netdev - Re: [PATCH RFC net-next 00/11] udp gso

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 18 Apr 2018 09:59:11 -0400
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     Sowmini Varadhan <sowmini.varadhan@...cle.com>
Cc:     "Samudrala, Sridhar" <sridhar.samudrala@...el.com>,
        Network Development <netdev@...r.kernel.org>,
        Willem de Bruijn <willemb@...gle.com>
Subject: Re: [PATCH RFC net-next 00/11] udp gso

> One thing that was not clear to me about the API: shouldn't UDP_SEGMENT
> just be automatically determined in the stack from the pmtu? Whats
> the motivation for the socket option for this? also AIUI this can be
> either a per-socket or a per-packet option?

I decided to let the application explicitly set segment size, to avoid
bugs from the application assuming a different MTU from the one
used in the kernel for segmentation.

With path MTU, it is too easy for a process to incorrectly assume
link MTU or stale path MTU. With the current interface, if a process
tries to assemble segments larger than relevant path MTU, the
send call will fail.

A process may also explicitly want to send a chain of packets
smaller than MTU.