[PATCH v9 1/6] bpf: add new prog type for cgroup socket filtering

[Daniel Mack]

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 <dan...@zonque.org>
Acked-by: Alexei Starovoitov <a...@kernel.org>
---
 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 f09c70b..1f3e6f1 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_SKB,
 };
 
+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 00351cd..e3813d6 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2576,6 +2576,17 @@ xdp_func_proto(enum bpf_func_id func_id)
        }
 }
 
+static const struct bpf_func_proto *
+cg_skb_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))
@@ -2938,6 +2949,12 @@ static const struct bpf_verifier_ops xdp_ops = {
        .convert_ctx_access     = xdp_convert_ctx_access,
 };
 
+static const struct bpf_verifier_ops cg_skb_ops = {
+       .get_func_proto         = cg_skb_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,
@@ -2958,12 +2975,18 @@ static struct bpf_prog_type_list xdp_type __read_mostly 
= {
        .type   = BPF_PROG_TYPE_XDP,
 };
 
+static struct bpf_prog_type_list cg_skb_type __read_mostly = {
+       .ops    = &cg_skb_ops,
+       .type   = BPF_PROG_TYPE_CGROUP_SKB,
+};
+
 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_skb_type);
 
        return 0;
 }
-- 
2.7.4