1 files changed, 113 insertions, 0 deletions
diff --git a/src/shared/pam-util.c b/src/shared/pam-util.c
new file mode 100644
index 0000000..d7a5046
--- /dev/null
+++ b/src/shared/pam-util.c
@@ -0,0 +1,113 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <security/pam_ext.h>
+#include <syslog.h>
+#include <stdlib.h>
+
+#include "alloc-util.h"
+#include "errno-util.h"
+#include "macro.h"
+#include "pam-util.h"
+#include "stdio-util.h"
+#include "string-util.h"
+
+int pam_syslog_errno(pam_handle_t *handle, int level, int error, const char *format, ...) {
+        va_list ap;
+
+        LOCAL_ERRNO(error);
+
+        va_start(ap, format);
+        pam_vsyslog(handle, LOG_ERR, format, ap);
+        va_end(ap);
+
+        return error == -ENOMEM ? PAM_BUF_ERR : PAM_SERVICE_ERR;
+}
+
+int pam_syslog_pam_error(pam_handle_t *handle, int level, int error, const char *format, ...) {
+        /* This wraps pam_syslog() but will replace @PAMERR@ with a string from pam_strerror().
+         * @PAMERR@ must be at the very end. */
+
+        va_list ap;
+        va_start(ap, format);
+
+        const char *p = endswith(format, "@PAMERR@");
+        if (p) {
+                const char *pamerr = pam_strerror(handle, error);
+                if (strchr(pamerr, '%'))
+                        pamerr = "n/a";  /* We cannot have any formatting chars */
+
+                char buf[p - format + strlen(pamerr) + 1];
+                xsprintf(buf, "%.*s%s", (int)(p - format), format, pamerr);
+
+                DISABLE_WARNING_FORMAT_NONLITERAL;
+                pam_vsyslog(handle, level, buf, ap);
+                REENABLE_WARNING;
+        } else
+                pam_vsyslog(handle, level, format, ap);
+
+        va_end(ap);
+
+        return error;
+}
+
+static void cleanup_system_bus(pam_handle_t *handle, void *data, int error_status) {
+        sd_bus_flush_close_unref(data);
+}
+
+int pam_acquire_bus_connection(pam_handle_t *handle, const char *module_name, sd_bus **ret) {
+        _cleanup_(sd_bus_unrefp) sd_bus *bus = NULL;
+        _cleanup_free_ char *cache_id = NULL;
+        int r;
+
+        assert(handle);
+        assert(module_name);
+        assert(ret);
+
+        cache_id = strjoin("system-bus-", module_name);
+        if (!cache_id)
+                return pam_log_oom(handle);
+
+        /* We cache the bus connection so that we can share it between the session and the authentication hooks */
+        r = pam_get_data(handle, cache_id, (const void**) &bus);
+        if (r == PAM_SUCCESS && bus) {
+                *ret = sd_bus_ref(TAKE_PTR(bus)); /* Increase the reference counter, so that the PAM data stays valid */
+                return PAM_SUCCESS;
+        }
+        if (!IN_SET(r, PAM_SUCCESS, PAM_NO_MODULE_DATA))
+                return pam_syslog_pam_error(handle, LOG_ERR, r, "Failed to get bus connection: @PAMERR@");
+
+        r = sd_bus_open_system(&bus);
+        if (r < 0)
+                return pam_syslog_errno(handle, LOG_ERR, r, "Failed to connect to system bus: %m");
+
+        r = pam_set_data(handle, cache_id, bus, cleanup_system_bus);
+        if (r != PAM_SUCCESS)
+                return pam_syslog_pam_error(handle, LOG_ERR, r, "Failed to set PAM bus data: @PAMERR@");
+
+        sd_bus_ref(bus);
+        *ret = TAKE_PTR(bus);
+
+        return PAM_SUCCESS;
+}
+
+int pam_release_bus_connection(pam_handle_t *handle, const char *module_name) {
+        _cleanup_free_ char *cache_id = NULL;
+        int r;
+
+        assert(module_name);
+
+        cache_id = strjoin("system-bus-", module_name);
+        if (!cache_id)
+                return pam_log_oom(handle);
+
+        r = pam_set_data(handle, cache_id, NULL, NULL);
+        if (r != PAM_SUCCESS)
+                return pam_syslog_pam_error(handle, LOG_ERR, r, "Failed to release PAM user record data: @PAMERR@");
+
+        return PAM_SUCCESS;
+}
+
+void pam_cleanup_free(pam_handle_t *handle, void *data, int error_status) {
+        /* A generic destructor for pam_set_data() that just frees the specified data */
+        free(data);
+}