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selftests/namespaces: eigth active reference count tests

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Test that bind mounts keep namespaces in the tree even when inactive

Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-30-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner
2025-10-29 13:20:43 +01:00
parent 4b971b07e4
commit 94f8711080
1 changed files with 117 additions and 0 deletions
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117
tools/testing/selftests/namespaces/ns_active_ref_test.c
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@@ -825,4 +825,121 @@ TEST(ns_parent_always_reachable)
ASSERT_TRUE(errno == ENOENT || errno == ESTALE);
}
/*
* Test that bind mounts keep namespaces in the tree even when inactive
*/
TEST(ns_bind_mount_keeps_in_tree)
{
struct file_handle *handle;
int mount_id;
int ret;
int fd;
int pipefd[2];
pid_t pid;
int status;
char buf[sizeof(*handle) + MAX_HANDLE_SZ];
char tmpfile[] = "/tmp/ns-test-XXXXXX";
int tmpfd;
/* Create temporary file for bind mount */
tmpfd = mkstemp(tmpfile);
if (tmpfd < 0) {
SKIP(return, "Cannot create temporary file");
}
close(tmpfd);
ASSERT_EQ(pipe(pipefd), 0);
pid = fork();
ASSERT_GE(pid, 0);
if (pid == 0) {
/* Child process */
close(pipefd[0]);
/* Unshare mount namespace and make mounts private to avoid propagation */
ret = unshare(CLONE_NEWNS);
if (ret < 0) {
close(pipefd[1]);
unlink(tmpfile);
exit(1);
}
ret = mount(NULL, "/", NULL, MS_PRIVATE | MS_REC, NULL);
if (ret < 0) {
close(pipefd[1]);
unlink(tmpfile);
exit(1);
}
/* Create new network namespace */
ret = unshare(CLONE_NEWNET);
if (ret < 0) {
close(pipefd[1]);
unlink(tmpfile);
exit(1);
}
/* Bind mount the namespace */
ret = mount("/proc/self/ns/net", tmpfile, NULL, MS_BIND, NULL);
if (ret < 0) {
close(pipefd[1]);
unlink(tmpfile);
exit(1);
}
/* Get file handle */
fd = open("/proc/self/ns/net", O_RDONLY);
if (fd < 0) {
umount(tmpfile);
close(pipefd[1]);
unlink(tmpfile);
exit(1);
}
handle = (struct file_handle *)buf;
handle->handle_bytes = MAX_HANDLE_SZ;
ret = name_to_handle_at(fd, "", handle, &mount_id, AT_EMPTY_PATH);
close(fd);
if (ret < 0) {
umount(tmpfile);
close(pipefd[1]);
unlink(tmpfile);
exit(1);
}
/* Send handle to parent */
write(pipefd[1], buf, sizeof(*handle) + handle->handle_bytes);
close(pipefd[1]);
exit(0);
}
/* Parent */
close(pipefd[1]);
ret = read(pipefd[0], buf, sizeof(buf));
close(pipefd[0]);
waitpid(pid, &status, 0);
ASSERT_TRUE(WIFEXITED(status));
ASSERT_EQ(WEXITSTATUS(status), 0);
ASSERT_GT(ret, 0);
handle = (struct file_handle *)buf;
/*
* Namespace should be inactive but still in tree due to bind mount.
* Reopening should fail with ENOENT (inactive) not ESTALE (not in tree).
*/
fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY);
ASSERT_LT(fd, 0);
/* Should be ENOENT (inactive) since bind mount keeps it in tree */
if (errno != ENOENT && errno != ESTALE) {
TH_LOG("Unexpected error: %d", errno);
}
/* Cleanup */
umount(tmpfile);
unlink(tmpfile);
}
TEST_HARNESS_MAIN