[SOLVED] How to grant Tomcat 9 access on other files

Issue

Tomcat 9 is sandboxed.

I want to read data of a log file.

The file is in "/opt/zigbee2mqtt/data/."

I read this thread already and tried it. How to allow Tomcat war app to write in folder

I edited the file, and did systemctl daemon-reload as well as systemctl restart tomcat9.

Then I wrote my java class with should read the data out of the log file. But I get an exception.

java.io.FileNotFoundException: /opt/zigbee2mqtt/data/configuration.yaml (Permission denied)
        at java.base/java.io.FileOutputStream.open0(Native Method)
        at java.base/java.io.FileOutputStream.open(FileOutputStream.java:298)
        at java.base/java.io.FileOutputStream.<init>(FileOutputStream.java:237)
        at java.base/java.io.FileOutputStream.<init>(FileOutputStream.java:187)
        at com.fasterxml.jackson.dataformat.yaml.YAMLFactory.createGenerator(YAMLFactory.java:437)
        at com.fasterxml.jackson.databind.ObjectMapper.createGenerator(ObjectMapper.java:1156)
        at com.fasterxml.jackson.databind.ObjectMapper.writeValue(ObjectMapper.java:3570)
        at zigbee.main.doupdateconfiguration(main.java:81)
        at Servlet.configuration.doPost(configuration.java:72)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:660)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.apache.catalina.filters.ExpiresFilter.doFilter(ExpiresFilter.java:1226)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:200)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
        at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:668)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
        at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408)
        at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
        at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:834)
        at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1415)
        at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
        at java.base/java.lang.Thread.run(Thread.java:834)

I think if I change something with chmod or chown, but maybe the Zigbee service won't work? I am not the Linux expert. I don't want to do anything wrong or insecure.

root@raspberrypi:/opt/zigbee2mqtt/data# ls -halt
total 24K
drwxr-xr-x  6 pi pi 4.0K May 12 09:17 log
drwxr-xr-x  3 pi pi 4.0K May 10 18:31 .
-rw-r--r--  1 pi pi 4.0K May 10 18:31 database.db
-rw-rw-r--  1 pi pi  360 May 10 18:31 state.json
-rw-rw-r--  1 pi pi  330 May 10 17:23 configuration.yaml
drwxr--r-- 12 pi pi 4.0K May 10 11:16 ..

What would be the best solution that Tomcat 9 can read the file and Zigbee can update it either?

Update:

root@raspberrypi:/opt/zigbee2mqtt/data# ll
total 24K
-rw-rw-r--  1 pi webservice  360 May 13 22:03 state.json
drwxrw-r-x  6 pi webservice 4.0K May 12 09:17 log
drwxr-xr-x  3 pi pi         4.0K May 10 18:31 .
-rw-rw-r--  1 pi webservice 4.0K May 10 18:31 database.db
-rw-rw-r--  1 pi webservice  330 May 10 17:23 configuration.yaml
drwxr--r-- 12 pi pi         4.0K May 10 11:16 ..
root@raspberrypi:/opt/zigbee2mqtt/data# id tomcat
uid=1001(tomcat) gid=1001(tomcat) groups=1001(tomcat),1002(webservice)

Extraxt of: /etc/systemd/system/tomcat9.service.d/override.conf

[Service]
ReadWritePaths=/usr/local/jakarta-tomcat/webapps/smartzig/_x_logs/
ReadWritePaths=/opt/zigbee2mqtt/data/
ReadWritePaths=/opt/zigbee2mqtt/
ReadWritePaths=/opt/

Solution

Add the tomcat to a group and grant this group the required access to that files, i.g. you can create a group called webserver. Then restart tomcat and try again.

---

Steps

$ sudo groupadd webserver

$ sudo usermod -a -G webserver tomcat9

$ sudo chgrp webserver configuration.yaml

$ sudo chmod g=rw configuration.yaml

$ sudo systemctl restart tomcat9

, Update the group ownership of the directories (that contains the files) by adding the permissions to it

$ sudo chgrp webserver /opt/zigbee2mqtt/data/
$ sudo chgrp webserver /opt/zigbee2mqtt/ 

$ sudo chmod g=rwx /opt/zigbee2mqtt/data/
$ sudo chmod g=rwx /opt/zigbee2mqtt/

Answered By - heaprc

Answer Checked By - Mildred Charles (WPSolving Admin)