validation of SEG.ACK as the first step. If the ACK is not acceptable,
a RST segment should be sent and the segment should be dropped.
Up to now, the segment was partially processed.
This patch moves the check for the SEG.ACK validation up to the front
as required.
Reviewed by: hiren, gnn
MFC after: 1 week
Sponsored by: Netflix, Inc.
Differential Revision: https://reviews.freebsd.org/D10424
for example not in SYN-SENT.
This patch adds code to check the sysctl variable in other states than
LISTEN.
Thanks to ae and gnn for providing comments.
Reviewed by: gnn
MFC after: 1 week
Sponsored by: Netflix, Inc.
Differential Revision: https://reviews.freebsd.org/D9894
Switched from using timestamps to RTT estimates when performing TCP receive
buffer auto resizing, as not all hosts support / enable TCP timestamps.
Disabled reset of receive buffer auto scaling when not in bulk receive mode,
which gives an extra 20% performance increase.
Also extracted auto resizing to a common method shared between standard and
fastpath modules.
With this AWS S3 downloads at ~17ms latency on a 1Gbps connection jump from
~3MB/s to ~100MB/s using the default settings.
Reviewed by: lstewart, gnn
MFC after: 2 weeks
Relnotes: Yes
Sponsored by: Multiplay
Differential Revision: https://reviews.freebsd.org/D9668
Renumber cluase 4 to 3, per what everybody else did when BSD granted
them permission to remove clause 3. My insistance on keeping the same
numbering for legal reasons is too pedantic, so give up on that point.
Submitted by: Jan Schaumann <jschauma@stevens.edu>
Pull Request: https://github.com/freebsd/freebsd/pull/96
If the TCP stack has retransmitted more than 1/4 of the total
number of retransmits before a connection drop, it decides that
its current RTT estimate is hopelessly out of date and decides
to recalculate it from scratch starting with the next ACK.
Unfortunately, it implements this by zeroing out the current RTT
estimate. Drop this hack entirely, as it makes it significantly more
difficult to debug connection issues. Instead check for excessive
retransmits at the point where srtt is updated from an ACK being
received. If we've exceeded 1/4 of the maximum retransmits,
discard the previous srtt estimate and replace it with the latest
rtt measurement.
Differential Revision: https://reviews.freebsd.org/D9519
Reviewed by: gnn
Sponsored by: Dell EMC Isilon
Small summary
-------------
o Almost all IPsec releated code was moved into sys/netipsec.
o New kernel modules added: ipsec.ko and tcpmd5.ko. New kernel
option IPSEC_SUPPORT added. It enables support for loading
and unloading of ipsec.ko and tcpmd5.ko kernel modules.
o IPSEC_NAT_T option was removed. Now NAT-T support is enabled by
default. The UDP_ENCAP_ESPINUDP_NON_IKE encapsulation type
support was removed. Added TCP/UDP checksum handling for
inbound packets that were decapsulated by transport mode SAs.
setkey(8) modified to show run-time NAT-T configuration of SA.
o New network pseudo interface if_ipsec(4) added. For now it is
build as part of ipsec.ko module (or with IPSEC kernel).
It implements IPsec virtual tunnels to create route-based VPNs.
o The network stack now invokes IPsec functions using special
methods. The only one header file <netipsec/ipsec_support.h>
should be included to declare all the needed things to work
with IPsec.
o All IPsec protocols handlers (ESP/AH/IPCOMP protosw) were removed.
Now these protocols are handled directly via IPsec methods.
o TCP_SIGNATURE support was reworked to be more close to RFC.
o PF_KEY SADB was reworked:
- now all security associations stored in the single SPI namespace,
and all SAs MUST have unique SPI.
- several hash tables added to speed up lookups in SADB.
- SADB now uses rmlock to protect access, and concurrent threads
can do SA lookups in the same time.
- many PF_KEY message handlers were reworked to reflect changes
in SADB.
- SADB_UPDATE message was extended to support new PF_KEY headers:
SADB_X_EXT_NEW_ADDRESS_SRC and SADB_X_EXT_NEW_ADDRESS_DST. They
can be used by IKE daemon to change SA addresses.
o ipsecrequest and secpolicy structures were cardinally changed to
avoid locking protection for ipsecrequest. Now we support
only limited number (4) of bundled SAs, but they are supported
for both INET and INET6.
o INPCB security policy cache was introduced. Each PCB now caches
used security policies to avoid SP lookup for each packet.
o For inbound security policies added the mode, when the kernel does
check for full history of applied IPsec transforms.
o References counting rules for security policies and security
associations were changed. The proper SA locking added into xform
code.
o xform code was also changed. Now it is possible to unregister xforms.
tdb_xxx structures were changed and renamed to reflect changes in
SADB/SPDB, and changed rules for locking and refcounting.
Reviewed by: gnn, wblock
Obtained from: Yandex LLC
Relnotes: yes
Sponsored by: Yandex LLC
Differential Revision: https://reviews.freebsd.org/D9352
dangerous. Those wanting data from an mbuf should use DTrace itself to get
the data.
PR: 203409
Reviewed by: hiren
MFC after: 1 week
Sponsored by: Limelight Networks
Differential Revision: https://reviews.freebsd.org/D9035
When a TCP segment with the FIN bit set was received in the CLOSED state,
a TCP RST-ACK-segment is sent. When computing SEG.ACK for this, the
FIN counts as one byte. This accounting was missing and is fixed by this
patch.
Reviewed by: hiren
MFC after: 1 month
Sponsored by: Netflix, Inc.
Differential Revision: https://svn.freebsd.org/base/head
This does not cover state changes from TIME-WAIT.
Reviewed by: gnn
MFC after: 3 weeks
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D8443
either in the CLOSING or LAST-ACK state.
Reviewed by: hiren
MFC after: 3 weeks
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D8371
loss event but not use or obay the recommendations i.e. values set by it in some
cases.
Here is an attempt to solve that confusion by following relevant RFCs/drafts.
Stack only sets congestion window/slow start threshold values when there is no
CC module availalbe to take that action. All CC modules are inspected and
updated when needed to take appropriate action on loss.
tcp_stacks/fastpath module has been updated to adapt these changes.
Note: Probably, the most significant change would be to not bring congestion
window down to 1MSS on a loss signaled by 3-duplicate acks and letting
respective CC decide that value.
In collaboration with: Matt Macy <mmacy at nextbsd dot org>
Discussed on: transport@ mailing list
Reviewed by: jtl
MFC after: 1 month
Sponsored by: Limelight Networks
Differential Revision: https://reviews.freebsd.org/D8225
after having been dropped.
This fixes enforces in_pcbdrop() logic in tcp_input():
"in_pcbdrop() is used by TCP to mark an inpcb as unused and avoid future packet
delivery or event notification when a socket remains open but TCP has closed."
PR: 203175
Reported by: Palle Girgensohn, Slawa Olhovchenkov
Tested by: Slawa Olhovchenkov
Reviewed by: Slawa Olhovchenkov
Approved by: gnn, Slawa Olhovchenkov
Differential Revision: https://reviews.freebsd.org/D8211
MFC after: 1 week
Sponsored by: Verisign, inc
to at least 64.
This is still just a coverup to avoid kernel panic and not an actual fix.
PR: 213232
Reviewed by: glebius
MFC after: 1 week
Sponsored by: Limelight Networks
Differential Revision: https://reviews.freebsd.org/D8272
Also renamed some tfo labels and added/reworked comments for clarity.
Based on an initial patch from jtl.
PR: 213424
Reviewed by: jtl
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D8235
received on a TCP session that has entered the ESTABLISHED state. This
results in a lot of calls to reset the keepalive timer.
This patch changes the behavior so we set the keepalive timer for the
keepalive idle time (TP_KEEPIDLE). When the keepalive timer fires, it will
first check to see if the session has been idle for TP_KEEPIDLE ticks. If
not, it will reschedule the keepalive timer for the time the session will
have been idle for TP_KEEPIDLE ticks.
For a session with regular communication, the keepalive timer should fire
approximately once every TP_KEEPIDLE ticks. For sessions with irregular
communication, the keepalive timer might fire more often. But, the
disruption from a periodic keepalive timer should be less than the regular
cost of resetting the keepalive timer on every packet.
(FWIW, this change saved approximately 1.73% of the busy CPU cycles on a
particular test system with a heavy TCP output load. Of course, the
actual impact is very specific to the particular hardware and workload.)
Reviewed by: gallatin, rrs
MFC after: 2 weeks
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D8243
the TCP_RFC7413 kernel option. This change removes those few instructions
from the packet processing path.
While not strictly necessary, for the sake of consistency, I applied the
new IS_FASTOPEN macro to all places in the packet processing path that
used the (t_flags & TF_FASTOPEN) check.
Reviewed by: hiren
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D8219
TCPCB, it checks (so->so_options & SO_ACCEPTCONN) to determine whether or
not the socket is a listening socket. However, this causes the code to
access a different cacheline. If we first check if the socket is in the
LISTEN state, we can avoid accessing so->so_options when processing packets
received for ESTABLISHED sessions.
If INVARIANTS is defined, the code still needs to access both variables to
check that so->so_options is consistent with the state.
Reviewed by: gallatin
MFC after: 1 week
Sponsored by: Netflix
to add actions that run when a TCP frame is sent or received on a TCP
session in the ESTABLISHED state. In the base tree, this functionality is
only used for the h_ertt module, which is used by the cc_cdg, cc_chd, cc_hd,
and cc_vegas congestion control modules.
Presently, we incur overhead to check for hooks each time a TCP frame is
sent or received on an ESTABLISHED TCP session.
This change adds a new compile-time option (TCP_HHOOK) to determine whether
to include the hhook(9) framework for TCP. To retain backwards
compatibility, I added the TCP_HHOOK option to every configuration file that
already defined "options INET". (Therefore, this patch introduces no
functional change. In order to see a functional difference, you need to
compile a custom kernel without the TCP_HHOOK option.) This change will
allow users to easily exclude this functionality from their kernel, should
they wish to do so.
Note that any users who use a custom kernel configuration and use one of the
congestion control modules listed above will need to add the TCP_HHOOK
option to their kernel configuration.
Reviewed by: rrs, lstewart, hiren (previous version), sjg (makefiles only)
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D8185
Restructure code slightly to save ip_tos bits earlier. Fix the bug
where the ip_tos field is zeroed out before assigning to the iptos
variable. Restore the ip_tos and ip_ver fields only if they have
been zeroed during the pseudo-header checksum calculation.
Reviewed by: cem, gnn, hiren
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D8053
tso_segsz pkthdr field during RX processing, and use the information in TCP for
more correct accounting and as a congestion control input. This is only a start,
and an audit of other uses for the data is left as future work.
Reviewed by: gallatin, rrs
Sponsored by: Netflix, Inc.
Differential Revision: https://reviews.freebsd.org/D7564
control to a three way setting.
0 - Totally disable ECN. (no change)
1 - Enable ECN if incoming connections request it. Outgoing
connections will request ECN. (no change from present != 0 setting)
2 - Enable ECN if incoming connections request it. Outgoing
conections will not request ECN.
Change the default value of net.inet.tcp.ecn.enable from 0 to 2.
Linux version 2.4.20 and newer, Solaris, and Mac OS X 10.5 and newer have
similar capabilities. The actual values above match Linux, and the default
matches the current Linux default.
Reviewed by: eadler
MFC after: 1 month
MFH: yes
Sponsored by: https://reviews.freebsd.org/D6386
tp->snd_wnd. This can happen, for example, when the remote side responds to
a window probe by ACKing the one byte it contains.
Differential Revision: https://reviews.freebsd.org/D5625
Reviewed by: hiren
Obtained from: Juniper Networks (earlier version)
MFC after: 2 weeks
Sponsored by: Juniper Networks
struct tcpstat, because the structure can be zeroed out by netstat(1) -z,
and of course running connection counts shouldn't be touched.
Place running connection counts into separate array, and provide
separate read-only sysctl oid for it.
and t_maxseg. This dualism emerged with T/TCP, but was not properly cleaned
up after T/TCP removal. After all permutations over the years the result is
that t_maxopd stores a minimum of peer offered MSS and MTU reduced by minimum
protocol header. And t_maxseg stores (t_maxopd - TCPOLEN_TSTAMP_APPA) if
timestamps are in action, or is equal to t_maxopd otherwise. That's a very
rough estimate of MSS reduced by options length. Throughout the code it
was used in places, where preciseness was not important, like cwnd or
ssthresh calculations.
With this change:
- t_maxopd goes away.
- t_maxseg now stores MSS not adjusted by options.
- new function tcp_maxseg() is provided, that calculates MSS reduced by
options length. The functions gives a better estimate, since it takes
into account SACK state as well.
Reviewed by: jtl
Differential Revision: https://reviews.freebsd.org/D3593
TFO is disabled by default in the kernel build. See the top comment
in sys/netinet/tcp_fastopen.c for implementation particulars.
Reviewed by: gnn, jch, stas
MFC after: 3 days
Sponsored by: Verisign, Inc.
Differential Revision: https://reviews.freebsd.org/D4350
to do is to clean up the timer handling using the async-drain.
Other optimizations may be coming to go with this. Whats here
will allow differnet tcp implementations (one included).
Reviewed by: jtl, hiren, transports
Sponsored by: Netflix Inc.
Differential Revision: D4055
other end till it reaches predetermined threshold which is 3 for us right now.
Once that happens, we trigger fast-retransmit to do loss recovery.
Main problem with the current implementation is that we don't honor SACK
information well to detect whether an incoming ack is a dupack or not. RFC6675
has latest recommendations for that. According to it, dupack is a segment that
arrives carrying a SACK block that identifies previously unknown information
between snd_una and snd_max even if it carries new data, changes the advertised
window, or moves the cumulative acknowledgment point.
With the prevalence of Selective ACK (SACK) these days, improper handling can
lead to delayed loss recovery.
With the fix, new behavior looks like following:
0) th_ack < snd_una --> ignore
Old acks are ignored.
1) th_ack == snd_una, !sack_changed --> ignore
Acks with SACK enabled but without any new SACK info in them are ignored.
2) th_ack == snd_una, window == old_window --> increment
Increment on a good dupack.
3) th_ack == snd_una, window != old_window, sack_changed --> increment
When SACK enabled, it's okay to have advertized window changed if the ack has
new SACK info.
4) th_ack > snd_una --> reset to 0
Reset to 0 when left edge moves.
5) th_ack > snd_una, sack_changed --> increment
Increment if left edge moves but there is new SACK info.
Here, sack_changed is the indicator that incoming ack has previously unknown
SACK info in it.
Note: This fix is not fully compliant to RFC6675. That may require a few
changes to current implementation in order to keep per-sackhole dupack counter
and change to the way we mark/handle sack holes.
PR: 203663
Reviewed by: jtl
MFC after: 3 weeks
Sponsored by: Limelight Networks
Differential Revision: https://reviews.freebsd.org/D4225
suggested by RFC 6675.
Currently differnt places in the stack tries to guess this in suboptimal ways.
The main problem is that current calculations don't take sacked bytes into
account. Sacked bytes are the bytes receiver acked via SACK option. This is
suboptimal because it assumes that network has more outstanding (unacked) bytes
than the actual value and thus sends less data by setting congestion window
lower than what's possible which in turn may cause slower recovery from losses.
As an example, one of the current calculations looks something like this:
snd_nxt - snd_fack + sackhint.sack_bytes_rexmit
New proposal from RFC 6675 is:
snd_max - snd_una - sackhint.sacked_bytes + sackhint.sack_bytes_rexmit
which takes sacked bytes into account which is a new addition to the sackhint
struct. Only thing we are missing from RFC 6675 is isLost() i.e. segment being
considered lost and thus adjusting pipe based on that which makes this
calculation a bit on conservative side.
The approach is very simple. We already process each ack with sack info in
tcp_sack_doack() and extract sack blocks/holes out of it. We'd now also track
this new variable sacked_bytes which keeps track of total sacked bytes reported.
One downside to this approach is that we may get incorrect count of sacked_bytes
if the other end decides to drop sack info in the ack because of memory pressure
or some other reasons. But in this (not very likely) case also the pipe
calculation would be conservative which is okay as opposed to being aggressive
in sending packets into the network.
Next step is to use this more accurate pipe estimation to drive congestion
window adjustments.
In collaboration with: rrs
Reviewed by: jason_eggnet dot com, rrs
MFC after: 2 weeks
Sponsored by: Limelight Networks
Differential Revision: https://reviews.freebsd.org/D3971
window in number of segments on fly. It is set to 10 segments by default.
Remove net.inet.tcp.experimental.initcwnd10 which is now redundant. Also remove
the parent node net.inet.tcp.experimental as it's not needed anymore and also
because it was not well thought out.
Differential Revision: https://reviews.freebsd.org/D3858
In collaboration with: lstewart
Reviewed by: gnn (prev version), rwatson, allanjude, wblock (man page)
MFC after: 2 weeks
Relnotes: yes
Sponsored by: Limelight Networks
packets and/or state transitions from each TCP socket. That would help with
narrowing down certain problems we see in the field that are hard to reproduce
without understanding the history of how we got into a certain state. This
change provides just that.
It saves copies of the last N packets in a list in the tcpcb. When the tcpcb is
destroyed, the list is freed. I thought this was likely to be more
performance-friendly than saving copies of the tcpcb. Plus, with the packets,
you should be able to reverse-engineer what happened to the tcpcb.
To enable the feature, you will need to compile a kernel with the TCPPCAP
option. Even then, the feature defaults to being deactivated. You can activate
it by setting a positive value for the number of captured packets. You can do
that on either a global basis or on a per-socket basis (via a setsockopt call).
There is no way to get the packets out of the kernel other than using kmem or
getting a coredump. I thought that would help some of the legal/privacy concerns
regarding such a feature. However, it should be possible to add a future effort
to export them in PCAP format.
I tested this at low scale, and found that there were no mbuf leaks and the peak
mbuf usage appeared to be unchanged with and without the feature.
The main performance concern I can envision is the number of mbufs that would be
used on systems with a large number of sockets. If you save five packets per
direction per socket and have 3,000 sockets, that will consume at least 30,000
mbufs just to keep these packets. I tried to reduce the concerns associated with
this by limiting the number of clusters (not mbufs) that could be used for this
feature. Again, in my testing, that appears to work correctly.
Differential Revision: D3100
Submitted by: Jonathan Looney <jlooney at juniper dot net>
Reviewed by: gnn, hiren
Initially function was introduced in r53541 (KAME initial commit) to
"provide hints from upper layer protocols that indicate a connection
is making "forward progress"" (quote from RFC 2461 7.3.1 Reachability
Confirmation).
However, it was converted to do nothing (e.g. just return) in r122922
(tcp_hostcache implementation) back in 2003. Some defines were moved
to tcp_var.h in r169541. Then, it was broken (for non-corner cases)
by r186119 (L2<>L3 split) in 2008 (NULL ifp in nd6_lookup). So,
right now this code is broken and has no "real" base users.
Differential Revision: https://reviews.freebsd.org/D3699
to provide the TCPDEBUG functionality with pure DTrace.
Reviewed by: rwatson
MFC after: 2 weeks
Sponsored by: Limelight Networks
Differential Revision: D3530
- The existing TCP INP_INFO lock continues to protect the global inpcb list
stability during full list traversal (e.g. tcp_pcblist()).
- A new INP_LIST lock protects inpcb list actual modifications (inp allocation
and free) and inpcb global counters.
It allows to use TCP INP_INFO_RLOCK lock in critical paths (e.g. tcp_input())
and INP_INFO_WLOCK only in occasional operations that walk all connections.
PR: 183659
Differential Revision: https://reviews.freebsd.org/D2599
Reviewed by: jhb, adrian
Tested by: adrian, nitroboost-gmail.com
Sponsored by: Verisign, Inc.
non-inline urgent data and introduce an mbuf exhaustion attack vector
similar to FreeBSD-SA-15:15.tcp, but not requiring VNETs.
Address the issue described in FreeBSD-SA-15:15.tcp.
Reviewed by: glebius
Approved by: so
Approved by: jmallett (mentor)
Security: FreeBSD-SA-15:15.tcp
Sponsored by: Norse Corp, Inc.
scaling code does not use an uninitialized timestamp echo reply value
from the stack when timestamps are not enabled.
Differential Revision: https://reviews.freebsd.org/D3060
Reviewed by: hiren
Approved by: jmallett (mentor)
MFC after: 3 days
Sponsored by: Norse Corp, Inc.
