cgroup: bpf: Add bpf_skb_in_cgroup_proto
Adds a bpf helper, bpf_skb_in_cgroup, to decide if a skb->sk
belongs to a descendant of a cgroup2. It is similar to the
feature added in netfilter:
commit c38c4597e4bf ("netfilter: implement xt_cgroup cgroup2 path match")
The user is expected to populate a BPF_MAP_TYPE_CGROUP_ARRAY
which will be used by the bpf_skb_in_cgroup.
Modifications to the bpf verifier is to ensure BPF_MAP_TYPE_CGROUP_ARRAY
and bpf_skb_in_cgroup() are always used together.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Tejun Heo <tj@kernel.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/filter.c b/net/core/filter.c
index 76fee35..54071cf70 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2239,6 +2239,40 @@
}
}
+#ifdef CONFIG_SOCK_CGROUP_DATA
+static u64 bpf_skb_in_cgroup(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
+{
+ struct sk_buff *skb = (struct sk_buff *)(long)r1;
+ struct bpf_map *map = (struct bpf_map *)(long)r2;
+ struct bpf_array *array = container_of(map, struct bpf_array, map);
+ struct cgroup *cgrp;
+ struct sock *sk;
+ u32 i = (u32)r3;
+
+ sk = skb->sk;
+ if (!sk || !sk_fullsock(sk))
+ return -ENOENT;
+
+ if (unlikely(i >= array->map.max_entries))
+ return -E2BIG;
+
+ cgrp = READ_ONCE(array->ptrs[i]);
+ if (unlikely(!cgrp))
+ return -EAGAIN;
+
+ return cgroup_is_descendant(sock_cgroup_ptr(&sk->sk_cgrp_data), cgrp);
+}
+
+static const struct bpf_func_proto bpf_skb_in_cgroup_proto = {
+ .func = bpf_skb_in_cgroup,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+ .arg2_type = ARG_CONST_MAP_PTR,
+ .arg3_type = ARG_ANYTHING,
+};
+#endif
+
static const struct bpf_func_proto *
sk_filter_func_proto(enum bpf_func_id func_id)
{
@@ -2307,6 +2341,10 @@
return bpf_get_event_output_proto();
case BPF_FUNC_get_smp_processor_id:
return &bpf_get_smp_processor_id_proto;
+#ifdef CONFIG_SOCK_CGROUP_DATA
+ case BPF_FUNC_skb_in_cgroup:
+ return &bpf_skb_in_cgroup_proto;
+#endif
default:
return sk_filter_func_proto(func_id);
}