Commit Graph

24 Commits

Author SHA1 Message Date
Warner Losh
f36cfd49ad Remove advertising clause from University of California Regent's
license, per letter dated July 22, 1999 and email from Peter Wemm,
Alan Cox and Robert Watson.

Approved by: core, peter, alc, rwatson
2004-04-07 20:46:16 +00:00
Bruce M Simpson
88f6b0435e Shorten the name of the socket option used to enable TCP-MD5 packet
treatment.

Submitted by:	Vincent Jardin
2004-02-16 22:21:16 +00:00
Bruce M Simpson
1cfd4b5326 Initial import of RFC 2385 (TCP-MD5) digest support.
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
2004-02-11 04:26:04 +00:00
Andre Oppermann
bed824fa90 Disable the minmssoverload connection drop by default until the detection
logic is refined.
2004-01-12 15:46:04 +00:00
Andre Oppermann
1ddc17c1d5 Reduce TCP_MINMSS default to 216. The AX.25 protocol (packet radio)
is frequently used with an MTU of 256 because of slow speeds and a
high packet loss rate.
2004-01-09 14:14:10 +00:00
Andre Oppermann
53369ac9bb Limiters and sanity checks for TCP MSS (maximum segement size)
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
2004-01-08 17:40:07 +00:00
Mike Barcroft
c0ec31f93e Include <sys/cdefs.h> so the visibility conditionals are available.
(This should have been included with the previous revision.)
2002-10-02 04:22:34 +00:00
Mike Barcroft
0cd4a9031e Use visibility conditionals. Only TCP_NODELAY ends up being defined
in the standards case.
2002-10-02 04:19:47 +00:00
Robert Watson
46a27060af o Minor style(9)ism to make consistent with -STABLE 2001-01-09 18:26:17 +00:00
Robert Watson
65450f2f77 o IPFW incorrectly handled filtering in the presence of previously
reserved and now allocated TCP flags in incoming packets.  This patch
  stops overloading those bits in the IP firewall rules, and moves
  colliding flags to a seperate field, ipflg.  The IPFW userland
  management tool, ipfw(8), is updated to reflect this change.  New TCP
  flags related to ECN are now included in tcp.h for reference, although
  we don't currently implement TCP+ECN.

o To use this fix without completely rebuilding, it is sufficient to copy
  ip_fw.h and tcp.h into your appropriate include directory, then rebuild
  the ipfw kernel module, and ipfw tool, and install both.  Note that a
  mismatch between module and userland tool will result in incorrect
  installation of firewall rules that may have unexpected effects.  This
  is an MFC candidate, following shakedown.  This bug does not appear
  to affect ipfilter.

Reviewed by:	security-officer, billf
Reported by:	Aragon Gouveia <aragon@phat.za.net>
2001-01-09 03:10:30 +00:00
Jonathan Lemon
46f5848237 Implement TCP NewReno, as documented in RFC 2582. This allows
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>
2000-05-06 03:31:09 +00:00
Yoshinobu Inoue
fb59c426ff tcp updates to support IPv6.
also a small patch to sys/nfs/nfs_socket.c, as max_hdr size change.

Reviewed by: freebsd-arch, cvs-committers
Obtained from: KAME project
2000-01-09 19:17:30 +00:00
Yoshinobu Inoue
76429de41a KAME related header files additions and merges.
(only those which don't affect c source files so much)

Reviewed by: cvs-committers
Obtained from: KAME project
1999-11-05 14:41:39 +00:00
Peter Wemm
c3aac50f28 $Id$ -> $FreeBSD$ 1999-08-28 01:08:13 +00:00
Bruce Evans
07a4df4fee Declare tcp_seq and tcp_cc as fixed-size types. Half fixed type
mismatches exposed by this (the prototype for tcp_respond() didn't
match the  function definition lexically, and still depends on a
gcc feature to match if ints have more than 32 bits).
1998-07-13 11:09:52 +00:00
Bruce Evans
a09bee1aa8 Fixed pedantic semantics errors (bitfields not of type int, signed int
or unsigned int (this doesn't change the struct layout, size or
alignment in any of the files changed in this commit, at least for
gcc on i386's.  Using bitfields of type u_char may affect size and
alignment but not packing)).
1998-06-08 09:47:47 +00:00
Peter Wemm
6875d25465 Back out part 1 of the MCFH that changed $Id$ to $FreeBSD$. We are not
ready for it yet.
1997-02-22 09:48:43 +00:00
Jordan K. Hubbard
1130b656e5 Make the long-awaited change from $Id$ to $FreeBSD$
This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.

Boy, I'm glad we're not using sup anymore.  This update would have been
insane otherwise.
1997-01-14 07:20:47 +00:00
Rodney W. Grimes
9b2e535452 Remove trailing whitespace. 1995-05-30 08:16:23 +00:00
Garrett Wollman
2f96f1f446 Get rid of some unneeded #ifdef TTCP lines. Also, get rid of some
bogus commons declared in header files.
1995-02-14 02:35:19 +00:00
Garrett Wollman
eb6ad69646 Merge in T/TCP TCP header file changes. 1995-02-08 20:18:48 +00:00
Paul Richards
707f139edb Made idempotent.
Submitted by:	Paul
1994-08-21 05:27:42 +00:00
David Greenman
3c4dd3568f Added $Id$ 1994-08-02 07:55:43 +00:00
Rodney W. Grimes
df8bae1de4 BSD 4.4 Lite Kernel Sources 1994-05-24 10:09:53 +00:00