linux-stable.git/net/ipv4, branch v5.3.7

udp: only do GSO if # of segs > 1

2019-10-07T17:01:51+00:00

[ Upstream commit 4094871db1d65810acab3d57f6089aa39ef7f648 ]

Prior to this change an application sending <= 1MSS worth of data and
enabling UDP GSO would fail if the system had SW GSO enabled, but the
same send would succeed if HW GSO offload is enabled. In addition to this
inconsistency the error in the SW GSO case does not get back to the
application if sending out of a real device so the user is unaware of this
failure.

With this change we only perform GSO if the # of segments is > 1 even
if the application has enabled segmentation. I've also updated the
relevant udpgso selftests.

Fixes: bec1f6f69736 ("udp: generate gso with UDP_SEGMENT")
Signed-off-by: Josh Hunt 
Reviewed-by: Willem de Bruijn 
Reviewed-by: Alexander Duyck 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

tcp: adjust rto_base in retransmits_timed_out()

2019-10-07T17:01:51+00:00

[ Upstream commit 3256a2d6ab1f71f9a1bd2d7f6f18eb8108c48d17 ]

The cited commit exposed an old retransmits_timed_out() bug
which assumed it could call tcp_model_timeout() with
TCP_RTO_MIN as rto_base for all states.

But flows in SYN_SENT or SYN_RECV state uses a different
RTO base (1 sec instead of 200 ms, unless BPF choses
another value)

This caused a reduction of SYN retransmits from 6 to 4 with
the default /proc/sys/net/ipv4/tcp_syn_retries value.

Fixes: a41e8a88b06e ("tcp: better handle TCP_USER_TIMEOUT in SYN_SENT state")
Signed-off-by: Eric Dumazet 
Cc: Yuchung Cheng 
Cc: Marek Majkowski 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

udp: fix gso_segs calculations

2019-10-07T17:01:50+00:00

[ Upstream commit 44b321e5020d782ad6e8ae8183f09b163be6e6e2 ]

Commit dfec0ee22c0a ("udp: Record gso_segs when supporting UDP segmentation offload")
added gso_segs calculation, but incorrectly got sizeof() the pointer and
not the underlying data type. In addition let's fix the v6 case.

Fixes: bec1f6f69736 ("udp: generate gso with UDP_SEGMENT")
Fixes: dfec0ee22c0a ("udp: Record gso_segs when supporting UDP segmentation offload")
Signed-off-by: Josh Hunt 
Reviewed-by: Alexander Duyck 
Acked-by: Willem de Bruijn 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

net: ipv4: avoid mixed n_redirects and rate_tokens usage

2019-10-07T17:01:47+00:00

[ Upstream commit b406472b5ad79ede8d10077f0c8f05505ace8b6d ]

Since commit c09551c6ff7f ("net: ipv4: use a dedicated counter
for icmp_v4 redirect packets") we use 'n_redirects' to account
for redirect packets, but we still use 'rate_tokens' to compute
the redirect packets exponential backoff.

If the device sent to the relevant peer any ICMP error packet
after sending a redirect, it will also update 'rate_token' according
to the leaking bucket schema; typically 'rate_token' will raise
above BITS_PER_LONG and the redirect packets backoff algorithm
will produce undefined behavior.

Fix the issue using 'n_redirects' to compute the exponential backoff
in ip_rt_send_redirect().

Note that we still clear rate_tokens after a redirect silence period,
to avoid changing an established behaviour.

The root cause predates git history; before the mentioned commit in
the critical scenario, the kernel stopped sending redirects, after
the mentioned commit the behavior more randomic.

Reported-by: Xiumei Mu 
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Fixes: c09551c6ff7f ("net: ipv4: use a dedicated counter for icmp_v4 redirect packets")
Signed-off-by: Paolo Abeni 
Acked-by: Lorenzo Bianconi 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

erspan: remove the incorrect mtu limit for erspan

2019-10-07T17:01:46+00:00

[ Upstream commit 0e141f757b2c78c983df893e9993313e2dc21e38 ]

erspan driver calls ether_setup(), after commit 61e84623ace3
("net: centralize net_device min/max MTU checking"), the range
of mtu is [min_mtu, max_mtu], which is [68, 1500] by default.

It causes the dev mtu of the erspan device to not be greater
than 1500, this limit value is not correct for ipgre tap device.

Tested:
Before patch:
# ip link set erspan0 mtu 1600
Error: mtu greater than device maximum.
After patch:
# ip link set erspan0 mtu 1600
# ip -d link show erspan0
21: erspan0@NONE:  mtu 1600 qdisc noop state DOWN
mode DEFAULT group default qlen 1000
    link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff promiscuity 0 minmtu 68 maxmtu 0

Fixes: 61e84623ace3 ("net: centralize net_device min/max MTU checking")
Signed-off-by: Haishuang Yan 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

tcp: better handle TCP_USER_TIMEOUT in SYN_SENT state

2019-10-05T13:11:22+00:00

[ Upstream commit a66b10c05ee2d744189e9a2130394b070883d289 ]

Yuchung Cheng and Marek Majkowski independently reported a weird
behavior of TCP_USER_TIMEOUT option when used at connect() time.

When the TCP_USER_TIMEOUT is reached, tcp_write_timeout()
believes the flow should live, and the following condition
in tcp_clamp_rto_to_user_timeout() programs one jiffie timers :

    remaining = icsk->icsk_user_timeout - elapsed;
    if (remaining <= 0)
        return 1; /* user timeout has passed; fire ASAP */

This silly situation ends when the max syn rtx count is reached.

This patch makes sure we honor both TCP_SYNCNT and TCP_USER_TIMEOUT,
avoiding these spurious SYN packets.

Fixes: b701a99e431d ("tcp: Add tcp_clamp_rto_to_user_timeout() helper to improve accuracy")
Signed-off-by: Eric Dumazet 
Reported-by: Yuchung Cheng 
Reported-by: Marek Majkowski 
Cc: Jon Maxwell 
Link: https://marc.info/?l=linux-netdev&m=156940118307949&w=2
Acked-by: Jon Maxwell 
Tested-by: Marek Majkowski 
Signed-off-by: Marek Majkowski 
Acked-by: Yuchung Cheng 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

ipv4: Revert removal of rt_uses_gateway

2019-10-05T13:11:20+00:00

[ Upstream commit 77d5bc7e6a6cf8bbeca31aab7f0c5449a5eee762 ]

Julian noted that rt_uses_gateway has a more subtle use than 'is gateway
set':
    https://lore.kernel.org/netdev/alpine.LFD.2.21.1909151104060.2546@ja.home.ssi.bg/

Revert that part of the commit referenced in the Fixes tag.

Currently, there are no u8 holes in 'struct rtable'. There is a 4-byte hole
in the second cacheline which contains the gateway declaration. So move
rt_gw_family down to the gateway declarations since they are always used
together, and then re-use that u8 for rt_uses_gateway. End result is that
rtable size is unchanged.

Fixes: 1550c171935d ("ipv4: Prepare rtable for IPv6 gateway")
Reported-by: Julian Anastasov 
Signed-off-by: David Ahern 
Reviewed-by: Julian Anastasov 
Signed-off-by: Jakub Kicinski 
Signed-off-by: Greg Kroah-Hartman

tcp_bbr: fix quantization code to not raise cwnd if not probing bandwidth

2019-10-05T13:11:18+00:00

[ Upstream commit 6b3656a60f2067738d1a423328199720806f0c44 ]

There was a bug in the previous logic that attempted to ensure gain cycling
gets inflight above BDP even for small BDPs. This code correctly raised and
lowered target inflight values during the gain cycle. And this code
correctly ensured that cwnd was raised when probing bandwidth. However, it
did not correspondingly ensure that cwnd was *not* raised in this way when
*not* probing for bandwidth. The result was that small-BDP flows that were
always cwnd-bound could go for many cycles with a fixed cwnd, and not probe
or yield bandwidth at all. This meant that multiple small-BDP flows could
fail to converge in their bandwidth allocations.

Fixes: 3c346b233c68 ("tcp_bbr: fix bw probing to raise in-flight data for very small BDPs")
Signed-off-by: Kevin(Yudong) Yang 
Acked-by: Neal Cardwell 
Acked-by: Yuchung Cheng 
Acked-by: Soheil Hassas Yeganeh 
Acked-by: Priyaranjan Jha 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

udp: correct reuseport selection with connected sockets

2019-09-21T05:19:39+00:00

[ Upstream commit acdcecc61285faed359f1a3568c32089cc3a8329 ]

UDP reuseport groups can hold a mix unconnected and connected sockets.
Ensure that connections only receive all traffic to their 4-tuple.

Fast reuseport returns on the first reuseport match on the assumption
that all matches are equal. Only if connections are present, return to
the previous behavior of scoring all sockets.

Record if connections are present and if so (1) treat such connected
sockets as an independent match from the group, (2) only return
2-tuple matches from reuseport and (3) do not return on the first
2-tuple reuseport match to allow for a higher scoring match later.

New field has_conns is set without locks. No other fields in the
bitmap are modified at runtime and the field is only ever set
unconditionally, so an RMW cannot miss a change.

Fixes: e32ea7e74727 ("soreuseport: fast reuseport UDP socket selection")
Link: http://lkml.kernel.org/r/CA+FuTSfRP09aJNYRt04SS6qj22ViiOEWaWmLAwX0psk8-PGNxw@mail.gmail.com
Signed-off-by: Willem de Bruijn 
Acked-by: Paolo Abeni 
Acked-by: Craig Gallek 
Signed-off-by: Willem de Bruijn 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

tcp: fix tcp_ecn_withdraw_cwr() to clear TCP_ECN_QUEUE_CWR

2019-09-11T22:53:18+00:00

Fix tcp_ecn_withdraw_cwr() to clear the correct bit:
TCP_ECN_QUEUE_CWR.

Rationale: basically, TCP_ECN_DEMAND_CWR is a bit that is purely about
the behavior of data receivers, and deciding whether to reflect
incoming IP ECN CE marks as outgoing TCP th->ece marks. The
TCP_ECN_QUEUE_CWR bit is purely about the behavior of data senders,
and deciding whether to send CWR. The tcp_ecn_withdraw_cwr() function
is only called from tcp_undo_cwnd_reduction() by data senders during
an undo, so it should zero the sender-side state,
TCP_ECN_QUEUE_CWR. It does not make sense to stop the reflection of
incoming CE bits on incoming data packets just because outgoing
packets were spuriously retransmitted.

The bug has been reproduced with packetdrill to manifest in a scenario
with RFC3168 ECN, with an incoming data packet with CE bit set and
carrying a TCP timestamp value that causes cwnd undo. Before this fix,
the IP CE bit was ignored and not reflected in the TCP ECE header bit,
and sender sent a TCP CWR ('W') bit on the next outgoing data packet,
even though the cwnd reduction had been undone.  After this fix, the
sender properly reflects the CE bit and does not set the W bit.

Note: the bug actually predates 2005 git history; this Fixes footer is
chosen to be the oldest SHA1 I have tested (from Sep 2007) for which
the patch applies cleanly (since before this commit the code was in a
.h file).

Fixes: bdf1ee5d3bd3 ("[TCP]: Move code from tcp_ecn.h to tcp*.c and tcp.h & remove it")
Signed-off-by: Neal Cardwell 
Acked-by: Yuchung Cheng 
Acked-by: Soheil Hassas Yeganeh 
Cc: Eric Dumazet 
Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller