selftests/namespaces: ninth active reference count tests

Test multi-level hierarchy (3+ levels deep).
Grandparent → Parent → Child
When child is active, both parent AND grandparent should be active.

Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-31-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/tools/testing/selftests/namespaces/ns_active_ref_test.c b/tools/testing/selftests/namespaces/ns_active_ref_test.c
index 55a741d32b085e6c21250f4f6fba915ef34082c0..88189398aa35174efac1e14dfe343867e401258e 100644 (file)
--- a/tools/testing/selftests/namespaces/ns_active_ref_test.c
+++ b/tools/testing/selftests/namespaces/ns_active_ref_test.c
@@ -942,4 +942,168 @@ TEST(ns_bind_mount_keeps_in_tree)
        unlink(tmpfile);
 }
 
+/*
+ * Test multi-level hierarchy (3+ levels deep).
+ * Grandparent → Parent → Child
+ * When child is active, both parent AND grandparent should be active.
+ */
+TEST(ns_multilevel_hierarchy)
+{
+       struct file_handle *gp_handle, *p_handle, *c_handle;
+       int ret, pipefd[2];
+       pid_t pid;
+       int status;
+       __u64 gp_id, p_id, c_id;
+       char gp_buf[sizeof(*gp_handle) + MAX_HANDLE_SZ];
+       char p_buf[sizeof(*p_handle) + MAX_HANDLE_SZ];
+       char c_buf[sizeof(*c_handle) + MAX_HANDLE_SZ];
+
+       ASSERT_EQ(pipe(pipefd), 0);
+       pid = fork();
+       ASSERT_GE(pid, 0);
+
+       if (pid == 0) {
+               close(pipefd[0]);
+
+               /* Create grandparent user namespace */
+               if (setup_userns() < 0) {
+                       close(pipefd[1]);
+                       exit(1);
+               }
+
+               int gp_fd = open("/proc/self/ns/user", O_RDONLY);
+               if (gp_fd < 0) {
+                       close(pipefd[1]);
+                       exit(1);
+               }
+               if (ioctl(gp_fd, NS_GET_ID, &gp_id) < 0) {
+                       close(gp_fd);
+                       close(pipefd[1]);
+                       exit(1);
+               }
+               close(gp_fd);
+
+               /* Create parent user namespace */
+               if (setup_userns() < 0) {
+                       close(pipefd[1]);
+                       exit(1);
+               }
+
+               int p_fd = open("/proc/self/ns/user", O_RDONLY);
+               if (p_fd < 0) {
+                       close(pipefd[1]);
+                       exit(1);
+               }
+               if (ioctl(p_fd, NS_GET_ID, &p_id) < 0) {
+                       close(p_fd);
+                       close(pipefd[1]);
+                       exit(1);
+               }
+               close(p_fd);
+
+               /* Create child user namespace */
+               if (setup_userns() < 0) {
+                       close(pipefd[1]);
+                       exit(1);
+               }
+
+               int c_fd = open("/proc/self/ns/user", O_RDONLY);
+               if (c_fd < 0) {
+                       close(pipefd[1]);
+                       exit(1);
+               }
+               if (ioctl(c_fd, NS_GET_ID, &c_id) < 0) {
+                       close(c_fd);
+                       close(pipefd[1]);
+                       exit(1);
+               }
+               close(c_fd);
+
+               /* Send all three namespace IDs */
+               write(pipefd[1], &gp_id, sizeof(gp_id));
+               write(pipefd[1], &p_id, sizeof(p_id));
+               write(pipefd[1], &c_id, sizeof(c_id));
+               close(pipefd[1]);
+               exit(0);
+       }
+
+       close(pipefd[1]);
+
+       /* Read all three namespace IDs - fixed size, no parsing needed */
+       ret = read(pipefd[0], &gp_id, sizeof(gp_id));
+       if (ret != sizeof(gp_id)) {
+               close(pipefd[0]);
+               waitpid(pid, NULL, 0);
+               SKIP(return, "Failed to read grandparent namespace ID from child");
+       }
+
+       ret = read(pipefd[0], &p_id, sizeof(p_id));
+       if (ret != sizeof(p_id)) {
+               close(pipefd[0]);
+               waitpid(pid, NULL, 0);
+               SKIP(return, "Failed to read parent namespace ID from child");
+       }
+
+       ret = read(pipefd[0], &c_id, sizeof(c_id));
+       close(pipefd[0]);
+       if (ret != sizeof(c_id)) {
+               waitpid(pid, NULL, 0);
+               SKIP(return, "Failed to read child namespace ID from child");
+       }
+
+       /* Construct file handles from namespace IDs */
+       gp_handle = (struct file_handle *)gp_buf;
+       gp_handle->handle_bytes = sizeof(struct nsfs_file_handle);
+       gp_handle->handle_type = FILEID_NSFS;
+       struct nsfs_file_handle *gp_fh = (struct nsfs_file_handle *)gp_handle->f_handle;
+       gp_fh->ns_id = gp_id;
+       gp_fh->ns_type = 0;
+       gp_fh->ns_inum = 0;
+
+       p_handle = (struct file_handle *)p_buf;
+       p_handle->handle_bytes = sizeof(struct nsfs_file_handle);
+       p_handle->handle_type = FILEID_NSFS;
+       struct nsfs_file_handle *p_fh = (struct nsfs_file_handle *)p_handle->f_handle;
+       p_fh->ns_id = p_id;
+       p_fh->ns_type = 0;
+       p_fh->ns_inum = 0;
+
+       c_handle = (struct file_handle *)c_buf;
+       c_handle->handle_bytes = sizeof(struct nsfs_file_handle);
+       c_handle->handle_type = FILEID_NSFS;
+       struct nsfs_file_handle *c_fh = (struct nsfs_file_handle *)c_handle->f_handle;
+       c_fh->ns_id = c_id;
+       c_fh->ns_type = 0;
+       c_fh->ns_inum = 0;
+
+       /* Open child before process exits */
+       int c_fd = open_by_handle_at(FD_NSFS_ROOT, c_handle, O_RDONLY);
+       if (c_fd < 0) {
+               waitpid(pid, NULL, 0);
+               SKIP(return, "Failed to open child namespace");
+       }
+
+       waitpid(pid, &status, 0);
+       ASSERT_TRUE(WIFEXITED(status));
+       ASSERT_EQ(WEXITSTATUS(status), 0);
+
+       /*
+        * With 3-level hierarchy and child active:
+        * - Child is active (we hold fd)
+        * - Parent should be active (propagated from child)
+        * - Grandparent should be active (propagated from parent)
+        */
+       TH_LOG("Testing parent active when child is active");
+       int p_fd = open_by_handle_at(FD_NSFS_ROOT, p_handle, O_RDONLY);
+       ASSERT_GE(p_fd, 0);
+
+       TH_LOG("Testing grandparent active when child is active");
+       int gp_fd = open_by_handle_at(FD_NSFS_ROOT, gp_handle, O_RDONLY);
+       ASSERT_GE(gp_fd, 0);
+
+       close(c_fd);
+       close(p_fd);
+       close(gp_fd);
+}
+
 TEST_HARNESS_MAIN