selinux-setup: modernizations

Adjustments to match our current coding style, in particular ensures we
always print log messages for unexpected errors.

This changes our code assume mac_selinux_get_create_label_from_exe()
returns a valid label on success. I checked libselinux, this is
guaranteed, and is otherwise relied on in our tree, hence don't do the
pointless check here.

diff --git a/src/core/selinux-setup.c b/src/core/selinux-setup.c
index 39f5edc045e89d5cf7a934321e611e2f19185a7e..f687cfcd53677d0f53e2f1172b381463ae52cac5 100644 (file)
--- a/src/core/selinux-setup.c
+++ b/src/core/selinux-setup.c
@@ -10,6 +10,7 @@
 
 #include "sd-messages.h"
 
+#include "errno-util.h"
 #include "initrd-util.h"
 #include "log.h"
 #include "macro.h"
@@ -26,67 +27,67 @@ static int null_log(int type, const char *fmt, ...) {
 #endif
 
 int mac_selinux_setup(bool *loaded_policy) {
+        assert(loaded_policy);
 
 #if HAVE_SELINUX
-        int enforce = 0;
-        usec_t before_load, after_load;
-        char *con;
         int r;
-        bool initialized;
-
-        assert(loaded_policy);
 
-        /* Turn off all of SELinux' own logging, we want to do that */
+        /* Turn off all of SELinux' own logging, we want to do that ourselves */
         selinux_set_callback(SELINUX_CB_LOG, (const union selinux_callback) { .func_log = null_log });
 
         /* Don't load policy in the initrd if we don't appear to have it.  For the real root, we check below
          * if we've already loaded policy, and return gracefully. */
-        if (in_initrd() && access(selinux_path(), F_OK) < 0)
+        if (in_initrd() && access(selinux_path(), F_OK) < 0) {
+                if (errno != ENOENT)
+                        log_warning_errno(errno, "Unable to check if %s exists, assuming it does not: %m", selinux_path());
+
                 return 0;
+        }
 
-        /* Already initialized by somebody else? */
-        r = getcon_raw(&con);
-        /* getcon_raw can return 0, and still give us a NULL pointer if /proc/self/attr/current is
+        bool initialized = false;
+
+        /* Already initialized by somebody else?
+         *
+         * Note: getcon_raw() can return 0, and still give us a NULL pointer if /proc/self/attr/current is
          * empty. SELinux guarantees this won't happen, but that file isn't specific to SELinux, and may be
          * provided by some other arbitrary LSM with different semantics. */
-        if (r == 0 && con) {
+        _cleanup_freecon_ char *con = NULL;
+        if (getcon_raw(&con) < 0)
+                log_debug_errno(errno, "getcon_raw() failed, assuming SELinux is not initialized: %m");
+        else if (con) {
                 initialized = !streq(con, "kernel");
-                freecon(con);
-        } else
-                initialized = false;
+                log_debug("SELinux already initialized: %s", yes_no(initialized));
+        }
 
-        /* Make sure we have no fds open while loading the policy and
-         * transitioning */
+        /* Make sure we have no fds open while loading the policy and transitioning */
         log_close();
 
         /* Now load the policy */
-        before_load = now(CLOCK_MONOTONIC);
-        r = selinux_init_load_policy(&enforce);
-        if (r == 0) {
-                _cleanup_freecon_ char *label = NULL;
-
+        usec_t before_load = now(CLOCK_MONOTONIC);
+        int enforce = 0;
+        if (selinux_init_load_policy(&enforce) == 0) { /* NB: Apparently doesn't set useful errno! */
                 mac_selinux_retest();
 
                 /* Transition to the new context */
+                _cleanup_freecon_ char *label = NULL;
                 r = mac_selinux_get_create_label_from_exe(SYSTEMD_BINARY_PATH, &label);
-                if (r < 0 || !label) {
+                if (r < 0) {
                         log_open();
-                        log_error("Failed to compute init label, ignoring.");
+                        log_warning_errno(r, "Failed to compute init label, ignoring: %m");
                 } else {
-                        r = setcon_raw(label);
-
+                        r = RET_NERRNO(setcon_raw(label));
                         log_open();
                         if (r < 0)
-                                log_error("Failed to transition into init label '%s', ignoring.", label);
+                                log_warning_errno(r, "Failed to transition into init label '%s', ignoring: %m", label);
+                        else
+                                log_debug("Successfully switched to calculated init label '%s'.", label);
                 }
 
-                after_load = now(CLOCK_MONOTONIC);
-
+                usec_t after_load = now(CLOCK_MONOTONIC);
                 log_info("Successfully loaded SELinux policy in %s.",
                          FORMAT_TIMESPAN(after_load - before_load, 0));
 
                 *loaded_policy = true;
-
         } else {
                 log_open();
 
@@ -96,7 +97,7 @@ int mac_selinux_setup(bool *loaded_policy) {
                                                         LOG_MESSAGE("Failed to load SELinux policy :%m"),
                                                         LOG_MESSAGE_ID(SD_MESSAGE_SELINUX_FAILED_STR));
 
-                        log_warning("Failed to load new SELinux policy. Continuing with old policy.");
+                        log_notice("Failed to load new SELinux policy. Continuing with old policy.");
                 } else
                         log_debug("Unable to load SELinux policy. Ignoring.");
         }