Jason Xing wrote:
> From: Jason Xing <kernelxing@xxxxxxxxxxx>
>
> We can set OPT_ID|OPT_ID_TCP before we initialize the last skb
> from each sendmsg. We only set the socket once like how we use
> setsockopt() with OPT_ID|OPT_ID_TCP flags.
>
> Signed-off-by: Jason Xing <kernelxing@xxxxxxxxxxx>
> ---
> net/core/skbuff.c | 16 +++++++++++++---
> net/ipv4/tcp.c | 19 +++++++++++++++----
> 2 files changed, 28 insertions(+), 7 deletions(-)
>
> @@ -491,10 +491,21 @@ static u32 bpf_tcp_tx_timestamp(struct sock *sk)
> if (!(flags & SOF_TIMESTAMPING_TX_RECORD_MASK))
> return 0;
>
> + /* We require users to set both OPT_ID and OPT_ID_TCP flags
> + * together here, or else the key might be inaccurate.
> + */
> + if (flags & SOF_TIMESTAMPING_OPT_ID &&
> + flags & SOF_TIMESTAMPING_OPT_ID_TCP &&
> + !(sk->sk_tsflags & (SOF_TIMESTAMPING_OPT_ID | SOF_TIMESTAMPING_OPT_ID_TCP))) {
> + atomic_set(&sk->sk_tskey, (tcp_sk(sk)->write_seq - copied));
> + sk->sk_tsflags |= (SOF_TIMESTAMPING_OPT_ID | SOF_TIMESTAMPING_OPT_ID_TCP);
So user and BPF admin conflict on both sk_tsflags and sktskey?
I think BPF resetting this key, or incrementing it, may break user
expectations.
