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);
