selftests/fsmount_ns: add missing TARGETS and fix cap test

Add missing top-level kselftest TARGETS entries for empty_mntns and
fsmount_ns so that 'make kselftest' discovers and runs these tests.

Fix requires_cap_sys_admin test which always SKIPped because fsopen()
was called after enter_userns(), where CAP_SYS_ADMIN in the mount
namespace's user_ns is unavailable. Move fsopen/fsconfig before fork so
the configured fs_fd is inherited by the child, which then only needs to
call fsmount() after dropping privileges.

Fixes: 3ac7ea91f3d0 ("selftests: add FSMOUNT_NAMESPACE tests")
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 2d05b3e1a26e205dc8bda868a404c107b8cfd657..5677dd8b2a768e76cff23eda7c407f91b1333f9d 100644 (file)
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -39,6 +39,8 @@ TARGETS += filesystems/statmount
 TARGETS += filesystems/mount-notify
 TARGETS += filesystems/fuse
 TARGETS += filesystems/move_mount
+TARGETS += filesystems/empty_mntns
+TARGETS += filesystems/fsmount_ns
 TARGETS += firmware
 TARGETS += fpu
 TARGETS += ftrace

diff --git a/tools/testing/selftests/filesystems/fsmount_ns/fsmount_ns_test.c b/tools/testing/selftests/filesystems/fsmount_ns/fsmount_ns_test.c
index 239abbe638149064c4f350e71bb264c7d57cba02..b70b3051eed48faab1e4413de3a2b1575c013baf 100644 (file)
--- a/tools/testing/selftests/filesystems/fsmount_ns/fsmount_ns_test.c
+++ b/tools/testing/selftests/filesystems/fsmount_ns/fsmount_ns_test.c
@@ -388,12 +388,23 @@ TEST_F(fsmount_ns_caps, requires_cap_sys_admin)
 {
        pid_t pid;
        int status;
+       int fs_fd;
+
+       /*
+        * Prepare the configured filesystem fd as root before forking.
+        * fsopen() requires CAP_SYS_ADMIN in the mount namespace's
+        * user_ns, which won't be available after enter_userns().
+        */
+       fs_fd = sys_fsopen("tmpfs", FSOPEN_CLOEXEC);
+       ASSERT_GE(fs_fd, 0);
+
+       ASSERT_EQ(sys_fsconfig(fs_fd, FSCONFIG_CMD_CREATE, NULL, NULL, 0), 0);
 
        pid = fork();
        ASSERT_GE(pid, 0);
 
        if (pid == 0) {
-               int fs_fd, fd;
+               int fd;
 
                /* Child: drop privileges using utils.h helper */
                if (enter_userns() != 0)
@@ -403,15 +414,6 @@ TEST_F(fsmount_ns_caps, requires_cap_sys_admin)
                if (caps_down() == 0)
                        _exit(3);
 
-               fs_fd = sys_fsopen("tmpfs", FSOPEN_CLOEXEC);
-               if (fs_fd < 0)
-                       _exit(4);
-
-               if (sys_fsconfig(fs_fd, FSCONFIG_CMD_CREATE, NULL, NULL, 0) < 0) {
-                       close(fs_fd);
-                       _exit(5);
-               }
-
                fd = sys_fsmount(fs_fd, FSMOUNT_NAMESPACE | FSMOUNT_CLOEXEC, 0);
                close(fs_fd);
 
@@ -432,6 +434,7 @@ TEST_F(fsmount_ns_caps, requires_cap_sys_admin)
                _exit(7);
        }
 
+       close(fs_fd);
        ASSERT_EQ(waitpid(pid, &status, 0), pid);
        ASSERT_TRUE(WIFEXITED(status));
 
@@ -448,12 +451,6 @@ TEST_F(fsmount_ns_caps, requires_cap_sys_admin)
        case 3:
                SKIP(return, "caps_down failed");
                break;
-       case 4:
-               SKIP(return, "fsopen failed in userns");
-               break;
-       case 5:
-               SKIP(return, "fsconfig CMD_CREATE failed in userns");
-               break;
        case 6:
                SKIP(return, "FSMOUNT_NAMESPACE not supported");
                break;