On 9/12/23 12:01 AM, Chuyi Zhou wrote:
+__bpf_kfunc int bpf_iter_css_task_new(struct bpf_iter_css_task *it,
+ struct cgroup_subsys_state *css, unsigned int flags)
+{
+ struct bpf_iter_css_task_kern *kit = (void *)it;
+
+ BUILD_BUG_ON(sizeof(struct bpf_iter_css_task_kern) != sizeof(struct bpf_iter_css_task));
+ BUILD_BUG_ON(__alignof__(struct bpf_iter_css_task_kern) !=
+ __alignof__(struct bpf_iter_css_task));
+
+ switch (flags) {
+ case CSS_TASK_ITER_PROCS | CSS_TASK_ITER_THREADED:
+ case CSS_TASK_ITER_PROCS:
+ case 0:
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ kit->css_it = kzalloc(sizeof(struct css_task_iter), GFP_KERNEL);
+ if (!kit->css_it)
+ return -ENOMEM;
+ css_task_iter_start(css, flags, kit->css_it);
+ return 0;
+}
+
+static bool check_css_task_iter_allowlist(struct bpf_verifier_env *env)
+{
+ enum bpf_prog_type prog_type = resolve_prog_type(env->prog);
+
+ switch (prog_type) {
+ case BPF_PROG_TYPE_LSM:
This will allow the non-sleepable lsm prog to call bpf_iter_css_task_new. The
above kzalloc(GFP_KERNEL) in bpf_iter_css_task_new should trigger a lockdep
error in the lsm selftest in patch 6.
+ return true;
+ case BPF_TRACE_ITER:
+ return env->prog->aux->sleepable;
+ default:
+ return false;
+ }
+}
