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Date: Thu, 5 Aug 2010 13:21:18 -0400 (EDT)
From: "Todd Lipcon (JIRA)" <jira@apache.org>
To: mapreduce-issues@hadoop.apache.org
Subject: [jira] Commented: (MAPREDUCE-1994) Linux task-controller determines
 its own path insecurely
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    [ https://issues.apache.org/jira/browse/MAPREDUCE-1994?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12895743#action_12895743 ] 

Todd Lipcon commented on MAPREDUCE-1994:
----------------------------------------

Yea, sorry, HADOOP_CONF_DIR - the code is a bit messy as it actually detects HADOOP_HOME and then appends conf/ later... working on a patch that cleans this code up as well.

bq. It is documented to set permissions on task-controller to be as strict as "6050 root mapred". That should avoid creating hard links to the binary, no?

I believe you're allowed to make hard links to other files regardless of their permissions. If it were kept in a directory with strict permissions, that would help the issue a little bit.

bq. Just curious, an example of argv[0] spoof?

perl -e 'exec { "/real/path/to/task-controller" } "fake-argv[0]", "normal", "args", "...";'

There isn't really an obvious exploit here since task-controller is supposed to be set with permissions so that the normal user can't run it. But if it's misconfigured, the attacker can likely evade the check for that misconfiguration by something like this, so it's worth fixing.

> Linux task-controller determines its own path insecurely
> --------------------------------------------------------
>
>                 Key: MAPREDUCE-1994
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-1994
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: security, task-controller
>    Affects Versions: 0.22.0
>            Reporter: Todd Lipcon
>            Assignee: Todd Lipcon
>            Priority: Critical
>
> The task-controller uses argv[0] to determine its own path, and then calls stat() on that. Instead it should stat("/proc/self/exe") directly. This is important since argv[0] can be spoofed to point to another program and thus either fool the autodetection of HADOOP_HOME or evade various permissions checks.

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