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

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Message-ID: <20200714174353.ds7lj3iisy67t2zu@madcap2.tricolour.ca>
Date:   Tue, 14 Jul 2020 13:43:53 -0400
From:   Richard Guy Briggs <rgb@...hat.com>
To:     Paul Moore <paul@...l-moore.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>, john.johansen@...onical.com
Subject: Re: [PATCH ghak84 v4] audit: purge audit_log_string from the
 intra-kernel audit API

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.

> paul moore

- RGB

--
Richard Guy Briggs <rgb@...hat.com>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635