Subject: Re: [PATCH] bpf, sockmap: Do not read sk_receive_queue in tcp_bpf_recvmsg if strparser enabled

From: Jakub Sitnicki <[email-masked]>
Date: Mon, 18 Oct 2021 10:54:41 +0200

On Fri, Oct 15, 2021 at 10:01 AM CEST, Liu Jian wrote:
> If the strparser function of sk is turned on, all received data needs to
> be processed by strparser first.
>
> Fixes: 604326b41a6fb ("bpf, sockmap: convert to generic sk_msg interface")
> Signed-off-by: Liu Jian <[email-masked]>
> ---

[...]

>  net/core/skmsg.c      | 5 +++++
>  net/ipv4/tcp_bpf.c    | 9 ++++++---
>  3 files changed, 17 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h
> index 94e2a1f6e58d..25e92dff04aa 100644
> --- a/include/linux/skmsg.h
> +++ b/include/linux/skmsg.h
> @@ -390,6 +390,7 @@ void sk_psock_stop(struct sk_psock *psock, bool wait);
>  int sk_psock_init_strp(struct sock *sk, struct sk_psock *psock);
>  void sk_psock_start_strp(struct sock *sk, struct sk_psock *psock);
>  void sk_psock_stop_strp(struct sock *sk, struct sk_psock *psock);
> +bool sk_psock_strparser_started(struct sock *sk);
>  #else
>  static inline int sk_psock_init_strp(struct sock *sk, struct sk_psock *psock)
>  {
> @@ -403,6 +404,11 @@ static inline void sk_psock_start_strp(struct sock *sk, struct sk_psock *psock)
>  static inline void sk_psock_stop_strp(struct sock *sk, struct sk_psock *psock)
>  {
>  }
> +
> +static inline bool sk_psock_strparser_started(struct sock *sk)
> +{
> +	return false;
> +}
>  #endif
>  
>  void sk_psock_start_verdict(struct sock *sk, struct sk_psock *psock);
> diff --git a/net/core/skmsg.c b/net/core/skmsg.c
> index e85b7f8491b9..dd64ef854f3e 100644
> --- a/net/core/skmsg.c
> +++ b/net/core/skmsg.c
> @@ -1105,6 +1105,11 @@ void sk_psock_start_strp(struct sock *sk, struct sk_psock *psock)
>  	sk->sk_write_space = sk_psock_write_space;
>  }
>  
> +bool sk_psock_strparser_started(struct sock *sk)
> +{
> +	return sk->sk_data_ready == sk_psock_strp_data_ready;

What if kTLS is configured on the socket? I think this check won't work then.

> +}
> +
>  void sk_psock_stop_strp(struct sock *sk, struct sk_psock *psock)
>  {
>  	if (!psock->saved_data_ready)

[...]