[PATCH ghak90 V9 04/13] audit: log drop of contid on exit of last task

[Richard Guy Briggs <rgb@xxxxxxxxxx>]

Since we are tracking the life of each audit container indentifier, we
can match the creation event with the destruction event.  Log the
destruction of the audit container identifier when the last process in
that container exits.

Signed-off-by: Richard Guy Briggs <rgb@xxxxxxxxxx>
---
 kernel/audit.c   | 20 ++++++++++++++++++++
 kernel/audit.h   |  2 ++
 kernel/auditsc.c |  2 ++
 3 files changed, 24 insertions(+)

diff --git a/kernel/audit.c b/kernel/audit.c
index 6d387793f702..9e0b38ce1ead 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -2558,6 +2558,26 @@ int audit_set_contid(struct task_struct *task, u64 contid)
 	return rc;
 }
 
+void audit_log_container_drop(void)
+{
+	struct audit_buffer *ab;
+	struct audit_contobj *cont;
+
+	rcu_read_lock();
+	cont = _audit_contobj_get(current);
+	_audit_contobj_put(cont);
+	if (!cont || refcount_read(&cont->refcount) > 1)
+		goto out;
+	ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_CONTAINER_OP);
+	if (!ab)
+		goto out;
+	audit_log_format(ab, "op=drop opid=%d contid=%llu old-contid=%llu",
+			 task_tgid_nr(current), cont->id, cont->id);
+	audit_log_end(ab);
+out:
+	rcu_read_unlock();
+}
+
 /**
  * audit_log_end - end one audit record
  * @ab: the audit_buffer
diff --git a/kernel/audit.h b/kernel/audit.h
index 182fc76ea276..d07093903008 100644
--- a/kernel/audit.h
+++ b/kernel/audit.h
@@ -254,6 +254,8 @@ extern void audit_log_d_path_exe(struct audit_buffer *ab,
 extern struct tty_struct *audit_get_tty(void);
 extern void audit_put_tty(struct tty_struct *tty);
 
+extern void audit_log_container_drop(void);
+
 /* audit watch/mark/tree functions */
 #ifdef CONFIG_AUDITSYSCALL
 extern unsigned int audit_serial(void);
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index f00c1da587ea..f03d3eb0752c 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1575,6 +1575,8 @@ static void audit_log_exit(void)
 
 	audit_log_proctitle();
 
+	audit_log_container_drop();
+
 	/* Send end of event record to help user space know we are finished */
 	ab = audit_log_start(context, GFP_KERNEL, AUDIT_EOE);
 	if (ab)
-- 
1.8.3.1