bpf: Support socket lookup in CGROUP_SOCK_ADDR progs

Make bpf_sk_lookup_tcp, bpf_sk_lookup_udp and bpf_sk_release helpers
available in programs of type BPF_PROG_TYPE_CGROUP_SOCK_ADDR.

Such programs operate on sockets and have access to socket and struct
sockaddr passed by user to system calls such as sys_bind, sys_connect,
sys_sendmsg.

It's useful to be able to lookup other sockets from these programs.
E.g. sys_connect may lookup IP:port endpoint and if there is a server
socket bound to that endpoint ("server" can be defined by saddr & sport
being zero), redirect client connection to it by rewriting IP:port in
sockaddr passed to sys_connect.

Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/net/core/filter.c b/net/core/filter.c
index f4ae933edf61980d003f7fe796b4d23c1f3d1d80..f6ca38a7d4332ddcdb6d421eb2b07fff53efb564 100644 (file)
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5042,6 +5042,43 @@ static const struct bpf_func_proto bpf_xdp_sk_lookup_tcp_proto = {
        .arg4_type      = ARG_ANYTHING,
        .arg5_type      = ARG_ANYTHING,
 };
+
+BPF_CALL_5(bpf_sock_addr_sk_lookup_tcp, struct bpf_sock_addr_kern *, ctx,
+          struct bpf_sock_tuple *, tuple, u32, len, u64, netns_id, u64, flags)
+{
+       return __bpf_sk_lookup(NULL, tuple, len, sock_net(ctx->sk), 0,
+                              IPPROTO_TCP, netns_id, flags);
+}
+
+static const struct bpf_func_proto bpf_sock_addr_sk_lookup_tcp_proto = {
+       .func           = bpf_sock_addr_sk_lookup_tcp,
+       .gpl_only       = false,
+       .ret_type       = RET_PTR_TO_SOCKET_OR_NULL,
+       .arg1_type      = ARG_PTR_TO_CTX,
+       .arg2_type      = ARG_PTR_TO_MEM,
+       .arg3_type      = ARG_CONST_SIZE,
+       .arg4_type      = ARG_ANYTHING,
+       .arg5_type      = ARG_ANYTHING,
+};
+
+BPF_CALL_5(bpf_sock_addr_sk_lookup_udp, struct bpf_sock_addr_kern *, ctx,
+          struct bpf_sock_tuple *, tuple, u32, len, u64, netns_id, u64, flags)
+{
+       return __bpf_sk_lookup(NULL, tuple, len, sock_net(ctx->sk), 0,
+                              IPPROTO_UDP, netns_id, flags);
+}
+
+static const struct bpf_func_proto bpf_sock_addr_sk_lookup_udp_proto = {
+       .func           = bpf_sock_addr_sk_lookup_udp,
+       .gpl_only       = false,
+       .ret_type       = RET_PTR_TO_SOCKET_OR_NULL,
+       .arg1_type      = ARG_PTR_TO_CTX,
+       .arg2_type      = ARG_PTR_TO_MEM,
+       .arg3_type      = ARG_CONST_SIZE,
+       .arg4_type      = ARG_ANYTHING,
+       .arg5_type      = ARG_ANYTHING,
+};
+
 #endif /* CONFIG_INET */
 
 bool bpf_helper_changes_pkt_data(void *func)
@@ -5148,6 +5185,14 @@ sock_addr_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
                return &bpf_get_socket_cookie_sock_addr_proto;
        case BPF_FUNC_get_local_storage:
                return &bpf_get_local_storage_proto;
+#ifdef CONFIG_INET
+       case BPF_FUNC_sk_lookup_tcp:
+               return &bpf_sock_addr_sk_lookup_tcp_proto;
+       case BPF_FUNC_sk_lookup_udp:
+               return &bpf_sock_addr_sk_lookup_udp_proto;
+       case BPF_FUNC_sk_release:
+               return &bpf_sk_release_proto;
+#endif /* CONFIG_INET */
        default:
                return bpf_base_func_proto(func_id);
        }