[PATCH] Audit: netlink socket can be auto-bound to pid other than current->pid

[Eric Paris]

On 3/19/08, Pavel Emelyanov <xemul at openvz.org> wrote:
> Eric Paris wrote:
>  > On 3/18/08, Pavel Emelyanov <xemul at openvz.org> wrote:
>  >
>  > Can we please just leave audit_pid as the one flag to tell us if
>  > auditd is supposedly up there in userspace?  Use audit_nlk_pid to send
>  > messages to the right place, but leave everything else to do with
>  > audit_pid alone.
>
>
> OK, point taken ;) Is that patch looks OK? If yes, I'll comment
>  it properly and re-send to Andrew.
>
>  The audit_nlk_pid reset to 0 is not required, since all the
>  decisions are taken based on audit_pid value only.

I looks good to me.  Feel free to add Acked-by: Eric Paris
<eparis at redhat.com> on your submission.

-Eric

>
>  Signed-off-by: Pavel Emelyanov <xemul at openvz.org>
>
>
>  diff --git a/kernel/audit.c b/kernel/audit.c
>
> index ccc7d0e..12a0278 100644
>
> --- a/kernel/audit.c
>  +++ b/kernel/audit.c
>
> @@ -77,9 +77,13 @@ static int   audit_default;
>
>  /* If auditing cannot proceed, audit_failure selects what happens. */
>   static int     audit_failure = AUDIT_FAIL_PRINTK;
>
>  -/* If audit records are to be written to the netlink socket, audit_pid
>
> - * contains the (non-zero) pid. */
>  +/*
>  + * If audit records are to be written to the netlink socket, audit_pid
>  + * contains the pid of the auditd process and audit_nlk_pid contains
>  + * the pid to use to send netlink messages to that process.
>  + */
>   int            audit_pid;
>
> +static int     audit_nlk_pid;
>
>
>  /* If audit_rate_limit is non-zero, limit the rate of sending audit records
>
>   * to that number per second.  This prevents DoS attacks, but results in
>  @@ -349,7 +353,7 @@ static int kauditd_thread(void *dummy)
>
>                 wake_up(&audit_backlog_wait);
>                 if (skb) {
>                         if (audit_pid) {
>  -                               int err = netlink_unicast(audit_sock, skb, audit_pid, 0);
>
> +                               int err = netlink_unicast(audit_sock, skb, audit_nlk_pid, 0);
>
>                                 if (err < 0) {
>                                         BUG_ON(err != -ECONNREFUSED); /* Shoudn't happen */
>                                         printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", audit_pid);
>
> @@ -626,6 +630,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
>
>                                                         sid, 1);
>
>                         audit_pid = new_pid;
>  +                       audit_nlk_pid = NETLINK_CB(skb).pid;
>                 }
>                 if (status_get->mask & AUDIT_STATUS_RATE_LIMIT)
>                         err = audit_set_rate_limit(status_get->rate_limit,
>