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
.
The audit package provides ausearch
. From the ausearch(8) manual page: "ausearch
is a tool that can query the audit daemon logs based for events based on different search criteria"[]. The ausearch
tool accesses /var/log/audit/audit.log
, and as such, must be run as the Linux root user:
Searching For |
Command |
all denials |
/sbin/ausearch -m avc |
denials for that today |
/sbin/ausearch -m avc -ts today |
denials from the last 10 minutes |
/sbin/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"[], for example, httpd
for the Apache HTTP Server, and smbd
for Samba:
/sbin/ausearch -m avc -c httpd
/sbin/ausearch -m avc -c smbd
Refer to the ausearch(8) manual page for further ausearch
options.
The audit package provides aureport
. From the aureport(8) manual page: "aureport
is a tool that produces summary reports of the audit system logs"[]. The aureport
tool 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:
# /sbin/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.
The setroubleshoot-server package provides sealert
, 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 httpd (httpd_t) "getattr" to /var/www/html/file1 (samba_share_t). For complete SELinux messages. run sealert -l 84e0b04d-d0ad-4347-8317-22e74f6cd020
In this example, the denial ID is 84e0b04d-d0ad-4347-8317-22e74f6cd020
. The -l
option takes an ID as an argument. Running the sealert -l 84e0b04d-d0ad-4347-8317-22e74f6cd020
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, and displays denials in HTML output:
-
Run the sealert -b
command to launch the sealert
GUI.
-
Run the sealert -l \*
command to view a detailed analysis of all denials.
-
As the Linux root user, run the sealert -a /var/log/audit/audit.log -H > audit.html
command to create a HTML version of the sealert
analysis, as seen with the sealert
GUI.
Refer to the sealert(8) manual page for further sealert
options.