[RESEND,0/2] TCP: Fast-Open observability

Message

Jeremy Harris April 16, 2025, 9:08 a.m. UTC

Whether TCP Fast Open was used for a connection is not reliably
observable by an accepting application when the SYN passed no data.

Fix this by noting during SYN receive processing that an acceptable Fast Open
option was used, and provide this to userland via getsockopt TCP_INFO.

Jeremy Harris (2):
  TCP: note received valid-cookie Fast Open option
  TCP: pass accepted-TFO indication through getsockopt

 include/linux/tcp.h      | 3 ++-
 include/uapi/linux/tcp.h | 1 +
 net/ipv4/tcp.c           | 2 ++
 net/ipv4/tcp_fastopen.c  | 1 +
 4 files changed, 6 insertions(+), 1 deletion(-)


base-commit: 24e31e4747698dc50d408f0082d7eb9b9520d2f6