On Tue, Mar 19, 2019 at 10:20:58AM +0000, Lorenz Bauer wrote:
> Allow looking up a sock_common. This gives eBPF programs
> access to timewait and request sockets.
>
> Signed-off-by: Lorenz Bauer <lmb@xxxxxxxxxxxxxx>
> ---
> include/uapi/linux/bpf.h | 20 ++++++-
> kernel/bpf/verifier.c | 3 +-
> net/core/filter.c | 113 +++++++++++++++++++++++++++++++++++----
> 3 files changed, 124 insertions(+), 12 deletions(-)
>
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 983b25cb608d..8e4f8276942a 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -2374,6 +2374,23 @@ union bpf_attr {
> * Return
> * A **struct bpf_sock** pointer on success, or NULL in
> * case of failure.
> + *
> + * struct bpf_sock *bpf_skc_lookup_tcp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u64 netns, u64 flags)
> + * Description
> + * Look for TCP socket matching *tuple*, optionally in a child
> + * network namespace *netns*. The return value must be checked,
> + * and if non-**NULL**, released via **bpf_sk_release**\ ().
> + *
> + * This function is identical to bpf_sk_lookup_tcp, except that it
> + * also returns timewait or request sockets. Use bpf_sk_fullsock
> + * or bpf_tcp_socket to access the full structure.
> + *
> + * This helper is available only if the kernel was compiled with
> + * **CONFIG_NET** configuration option.
> + * Return
> + * Pointer to **struct bpf_sock**, or **NULL** in case of failure.
> + * For sockets with reuseport option, the **struct bpf_sock**
> + * result is from **reuse->socks**\ [] using the hash of the tuple.
> */
> #define __BPF_FUNC_MAPPER(FN) \
> FN(unspec), \
> @@ -2474,7 +2491,8 @@ union bpf_attr {
> FN(sk_fullsock), \
> FN(tcp_sock), \
> FN(skb_ecn_set_ce), \
> - FN(get_listener_sock),
> + FN(get_listener_sock), \
> + FN(skc_lookup_tcp),
>
> /* integer value in 'imm' field of BPF_CALL instruction selects which helper
> * function eBPF program intends to call
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index f60d9df4e00a..94420942af32 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -369,7 +369,8 @@ static bool is_release_function(enum bpf_func_id func_id)
> static bool is_acquire_function(enum bpf_func_id func_id)
> {
> return func_id == BPF_FUNC_sk_lookup_tcp ||
> - func_id == BPF_FUNC_sk_lookup_udp;
> + func_id == BPF_FUNC_sk_lookup_udp ||
> + func_id == BPF_FUNC_skc_lookup_tcp;
> }
>
> static bool is_ptr_cast_function(enum bpf_func_id func_id)
> diff --git a/net/core/filter.c b/net/core/filter.c
> index f879791ea53f..f5210773cfd8 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -5156,15 +5156,15 @@ static struct sock *sk_lookup(struct net *net, struct bpf_sock_tuple *tuple,
> return sk;
> }
>
> -/* bpf_sk_lookup performs the core lookup for different types of sockets,
> +/* bpf_skc_lookup performs the core lookup for different types of sockets,
> * taking a reference on the socket if it doesn't have the flag SOCK_RCU_FREE.
> * Returns the socket as an 'unsigned long' to simplify the casting in the
> * callers to satisfy BPF_CALL declarations.
> */
> static unsigned long
> -__bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len,
> - struct net *caller_net, u32 ifindex, u8 proto, u64 netns_id,
> - u64 flags)
> +__bpf_skc_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len,
> + struct net *caller_net, u32 ifindex, u8 proto, u64 netns_id,
> + u64 flags)
> {
> struct sock *sk = NULL;
> u8 family = AF_UNSPEC;
> @@ -5192,15 +5192,28 @@ __bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len,
> put_net(net);
> }
>
> - if (sk)
> - sk = sk_to_full_sk(sk);
> out:
> return (unsigned long) sk;
> }
>
> static unsigned long
> -bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len,
> - u8 proto, u64 netns_id, u64 flags)
> +__bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len,
> + struct net *caller_net, u32 ifindex, u8 proto, u64 netns_id,
> + u64 flags)
> +{
> + struct sock *sk;
> +
> + sk = (struct sock *)__bpf_skc_lookup(skb, tuple, len, caller_net,
> + ifindex, proto, netns_id, flags);
This back and forth casting of pointer and long here and in bpf_sk_lookup is not pretty.
Before this patch there was one ulong cast, but now we probably need
to refactor this a bit.
Like changing __bpf_skc_lookup to return 'struct sock *' and do final (ulong)
cast only in bpf_[xdp_]sk[c]_lookup_[tcp|udp] that return it to bpf side?
