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bpf: Allow to retrieve cgroup v1 classid from v2 hooks

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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
This commit is contained in:
Daniel Borkmann 2020-03-27 16:58:53 +01:00 committed by Alexei Starovoitov
parent f318903c0b
commit 5a52ae4e32
2 changed files with 27 additions and 1 deletions
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7
include/net/cls_cgroup.h
View file

@ -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'

21
net/core/filter.c
View file

@ -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;