Subject: [PATCH v6 1/6] bpf: add new prog type for cgroup socket filtering

From: Daniel Mack <[email-masked]>
Date: Mon, 19 Sep 2016 18:43:56 +0200

This program type is similar to BPF_PROG_TYPE_SOCKET_FILTER, except that
it does not allow BPF_LD_[ABS|IND] instructions and hooks up the
bpf_skb_load_bytes() helper.

Programs of this type will be attached to cgroups for network filtering
and accounting.

Signed-off-by: Daniel Mack <[email-masked]>
---
 include/uapi/linux/bpf.h |  9 +++++++++
 net/core/filter.c        | 23 +++++++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index f896dfa..55f815e 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -96,8 +96,17 @@ enum bpf_prog_type {
 	BPF_PROG_TYPE_TRACEPOINT,
 	BPF_PROG_TYPE_XDP,
 	BPF_PROG_TYPE_PERF_EVENT,
+	BPF_PROG_TYPE_CGROUP_SOCKET,
 };
 
+enum bpf_attach_type {
+	BPF_CGROUP_INET_INGRESS,
+	BPF_CGROUP_INET_EGRESS,
+	__MAX_BPF_ATTACH_TYPE
+};
+
+#define MAX_BPF_ATTACH_TYPE __MAX_BPF_ATTACH_TYPE
+
 #define BPF_PSEUDO_MAP_FD	1
 
 /* flags for BPF_MAP_UPDATE_ELEM command */
diff --git a/net/core/filter.c b/net/core/filter.c
index 298b146..e46c98e 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2496,6 +2496,17 @@ xdp_func_proto(enum bpf_func_id func_id)
 	}
 }
 
+static const struct bpf_func_proto *
+cg_sk_func_proto(enum bpf_func_id func_id)
+{
+	switch (func_id) {
+	case BPF_FUNC_skb_load_bytes:
+		return &bpf_skb_load_bytes_proto;
+	default:
+		return sk_filter_func_proto(func_id);
+	}
+}
+
 static bool __is_valid_access(int off, int size, enum bpf_access_type type)
 {
 	if (off < 0 || off >= sizeof(struct __sk_buff))
@@ -2818,6 +2829,12 @@ static const struct bpf_verifier_ops xdp_ops = {
 	.convert_ctx_access	= xdp_convert_ctx_access,
 };
 
+static const struct bpf_verifier_ops cg_sk_ops = {
+	.get_func_proto		= cg_sk_func_proto,
+	.is_valid_access	= sk_filter_is_valid_access,
+	.convert_ctx_access	= sk_filter_convert_ctx_access,
+};
+
 static struct bpf_prog_type_list sk_filter_type __read_mostly = {
 	.ops	= &sk_filter_ops,
 	.type	= BPF_PROG_TYPE_SOCKET_FILTER,
@@ -2838,12 +2855,18 @@ static struct bpf_prog_type_list xdp_type __read_mostly = {
 	.type	= BPF_PROG_TYPE_XDP,
 };
 
+static struct bpf_prog_type_list cg_sk_type __read_mostly = {
+	.ops	= &cg_sk_ops,
+	.type	= BPF_PROG_TYPE_CGROUP_SOCKET,
+};
+
 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);
 	bpf_register_prog_type(&xdp_type);
+	bpf_register_prog_type(&cg_sk_type);
 
 	return 0;
 }
-- 
2.5.5