On Thu, Apr 20, 2023 at 12:27 AM Feng zhou <zhoufeng.zf@xxxxxxxxxxxxx> wrote:
>
> From: Feng Zhou <zhoufeng.zf@xxxxxxxxxxxxx>
>
> This adds a bpf helper that's similar to the
> bpf_current_task_under_cgroup. The difference is that it is a
> designated task.
>
> When hook sched related functions, sometimes it is necessary to
> specify a task instead of the current task.
>
> Signed-off-by: Feng Zhou <zhoufeng.zf@xxxxxxxxxxxxx>
> ---
> include/uapi/linux/bpf.h | 13 +++++++++++++
> kernel/bpf/verifier.c | 4 +++-
> kernel/trace/bpf_trace.c | 31 +++++++++++++++++++++++++++++++
> tools/include/uapi/linux/bpf.h | 13 +++++++++++++
> 4 files changed, 60 insertions(+), 1 deletion(-)
>
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 4b20a7269bee..3d31ddb39e10 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -5550,6 +5550,18 @@ union bpf_attr {
> * 0 on success.
> *
> * **-ENOENT** if the bpf_local_storage cannot be found.
> + *
> + * long bpf_task_under_cgroup(struct bpf_map *map, struct task_struct *task, u32 index)
> + * Description
> + * Check whether the probe is being run is the context of a given
> + * subset of the cgroup2 hierarchy. The cgroup2 to test is held by
> + * *map* of type **BPF_MAP_TYPE_CGROUP_ARRAY**, at *index*.
> + * Return
> + * The return value depends on the result of the test, and can be:
> + *
> + * * 1, if assigned task belongs to the cgroup2.
> + * * 0, if assigned task does not belong to the cgroup2.
> + * * A negative error code, if an error occurred.
> */
> #define ___BPF_FUNC_MAPPER(FN, ctx...) \
> FN(unspec, 0, ##ctx) \
> @@ -5764,6 +5776,7 @@ union bpf_attr {
> FN(user_ringbuf_drain, 209, ##ctx) \
> FN(cgrp_storage_get, 210, ##ctx) \
> FN(cgrp_storage_delete, 211, ##ctx) \
> + FN(task_under_cgroup, 212, ##ctx) \
> /* */
>
> /* backwards-compatibility macros for users of __BPF_FUNC_MAPPER that don't
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index 1e05355facdc..1e2c3c3e8d5f 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -7771,7 +7771,8 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
> break;
> case BPF_MAP_TYPE_CGROUP_ARRAY:
> if (func_id != BPF_FUNC_skb_under_cgroup &&
> - func_id != BPF_FUNC_current_task_under_cgroup)
> + func_id != BPF_FUNC_current_task_under_cgroup &&
> + func_id != BPF_FUNC_task_under_cgroup)
> goto error;
> break;
> case BPF_MAP_TYPE_CGROUP_STORAGE:
> @@ -7902,6 +7903,7 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
> goto error;
> break;
> case BPF_FUNC_current_task_under_cgroup:
> + case BPF_FUNC_task_under_cgroup:
> case BPF_FUNC_skb_under_cgroup:
> if (map->map_type != BPF_MAP_TYPE_CGROUP_ARRAY)
> goto error;
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index bcf91bc7bf71..b02a04768824 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -814,6 +814,35 @@ static const struct bpf_func_proto bpf_current_task_under_cgroup_proto = {
> .arg2_type = ARG_ANYTHING,
> };
>
> +BPF_CALL_3(bpf_task_under_cgroup, struct bpf_map *, map, struct task_struct *,
> + task, u32, idx)
> +{
> + struct bpf_array *array = container_of(map, struct bpf_array, map);
> + struct cgroup *cgrp;
> +
> + if (unlikely(!task))
> + return -ENOENT;
> +
> + if (unlikely(idx >= array->map.max_entries))
> + return -E2BIG;
> +
> + cgrp = READ_ONCE(array->ptrs[idx]);
> + if (unlikely(!cgrp))
> + return -EAGAIN;
> +
> + return task_under_cgroup_hierarchy(task, cgrp);
We don't add helpers anymore.
Please wrap task_under_cgroup_hierarchy() as a kfunc
that takes two TRUSTED pointers task and cgroup.
