bpf: introduce the bpf_get_local_storage() helper function

The bpf_get_local_storage() helper function is used
to get a pointer to the bpf local storage from a bpf program.

It takes a pointer to a storage map and flags as arguments.
Right now it accepts only cgroup storage maps, and flags
argument has to be 0. Further it can be extended to support
other types of local storage: e.g. thread local storage etc.

Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 22 insertions, 1 deletions

diff --git a/net/core/filter.c b/net/core/filter.c
index 9bb9a4488e25..9f73aae2f089 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4820,6 +4820,8 @@ sock_filter_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 	 */
 	case BPF_FUNC_get_current_uid_gid:
 		return &bpf_get_current_uid_gid_proto;
+	case BPF_FUNC_get_local_storage:
+		return &bpf_get_local_storage_proto;
 	default:
 		return bpf_base_func_proto(func_id);
 	}
@@ -4844,6 +4846,8 @@ sock_addr_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		}
 	case BPF_FUNC_get_socket_cookie:
 		return &bpf_get_socket_cookie_sock_addr_proto;
+	case BPF_FUNC_get_local_storage:
+		return &bpf_get_local_storage_proto;
 	default:
 		return bpf_base_func_proto(func_id);
 	}
@@ -4867,6 +4871,17 @@ sk_filter_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 }
 
 static const struct bpf_func_proto *
+cg_skb_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
+{
+	switch (func_id) {
+	case BPF_FUNC_get_local_storage:
+		return &bpf_get_local_storage_proto;
+	default:
+		return sk_filter_func_proto(func_id, prog);
+	}
+}
+
+static const struct bpf_func_proto *
 tc_cls_act_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 {
 	switch (func_id) {
@@ -4988,6 +5003,8 @@ sock_ops_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_sock_hash_update_proto;
 	case BPF_FUNC_get_socket_cookie:
 		return &bpf_get_socket_cookie_sock_ops_proto;
+	case BPF_FUNC_get_local_storage:
+		return &bpf_get_local_storage_proto;
 	default:
 		return bpf_base_func_proto(func_id);
 	}
@@ -5007,6 +5024,8 @@ sk_msg_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_msg_cork_bytes_proto;
 	case BPF_FUNC_msg_pull_data:
 		return &bpf_msg_pull_data_proto;
+	case BPF_FUNC_get_local_storage:
+		return &bpf_get_local_storage_proto;
 	default:
 		return bpf_base_func_proto(func_id);
 	}
@@ -5034,6 +5053,8 @@ sk_skb_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_sk_redirect_map_proto;
 	case BPF_FUNC_sk_redirect_hash:
 		return &bpf_sk_redirect_hash_proto;
+	case BPF_FUNC_get_local_storage:
+		return &bpf_get_local_storage_proto;
 	default:
 		return bpf_base_func_proto(func_id);
 	}
@@ -6838,7 +6859,7 @@ const struct bpf_prog_ops xdp_prog_ops = {
 };
 
 const struct bpf_verifier_ops cg_skb_verifier_ops = {
-	.get_func_proto		= sk_filter_func_proto,
+	.get_func_proto		= cg_skb_func_proto,
 	.is_valid_access	= sk_filter_is_valid_access,
 	.convert_ctx_access	= bpf_convert_ctx_access,
 };