linux-kernel - Re: [1/2,v2] fdmap(2)

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <CACVxJT_ZP=VAJQ_=D1JV0yt3bT_RZjtWTW61KcV5gCbhF8ixBw@mail.gmail.com>
Date:   Wed, 18 Oct 2017 13:35:00 +0200
From:   Alexey Dobriyan <adobriyan@...il.com>
To:     Andrei Vagin <avagin@...tuozzo.com>
Cc:     akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
        linux-api@...r.kernel.org, rdunlap@...radead.org,
        tglx@...utronix.de, tixxdz@...il.com, gladkov.alexey@...il.com
Subject: Re: [1/2,v2] fdmap(2)

On 10/12/17, Andrei Vagin <avagin@...tuozzo.com> wrote:

> I'm agree with your points, but I think you choose a wrong set of data
> to make an example of a new approach.
>
> You are talking a lot about statx, but for me it is unclear how fdmap
> follows the idea of statx. Let's imagine that I want to extend fdmap to
> return mnt_id for each file descriptor?

fdmap() is standalone thing.

Next step is to design fdinfo(2) (?) which uses descriptors from fdmap(2).
Extending structures is done as usual: but version, add new fields to the end.

> Or it may be more complex case, when we decided to provide all data
> from /proc/pid/fdinfo/X for each descriptor. A set of fields in fdinfo
> depends on a type of a file descriptor, it is different for epoll,
> signalfd, inotify, sockets, etc.
>
> For inotify file descriptors, there are information about all watches,
> so it is not possible to use a fixed size struture to present this data.

Now I didn't look closely at inotify watches but this is done with unions,
zero-length trailing arrays, and other usual stuff. If OpenVZ/Virtuozzo is
doing C/R of inotify then you already have all serializing code.