[PATCH ghak90 V8 05/16] 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   | 17 +++++++++++++++++
 kernel/audit.h   |  2 ++
 kernel/auditsc.c |  2 ++
 3 files changed, 21 insertions(+)

diff --git a/kernel/audit.c b/kernel/audit.c
index 4bab20f5f781..fa8f1aa3a605 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -2502,6 +2502,23 @@ int audit_set_contid(struct task_struct *task, u64 contid)
 	return rc;
 }
 
+void audit_log_container_drop(void)
+{
+	struct audit_buffer *ab;
+
+	if (!current->audit || !current->audit->cont ||
+	    refcount_read(&current->audit->cont->refcount) > 1)
+		return;
+	ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_CONTAINER_OP);
+	if (!ab)
+		return;
+
+	audit_log_format(ab, "op=drop opid=%d contid=%llu old-contid=%llu",
+			 task_tgid_nr(current), audit_get_contid(current),
+			 audit_get_contid(current));
+	audit_log_end(ab);
+}
+
 /**
  * audit_log_end - end one audit record
  * @ab: the audit_buffer
diff --git a/kernel/audit.h b/kernel/audit.h
index e4a31aa92dfe..162de8366b32 100644
--- a/kernel/audit.h
+++ b/kernel/audit.h
@@ -255,6 +255,8 @@ 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 0e2d50533959..bd855794ad26 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1568,6 +1568,8 @@ 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