Re: proposing [PATCH] audit: get rid of *NO* daemon at audit_pid=0 message

[Steve Grubb <sgrubb@redhat.com>]

On Monday, November 11, 2013 12:21:33 PM Eric Paris wrote:
> On Wed, 2013-10-30 at 00:05 +0100, Mateusz Guzik wrote:
> > Hello,
> > 
> > I wrote a trivial patch for what I believe is a subsystem you maintain.
> > 
> > I'm sending it privately first to ensure it looks ok at has proper
> > recipients (I'm new to linux world, sorry :>).
> > 
> > 'To' would be: linux-audit@redhat.com
> > 
> > The rest is:
> > 
> > From: Mateusz Guzik <mguzik@redhat.com>
> > Date: Tue, 29 Oct 2013 23:51:52 +0100
> > Subject: [PATCH] audit: get rid of *NO* daemon at audit_pid=0 message
> > 
> > kauditd_send_skb is called after audit_pid was checked to be non-zero.
> > 
> > However, it can be set to 0 due to auditd exiting while kauditd_send_skb
> > is still executed and this can result in a spurious warning about missing
> > auditd.

Is it really spurious? Meaning an admin at a site making heavy use of the 
audit subsystem would never want to know this? Are the events always put back 
with no chance of loss?

-Steve

 
> > Re-check audit_pid before printing the message.
> > 
> > Signed-off-by: Mateusz Guzik <mguzik@redhat.com>
> > Cc: Eric Paris <eparis@redhat.com>
> > Cc: linux-kernel@vger.kernel.org
> 
> Acked-by: Eric Paris <eparis@redhat.com>
> 
> > ---
> > 
> >  kernel/audit.c | 8 +++++---
> >  1 file changed, 5 insertions(+), 3 deletions(-)
> > 
> > diff --git a/kernel/audit.c b/kernel/audit.c
> > index 7b0e23a..a91a965 100644
> > --- a/kernel/audit.c
> > +++ b/kernel/audit.c
> > @@ -388,9 +388,11 @@ static void kauditd_send_skb(struct sk_buff *skb)
> > 
> >  	err = netlink_unicast(audit_sock, skb, audit_nlk_portid, 0);
> >  	if (err < 0) {
> >  	
> >  		BUG_ON(err != -ECONNREFUSED); /* Shouldn't happen */
> > 
> > -		printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", 
audit_pid);
> > -		audit_log_lost("auditd disappeared\n");
> > -		audit_pid = 0;
> > +		if (audit_pid) {
> > +			printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", 
audit_pid);
> > +			audit_log_lost("auditd disappeared\n");
> > +			audit_pid = 0;
> > +		}
> > 
> >  		/* we might get lucky and get this in the next auditd */
> >  		audit_hold_skb(skb);
> >  	
> >  	} else
> 
> --
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