linux-toradex.git/net/ipv4/sysctl_net_ipv4.c, branch v5.10-rc2

tcp: reflect tos value received in SYN to the socket

2020-09-10T20:15:40+00:00

This commit adds a new TCP feature to reflect the tos value received in
SYN, and send it out on the SYN-ACK, and eventually set the tos value of
the established socket with this reflected tos value. This provides a
way to set the traffic class/QoS level for all traffic in the same
connection to be the same as the incoming SYN request. It could be
useful in data centers to provide equivalent QoS according to the
incoming request.
This feature is guarded by /proc/sys/net/ipv4/tcp_reflect_tos, and is by
default turned off.

Signed-off-by: Wei Wang 
Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

tcp: correct read of TFO keys on big endian systems

2020-08-10T19:12:35+00:00

When TFO keys are read back on big endian systems either via the global
sysctl interface or via getsockopt() using TCP_FASTOPEN_KEY, the values
don't match what was written.

For example, on s390x:

# echo "1-2-3-4" > /proc/sys/net/ipv4/tcp_fastopen_key
# cat /proc/sys/net/ipv4/tcp_fastopen_key
02000000-01000000-04000000-03000000

Instead of:

# cat /proc/sys/net/ipv4/tcp_fastopen_key
00000001-00000002-00000003-00000004

Fix this by converting to the correct endianness on read. This was
reported by Colin Ian King when running the 'tcp_fastopen_backup_key' net
selftest on s390x, which depends on the read value matching what was
written. I've confirmed that the test now passes on big and little endian
systems.

Signed-off-by: Jason Baron 
Fixes: 438ac88009bc ("net: fastopen: robustness and endianness fixes for SipHash")
Cc: Ard Biesheuvel 
Cc: Eric Dumazet 
Reported-and-tested-by: Colin Ian King 
Signed-off-by: David S. Miller

Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

2020-05-02T00:02:27+00:00

Alexei Starovoitov says:

====================
pull-request: bpf-next 2020-05-01 (v2)

The following pull-request contains BPF updates for your *net-next* tree.

We've added 61 non-merge commits during the last 6 day(s) which contain
a total of 153 files changed, 6739 insertions(+), 3367 deletions(-).

The main changes are:

1) pulled work.sysctl from vfs tree with sysctl bpf changes.

2) bpf_link observability, from Andrii.

3) BTF-defined map in map, from Andrii.

4) asan fixes for selftests, from Andrii.

5) Allow bpf_map_lookup_elem for SOCKMAP and SOCKHASH, from Jakub.

6) production cloudflare classifier as a selftes, from Lorenz.

7) bpf_ktime_get_*_ns() helper improvements, from Maciej.

8) unprivileged bpftool feature probe, from Quentin.

9) BPF_ENABLE_STATS command, from Song.

10) enable bpf_[gs]etsockopt() helpers for sock_ops progs, from Stanislav.

11) enable a bunch of common helpers for cg-device, sysctl, sockopt progs,
 from Stanislav.
====================

Signed-off-by: David S. Miller

tcp: add hrtimer slack to sack compression

2020-04-30T20:24:01+00:00

Add a sysctl to control hrtimer slack, default of 100 usec.

This gives the opportunity to reduce system overhead,
and help very short RTT flows.

Signed-off-by: Eric Dumazet 
Acked-by: Soheil Hassas Yeganeh 
Acked-by: Neal Cardwell 
Signed-off-by: David S. Miller

net: ipv4: add sysctl for nexthop api compatibility mode

2020-04-28T19:50:37+00:00

Current route nexthop API maintains user space compatibility
with old route API by default. Dumps and netlink notifications
support both new and old API format. In systems which have
moved to the new API, this compatibility mode cancels some
of the performance benefits provided by the new nexthop API.

This patch adds new sysctl nexthop_compat_mode which is on
by default but provides the ability to turn off compatibility
mode allowing systems to run entirely with the new routing
API. Old route API behaviour and support is not modified by this
sysctl.

Uses a single sysctl to cover both ipv4 and ipv6 following
other sysctls. Covers dumps and delete notifications as
suggested by David Ahern.

Signed-off-by: Roopa Prabhu 
Reviewed-by: David Ahern 
Signed-off-by: David S. Miller

sysctl: pass kernel pointers to ->proc_handler

2020-04-27T06:07:40+00:00

Instead of having all the sysctl handlers deal with user pointers, which
is rather hairy in terms of the BPF interaction, copy the input to and
from  userspace in common code.  This also means that the strings are
always NUL-terminated by the common code, making the API a little bit
safer.

As most handler just pass through the data to one of the common handlers
a lot of the changes are mechnical.

Signed-off-by: Christoph Hellwig 
Acked-by: Andrey Ignatov 
Signed-off-by: Al Viro

tcp: bind(0) remove the SO_REUSEADDR restriction when ephemeral ports are exhausted.

2020-03-12T19:08:09+00:00

Commit aacd9289af8b82f5fb01bcdd53d0e3406d1333c7 ("tcp: bind() use stronger
condition for bind_conflict") introduced a restriction to forbid to bind
SO_REUSEADDR enabled sockets to the same (addr, port) tuple in order to
assign ports dispersedly so that we can connect to the same remote host.

The change results in accelerating port depletion so that we fail to bind
sockets to the same local port even if we want to connect to the different
remote hosts.

You can reproduce this issue by following instructions below.

  1. # sysctl -w net.ipv4.ip_local_port_range="32768 32768"
  2. set SO_REUSEADDR to two sockets.
  3. bind two sockets to (localhost, 0) and the latter fails.

Therefore, when ephemeral ports are exhausted, bind(0) should fallback to
the legacy behaviour to enable the SO_REUSEADDR option and make it possible
to connect to different remote (addr, port) tuples.

This patch allows us to bind SO_REUSEADDR enabled sockets to the same
(addr, port) only when net.ipv4.ip_autobind_reuse is set 1 and all
ephemeral ports are exhausted. This also allows connect() and listen() to
share ports in the following way and may break some applications. So the
ip_autobind_reuse is 0 by default and disables the feature.

  1. setsockopt(sk1, SO_REUSEADDR)
  2. setsockopt(sk2, SO_REUSEADDR)
  3. bind(sk1, saddr, 0)
  4. bind(sk2, saddr, 0)
  5. connect(sk1, daddr)
  6. listen(sk2)

If it is set 1, we can fully utilize the 4-tuples, but we should use
IP_BIND_ADDRESS_NO_PORT for bind()+connect() as possible.

The notable thing is that if all sockets bound to the same port have
both SO_REUSEADDR and SO_REUSEPORT enabled, we can bind sockets to an
ephemeral port and also do listen().

Signed-off-by: Kuniyuki Iwashima 
Signed-off-by: David S. Miller

net/ipv4/sysctl: show tcp_{allowed, available}_congestion_control in non-initial netns

2020-02-19T19:04:31+00:00

It is currenty possible to switch the TCP congestion control algorithm
in non-initial network namespaces:

unshare -U --map-root --net --fork --pid --mount-proc
echo "reno" > /proc/sys/net/ipv4/tcp_congestion_control

works just fine. But currently non-initial network namespaces have no
way of kowing which congestion algorithms are available or allowed other
than through trial and error by writing the names of the algorithms into
the aforementioned file.
Since we already allow changing the congestion algorithm in non-initial
network namespaces by exposing the tcp_congestion_control file there is
no reason to not also expose the
tcp_{allowed,available}_congestion_control files to non-initial network
namespaces. After this change a container with a separate network
namespace will show:

root@f1:~# ls -al /proc/sys/net/ipv4/tcp_* | grep congestion
-rw-r--r-- 1 root root 0 Feb 19 11:54 /proc/sys/net/ipv4/tcp_allowed_congestion_control
-r--r--r-- 1 root root 0 Feb 19 11:54 /proc/sys/net/ipv4/tcp_available_congestion_control
-rw-r--r-- 1 root root 0 Feb 19 11:54 /proc/sys/net/ipv4/tcp_congestion_control

Link: https://github.com/lxc/lxc/issues/3267
Reported-by: Haw Loeung 
Signed-off-by: Christian Brauner 
Signed-off-by: David S. Miller

net-tcp: Disable TCP ssthresh metrics cache by default

2019-12-10T04:17:48+00:00

This patch introduces a sysctl knob "net.ipv4.tcp_no_ssthresh_metrics_save"
that disables TCP ssthresh metrics cache by default. Other parts of TCP
metrics cache, e.g. rtt, cwnd, remain unchanged.

As modern networks becoming more and more dynamic, TCP metrics cache
today often causes more harm than benefits. For example, the same IP
address is often shared by different subscribers behind NAT in residential
networks. Even if the IP address is not shared by different users,
caching the slow-start threshold of a previous short flow using loss-based
congestion control (e.g. cubic) often causes the future longer flows of
the same network path to exit slow-start prematurely with abysmal
throughput.

Caching ssthresh is very risky and can lead to terrible performance.
Therefore it makes sense to make disabling ssthresh caching by
default and opt-in for specific networks by the administrators.
This practice also has worked well for several years of deployment with
CUBIC congestion control at Google.

Acked-by: Eric Dumazet 
Acked-by: Neal Cardwell 
Acked-by: Yuchung Cheng 
Signed-off-by: Kevin(Yudong) Yang 
Signed-off-by: David S. Miller

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2019-11-23T00:27:24+00:00

Minor conflict in drivers/s390/net/qeth_l2_main.c, kept the lock
from commit c8183f548902 ("s390/qeth: fix potential deadlock on
workqueue flush"), removed the code which was removed by commit
9897d583b015 ("s390/qeth: consolidate some duplicated HW cmd code").

Signed-off-by: Jakub Kicinski