LKML Archive on
help / color / mirror / Atom feed
From: Amir Goldstein <>
To: Christian Brauner <>
Cc: Jan Kara <>,
	linux-fsdevel <>,
	linux-kernel <>
Subject: Re: [PATCH] fanotify: remove redundant capable(CAP_SYS_ADMIN)s
Date: Wed, 22 May 2019 21:29:37 +0300	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Wed, May 22, 2019 at 7:32 PM Christian Brauner <> wrote:
> This removes two redundant capable(CAP_SYS_ADMIN) checks from
> fanotify_init().
> fanotify_init() guards the whole syscall with capable(CAP_SYS_ADMIN) at the
> beginning. So the other two capable(CAP_SYS_ADMIN) checks are not needed.

It's intentional:

commit e7099d8a5a34d2876908a9fab4952dabdcfc5909
Author: Eric Paris <>
Date:   Thu Oct 28 17:21:57 2010 -0400

    fanotify: limit the number of marks in a single fanotify group

    There is currently no limit on the number of marks a given fanotify group
    can have.  Since fanotify is gated on CAP_SYS_ADMIN this was not seen as
    a serious DoS threat.  This patch implements a default of 8192, the same as
    inotify to work towards removing the CAP_SYS_ADMIN gating and eliminating
    the default DoS'able status.

    Signed-off-by: Eric Paris <>

There idea is to eventually remove the gated CAP_SYS_ADMIN.
There is no reason that fanotify could not be used by unprivileged users
to setup inotify style watch on an inode or directories children, see:

> Fixes: 5dd03f55fd2 ("fanotify: allow userspace to override max queue depth")
> Fixes: ac7e22dcfaf ("fanotify: allow userspace to override max marks")

Fixes is used to tag bug fixes for stable.
There is no bug.


  reply	other threads:[~2019-05-22 18:29 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-22 16:31 Christian Brauner
2019-05-22 18:29 ` Amir Goldstein [this message]
2019-05-22 18:57   ` Christian Brauner
2019-05-22 20:00     ` Amir Goldstein
2019-05-23  9:55       ` Christian Brauner
2019-05-23 10:25         ` Amir Goldstein
2019-05-23 10:42           ` Christian Brauner
2019-05-23 11:40             ` Amir Goldstein
2019-05-23 11:58               ` Christian Brauner
2019-05-23 13:16                 ` Amir Goldstein
2019-05-23 13:35                   ` Christian Brauner
2019-05-23 14:40                     ` Jan Kara
2019-05-23 14:43                       ` Christian Brauner
2019-05-23 15:15                       ` Amir Goldstein
2019-06-05 10:26           ` Matthew Bobrowski

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='' \ \ \ \ \ \
    --subject='Re: [PATCH] fanotify: remove redundant capable(CAP_SYS_ADMIN)s' \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).