linux-kernel - Re: [PATCH v7 0/3] fanotify: Allow user space to pass back additional audit info

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Message-ID: <CAHC9VhQuD0UMYd12x9kOMwruDmQsyUFxQ8gJ3Q_qF6a58Lu+2Q@mail.gmail.com>
Date:   Tue, 7 Feb 2023 09:54:11 -0500
From:   Paul Moore <paul@...l-moore.com>
To:     Jan Kara <jack@...e.cz>
Cc:     Richard Guy Briggs <rgb@...hat.com>,
        Linux-Audit Mailing List <linux-audit@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-fsdevel@...r.kernel.org, linux-api@...r.kernel.org,
        Eric Paris <eparis@...isplace.org>,
        Steve Grubb <sgrubb@...hat.com>,
        Amir Goldstein <amir73il@...il.com>
Subject: Re: [PATCH v7 0/3] fanotify: Allow user space to pass back additional
 audit info

On Tue, Feb 7, 2023 at 7:09 AM Jan Kara <jack@...e.cz> wrote:
> On Fri 03-02-23 16:35:13, Richard Guy Briggs wrote:
> > The Fanotify API can be used for access control by requesting permission
> > event notification. The user space tooling that uses it may have a
> > complicated policy that inherently contains additional context for the
> > decision. If this information were available in the audit trail, policy
> > writers can close the loop on debugging policy. Also, if this additional
> > information were available, it would enable the creation of tools that
> > can suggest changes to the policy similar to how audit2allow can help
> > refine labeled security.
> >
> > This patchset defines a new flag (FAN_INFO) and new extensions that
> > define additional information which are appended after the response
> > structure returned from user space on a permission event.  The appended
> > information is organized with headers containing a type and size that
> > can be delegated to interested subsystems.  One new information type is
> > defined to audit the triggering rule number.
> >
> > A newer kernel will work with an older userspace and an older kernel
> > will behave as expected and reject a newer userspace, leaving it up to
> > the newer userspace to test appropriately and adapt as necessary.  This
> > is done by providing a a fully-formed FAN_INFO extension but setting the
> > fd to FAN_NOFD.  On a capable kernel, it will succeed but issue no audit
> > record, whereas on an older kernel it will fail.
> >
> > The audit function was updated to log the additional information in the
> > AUDIT_FANOTIFY record. The following are examples of the new record
> > format:
> >   type=FANOTIFY msg=audit(1600385147.372:590): resp=2 fan_type=1 fan_info=3137 subj_trust=3 obj_trust=5
> >   type=FANOTIFY msg=audit(1659730979.839:284): resp=1 fan_type=0 fan_info=0 subj_trust=2 obj_trust=2
>
> Thanks! I've applied this series to my tree.

While I think this version of the patchset is fine, for future
reference it would have been nice if you had waited for my ACK on
patch 3/3; while Steve maintains his userspace tools, I'm the one
responsible for maintaining the Linux Kernel's audit subsystem.

-- 
paul-moore.com