Skip to content
Commit b18afb6f authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by Alexei Starovoitov
Browse files

tcp: Move tcp_ns_to_ts() to tcp.h



We will support arbitrary SYN Cookie with BPF.

When BPF prog validates ACK and kfunc allocates a reqsk, we need
to call tcp_ns_to_ts() to calculate an offset of TSval for later
use:

  time
  t0 : Send SYN+ACK
       -> tsval = Initial TSval (Random Number)

  t1 : Recv ACK of 3WHS
       -> tsoff = TSecr - tcp_ns_to_ts(usec_ts_ok, tcp_clock_ns())
                = Initial TSval - t1

  t2 : Send ACK
       -> tsval = t2 + tsoff
                = Initial TSval + (t2 - t1)
                = Initial TSval + Time Delta (x)

  (x) Note that the time delta does not include the initial RTT
      from t0 to t1.

Let's move tcp_ns_to_ts() to tcp.h.

Signed-off-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20240115205514.68364-2-kuniyu@amazon.com


Signed-off-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent d177c1be
Loading
Loading
Loading
Loading
0% Loading or .
You are about to add 0 people to the discussion. Proceed with caution.
Please register or to comment