Re: [PATCH V3 1/2] audit: stop an old auditd being starved out by a new auditd

[Steve Grubb]

On Tuesday, December 22, 2015 09:24:56 AM Paul Moore wrote:
> On Tuesday, December 22, 2015 04:03:06 AM Richard Guy Briggs wrote:
> > Nothing prevents a new auditd starting up and replacing a valid
> > audit_pid when an old auditd is still running, effectively starving out
> > the old auditd since audit_pid no longer points to the old valid auditd.
> > 
> > If no message to auditd has been attempted since auditd died unnaturally
> > or got killed, audit_pid will still indicate it is alive.  There isn't
> > an easy way to detect if an old auditd is still running on the existing
> > audit_pid other than attempting to send a message to see if it fails.
> > An -ECONNREFUSED almost certainly means it disappeared and can be
> > replaced.  Other errors are not so straightforward and may indicate
> > transient problems that will resolve themselves and the old auditd will
> > recover.  Yet others will likely need manual intervention for which a
> > new auditd will not solve the problem.
> > 
> > Send a new message type (AUDIT_REPLACE) to the old auditd containing a
> > u32 with the PID of the new auditd.  If the audit replace message
> > succeeds (or doesn't fail with certainty), fail to register the new
> > auditd and return an error (-EEXIST).
> > 
> > This is expected to make the patch preventing an old auditd orphaning a
> > new auditd redundant.
> > 
> > V3: Switch audit message type from 1000 to 1300 block.
> > 
> > Signed-off-by: Richard Guy Briggs <rgb@xxxxxxxxxx>
> > ---
> > 
> >  include/uapi/linux/audit.h |    1 +
> >  kernel/audit.c             |   16 +++++++++++++++-
> >  2 files changed, 16 insertions(+), 1 deletions(-)
> > 
> > diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
> > index 843540c..d820aa9 100644
> > --- a/include/uapi/linux/audit.h
> > +++ b/include/uapi/linux/audit.h
> > @@ -110,6 +110,7 @@
> > 
> >  #define AUDIT_SECCOMP		1326	/* Secure Computing event */
> >  #define AUDIT_PROCTITLE		1327	/* Proctitle emit event */
> >  #define AUDIT_FEATURE_CHANGE	1328	/* audit log listing feature changes
> 
> */
> 
> > +#define AUDIT_REPLACE		1329	/* Replace auditd if this packet...
> 
> Steve, are you okay with this record number?

Yes. Just wondering what to do with the event.

-Steve
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