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OPNsense - FreeBSD source
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I edited the original change to retain the use of arc4random() as a seed for the hashing as a very basic defense against intentional lagg port selection. The author's original commit message (edited slightly): sys/net/ieee8023ad_lacp.c sys/net/if_lagg.c In lagg_hashmbuf, use the FNV hash instead of the old hash32_buf. The hash32 family of functions operate one octet at a time, and when run on a string s of length n, their output is equivalent to : ----- i=n-1 \ n \ (n-i-1) 32 ( seed^ + / 33^ * s[i] ) % 2^ / ----- i=0 The problem is that the last five bytes of input don't get multiplied by sufficiently many powers of 33 to rollover 2^32. That means that changing the last few bytes (but obviously not the very last) of input will always change the value of the hash by a multiple of 33. In the case of lagg_hashmbuf() with ipv4 input, the last four bytes are the TCP or UDP port numbers. Since the output of lagg_hashmbuf is always taken modulo the port count, and 3 is a common port count for a lagg, that's bad. It means that the UDP or TCP source port will never affect which lagg member is selected on a 3-port lagg. At 10Gbps, I was not able to measure any difference in CPU consumption between the old and new hash. Submitted by: asomers (original commit) Reviewed by: emaste, glebius MFC after: 1 week Sponsored by: Spectra Logic MFSpectraBSD: 1001723 on 2013/08/28 (original) 1114258 on 2015/01/22 (edit) |
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| contrib | ||
| crypto | ||
| etc | ||
| games | ||
| gnu | ||
| include | ||
| kerberos5 | ||
| lib | ||
| libexec | ||
| release | ||
| rescue | ||
| sbin | ||
| secure | ||
| share | ||
| sys | ||
| tests | ||
| tools | ||
| usr.bin | ||
| usr.sbin | ||
| .arcconfig | ||
| .arclint | ||
| COPYRIGHT | ||
| LOCKS | ||
| MAINTAINERS | ||
| Makefile | ||
| Makefile.inc1 | ||
| ObsoleteFiles.inc | ||
| README | ||
| UPDATING | ||
This is the top level of the FreeBSD source directory. This file was last revised on: $FreeBSD$ For copyright information, please see the file COPYRIGHT in this directory (additional copyright information also exists for some sources in this tree - please see the specific source directories for more information). The Makefile in this directory supports a number of targets for building components (or all) of the FreeBSD source tree, the most commonly used one being ``world'', which rebuilds and installs everything in the FreeBSD system from the source tree except the kernel, the kernel-modules and the contents of /etc. The ``world'' target should only be used in cases where the source tree has not changed from the currently running version. See: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/makeworld.html for more information, including setting make(1) variables. The ``buildkernel'' and ``installkernel'' targets build and install the kernel and the modules (see below). Please see the top of the Makefile in this directory for more information on the standard build targets and compile-time flags. Building a kernel is a somewhat more involved process, documentation for which can be found at: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kernelconfig.html And in the config(8) man page. Note: If you want to build and install the kernel with the ``buildkernel'' and ``installkernel'' targets, you might need to build world before. More information is available in the handbook. The sample kernel configuration files reside in the sys/<arch>/conf sub-directory (assuming that you've installed the kernel sources), the file named GENERIC being the one used to build your initial installation kernel. The file NOTES contains entries and documentation for all possible devices, not just those commonly used. It is the successor of the ancient LINT file, but in contrast to LINT, it is not buildable as a kernel but a pure reference and documentation file. Source Roadmap: --------------- bin System/user commands. cddl Various commands and libraries under the Common Development and Distribution License. contrib Packages contributed by 3rd parties. crypto Cryptography stuff (see crypto/README). etc Template files for /etc. games Amusements. gnu Various commands and libraries under the GNU Public License. Please see gnu/COPYING* for more information. include System include files. kerberos5 Kerberos5 (Heimdal) package. lib System libraries. libexec System daemons. release Release building Makefile & associated tools. rescue Build system for statically linked /rescue utilities. sbin System commands. secure Cryptographic libraries and commands. share Shared resources. sys Kernel sources. tools Utilities for regression testing and miscellaneous tasks. usr.bin User commands. usr.sbin System administration commands. For information on synchronizing your source tree with one or more of the FreeBSD Project's development branches, please see: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/synching.html