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2e5a6266fb
RT_TOS() only masks one of the two ECN bits. Therefore rpfilter_mt()
treats Not-ECT or ECT(1) packets in a different way than those with
ECT(0) or CE.
Reproducer:
Create two netns, connected with a veth:
$ ip netns add ns0
$ ip netns add ns1
$ ip link add name veth01 netns ns0 type veth peer name veth10 netns ns1
$ ip -netns ns0 link set dev veth01 up
$ ip -netns ns1 link set dev veth10 up
$ ip -netns ns0 address add 192.0.2.10/32 dev veth01
$ ip -netns ns1 address add 192.0.2.11/32 dev veth10
Add a route to ns1 in ns0:
$ ip -netns ns0 route add 192.0.2.11/32 dev veth01
In ns1, only packets with TOS 4 can be routed to ns0:
$ ip -netns ns1 route add 192.0.2.10/32 tos 4 dev veth10
Ping from ns0 to ns1 works regardless of the ECN bits, as long as TOS
is 4:
$ ip netns exec ns0 ping -Q 4 192.0.2.11 # TOS 4, Not-ECT
... 0% packet loss ...
$ ip netns exec ns0 ping -Q 5 192.0.2.11 # TOS 4, ECT(1)
... 0% packet loss ...
$ ip netns exec ns0 ping -Q 6 192.0.2.11 # TOS 4, ECT(0)
... 0% packet loss ...
$ ip netns exec ns0 ping -Q 7 192.0.2.11 # TOS 4, CE
... 0% packet loss ...
Now use iptable's rpfilter module in ns1:
$ ip netns exec ns1 iptables-legacy -t raw -A PREROUTING -m rpfilter --invert -j DROP
Not-ECT and ECT(1) packets still pass:
$ ip netns exec ns0 ping -Q 4 192.0.2.11 # TOS 4, Not-ECT
... 0% packet loss ...
$ ip netns exec ns0 ping -Q 5 192.0.2.11 # TOS 4, ECT(1)
... 0% packet loss ...
But ECT(0) and ECN packets are dropped:
$ ip netns exec ns0 ping -Q 6 192.0.2.11 # TOS 4, ECT(0)
... 100% packet loss ...
$ ip netns exec ns0 ping -Q 7 192.0.2.11 # TOS 4, CE
... 100% packet loss ...
After this patch, rpfilter doesn't drop ECT(0) and CE packets anymore.
Fixes:
|
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|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| 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.