linux-kernel - Re: [PATCH v1 1/2] audit: record fanotify event regardless of presence of rules

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Message-ID: <fb8db86ae7208a08277ddc0fb949419b@paul-moore.com>
Date: Fri, 11 Apr 2025 14:14:19 -0400
From: Paul Moore <paul@...l-moore.com>
To: Richard Guy Briggs <rgb@...hat.com>, Linux-Audit Mailing List <linux-audit@...ts.linux-audit.osci.io>, LKML <linux-kernel@...r.kernel.org>, linux-fsdevel@...r.kernel.org, Linux Kernel Audit Mailing List <audit@...r.kernel.org>
Cc: Eric Paris <eparis@...isplace.org>, Steve Grubb <sgrubb@...hat.com>, Richard Guy Briggs <rgb@...hat.com>, Jan Kara <jack@...e.cz>, Amir Goldstein <amir73il@...il.com>
Subject: Re: [PATCH v1 1/2] audit: record fanotify event regardless of presence  of rules

On Mar  5, 2025 Richard Guy Briggs <rgb@...hat.com> wrote:
> 
> When no audit rules are in place, fanotify event results are
> unconditionally dropped due to an explicit check for the existence of
> any audit rules.  Given this is a report from another security
> sub-system, allow it to be recorded regardless of the existence of any
> audit rules.
> 
> To test, install and run the fapolicyd daemon with default config.  Then
> as an unprivileged user, create and run a very simple binary that should
> be denied.  Then check for an event with
> 	ausearch -m FANOTIFY -ts recent
> 
> Link: https://issues.redhat.com/browse/RHEL-1367
> Signed-off-by: Richard Guy Briggs <rgb@...hat.com>
> Acked-by: Jan Kara <jack@...e.cz>
> ---
>  include/linux/audit.h | 8 +-------
>  kernel/auditsc.c      | 2 +-
>  2 files changed, 2 insertions(+), 8 deletions(-)
> 
> diff --git a/include/linux/audit.h b/include/linux/audit.h
> index 0050ef288ab3..d0c6f23503a1 100644
> --- a/include/linux/audit.h
> +++ b/include/linux/audit.h
> @@ -418,7 +418,7 @@ extern void __audit_log_capset(const struct cred *new, const struct cred *old);
>  extern void __audit_mmap_fd(int fd, int flags);
>  extern void __audit_openat2_how(struct open_how *how);
>  extern void __audit_log_kern_module(char *name);
> -extern void __audit_fanotify(u32 response, struct fanotify_response_info_audit_rule *friar);
> +extern void audit_fanotify(u32 response, struct fanotify_response_info_audit_rule *friar);
>  extern void __audit_tk_injoffset(struct timespec64 offset);
>  extern void __audit_ntp_log(const struct audit_ntp_data *ad);
>  extern void __audit_log_nfcfg(const char *name, u8 af, unsigned int nentries,
> @@ -525,12 +525,6 @@ static inline void audit_log_kern_module(char *name)
>  		__audit_log_kern_module(name);
>  }
>  
> -static inline void audit_fanotify(u32 response, struct fanotify_response_info_audit_rule *friar)
> -{
> -	if (!audit_dummy_context())
> -		__audit_fanotify(response, friar);
> -}

It seems like we should at least have an audit_enabled() check, yes?
We've had people complain about audit events being generated when audit
is disabled, any while we don't currently have such a check in place
here, I believe the dummy context check is doing that for us.

  static inline void audit_fanotify(...)
  {
    if (!audit_enabled)
      return;
    __audit_fanotify(...);
  }

>  static inline void audit_tk_injoffset(struct timespec64 offset)
>  {
>  	/* ignore no-op events */
> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index 0627e74585ce..936825114bae 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -2880,7 +2880,7 @@ void __audit_log_kern_module(char *name)
>  	context->type = AUDIT_KERN_MODULE;
>  }
>  
> -void __audit_fanotify(u32 response, struct fanotify_response_info_audit_rule *friar)
> +void audit_fanotify(u32 response, struct fanotify_response_info_audit_rule *friar)
>  {
>  	/* {subj,obj}_trust values are {0,1,2}: no,yes,unknown */
>  	switch (friar->hdr.type) {
> -- 
> 2.43.5

--
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