Unable to execute a simple "whoami" unix command using java program on the server

Question

Im facing this strange issue of not being able to execute a simple "whoami" unix command on a AIX server. I have a webapplication that is deployed on an AIX server. Now I want to see under which WAS user my webapplication is currently running. So I added the below code:

    public String whoami() throws Exception {
        Process p = Runtime.getRuntime().exec("whoami");
        BufferedReader in = new BufferedReader(new InputStreamReader(p.getInputStream()));
        String line;
        String output = "";

        while ((line = in.readLine()) != null) {
            //System.out.println(line);
            output += line;
        }
        in.close();
        p.destroy();
        return output;
    }
}

The above code is added in a jar file which is referred by a JSP. The JSP has to receive the output of the code above and it displays the WAS User name. But when i deploy the webapplication on the server and try to observe the output, im getting an error message like

Error 500: access denied (java.io.FilePermission <> execute)

However, When I remove the above code and run my webapplication, everything runs fine. What wron am i doing here. Did I miss doing anything? Please help. This is the first time im working on UNIX

Alnitak · Accepted Answer · 2012-08-21 08:18:22Z

3

It looks like your web server has been configured with a Java security policy that prohibits executing external applications.

See http://java.sun.com/developer/onlineTraining/Programming/JDCBook/appA.html for information about Java Security Policies, and the documentation for your web server.

You will need to supply (or edit) a policy file to contain something like:

grant {
  permission java.io.FilePermission 
    "/usr/bin/whoami", "execute";
};

edited Aug 21, 2012 at 8:18

answered Aug 21, 2012 at 8:09

Alnitak

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9 Comments

Surya Chandra Over a year ago

I guess this might be the actual issue. Will check this and see. Thanks for your answer

Alnitak Over a year ago

@SuryaChandra the error message you posted is completely consistent with a restricted security policy.

Surya Chandra Over a year ago

I see the following entries in the was.policy file grant codeBase "file:${application}" { }; grant codeBase "file:${jars}" { }; grant codeBase "file:${connectorComponent}" { }; grant codeBase "file:${webComponent}" { }; grant codeBase "file:${ejbComponent}" { }; Does the above imply that currently there are no access permissions for anything?

Alnitak Over a year ago

@SuryaChandra That seems to be the WebSphere default. See pic.dhe.ibm.com/infocenter/wasinfo/v6r0/… for info on which one of the five might be most appropriate to add the required permission. Looks like either file:${application} or file:${webComponent} to me.

Surya Chandra Over a year ago

I think you were right. I will make the changes and see. Unfortunately, the server im working is down, I will update my observations soon

|

Mark Bramnik · Accepted Answer · 2012-08-21 06:56:23Z

2

Just out of curiosity Have you considered to use:

user.name

System property in Java?

answered Aug 21, 2012 at 6:56

Mark Bramnik

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Comments

Hachi · Accepted Answer · 2012-08-21 06:57:28Z

0

AFAIK whoami is a shell command and Runtime#exec() executes programs only.

you can try Runtime.getRuntime().exec(new String[]{"sh","-c","whoami"}) to call sh and let it execute whoami

another thing: do you need to destroy the process after reading?

answered Aug 21, 2012 at 6:57

Hachi

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1 Comment

Martijn Courteaux Over a year ago

Well, it is an actual program, it is located in /usr/bin. Martijn-Pro:~ martijncourteaux$ which whoami returns /usr/bin/whoami

Alex K · Accepted Answer · 2012-08-21 08:07:00Z

0

You can use the ProcessBuilder class instead of getRuntime().exec("whoami").

Here is sample code

import java.io.*;
import java.util.*;

public class DoProcessBuilder {

    public static void main(String args[]) throws IOException {
        if (args.length <= 0) {
            System.err.println("Need command to run");
            System.exit(-1);
        }
        Process process = new ProcessBuilder(args).start();
        InputStream is = process.getInputStream();
        InputStreamReader isr = new InputStreamReader(is);
        BufferedReader br = new BufferedReader(isr);
        String line;
        System.out.printf("Output of running &#37;s is:", Arrays.toString(args));
        while ((line = br.readLine()) != null) {
            System.out.println(line);
        }
    }
}

edited Aug 21, 2012 at 8:07

Alex K

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answered Aug 21, 2012 at 7:31

Jaydeep Rajput

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1 Comment

Alnitak Over a year ago

a ProcessBuilder should be restricted to the same security policies as Runtime.exec

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