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

-----Original Message-----
From: John Fastabend [mailto:john.fastabend@gmail.com]
Sent: Monday, October 18, 2021 9:54 PM
To: Jakub Sitnicki <jakub@cloudflare.com>; liujian (CE)
[off-list ref]
Cc: john.fastabend@gmail.com; daniel@iogearbox.net; lmb@cloudflare.com;
edumazet@google.com; davem@davemloft.net; kuba@kernel.org;
yoshfuji@linux-ipv6.org; dsahern@kernel.org; ast@kernel.org;
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kpsingh@kernel.org; netdev@vger.kernel.org; bpf@vger.kernel.org
Subject: Re: [PATCH] bpf, sockmap: Do not read sk_receive_queue in
tcp_bpf_recvmsg if strparser enabled

Jakub Sitnicki wrote:

quoted

On Fri, Oct 15, 2021 at 10:01 AM CEST, Liu Jian wrote:

quoted

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 <redacted>
---

[...]

quoted

 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)

quoted

quoted

 	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.

Liu, did you see this. I think its a bit cleaner, avoids the extra parser check in
hotpath, and should solve the issue?

https://patchwork.kernel.org/project/netdevbpf/patch/20211011191647.418
704-3-john.fastabend@gmail.com/

I think it should also address Jakub's concern.

I am sorry, I did not see the patch before.
I think it can solve my issue, please ignore my patch.
Thanks.

Thanks,
John

quoted

quoted

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

[...]