On Sat, Jun 20, 2020 at 10:55:06PM -0700, Yonghong Song wrote:
> Three more helpers are added to cast a sock_common pointer to
> an tcp_sock, tcp_timewait_sock or a tcp_request_sock for
> tracing programs.
>
> Signed-off-by: Yonghong Song <yhs@xxxxxx>
> ---
> include/linux/bpf.h | 3 ++
> include/uapi/linux/bpf.h | 23 ++++++++++++++-
> kernel/trace/bpf_trace.c | 6 ++++
> net/core/filter.c | 51 ++++++++++++++++++++++++++++++++++
> scripts/bpf_helpers_doc.py | 6 ++++
> tools/include/uapi/linux/bpf.h | 23 ++++++++++++++-
> 6 files changed, 110 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 0c658f78e939..b17e682454e5 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -1637,6 +1637,9 @@ extern const struct bpf_func_proto bpf_ringbuf_submit_proto;
> extern const struct bpf_func_proto bpf_ringbuf_discard_proto;
> extern const struct bpf_func_proto bpf_ringbuf_query_proto;
> extern const struct bpf_func_proto bpf_skc_to_tcp6_sock_proto;
> +extern const struct bpf_func_proto bpf_skc_to_tcp_sock_proto;
> +extern const struct bpf_func_proto bpf_skc_to_tcp_timewait_sock_proto;
> +extern const struct bpf_func_proto bpf_skc_to_tcp_request_sock_proto;
>
> const struct bpf_func_proto *bpf_tracing_func_proto(
> enum bpf_func_id func_id, const struct bpf_prog *prog);
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 394fcba27b6a..e256417d94c2 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -3258,6 +3258,24 @@ union bpf_attr {
> * Dynamically cast a *sk* pointer to a *tcp6_sock* pointer.
> * Return
> * *sk* if casting is valid, or NULL otherwise.
> + *
> + * struct tcp_sock *bpf_skc_to_tcp_sock(void *sk)
> + * Description
> + * Dynamically cast a *sk* pointer to a *tcp_sock* pointer.
> + * Return
> + * *sk* if casting is valid, or NULL otherwise.
> + *
> + * struct tcp_timewait_sock *bpf_skc_to_tcp_timewait_sock(void *sk)
> + * Description
> + * Dynamically cast a *sk* pointer to a *tcp_timewait_sock* pointer.
> + * Return
> + * *sk* if casting is valid, or NULL otherwise.
> + *
> + * struct tcp_request_sock *bpf_skc_to_tcp_request_sock(void *sk)
> + * Description
> + * Dynamically cast a *sk* pointer to a *tcp_request_sock* pointer.
> + * Return
> + * *sk* if casting is valid, or NULL otherwise.
> */
> #define __BPF_FUNC_MAPPER(FN) \
> FN(unspec), \
> @@ -3396,7 +3414,10 @@ union bpf_attr {
> FN(ringbuf_discard), \
> FN(ringbuf_query), \
> FN(csum_level), \
> - FN(skc_to_tcp6_sock),
> + FN(skc_to_tcp6_sock), \
> + FN(skc_to_tcp_sock), \
> + FN(skc_to_tcp_timewait_sock), \
> + FN(skc_to_tcp_request_sock),
>
> /* integer value in 'imm' field of BPF_CALL instruction selects which helper
> * function eBPF program intends to call
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 478c10d1ec33..de5fbe66e1ca 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -1517,6 +1517,12 @@ tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
> return &bpf_xdp_output_proto;
> case BPF_FUNC_skc_to_tcp6_sock:
> return &bpf_skc_to_tcp6_sock_proto;
> + case BPF_FUNC_skc_to_tcp_sock:
> + return &bpf_skc_to_tcp_sock_proto;
> + case BPF_FUNC_skc_to_tcp_timewait_sock:
> + return &bpf_skc_to_tcp_timewait_sock_proto;
> + case BPF_FUNC_skc_to_tcp_request_sock:
> + return &bpf_skc_to_tcp_request_sock_proto;
> #endif
> case BPF_FUNC_seq_printf:
> return prog->expected_attach_type == BPF_TRACE_ITER ?
> diff --git a/net/core/filter.c b/net/core/filter.c
> index 8ca365c5bd10..d26ce3b5e3d5 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -9271,3 +9271,54 @@ const struct bpf_func_proto bpf_skc_to_tcp6_sock_proto = {
> .check_btf_id = check_arg_btf_id,
> .ret_btf_id = &sock_cast_btf_ids[SOCK_CAST_TCP6_SOCK],
> };
> +
> +BPF_CALL_1(bpf_skc_to_tcp_sock, struct sock *, sk)
> +{
> + if (sk_fullsock(sk) && sk->sk_protocol == IPPROTO_TCP)
> + return (unsigned long)sk;
> +
> + return (unsigned long)NULL;
> +}
> +
> +const struct bpf_func_proto bpf_skc_to_tcp_sock_proto = {
> + .func = bpf_skc_to_tcp_sock,
> + .gpl_only = true,
s/true/false/
and for other bpf_func_proto below.
> + .ret_type = RET_PTR_TO_BTF_ID_OR_NULL,
> + .arg1_type = ARG_PTR_TO_BTF_ID,
> + .check_btf_id = check_arg_btf_id,
> + .ret_btf_id = &sock_cast_btf_ids[SOCK_CAST_TCP_SOCK],
> +};
> +
> +BPF_CALL_1(bpf_skc_to_tcp_timewait_sock, struct sock *, sk)
> +{
> + if (sk->sk_state == TCP_TIME_WAIT)
Not sure if checking TCP_TIME_WAIT can guarantee a tcp_timewait_sock.
dccp seems to have the same state aliased to DCCP_TIME_WAIT.
The same goes for the TCP_NEW_SYN_RECV check.
may be checking sk->sk_prot instead?
> + return (unsigned long)sk;
> +
> + return (unsigned long)NULL;
> +}
> +
> +const struct bpf_func_proto bpf_skc_to_tcp_timewait_sock_proto = {
> + .func = bpf_skc_to_tcp_timewait_sock,
> + .gpl_only = true,
> + .ret_type = RET_PTR_TO_BTF_ID_OR_NULL,
> + .arg1_type = ARG_PTR_TO_BTF_ID,
> + .check_btf_id = check_arg_btf_id,
> + .ret_btf_id = &sock_cast_btf_ids[SOCK_CAST_TCP_TW_SOCK],
> +};
> +
> +BPF_CALL_1(bpf_skc_to_tcp_request_sock, struct sock *, sk)
> +{
> + if (sk->sk_state == TCP_NEW_SYN_RECV)
> + return (unsigned long)sk;
> +
> + return (unsigned long)NULL;
> +}
> +
> +const struct bpf_func_proto bpf_skc_to_tcp_request_sock_proto = {
> + .func = bpf_skc_to_tcp_request_sock,
> + .gpl_only = true,
> + .ret_type = RET_PTR_TO_BTF_ID_OR_NULL,
> + .arg1_type = ARG_PTR_TO_BTF_ID,
> + .check_btf_id = check_arg_btf_id,
> + .ret_btf_id = &sock_cast_btf_ids[SOCK_CAST_TCP_REQ_SOCK],
> +};
