Logrotation 权限问题

Question

我认为我的一台 Ubuntu 服务器上的日志文件有点乱，需要一些建议和方法来解决它。当日志轮换发生时，我看到很多这样的错误：

error: failed to rename /var/log/dovecot.log to /var/log/dovecot.log.1: Permission denied
error: failed to rename /var/log/mail.err to /var/log/mail.err.1: Permission denied
error: failed to rename /var/log/mail.log to /var/log/mail.log.1: Permission denied
error: failed to rename /var/log/owncloud.log to /var/log/owncloud.log.1: Permission denied
error: error renaming /var/log/syslog.5 to /var/log/syslog.6: Permission denied
error: error renaming /var/log/amavis.log.3 to /var/log/amavis.log.4: Permission denied
error: error renaming /var/log/auth.log.3 to /var/log/auth.log.4: Permission denied
error: error renaming /var/log/nginx/access.log.6 to /var/log/nginx/access.log.7: Permission denied
error: error renaming /var/log/nginx/error.log.8 to /var/log/nginx/error.log.9: Permission denied
error: error renaming /var/log/kern.log.3 to /var/log/kern.log.4: Permission denied

我的 logrotate 配置内容 (/etc/logrotate.conf.daily)

daily

rotate 3
missingok
su root syslog

include /etc/logrotate.d/daily

/etc/loggrotate.daily/syslog.daily 下的 syslog logrotation 配置是

/var/log/syslog {
        su root syslog
        rotate 5
        missingok
        postrotate
                invoke-rc.d rsyslog rotate > /dev/null
        endscript
        create 644 root syslog
}

我现在的问题是：

1. 根/var/log目录应该具有什么权限？目前它有 drwxr-xr-x 12 root syslog 4.0K Mar 19 11:48 log 什么问题吗？

2. 有什么技巧或命令可以让我找出每个日志文件所需的权限？例如 dovecot.log，要设置哪些用户/组/文件权限？这适用于上述所有日志文件。

非常感谢