+#define DEF_INSTANCE "autologin"
+
+struct options
+{
+ char *realm;
+ char *instance;
+ char *keytab;
+ int debug;
+};
+
+struct data
+{
+ krb5_context ctx;
+ krb5_ccache cc;
+ krb5_principal me;
+};
+
+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;
+
+ 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(!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->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;
+
+ 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));
+ if((ret = krb5_init_context(&data->ctx)) != 0) {
+ log(LOG_CRIT, "could not create krb5 context: %s", error_message(ret));
+ freedata(data);
+ return(NULL);
+ }
+ pam_get_user(pamh, &user, 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 void savecreds(struct options *opts, struct data *data)
+{
+}
+
+PAM_EXTERN int pam_sm_authenticate(pam_handle_t *pamh, int flags, int argc, const char **argv)
+{
+ 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;
+
+ opts = parseopts(argc, argv);
+ data = getdata(pamh, opts);
+ if(data == NULL) {
+ log(LOG_ERR, "could not get data, erroring out");
+ return(PAM_SERVICE_ERR);
+ }
+ if(flags & PAM_ESTABLISH_CRED) {
+ savecreds(opts, data);
+ }
+ freeopts(opts);
+ return(PAM_IGNORE);
+}