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From:   Paul Moore <paul@paul-moore.com>
Date:   Mon, 2 May 2022 20:16:17 -0400
Message-ID: <CAHC9VhSwVS=u+FhDrC6QucZbm7B1PgFudLeYcT_C111OEEY3rg@mail.gmail.com>
Subject: Re: [PATCH v2 3/3] fanotify: Allow audit to use the full permission
 event response
To:     Richard Guy Briggs <rgb@redhat.com>
Cc:     Linux-Audit Mailing List <linux-audit@redhat.com>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-fsdevel@vger.kernel.org, Eric Paris <eparis@parisplace.org>,
        Steve Grubb <sgrubb@redhat.com>, Jan Kara <jack@suse.cz>
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On Thu, Apr 28, 2022 at 8:45 PM Richard Guy Briggs <rgb@redhat.com> wrote:
>
> This patch passes the full value so that the audit function can use all
> of it. The audit function was updated to log the additional information in
> the AUDIT_FANOTIFY record. The following is an example of the new record
> format:
>
> type=FANOTIFY msg=audit(1600385147.372:590): resp=2 fan_type=1 fan_ctx=17
>
> Suggested-by: Steve Grubb <sgrubb@redhat.com>
> Link: https://lore.kernel.org/r/3075502.aeNJFYEL58@x2
> Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
> Link: https://lore.kernel.org/r/23c7f206a465d88cc646a944515fcc6a365f5eb2.1651174324.git.rgb@redhat.com
> ---
>  fs/notify/fanotify/fanotify.c |  4 +++-
>  include/linux/audit.h         |  8 ++++----
>  kernel/auditsc.c              | 18 +++++++++++++++---
>  3 files changed, 22 insertions(+), 8 deletions(-)

...

> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index ea2ee1181921..afdbc416069a 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -64,6 +64,7 @@
>  #include <uapi/linux/limits.h>
>  #include <uapi/linux/netfilter/nf_tables.h>
>  #include <uapi/linux/openat2.h> // struct open_how
> +#include <uapi/linux/fanotify.h>
>
>  #include "audit.h"
>
> @@ -2893,10 +2894,21 @@ void __audit_log_kern_module(char *name)
>         context->type = AUDIT_KERN_MODULE;
>  }
>
> -void __audit_fanotify(unsigned int response)
> +void __audit_fanotify(__u16 response, __u16 type, char *buf)
>  {
> -       audit_log(audit_context(), GFP_KERNEL,
> -               AUDIT_FANOTIFY, "resp=%u", response);
> +       switch (type) {
> +       case FAN_RESPONSE_INFO_AUDIT_RULE:
> +               audit_log(audit_context(), GFP_KERNEL, AUDIT_FANOTIFY,
> +                         "resp=%u fan_type=%u fan_ctx=%u",
> +                         response, type, (__u32)*buf);

I think the above awkward cast helps the argument that
fanotify_response:extra_info_buf (and fanotify_perm_event) should
properly define a union to encapsulate the type specific data.  If you
defined a common union type you could share it among all of the
different users.


--
paul-moore.com