8.3.5. Searching For and Viewing Denials
This section assumes the setroubleshoot, setroubleshoot-server, dbus and audit packages are installed, and that the
auditd, rsyslogd, and setroubleshootd daemons are running. Refer to Section 5.2, “Which Log File is Used” for information about starting these daemons. A number of tools are available for searching for and viewing SELinux denials, such as ausearch, aureport, and sealert.
ausearch
The audit package provides the
ausearch utility. From the ausearch(8) manual page: "ausearch is a tool that can query the audit daemon logs for events based on different search criteria"[13]. The ausearch utility accesses /var/log/audit/audit.log, and as such, must be run as the Linux root user:
| Searching For | Command |
|---|---|
| all denials | ausearch -m avc |
| denials for that today | ausearch -m avc -ts today |
| denials from the last 10 minutes | ausearch -m avc -ts recent |
To search for SELinux denials for a particular service, use the
-c comm-name option, where comm-name "is the executable’s name"[14], for example, httpd for the Apache HTTP Server, and smbd for Samba:
~]# ausearch -m avc -c httpd~]# ausearch -m avc -c smbd
With each
ausearch command, it is advised to use either the --interpret (-i) option for easier readability, or the --raw (-r) option for script processing. Refer to the ausearch(8) manual page for further ausearch options.
aureport
The audit package provides the
aureport utility. From the aureport(8) manual page: "aureport is a tool that produces summary reports of the audit system logs"[15]. The aureport utility accesses /var/log/audit/audit.log, and as such, must be run as the Linux root user. To view a list of SELinux denials and how often each one occurred, run the aureport -a command. The following is example output that includes two denials:
~]# aureport -a
AVC Report
========================================================
# date time comm subj syscall class permission obj event
========================================================
1. 05/01/2009 21:41:39 httpd unconfined_u:system_r:httpd_t:s0 195 file getattr system_u:object_r:samba_share_t:s0 denied 2
2. 05/03/2009 22:00:25 vsftpd unconfined_u:system_r:ftpd_t:s0 5 file read unconfined_u:object_r:cifs_t:s0 denied 4
Refer to the aureport(8) manual page for further
aureport options.
sealert
The setroubleshoot-server package provides the
sealert utility, which reads denial messages translated by setroubleshoot-server. Denials are assigned IDs, as seen in /var/log/messages. The following is an example denial from messages:
setroubleshoot: SELinux is preventing /usr/sbin/httpd from name_bind access on the tcp_socket. For complete SELinux messages. run sealert -l 8c123656-5dda-4e5d-8791-9e3bd03786b7
In this example, the denial ID is
8c123656-5dda-4e5d-8791-9e3bd03786b7. The -l option takes an ID as an argument. Running the sealert -l 8c123656-5dda-4e5d-8791-9e3bd03786b7 command presents a detailed analysis of why SELinux denied access, and a possible solution for allowing access.
If you are running the X Window System, have the setroubleshoot and setroubleshoot-server packages installed, and the
setroubleshootd, dbus and auditd daemons are running, a warning is displayed when access is denied by SELinux:
Clicking on
Show launches the sealert GUI, which allows you to troubleshoot the problem:
Alternatively, run the
sealert -b command to launch the sealert GUI. To view a detailed analysis of all denial messages, run the sealert -l \* command.
See the sealert(8) manual page for further
sealert options.
[13]
From the ausearch(8) manual page, as shipped with the audit package in Red Hat Enterprise Linux 6.
[14]
From the ausearch(8) manual page, as shipped with the audit package in Red Hat Enterprise Linux 6.
[15]
From the aureport(8) manual page, as shipped with the audit package in Red Hat Enterprise Linux 6.
