[PATCH 3/3] audit: drop audit_cmd_lock in AUDIT_USER family of cases

Richard Guy Briggs
2013-12-05T02:45:56Z

We do not need to hold the audit_cmd_mutex for this family of cases. The
possible exception to this is the call to audit_filter_user(), so drop the lock
immediately after. To help in fixing the race we are trying to avoid, make
sure that nothing called by audit_filter_user() calls audit_log_start(). In
particular, watch out for *_audit_rule_match().

This fix will take care of systemd and anything USING audit. It still means
that we could race with something configuring audit and auditd shutting down.

Signed-off-by: Richard Guy Briggs <rgb@tricolour.ca>
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
---
kernel/audit.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/kernel/audit.c b/kernel/audit.c
index 4689012..4cbc945 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -713,6 +713,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
if (err)
break;
}
+ mutex_unlock(&audit_cmd_mutex);
audit_log_common_recv_msg(&ab, msg_type);
if (msg_type != AUDIT_USER_TTY)
audit_log_format(ab, " msg='%.1024s'",
@@ -729,6 +730,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
}
audit_set_pid(ab, NETLINK_CB(skb).portid);
audit_log_end(ab);
+ mutex_lock(&audit_cmd_mutex);
}
break;
case AUDIT_ADD_RULE:
--
1.7.1