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266 Commits (341924049558e5f7c1a148a2c461a417933d35d9)

Author SHA1 Message Date
Eric Dumazet 5f3e2bf008 tcp: add tcp_min_snd_mss sysctl
Some TCP peers announce a very small MSS option in their SYN and/or
SYN/ACK messages.

This forces the stack to send packets with a very high network/cpu
overhead.

Linux has enforced a minimal value of 48. Since this value includes
the size of TCP options, and that the options can consume up to 40
bytes, this means that each segment can include only 8 bytes of payload.

In some cases, it can be useful to increase the minimal value
to a saner value.

We still let the default to 48 (TCP_MIN_SND_MSS), for compatibility
reasons.

Note that TCP_MAXSEG socket option enforces a minimal value
of (TCP_MIN_MSS). David Miller increased this minimal value
in commit c39508d6f1 ("tcp: Make TCP_MAXSEG minimum more correct.")
from 64 to 88.

We might in the future merge TCP_MIN_SND_MSS and TCP_MIN_MSS.

CVE-2019-11479 -- tcp mss hardcoded to 48

Signed-off-by: Eric Dumazet <edumazet@google.com>
Suggested-by: Jonathan Looney <jtl@netflix.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Tyler Hicks <tyhicks@canonical.com>
Cc: Bruce Curtis <brucec@netflix.com>
Cc: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-06-15 18:47:31 -07:00
Eric Dumazet ede61ca474 tcp: add tcp_rx_skb_cache sysctl
Instead of relying on rps_needed, it is safer to use a separate
static key, since we do not want to enable TCP rx_skb_cache
by default. This feature can cause huge increase of memory
usage on hosts with millions of sockets.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-06-14 20:18:28 -07:00
Masanari Iida 2bcd9d842b net-next: net: Fix typos in ip-sysctl.txt
This patch fixes some spelling typos found in ip-sysctl.txt

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-05-21 13:21:08 -07:00
David S. Miller ff24e4980a Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Three trivial overlapping conflicts.

Signed-off-by: David S. Miller <davem@davemloft.net>
2019-05-02 22:14:21 -04:00
David S. Miller b145745fc8 Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec
Steffen Klassert says:

====================
pull request (net): ipsec 2019-04-30

1) Fix an out-of-bound array accesses in __xfrm_policy_unlink.
   From YueHaibing.

2) Reset the secpath on failure in the ESP GRO handlers
   to avoid dereferencing an invalid pointer on error.
   From Myungho Jung.

3) Add and revert a patch that tried to add rcu annotations
   to netns_xfrm. From Su Yanjun.

4) Wait for rcu callbacks before freeing xfrm6_tunnel_spi_kmem.
   From Su Yanjun.

5) Fix forgotten vti4 ipip tunnel deregistration.
   From Jeremy Sowden:

6) Remove some duplicated log messages in vti4.
   From Jeremy Sowden.

7) Don't use IPSEC_PROTO_ANY when flushing states because
   this will flush only IPsec portocol speciffic states.
   IPPROTO_ROUTING states may remain in the lists when
   doing net exit. Fix this by replacing IPSEC_PROTO_ANY
   with zero. From Cong Wang.

8) Add length check for UDP encapsulation to fix "Oversized IP packet"
   warnings on receive side. From Sabrina Dubroca.

9) Fix xfrm interface lookup when the interface is associated to
   a vrf layer 3 master device. From Martin Willi.

10) Reload header pointers after pskb_may_pull() in _decode_session4(),
    otherwise we may read from uninitialized memory.

11) Update the documentation about xfrm[46]_gc_thresh, it
    is not used anymore after the flowcache removal.
    From Nicolas Dichtel.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
2019-04-30 09:11:10 -04:00
David S. Miller 8b44836583 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Two easy cases of overlapping changes.

Signed-off-by: David S. Miller <davem@davemloft.net>
2019-04-25 23:52:29 -04:00
Stephen Suryaputra 0bc1998544 ipv6: Add rate limit mask for ICMPv6 messages
To make ICMPv6 closer to ICMPv4, add ratemask parameter. Since the ICMP
message types use larger numeric values, a simple bitmask doesn't fit.
I use large bitmap. The input and output are the in form of list of
ranges. Set the default to rate limit all error messages but Packet Too
Big. For Packet Too Big, use ratemask instead of hard-coded.

There are functions where icmpv6_xrlim_allow() and icmpv6_global_allow()
aren't called. This patch only adds them to icmpv6_echo_reply().

Rate limiting error messages is mandated by RFC 4443 but RFC 4890 says
that it is also acceptable to rate limit informational messages. Thus,
I removed the current hard-coded behavior of icmpv6_mask_allow() that
doesn't rate limit informational messages.

v2: Add dummy function proc_do_large_bitmap() if CONFIG_PROC_SYSCTL
    isn't defined, expand the description in ip-sysctl.txt and remove
    unnecessary conditional before kfree().
v3: Inline the bitmap instead of dynamically allocated. Still is a
    pointer to it is needed because of the way proc_do_large_bitmap work.

Signed-off-by: Stephen Suryaputra <ssuryaextr@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-04-18 16:58:37 -07:00
ZhangXiaoxu 19fad20d15 ipv4: set the tcp_min_rtt_wlen range from 0 to one day
There is a UBSAN report as below:
UBSAN: Undefined behaviour in net/ipv4/tcp_input.c:2877:56
signed integer overflow:
2147483647 * 1000 cannot be represented in type 'int'
CPU: 3 PID: 0 Comm: swapper/3 Not tainted 5.1.0-rc4-00058-g582549e #1
Call Trace:
 <IRQ>
 dump_stack+0x8c/0xba
 ubsan_epilogue+0x11/0x60
 handle_overflow+0x12d/0x170
 ? ttwu_do_wakeup+0x21/0x320
 __ubsan_handle_mul_overflow+0x12/0x20
 tcp_ack_update_rtt+0x76c/0x780
 tcp_clean_rtx_queue+0x499/0x14d0
 tcp_ack+0x69e/0x1240
 ? __wake_up_sync_key+0x2c/0x50
 ? update_group_capacity+0x50/0x680
 tcp_rcv_established+0x4e2/0xe10
 tcp_v4_do_rcv+0x22b/0x420
 tcp_v4_rcv+0xfe8/0x1190
 ip_protocol_deliver_rcu+0x36/0x180
 ip_local_deliver+0x15b/0x1a0
 ip_rcv+0xac/0xd0
 __netif_receive_skb_one_core+0x7f/0xb0
 __netif_receive_skb+0x33/0xc0
 netif_receive_skb_internal+0x84/0x1c0
 napi_gro_receive+0x2a0/0x300
 receive_buf+0x3d4/0x2350
 ? detach_buf_split+0x159/0x390
 virtnet_poll+0x198/0x840
 ? reweight_entity+0x243/0x4b0
 net_rx_action+0x25c/0x770
 __do_softirq+0x19b/0x66d
 irq_exit+0x1eb/0x230
 do_IRQ+0x7a/0x150
 common_interrupt+0xf/0xf
 </IRQ>

It can be reproduced by:
  echo 2147483647 > /proc/sys/net/ipv4/tcp_min_rtt_wlen

Fixes: f672258391 ("tcp: track min RTT using windowed min-filter")
Signed-off-by: ZhangXiaoxu <zhangxiaoxu5@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-04-17 13:57:11 -07:00
Nicolas Dichtel 837f741165 xfrm: update doc about xfrm[46]_gc_thresh
Those entries are not used anymore.

CC: Florian Westphal <fw@strlen.de>
Fixes: 09c7570480 ("xfrm: remove flow cache")
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
2019-04-12 09:38:23 +02:00
David Ahern 9ab948a91b ipv4: Allow amount of dirty memory from fib resizing to be controllable
fib_trie implementation calls synchronize_rcu when a certain amount of
pages are dirty from freed entries. The number of pages was determined
experimentally in 2009 (commit c3059477fc).

At the current setting, synchronize_rcu is called often -- 51 times in a
second in one test with an average of an 8 msec delay adding a fib entry.
The total impact is a lot of slow down modifying the fib. This is seen
in the output of 'time' - the difference between real time and sys+user.
For example, using 720,022 single path routes and 'ip -batch'[1]:

    $ time ./ip -batch ipv4/routes-1-hops
    real    0m14.214s
    user    0m2.513s
    sys     0m6.783s

So roughly 35% of the actual time to install the routes is from the ip
command getting scheduled out, most notably due to synchronize_rcu (this
is observed using 'perf sched timehist').

This patch makes the amount of dirty memory configurable between 64k where
the synchronize_rcu is called often (small, low end systems that are memory
sensitive) to 64M where synchronize_rcu is called rarely during a large
FIB change (for high end systems with lots of memory). The default is 512kB
which corresponds to the current setting of 128 pages with a 4kB page size.

As an example, at 16MB the worst interval shows 4 calls to synchronize_rcu
in a second blocking for up to 30 msec in a single instance, and a total
of almost 100 msec across the 4 calls in the second. The trade off is
allowing FIB entries to consume more memory in a given time window but
but with much better fib insertion rates (~30% increase in prefixes/sec).
With this patch and net.ipv4.fib_sync_mem set to 16MB, the same batch
file runs in:

    $ time ./ip -batch ipv4/routes-1-hops
    real    0m9.692s
    user    0m2.491s
    sys     0m6.769s

So the dead time is reduced to about 1/2 second or <5% of the real time.

[1] 'ip' modified to not request ACK messages which improves route
    insertion times by about 20%

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-03-21 13:29:53 -07:00
Stephen Suryaputra 0b03a5ca8b ipv6: Add icmp_echo_ignore_anycast for ICMPv6
In addition to icmp_echo_ignore_multicast, there is a need to also
prevent responding to pings to anycast addresses for security.

Signed-off-by: Stephen Suryaputra <ssuryaextr@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-03-20 16:29:37 -07:00
Stephen Suryaputra 03f1eccc7a ipv6: Add icmp_echo_ignore_multicast support for ICMPv6
IPv4 has icmp_echo_ignore_broadcast to prevent responding to broadcast pings.
IPv6 needs a similar mechanism.

v1->v2:
- Remove NET_IPV6_ICMP_ECHO_IGNORE_MULTICAST.

Signed-off-by: Stephen Suryaputra <ssuryaextr@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-03-19 14:29:51 -07:00
David Ahern 58956317c8 neighbor: Improve garbage collection
The existing garbage collection algorithm has a number of problems:

1. The gc algorithm will not evict PERMANENT entries as those entries
   are managed by userspace, yet the existing algorithm walks the entire
   hash table which means it always considers PERMANENT entries when
   looking for entries to evict. In some use cases (e.g., EVPN) there
   can be tens of thousands of PERMANENT entries leading to wasted
   CPU cycles when gc kicks in. As an example, with 32k permanent
   entries, neigh_alloc has been observed taking more than 4 msec per
   invocation.

2. Currently, when the number of neighbor entries hits gc_thresh2 and
   the last flush for the table was more than 5 seconds ago gc kicks in
   walks the entire hash table evicting *all* entries not in PERMANENT
   or REACHABLE state and not marked as externally learned. There is no
   discriminator on when the neigh entry was created or if it just moved
   from REACHABLE to another NUD_VALID state (e.g., NUD_STALE).

   It is possible for entries to be created or for established neighbor
   entries to be moved to STALE (e.g., an external node sends an ARP
   request) right before the 5 second window lapses:

        -----|---------x|----------|-----
            t-5         t         t+5

   If that happens those entries are evicted during gc causing unnecessary
   thrashing on neighbor entries and userspace caches trying to track them.

   Further, this contradicts the description of gc_thresh2 which says
   "Entries older than 5 seconds will be cleared".

   One workaround is to make gc_thresh2 == gc_thresh3 but that negates the
   whole point of having separate thresholds.

3. Clearing *all* neigh non-PERMANENT/REACHABLE/externally learned entries
   when gc_thresh2 is exceeded is over kill and contributes to trashing
   especially during startup.

This patch addresses these problems as follows:

1. Use of a separate list_head to track entries that can be garbage
   collected along with a separate counter. PERMANENT entries are not
   added to this list.

   The gc_thresh parameters are only compared to the new counter, not the
   total entries in the table. The forced_gc function is updated to only
   walk this new gc_list looking for entries to evict.

2. Entries are added to the list head at the tail and removed from the
   front.

3. Entries are only evicted if they were last updated more than 5 seconds
   ago, adhering to the original intent of gc_thresh2.

4. Forced gc is stopped once the number of gc_entries drops below
   gc_thresh2.

5. Since gc checks do not apply to PERMANENT entries, gc levels are skipped
   when allocating a new neighbor for a PERMANENT entry. By extension this
   means there are no explicit limits on the number of PERMANENT entries
   that can be created, but this is no different than FIB entries or FDB
   entries.

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-12-07 16:03:10 -08:00
Eric Dumazet c73e5807e4 tcp: tsq: no longer use limit_output_bytes for paced flows
FQ pacing guarantees that paced packets queued by one flow do not
add head-of-line blocking for other flows.

After TCP GSO conversion, increasing limit_output_bytes to 1 MB is safe,
since this maps to 16 skbs at most in qdisc or device queues.
(or slightly more if some drivers lower {gso_max_segs|size})

We still can queue at most 1 ms worth of traffic (this can be scaled
by wifi drivers if they need to)

Tested:

# ethtool -c eth0 | egrep "tx-usecs:|tx-frames:" # 40 Gbit mlx4 NIC
tx-usecs: 16
tx-frames: 16
# tc qdisc replace dev eth0 root fq
# for f in {1..10};do netperf -P0 -H lpaa24,6 -o THROUGHPUT;done

Before patch:
27711
26118
27107
27377
27712
27388
27340
27117
27278
27509

After patch:
37434
36949
36658
36998
37711
37291
37605
36659
36544
37349

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-11-11 13:57:03 -08:00
Mike Manning 6897445fb1 net: provide a sysctl raw_l3mdev_accept for raw socket lookup with VRFs
Add a sysctl raw_l3mdev_accept to control raw socket lookup in a manner
similar to use of tcp_l3mdev_accept for stream and of udp_l3mdev_accept
for datagram sockets. Have this default to enabled for reasons of
backwards compatibility. This is so as to specify the output device
with cmsg and IP_PKTINFO, but using a socket not bound to the
corresponding VRF. This allows e.g. older ping implementations to be
run with specifying the device but without executing it in the VRF.
If the option is disabled, packets received in a VRF context are only
handled by a raw socket bound to the VRF, and correspondingly packets
in the default VRF are only handled by a socket not bound to any VRF.

Signed-off-by: Mike Manning <mmanning@vyatta.att-mail.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Tested-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-11-07 16:12:38 -08:00
Lorenzo Colitti e2d00e62f2 Documentation: ip-sysctl.txt: Document tcp_fwmark_accept
This patch documents the tcp_fwmark_accept sysctl that was
added in 3.15.

Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-10-29 20:41:52 -07:00
David Ahern 7c6bb7d2fa net/ipv6: Add knob to skip DELROUTE message on device down
Another difference between IPv4 and IPv6 is the generation of RTM_DELROUTE
notifications when a device is taken down (admin down) or deleted. IPv4
does not generate a message for routes evicted by the down or delete;
IPv6 does. A NOS at scale really needs to avoid these messages and have
IPv4 and IPv6 behave similarly, relying on userspace to handle link
notifications and evict the routes.

At this point existing user behavior needs to be preserved. Since
notifications are a global action (not per app) the only way to preserve
existing behavior and allow the messages to be skipped is to add a new
sysctl (net/ipv6/route/skip_notify_on_dev_down) which can be set to
disable the notificatioons.

IPv6 route code already supports the option to skip the message (it is
used for multipath routes for example). Besides the new sysctl we need
to pass the skip_notify setting through the generic fib6_clean and
fib6_walk functions to fib6_clean_node and to set skip_notify on calls
to __ip_del_rt for the addrconf_ifdown path.

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-10-12 09:47:02 -07:00
Maciej Żenczykowski d4ce58082f net-tcp: /proc/sys/net/ipv4/tcp_probe_interval is a u32 not int
(fix documentation and sysctl access to treat it as such)

Tested:
  # zcat /proc/config.gz | egrep ^CONFIG_HZ
  CONFIG_HZ_1000=y
  CONFIG_HZ=1000
  # echo $[(1<<32)/1000 + 1] | tee /proc/sys/net/ipv4/tcp_probe_interval
  4294968
  tee: /proc/sys/net/ipv4/tcp_probe_interval: Invalid argument
  # echo $[(1<<32)/1000] | tee /proc/sys/net/ipv4/tcp_probe_interval
  4294967
  # echo 0 | tee /proc/sys/net/ipv4/tcp_probe_interval
  # echo -1 | tee /proc/sys/net/ipv4/tcp_probe_interval
  -1
  tee: /proc/sys/net/ipv4/tcp_probe_interval: Invalid argument

Signed-off-by: Maciej Żenczykowski <maze@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-09-26 20:33:21 -07:00
Virgile Jarry e6f86b0f7a ipv6: Add icmp_echo_ignore_all support for ICMPv6
Preventing the kernel from responding to ICMP Echo Requests messages
can be useful in several ways. The sysctl parameter
'icmp_echo_ignore_all' can be used to prevent the kernel from
responding to IPv4 ICMP echo requests. For IPv6 pings, such
a sysctl kernel parameter did not exist.

Add the ability to prevent the kernel from responding to IPv6
ICMP echo requests through the use of the following sysctl
parameter : /proc/sys/net/ipv6/icmp/echo_ignore_all.
Update the documentation to reflect this change.

Signed-off-by: Virgile Jarry <virgile@acceis.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-08-13 08:42:25 -07:00
Petr Machata 432e05d328 net: ipv4: Control SKB reprioritization after forwarding
After IPv4 packets are forwarded, the priority of the corresponding SKB
is updated according to the TOS field of IPv4 header. This overrides any
prioritization done earlier by e.g. an skbedit action or ingress-qos-map
defined at a vlan device.

Such overriding may not always be desirable. Even if the packet ends up
being routed, which implies this is an L3 network node, an administrator
may wish to preserve whatever prioritization was done earlier on in the
pipeline.

Therefore introduce a sysctl that controls this behavior. Keep the
default value at 1 to maintain backward-compatible behavior.

Signed-off-by: Petr Machata <petrm@mellanox.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-08-01 09:52:30 -07:00
Sabrina Dubroca f168db5e25 Documentation: ip-sysctl.txt: document addr_gen_mode
addr_gen_mode was introduced in without documentation, add it now.

Fixes: d35a00b8e3 ("net/ipv6: allow sysctl to change link-local address generation mode")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-07-11 22:50:45 -07:00
Flavio Leitner 9c4c325252 skbuff: preserve sock reference when scrubbing the skb.
The sock reference is lost when scrubbing the packet and that breaks
TSQ (TCP Small Queues) and XPS (Transmit Packet Steering) causing
performance impacts of about 50% in a single TCP stream when crossing
network namespaces.

XPS breaks because the queue mapping stored in the socket is not
available, so another random queue might be selected when the stack
needs to transmit something like a TCP ACK, or TCP Retransmissions.
That causes packet re-ordering and/or performance issues.

TSQ breaks because it orphans the packet while it is still in the
host, so packets are queued contributing to the buffer bloat problem.

Preserving the sock reference fixes both issues. The socket is
orphaned anyways in the receiving path before any relevant action
and on TX side the netfilter checks if the reference is local before
use it.

Signed-off-by: Flavio Leitner <fbl@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-06-28 22:21:32 +09:00
Olivier Gayot bb38ccce88 docs: networking: fix minor typos in various documentation files
This patch fixes some typos/misspelling errors in the
Documentation/networking files.

Signed-off-by: Olivier Gayot <olivier.gayot@sigexec.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-06-04 17:21:28 -04:00
Maciej Żenczykowski 79e9fed460 net-tcp: extend tcp_tw_reuse sysctl to enable loopback only optimization
This changes the /proc/sys/net/ipv4/tcp_tw_reuse from a boolean
to an integer.

It now takes the values 0, 1 and 2, where 0 and 1 behave as before,
while 2 enables timewait socket reuse only for sockets that we can
prove are loopback connections:
  ie. bound to 'lo' interface or where one of source or destination
  IPs is 127.0.0.0/8, ::ffff:127.0.0.0/104 or ::1.

This enables quicker reuse of ephemeral ports for loopback connections
- where tcp_tw_reuse is 100% safe from a protocol perspective
(this assumes no artificially induced packet loss on 'lo').

This also makes estblishing many loopback connections *much* faster
(allocating ports out of the first half of the ephemeral port range
is significantly faster, then allocating from the second half)

Without this change in a 32K ephemeral port space my sample program
(it just establishes and closes [::1]:ephemeral -> [::1]:server_port
connections in a tight loop) fails after 32765 connections in 24 seconds.
With it enabled 50000 connections only take 4.7 seconds.

This is particularly problematic for IPv6 where we only have one local
address and cannot play tricks with varying source IP from 127.0.0.0/8
pool.

Signed-off-by: Maciej Żenczykowski <maze@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Wei Wang <weiwan@google.com>
Change-Id: I0377961749979d0301b7b62871a32a4b34b654e1
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-06-04 17:13:35 -04:00
Eric Dumazet 9c21d2fc41 tcp: add tcp_comp_sack_nr sysctl
This per netns sysctl allows for TCP SACK compression fine-tuning.

This limits number of SACK that can be compressed.
Using 0 disables SACK compression.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-05-18 11:40:27 -04:00
Eric Dumazet 6d82aa2420 tcp: add tcp_comp_sack_delay_ns sysctl
This per netns sysctl allows for TCP SACK compression fine-tuning.

Its default value is 1,000,000, or 1 ms to meet TSO autosizing period.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-05-18 11:40:27 -04:00
Yuchung Cheng b38a51fec1 tcp: disable RFC6675 loss detection
This patch disables RFC6675 loss detection and make sysctl
net.ipv4.tcp_recovery = 1 controls a binary choice between RACK
(1) or RFC6675 (0).

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Soheil Hassas Yeganeh <soheil@google.com>
Reviewed-by: Priyaranjan Jha <priyarjha@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-05-17 15:41:28 -04:00
Yuchung Cheng 20b654dfe1 tcp: support DUPACK threshold in RACK
This patch adds support for the classic DUPACK threshold rule
(#DupThresh) in RACK.

When the number of packets SACKed is greater or equal to the
threshold, RACK sets the reordering window to zero which would
immediately mark all the unsacked packets below the highest SACKed
sequence lost. Since this approach is known to not work well with
reordering, RACK only uses it if no reordering has been observed.

The DUPACK threshold rule is a particularly useful extension to the
fast recoveries triggered by RACK reordering timer. For example
data-center transfers where the RTT is much smaller than a timer
tick, or high RTT path where the default RTT/4 may take too long.

Note that this patch differs slightly from RFC6675. RFC6675
considers a packet lost when at least #DupThresh higher-sequence
packets are SACKed.

With RACK, for connections that have seen reordering, RACK
continues to use a dynamically-adaptive time-based reordering
window to detect losses. But for connections on which we have not
yet seen reordering, this patch considers a packet lost when at
least one higher sequence packet is SACKed and the total number
of SACKed packets is at least DupThresh. For example, suppose a
connection has not seen reordering, and sends 10 packets, and
packets 3, 5, 7 are SACKed. RFC6675 considers packets 1 and 2
lost. RACK considers packets 1, 2, 4, 6 lost.

There is some small risk of spurious retransmits here due to
reordering. However, this is mostly limited to the first flight of
a connection on which the sender receives SACKs from reordering.
And RFC 6675 and FACK loss detection have a similar risk on the
first flight with reordering (it's just that the risk of spurious
retransmits from reordering was slightly narrower for those older
algorithms due to the margin of 3*MSS).

Also the minimum reordering window is reduced from 1 msec to 0
to recover quicker on short RTT transfers. Therefore RACK is more
aggressive in marking packets lost during recovery to reduce the
reordering window timeouts.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Soheil Hassas Yeganeh <soheil@google.com>
Reviewed-by: Priyaranjan Jha <priyarjha@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-05-17 15:41:28 -04:00
David S. Miller a7b15ab887 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Overlapping changes in selftests Makefile.

Signed-off-by: David S. Miller <davem@davemloft.net>
2018-05-04 09:58:56 -04:00
Ahmed Abdelsalam a6dc6670cd ipv6: sr: Add documentation for seg_flowlabel sysctl
This patch adds a documentation for seg_flowlabel sysctl into
Documentation/networking/ip-sysctl.txt

Signed-off-by: Ahmed Abdelsalam <amsalam20@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-04-27 20:23:56 -04:00
Linus Torvalds 79a17dd9d2 Staging fixes for 4.17-rc3
Here are 2 staging driver fixups for 4.17-rc3.
 
 The first is the remaining stragglers of the irda code removal that you
 pointed out during the merge window.  The second is a fix for the
 wilc1000 driver due to a patch that got merged in 4.17-rc1.
 
 Both of these have been in linux-next for a while with no reported
 issues.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'staging-4.17-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging

Pull staging fixes from Greg KH:
 "Here are two staging driver fixups for 4.17-rc3.

  The first is the remaining stragglers of the irda code removal that
  you pointed out during the merge window. The second is a fix for the
  wilc1000 driver due to a patch that got merged in 4.17-rc1.

  Both of these have been in linux-next for a while with no reported
  issues"

* tag 'staging-4.17-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging:
  staging: wilc1000: fix NULL pointer exception in host_int_parse_assoc_resp_info()
  staging: irda: remove remaining remants of irda code removal
2018-04-27 09:37:12 -07:00
Olivier Gayot ab913455dd docs: ip-sysctl.txt: fix name of some ipv6 variables
The name of the following proc/sysctl entries were incorrectly
documented:

    /proc/sys/net/ipv6/conf/<interface>/max_dst_opts_number
    /proc/sys/net/ipv6/conf/<interface>/max_hbt_opts_number
    /proc/sys/net/ipv6/conf/<interface>/max_dst_opts_length
    /proc/sys/net/ipv6/conf/<interface>/max_hbt_length

Their name was set to the name of the symbol in the .data field of the
control table instead of their .proc name.

Signed-off-by: Olivier Gayot <olivier.gayot@sigexec.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-04-19 15:20:09 -04:00
Greg Kroah-Hartman edf5c17d86 staging: irda: remove remaining remants of irda code removal
There were some documentation locations that irda was mentioned, as well
as an old MAINTAINERS entry and the networking sysctl entries.  Clean
these all out as this stuff really is finally gone.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-04-16 11:26:49 +02:00
Eric Dumazet 3e67f106f6 inet: frags: break the 2GB limit for frags storage
Some users are willing to provision huge amounts of memory to be able
to perform reassembly reasonnably well under pressure.

Current memory tracking is using one atomic_t and integers.

Switch to atomic_long_t so that 64bit arches can use more than 2GB,
without any cost for 32bit arches.

Note that this patch avoids an overflow error, if high_thresh was set
to ~2GB, since this test in inet_frag_alloc() was never true :

if (... || frag_mem_limit(nf) > nf->high_thresh)

Tested:

$ echo 16000000000 >/proc/sys/net/ipv4/ipfrag_high_thresh

<frag DDOS>

$ grep FRAG /proc/net/sockstat
FRAG: inuse 14705885 memory 16000002880

$ nstat -n ; sleep 1 ; nstat | grep Reas
IpReasmReqds                    3317150            0.0
IpReasmFails                    3317112            0.0

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-03-31 23:25:39 -04:00
Eric Dumazet 648700f76b inet: frags: use rhashtables for reassembly units
Some applications still rely on IP fragmentation, and to be fair linux
reassembly unit is not working under any serious load.

It uses static hash tables of 1024 buckets, and up to 128 items per bucket (!!!)

A work queue is supposed to garbage collect items when host is under memory
pressure, and doing a hash rebuild, changing seed used in hash computations.

This work queue blocks softirqs for up to 25 ms when doing a hash rebuild,
occurring every 5 seconds if host is under fire.

Then there is the problem of sharing this hash table for all netns.

It is time to switch to rhashtables, and allocate one of them per netns
to speedup netns dismantle, since this is a critical metric these days.

Lookup is now using RCU. A followup patch will even remove
the refcount hold/release left from prior implementation and save
a couple of atomic operations.

Before this patch, 16 cpus (16 RX queue NIC) could not handle more
than 1 Mpps frags DDOS.

After the patch, I reach 9 Mpps without any tuning, and can use up to 2GB
of storage for the fragments (exact number depends on frags being evicted
after timeout)

$ grep FRAG /proc/net/sockstat
FRAG: inuse 1966916 memory 2140004608

A followup patch will change the limits for 64bit arches.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Florian Westphal <fw@strlen.de>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Alexander Aring <alex.aring@gmail.com>
Cc: Stefan Schmidt <stefan@osg.samsung.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-03-31 23:25:39 -04:00
Lorenzo Bianconi 2f0aaf7fb1 Documentation: ip-sysctl.txt: clarify disable_ipv6
Clarify that when disable_ipv6 is enabled even the ipv6 routes
are deleted for the selected interface and from now it will not
be possible to add addresses/routes to that interface

Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-03-30 12:20:52 -04:00
Tonghao Zhang 320bd6de79 doc: Change the udp/sctp rmem/wmem default value.
The SK_MEM_QUANTUM was changed from PAGE_SIZE to 4096.

Signed-off-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-03-16 12:03:30 -04:00
David Ahern b4bac172e9 net/ipv6: Add support for path selection using hash of 5-tuple
Some operators prefer IPv6 path selection to use a standard 5-tuple
hash rather than just an L3 hash with the flow the label. To that end
add support to IPv6 for multipath hash policy similar to bf4e0a3db9
("net: ipv4: add support for ECMP hash policy choice"). The default
is still L3 which covers source and destination addresses along with
flow label and IPv6 protocol.

Signed-off-by: David Ahern <dsahern@gmail.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Tested-by: Ido Schimmel <idosch@mellanox.com>
Reviewed-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-03-04 13:04:23 -05:00
Tonghao Zhang a61a86f8db doc: Change the min default value of tcp_wmem/tcp_rmem.
The SK_MEM_QUANTUM was changed from PAGE_SIZE to 4096. And the
tcp_wmem/tcp_rmem min default values are 4096.

Fixes: bd68a2a854 ("net: set SK_MEM_QUANTUM to 4096")
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-02-05 10:05:49 -05:00
Yuchung Cheng 7268586baa tcp: pause Fast Open globally after third consecutive timeout
Prior to this patch, active Fast Open is paused on a specific
destination IP address if the previous connections to the
IP address have experienced recurring timeouts . But recent
experiments by Microsoft (https://goo.gl/cykmn7) and Mozilla
browsers indicate the isssue is often caused by broken middle-boxes
sitting close to the client. Therefore it is much better user
experience if Fast Open is disabled out-right globally to avoid
experiencing further timeouts on connections toward other
destinations.

This patch changes the destination-IP disablement to global
disablement if a connection experiencing recurring timeouts
or aborts due to timeout.  Repeated incidents would still
exponentially increase the pause time, starting from an hour.
This is extremely conservative but an unfortunate compromise to
minimize bad experience due to broken middle-boxes.

Reported-by: Dragana Damjanovic <ddamjanovic@mozilla.com>
Reported-by: Patrick McManus <mcmanus@ducksong.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Reviewed-by: Wei Wang <weiwan@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-12-13 15:51:12 -05:00
Yuchung Cheng 713bafea92 tcp: retire FACK loss detection
FACK loss detection has been disabled by default and the
successor RACK subsumed FACK and can handle reordering better.
This patch removes FACK to simplify TCP loss recovery.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Soheil Hassas Yeganeh <soheil@google.com>
Reviewed-by: Priyaranjan Jha <priyarjha@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-11-11 18:53:16 +09:00
Maciej Żenczykowski 2210d6b2f2 net: ipv6: sysctl to specify IPv6 ND traffic class
Add a per-device sysctl to specify the default traffic class to use for
kernel originated IPv6 Neighbour Discovery packets.

Currently this includes:

  - Router Solicitation (ICMPv6 type 133)
    ndisc_send_rs() -> ndisc_send_skb() -> ip6_nd_hdr()

  - Neighbour Solicitation (ICMPv6 type 135)
    ndisc_send_ns() -> ndisc_send_skb() -> ip6_nd_hdr()

  - Neighbour Advertisement (ICMPv6 type 136)
    ndisc_send_na() -> ndisc_send_skb() -> ip6_nd_hdr()

  - Redirect (ICMPv6 type 137)
    ndisc_send_redirect() -> ndisc_send_skb() -> ip6_nd_hdr()

and if the kernel ever gets around to generating RA's,
it would presumably also include:

  - Router Advertisement (ICMPv6 type 134)
    (radvd daemon could pick up on the kernel setting and use it)

Interface drivers may examine the Traffic Class value and translate
the DiffServ Code Point into a link-layer appropriate traffic
prioritization scheme.  An example of mapping IETF DSCP values to
IEEE 802.11 User Priority values can be found here:

    https://tools.ietf.org/html/draft-ietf-tsvwg-ieee-802-11

The expected primary use case is to properly prioritize ND over wifi.

Testing:
  jzem22:~# cat /proc/sys/net/ipv6/conf/eth0/ndisc_tclass
  0
  jzem22:~# echo -1 > /proc/sys/net/ipv6/conf/eth0/ndisc_tclass
  -bash: echo: write error: Invalid argument
  jzem22:~# echo 256 > /proc/sys/net/ipv6/conf/eth0/ndisc_tclass
  -bash: echo: write error: Invalid argument
  jzem22:~# echo 0 > /proc/sys/net/ipv6/conf/eth0/ndisc_tclass
  jzem22:~# echo 255 > /proc/sys/net/ipv6/conf/eth0/ndisc_tclass
  jzem22:~# cat /proc/sys/net/ipv6/conf/eth0/ndisc_tclass
  255
  jzem22:~# echo 34 > /proc/sys/net/ipv6/conf/eth0/ndisc_tclass
  jzem22:~# cat /proc/sys/net/ipv6/conf/eth0/ndisc_tclass
  34

  jzem22:~# echo $[0xDC] > /proc/sys/net/ipv6/conf/eth0/ndisc_tclass
  jzem22:~# tcpdump -v -i eth0 icmp6 and src host jzem22.pgc and dst host fe80::1
  tcpdump: listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes
  IP6 (class 0xdc, hlim 255, next-header ICMPv6 (58) payload length: 24)
  jzem22.pgc > fe80::1: [icmp6 sum ok] ICMP6, neighbor advertisement,
  length 24, tgt is jzem22.pgc, Flags [solicited]

(based on original change written by Erik Kline, with minor changes)

v2: fix 'suspicious rcu_dereference_check() usage'
    by explicitly grabbing the rcu_read_lock.

Cc: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: Erik Kline <ek@google.com>
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-11-11 15:13:02 +09:00
Priyaranjan Jha 1f2556916d tcp: higher throughput under reordering with adaptive RACK reordering wnd
Currently TCP RACK loss detection does not work well if packets are
being reordered beyond its static reordering window (min_rtt/4).Under
such reordering it may falsely trigger loss recoveries and reduce TCP
throughput significantly.

This patch improves that by increasing and reducing the reordering
window based on DSACK, which is now supported in major TCP implementations.
It makes RACK's reo_wnd adaptive based on DSACK and no. of recoveries.

- If DSACK is received, increment reo_wnd by min_rtt/4 (upper bounded
  by srtt), since there is possibility that spurious retransmission was
  due to reordering delay longer than reo_wnd.

- Persist the current reo_wnd value for TCP_RACK_RECOVERY_THRESH (16)
  no. of successful recoveries (accounts for full DSACK-based loss
  recovery undo). After that, reset it to default (min_rtt/4).

- At max, reo_wnd is incremented only once per rtt. So that the new
  DSACK on which we are reacting, is due to the spurious retx (approx)
  after the reo_wnd has been updated last time.

- reo_wnd is tracked in terms of steps (of min_rtt/4), rather than
  absolute value to account for change in rtt.

In our internal testing, we observed significant increase in throughput,
in scenarios where reordering exceeds min_rtt/4 (previous static value).

Signed-off-by: Priyaranjan Jha <priyarjha@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-11-05 23:15:42 +09:00
Tom Herbert 47d3d7ac65 ipv6: Implement limits on Hop-by-Hop and Destination options
RFC 8200 (IPv6) defines Hop-by-Hop options and Destination options
extension headers. Both of these carry a list of TLVs which is
only limited by the maximum length of the extension header (2048
bytes). By the spec a host must process all the TLVs in these
options, however these could be used as a fairly obvious
denial of service attack. I think this could in fact be
a significant DOS vector on the Internet, one mitigating
factor might be that many FWs drop all packets with EH (and
obviously this is only IPv6) so an Internet wide attack might not
be so effective (yet!).

By my calculation, the worse case packet with TLVs in a standard
1500 byte MTU packet that would be processed by the stack contains
1282 invidual TLVs (including pad TLVS) or 724 two byte TLVs. I
wrote a quick test program that floods a whole bunch of these
packets to a host and sure enough there is substantial time spent
in ip6_parse_tlv. These packets contain nothing but unknown TLVS
(that are ignored), TLV padding, and bogus UDP header with zero
payload length.

  25.38%  [kernel]                    [k] __fib6_clean_all
  21.63%  [kernel]                    [k] ip6_parse_tlv
   4.21%  [kernel]                    [k] __local_bh_enable_ip
   2.18%  [kernel]                    [k] ip6_pol_route.isra.39
   1.98%  [kernel]                    [k] fib6_walk_continue
   1.88%  [kernel]                    [k] _raw_write_lock_bh
   1.65%  [kernel]                    [k] dst_release

This patch adds configurable limits to Destination and Hop-by-Hop
options. There are three limits that may be set:
  - Limit the number of options in a Hop-by-Hop or Destination options
    extension header.
  - Limit the byte length of a Hop-by-Hop or Destination options
    extension header.
  - Disallow unrecognized options in a Hop-by-Hop or Destination
    options extension header.

The limits are set in corresponding sysctls:

  ipv6.sysctl.max_dst_opts_cnt
  ipv6.sysctl.max_hbh_opts_cnt
  ipv6.sysctl.max_dst_opts_len
  ipv6.sysctl.max_hbh_opts_len

If a max_*_opts_cnt is less than zero then unknown TLVs are disallowed.
The number of known TLVs that are allowed is the absolute value of
this number.

If a limit is exceeded when processing an extension header the packet is
dropped.

Default values are set to 8 for options counts, and set to INT_MAX
for maximum length. Note the choice to limit options to 8 is an
arbitrary guess (roughly based on the fact that the stack supports
three HBH options and just one destination option).

These limits have being proposed in draft-ietf-6man-rfc6434-bis.

Tested (by Martin Lau)

I tested out 1 thread (i.e. one raw_udp process).

I changed the net.ipv6.max_dst_(opts|hbh)_number between 8 to 2048.
With sysctls setting to 2048, the softirq% is packed to 100%.
With 8, the softirq% is almost unnoticable from mpstat.

v2;
  - Code and documention cleanup.
  - Change references of RFC2460 to be RFC8200.
  - Add reference to RFC6434-bis where the limits will be in standard.

Signed-off-by: Tom Herbert <tom@quantonium.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-11-03 09:50:22 +09:00
Matteo Croce 35e015e1f5 ipv6: fix net.ipv6.conf.all interface DAD handlers
Currently, writing into
net.ipv6.conf.all.{accept_dad,use_optimistic,optimistic_dad} has no effect.
Fix handling of these flags by:

- using the maximum of global and per-interface values for the
  accept_dad flag. That is, if at least one of the two values is
  non-zero, enable DAD on the interface. If at least one value is
  set to 2, enable DAD and disable IPv6 operation on the interface if
  MAC-based link-local address was found

- using the logical OR of global and per-interface values for the
  optimistic_dad flag. If at least one of them is set to one, optimistic
  duplicate address detection (RFC 4429) is enabled on the interface

- using the logical OR of global and per-interface values for the
  use_optimistic flag. If at least one of them is set to one,
  optimistic addresses won't be marked as deprecated during source address
  selection on the interface.

While at it, as we're modifying the prototype for ipv6_use_optimistic_addr(),
drop inline, and let the compiler decide.

Fixes: 7fd2561e4e ("net: ipv6: Add a sysctl to make optimistic addresses useful candidates")
Signed-off-by: Matteo Croce <mcroce@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-09-19 16:44:02 -07:00
Eric Dumazet eaa72dc474 neigh: increase queue_len_bytes to match wmem_default
Florian reported UDP xmit drops that could be root caused to the
too small neigh limit.

Current limit is 64 KB, meaning that even a single UDP socket would hit
it, since its default sk_sndbuf comes from net.core.wmem_default
(~212992 bytes on 64bit arches).

Once ARP/ND resolution is in progress, we should allow a little more
packets to be queued, at least for one producer.

Once neigh arp_queue is filled, a rogue socket should hit its sk_sndbuf
limit and either block in sendmsg() or return -EAGAIN.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-08-29 16:10:50 -07:00
Jakub Sitnicki 22b6722bfa ipv6: Add sysctl for per namespace flow label reflection
Reflecting IPv6 Flow Label at server nodes is useful in environments
that employ multipath routing to load balance the requests. As "IPv6
Flow Label Reflection" standard draft [1] points out - ICMPv6 PTB error
messages generated in response to a downstream packets from the server
can be routed by a load balancer back to the original server without
looking at transport headers, if the server applies the flow label
reflection. This enables the Path MTU Discovery past the ECMP router in
load-balance or anycast environments where each server node is reachable
by only one path.

Introduce a sysctl to enable flow label reflection per net namespace for
all newly created sockets. Same could be earlier achieved only per
socket by setting the IPV6_FL_F_REFLECT flag for the IPV6_FLOWLABEL_MGR
socket option.

[1] https://tools.ietf.org/html/draft-wang-6man-flow-label-reflection-01

Signed-off-by: Jakub Sitnicki <jkbs@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-08-24 18:05:43 -07:00
Florian Westphal b6690b1438 tcp: remove low_latency sysctl
Was only checked by the removed prequeue code.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-07-31 14:37:49 -07:00
Florian Westphal 3c2a89ddc1 net: xfrm: revert to lower xfrm dst gc limit
revert c386578f1c ("xfrm: Let the flowcache handle its size by default.").

Once we remove flow cache, we don't have a flow cache limit anymore.
We must not allow (virtually) unlimited allocations of xfrm dst entries.
Revert back to the old xfrm dst gc limits.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-07-18 11:13:41 -07:00
Wei Wang cf1ef3f071 net/tcp_fastopen: Disable active side TFO in certain scenarios
Middlebox firewall issues can potentially cause server's data being
blackholed after a successful 3WHS using TFO. Following are the related
reports from Apple:
https://www.nanog.org/sites/default/files/Paasch_Network_Support.pdf
Slide 31 identifies an issue where the client ACK to the server's data
sent during a TFO'd handshake is dropped.
C ---> syn-data ---> S
C <--- syn/ack ----- S
C (accept & write)
C <---- data ------- S
C ----- ACK -> X     S
		[retry and timeout]

https://www.ietf.org/proceedings/94/slides/slides-94-tcpm-13.pdf
Slide 5 shows a similar situation that the server's data gets dropped
after 3WHS.
C ---- syn-data ---> S
C <--- syn/ack ----- S
C ---- ack --------> S
S (accept & write)
C?  X <- data ------ S
		[retry and timeout]

This is the worst failure b/c the client can not detect such behavior to
mitigate the situation (such as disabling TFO). Failing to proceed, the
application (e.g., SSL library) may simply timeout and retry with TFO
again, and the process repeats indefinitely.

The proposed solution is to disable active TFO globally under the
following circumstances:
1. client side TFO socket detects out of order FIN
2. client side TFO socket receives out of order RST

We disable active side TFO globally for 1hr at first. Then if it
happens again, we disable it for 2h, then 4h, 8h, ...
And we reset the timeout to 1hr if a client side TFO sockets not opened
on loopback has successfully received data segs from server.
And we examine this condition during close().

The rational behind it is that when such firewall issue happens,
application running on the client should eventually close the socket as
it is not able to get the data it is expecting. Or application running
on the server should close the socket as it is not able to receive any
response from client.
In both cases, out of order FIN or RST will get received on the client
given that the firewall will not block them as no data are in those
frames.
And we want to disable active TFO globally as it helps if the middle box
is very close to the client and most of the connections are likely to
fail.

Also, add a debug sysctl:
  tcp_fastopen_blackhole_detect_timeout_sec:
    the initial timeout to use when firewall blackhole issue happens.
    This can be set and read.
    When setting it to 0, it means to disable the active disable logic.

Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-04-24 14:27:17 -04:00