linux-kernel - Re: [PATCH v3 17/30] liveupdate: luo_files: luo_ioctl: Unregister all FDs on device close

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] [day] [month] [year] [list]

Message-ID: <mafs0v7l9l3b1.fsf@kernel.org>
Date: Tue, 23 Sep 2025 15:13:38 +0200
From: Pratyush Yadav <pratyush@...nel.org>
To: Pasha Tatashin <pasha.tatashin@...een.com>
Cc: Pratyush Yadav <pratyush@...nel.org>,  jasonmiu@...gle.com,
  graf@...zon.com,  changyuanl@...gle.com,  rppt@...nel.org,
  dmatlack@...gle.com,  rientjes@...gle.com,  corbet@....net,
  rdunlap@...radead.org,  ilpo.jarvinen@...ux.intel.com,
  kanie@...ux.alibaba.com,  ojeda@...nel.org,  aliceryhl@...gle.com,
  masahiroy@...nel.org,  akpm@...ux-foundation.org,  tj@...nel.org,
  yoann.congal@...le.fr,  mmaurer@...gle.com,  roman.gushchin@...ux.dev,
  chenridong@...wei.com,  axboe@...nel.dk,  mark.rutland@....com,
  jannh@...gle.com,  vincent.guittot@...aro.org,  hannes@...xchg.org,
  dan.j.williams@...el.com,  david@...hat.com,  joel.granados@...nel.org,
  rostedt@...dmis.org,  anna.schumaker@...cle.com,  song@...nel.org,
  zhangguopeng@...inos.cn,  linux@...ssschuh.net,
  linux-kernel@...r.kernel.org,  linux-doc@...r.kernel.org,
  linux-mm@...ck.org,  gregkh@...uxfoundation.org,  tglx@...utronix.de,
  mingo@...hat.com,  bp@...en8.de,  dave.hansen@...ux.intel.com,
  x86@...nel.org,  hpa@...or.com,  rafael@...nel.org,  dakr@...nel.org,
  bartosz.golaszewski@...aro.org,  cw00.choi@...sung.com,
  myungjoo.ham@...sung.com,  yesanishhere@...il.com,
  Jonathan.Cameron@...wei.com,  quic_zijuhu@...cinc.com,
  aleksander.lobakin@...el.com,  ira.weiny@...el.com,
  andriy.shevchenko@...ux.intel.com,  leon@...nel.org,  lukas@...ner.de,
  bhelgaas@...gle.com,  wagi@...nel.org,  djeffery@...hat.com,
  stuart.w.hayes@...il.com,  lennart@...ttering.net,  brauner@...nel.org,
  linux-api@...r.kernel.org,  linux-fsdevel@...r.kernel.org,
  saeedm@...dia.com,  ajayachandra@...dia.com,  jgg@...dia.com,
  parav@...dia.com,  leonro@...dia.com,  witu@...dia.com
Subject: Re: [PATCH v3 17/30] liveupdate: luo_files: luo_ioctl: Unregister
 all FDs on device close

On Mon, Sep 22 2025, Pasha Tatashin wrote:

> On Wed, Aug 27, 2025 at 11:34 AM Pratyush Yadav <pratyush@...nel.org> wrote:
>>
>> Hi Pasha,
>>
>> On Thu, Aug 07 2025, Pasha Tatashin wrote:
>>
>> > Currently, a file descriptor registered for preservation via the remains
>> > globally registered with LUO until it is explicitly unregistered. This
>> > creates a potential for resource leaks into the next kernel if the
>> > userspace agent crashes or exits without proper cleanup before a live
>> > update is fully initiated.
>> >
>> > This patch ties the lifetime of FD preservation requests to the lifetime
>> > of the open file descriptor for /dev/liveupdate, creating an implicit
>> > "session".
>> >
>> > When the /dev/liveupdate file descriptor is closed (either explicitly
>> > via close() or implicitly on process exit/crash), the .release
>> > handler, luo_release(), is now called. This handler invokes the new
>> > function luo_unregister_all_files(), which iterates through all FDs
>> > that were preserved through that session and unregisters them.
>>
>> Why special case files here? Shouldn't you undo all the serialization
>> done for all the subsystems?
>
> Good point, subsystems should also be cancelled, and system should be
> brought back to normal state. However, with session support, we will
> be dropping only FDs that belong to a specific session when its FD is
> closed, or all FDs+subsystems when closing /dev/liveupdate.

Yeah, that makes sense.

[...]

-- 
Regards,
Pratyush Yadav