linux-kernel - Re: [PATCH] audit: remove unused macros

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Date:   Tue, 10 Nov 2020 21:47:07 -0500
From:   Paul Moore <paul@...l-moore.com>
To:     Alex Shi <alex.shi@...ux.alibaba.com>
Cc:     linux-audit@...hat.com, linux-kernel@...r.kernel.org,
        Richard Guy Briggs <rgb@...hat.com>
Subject: Re: [PATCH] audit: remove unused macros

On Tue, Nov 10, 2020 at 10:23 AM Richard Guy Briggs <rgb@...hat.com> wrote:
> On 2020-11-06 16:31, Alex Shi wrote:
> > Some unused macros could cause gcc warning:
> > kernel/audit.c:68:0: warning: macro "AUDIT_UNINITIALIZED" is not used
> > [-Wunused-macros]
> > kernel/auditsc.c:104:0: warning: macro "AUDIT_AUX_IPCPERM" is not used
> > [-Wunused-macros]
> > kernel/auditsc.c:82:0: warning: macro "AUDITSC_INVALID" is not used
> > [-Wunused-macros]
> >
> > remove them to tame gcc.
> >
> > Signed-off-by: Alex Shi <alex.shi@...ux.alibaba.com>
> > Cc: Paul Moore <paul@...l-moore.com>
> > Cc: Eric Paris <eparis@...hat.com>
> > Cc: linux-audit@...hat.com
> > Cc: linux-kernel@...r.kernel.org
> > ---
> >  kernel/audit.c   | 1 -
> >  kernel/auditsc.c | 3 ---
> >  2 files changed, 4 deletions(-)
> >
> > diff --git a/kernel/audit.c b/kernel/audit.c
> > index ac0aeaa99937..dfac1e0ca887 100644
> > --- a/kernel/audit.c
> > +++ b/kernel/audit.c
> > @@ -65,7 +65,6 @@
> >  /* No auditing will take place until audit_initialized == AUDIT_INITIALIZED.
> >   * (Initialization happens after skb_init is called.) */
> >  #define AUDIT_DISABLED               -1
> > -#define AUDIT_UNINITIALIZED  0
> >  #define AUDIT_INITIALIZED    1
> >  static int   audit_initialized;
>
> This one is part of a set, so it feels like it should stay, but the code
> is structured in such a way that it is not necessary.

Yes, I'd like for us to find a way to keep this if possible.  Let's
simply initialize "audit_initialized" to AUDIT_UNINITIALIZED in this
file.  At some point someone will surely complain about not needing to
initialize to zero, but we can deal with that later.

> > diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> > index 183d79cc2e12..eeb4930d499f 100644
> > --- a/kernel/auditsc.c
> > +++ b/kernel/auditsc.c
> > @@ -80,7 +80,6 @@
> >  #include "audit.h"
> >
> >  /* flags stating the success for a syscall */
> > -#define AUDITSC_INVALID 0
> >  #define AUDITSC_SUCCESS 1
> >  #define AUDITSC_FAILURE 2
>
> Same here, but this one should really be fixed by using
> AUDITSC_INVALID as the value assigned to context->return_valid in
> __audit_free() to avoid using magic numbers.

Agreed.

We could probably explicitly set it in audit_alloc_context() as well
if we wanted to be complete.

> Similarly, the compared
> values in audit_filter_rules() under the AUDIT_EXIT and AUDIT_SUCCESS
> cases should be "ctx->return_valid != AUDITSC_INVALID" rather than just
> "ctx->return_valid".  Same in audit_log_exit().

Agreed.

> > @@ -102,8 +101,6 @@ struct audit_aux_data {
> >       int                     type;
> >  };
> >
> > -#define AUDIT_AUX_IPCPERM    0
> > -
>
> Hmmm, this one looks like it was orphaned 15 years ago a couple of
> months after it was introduced due to this commit:
> c04049939f88 Steve Grubb <sgrubb@...hat.com> 2005-05-13
>     ("AUDIT: Add message types to audit records")
>
> Introduced here:
> 8e633c3fb2a2 David Woodhouse <dwmw2@...nybook.infradead.org> 2005-03-01
>     ("Audit IPC object owner/permission changes.")
>
> I agree, remove it.

No arguments from me.

--
paul moore
www.paul-moore.com