On 6/22/20 5:36 PM, Yonghong Song wrote:
> The helper is used in tracing programs to cast a socket
> pointer to a udp6_sock pointer.
> The return value could be NULL if the casting is illegal.
>
> Acked-by: Martin KaFai Lau <kafai@xxxxxx>
> Signed-off-by: Yonghong Song <yhs@xxxxxx>
> ---
> include/linux/bpf.h | 1 +
> include/uapi/linux/bpf.h | 9 ++++++++-
> kernel/trace/bpf_trace.c | 2 ++
> net/core/filter.c | 22 ++++++++++++++++++++++
> scripts/bpf_helpers_doc.py | 2 ++
> tools/include/uapi/linux/bpf.h | 9 ++++++++-
> 6 files changed, 43 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index cc3f89827b89..3f5c6bb5e3a7 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -1649,6 +1649,7 @@ 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;
> +extern const struct bpf_func_proto bpf_skc_to_udp6_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 e256417d94c2..3f4b12c5c563 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -3276,6 +3276,12 @@ union bpf_attr {
> * Dynamically cast a *sk* pointer to a *tcp_request_sock* pointer.
> * Return
> * *sk* if casting is valid, or NULL otherwise.
> + *
> + * struct udp6_sock *bpf_skc_to_udp6_sock(void *sk)
> + * Description
> + * Dynamically cast a *sk* pointer to a *udp6_sock* pointer.
> + * Return
> + * *sk* if casting is valid, or NULL otherwise.
> */
> #define __BPF_FUNC_MAPPER(FN) \
> FN(unspec), \
> @@ -3417,7 +3423,8 @@ union bpf_attr {
> FN(skc_to_tcp6_sock), \
> FN(skc_to_tcp_sock), \
> FN(skc_to_tcp_timewait_sock), \
> - FN(skc_to_tcp_request_sock),
> + FN(skc_to_tcp_request_sock), \
> + FN(skc_to_udp6_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 de5fbe66e1ca..d10ab16c4a2f 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -1523,6 +1523,8 @@ tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
> return &bpf_skc_to_tcp_timewait_sock_proto;
> case BPF_FUNC_skc_to_tcp_request_sock:
> return &bpf_skc_to_tcp_request_sock_proto;
> + case BPF_FUNC_skc_to_udp6_sock:
> + return &bpf_skc_to_udp6_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 140fc0fdf3e1..9a98f3616273 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -9325,3 +9325,25 @@ const struct bpf_func_proto bpf_skc_to_tcp_request_sock_proto = {
> .check_btf_id = check_arg_btf_id,
> .ret_btf_id = &btf_sock_ids[BTF_SOCK_TYPE_TCP_REQ],
> };
> +
> +BPF_CALL_1(bpf_skc_to_udp6_sock, struct sock *, sk)
> +{
> + /* udp6_sock type is not generated in dwarf and hence btf,
> + * trigger an explicit type generation here.
> + */
> + BTF_TYPE_EMIT(struct udp6_sock);
> + if (sk_fullsock(sk) && sk->sk_protocol == IPPROTO_UDP &&
Why is the sk_fullsock(sk) needed ?
> + sk->sk_family == AF_INET6)
> + return (unsigned long)sk;
> +
> + return (unsigned long)NULL;
> +}
> +
> +const struct bpf_func_proto bpf_skc_to_udp6_sock_proto = {
> + .func = bpf_skc_to_udp6_sock,
> + .gpl_only = false,
> + .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 = &btf_sock_ids[BTF_SOCK_TYPE_UDP6],
> +};
> diff --git a/scripts/bpf_helpers_doc.py b/scripts/bpf_helpers_doc.py
> index d886657c6aaa..6bab40ff442e 100755
> --- a/scripts/bpf_helpers_doc.py
> +++ b/scripts/bpf_helpers_doc.py
> @@ -425,6 +425,7 @@ class PrinterHelpers(Printer):
> 'struct tcp_sock',
> 'struct tcp_timewait_sock',
> 'struct tcp_request_sock',
> + 'struct udp6_sock',
>
> 'struct __sk_buff',
> 'struct sk_msg_md',
> @@ -466,6 +467,7 @@ class PrinterHelpers(Printer):
> 'struct tcp_sock',
> 'struct tcp_timewait_sock',
> 'struct tcp_request_sock',
> + 'struct udp6_sock',
> }
> mapped_types = {
> 'u8': '__u8',
> diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> index e256417d94c2..3f4b12c5c563 100644
> --- a/tools/include/uapi/linux/bpf.h
> +++ b/tools/include/uapi/linux/bpf.h
> @@ -3276,6 +3276,12 @@ union bpf_attr {
> * Dynamically cast a *sk* pointer to a *tcp_request_sock* pointer.
> * Return
> * *sk* if casting is valid, or NULL otherwise.
> + *
> + * struct udp6_sock *bpf_skc_to_udp6_sock(void *sk)
> + * Description
> + * Dynamically cast a *sk* pointer to a *udp6_sock* pointer.
> + * Return
> + * *sk* if casting is valid, or NULL otherwise.
> */
> #define __BPF_FUNC_MAPPER(FN) \
> FN(unspec), \
> @@ -3417,7 +3423,8 @@ union bpf_attr {
> FN(skc_to_tcp6_sock), \
> FN(skc_to_tcp_sock), \
> FN(skc_to_tcp_timewait_sock), \
> - FN(skc_to_tcp_request_sock),
> + FN(skc_to_tcp_request_sock), \
> + FN(skc_to_udp6_sock),
>
> /* integer value in 'imm' field of BPF_CALL instruction selects which helper
> * function eBPF program intends to call
>
