Re: [PATCH ghak59 V3 2/4] audit: add syscall information to CONFIG_CHANGE records

[Paul Moore]

On Tue, Jan 15, 2019 at 11:21 AM Richard Guy Briggs <rgb@xxxxxxxxxx> wrote:
>
> On 2019-01-14 17:58, Paul Moore wrote:
> > On Mon, Dec 10, 2018 at 5:18 PM Richard Guy Briggs <rgb@xxxxxxxxxx> wrote:
> > > Tie syscall information to all CONFIG_CHANGE calls since they are all a
> > > result of user actions.
> > >
> > > Exclude user records from syscall context:
> > > Since the function audit_log_common_recv_msg() is shared by a number of
> > > AUDIT_CONFIG_CHANGE and the entire range of AUDIT_USER_* record types,
> > > and since the AUDIT_CONFIG_CHANGE message type has been converted to a
> > > syscall accompanied record type, special-case the AUDIT_USER_* range of
> > > messages so they remain standalone records.
> > >
> > > See: https://github.com/linux-audit/audit-kernel/issues/59
> > > See: https://github.com/linux-audit/audit-kernel/issues/50
> > > Signed-off-by: Richard Guy Briggs <rgb@xxxxxxxxxx>
> > > ---
> > >  kernel/audit.c          | 27 +++++++++++++++++++--------
> > >  kernel/audit_fsnotify.c |  2 +-
> > >  kernel/audit_tree.c     |  2 +-
> > >  kernel/audit_watch.c    |  2 +-
> > >  kernel/auditfilter.c    |  2 +-
> > >  5 files changed, 23 insertions(+), 12 deletions(-)
> > >
> > > diff --git a/kernel/audit.c b/kernel/audit.c
> > > index 0e8026423fbd..a321fea94cc6 100644
> > > --- a/kernel/audit.c
> > > +++ b/kernel/audit.c
> > > @@ -1072,6 +1073,16 @@ static void audit_log_common_recv_msg(struct audit_buffer **ab, u16 msg_type)
> > >         audit_log_task_context(*ab);
> > >  }
> > >
> > > +static inline void audit_log_user_recv_msg(struct audit_buffer **ab, u16 msg_type)
> > > +{
> > > +       audit_log_common_recv_msg(NULL, ab, msg_type);
> > > +}
> >
> > This makes sense because this is used by "user" records ...
> >
> > > +static inline void audit_log_config_change_alt(struct audit_buffer **ab)
> > > +{
> > > +       audit_log_common_recv_msg(audit_context(), ab, AUDIT_CONFIG_CHANGE);
> > > +}
> >
> > ... and I don't believe this makes sense because there is no real
> > logical grouping with the callers like there is for
> > audit_log_user_recv_msg().
>
> I don't follow "logical grouping".  They are all CONFIG_CHANGE record
> prefixes with the current context.

The audit_log_user_recv_msg() callers have a logical grouping because
they are all user generated records which we've decided shouldn't be
associated with any audit records tied to the current task.

The audit_log_config_change_alt() callers seem only to be grouped by
the fact that they are share some common audit_log_config_change_alt()
parameters; they don't appear to have anything else in common.  Yes,
sometimes we do create functions like audit_log_config_change_alt()
for reasons such as these, but I don't believe it is necessary, or
desirable, in this particular patch(set).

My comments on your v2 of this patchset suggested the creation of
audit_log_user_recv_msg() instead of what you did with
__audit_log_common_recv_msg().  You made that suggested change for v3
- good - but with v3 you also introduced audit_log_config_change_alt -
not good.

Get rid of audit_log_config_change_alt() (respin, retest, etc.) and
post this revised single patch (the others in the patchset that are ok
are already in audit/next) and we can get it into audit/next.

> Can you suggest an alternate name or another way of sharing
> audit_log_common_recv_msg() since the only differences between the two
> are a NULL context vs current task's context and the message type.  I
> wasn't particularly happy with this name either.  I'd really like to
> refactor this with all the rest of the CONFIG_CHANGE records, but there
> is too much of a format difference to make it work without reordering or
> deleting useless fields.
>
> I know you had suggested making two different functions, but I think
> they are more similar than different and merit the common factored code.
>
> > paul moore
>
> - RGB
>
> --
> Richard Guy Briggs <rgb@xxxxxxxxxx>
> 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

-- 
paul moore
www.paul-moore.com