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Ihar Hrachyshka 23d268eb24 arp: honour gratuitous ARP _replies_
When arp_accept is 1, gratuitous ARPs are supposed to override matching
entries irrespective of whether they arrive during locktime. This was
implemented in commit 56022a8fdd ("ipv4: arp: update neighbour address
when a gratuitous arp is received and arp_accept is set")

There is a glitch in the patch though. RFC 2002, section 4.6, "ARP,
Proxy ARP, and Gratuitous ARP", defines gratuitous ARPs so that they can
be either of Request or Reply type. Those Reply gratuitous ARPs can be
triggered with standard tooling, for example, arping -A option does just
that.

This patch fixes the glitch, making both Request and Reply flavours of
gratuitous ARPs to behave identically.

As per RFC, if gratuitous ARPs are of Reply type, their Target Hardware
Address field should also be set to the link-layer address to which this
cache entry should be updated. The field is present in ARP over Ethernet
but not in IEEE 1394. In this patch, I don't consider any broadcasted
ARP replies as gratuitous if the field is not present, to conform the
standard. It's not clear whether there is such a thing for IEEE 1394 as
a gratuitous ARP reply; until it's cleared up, we will ignore such
broadcasts. Note that they will still update existing ARP cache entries,
assuming they arrive out of locktime time interval.

Signed-off-by: Ihar Hrachyshka <ihrachys@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-05-17 11:32:44 -04:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-05-15 15:50:49 -07:00
block Merge branch 'libnvdimm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm 2017-05-12 15:43:10 -07:00
certs scripts/spelling.txt: add "intialise(d)" pattern and fix typo instances 2017-05-08 17:15:13 -07:00
crypto treewide: use kv[mz]alloc* rather than opencoded variants 2017-05-08 17:15:13 -07:00
Documentation mm, docs: update memory.stat description with workingset* entries 2017-05-12 15:57:16 -07:00
drivers mlx5e: add CONFIG_INET dependency 2017-05-16 15:48:01 -04:00
firmware firmware/Makefile: force recompilation if makefile changes 2017-05-08 17:15:10 -07:00
fs Merge branch 'for-next' of git://git.samba.org/sfrench/cifs-2.6 2017-05-15 15:27:02 -07:00
include Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-05-15 15:50:49 -07:00
init Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-05-10 10:30:46 -07:00
ipc mm: introduce kv[mz]alloc helpers 2017-05-08 17:15:12 -07:00
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-05-15 15:50:49 -07:00
lib dmaengine updates for 4.12-rc1 2017-05-09 15:40:28 -07:00
mm mm: vmscan: scan until it finds eligible pages 2017-05-12 15:57:16 -07:00
net arp: honour gratuitous ARP _replies_ 2017-05-17 11:32:44 -04:00
samples samples/bpf: run cleanup routines when receiving SIGTERM 2017-05-11 21:43:30 -04:00
scripts Kbuild UAPI header export updates for v4.12 2017-05-10 20:45:36 -07:00
security Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-05-09 09:12:53 -07:00
sound sound fixes for 4.12-rc1 2017-05-12 12:10:38 -07:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-05-15 15:50:49 -07:00
usr initramfs: provide a way to ignore image provided by bootloader 2017-05-08 17:15:12 -07:00
virt Second round of KVM/ARM Changes for v4.12. 2017-05-09 12:51:49 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: Add support to generate LLVM assembly files 2017-04-25 08:13:52 +09:00
.mailmap power supply and reset changes for the v4.12 series (part 2) 2017-05-12 12:02:21 -07:00
COPYING
CREDITS avr32: remove support for AVR32 architecture 2017-05-01 09:27:15 +02:00
Kbuild kbuild: Consolidate header generation from ASM offset information 2017-04-13 05:43:37 +09:00
Kconfig
MAINTAINERS Tigran has moved 2017-05-12 15:57:15 -07:00
Makefile Linux 4.12-rc1 2017-05-13 13:19:49 -07:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.