selftests/namespaces: fifteenth active reference count tests

Test different namespace types (net, uts, ipc) all contributing
active references to the same owning user namespace.

Link: https://patch.msgid.link/[e-mail]
Reviewed-by: Jeff Layton <[e-mail]>
Signed-off-by: Christian Brauner <[e-mail]>

tools/testing/selftests/namespaces/ns_active_ref_test.c

···
 	ASSERT_LT(ua_fd, 0);
 }
 
+/*
+ * Test different namespace types (net, uts, ipc) all contributing
+ * active references to the same owning user namespace.
+ */
+TEST(ns_mixed_types_same_owner)
+{
+	struct file_handle *user_handle, *net_handle, *uts_handle;
+	int ret, pipefd[2];
+	pid_t pid;
+	int status;
+	__u64 u_id, n_id, ut_id;
+	char u_buf[sizeof(*user_handle) + MAX_HANDLE_SZ];
+	char n_buf[sizeof(*net_handle) + MAX_HANDLE_SZ];
+	char ut_buf[sizeof(*uts_handle) + MAX_HANDLE_SZ];
+
+	ASSERT_EQ(pipe(pipefd), 0);
+	pid = fork();
+	ASSERT_GE(pid, 0);
+
+	if (pid == 0) {
+		close(pipefd[0]);
+
+		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);
+
+		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);
+
+		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 */
+	user_handle = (struct file_handle *)u_buf;
+	user_handle->handle_bytes = sizeof(struct nsfs_file_handle);
+	user_handle->handle_type = FILEID_NSFS;
+	struct nsfs_file_handle *u_fh = (struct nsfs_file_handle *)user_handle->f_handle;
+	u_fh->ns_id = u_id;
+	u_fh->ns_type = 0;
+	u_fh->ns_inum = 0;
+
+	net_handle = (struct file_handle *)n_buf;
+	net_handle->handle_bytes = sizeof(struct nsfs_file_handle);
+	net_handle->handle_type = FILEID_NSFS;
+	struct nsfs_file_handle *n_fh = (struct nsfs_file_handle *)net_handle->f_handle;
+	n_fh->ns_id = n_id;
+	n_fh->ns_type = 0;
+	n_fh->ns_inum = 0;
+
+	uts_handle = (struct file_handle *)ut_buf;
+	uts_handle->handle_bytes = sizeof(struct nsfs_file_handle);
+	uts_handle->handle_type = FILEID_NSFS;
+	struct nsfs_file_handle *ut_fh = (struct nsfs_file_handle *)uts_handle->f_handle;
+	ut_fh->ns_id = ut_id;
+	ut_fh->ns_type = 0;
+	ut_fh->ns_inum = 0;
+
+	/* Open both non-user namespaces */
+	int n_fd = open_by_handle_at(FD_NSFS_ROOT, net_handle, O_RDONLY);
+	int ut_fd = open_by_handle_at(FD_NSFS_ROOT, uts_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));
+	ASSERT_EQ(WEXITSTATUS(status), 0);
+
+	/* User namespace should be active (2 active children) */
+	TH_LOG("Both net and uts active - user ns should be active");
+	int u_fd = open_by_handle_at(FD_NSFS_ROOT, user_handle, O_RDONLY);
+	ASSERT_GE(u_fd, 0);
+	close(u_fd);
+
+	/* Close net - user ns should STILL be active (uts still active) */
+	TH_LOG("Closing net - user ns should still be active");
+	close(n_fd);
+	u_fd = open_by_handle_at(FD_NSFS_ROOT, user_handle, O_RDONLY);
+	ASSERT_GE(u_fd, 0);
+	close(u_fd);
+
+	/* Close uts - user ns should become inactive */
+	TH_LOG("Closing uts - user ns should become inactive");
+	close(ut_fd);
+	u_fd = open_by_handle_at(FD_NSFS_ROOT, user_handle, O_RDONLY);
+	ASSERT_LT(u_fd, 0);
+}
+
 TEST_HARNESS_MAIN