Re: [PATCH v2 bpf-next 5/5] bpf: Make bpf_cgroup_read_xattr available to cgroup and struct_ops progs

[Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx>]

On Thu, Jun 19, 2025 at 3:02 PM Song Liu <song@xxxxxxxxxx> wrote:
>
> cgroup BPF programs and struct_ops BPF programs (such as sched_ext), need
> bpf_cgroup_read_xattr. Make bpf_cgroup_read_xattr available to these prog
> types.

...

> +       ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_LSM, &bpf_lsm_fs_kfunc_set);
> +       ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS, &bpf_fs_kfunc_set);
> +       ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_CGROUP_SKB, &bpf_fs_kfunc_set);
> +       ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_CGROUP_SOCK, &bpf_fs_kfunc_set);
> +       ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_CGROUP_DEVICE, &bpf_fs_kfunc_set);
> +       ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_CGROUP_SOCK_ADDR, &bpf_fs_kfunc_set);
> +       ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_CGROUP_SYSCTL, &bpf_fs_kfunc_set);
> +       return ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_CGROUP_SOCKOPT, &bpf_fs_kfunc_set);

No need to artificially restrict it like this.
bpf_cgroup_read_xattr() is generic enough and the verifier will enforce
the safety due to KF_RCU.
Just add it to common_btf_ids.