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From: Jan Kara <>
To: Matthew Bobrowski <>
Cc: Jan Kara <>,, Steve Grubb <>,
Subject: Re: [PATCH v2 1/1] fanotify: introduce new event flag FAN_EXEC
Date: Mon, 1 Oct 2018 12:58:03 +0200	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Thu 27-09-18 23:05:14, Matthew Bobrowski wrote:
> This is a reduced version of a patch that I originally submitted a while ago.
> In short, the fanotify API currently does not provide any means for user space
> programs to receive events specifically when a file has been opened with the
> intent to be executed. The FAN_EXEC flag will be set within the event mask when
> a object has been opened with one of the open flags being __FMODE_EXEC.
> Linux is used as an Operating System in some products, with an environment that
> can be certified under the Common Criteria Operating System Protection Profile
> (OSPP). This is a formal threat model for a class of technology. It requires
> specific countermeasures to mitigate threats. It requires documentation to
> explain how a product implements these countermeasures. It requires proof via a
> test suite to demonstrate that the requirements are met, observed and checked by
> an independent qualified third party. The latest set of requirements for OSPP
> v4.2 can be found here:
> If you look on page 58, you will see the following requirement:
> FPT_SRP_EXT.1 Software Restriction Policies   FPT_SRP_EXT.1.1
> The OS shall restrict execution to only programs which match an administrator
> specified [selection:
>         file path,
>         file digital signature,
>         version,
>         hash,
>         [assignment: other characteristics]
> ]
> This patch is to help aid in meeting this requirement.
> Signed-off-by: Matthew Bobrowski <>

I agree with Amir's points wrt API so I won't repeat those. But I have one
more API question:

You implement FS_EXEC as a flag that can get set for certain FAN_OPEN
events. That is a new API concept for fanotify. So far you can only request
event of a certain type and then you get the same flag back when the event
happens.  There is also a case of FAN_ONDIR where you can restrict set of
events only to events on a particular inode type but that's again
different. Hence my question: Is there a good reason why we don't create
FAN_OPEN_EXEC event that would trigger only on executable opens?

If someone is interested only in executable opens, he'd have less events to
care about. OTOH additional FS_EXEC flag is probably more flexible (e.g.
you can easily implement equivalent of FAN_OPEN_NOEXEC in userspace if you
wished). Just the inconsistency of the FS_EXEC and e.g. how we handle

Jan Kara <>

  parent reply	other threads:[~2018-10-01 17:35 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-27 13:05 [PATCH v2 1/1] fanotify: introduce new event flag FAN_EXEC Matthew Bobrowski
2018-09-27 13:57 ` Amir Goldstein
2018-09-28  1:27   ` Matthew Bobrowski
2018-09-28  5:39     ` Amir Goldstein
2018-10-01  8:21       ` Matthew Bobrowski
2018-10-01  9:13         ` Amir Goldstein
2018-10-01 10:58 ` Jan Kara [this message]
2018-10-01 14:01   ` Amir Goldstein
2018-10-02  9:24     ` Jan Kara
2018-10-02 10:37       ` Amir Goldstein
2018-10-03 15:40         ` Jan Kara
2018-10-03 16:18           ` Amir Goldstein
2018-10-03 16:33             ` Jan Kara
2018-10-03 20:45               ` Matthew Bobrowski
2018-10-07 11:13               ` Matthew Bobrowski
2018-10-07 13:40                 ` Amir Goldstein
2018-10-08  9:35                 ` Jan Kara
2018-10-02 11:50       ` Matthew Bobrowski
2018-10-03 15:45         ` Jan Kara
2018-10-01 11:06 ` Jan Kara

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