linux-toradex.git/include/uapi/linux/tcp.h, branch v6.16-rc6

tcp: fastopen: pass TFO child indication through getsockopt

2025-04-25T01:21:04+00:00

tcp: fastopen: pass TFO child indication through getsockopt

Note that this uses up the last bit of a field in struct tcp_info

Signed-off-by: Jeremy Harris 
Reviewed-by: Eric Dumazet 
Reviewed-by: Neal Cardwell 
Link: https://patch.msgid.link/20250423124334.4916-3-jgh@exim.org
Signed-off-by: Jakub Kicinski

tcp: support TCP_DELACK_MAX_US for set/getsockopt use

2025-03-25T11:27:20+00:00

Support adjusting/reading delayed ack max for socket level by using
set/getsockopt().

This option aligns with TCP_BPF_DELACK_MAX usage. Considering that bpf
option was implemented before this patch, so we need to use a standalone
new option for pure tcp set/getsockopt() use.

Add WRITE_ONCE/READ_ONCE() to prevent data-race if setsockopt()
happens to write one value to icsk_delack_max while icsk_delack_max is
being read.

Signed-off-by: Jason Xing 
Reviewed-by: Eric Dumazet 
Link: https://patch.msgid.link/20250317120314.41404-3-kerneljasonxing@gmail.com
Signed-off-by: Jakub Kicinski

tcp: support TCP_RTO_MIN_US for set/getsockopt use

2025-03-25T11:27:19+00:00

Support adjusting/reading RTO MIN for socket level by using set/getsockopt().

This new option has the same effect as TCP_BPF_RTO_MIN, which means it
doesn't affect RTAX_RTO_MIN usage (by using ip route...). Considering that
bpf option was implemented before this patch, so we need to use a standalone
new option for pure tcp set/getsockopt() use.

When the socket is created, its icsk_rto_min is set to the default
value that is controlled by sysctl_tcp_rto_min_us. Then if application
calls setsockopt() with TCP_RTO_MIN_US flag to pass a valid value, then
icsk_rto_min will be overridden in jiffies unit.

This patch adds WRITE_ONCE/READ_ONCE to avoid data-race around
icsk_rto_min.

Signed-off-by: Jason Xing 
Reviewed-by: Eric Dumazet 
Link: https://patch.msgid.link/20250317120314.41404-2-kerneljasonxing@gmail.com
Signed-off-by: Jakub Kicinski

tcp: extend TCP flags to allow AE bit/ACE field

2025-03-17T13:49:46+00:00

With AccECN, there's one additional TCP flag to be used (AE)
and ACE field that overloads the definition of AE, CWR, and
ECE flags. As tcp_flags was previously only 1 byte, the
byte-order stuff needs to be added to it's handling.

Signed-off-by: Ilpo Järvinen 
Signed-off-by: Chia-Yu Chang 
Reviewed-by: Eric Dumazet 
Signed-off-by: David S. Miller

tcp: add the ability to control max RTO

2025-02-11T12:08:00+00:00

Currently, TCP stack uses a constant (120 seconds)
to limit the RTO value exponential growth.

Some applications want to set a lower value.

Add TCP_RTO_MAX_MS socket option to set a value (in ms)
between 1 and 120 seconds.

It is discouraged to change the socket rto max on a live
socket, as it might lead to unexpected disconnects.

Following patch is adding a netns sysctl to control the
default value at socket creation time.

Signed-off-by: Eric Dumazet 
Reviewed-by: Jason Xing 
Reviewed-by: Neal Cardwell 
Reviewed-by: Kuniyuki Iwashima 
Signed-off-by: Paolo Abeni

tcp: socket option to check for MPTCP fallback to TCP

2024-05-13T21:48:04+00:00

A way for an application to know if an MPTCP connection fell back to TCP
is to use getsockopt(MPTCP_INFO) and look for errors. The issue with
this technique is that the same errors -- EOPNOTSUPP (IPv4) and
ENOPROTOOPT (IPv6) -- are returned if there was a fallback, *or* if the
kernel doesn't support this socket option. The userspace then has to
look at the kernel version to understand what the errors mean.

It is not clean, and it doesn't take into account older kernels where
the socket option has been backported. A cleaner way would be to expose
this info to the TCP socket level. In case of MPTCP socket where no
fallback happened, the socket options for the TCP level will be handled
in MPTCP code, in mptcp_getsockopt_sol_tcp(). If not, that will be in
TCP code, in do_tcp_getsockopt(). So MPTCP simply has to set the value
1, while TCP has to set 0.

If the socket option is not supported, one of these two errors will be
reported:
- EOPNOTSUPP (95 - Operation not supported) for MPTCP sockets
- ENOPROTOOPT (92 - Protocol not available) for TCP sockets, e.g. on the
socket received after an 'accept()', when the client didn't request to
use MPTCP: this socket will be a TCP one, even if the listen socket
was an MPTCP one.

With this new option, the kernel can return a clear answer to both "Is
this kernel new enough to tell me the fallback status?" and "If it is
new enough, is it currently a TCP or MPTCP socket?" questions, while not
breaking the previous method.

Acked-by: Mat Martineau
Signed-off-by: Matthieu Baerts (NGI0)
Link: https://lore.kernel.org/r/20240509-upstream-net-next-20240509-mptcp-tcp_is_mptcp-v1-1-f846df999202@kernel.org
Signed-off-by: Jakub Kicinski

net/tcp: Add TCP_AO_REPAIR

2023-10-27T09:35:46+00:00

Add TCP_AO_REPAIR setsockopt(), getsockopt(). They let a user to repair
TCP-AO ISNs/SNEs. Also let the user hack around when (tp->repair) is on
and add ao_info on a socket in any supported state.
As SNEs now can be read/written at any moment, use
WRITE_ONCE()/READ_ONCE() to set/read them.

Signed-off-by: Dmitry Safonov 
Acked-by: David Ahern 
Signed-off-by: David S. Miller

net/tcp: Allow asynchronous delete for TCP-AO keys (MKTs)

2023-10-27T09:35:45+00:00

Delete becomes very, very fast - almost free, but after setsockopt()
syscall returns, the key is still alive until next RCU grace period.
Which is fine for listen sockets as userspace needs to be aware of
setsockopt(TCP_AO) and accept() race and resolve it with verification
by getsockopt() after TCP connection was accepted.

The benchmark results (on non-loaded box, worse with more RCU work pending):
> ok 33    Worst case delete    16384 keys: min=5ms max=10ms mean=6.93904ms stddev=0.263421
> ok 34        Add a new key    16384 keys: min=1ms max=4ms mean=2.17751ms stddev=0.147564
> ok 35 Remove random-search    16384 keys: min=5ms max=10ms mean=6.50243ms stddev=0.254999
> ok 36         Remove async    16384 keys: min=0ms max=0ms mean=0.0296107ms stddev=0.0172078

Co-developed-by: Francesco Ruggeri 
Signed-off-by: Francesco Ruggeri 
Co-developed-by: Salam Noureddine 
Signed-off-by: Salam Noureddine 
Signed-off-by: Dmitry Safonov 
Acked-by: David Ahern 
Signed-off-by: David S. Miller

net/tcp: Add TCP-AO getsockopt()s

2023-10-27T09:35:45+00:00

Introduce getsockopt(TCP_AO_GET_KEYS) that lets a user get TCP-AO keys
and their properties from a socket. The user can provide a filter
to match the specific key to be dumped or ::get_all = 1 may be
used to dump all keys in one syscall.

Add another getsockopt(TCP_AO_INFO) for providing per-socket/per-ao_info
stats: packet counters, Current_key/RNext_key and flags like
::ao_required and ::accept_icmps.

Co-developed-by: Francesco Ruggeri 
Signed-off-by: Francesco Ruggeri 
Co-developed-by: Salam Noureddine 
Signed-off-by: Salam Noureddine 
Signed-off-by: Dmitry Safonov 
Acked-by: David Ahern 
Signed-off-by: David S. Miller

net/tcp: Add option for TCP-AO to (not) hash header

2023-10-27T09:35:45+00:00

Provide setsockopt() key flag that makes TCP-AO exclude hashing TCP
header for peers that match the key. This is needed for interraction
with middleboxes that may change TCP options, see RFC5925 (9.2).

Co-developed-by: Francesco Ruggeri 
Signed-off-by: Francesco Ruggeri 
Co-developed-by: Salam Noureddine 
Signed-off-by: Salam Noureddine 
Signed-off-by: Dmitry Safonov 
Acked-by: David Ahern 
Signed-off-by: David S. Miller