Apparmor 拒绝 ntpd 访问其自己的日志

Question

ntpd 抱怨它无法访问自己的日志

# ntpd -qgddd 
...
11 Sep 16:23:00 ntpd[7262]: can't open /var/log/ntpstats/peerstats.20130911: Permission denied
...
11 Sep 16:23:01 ntpd[7262]: can't open /var/log/ntpstats/peerstats.20130911: Permission denied
...
11 Sep 16:23:01 ntpd[7262]: can't open /var/log/ntpstats/loopstats.20130911: Permission denied

strace 表示同意

open("/var/log/ntpstats/loopstats.20130911", O_WRONLY|O_CREAT|O_APPEND, 0666) = -1 EACCES (Permission denied)

根据 syslog apparmor 阻止它这样做

[526597.819210] type=1400 audit(1378909374.692:91): apparmor="DENIED" operation="open" parent=1013 profile="/usr/sbin/ntpd" name="/usr/local/sbin/" pid=7262 comm="ntpd" requested_mask="r" denied_mask="r" fsuid=0 ouid=0
[526597.819277] type=1400 audit(1378909374.692:92): apparmor="DENIED" operation="open" parent=1013 profile="/usr/sbin/ntpd" name="/usr/local/bin/" pid=7262 comm="ntpd" requested_mask="r" denied_mask="r" fsuid=0 ouid=0
[526597.819330] type=1400 audit(1378909374.692:93): apparmor="DENIED" operation="open" parent=1013 profile="/usr/sbin/ntpd" name="/usr/sbin/" pid=7262 comm="ntpd" requested_mask="r" denied_mask="r" fsuid=0 ouid=0
[526597.819383] type=1400 audit(1378909374.692:94): apparmor="DENIED" operation="open" parent=1013 profile="/usr/sbin/ntpd" name="/usr/bin/" pid=7262 comm="ntpd" requested_mask="r" denied_mask="r" fsuid=0 ouid=0
[526597.819434] type=1400 audit(1378909374.692:95): apparmor="DENIED" operation="open" parent=1013 profile="/usr/sbin/ntpd" name="/sbin/" pid=7262 comm="ntpd" requested_mask="r" denied_mask="r" fsuid=0 ouid=0
[526597.819485] type=1400 audit(1378909374.692:96): apparmor="DENIED" operation="open" parent=1013 profile="/usr/sbin/ntpd" name="/bin/" pid=7262 comm="ntpd" requested_mask="r" denied_mask="r" fsuid=0 ouid=0
[526597.819541] type=1400 audit(1378909374.692:97): apparmor="DENIED" operation="open" parent=1013 profile="/usr/sbin/ntpd" name="/usr/bin/" pid=7262 comm="ntpd" requested_mask="r" denied_mask="r" fsuid=0 ouid=0

即使在 ntp 的个人资料中明确允许

# less /etc/apparmor.d/usr.sbin.ntpd
...
/var/log/ntpstats/clockstats* rwl,
/var/log/ntpstats/loopstats*  rwl,
/var/log/ntpstats/peerstats*  rwl,
/var/log/ntpstats/rawstats*   rwl,
/var/log/ntpstats/sysstats*   rwl,

发生什么了？

这是一个带有 3.8.0-30 通用内核的 Ubuntu Server 13.04。

Answer 1

该 apparmor 日志显示 ntpd 尝试访问（读取）目录，例如/usr/local/sbin/, /usr/sbin/ etc。它没有告诉任何有关ntpd被拒绝访问的信息/var/log/ntpstats.

var/log/ntpstats请检查 /及其内容的常规 unix 权限。