+ int ret;
+
+ opts = parseopts(argc, argv);
+ if(opts->debug)
+ log(LOG_DEBUG, "pam_sm_setcred called");
+ data = getdata(pamh, opts);
+ if(data == NULL) {
+ log(LOG_ERR, "could not get data, erroring out");
+ return(PAM_SERVICE_ERR);
+ }
+ ret = PAM_SERVICE_ERR;
+ if(flags & PAM_ESTABLISH_CRED) {
+ ret = savecreds(pamh, opts, data);
+ } else if(flags & PAM_DELETE_CRED) {
+ ret = delcreds(pamh, opts, data);
+ }
+ freeopts(opts);
+ return(ret);
+}
/*
* Local Variables:
- * compile-command: "gcc -Wall -g --shared -fPIC -o pam_krb5auto.so pam_krb5auto.c"
+ * compile-command: "gcc -Wall -g --shared -fPIC -o pam_krb5auto.so pam_krb5auto.c -lkrb5"
* End:
*/
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