bpf: Expose socket storage to BPF_PROG_TYPE_CGROUP_SOCK

This lets us use socket storage from the following hooks:

* BPF_CGROUP_INET_SOCK_CREATE
* BPF_CGROUP_INET_SOCK_RELEASE
* BPF_CGROUP_INET4_POST_BIND
* BPF_CGROUP_INET6_POST_BIND

Using existing 'bpf_sk_storage_get_proto' doesn't work because
second argument is ARG_PTR_TO_SOCKET. Even though
BPF_PROG_TYPE_CGROUP_SOCK hooks operate on 'struct bpf_sock',
the verifier still considers it as a PTR_TO_CTX.
That's why I'm adding another 'bpf_sk_storage_get_cg_sock_proto'
definition strictly for BPF_PROG_TYPE_CGROUP_SOCK which accepts
ARG_PTR_TO_CTX which is really 'struct sock' for this program type.

Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200729003104.1280813-1-sdf@google.com

diff --git a/net/core/bpf_sk_storage.c b/net/core/bpf_sk_storage.c
index eafcd15..d3377c9 100644 (file)
--- a/net/core/bpf_sk_storage.c
+++ b/net/core/bpf_sk_storage.c
@@ -944,6 +944,16 @@ const struct bpf_func_proto bpf_sk_storage_get_proto = {
        .arg4_type      = ARG_ANYTHING,
 };
 
+const struct bpf_func_proto bpf_sk_storage_get_cg_sock_proto = {
+       .func           = bpf_sk_storage_get,
+       .gpl_only       = false,
+       .ret_type       = RET_PTR_TO_MAP_VALUE_OR_NULL,
+       .arg1_type      = ARG_CONST_MAP_PTR,
+       .arg2_type      = ARG_PTR_TO_CTX, /* context is 'struct sock' */
+       .arg3_type      = ARG_PTR_TO_MAP_VALUE_OR_NULL,
+       .arg4_type      = ARG_ANYTHING,
+};
+
 const struct bpf_func_proto bpf_sk_storage_delete_proto = {
        .func           = bpf_sk_storage_delete,
        .gpl_only       = false,

diff --git a/net/core/filter.c b/net/core/filter.c
index 29e3455..7124f0f 100644 (file)
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -6187,6 +6187,7 @@ bool bpf_helper_changes_pkt_data(void *func)
 }
 
 const struct bpf_func_proto bpf_event_output_data_proto __weak;
+const struct bpf_func_proto bpf_sk_storage_get_cg_sock_proto __weak;
 
 static const struct bpf_func_proto *
 sock_filter_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
@@ -6219,6 +6220,8 @@ sock_filter_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
        case BPF_FUNC_get_cgroup_classid:
                return &bpf_get_cgroup_classid_curr_proto;
 #endif
+       case BPF_FUNC_sk_storage_get:
+               return &bpf_sk_storage_get_cg_sock_proto;
        default:
                return bpf_base_func_proto(func_id);
        }