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a7e75e5ed4
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Lina Wang a7e75e5ed4 xfrm: fix tunnel model fragmentation behavior 
[ Upstream commit 4ff2980b6b ]

in tunnel mode, if outer interface(ipv4) is less, it is easily to let
inner IPV6 mtu be less than 1280. If so, a Packet Too Big ICMPV6 message
is received. When send again, packets are fragmentized with 1280, they
are still rejected with ICMPV6(Packet Too Big) by xfrmi_xmit2().

According to RFC4213 Section3.2.2:
if (IPv4 path MTU - 20) is less than 1280
	if packet is larger than 1280 bytes
		Send ICMPv6 "packet too big" with MTU=1280
                Drop packet
        else
		Encapsulate but do not set the Don't Fragment
                flag in the IPv4 header.  The resulting IPv4
                packet might be fragmented by the IPv4 layer
                on the encapsulator or by some router along
                the IPv4 path.
	endif
else
	if packet is larger than (IPv4 path MTU - 20)
        	Send ICMPv6 "packet too big" with
                MTU = (IPv4 path MTU - 20).
                Drop packet.
        else
                Encapsulate and set the Don't Fragment flag
                in the IPv4 header.
        endif
endif
Packets should be fragmentized with ipv4 outer interface, so change it.

After it is fragemtized with ipv4, there will be double fragmenation.
No.48 & No.51 are ipv6 fragment packets, No.48 is double fragmentized,
then tunneled with IPv4(No.49& No.50), which obey spec. And received peer
cannot decrypt it rightly.

48              2002::10        2002::11 1296(length) IPv6 fragment (off=0 more=y ident=0xa20da5bc nxt=50)
49   0x0000 (0) 2002::10        2002::11 1304         IPv6 fragment (off=0 more=y ident=0x7448042c nxt=44)
50   0x0000 (0) 2002::10        2002::11 200          ESP (SPI=0x00035000)
51              2002::10        2002::11 180          Echo (ping) request
52   0x56dc     2002::10        2002::11 248          IPv6 fragment (off=1232 more=n ident=0xa20da5bc nxt=50)

xfrm6_noneed_fragment has fixed above issues. Finally, it acted like below:
1   0x6206 192.168.1.138   192.168.1.1 1316 Fragmented IP protocol (proto=Encap Security Payload 50, off=0, ID=6206) [Reassembled in #2]
2   0x6206 2002::10        2002::11    88   IPv6 fragment (off=0 more=y ident=0x1f440778 nxt=50)
3   0x0000 2002::10        2002::11    248  ICMPv6    Echo (ping) request

Signed-off-by: Lina Wang <lina.wang@mediatek.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-04-08 14:39:47 +02:00
arch nds32: fix access_ok() checks in get/put_user 2022-03-28 09:57:10 +02:00
block block/wbt: fix negative inflight counter when remove scsi device 2022-02-23 12:01:04 +01:00
certs certs: Trigger creation of RSA module signing key if it's not an RSA key 2021-09-15 09:50:29 +02:00
crypto crypto: api - Move cryptomgr soft dependency into algapi 2022-02-11 09:09:03 +01:00
Documentation swiotlb: fix info leak with DMA_FROM_DEVICE 2022-04-08 14:39:46 +02:00
drivers HID: logitech-dj: add new lightspeed receiver id 2022-04-08 14:39:47 +02:00
fs exfat: avoid incorrectly releasing for root inode 2022-03-28 09:57:07 +02:00
include netdevice: add the case if dev is NULL 2022-04-08 14:39:47 +02:00
init bpf: Add kconfig knob for disabling unpriv bpf by default 2022-01-05 12:40:34 +01:00
ipc shm: extend forced shm destroy to support objects from several IPC nses 2021-12-01 09:19:10 +01:00
kernel swiotlb: fix info leak with DMA_FROM_DEVICE 2022-04-08 14:39:46 +02:00
lib ARM: 9178/1: fix unmet dependency on BITREVERSE for HAVE_ARCH_BITREVERSE 2022-03-19 13:44:44 +01:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
mm mm: swap: get rid of livelock in swapin readahead 2022-03-23 09:13:27 +01:00
net xfrm: fix tunnel model fragmentation behavior 2022-04-08 14:39:47 +02:00
samples ftrace/samples: Add missing prototypes direct functions 2022-01-11 15:25:00 +01:00
scripts kconfig: fix failing to generate auto.conf 2022-02-23 12:01:07 +01:00
security ima: Do not print policy rule with inactive LSM labels 2022-02-16 12:54:16 +01:00
sound ALSA: pci: fix reading of swapped values from pcmreg in AC97 codec 2022-03-28 09:57:09 +02:00
tools Revert "selftests/bpf: Add test for bpf_timer overwriting crash" 2022-03-23 09:13:30 +01:00
usr usr/include/Makefile: add linux/nfc.h to the compile-test coverage 2022-02-01 17:25:48 +01:00
virt KVM: eventfd: Fix false positive RCU usage warning 2022-02-16 12:54:20 +01:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore kbuild: generate Module.symvers only when vmlinux exists 2021-05-19 10:12:59 +02:00
.mailmap mailmap: add two more addresses of Uwe Kleine-König 2020-12-06 10:19:07 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Jason Cooper to CREDITS 2020-11-30 10:20:34 +01:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: adjust GCC PLUGINS after gcc-plugin.sh removal 2021-12-14 11:32:46 +01:00
Makefile Linux 5.10.109 2022-03-28 09:57:11 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

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

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

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.