[PATCH v2] audit: add feature audit_lost reset

[Steve Grubb]

On Thursday, December 15, 2016 3:39:16 PM EST Paul Moore wrote:
> On Sat, Dec 10, 2016 at 6:52 AM, Richard Guy Briggs <rgb at redhat.com> wrote:
> > Add a method to reset the audit_lost value.
> > 
> > An AUDIT_SET message with the AUDIT_STATUS_LOST flag set by itself
> > will return a positive value repesenting the current audit_lost value
> > and reset the counter to zero.  If AUDIT_STATUS_LOST is not the
> > only flag set, the reset command will be ignored.  The value sent with
> > the command is ignored.
> > 
> > An AUDIT_LOST_RESET message will be sent to the listening audit daemon.
> > The data field will contain a u32 with the positive value of the
> > audit_lost value when it was reset.
> > 
> > See: https://github.com/linux-audit/audit-kernel/issues/3
> > 
> > Signed-off-by: Richard Guy Briggs <rgb at redhat.com>
> > ---
> > 
> >  include/uapi/linux/audit.h |    2 ++
> >  kernel/audit.c             |    8 +++++++-
> >  2 files changed, 9 insertions(+), 1 deletions(-)
> > 
> > diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
> > index 208df7b..6d38bff 100644
> > --- a/include/uapi/linux/audit.h
> > +++ b/include/uapi/linux/audit.h
> > @@ -70,6 +70,7 @@
> > 
> >  #define AUDIT_TTY_SET          1017    /* Set TTY auditing status */
> >  #define AUDIT_SET_FEATURE      1018    /* Turn an audit feature on or off
> >  */ #define AUDIT_GET_FEATURE      1019    /* Get which features are
> >  enabled */> 
> > +#define AUDIT_LOST_RESET       1020    /* Reset the audit_lost value */
> > 
> >  #define AUDIT_FIRST_USER_MSG   1100    /* Userspace messages mostly
> >  uninteresting to kernel */ #define AUDIT_USER_AVC         1107    /* We
> >  filter this differently */> 
> > @@ -325,6 +326,7 @@ enum {
> > 
> >  #define AUDIT_STATUS_RATE_LIMIT                0x0008
> >  #define AUDIT_STATUS_BACKLOG_LIMIT     0x0010
> >  #define AUDIT_STATUS_BACKLOG_WAIT_TIME 0x0020
> > 
> > +#define AUDIT_STATUS_LOST              0x0040
> > 
> >  #define AUDIT_FEATURE_BITMAP_BACKLOG_LIMIT     0x00000001
> >  #define AUDIT_FEATURE_BITMAP_BACKLOG_WAIT_TIME 0x00000002
> > 
> > diff --git a/kernel/audit.c b/kernel/audit.c
> > index f1ca116..19cfee0 100644
> > --- a/kernel/audit.c
> > +++ b/kernel/audit.c
> > @@ -122,7 +122,7 @@
> > 
> >     3) suppressed due to audit_rate_limit
> >     4) suppressed due to audit_backlog_limit
> >  
> >  */
> > 
> > -static atomic_t    audit_lost = ATOMIC_INIT(0);
> > +static atomic_t        audit_lost = ATOMIC_INIT(0);
> > 
> >  /* The netlink socket. */
> >  static struct sock *audit_sock;
> > 
> > @@ -920,6 +920,12 @@ static int audit_receive_msg(struct sk_buff *skb,
> > struct nlmsghdr *nlh)> 
> >                         if (err < 0)
> >                         
> >                                 return err;
> >                 
> >                 }
> > 
> > +               if (s.mask == AUDIT_STATUS_LOST) {
> > +                       u32 lost = atomic_xchg(&audit_lost, 0);
> > +
> > +                       audit_send_reply(skb, seq, AUDIT_LOST_RESET, 0, 0,
> > &lost, sizeof(lost));
> I'm not sure it makes much sense to both return the lost value as a
> netlink return code as well as send a separate netlink message back to
> the controlling task with the same information.  What I meant earlier
> was that we would emit an audit record, similar to
> audit_log_config_change(), so that the audit log would not only have
> information that the status count was reset, but also the subject
> information necessary to associate the action with an individual.
> 
> Does that make sense?

I'm planning to replace all the config change logging with the 
audit_log_task_simple function I sent so that we have everything. Can we go 
ahead and pull that in so that we can start using it?

Thanks,
-Steve

> > +                       return lost;
> > +               }
> > 
> >                 break;
> >         
> >         }
> > 
> >         case AUDIT_GET_FEATURE:
> > --
> > 1.7.1
> > 
> > --
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