On Tue, Jul 22, 2025 at 05:37 PM -07, Martin KaFai Lau wrote:
> On 7/21/25 3:52 AM, Jakub Sitnicki wrote:
>> @@ -21788,12 +21798,17 @@ static void specialize_kfunc(struct bpf_verifier_env *env,
>> if (offset)
>> return;
>> - if (func_id == special_kfunc_list[KF_bpf_dynptr_from_skb]) {
>> + if (func_id == special_kfunc_list[KF_bpf_dynptr_from_skb] ||
>> + func_id == special_kfunc_list[KF_bpf_dynptr_from_skb_meta]) {
>
> I don't think this check is needed. The skb_meta is writable to tc.
>
>> seen_direct_write = env->seen_direct_write;
>> is_rdonly = !may_access_direct_pkt_data(env, NULL, BPF_WRITE);
>
> is_rdonly is always false here.
>
>> - if (is_rdonly)
>> - *addr = (unsigned long)bpf_dynptr_from_skb_rdonly;
>> + if (is_rdonly) {
>> + if (func_id == special_kfunc_list[KF_bpf_dynptr_from_skb])
>> + *addr = (unsigned long)bpf_dynptr_from_skb_rdonly;
>> + else if (func_id == special_kfunc_list[KF_bpf_dynptr_from_skb_meta])
>> + *addr = (unsigned long)bpf_dynptr_from_skb_meta_rdonly;
>> + }
>
> [ ... ]
>
>> +int bpf_dynptr_from_skb_meta_rdonly(struct __sk_buff *skb, u64 flags,
>
> so I suspect this is never used and not needed now. Please check.
> It can be revisited in the future when other hooks are supported. It will be a
> useful comment in the commit message.
You're right. This is dead code ATM. I missed that. Will remove.
[...]
