Merge pull request #25666 from poettering/selinux-getconf-fixup

selinux getXYZcon() NULL return fixes

src/core/selinux-access.c

@@ -229,9 +229,7 @@ int mac_selinux_access_check_internal(
         } else {
                 /* If no unit context is known, use our own */
                 if (getcon_raw(&fcon) < 0) {
-                        r = -errno;
-
-                        log_warning_errno(r, "SELinux getcon_raw() failed%s (perm=%s): %m",
+                        log_warning_errno(errno, "SELinux getcon_raw() failed%s (perm=%s): %m",
                                           enforce ? "" : ", ignoring",
                                           permission);
                         if (!enforce)
@@ -239,6 +237,12 @@ int mac_selinux_access_check_internal(
 
                         return sd_bus_error_setf(error, SD_BUS_ERROR_ACCESS_DENIED, "Failed to get current context: %m");
                 }
+                if (!fcon) {
+                        if (!enforce)
+                                return 0;
+
+                        return sd_bus_error_setf(error, SD_BUS_ERROR_ACCESS_DENIED, "We appear not to have any SELinux context: %m");
+                }
 
                 acon = fcon;
                 tclass = "system";

src/core/selinux-setup.c

@@ -30,30 +30,28 @@ int mac_selinux_setup(bool *loaded_policy) {
         usec_t before_load, after_load;
         char *con;
         int r;
-        bool initialized = false;
+        bool initialized;
 
         assert(loaded_policy);
 
         /* Turn off all of SELinux' own logging, we want to do that */
-        selinux_set_callback(SELINUX_CB_LOG, (union selinux_callback) { .func_log = null_log });
+        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.
-         */
+        /* 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)
                 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 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. */
+        /* 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) {
                 initialized = !streq(con, "kernel");
                 freecon(con);
-        }
+        } else
+                initialized = false;
 
         /* Make sure we have no fds open while loading the policy and
          * transitioning */

src/shared/selinux-util.c

@@ -277,7 +277,7 @@ static int selinux_fix_fd(
                         return 0;
 
                 /* If the old label is identical to the new one, suppress any kind of error */
-                if (getfilecon_raw(FORMAT_PROC_FD_PATH(fd), &oldcon) >= 0 && streq(fcon, oldcon))
+                if (getfilecon_raw(FORMAT_PROC_FD_PATH(fd), &oldcon) >= 0 && streq_ptr(fcon, oldcon))
                         return 0;
 
                 return log_enforcing_errno(r, "Unable to fix SELinux security context of %s: %m", label_path);
@@ -381,9 +381,13 @@ int mac_selinux_get_create_label_from_exe(const char *exe, char **label) {
 
         if (getcon_raw(&mycon) < 0)
                 return -errno;
+        if (!mycon)
+                return -EOPNOTSUPP;
 
         if (getfilecon_raw(exe, &fcon) < 0)
                 return -errno;
+        if (!fcon)
+                return -EOPNOTSUPP;
 
         sclass = string_to_security_class("process");
         if (sclass == 0)
@@ -395,14 +399,21 @@ int mac_selinux_get_create_label_from_exe(const char *exe, char **label) {
 #endif
 }
 
-int mac_selinux_get_our_label(char **label) {
-#if HAVE_SELINUX
-        assert(label);
+int mac_selinux_get_our_label(char **ret) {
+        assert(ret);
 
+#if HAVE_SELINUX
         if (!mac_selinux_use())
                 return -EOPNOTSUPP;
 
-        return RET_NERRNO(getcon_raw(label));
+        _cleanup_freecon_ char *con = NULL;
+        if (getcon_raw(&con) < 0)
+                return -errno;
+        if (!con)
+                return -EOPNOTSUPP;
+
+        *ret = TAKE_PTR(con);
+        return 0;
 #else
         return -EOPNOTSUPP;
 #endif
@@ -424,13 +435,20 @@ int mac_selinux_get_child_mls_label(int socket_fd, const char *exe, const char *
 
         if (getcon_raw(&mycon) < 0)
                 return -errno;
+        if (!mycon)
+                return -EOPNOTSUPP;
 
         if (getpeercon_raw(socket_fd, &peercon) < 0)
                 return -errno;
+        if (!peercon)
+                return -EOPNOTSUPP;
 
-        if (!exec_label) /* If there is no context set for next exec let's use context of target executable */
+        if (!exec_label) { /* If there is no context set for next exec let's use context of target executable */
                 if (getfilecon_raw(exe, &fcon) < 0)
                         return -errno;
+                if (!fcon)
+                        return -EOPNOTSUPP;
+        }
 
         bcon = context_new(mycon);
         if (!bcon)