ebpf: add sched_act_type and map it to sk_filter's verifier ops

In order to prepare eBPF support for tc action, we need to add sched_act_type, so that the eBPF verifier is aware of what helper function act_bpf may use, that it can load skb data and read out currently available skb fields. This is bascially analogous to 96be4325f443 ("ebpf: add sched_cls_type and map it to sk_filter's verifier ops"). BPF_PROG_TYPE_SCHED_CLS and BPF_PROG_TYPE_SCHED_ACT need to be separate since both will have a different set of functionality in future (classifier vs action), thus we won't run into ABI troubles when the point in time comes to diverge functionality from the classifier. The future plan for act_bpf would be that it will be able to write into skb->data and alter selected fields mirrored in struct __sk_buff. For an initial support, it's sufficient to map it to sk_filter_ops.

Daniel Borkmann committed 11 years ago

Commit 94caee81 parent 0fa74a43 files · +8 −0Browse files

Unified · Split

3 files

include/uapi/linux/bpf.h +1 −0
kernel/bpf/verifier.c +1 −0
net/core/filter.c +6 −0

include/uapi/linux/bpf.h+1−0

@@ -119,6 +119,7 @@ enum bpf_prog_type { · 118 unmodified lines
119	BPF_PROG_TYPE_UNSPEC,	119	BPF_PROG_TYPE_UNSPEC,
120	BPF_PROG_TYPE_SOCKET_FILTER,	120	BPF_PROG_TYPE_SOCKET_FILTER,
121	BPF_PROG_TYPE_SCHED_CLS,	121	BPF_PROG_TYPE_SCHED_CLS,
		122	BPF_PROG_TYPE_SCHED_ACT,
122	};	123	};
123		124
124	#define BPF_PSEUDO_MAP_FD 1	125	#define BPF_PSEUDO_MAP_FD 1

kernel/bpf/verifier.c+1−0

@@ -1180,6 +1180,7 @@ static bool may_access_skb(enum bpf_prog_type type) · 1179 unmodified lines
1180	switch (type) {	1180	switch (type) {
1181	case BPF_PROG_TYPE_SOCKET_FILTER:	1181	case BPF_PROG_TYPE_SOCKET_FILTER:
1182	case BPF_PROG_TYPE_SCHED_CLS:	1182	case BPF_PROG_TYPE_SCHED_CLS:
		1183	case BPF_PROG_TYPE_SCHED_ACT:
1183	return true;	1184	return true;
1184	default:	1185	default:
1185	return false;	1186	return false;

net/core/filter.c+6−0

 	.type = BPF_PROG_TYPE_SCHED_CLS,
 };
+static struct bpf_prog_type_list sched_act_type __read_mostly = {
+	.ops = &sk_filter_ops,
+	.type = BPF_PROG_TYPE_SCHED_ACT,
+};
 static int __init register_sk_filter_ops(void)
 {
 	bpf_register_prog_type(&sk_filter_type);
 	bpf_register_prog_type(&sched_cls_type);
+	bpf_register_prog_type(&sched_act_type);
 	return 0;
 }

ebpf: add sched_act_type and map it to sk_filter's verifier ops

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