Red Hat Bugzilla – Bug 1007663
selinux AVC when mgetty tries to open log file
Last modified: 2013-10-14 13:21:50 EDT
Description of problem: I'm using mgetty to monitor a usb modem /dev/ttyACM0 over caller id information in Fedora 19 x86_64 after update to these rpms: selinux-policy-3.12.1-74.2.fc19.noarch selinux-policy-devel-3.12.1-74.2.fc19.noarch selinux-policy-targeted-3.12.1-74.2.fc19.noarch the following selinux is generated: type=AVC msg=audit(1378997528.877:20510): avc: denied { open } for pid=2278 comm="mgetty" path="/var/log/mgetty.ttyACM0.log" dev="md114" ino=137 scontext=system_u:system_r:getty_t:s0 tcontext=system_u:object_r:var_log_t:s0 tclass=file the log file name /var/log/mgetty.ttyACM0.log is created automatically by the mgetty process and according to man 8 mgetty DIAGNOSTICS section shows: If mgetty doesn't work the way it should, the main source of diagnostic data is the log file. It can be found in "/var/log/mgetty.ttyxx.log" the /etc/selinux/targeted/contexts/files/file_contexts shows a regex of: /var/log/mgetty\.log.* -- system_u:object_r:getty_log_t:s0 but it don't apply to "/var/log/mgetty.ttyACM0.log" I executed: semanage fcontext -a --seuser system_u -t getty_log_t '/var/log/mgetty.*\.log.*' restorecon -RFv /var/log/mgetty.ttyACM0.log and that fixed the AVC Version-Release number of selected component (if applicable): selinux-policy-3.12.1-74.2.fc19.noarch selinux-policy-devel-3.12.1-74.2.fc19.noarch selinux-policy-targeted-3.12.1-74.2.fc19.noarch thanks in advance, Gabriel
This looks like the log file is being created by some other process other then getty_t? If getty_t process creates a file in /var/log it will be labeled getty_log_t according to policy. Any chance the init script is creating this file?
systemctl stop mgetty@ttyACM0.service3s I will remove the local selinux rule semanage fcontext -d --seuser system_u -t getty_log_t '/var/log/mgetty.*\.log.*' and the log cd /var/log/ mv mgetty.ttyACM0.log mgetty.ttyACM0.log.old cd /tmp systemctl start mgetty@ttyACM0.service cd /var/log ls -Zlh /var/log/mgetty.ttyACM0.log* -rw-r--r--. 1 system_u:object_r:getty_log_t:s0 root root 1.9K Sep 16 20:34 /var/log/mgetty.ttyACM0.log -rw-r--r--. 1 system_u:object_r:getty_log_t:s0 root root 112K Sep 15 03:46 /var/log/mgetty.ttyACM0.log.1 -rw-r--r--. 1 system_u:object_r:getty_log_t:s0 root root 108K Sep 8 04:02 /var/log/mgetty.ttyACM0.log.2 -rw-r--r--. 1 system_u:object_r:getty_log_t:s0 root root 94K Sep 1 04:40 /var/log/mgetty.ttyACM0.log.3 -rw-r--r--. 1 system_u:object_r:getty_log_t:s0 root root 32K Sep 16 20:27 /var/log/mgetty.ttyACM0.log.old and Dan you are right the file is created correctly now, the avc appeared after updating the selinux-policy but before rebooting the machine so at that time I tried restorecon -RFv /var/log/mgetty* but the file contexts didn't change so reported the bug, maybe I needed to reboot the machine first before report the AVC so I'm closing the bug thanks, and thanks for your work in selinux, in earlier Fedora realases I have many custom allow selinux rules but now only have one Gabriel
I updated to: selinux-policy-3.12.1-74.4.fc19.noarch selinux-policy-devel-3.12.1-74.4.fc19.noarch selinux-policy-targeted-3.12.1-74.4.fc19.noarch and that triggered the bug because the update reset the log file context to: ls -lZ /var/log/mgetty.ttyACM0.log* -rw-r--r--. root root system_u:object_r:var_log_t:s0 /var/log/mgetty.ttyACM0.log -rw-r--r--. root root system_u:object_r:var_log_t:s0 /var/log/mgetty.ttyACM0.log.1 -rw-r--r--. root root system_u:object_r:var_log_t:s0 /var/log/mgetty.ttyACM0.log.2 if I remove the /var/log/mgetty.ttyACM0.log and start systemctl start mgetty@ttyACM0.service the log file is created correctly ls -lZ /var/log/mgetty.ttyACM0.log* -rw-r--r--. root root system_u:object_r:getty_log_t:s0 /var/log/mgetty.ttyACM0.log -rw-r--r--. root root system_u:object_r:var_log_t:s0 /var/log/mgetty.ttyACM0.log.1 but if I do restorecon -RFv /var/log/mgetty.ttyACM0.log* restorecon reset /var/log/mgetty.ttyACM0.log context system_u:object_r:getty_log_t:s0->system_u:object_r:var_log_t:s0 thanks, Gabriel
commit 5daf31839f67b838ee23c91847b4d0b4bd70de4e Author: Miroslav Grepl <mgrepl@redhat.com> Date: Mon Sep 30 16:17:29 2013 +0200 Fix labeling for mgetty.* logs
selinux-policy-3.12.1-74.9.fc19 has been submitted as an update for Fedora 19. https://admin.fedoraproject.org/updates/selinux-policy-3.12.1-74.9.fc19
Package selinux-policy-3.12.1-74.9.fc19: * should fix your issue, * was pushed to the Fedora 19 testing repository, * should be available at your local mirror within two days. Update it with: # su -c 'yum update --enablerepo=updates-testing selinux-policy-3.12.1-74.9.fc19' as soon as you are able to. Please go to the following url: https://admin.fedoraproject.org/updates/FEDORA-2013-18701/selinux-policy-3.12.1-74.9.fc19 then log in and leave karma (feedback).
selinux-policy-3.12.1-74.9.fc19 has been pushed to the Fedora 19 stable repository. If problems still persist, please make note of it in this bug report.