I'm guessing that your filesystem is not labeled at all.
You can relabel your entire system by doing touch /.autorelabel and then rebooting or by running fixfiles relabel and then rebooting
That should get the labeling done on the boot up.
You may want to go get a cup of coffee, it will likely take a while (say, 10-20 minutes).
[The 'chcon' is failing because the SELinux label for /var/log/boot.log look something like: 'system_u:object_r:var_log_t'. You were only providing the last component ...]
tom