linux-kernel - Re: [PATCH ghak84 v4] audit: purge audit_log

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Message-ID: <CAHC9VhQusQsdQc7EfdjdH5mp6qqqYVPHnG9nNhUhf3DS_cdWwA@mail.gmail.com>
Date:   Tue, 14 Jul 2020 16:29:30 -0400
From:   Paul Moore <paul@...l-moore.com>
To:     Richard Guy Briggs <rgb@...hat.com>, john.johansen@...onical.com
Cc:     Linux-Audit Mailing List <linux-audit@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux Security Module list 
        <linux-security-module@...r.kernel.org>,
        Eric Paris <eparis@...isplace.org>
Subject: Re: [PATCH ghak84 v4] audit: purge audit_log_string from the
 intra-kernel audit API

On Tue, Jul 14, 2020 at 1:44 PM Richard Guy Briggs <rgb@...hat.com> wrote:
> On 2020-07-14 12:21, Paul Moore wrote:
> > On Mon, Jul 13, 2020 at 3:52 PM Richard Guy Briggs <rgb@...hat.com> wrote:
> > >
> > > audit_log_string() was inteded to be an internal audit function and
> > > since there are only two internal uses, remove them.  Purge all external
> > > uses of it by restructuring code to use an existing audit_log_format()
> > > or using audit_log_format().
> > >
> > > Please see the upstream issue
> > > https://github.com/linux-audit/audit-kernel/issues/84
> > >
> > > Signed-off-by: Richard Guy Briggs <rgb@...hat.com>
> > > ---
> > > Passes audit-testsuite.
> > >
> > > Changelog:
> > > v4
> > > - use double quotes in all replaced audit_log_string() calls
> > >
> > > v3
> > > - fix two warning: non-void function does not return a value in all control paths
> > >         Reported-by: kernel test robot <lkp@...el.com>
> > >
> > > v2
> > > - restructure to piggyback on existing audit_log_format() calls, checking quoting needs for each.
> > >
> > > v1 Vlad Dronov
> > > - https://github.com/nefigtut/audit-kernel/commit/dbbcba46335a002f44b05874153a85b9cc18aebf
> > >
> > >  include/linux/audit.h     |  5 -----
> > >  kernel/audit.c            |  4 ++--
> > >  security/apparmor/audit.c | 10 ++++------
> > >  security/apparmor/file.c  | 25 +++++++------------------
> > >  security/apparmor/ipc.c   | 46 +++++++++++++++++++++++-----------------------
> > >  security/apparmor/net.c   | 14 ++++++++------
> > >  security/lsm_audit.c      |  4 ++--
> > >  7 files changed, 46 insertions(+), 62 deletions(-)
> >
> > Thanks for restoring the quotes, just one question below ...
> >
> > > diff --git a/security/apparmor/ipc.c b/security/apparmor/ipc.c
> > > index 4ecedffbdd33..fe36d112aad9 100644
> > > --- a/security/apparmor/ipc.c
> > > +++ b/security/apparmor/ipc.c
> > > @@ -20,25 +20,23 @@
> > >
> > >  /**
> > >   * audit_ptrace_mask - convert mask to permission string
> > > - * @buffer: buffer to write string to (NOT NULL)
> > >   * @mask: permission mask to convert
> > > + *
> > > + * Returns: pointer to static string
> > >   */
> > > -static void audit_ptrace_mask(struct audit_buffer *ab, u32 mask)
> > > +static const char *audit_ptrace_mask(u32 mask)
> > >  {
> > >         switch (mask) {
> > >         case MAY_READ:
> > > -               audit_log_string(ab, "read");
> > > -               break;
> > > +               return "read";
> > >         case MAY_WRITE:
> > > -               audit_log_string(ab, "trace");
> > > -               break;
> > > +               return "trace";
> > >         case AA_MAY_BE_READ:
> > > -               audit_log_string(ab, "readby");
> > > -               break;
> > > +               return "readby";
> > >         case AA_MAY_BE_TRACED:
> > > -               audit_log_string(ab, "tracedby");
> > > -               break;
> > > +               return "tracedby";
> > >         }
> > > +       return "";
> >
> > Are we okay with this returning an empty string ("") in this case?
> > Should it be a question mark ("?")?
> >
> > My guess is that userspace parsing should be okay since it still has
> > quotes, I'm just not sure if we wanted to use a question mark as we do
> > in other cases where the field value is empty/unknown.
>
> Previously, it would have been an empty value, not even double quotes.
> "?" might be an improvement.

Did you want to fix that now in this patch, or leave it to later?  As
I said above, I'm not too bothered by it with the quotes so either way
is fine by me.

John, I'm assuming you are okay with this patch?

-- 
paul moore
www.paul-moore.com