I want to stop droping the logs into audit_hold_queue when the auditd is abnormal.it seems that this modification goes against the design intent of audit_hold_queue. its effect is similar to removing the audit_hold_queue. diff --git a/kernel/audit.c b/kernel/audit.c index 2a38cbaf3ddb..a8091b1a6587 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -748,6 +748,7 @@ static int kauditd_send_queue(struct sock *sk, u32 portid, (*err_hook)(skb); if (rc == -EAGAIN) rc = 0; + audit_default = AUDIT_OFF; /* continue to drain the queue */ continue; } else @@ -755,6 +756,7 @@ static int kauditd_send_queue(struct sock *sk, u32 portid, } else { /* skb sent - drop the extra reference and continue */ consume_skb(skb); + audit_default = audit_enabled; failed = 0; } }

在 2022/1/13 23:22, Paul Moore 写道: > On Thu, Jan 13, 2022 at 6:57 AM cuigaosheng <cuigaosheng1(a)huawei.com&gt; wrote: >> When we add "audit=1" to the cmdline, kauditd will take up 100% >> cpu resource.As follows: >> >> configurations: >> auditctl -b 64 >> auditctl --backlog_wait_time 60000 >> auditctl -r 0 >> auditctl -w /root/aaa -p wrx >> shell scripts： >> #!/bin/bash >> i=0 >> while [ $i -le 66 ] >> do >> touch /root/aaa >> let i++ >> done >> mandatory conditions: >> >> add "audit=1" to the cmdline, and kill -19 pid_number(for /sbin/auditd). >> >> As long as we keep the audit_hold_queue non-empty, flush the hold queue will fall into >> an infinite loop. >> >> 713 static int kauditd_send_queue(struct sock *sk, u32 portid, >> 714 struct sk_buff_head *queue, >> 715 unsigned int retry_limit, >> 716 void (*skb_hook)(struct sk_buff *skb), >> 717 void (*err_hook)(struct sk_buff *skb)) >> 718 { >> 719 int rc = 0; >> 720 struct sk_buff *skb; >> 721 unsigned int failed = 0; >> 722 >> 723 /* NOTE: kauditd_thread takes care of all our locking, we just use >> 724 * the netlink info passed to us (e.g. sk and portid) */ >> 725 >> 726 while ((skb = skb_dequeue(queue))) { >> 727 /* call the skb_hook for each skb we touch */ >> 728 if (skb_hook) >> 729 (*skb_hook)(skb); >> 730 >> 731 /* can we send to anyone via unicast? */ >> 732 if (!sk) { >> 733 if (err_hook) >> 734 (*err_hook)(skb); >> 735 continue; >> 736 } >> 737 >> 738 retry: >> 739 /* grab an extra skb reference in case of error */ >> 740 skb_get(skb); >> 741 rc = netlink_unicast(sk, skb, portid, 0); >> 742 if (rc < 0) { >> 743 /* send failed - try a few times unless fatal error */ >> 744 if (++failed >= retry_limit || >> 745 rc == -ECONNREFUSED || rc == -EPERM) { >> 746 sk = NULL; >> 747 if (err_hook) >> 748 (*err_hook)(skb); >> 749 if (rc == -EAGAIN) >> 750 rc = 0; >> 751 /* continue to drain the queue */ >> 752 continue; >> 753 } else >> 754 goto retry; >> 755 } else { >> 756 /* skb sent - drop the extra reference and continue */ >> 757 consume_skb(skb); >> 758 failed = 0; >> 759 } >> 760 } >> 761 >> 762 return (rc >= 0 ? 0 : rc); >> 763 } >> >> When kauditd attempt to flush the hold queue, the queue parameter is &audit_hold_queue, >> and if netlink_unicast(line 741 ) return -EAGAIN, sk will be NULL(line 746), so err_hook(kauditd_rehold_skb) >> will be call. Then continue, skb_dequeue(line 726) and err_hook(kauditd_rehold_skb,line 733) will >> fall into an infinite loop. >> I don't really understand the value of audit_hold_queue, can we remove it, or stop droping the logs >> into kauditd_rehold_skb when the auditd is abnormal? > Thanks Gaosheng for the bug report, I'm able to reproduce this and I'm > looking into it now. I'll report back when I have a better idea of > the problem and a potential fix. >