Normally the socket buffers are static (either derived from global
defaults or set with setsockopt) and do not adapt to real network
conditions. Two things happen: a) your socket buffers are too small
and you can't reach the full potential of the network between both
hosts; b) your socket buffers are too big and you waste a lot of
kernel memory for data just sitting around.
With automatic TCP send and receive socket buffers we can start with a
small buffer and quickly grow it in parallel with the TCP congestion
window to match real network conditions.
FreeBSD has a default 32K send socket buffer. This supports a maximal
transfer rate of only slightly more than 2Mbit/s on a 100ms RTT
trans-continental link. Or at 200ms just above 1Mbit/s. With TCP send
buffer auto scaling and the default values below it supports 20Mbit/s
at 100ms and 10Mbit/s at 200ms. That's an improvement of factor 10, or
1000%. For the receive side it looks slightly better with a default of
64K buffer size.
New sysctls are:
net.inet.tcp.sendbuf_auto=1 (enabled)
net.inet.tcp.sendbuf_inc=8192 (8K, step size)
net.inet.tcp.sendbuf_max=262144 (256K, growth limit)
net.inet.tcp.recvbuf_auto=1 (enabled)
net.inet.tcp.recvbuf_inc=16384 (16K, step size)
net.inet.tcp.recvbuf_max=262144 (256K, growth limit)
Tested by: many (on HEAD and RELENG_6)
Approved by: re
MFC after: 1 month
In ip6_sprintf no longer use and return one of eight static buffers
for printing/logging ipv6 addresses.
The caller now has to hand in a sufficiently large buffer as first
argument.
begun with a repo-copy of mac.h to mac_framework.h. sys/mac.h now
contains the userspace and user<->kernel API and definitions, with all
in-kernel interfaces moved to mac_framework.h, which is now included
across most of the kernel instead.
This change is the first step in a larger cleanup and sweep of MAC
Framework interfaces in the kernel, and will not be MFC'd.
Obtained from: TrustedBSD Project
Sponsored by: SPARTA
the header field for possible later IPSEC SPD lookup, even
when the kernel is built without 'options INET6'.
PR: kern/57760
MFC after: 1 week
Submitted by: Joachim Schueth
functionality:
- Remove a rwlock aquisition/release per generated syncookie. Locking
is now integrated with the bucket row locking of syncache itself and
syncookies no longer add any additional lock overhead.
- Syncookie secrets are different for and stored per syncache buck row.
Secrets expire after 16 seconds and are reseeded on-demand.
- The computational overhead for syncookie generation and verification
is one MD5 hash computation as before.
- Syncache can be turned off and run with syncookies only by setting the
sysctl net.inet.tcp.syncookies_only=1.
This implementation extends the orginal idea and first implementation
of FreeBSD by using not only the initial sequence number field to store
information but also the timestamp field if present. This way we can
keep track of the entire state we need to know to recreate the session in
its original form. Almost all TCP speakers implement RFC1323 timestamps
these days. For those that do not we still have to live with the known
shortcomings of the ISN only SYN cookies. The use of the timestamp field
causes the timestamps to be randomized if syncookies are enabled.
The idea of SYN cookies is to encode and include all necessary information
about the connection setup state within the SYN-ACK we send back and thus
to get along without keeping any local state until the ACK to the SYN-ACK
arrives (if ever). Everything we need to know should be available from
the information we encoded in the SYN-ACK.
A detailed description of the inner working of the syncookies mechanism
is included in the comments in tcp_syncache.c.
Reviewed by: silby (slightly earlier version)
Sponsored by: TCP/IP Optimization Fundraise 2005
timeouts for TCP and T/TCP connections in the TIME_WAIT
state, and we had two separate timed wait queues for them.
Now that is has gone, the timeout is always 2*MSL again,
and there is no reason to keep two queues (the first was
unused anyway!).
Also, reimplement the remaining queue using a TAILQ (it
was technically impossible before, with two queues).
o add IFCAP_TSO[46] for drivers to announce this capability for IPv4 and IPv6
o add CSUM_TSO flag to mbuf pkthdr csum_flags field
o add tso_segsz field to mbuf pkthdr
o enhance ip_output() packet length check to allow for large TSO packets
o extend tcp_maxmtu[46]() with a flag pointer to pass interface capabilities
o adjust all callers of tcp_maxmtu[46]() accordingly
Discussed on: -current, -net
Sponsored by: TCP/IP Optimization Fundraise 2005
o don't assign remote/local host/port information manually between provided
struct in_conninfo and struct syncache, bcopy() it instead
o rename sc_tsrecent to sc_tsreflect in struct syncache to better capture
the purpose of this field
o rename sc_request_r_scale to sc_requested_r_scale for ditto reasons
o fix IPSEC error case printf's to report correct function name
o in syncache_socket() only transpose enhanced tcp options parameters to
struct tcpcb when the inpcb doesn't has TF_NOOPT set
o in syncache_respond() reorder stack variables
o in syncache_respond() remove bogus KASSERT()
No functional changes.
Sponsored by: TCP/IP Optimization Fundraise 2005
o redefine the parameter 'is_syn' to 'flags', add TO_SYN flag and adjust its
usage accordingly
o update the comments to the tcp_dooptions() invocation in
tcp_input():after_listen to reflect reality
o move the logic checking the echoed timestamp out of tcp_dooptions() to the
only place that uses it next to the invocation described in the previous
item
o adjust parsing of TCPOPT_SACK_PERMITTED to use the same style as the others
o add comments in to struct tcpopt.to_flags #defines
No functional changes.
Sponsored by: TCP/IP Optimization Fundraise 2005
ACK the SYN as required by RFC793, rather than ignoring it. NetBSD
have had a similar change since 1999.
PR: 93236
Submitted by: Grant Edwards <grante@visi.com>
MFC after: 1 month
as possible for the syncache_add() case. The syncache timer no longer
aquires the tcpinfo lock and timeout/retransmit runs can happen in
parallel with bucket granularity.
On a P4 the additional locks cause a slight degression of 0.7% in tcp
connections per second. When IP and TCP input are deserialized and
can run in parallel this little overhead can be neglected. The syncookie
handling still leaves room for improvement and its random salts may be
moved to the syncache bucket head structures to remove the second lock
operation currently required for it. However this would be a more
involved change from the way syncookies work at the moment.
Reviewed by: rwatson
Tested by: rwatson, ps (earlier version)
Sponsored by: TCP/IP Optimization Fundraise 2005
reference. For now, we allow the possibility that the in_ppcb
pointer in the inpcb may be NULL if a timewait socket has had its
tcptw structure recycled. This allows tcp_timewait() to
consistently unlock the inpcb.
Reported by: Kazuaki Oda <kaakun at highway dot ne dot jp>
MFC after: 3 months
tcp_timewait(). This corrects a bug (or lack of fixing of a bug)
in tcp_input.c:1.295.
Submitted by: Kazuaki Oda <kaakun at highway dot ne dot jp>
MFC after: 3 months
NULL. We currently do allow this to happen, but may want to remove that
possibility in the future. This case can occur when a socket is left
open after TCP wraps up, and the timewait state is recycled. This will
be cleaned up in the future.
Found by: Kazuaki Oda <kaakun at highway dot ne dot jp>
MFC after: 3 months
casts.
Consistently use intotw() to cast inp_ppcb pointers to struct tcptw *
pointers.
Consistently use intotcpcb() to cast inp_ppcb pointers to struct tcpcb *
pointers.
Don't assign tp to the results to intotcpcb() during variable declation
at the top of functions, as that is before the asserts relating to
locking have been performed. Do this later in the function after
appropriate assertions have run to allow that operation to be conisdered
safe.
MFC after: 3 months
pru_abort(), pru_detach(), and in_pcbdetach():
- Universally support and enforce the invariant that so_pcb is
never NULL, converting dozens of unnecessary NULL checks into
assertions, and eliminating dozens of unnecessary error handling
cases in protocol code.
- In some cases, eliminate unnecessary pcbinfo locking, as it is no
longer required to ensure so_pcb != NULL. For example, the receive
code no longer requires the pcbinfo lock, and the send code only
requires it if building a new connection on an otherwise unconnected
socket triggered via sendto() with an address. This should
significnatly reduce tcbinfo lock contention in the receive and send
cases.
- In order to support the invariant that so_pcb != NULL, it is now
necessary for the TCP code to not discard the tcpcb any time a
connection is dropped, but instead leave the tcpcb until the socket
is shutdown. This case is handled by setting INP_DROPPED, to
substitute for using a NULL so_pcb to indicate that the connection
has been dropped. This requires the inpcb lock, but not the pcbinfo
lock.
- Unlike all other protocols in the tree, TCP may need to retain access
to the socket after the file descriptor has been closed. Set
SS_PROTOREF in tcp_detach() in order to prevent the socket from being
freed, and add a flag, INP_SOCKREF, so that the TCP code knows whether
or not it needs to free the socket when the connection finally does
close. The typical case where this occurs is if close() is called on
a TCP socket before all sent data in the send socket buffer has been
transmitted or acknowledged. If INP_SOCKREF is found when the
connection is dropped, we release the inpcb, tcpcb, and socket instead
of flagging INP_DROPPED.
- Abort and detach protocol switch methods no longer return failures,
nor attempt to free sockets, as the socket layer does this.
- Annotate the existence of a long-standing race in the TCP timer code,
in which timers are stopped but not drained when the socket is freed,
as waiting for drain may lead to deadlocks, or have to occur in a
context where waiting is not permitted. This race has been handled
by testing to see if the tcpcb pointer in the inpcb is NULL (and vice
versa), which is not normally permitted, but may be true of a inpcb
and tcpcb have been freed. Add a counter to test how often this race
has actually occurred, and a large comment for each instance where
we compare potentially freed memory with NULL. This will have to be
fixed in the near future, but requires is to further address how to
handle the timer shutdown shutdown issue.
- Several TCP calls no longer potentially free the passed inpcb/tcpcb,
so no longer need to return a pointer to indicate whether the argument
passed in is still valid.
- Un-macroize debugging and locking setup for various protocol switch
methods for TCP, as it lead to more obscurity, and as locking becomes
more customized to the methods, offers less benefit.
- Assert copyright on tcp_usrreq.c due to significant modifications that
have been made as part of this work.
These changes significantly modify the memory management and connection
logic of our TCP implementation, and are (as such) High Risk Changes,
and likely to contain serious bugs. Please report problems to the
current@ mailing list ASAP, ideally with simple test cases, and
optionally, packet traces.
MFC after: 3 months
right from the beginning and partly clean up the differences in handling
between SYN_SENT and SYN_RCVD (syncache).
Further changes to this code to come. This is a first incremental step
to a general overhaul and streamlining of the TCP code.
PR: kern/15095
PR: kern/92690 (partly)
Reviewed by: qingli (and tested with ANVL)
Sponsored by: TCP/IP Optimization Fundraise 2005
simultaneous open. Both the bug and the patch were verified using the
ANVL test suite.
PR: kern/74935
Submitted by: qingli (before I became committer)
Reviewed by: andre
MFC after: 5 days
threshold. Inflight doesn't make sense on a LAN as it has
trouble figuring out the maximal bandwidth because of the coarse
tick granularity.
The sysctl net.inet.tcp.inflight.rttthresh specifies the threshold
in milliseconds below which inflight will disengage. It defaults
to 10ms.
Tested by: Joao Barros <joao.barros-at-gmail.com>,
Rich Murphey <rich-at-whiteoaklabs.com>
Sponsored by: TCP/IP Optimization Fundraise 2005
This fixes a bug in the previous commit.
Found by: Coverity Prevent(tm)
Coverity ID: CID253
Sponsored by: TCP/IP Optimization Fundraise 2005
MFC after: 3 days
include ip_options.h into all files making use of IP Options functions.
From ip_input.c rev 1.306:
ip_dooptions(struct mbuf *m, int pass)
save_rte(m, option, dst)
ip_srcroute(m0)
ip_stripoptions(m, mopt)
From ip_output.c rev 1.249:
ip_insertoptions(m, opt, phlen)
ip_optcopy(ip, jp)
ip_pcbopts(struct inpcb *inp, int optname, struct mbuf *m)
No functional changes in this commit.
Discussed with: rwatson
Sponsored by: TCP/IP Optimization Fundraise 2005
between sack and a bug in the "bad retransmit recovery" logic. This is
a workaround, the underlying bug will be fixed later.
Submitted by: Mohan Srinivasan, Noritoshi Demizu
TTL a packet must have when received on a socket. All packets with a
lower TTL are silently dropped. Works on already connected/connecting
and listening sockets for RAW/UDP/TCP.
This option is only really useful when set to 255 preventing packets
from outside the directly connected networks reaching local listeners
on sockets.
Allows userland implementation of 'The Generalized TTL Security Mechanism
(GTSM)' according to RFC3682. Examples of such use include the Cisco IOS
BGP implementation command "neighbor ttl-security".
MFC after: 2 weeks
Sponsored by: TCP/IP Optimization Fundraise 2005
after PAWS checks. The symptom of this is an inconsistency in the cached
sack state, caused by the fact that the sack scoreboard was not being
updated for an ACK handled in the header prediction path.
Found by: Andrey Chernov.
Submitted by: Noritoshi Demizu, Raja Mukerji.
Approved by: re
does not clear tlen and frees the mbuf (leaving th pointing at
freed memory), if the data segment is a complete duplicate.
This change works around that bug. A fix for the tcp_reass() bug
will appear later (that bug is benign for now, as neither th nor
tlen is referenced in tcp_input() after the call to tcp_reass()).
Found by: Pawel Jakub Dawidek.
Submitted by: Raja Mukerji, Noritoshi Demizu.
Approved by: re
The ipfw tables lookup code caches the result of the last query. The
kernel may process multiple packets concurrently, performing several
concurrent table lookups. Due to an insufficient locking, a cached
result can become corrupted that could cause some addresses to be
incorrectly matched against a lookup table.
Submitted by: ru
Reviewed by: csjp, mlaier
Security: CAN-2005-2019
Security: FreeBSD-SA-05:13.ipfw
Correct bzip2 permission race condition vulnerability.
Obtained from: Steve Grubb via RedHat
Security: CAN-2005-0953
Security: FreeBSD-SA-05:14.bzip2
Approved by: obrien
Correct TCP connection stall denial of service vulnerability.
A TCP packets with the SYN flag set is accepted for established
connections, allowing an attacker to overwrite certain TCP options.
Submitted by: Noritoshi Demizu
Reviewed by: andre, Mohan Srinivasan
Security: CAN-2005-2068
Security: FreeBSD-SA-05:15.tcp
Approved by: re (security blanket), cperciva
processing is now done in the ACK processing case.
- Merge tcp_sack_option() and tcp_del_sackholes() into a new function
called tcp_sack_doack().
- Test (SEG.ACK < SND.MAX) before processing the ACK.
Submitted by: Noritoshi Demizu
Reveiewed by: Mohan Srinivasan, Raja Mukerji
Approved by: re
or to compute the total retransmitted bytes in this sack recovery
episode, the scoreboard is traversed. While in sack recovery, this
traversal occurs on every call to tcp_output(), every dupack and
every partial ack. The scoreboard could potentially get quite large,
making this traversal expensive.
This change optimizes this by storing hints (for the next hole to
retransmit and the total retransmitted bytes in this sack recovery
episode) reducing the complexity to find these values from O(n) to
constant time.
The debug code that sanity checks the hints against the computed
value will be removed eventually.
Submitted by: Mohan Srinivasan, Noritoshi Demizu, Raja Mukerji.
in flight in SACK recovery.
Found by: Noritoshi Demizu
Submitted by: Mohan Srinivasan <mohans at yahoo-inc dot com>
Noritoshi Demizu <demizu at dd dot ij4u dot or dot jp>
Raja Mukerji <raja at moselle dot com>
setting ts_recent to an arbitrary value, stopping further
communication between the two hosts.
- If the Echoed Timestamp is greater than the current time,
fall back to the non RFC 1323 RTT calculation.
Submitted by: Raja Mukerji (raja at moselle dot com)
Reviewed by: Noritoshi Demizu, Mohan Srinivasan
a reassembly queue state structure, don't update (receiver) sack
report.
- Similarly, if tcp_drain() is called, freeing up all items on the
reassembly queue, clean the sack report.
Found, Submitted by: Noritoshi Demizu <demizu at dd dot iij4u dot or dot jp>
Reviewed by: Mohan Srinivasan (mohans at yahoo-inc dot com),
Raja Mukerji (raja at moselle dot com).
reported to the sender - in the case where the sender sends data
outside the window (as WinXP does :().
Reported by: Sam Jensen <sam at wand dot net dot nz>
Submitted by: Mohan Srinivasan
Remove the SACK "initburst" sysctl.
- Fix bugs in SACK dupack and partialack handling that can cause
large bursts while in SACK recovery.
Submitted by: Mohan Srinivasan
that the RFC 793 specification for accepting RST packets should be
following. When followed, this makes one vulnerable to the attacks
described in "slipping in the window", but it may be necessary in
some odd circumstances.
cases for tcp_input():
While it is true that the pcbinfo lock provides a pseudo-reference to
inpcbs, both the inpcb and pcbinfo locks are required to free an
un-referenced inpcb. As such, we can release the pcbinfo lock as
long as the inpcb remains locked with the confidence that it will not
be garbage-collected. This leads to a less conservative locking
strategy that should reduce contention on the TCP pcbinfo lock.
Discussed with: sam
pointer updates: test available space while holding the socket buffer
mutex, and continue to hold until until the pointer update has been
performed.
MFC after: 2 weeks
window was 0 bytes in size. This may have been the cause of unsolved
"connection not closing" reports over the years.
Thanks to Michiel Boland for providing the fix and providing a concise
test program for the problem.
Submitted by: Michiel Boland
MFC after: 2 weeks
contents of the tcpcb are read and modified in volume.
In tcp_input(), replace th comparison with 0 with a comparison with
NULL.
At the 'findpcb', 'dropafterack', and 'dropwithreset' labels in
tcp_input(), assert 'headlocked'. Try to improve consistency between
various assertions regarding headlocked to be more informative.
MFC after: 2 weeks
structure, so assert the inpcb lock associated with the tcptw.
Also assert the tcbinfo lock, as tcp_timewait() may call
tcp_twclose() or tcp_2msl_rest(), which require it. Since
tcp_timewait() is already called with that lock from tcp_input(),
this doesn't change current locking, merely documents reasons for
it.
In tcp_twstart(), assert the tcbinfo lock, as tcp_timer_2msl_rest()
is called, which requires that lock.
In tcp_twclose(), assert the tcbinfo lock, as tcp_timer_2msl_stop()
is called, which requires that lock.
Document the locking strategy for the time wait queues in tcp_timer.c,
which consists of protecting the time wait queues in the same manner
as the tcbinfo structure (using the tcbinfo lock).
In tcp_timer_2msl_reset(), assert the tcbinfo lock, as the time wait
queues are modified.
In tcp_timer_2msl_stop(), assert the tcbinfo lock, as the time wait
queues may be modified.
In tcp_timer_2msl_tw(), assert the tcbinfo lock, as the time wait
queues may be modified.
MFC after: 2 weeks
retain the pcbinfo lock until we're done using a pcb in the in-bound
path, as the pcbinfo lock acts as a pseuo-reference to prevent the pcb
from potentially being recycled. Clean up assertions and make sure to
assert that the pcbinfo is locked at the head of code subsections where
it is needed. Free the mbuf at the end of tcp_input after releasing
any held locks to reduce the time the locks are held.
MFC after: 3 weeks
A complete rationale and discussion is given in this message
and the resulting discussion:
http://docs.freebsd.org/cgi/mid.cgi?4177C8AD.6060706
Note that this commit removes only the functional part of T/TCP
from the tcp_* related functions in the kernel. Other features
introduced with RFC1644 are left intact (socket layer changes,
sendmsg(2) on connection oriented protocols) and are meant to
be reused by a simpler and less intrusive reimplemention of the
previous T/TCP functionality.
Discussed on: -arch
to control the packets injected while in sack recovery (for both
retransmissions and new data).
- Cleanups to the sack codepaths in tcp_output.c and tcp_sack.c.
- Add a new sysctl (net.inet.tcp.sack.initburst) that controls the
number of sack retransmissions done upon initiation of sack recovery.
Submitted by: Mohan Srinivasan <mohans@yahoo-inc.com>
and preserves the ipfw ABI. The ipfw core packet inspection and filtering
functions have not been changed, only how ipfw is invoked is different.
However there are many changes how ipfw is and its add-on's are handled:
In general ipfw is now called through the PFIL_HOOKS and most associated
magic, that was in ip_input() or ip_output() previously, is now done in
ipfw_check_[in|out]() in the ipfw PFIL handler.
IPDIVERT is entirely handled within the ipfw PFIL handlers. A packet to
be diverted is checked if it is fragmented, if yes, ip_reass() gets in for
reassembly. If not, or all fragments arrived and the packet is complete,
divert_packet is called directly. For 'tee' no reassembly attempt is made
and a copy of the packet is sent to the divert socket unmodified. The
original packet continues its way through ip_input/output().
ipfw 'forward' is done via m_tag's. The ipfw PFIL handlers tag the packet
with the new destination sockaddr_in. A check if the new destination is a
local IP address is made and the m_flags are set appropriately. ip_input()
and ip_output() have some more work to do here. For ip_input() the m_flags
are checked and a packet for us is directly sent to the 'ours' section for
further processing. Destination changes on the input path are only tagged
and the 'srcrt' flag to ip_forward() is set to disable destination checks
and ICMP replies at this stage. The tag is going to be handled on output.
ip_output() again checks for m_flags and the 'ours' tag. If found, the
packet will be dropped back to the IP netisr where it is going to be picked
up by ip_input() again and the directly sent to the 'ours' section. When
only the destination changes, the route's 'dst' is overwritten with the
new destination from the forward m_tag. Then it jumps back at the route
lookup again and skips the firewall check because it has been marked with
M_SKIP_FIREWALL. ipfw 'forward' has to be compiled into the kernel with
'option IPFIREWALL_FORWARD' to enable it.
DUMMYNET is entirely handled within the ipfw PFIL handlers. A packet for
a dummynet pipe or queue is directly sent to dummynet_io(). Dummynet will
then inject it back into ip_input/ip_output() after it has served its time.
Dummynet packets are tagged and will continue from the next rule when they
hit the ipfw PFIL handlers again after re-injection.
BRIDGING and IPFW_ETHER are not changed yet and use ipfw_chk() directly as
they did before. Later this will be changed to dedicated ETHER PFIL_HOOKS.
More detailed changes to the code:
conf/files
Add netinet/ip_fw_pfil.c.
conf/options
Add IPFIREWALL_FORWARD option.
modules/ipfw/Makefile
Add ip_fw_pfil.c.
net/bridge.c
Disable PFIL_HOOKS if ipfw for bridging is active. Bridging ipfw
is still directly invoked to handle layer2 headers and packets would
get a double ipfw when run through PFIL_HOOKS as well.
netinet/ip_divert.c
Removed divert_clone() function. It is no longer used.
netinet/ip_dummynet.[ch]
Neither the route 'ro' nor the destination 'dst' need to be stored
while in dummynet transit. Structure members and associated macros
are removed.
netinet/ip_fastfwd.c
Removed all direct ipfw handling code and replace it with the new
'ipfw forward' handling code.
netinet/ip_fw.h
Removed 'ro' and 'dst' from struct ip_fw_args.
netinet/ip_fw2.c
(Re)moved some global variables and the module handling.
netinet/ip_fw_pfil.c
New file containing the ipfw PFIL handlers and module initialization.
netinet/ip_input.c
Removed all direct ipfw handling code and replace it with the new
'ipfw forward' handling code. ip_forward() does not longer require
the 'next_hop' struct sockaddr_in argument. Disable early checks
if 'srcrt' is set.
netinet/ip_output.c
Removed all direct ipfw handling code and replace it with the new
'ipfw forward' handling code.
netinet/ip_var.h
Add ip_reass() as general function. (Used from ipfw PFIL handlers
for IPDIVERT.)
netinet/raw_ip.c
Directly check if ipfw and dummynet control pointers are active.
netinet/tcp_input.c
Rework the 'ipfw forward' to local code to work with the new way of
forward tags.
netinet/tcp_sack.c
Remove include 'opt_ipfw.h' which is not needed here.
sys/mbuf.h
Remove m_claim_next() macro which was exclusively for ipfw 'forward'
and is no longer needed.
Approved by: re (scottl)
- Trailing tab/space cleanup
- Remove spurious spaces between or before tabs
This change avoids touching files that Andre likely has in his working
set for PFIL hooks changes for IPFW/DUMMYNET.
Approved by: re (scottl)
Submitted by: Xin LI <delphij@frontfree.net>
Fix this problem by separating out the SACK and the newreno cases. Also, check
if we are in FASTRECOVERY for the sack case and if so, turn off dupacks.
Fix an issue where the congestion window was not being incremented by ssthresh.
Thanks to Mohan Srinivasan for finding this problem.
associated with performing a wakeup on the socket buffer:
- When performing an sbappend*() followed by a so[rw]wakeup(), explicitly
acquire the socket buffer lock and use the _locked() variants of both
calls. Note that the _locked() sowakeup() versions unlock the mutex on
return. This is done in uipc_send(), divert_packet(), mroute
socket_send(), raw_append(), tcp_reass(), tcp_input(), and udp_append().
- When the socket buffer lock is dropped before a sowakeup(), remove the
explicit unlock and use the _locked() sowakeup() variant. This is done
in soisdisconnecting(), soisdisconnected() when setting the can't send/
receive flags and dropping data, and in uipc_rcvd() which adjusting
back-pressure on the sockets.
For UNIX domain sockets running mpsafe with a contention-intensive SMP
mysql benchmark, this results in a 1.6% query rate improvement due to
reduce mutex costs.
locking in tcp_input() for TCP packets with urgent data pointers to
hold the socket buffer lock across testing and updating oobmark
from just protecting sb_state.
Update socket locking annotations
the socket buffer having its limits adjusted. sbreserve() now acquires
the lock before calling sbreserve_locked(). In soreserve(), acquire
socket buffer locks across read-modify-writes of socket buffer fields,
and calls into sbreserve/sbrelease; make sure to acquire in keeping
with the socket buffer lock order. In tcp_mss(), acquire the socket
buffer lock in the calling context so that we have atomic read-modify
-write on buffer sizes.
originated on RELENG_4 and was ported to -CURRENT.
The scoreboarding code was obtained from OpenBSD, and many
of the remaining changes were inspired by OpenBSD, but not
taken directly from there.
You can enable/disable sack using net.inet.tcp.do_sack. You can
also limit the number of sack holes that all senders can have in
the scoreboard with net.inet.tcp.sackhole_limit.
Reviewed by: gnn
Obtained from: Yahoo! (Mohan Srinivasan, Jayanth Vijayaraghavan)
flags relating to several aspects of socket functionality. This change
breaks out several bits relating to send and receive operation into a
new per-socket buffer field, sb_state, in order to facilitate locking.
This is required because, in order to provide more granular locking of
sockets, different state fields have different locking properties. The
following fields are moved to sb_state:
SS_CANTRCVMORE (so_state)
SS_CANTSENDMORE (so_state)
SS_RCVATMARK (so_state)
Rename respectively to:
SBS_CANTRCVMORE (so_rcv.sb_state)
SBS_CANTSENDMORE (so_snd.sb_state)
SBS_RCVATMARK (so_rcv.sb_state)
This facilitates locking by isolating fields to be located with other
identically locked fields, and permits greater granularity in socket
locking by avoiding storing fields with different locking semantics in
the same short (avoiding locking conflicts). In the future, we may
wish to coallesce sb_state and sb_flags; for the time being I leave
them separate and there is no additional memory overhead due to the
packing/alignment of shorts in the socket buffer structure.
SOCK_LOCK(so):
- Hold socket lock over calls to MAC entry points reading or
manipulating socket labels.
- Assert socket lock in MAC entry point implementations.
- When externalizing the socket label, first make a thread-local
copy while holding the socket lock, then release the socket lock
to externalize to userspace.
uncommitted):
Rename ip_claim_next_hop() to m_claim_next_hop(), give it an extra arg
(the type of tag to claim) and push it out of ip_var.h into mbuf.h
alongside all of the other macros that work ok mbuf's and tag's.
possible while maintaining compatibility with the widest range of TCP stacks.
The algorithm is as follows:
---
For connections in the ESTABLISHED state, only resets with
sequence numbers exactly matching last_ack_sent will cause a reset,
all other segments will be silently dropped.
For connections in all other states, a reset anywhere in the window
will cause the connection to be reset. All other segments will be
silently dropped.
---
The necessity of accepting all in-window resets was discovered
by jayanth and jlemon, both of whom have seen TCP stacks that
will respond to FIN-ACK packets with resets not meeting the
strict last_ack_sent check.
Idea by: Darren Reed
Reviewed by: truckman, jlemon, others(?)
from tcp_hostcache would have overridden a (now) lower MTU of
an interface or route that changed since first PMTU discovery.
The bug would have caused TCP to redo the PMTU discovery when
not strictly necessary.
Make a comment about already pre-initialized default values
more clear.
Reviewed by: sam
amount of segments it will hold.
The following tuneables and sysctls control the behaviour of the tcp
segment reassembly queue:
net.inet.tcp.reass.maxsegments (loader tuneable)
specifies the maximum number of segments all tcp reassemly queues can
hold (defaults to 1/16 of nmbclusters).
net.inet.tcp.reass.maxqlen
specifies the maximum number of segments any individual tcp session queue
can hold (defaults to 48).
net.inet.tcp.reass.cursegments (readonly)
counts the number of segments currently in all reassembly queues.
net.inet.tcp.reass.overflows (readonly)
counts how often either the global or local queue limit has been reached.
Tested by: bms, silby
Reviewed by: bms, silby
them mostly with packet tags (one case is handled by using an mbuf flag
since the linkage between "caller" and "callee" is direct and there's no
need to incur the overhead of a packet tag).
This is (mostly) work from: sam
Silence from: -arch
Approved by: bms(mentor), sam, rwatson
This is the first of two commits; bringing in the kernel support first.
This can be enabled by compiling a kernel with options TCP_SIGNATURE
and FAST_IPSEC.
For the uninitiated, this is a TCP option which provides for a means of
authenticating TCP sessions which came into being before IPSEC. It is
still relevant today, however, as it is used by many commercial router
vendors, particularly with BGP, and as such has become a requirement for
interconnect at many major Internet points of presence.
Several parts of the TCP and IP headers, including the segment payload,
are digested with MD5, including a shared secret. The PF_KEY interface
is used to manage the secrets using security associations in the SADB.
There is a limitation here in that as there is no way to map a TCP flow
per-port back to an SPI without polluting tcpcb or using the SPD; the
code to do the latter is unstable at this time. Therefore this code only
supports per-host keying granularity.
Whilst FAST_IPSEC is mutually exclusive with KAME IPSEC (and thus IPv6),
TCP_SIGNATURE applies only to IPv4. For the vast majority of prospective
users of this feature, this will not pose any problem.
This implementation is output-only; that is, the option is honoured when
responding to a host initiating a TCP session, but no effort is made
[yet] to authenticate inbound traffic. This is, however, sufficient to
interwork with Cisco equipment.
Tested with a Cisco 2501 running IOS 12.0(27), and Quagga 0.96.4 with
local patches. Patches for tcpdump to validate TCP-MD5 sessions are also
available from me upon request.
Sponsored by: sentex.net
resource exhaustion attacks.
For network link optimization TCP can adjust its MSS and thus
packet size according to the observed path MTU. This is done
dynamically based on feedback from the remote host and network
components along the packet path. This information can be
abused to pretend an extremely low path MTU.
The resource exhaustion works in two ways:
o during tcp connection setup the advertized local MSS is
exchanged between the endpoints. The remote endpoint can
set this arbitrarily low (except for a minimum MTU of 64
octets enforced in the BSD code). When the local host is
sending data it is forced to send many small IP packets
instead of a large one.
For example instead of the normal TCP payload size of 1448
it forces TCP payload size of 12 (MTU 64) and thus we have
a 120 times increase in workload and packets. On fast links
this quickly saturates the local CPU and may also hit pps
processing limites of network components along the path.
This type of attack is particularly effective for servers
where the attacker can download large files (WWW and FTP).
We mitigate it by enforcing a minimum MTU settable by sysctl
net.inet.tcp.minmss defaulting to 256 octets.
o the local host is reveiving data on a TCP connection from
the remote host. The local host has no control over the
packet size the remote host is sending. The remote host
may chose to do what is described in the first attack and
send the data in packets with an TCP payload of at least
one byte. For each packet the tcp_input() function will
be entered, the packet is processed and a sowakeup() is
signalled to the connected process.
For example an attack with 2 Mbit/s gives 4716 packets per
second and the same amount of sowakeup()s to the process
(and context switches).
This type of attack is particularly effective for servers
where the attacker can upload large amounts of data.
Normally this is the case with WWW server where large POSTs
can be made.
We mitigate this by calculating the average MSS payload per
second. If it goes below 'net.inet.tcp.minmss' and the pps
rate is above 'net.inet.tcp.minmssoverload' defaulting to
1000 this particular TCP connection is resetted and dropped.
MITRE CVE: CAN-2004-0002
Reviewed by: sam (mentor)
MFC after: 1 day
rfc3042 Limited retransmit
rfc3390 Increasing TCP's initial congestion Window
inflight TCP inflight bandwidth limiting
All my production server have it enabled and there have been no
issues. I am confident about having them on by default and it gives
us better overall TCP performance.
Reviewed by: sam (mentor)
the routing table. Move all usage and references in the tcp stack
from the routing table metrics to the tcp hostcache.
It caches measured parameters of past tcp sessions to provide better
initial start values for following connections from or to the same
source or destination. Depending on the network parameters to/from
the remote host this can lead to significant speedups for new tcp
connections after the first one because they inherit and shortcut
the learning curve.
tcp_hostcache is designed for multiple concurrent access in SMP
environments with high contention and is hash indexed by remote
ip address.
It removes significant locking requirements from the tcp stack with
regard to the routing table.
Reviewed by: sam (mentor), bms
Reviewed by: -net, -current, core@kame.net (IPv6 parts)
Approved by: re (scottl)
the MAC label referenced from 'struct socket' in the IPv4 and
IPv6-based protocols. This permits MAC labels to be checked during
network delivery operations without dereferencing inp->inp_socket
to get to so->so_label, which will eventually avoid our having to
grab the socket lock during delivery at the network layer.
This change introduces 'struct inpcb' as a labeled object to the
MAC Framework, along with the normal circus of entry points:
initialization, creation from socket, destruction, as well as a
delivery access control check.
For most policies, the inpcb label will simply be a cache of the
socket label, so a new protocol switch method is introduced,
pr_sosetlabel() to notify protocols that the socket layer label
has been updated so that the cache can be updated while holding
appropriate locks. Most protocols implement this using
pru_sosetlabel_null(), but IPv4/IPv6 protocols using inpcbs use
the the worker function in_pcbsosetlabel(), which calls into the
MAC Framework to perform a cache update.
Biba, LOMAC, and MLS implement these entry points, as do the stub
policy, and test policy.
Reviewed by: sam, bms
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
o add assertions in tcp_respond to validate inpcb locking assumptions
o use local variable instead of chasing pointers in tcp_respond
Supported by: FreeBSD Foundation
in tcp_input that leave the function before hitting the tcp_trace
function call for the TCPDEBUG option. This has made TCPDEBUG mostly
useless (and tools like ports/benchmarks/dbs not working). Add
tcp_trace calls to the return paths that could be identified in this
maze.
This is a NOP unless you compile with TCPDEBUG.
lastest rev of the spec. Use an explicit flag for Fast Recovery. [1]
Fix bug with exiting Fast Recovery on a retransmit timeout
diagnosed by Lu Guohan. [2]
Reviewed by: Thomas Henderson <thomas.r.henderson@boeing.com>
Reported and tested by: Lu Guohan <lguohan00@mails.tsinghua.edu.cn> [2]
Approved by: Thomas Henderson <thomas.r.henderson@boeing.com>,
Sally Floyd <floyd@acm.org> [1]
sure that the MAC label on TCP responses during TIMEWAIT is
properly set from either the socket (if available), or the mbuf
that it's responding to.
Unfortunately, this is made somewhat difficult by the TCP code,
as tcp_twstart() calls tcp_twrespond() after discarding the socket
but without a reference to the mbuf that causes the "response".
Passing both the socket and the mbuf works arounds this--eventually
it might be good to make sure the mbuf always gets passed in in
"response" scenarios but working through this provided to
complicate things too much.
Approved by: re (scottl)
Reviewed by: hsu
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
doing Limited Transmit. Only artificially inflate the congestion
window by 1 segment instead of the usual 3 to take into account
the 2 already sent by Limited Transmit.
Approved in principle by: Mark Allman <mallman@grc.nasa.gov>,
Hari Balakrishnan <hari@nms.lcs.mit.edu>, Sally Floyd <floyd@icir.org>
that matches snd_max, then do not respond with an ack, just drop the
segment. This fixes a problem where a simultaneous close results in
an ack loop between two time-wait states.
Test case supplied by: Tim Robbins <tjr@FreeBSD.ORG>
Sponsored by: DARPA, NAI Labs
control block. Allow the socket and tcpcb structures to be freed
earlier than inpcb. Update code to understand an inp w/o a socket.
Reviewed by: hsu, silby, jayanth
Sponsored by: DARPA, NAI Labs
- delay acks for T/TCP regardless of delack setting
- fix bug where a single pass through tcp_input might not delay acks
- use callout_active() instead of callout_pending()
Sponsored by: DARPA, NAI Labs
Note that the original RFC 1323 (PAWS) says in 4.2.1 that the out of
order / reverse-time-indexed packet should be acknowledged as specified
in RFC-793 page 69 then dropped. The original PAWS code in FreeBSD (1994)
simply acknowledged the segment unconditionally, which is incorrect, and
was fixed in 1.183 (2002). At the moment we do not do checks for SYN or FIN
in addition to (tlen != 0), which may or may not be correct, but the
worst that ought to happen should be a retry by the sender.
apparent ack-on-ack problem with FreeBSD. Prof. Jacobson noticed a
case in our TCP stack which would acknowledge a received ack-only packet,
which is not legal in TCP.
Submitted by: Van Jacobson <van@packetdesign.com>,
bmah@packetdesign.com (Bruce A. Mah)
MFC after: 7 days
prediction code. Previously, 2GB worth of header predicted data
could leave these variables too far out of sequence which would cause
problems after receiving a packet that did not match the header
prediction.
Submitted by: Bill Baumann <bbaumann@isilon.com>
Sponsored by: Isilon Systems, Inc.
Reviewed by: hsu, pete@isilon.com, neal@isilon.com, aaronp@isilon.com
configuration stuff as well as conditional code in the IPv4 and IPv6
areas. Everything is conditional on FAST_IPSEC which is mutually
exclusive with IPSEC (KAME IPsec implmentation).
As noted previously, don't use FAST_IPSEC with INET6 at the moment.
Reviewed by: KAME, rwatson
Approved by: silence
Supported by: Vernier Networks
o instead of a list of mbufs use a list of m_tag structures a la openbsd
o for netgraph et. al. extend the stock openbsd m_tag to include a 32-bit
ABI/module number cookie
o for openbsd compatibility define a well-known cookie MTAG_ABI_COMPAT and
use this in defining openbsd-compatible m_tag_find and m_tag_get routines
o rewrite KAME use of aux mbufs in terms of packet tags
o eliminate the most heavily used aux mbufs by adding an additional struct
inpcb parameter to ip_output and ip6_output to allow the IPsec code to
locate the security policy to apply to outbound packets
o bump __FreeBSD_version so code can be conditionalized
o fixup ipfilter's call to ip_output based on __FreeBSD_version
Reviewed by: julian, luigi (silent), -arch, -net, darren
Approved by: julian, silence from everyone else
Obtained from: openbsd (mostly)
MFC after: 1 month
timestamped TCP packets where FreeBSD will send DATA+FIN and
A W2K box will ack just the DATA portion. If this occurs
after FreeBSD has done a (NewReno) fast-retransmit and is
recovering it (dupacks > threshold) it triggers a case in
tcp_newreno_partial_ack() (tcp_newreno() in stable) where
tcp_output() is called with the expectation that the retransmit
timer will be reloaded. But tcp_output() falls through and
returns without doing anything, causing the persist timer to be
loaded instead. This causes the connection to hang until W2K gives up.
This occurs because in the case where only the FIN must be acked, the
'len' calculation in tcp_output() will be 0, a lot of checks will be
skipped, and the FIN check will also be skipped because it is designed
to handle FIN retransmits, not forced transmits from tcp_newreno().
The solution is to simply set TF_ACKNOW before calling tcp_output()
to absolute guarentee that it will run the send code and reset the
retransmit timer. TF_ACKNOW is already used for this purpose in other
cases.
For some unknown reason this patch also seems to greatly reduce
the number of duplicate acks received when Guido runs his tests over
a lossy network. It is quite possible that there are other
tcp_newreno{_partial_ack()} cases which were not generating the expected
output which this patch also fixes.
X-MFC after: Will be MFC'd after the freeze is over
Windows 2000 box and a FreeBSD box could stall. The problem turned out
to be a timestamp reply bug in the W2K TCP stack. FreeBSD sends a
timestamp with the SYN, W2K returns a timestamp of 0 in the SYN+ACK
causing FreeBSD to calculate an insane SRTT and RTT, resulting in
a maximal retransmit timeout (60 seconds). If there is any packet
loss on the connection for the first six or so packets the retransmit
case may be hit (the window will still be too small for fast-retransmit),
causing a 60+ second pause. The W2K box gives up and closes the
connection.
This commit works around the W2K bug.
15:04:59.374588 FREEBSD.20 > W2K.1036: S 1420807004:1420807004(0) win 65535 <mss 1460,nop,wscale 2,nop,nop,timestamp 188297344 0> (DF) [tos 0x8]
15:04:59.377558 W2K.1036 > FREEBSD.20: S 4134611565:4134611565(0) ack 1420807005 win 17520 <mss 1460,nop,wscale 0,nop,nop,timestamp 0 0> (DF)
Bug reported by: Guido van Rooij <guido@gvr.org>
not meant to duplicate) TCP/Vegas. Add four sysctls and default the
implementation to 'off'.
net.inet.tcp.inflight_enable enable algorithm (defaults to 0=off)
net.inet.tcp.inflight_debug debugging (defaults to 1=on)
net.inet.tcp.inflight_min minimum window limit
net.inet.tcp.inflight_max maximum window limit
MFC after: 1 week
we can use the names _receive() and _send() for the receive() and send()
checks. Rename related constants, policy implementations, etc.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, NAI Labs
kernel access control.
Instrument the TCP socket code for packet generation and delivery:
label outgoing mbufs with the label of the socket, and check socket and
mbuf labels before permitting delivery to a socket. Assign labels
to newly accepted connections when the syncache/cookie code has done
its business. Also set peer labels as convenient. Currently,
MAC policies cannot influence the PCB matching algorithm, so cannot
implement polyinstantiation. Note that there is at least one case
where a PCB is not available due to the TCP packet not being associated
with any socket, so we don't label in that case, but need to handle
it in a special manner.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, NAI Labs
packet forwarding state ("annotations") during ip processing.
The code is considerably cleaner now.
The variables removed by this change are:
ip_divert_cookie used by divert sockets
ip_fw_fwd_addr used for transparent ip redirection
last_pkt used by dynamic pipes in dummynet
Removal of the first two has been done by carrying the annotations
into volatile structs prepended to the mbuf chains, and adding
appropriate code to add/remove annotations in the routines which
make use of them, i.e. ip_input(), ip_output(), tcp_input(),
bdg_forward(), ether_demux(), ether_output_frame(), div_output().
On passing, remove a bug in divert handling of fragmented packet.
Now it is the fragment at offset 0 which sets the divert status of
the whole packet, whereas formerly it was the last incoming fragment
to decide.
Removal of last_pkt required a change in the interface of ip_fw_chk()
and dummynet_io(). On passing, use the same mechanism for dummynet
annotations and for divert/forward annotations.
option IPFIREWALL_FORWARD is effectively useless, the code to
implement it is very small and is now in by default to avoid the
obfuscation of conditionally compiled code.
NOTES:
* there is at least one global variable left, sro_fwd, in ip_output().
I am not sure if/how this can be removed.
* I have deliberately avoided gratuitous style changes in this commit
to avoid cluttering the diffs. Minor stule cleanup will likely be
necessary
* this commit only focused on the IP layer. I am sure there is a
number of global variables used in the TCP and maybe UDP stack.
* despite the number of files touched, there are absolutely no API's
or data structures changed by this commit (except the interfaces of
ip_fw_chk() and dummynet_io(), which are internal anyways), so
an MFC is quite safe and unintrusive (and desirable, given the
improved readability of the code).
MFC after: 10 days
o Add a mutex (sb_mtx) to struct sockbuf. This protects the data in a
socket buffer. The mutex in the receive buffer also protects the data
in struct socket.
o Determine the lock strategy for each members in struct socket.
o Lock down the following members:
- so_count
- so_options
- so_linger
- so_state
o Remove *_locked() socket APIs. Make the following socket APIs
touching the members above now require a locked socket:
- sodisconnect()
- soisconnected()
- soisconnecting()
- soisdisconnected()
- soisdisconnecting()
- sofree()
- soref()
- sorele()
- sorwakeup()
- sotryfree()
- sowakeup()
- sowwakeup()
Reviewed by: alfred
Turn the sigio sx into a mutex.
Sigio lock is really only needed to protect interrupts from dereferencing
the sigio pointer in an object when the sigio itself is being destroyed.
In order to do this in the most unintrusive manner change pgsigio's
sigio * argument into a **, that way we can lock internally to the
function.
Requested by: bde
Since locking sigio_lock is usually followed by calling pgsigio(),
move the declaration of sigio_lock and the definitions of SIGIO_*() to
sys/signalvar.h.
While I am here, sort include files alphabetically, where possible.
of a socket. This avoids lock order reversal caused by locking a
process in pgsigio().
sowakeup() and the callers of it (sowwakeup, soisconnected, etc.) now
require sigio_lock to be locked. Provide sowwakeup_locked(),
soisconnected_locked(), and so on in case where we have to modify a
socket and wake up a process atomically.
were destined for a broadcast IP address. All TCP packets with a
broadcast destination must be ignored. The system only ignored packets
that were _link-layer_ broadcasts or multicast. We need to check the
IP address too since it is quite possible for a broadcast IP address
to come in with a unicast link-layer address.
Note that the check existed prior to CSRG revision 7.35, but was
removed. This commit effectively backs out that nine-year-old change.
PR: misc/35022
deprecated in favor of the POSIX-defined lowercase variants.
o Change all occurrences of NTOHL() and associated marcros in the
source tree to use the lowercase function variants.
o Add missing license bits to sparc64's <machine/endian.h>.
Approved by: jake
o Clean up <machine/endian.h> files.
o Remove unused __uint16_swap_uint32() from i386's <machine/endian.h>.
o Remove prototypes for non-existent bswapXX() functions.
o Include <machine/endian.h> in <arpa/inet.h> to define the
POSIX-required ntohl() family of functions.
o Do similar things to expose the ntohl() family in libstand, <netinet/in.h>,
and <sys/param.h>.
o Prepend underscores to the ntohl() family to help deal with
complexities associated with having MD (asm and inline) versions, and
having to prevent exposure of these functions in other headers that
happen to make use of endian-specific defines.
o Create weak aliases to the canonical function name to help deal with
third-party software forgetting to include an appropriate header.
o Remove some now unneeded pollution from <sys/types.h>.
o Add missing <arpa/inet.h> includes in userland.
Tested on: alpha, i386
Reviewed by: bde, jake, tmm
receiver was not sending an immediate ack with delayed acks turned on
when the input buffer is drained, preventing the transmitter from
restarting immediately.
Propogate the TCP_NODELAY option to accept()ed sockets. (Helps tbench and
is a good idea anyway).
Some cleanup. Identify additonal issues in comments.
MFC after: 1 day
Note ALL MODULES MUST BE RECOMPILED
make the kernel aware that there are smaller units of scheduling than the
process. (but only allow one thread per process at this time).
This is functionally equivalent to teh previousl -current except
that there is a thread associated with each process.
Sorry john! (your next MFC will be a doosie!)
Reviewed by: peter@freebsd.org, dillon@freebsd.org
X-MFC after: ha ha ha ha
new data is acknowledged, reset the dupacks to 0.
The problem was spotted when a connection had its send buffer full
because the congestion window was only 1 MSS and was not being incremented
because dupacks was not reset to 0.
Obtained from: Yahoo!
In order to ensure security and functionality, RFC 1948 style
initial sequence number generation has been implemented. Barring
any major crypographic breakthroughs, this algorithm should be
unbreakable. In addition, the problems with TIME_WAIT recycling
which affect our currently used algorithm are not present.
Reviewed by: jesper
generation scheme. Users may now select between the currently used
OpenBSD algorithm and the older random positive increment method.
While the OpenBSD algorithm is more secure, it also breaks TIME_WAIT
handling; this is causing trouble for an increasing number of folks.
To switch between generation schemes, one sets the sysctl
net.inet.tcp.tcp_seq_genscheme. 0 = random positive increments,
1 = the OpenBSD algorithm. 1 is still the default.
Once a secure _and_ compatible algorithm is implemented, this sysctl
will be removed.
Reviewed by: jlemon
Tested by: numerous subscribers of -net
connection. The information contained in a tcptemp can be
reconstructed from a tcpcb when needed.
Previously, tcp templates required the allocation of one
mbuf per connection. On large systems, this change should
free up a large number of mbufs.
Reviewed by: bmilekic, jlemon, ru
MFC after: 2 weeks
This work was based on kame-20010528-freebsd43-snap.tgz and some
critical problem after the snap was out were fixed.
There are many many changes since last KAME merge.
TODO:
- The definitions of SADB_* in sys/net/pfkeyv2.h are still different
from RFC2407/IANA assignment because of binary compatibility
issue. It should be fixed under 5-CURRENT.
- ip6po_m member of struct ip6_pktopts is no longer used. But, it
is still there because of binary compatibility issue. It should
be removed under 5-CURRENT.
Reviewed by: itojun
Obtained from: KAME
MFC after: 3 weeks
One way we can reduce the amount of traffic we send in response to a SYN
flood is to eliminate the RST we send when removing a connection from
the listen queue. Since we are being flooded, we can assume that the
majority of connections in the queue are bogus. Our RST is unwanted
by these hosts, just as our SYN-ACK was. Genuine connection attempts
will result in hosts responding to our SYN-ACK with an ACK packet. We
will automatically return a RST response to their ACK when it gets to us
if the connection has been dropped, so the early RST doesn't serve the
genuine class of connections much. In summary, we can reduce the number
of packets we send by a factor of two without any loss in functionality
by ensuring that RST packets are not sent when dropping a connection
from the listen queue.
Submitted by: Mike Silbersack <silby@silby.com>
Reviewed by: jesper
MFC after: 2 weeks
very specific scenarios, and now that we have had net.inet.tcp.blackhole for
quite some time there is really no reason to use it any more.
(last of three commits)
connection, but send it immediately. Prior to this change, it was possible
to delay a delayed-ack for multiple times, resulting in degraded TCP
behavior in certain corner cases.
were performed to determine if the received packet should be reset. This
created erroneous ratelimiting and false alarms in some cases. The code
has now been reorganized so that the checks for validity come before
the call to badport_bandlim. Additionally, a few changes in the symbolic
names of the bandlim types have been made, as well as a clarification of
exactly which type each RST case falls under.
Submitted by: Mike Silbersack <silby@silby.com>
1. ICMP ECHO and TSTAMP replies are now rate limited.
2. RSTs generated due to packets sent to open and unopen ports
are now limited by seperate counters.
3. Each rate limiting queue now has its own description, as
follows:
Limiting icmp unreach response from 439 to 200 packets per second
Limiting closed port RST response from 283 to 200 packets per second
Limiting open port RST response from 18724 to 200 packets per second
Limiting icmp ping response from 211 to 200 packets per second
Limiting icmp tstamp response from 394 to 200 packets per second
Submitted by: Mike Silbersack <silby@silby.com>
only be checked if the system is currently performing New Reno style
fast recovery. However, this value was being checked regardless of the
NR state, with the end result being that the congestion window was never
opened.
Change the logic to check t_dupack instead; the only code path that
allows it to be nonzero at this point is NewReno, so if it is nonzero,
we are in fast recovery mode and should not touch the congestion window.
Tested by: phk
delete the cloned route that is associated with the connection.
This does not exhaust the routing table memory when the system
is under a SYN flood attack. The route entry is not deleted if there
is any prior information cached in it.
Reviewed by: Peter Wemm,asmodai
code retransmitting data from the wrong offset.
As a footnote, the newreno code was partially derived from NetBSD
and Tom Henderson <tomh@cs.berkeley.edu>
better recovery for multiple packet losses in a single window.
The algorithm can be toggled via the sysctl net.inet.tcp.newreno,
which defaults to "on".
Submitted by: Jayanth Vijayaraghavan <jayanth@yahoo-inc.com>
Now most big problem of IPv6 is getting IPv6 address
assignment.
6to4 solve the problem. 6to4 addr is defined like below,
2002: 4byte v4 addr : 2byte SLA ID : 8byte interface ID
The most important point of the address format is that an IPv4 addr
is embeded in it. So any user who has IPv4 addr can get IPv6 address
block with 2byte subnet space. Also, the IPv4 addr is used for
semi-automatic IPv6 over IPv4 tunneling.
With 6to4, getting IPv6 addr become dramatically easy.
The attached patch enable 6to4 extension, and confirmed to work,
between "Richard Seaman, Jr." <dick@tar.com> and me.
Approved by: jkh
Reviewed by: itojun
o Drop all broadcast and multicast source addresses in tcp_input.
o Enable ICMP_BANDLIM in GENERIC.
o Change default to 200/s from 100/s. This will still stop the attack, but
is conservative enough to do this close to code freeze.
This is not the optimal patch for the problem, but is likely the least
intrusive patch that can be made for this.
Obtained from: Don Lewis and Matt Dillon.
Reviewed by: freebsd-security
-opt_ipsec.h was missing on some tcp files (sorry for basic mistake)
-made buildable as above fix
-also added some missing IPv4 mapped IPv6 addr consideration into
ipsec4_getpolicybysock
pr_input() routines prototype is also changed to support IPSEC and IPV6
chained protocol headers.
Reviewed by: freebsd-arch, cvs-committers
Obtained from: KAME project
packet divert at kernel for IPv6/IPv4 translater daemon
This includes queue related patch submitted by jburkhol@home.com.
Submitted by: queue related patch from jburkhol@home.com
Reviewed by: freebsd-arch, cvs-committers
Obtained from: KAME project
- eliminate the fast/slow timeout lists for TCP and instead use a
callout entry for each timer.
- increase the TCP timer granularity to HZ
- implement "bad retransmit" recovery, as presented in
"On Estimating End-to-End Network Path Properties", by Allman and Paxson.
Submitted by: jlemon, wollmann
drop any segment arriving at a closed port.
tcp.blackhole=1 - only drop SYN without RST
tcp.blackhole=2 - drop everything without RST
tcp.blackhole=0 - always send RST - default behaviour
This confuses nmap -sF or -sX or -sN quite badly.
sysctl knobs.
With these knobs on, refused connection attempts are dropped
without sending a RST, or Port unreachable in the UDP case.
In the TCP case, sending of RST is inhibited iff the incoming
segment was a SYN.
Docs and rc.conf settings to follow.
This was missed in the 4.4-Lite2 merge.
Noticed by: Mohan Parthasarathy <Mohan.Parthasarathy@eng.Sun.COM> and
jayanth@loc201.tandem.com (vijayaraghavan_jayanth)
on the tcp-impl mailing list.
Add ICMP_BANDLIM option and 'net.inet.icmp.icmplim' sysctl. If option
is specified in kernel config, icmplim defaults to 100 pps. Setting it
to 0 will disable the feature. This feature limits ICMP error responses
for packets sent to bad tcp or udp ports, which does a lot to help the
machine handle network D.O.S. attacks.
The kernel will report packet rates that exceed the limit at a rate of
one kernel printf per second. There is one issue in regards to the
'tail end' of an attack... the kernel will not output the last report
until some unrelated and valid icmp error packet is return at some
point after the attack is over. This is a minor reporting issue only.
Any packet that can be matched by a ipfw rule can be redirected
transparently to another port or machine. Redirection to another port
mostly makes sense with tcp, where a session can be set up
between a proxy and an unsuspecting client. Redirection to another machine
requires that the other machine also be expecting to receive the forwarded
packets, as their headers will not have been modified.
/sbin/ipfw must be recompiled!!!
Reviewed by: Peter Wemm <peter@freebsd.org>
Submitted by: Chrisy Luke <chrisy@flix.net>
connect. This check was added as part of the defense against the "land"
attack, to prevent attacks which guess the ISS from going into ESTABLISHED.
The "src == dst" check will still prevent the single-homed case of the
"land" attack, and guessing ISS's should be hard anyway.
Submitted by: David Borman <dab@bsdi.com>
a hashed port list. In the new scheme, in_pcblookup() goes away and is
replaced by a new routine, in_pcblookup_local() for doing the local port
check. Note that this implementation is space inefficient in that the PCB
struct is now too large to fit into 128 bytes. I might deal with this in the
future by using the new zone allocator, but I wanted these changes to be
extensively tested in their current form first.
Also:
1) Fixed off-by-one errors in the port lookup loops in in_pcbbind().
2) Got rid of some unneeded rehashing. Adding a new routine, in_pcbinshash()
to do the initialial hash insertion.
3) Renamed in_pcblookuphash() to in_pcblookup_hash() for easier readability.
4) Added a new routine, in_pcbremlists() to remove the PCB from the various
hash lists.
5) Added/deleted comments where appropriate.
6) Removed unnecessary splnet() locking. In general, the PCB functions should
be called at splnet()...there are unfortunately a few exceptions, however.
7) Reorganized a few structs for better cache line behavior.
8) Killed my TCP_ACK_HACK kludge. It may come back in a different form in
the future, however.
These changes have been tested on wcarchive for more than a month. In tests
done here, connection establishment overhead is reduced by more than 50
times, thus getting rid of one of the major networking scalability problems.
Still to do: make tcp_fastimo/tcp_slowtimo scale well for systems with a
large number of connections. tcp_fastimo is easy; tcp_slowtimo is difficult.
WARNING: Anything that knows about inpcb and tcpcb structs will have to be
recompiled; at the very least, this includes netstat(1).
rev 1.66. This fix contains both belt and suspenders.
Belt: ignore packets where src == dst and srcport == dstport in TCPS_LISTEN.
These packets can only legitimately occur when connecting a socket to itself,
which doesn't go through TCPS_LISTEN (it goes CLOSED->SYN_SENT->SYN_RCVD->
ESTABLISHED). This prevents the "standard" "land" attack, although doesn't
prevent the multi-homed variation.
Suspenders: send a RST in response to a SYN/ACK in SYN_RECEIVED state.
The only packets we should get in SYN_RECEIVED are
1. A retransmitted SYN, or
2. An ack of our SYN/ACK.
The "land" attack depends on us accepting our own SYN/ACK as an ACK;
in SYN_RECEIVED state; this should prevent all "land" attacks.
We also move up the sequence number check for the ACK in SYN_RECEIVED.
This neither helps nor hurts with respect to the "land" attack, but
puts more of the validation checking in one spot.
PR: kern/5103
RST's being ignored, keeping a connection around until it times out, and
thus has the opposite effect of what was intended (which is to make the
system more robust to DoS attacks).