3990408470
Using bpf_skc_lookup_tcp it's possible to ascertain whether a packet belongs to a known connection. However, there is one corner case: no sockets are created if SYN cookies are active. This means that the final ACK in the 3WHS is misclassified. Using the helper, we can look up the listening socket via bpf_skc_lookup_tcp and then check whether a packet is a valid SYN cookie ACK. Signed-off-by: Lorenz Bauer <lmb@cloudflare.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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.