Nothing prevents a new auditd starting up and replacing a valid
audit_pid when an old auditd is still running, effectively starving out
the old auditd since audit_pid no longer points to the old valid auditd.
There isn't an easy way to detect if an old auditd is still running on
the existing audit_pid other than attempting to send a message to see if
it fails. If no message to auditd has been attempted since auditd died
unnaturally or got killed, audit_pid will still indicate it is alive.
Signed-off-by: Richard Guy Briggs <r...@redhat.com>
---
Note: Would it be too bold to actually block the registration of a new
auditd if the netlink_getsockbyportid() call succeeded? Would other
checks be appropriate?
kernel/audit.c | 5 +++++
1 files changed, 5 insertions(+), 0 deletions(-)
diff --git a/kernel/audit.c b/kernel/audit.c
index 18cdfe2..1fa1e0d 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -872,6 +872,11 @@ static int audit_receive_msg(struct sk_buff *skb, struct
nlmsghdr *nlh)
if (s.mask & AUDIT_STATUS_PID) {
int new_pid = s.pid;
+ if (audit_pid && new_pid &&
+ !IS_ERR(netlink_getsockbyportid(audit_sock,
audit_nlk_portid)))
+ pr_warn("auditd replaced by new auditd before
normal shutdown: "
+ "(old)audit_pid=%d (by)pid=%d
new_pid=%d",
+ audit_pid, pid, new_pid);
if ((!new_pid) && (task_tgid_vnr(current) != audit_pid))
return -EACCES;
if (audit_enabled != AUDIT_OFF)
--
1.7.1
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