Test that different namespace types with same owner all contribute
active references to the owning user namespace.

Signed-off-by: Christian Brauner <brauner@kernel.org>
---
 .../selftests/namespaces/ns_active_ref_test.c      | 178 +++++++++++++++++++++
 1 file changed, 178 insertions(+)

diff --git a/tools/testing/selftests/namespaces/ns_active_ref_test.c b/tools/testing/selftests/namespaces/ns_active_ref_test.c
index 15d001df981c..3c2f99b25067 100644
--- a/tools/testing/selftests/namespaces/ns_active_ref_test.c
+++ b/tools/testing/selftests/namespaces/ns_active_ref_test.c
@@ -1353,4 +1353,182 @@ TEST(ns_multiple_children_same_parent)
 	}
 }
 
+/*
+ * Test that different namespace types with same owner all contribute
+ * active references to the owning user namespace.
+ */
+TEST(ns_different_types_same_owner)
+{
+	struct file_handle *u_handle, *n_handle, *ut_handle;
+	int ret, pipefd[2];
+	pid_t pid;
+	int status;
+	__u64 u_id, n_id, ut_id;
+	char u_buf[sizeof(*u_handle) + MAX_HANDLE_SZ];
+	char n_buf[sizeof(*n_handle) + MAX_HANDLE_SZ];
+	char ut_buf[sizeof(*ut_handle) + MAX_HANDLE_SZ];
+
+	ASSERT_EQ(pipe(pipefd), 0);
+	pid = fork();
+	ASSERT_GE(pid, 0);
+
+	if (pid == 0) {
+		close(pipefd[0]);
+
+		/* Create user namespace */
+		if (setup_userns() < 0) {
+			close(pipefd[1]);
+			exit(1);
+		}
+
+		int u_fd = open("/proc/self/ns/user", O_RDONLY);
+		if (u_fd < 0) {
+			close(pipefd[1]);
+			exit(1);
+		}
+		if (ioctl(u_fd, NS_GET_ID, &u_id) < 0) {
+			close(u_fd);
+			close(pipefd[1]);
+			exit(1);
+		}
+		close(u_fd);
+
+		/* Create network namespace (owned by user namespace) */
+		if (unshare(CLONE_NEWNET) < 0) {
+			close(pipefd[1]);
+			exit(1);
+		}
+
+		int n_fd = open("/proc/self/ns/net", O_RDONLY);
+		if (n_fd < 0) {
+			close(pipefd[1]);
+			exit(1);
+		}
+		if (ioctl(n_fd, NS_GET_ID, &n_id) < 0) {
+			close(n_fd);
+			close(pipefd[1]);
+			exit(1);
+		}
+		close(n_fd);
+
+		/* Create UTS namespace (also owned by user namespace) */
+		if (unshare(CLONE_NEWUTS) < 0) {
+			close(pipefd[1]);
+			exit(1);
+		}
+
+		int ut_fd = open("/proc/self/ns/uts", O_RDONLY);
+		if (ut_fd < 0) {
+			close(pipefd[1]);
+			exit(1);
+		}
+		if (ioctl(ut_fd, NS_GET_ID, &ut_id) < 0) {
+			close(ut_fd);
+			close(pipefd[1]);
+			exit(1);
+		}
+		close(ut_fd);
+
+		/* Send all namespace IDs */
+		write(pipefd[1], &u_id, sizeof(u_id));
+		write(pipefd[1], &n_id, sizeof(n_id));
+		write(pipefd[1], &ut_id, sizeof(ut_id));
+		close(pipefd[1]);
+		exit(0);
+	}
+
+	close(pipefd[1]);
+
+	/* Read all three namespace IDs - fixed size, no parsing needed */
+	ret = read(pipefd[0], &u_id, sizeof(u_id));
+	if (ret != sizeof(u_id)) {
+		close(pipefd[0]);
+		waitpid(pid, NULL, 0);
+		SKIP(return, "Failed to read user namespace ID");
+	}
+
+	ret = read(pipefd[0], &n_id, sizeof(n_id));
+	if (ret != sizeof(n_id)) {
+		close(pipefd[0]);
+		waitpid(pid, NULL, 0);
+		SKIP(return, "Failed to read network namespace ID");
+	}
+
+	ret = read(pipefd[0], &ut_id, sizeof(ut_id));
+	close(pipefd[0]);
+	if (ret != sizeof(ut_id)) {
+		waitpid(pid, NULL, 0);
+		SKIP(return, "Failed to read UTS namespace ID");
+	}
+
+	/* Construct file handles from namespace IDs */
+	u_handle = (struct file_handle *)u_buf;
+	u_handle->handle_bytes = sizeof(struct nsfs_file_handle);
+	u_handle->handle_type = FILEID_NSFS;
+	struct nsfs_file_handle *u_fh = (struct nsfs_file_handle *)u_handle->f_handle;
+	u_fh->ns_id = u_id;
+	u_fh->ns_type = 0;
+	u_fh->ns_inum = 0;
+
+	n_handle = (struct file_handle *)n_buf;
+	n_handle->handle_bytes = sizeof(struct nsfs_file_handle);
+	n_handle->handle_type = FILEID_NSFS;
+	struct nsfs_file_handle *n_fh = (struct nsfs_file_handle *)n_handle->f_handle;
+	n_fh->ns_id = n_id;
+	n_fh->ns_type = 0;
+	n_fh->ns_inum = 0;
+
+	ut_handle = (struct file_handle *)ut_buf;
+	ut_handle->handle_bytes = sizeof(struct nsfs_file_handle);
+	ut_handle->handle_type = FILEID_NSFS;
+	struct nsfs_file_handle *ut_fh = (struct nsfs_file_handle *)ut_handle->f_handle;
+	ut_fh->ns_id = ut_id;
+	ut_fh->ns_type = 0;
+	ut_fh->ns_inum = 0;
+
+	/* Open both non-user namespaces before process exits */
+	int n_fd = open_by_handle_at(FD_NSFS_ROOT, n_handle, O_RDONLY);
+	int ut_fd = open_by_handle_at(FD_NSFS_ROOT, ut_handle, O_RDONLY);
+
+	if (n_fd < 0 || ut_fd < 0) {
+		if (n_fd >= 0) close(n_fd);
+		if (ut_fd >= 0) close(ut_fd);
+		waitpid(pid, NULL, 0);
+		SKIP(return, "Failed to open namespaces");
+	}
+
+	waitpid(pid, &status, 0);
+	ASSERT_TRUE(WIFEXITED(status));
+	if (WEXITSTATUS(status) != 0) {
+		close(n_fd);
+		close(ut_fd);
+		SKIP(return, "Child failed");
+	}
+
+	/*
+	 * Both network and UTS namespaces are active.
+	 * User namespace should be active (gets 2 active refs).
+	 */
+	TH_LOG("Both net and uts active - user namespace should be active");
+	int u_fd = open_by_handle_at(FD_NSFS_ROOT, u_handle, O_RDONLY);
+	ASSERT_GE(u_fd, 0);
+	close(u_fd);
+
+	/* Close network namespace - user namespace should STILL be active */
+	TH_LOG("Closing network ns - user ns should still be active (uts still active)");
+	close(n_fd);
+	u_fd = open_by_handle_at(FD_NSFS_ROOT, u_handle, O_RDONLY);
+	ASSERT_GE(u_fd, 0);
+	close(u_fd);
+
+	/* Close UTS namespace - user namespace should become inactive */
+	TH_LOG("Closing uts ns - user ns should become inactive");
+	close(ut_fd);
+	u_fd = open_by_handle_at(FD_NSFS_ROOT, u_handle, O_RDONLY);
+	if (u_fd >= 0) {
+		close(u_fd);
+		TH_LOG("Warning: User namespace still active after all owned namespaces inactive");
+	}
+}
+
 TEST_HARNESS_MAIN

-- 
2.47.3