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If a GSO skb is sent through a Geneve tunnel and if Geneve options are
added, the split GSO skb might not fit in the MTU anymore and an ICMP
frag needed packet can be generated. In such case the ICMP packet might
go through the segmentation logic (and dropped) later if it reaches a
path were the GSO status is checked and segmentation is required.
This is especially true when an OvS bridge is used with a Geneve tunnel
attached to it. The following set of actions could lead to the ICMP
packet being wrongfully segmented:
1. An skb is constructed by the TCP layer (e.g. gso_type SKB_GSO_TCPV4,
segs >= 2).
2. The skb hits the OvS bridge where Geneve options are added by an OvS
action before being sent through the tunnel.
3. When the skb is xmited in the tunnel, the split skb does not fit
anymore in the MTU and iptunnel_pmtud_build_icmp is called to
generate an ICMP fragmentation needed packet. This is done by reusing
the original (GSO!) skb. The GSO metadata is not cleared.
4. The ICMP packet being sent back hits the OvS bridge again and because
skb_is_gso returns true, it goes through queue_gso_packets...
5. ...where __skb_gso_segment is called. The skb is then dropped.
6. Note that in the above example on re-transmission the skb won't be a
GSO one as it would be segmented (len > MSS) and the ICMP packet
should go through.
Fix this by resetting the GSO information before reusing an skb in
iptunnel_pmtud_build_icmp and iptunnel_pmtud_build_icmpv6.
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 | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .pylintrc | ||
| .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.