lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Wed, 20 Apr 2022 14:53:01 +0200
From:   Toke Høiland-Jørgensen <>
Cc:     Tonghao Zhang <>,
        Alexei Starovoitov <>,
        Daniel Borkmann <>,
        Andrii Nakryiko <>,
        Martin KaFai Lau <>,
        Song Liu <>, Yonghong Song <>,
        John Fastabend <>,
        KP Singh <>, Jiri Olsa <>,
        Dave Marchevsky <>,
        Kuniyuki Iwashima <>,
        Joanne Koong <>,
        Geliang Tang <>,
        "David S. Miller" <>,
        Jakub Kicinski <>,
        Eric Dumazet <>
Subject: Re: [net-next v1] bpf: add bpf_ktime_get_real_ns helper writes:

> From: Tonghao Zhang <>
> This patch introduce a new bpf_ktime_get_real_ns helper, which may
> help us to measure the skb latency in the ingress/forwarding path:
> HW/SW[1] -> ip_rcv/tcp_rcv_established -> tcp_recvmsg_locked/tcp_update_recv_tstamps
> * Insert BPF kprobe into ip_rcv/tcp_rcv_established invoking this helper.
>   Then we can inspect how long time elapsed since HW/SW.
> * If inserting BPF kprobe tcp_update_recv_tstamps invoked by tcp_recvmsg,
>   we can measure how much latency skb in tcp receive queue. The reason for
>   this can be application fetch the TCP messages too late.

Why not just use one of the existing ktime helpers and also add a BPF
probe to set the initial timestamp instead of relying on skb->tstamp?


Powered by blists - more mailing lists