Re: [PATCH 2/2] audit: log binding and unbinding to netlink multicast
On Wed, Nov 30, 2016 at 2:26 PM, Steve Grubb <sgrubb(a)redhat.com> wrote:
Log information about programs connecting and disconnecting to the
audit
netlink multicast socket. This is needed so that during investigations a
security officer can tell who or what had access to the audit trail. This
helps to meet the FAU_SAR.2 requirement for Common Criteria.
Signed-off-by: sgrubb <sgrubb(a)redhat.com>
---
include/uapi/linux/audit.h | 1 +
kernel/audit.c | 31 +++++++++++++++++++++++++++----
2 files changed, 28 insertions(+), 4 deletions(-)
This needs an associated test for the audit-testsuite and a RFE page
on the wiki. I also created a GH issue since this is a CC issue and
something we want to track progress on, link below:
* https://github.com/linux-audit/audit-kernel/issues/28
Some more specific comments below ...
diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
index 82e8aa5..e6dd046 100644
--- a/include/uapi/linux/audit.h
+++ b/include/uapi/linux/audit.h
@@ -111,6 +111,7 @@
#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 unanswerd */
+#define AUDIT_EVENT_LISTENER 1330 /* Task joined multicast read socket */
#define AUDIT_AVC 1400 /* SE Linux avc denial or grant */
#define AUDIT_SELINUX_ERR 1401 /* Internal SE Linux Errors */
diff --git a/kernel/audit.c b/kernel/audit.c
index 22f8c3d..910a7c1 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -1161,22 +1161,45 @@ void audit_log_task_simple(struct audit_buffer *ab,
struct task_struct *tsk)
}
EXPORT_SYMBOL(audit_log_task_simple);
+/* Log information about who is connecting to the audit multicast socket */
+static void audit_log_multicast_bind(int group, const char *op, int err)
+{
A bit of a nit, but it seems odd to call this "..._bind" when we use
it to log both bind and unbind events, maybe "..._op"/"..._status" or
something?
+ struct audit_buffer *ab;
+
+ ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_EVENT_LISTENER);
+ if (!ab)
+ return;
+
+ audit_log_task_simple(ab, current);
Right now the only call to audit_log_task_simple() is the one above
and I'm not a fan of merging code like that, just open code
audit_log_task_simple() in the function above. If you need similar
functionality for use by other functions in the future you can
reintroduce audit_log_task_simple().
+ audit_log_format(ab, " nlnk-grp=%d op=%s res=%d",
group, op, !err);
+ audit_log_end(ab);
+}
+
/* Run custom bind function on netlink socket group connect or bind requests.
*/
-static int audit_bind(struct net *net, int group)
+static int audit_multicast_bind(struct net *net, int group)
{
+ int err = 0;
+
if (!capable(CAP_AUDIT_READ))
- return -EPERM;
+ err = -EPERM;
+ audit_log_multicast_bind(group, "connect", err);
- return 0;
+ return err;
+}
+
+static void audit_multicast_unbind(struct net *net, int group)
+{
+ audit_log_multicast_bind(group, "disconnect", 0);
}
static int __net_init audit_net_init(struct net *net)
{
struct netlink_kernel_cfg cfg = {
.input = audit_receive,
- .bind = audit_bind,
+ .bind = audit_multicast_bind,
.flags = NL_CFG_F_NONROOT_RECV,
.groups = AUDIT_NLGRP_MAX,
+ .unbind = audit_multicast_unbind,
};
struct audit_net *aunet = net_generic(net, audit_net_id);
--
2.7.4
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--
paul moore
www.paul-moore.com