From: Daniel Borkmann <daniel@iogearbox.net>
Date: Fri, 27 Mar 2020 16:58:53 +0100
Subject: bpf: Allow to retrieve cgroup v1 classid from v2 hooks
Patch-mainline: v5.7-rc1
Git-commit: 5a52ae4e32a61ad06ef67f0b3123adbdbac4fb83
References: bsc#1177028
Today, Kubernetes is still operating on cgroups v1, however, it is
possible to retrieve the task's classid based on 'current' out of
connect(), sendmsg(), recvmsg() and bind-related hooks for orchestrators
which attach to the root cgroup v2 hook in a mixed env like in case
of Cilium, for example, in order to then correlate certain pod traffic
and use it as part of the key for BPF map lookups.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/555e1c69db7376c0947007b4951c260e1074efc3.1585323121.git.daniel@iogearbox.net
Acked-by: Gary Lin <glin@suse.com>
---
include/net/cls_cgroup.h | 7 ++++++-
net/core/filter.c | 21 +++++++++++++++++++++
2 files changed, 27 insertions(+), 1 deletion(-)
--- a/include/net/cls_cgroup.h
+++ b/include/net/cls_cgroup.h
@@ -45,9 +45,14 @@ static inline void sock_update_classid(s
sock_cgroup_set_classid(skcd, classid);
}
+static inline u32 __task_get_classid(struct task_struct *task)
+{
+ return task_cls_state(task)->classid;
+}
+
static inline u32 task_get_classid(const struct sk_buff *skb)
{
- u32 classid = task_cls_state(current)->classid;
+ u32 classid = __task_get_classid(current);
/* Due to the nature of the classifier it is required to ignore all
* packets originating from softirq context as accessing `current'
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2642,6 +2642,19 @@ static const struct bpf_func_proto bpf_m
.arg4_type = ARG_ANYTHING,
};
+#ifdef CONFIG_CGROUP_NET_CLASSID
+BPF_CALL_0(bpf_get_cgroup_classid_curr)
+{
+ return __task_get_classid(current);
+}
+
+static const struct bpf_func_proto bpf_get_cgroup_classid_curr_proto = {
+ .func = bpf_get_cgroup_classid_curr,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+};
+#endif
+
BPF_CALL_1(bpf_get_cgroup_classid, const struct sk_buff *, skb)
{
return task_get_classid(skb);
@@ -6025,6 +6038,10 @@ sock_filter_func_proto(enum bpf_func_id
return &bpf_get_netns_cookie_sock_proto;
case BPF_FUNC_perf_event_output:
return &bpf_event_output_data_proto;
+#ifdef CONFIG_CGROUP_NET_CLASSID
+ case BPF_FUNC_get_cgroup_classid:
+ return &bpf_get_cgroup_classid_curr_proto;
+#endif
default:
return bpf_base_func_proto(func_id);
}
@@ -6055,6 +6072,10 @@ sock_addr_func_proto(enum bpf_func_id fu
return &bpf_get_local_storage_proto;
case BPF_FUNC_perf_event_output:
return &bpf_event_output_data_proto;
+#ifdef CONFIG_CGROUP_NET_CLASSID
+ case BPF_FUNC_get_cgroup_classid:
+ return &bpf_get_cgroup_classid_curr_proto;
+#endif
#ifdef CONFIG_INET
case BPF_FUNC_sk_lookup_tcp:
return &bpf_sock_addr_sk_lookup_tcp_proto;