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I noticed that only 3 out of the 4 input bits were used,
mt.key->flags & FLOW_DIS_IS_FRAGMENT was never checked.
In order to avoid a complicated maze, I converted it to
use a 16 byte mapping table.
As shown in the table below the old heuristics doesn't
always do the right thing, ie. when FLOW_DIS_IS_FRAGMENT=1/1
then it used to only match follow-up fragment packets.
Here are all the combinations, and their resulting new/old
VCAP key/mask filter:
/- FLOW_DIS_IS_FRAGMENT (key/mask)
| /- FLOW_DIS_FIRST_FRAG (key/mask)
| | /-- new VCAP fragment (key/mask)
v v v v- old VCAP fragment (key/mask)
0/0 0/0 -/- -/- impossible (due to entry cond. on mask)
0/0 0/1 -/- 0/3 !! invalid (can't match non-fragment + follow-up frag)
0/0 1/0 -/- -/- impossible (key > mask)
0/0 1/1 1/3 1/3 first fragment
0/1 0/0 0/3 3/3 !! not fragmented
0/1 0/1 0/3 3/3 !! not fragmented (+ not first fragment)
0/1 1/0 -/- -/- impossible (key > mask)
0/1 1/1 -/- 1/3 !! invalid (non-fragment and first frag)
1/0 0/0 -/- -/- impossible (key > mask)
1/0 0/1 -/- -/- impossible (key > mask)
1/0 1/0 -/- -/- impossible (key > mask)
1/0 1/1 -/- -/- impossible (key > mask)
1/1 0/0 1/1 3/3 !! some fragment
1/1 0/1 3/3 3/3 follow-up fragment
1/1 1/0 -/- -/- impossible (key > mask)
1/1 1/1 1/3 1/3 first fragment
In the datasheet the VCAP fragment values are documented as:
0 = no fragment
1 = initial fragment
2 = suspicious fragment
3 = valid follow-up fragment
Result: 3 combinations match the old behavior,
3 combinations have been corrected,
2 combinations are now invalid, and fail,
8 combinations are impossible.
It should now be aligned with how FLOW_DIS_IS_FRAGMENT
and FLOW_DIS_FIRST_FRAG is set in __skb_flow_dissect() in
net/core/flow_dissector.c
Since the VCAP fragment values are not a bitfield, we have
to ignore the suspicious fragment value, eg. when matching
on any kind of fragment with FLOW_DIS_IS_FRAGMENT=1/1.
Only compile tested, and logic tested in userspace, as I
unfortunately don't have access to this switch chip (yet).
Fixes:
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| 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 reStructuredText 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.