Commit f7c6cb1d authored Jul 28, 2020 by Stanislav Fomichev Committed by Daniel Borkmann Jul 31, 2020

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

parent 12e6196f

net/core/bpf_sk_storage.c

+10 −0

Original line number	Diff line number	Diff line
		@@ -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,

net/core/filter.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -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);
		}