On 8/26/20 10:46 AM, Stephen Smalley wrote:
On Wed, Aug 26, 2020 at 10:35 AM Chris PeBenito
<chpebeni@xxxxxxxxxxxxxxxxxxx> wrote:
On 8/26/20 9:25 AM, Chris PeBenito wrote:
I was looking into this dbus-broker audit message, which has the wrong audit type:
audit[422]: USER_AVC pid=422 uid=999 auid=4294967295 ses=4294967295
subj=system_u:system_r:system_dbusd_t msg='avc: received policyload notice
(seqno=2)
This is due to dbus-broker setting their avc log callback to send USER_AVC audit
messages for everything that comes to the libselinux log callback. I think the
right thing to do there is to change it to emit USER_SELINUX_ERR audit messages
if the log message is SELINUX_ERROR, otherwise log the message using their
regular method (stderr I think).
But the question became, why is the userspace AVC not simply emitting its own
USER_MAC_POLICY_LOAD audit message instead of sending a message to the log
callback?
Ok, I missed that there is a SELINUX_AVC log type and that's how the userspace
denial messages are sent out. How about adding SELINUX_POLICYLOAD and
SELINUX_ENFORCE log types so that callers can emit appropriate audit messages?
Do we need two different new types or just one? Otherwise, I don't
have a problem with adding new ones as long as it doesn't break
existing applications.
Regarding the risk of breaking existing applications, I did some checking on
some userspace AVC users and what they do in their log callback:
* systemd only audits SELINUX_AVC and SELINUX_ERROR messages and ignores
others(as Petr noted)
* xorg-server audits SELINUX_AVC correctly but audits SELINUX_INFO as
USER_MAC_POLICY_LOAD and everything else it ignores the type and audits as
AUDIT_USER_SELINUX_ERR
* dbus-broker ignores type and audits everything as USER_AVC
* dbus-service ignores type and audits everything as USER AVC
* pam: pam_rootok ignores type and audits everything as USER_AVC
* sepgsql custom AVC implementation (this was news to me)
* shadow-utils only audits SELINUX_AVC and SELINUX_ERROR messages and others go
to syslog
* cronie: no callback set
That's all the ones I could think of. Which ones am I missing?
--
Chris PeBenito
