On Fri, Jan 10, 2020 at 11:50:25AM +0100, Jakub Sitnicki wrote:
> SOCKMAP now supports storing references to listening sockets. Nothing keeps
> us from using it as an array of sockets to select from in SK_REUSEPORT
> programs.
>
> Whitelist the map type with the BPF helper for selecting socket.
>
> The restriction that the socket has to be a member of a reuseport group
> still applies. Socket from a SOCKMAP that does not have sk_reuseport_cb set
> is not a valid target and we signal it with -EINVAL.
>
> Signed-off-by: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx>
> ---
> kernel/bpf/verifier.c | 6 ++++--
> net/core/filter.c | 15 ++++++++++-----
> 2 files changed, 14 insertions(+), 7 deletions(-)
>
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index f5af759a8a5f..0ee5f1594b5c 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -3697,7 +3697,8 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
> if (func_id != BPF_FUNC_sk_redirect_map &&
> func_id != BPF_FUNC_sock_map_update &&
> func_id != BPF_FUNC_map_delete_elem &&
> - func_id != BPF_FUNC_msg_redirect_map)
> + func_id != BPF_FUNC_msg_redirect_map &&
> + func_id != BPF_FUNC_sk_select_reuseport)
> goto error;
> break;
> case BPF_MAP_TYPE_SOCKHASH:
> @@ -3778,7 +3779,8 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
> goto error;
> break;
> case BPF_FUNC_sk_select_reuseport:
> - if (map->map_type != BPF_MAP_TYPE_REUSEPORT_SOCKARRAY)
> + if (map->map_type != BPF_MAP_TYPE_REUSEPORT_SOCKARRAY &&
> + map->map_type != BPF_MAP_TYPE_SOCKMAP)
> goto error;
> break;
> case BPF_FUNC_map_peek_elem:
> diff --git a/net/core/filter.c b/net/core/filter.c
> index a702761ef369..c79c62a54167 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -8677,6 +8677,7 @@ struct sock *bpf_run_sk_reuseport(struct sock_reuseport *reuse, struct sock *sk,
> BPF_CALL_4(sk_select_reuseport, struct sk_reuseport_kern *, reuse_kern,
> struct bpf_map *, map, void *, key, u32, flags)
> {
> + bool is_sockarray = map->map_type == BPF_MAP_TYPE_REUSEPORT_SOCKARRAY;
A nit.
Since map_type is tested, reuseport_array_lookup_elem() or sock_map_lookup()
can directly be called also. mostly for consideration. will not insist.
> struct sock_reuseport *reuse;
> struct sock *selected_sk;
>
