selftests/namespaces: eigth listns() test

Test that hierarchical active reference propagation keeps parent
user namespaces visible in listns().

Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-46-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/tools/testing/selftests/namespaces/listns_test.c b/tools/testing/selftests/namespaces/listns_test.c
index d73c2a2898cf3011952a91f2aab033017cc3ccb9..d3be6f97d34e5d3a34b7b62ac4394a99f4238586 100644 (file)
--- a/tools/testing/selftests/namespaces/listns_test.c
+++ b/tools/testing/selftests/namespaces/listns_test.c
@@ -477,4 +477,154 @@ TEST(listns_multiple_types)
                TH_LOG("  [%zd] ns_id: %llu", i, (unsigned long long)ns_ids[i]);
 }
 
+/*
+ * Test that hierarchical active reference propagation keeps parent
+ * user namespaces visible in listns().
+ */
+TEST(listns_hierarchical_visibility)
+{
+       struct ns_id_req req = {
+               .size = sizeof(req),
+               .spare = 0,
+               .ns_id = 0,
+               .ns_type = CLONE_NEWUSER,
+               .spare2 = 0,
+               .user_ns_id = 0,
+       };
+       __u64 parent_ns_id = 0, child_ns_id = 0;
+       int sv[2];
+       pid_t pid;
+       int status;
+       int bytes;
+       __u64 ns_ids[100];
+       ssize_t ret;
+       bool found_parent, found_child;
+
+       ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, sv), 0);
+
+       pid = fork();
+       ASSERT_GE(pid, 0);
+
+       if (pid == 0) {
+               int fd;
+               char buf;
+
+               close(sv[0]);
+
+               /* Create parent user namespace */
+               if (setup_userns() < 0) {
+                       close(sv[1]);
+                       exit(1);
+               }
+
+               fd = open("/proc/self/ns/user", O_RDONLY);
+               if (fd < 0) {
+                       close(sv[1]);
+                       exit(1);
+               }
+
+               if (ioctl(fd, NS_GET_ID, &parent_ns_id) < 0) {
+                       close(fd);
+                       close(sv[1]);
+                       exit(1);
+               }
+               close(fd);
+
+               /* Create child user namespace */
+               if (setup_userns() < 0) {
+                       close(sv[1]);
+                       exit(1);
+               }
+
+               fd = open("/proc/self/ns/user", O_RDONLY);
+               if (fd < 0) {
+                       close(sv[1]);
+                       exit(1);
+               }
+
+               if (ioctl(fd, NS_GET_ID, &child_ns_id) < 0) {
+                       close(fd);
+                       close(sv[1]);
+                       exit(1);
+               }
+               close(fd);
+
+               /* Send both IDs to parent */
+               if (write(sv[1], &parent_ns_id, sizeof(parent_ns_id)) != sizeof(parent_ns_id)) {
+                       close(sv[1]);
+                       exit(1);
+               }
+               if (write(sv[1], &child_ns_id, sizeof(child_ns_id)) != sizeof(child_ns_id)) {
+                       close(sv[1]);
+                       exit(1);
+               }
+
+               /* Wait for parent signal */
+               if (read(sv[1], &buf, 1) != 1) {
+                       close(sv[1]);
+                       exit(1);
+               }
+               close(sv[1]);
+               exit(0);
+       }
+
+       /* Parent */
+       close(sv[1]);
+
+       /* Read both namespace IDs */
+       bytes = read(sv[0], &parent_ns_id, sizeof(parent_ns_id));
+       bytes += read(sv[0], &child_ns_id, sizeof(child_ns_id));
+
+       if (bytes != (int)(2 * sizeof(__u64))) {
+               close(sv[0]);
+               kill(pid, SIGKILL);
+               waitpid(pid, NULL, 0);
+               SKIP(return, "Failed to get namespace IDs from child");
+       }
+
+       TH_LOG("Parent user namespace ID: %llu", (unsigned long long)parent_ns_id);
+       TH_LOG("Child user namespace ID: %llu", (unsigned long long)child_ns_id);
+
+       /* List all user namespaces */
+       ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0);
+
+       if (ret < 0 && errno == ENOSYS) {
+               close(sv[0]);
+               kill(pid, SIGKILL);
+               waitpid(pid, NULL, 0);
+               SKIP(return, "listns() not supported");
+       }
+
+       ASSERT_GE(ret, 0);
+       TH_LOG("Found %zd active user namespaces", ret);
+
+       /* Both parent and child should be visible (active due to child process) */
+       found_parent = false;
+       found_child = false;
+       for (ssize_t i = 0; i < ret; i++) {
+               if (ns_ids[i] == parent_ns_id)
+                       found_parent = true;
+               if (ns_ids[i] == child_ns_id)
+                       found_child = true;
+       }
+
+       TH_LOG("Parent namespace %s, child namespace %s",
+              found_parent ? "found" : "NOT FOUND",
+              found_child ? "found" : "NOT FOUND");
+
+       ASSERT_TRUE(found_child);
+       /* With hierarchical propagation, parent should also be active */
+       ASSERT_TRUE(found_parent);
+
+       /* Signal child to exit */
+       if (write(sv[0], "X", 1) != 1) {
+               close(sv[0]);
+               kill(pid, SIGKILL);
+               waitpid(pid, NULL, 0);
+               ASSERT_TRUE(false);
+       }
+       close(sv[0]);
+       waitpid(pid, &status, 0);
+}
+
 TEST_HARNESS_MAIN