test: do not fail network namespace test with permission issues

When running in LXC with AppArmor we'll most likely get an error when creating
a network namespace due to a kernel regression in < v6.2 affecting AppArmor,
resulting in denials. Like other tests, avoid failing in case of permission
issues and handle it gracefully.

(cherry picked from commit 6ab21f2)
(cherry picked from commit ff35460)
(cherry picked from commit c3aa100)

Author: bluca

src/test/test-namespace.c

@@ -1,6 +1,7 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
 #include <fcntl.h>
+#include <sysexits.h>
 #include <sys/socket.h>
 #include <sys/stat.h>
 
@@ -84,6 +85,7 @@ TEST(tmpdir) {
 
 static void test_shareable_ns(unsigned long nsflag) {
         _cleanup_close_pair_ int s[2] = PIPE_EBADF;
+        bool permission_denied = false;
         pid_t pid1, pid2, pid3;
         int r, n = 0;
         siginfo_t si;
@@ -100,42 +102,56 @@ static void test_shareable_ns(unsigned long nsflag) {
 
         if (pid1 == 0) {
                 r = setup_shareable_ns(s, nsflag);
-                assert_se(r >= 0);
-                _exit(r);
+                assert_se(r >= 0 || ERRNO_IS_PRIVILEGE(r));
+                _exit(r >= 0 ? r : EX_NOPERM);
         }
 
         pid2 = fork();
         assert_se(pid2 >= 0);
 
         if (pid2 == 0) {
                 r = setup_shareable_ns(s, nsflag);
-                assert_se(r >= 0);
-                exit(r);
+                assert_se(r >= 0 || ERRNO_IS_PRIVILEGE(r));
+                _exit(r >= 0 ? r : EX_NOPERM);
         }
 
         pid3 = fork();
         assert_se(pid3 >= 0);
 
         if (pid3 == 0) {
                 r = setup_shareable_ns(s, nsflag);
-                assert_se(r >= 0);
-                exit(r);
+                assert_se(r >= 0 || ERRNO_IS_PRIVILEGE(r));
+                _exit(r >= 0 ? r : EX_NOPERM);
         }
 
         r = wait_for_terminate(pid1, &si);
         assert_se(r >= 0);
         assert_se(si.si_code == CLD_EXITED);
-        n += si.si_status;
+        if (si.si_status == EX_NOPERM)
+                permission_denied = true;
+        else
+                n += si.si_status;
 
         r = wait_for_terminate(pid2, &si);
         assert_se(r >= 0);
         assert_se(si.si_code == CLD_EXITED);
-        n += si.si_status;
+        if (si.si_status == EX_NOPERM)
+                permission_denied = true;
+        else
+                n += si.si_status;
 
         r = wait_for_terminate(pid3, &si);
         assert_se(r >= 0);
         assert_se(si.si_code == CLD_EXITED);
-        n += si.si_status;
+        if (si.si_status == EX_NOPERM)
+                permission_denied = true;
+        else
+                n += si.si_status;
+
+        /* LSMs can cause setup_shareable_ns() to fail with permission denied, do not fail the test in that
+         * case (e.g.: LXC with AppArmor on kernel < v6.2). */
+        if (permission_denied)
+                return (void) log_tests_skipped("insufficient privileges");
 
         assert_se(n == 1);
 }