Commit 5a52ae4e authored by Daniel Borkmann's avatar Daniel Borkmann Committed by Alexei Starovoitov
Browse files

bpf: Allow to retrieve cgroup v1 classid from v2 hooks 



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: default avatarDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/555e1c69db7376c0947007b4951c260e1074efc3.1585323121.git.daniel@iogearbox.net
parent f318903c

include/net/cls_cgroup.h

+6 −1
Original line number Diff line number Diff line
@@ -45,9 +45,14 @@ static inline void sock_update_classid(struct sock_cgroup_data *skcd) 
	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'

net/core/filter.c

+21 −0
Original line number Diff line number Diff line
@@ -2642,6 +2642,19 @@ static const struct bpf_func_proto bpf_msg_pop_data_proto = { 
	.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);
@@ -6005,6 +6018,10 @@ sock_filter_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) 
		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);

	}
@@ -6035,6 +6052,10 @@ sock_addr_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) 
		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;

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