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https://issues.apache.org/jira/browse/YARN-7590?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16275300#comment-16275300
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Eric Yang commented on YARN-7590:
---------------------------------
[~miklos.szeg...@cloudera.com] One problem with option 3 is that container
executor only knows about yarn gid, not uid. Is it sufficient to check against
{{yarn.nodemanager.linux-container-executor.group}} to determine if the prefix
directory is trusted? The answer is probably not because Hadoop configuration
directory could be set to hadoop group, which is the same group as
{{yarn.nodemanager.linux-container-executor.group}}.
Conversely, we can introduce another parameter in container-executor.cfg to
identify yarn uid for validating the prefix directory must owned by yarn uid.
Are we ok with this change?
> Improve container-executor validation check
> -------------------------------------------
>
> Key: YARN-7590
> URL: https://issues.apache.org/jira/browse/YARN-7590
> Project: Hadoop YARN
> Issue Type: Improvement
> Components: security, yarn
> Affects Versions: 2.0.1-alpha, 2.2.0, 2.3.0, 2.4.0, 2.5.0, 2.6.0, 2.7.0,
> 2.8.0, 2.8.1, 3.0.0-beta1
> Reporter: Eric Yang
>
> There is minimum check for prefix path for container-executor. If YARN is
> compromised, attacker can use container-executor to change system files
> ownership:
> {code}
> /usr/local/hadoop/bin/container-executor spark yarn 0 etc /home/yarn/tokens
> /home/spark / ls
> {code}
> This will change /etc to be owned by spark user:
> {code}
> # ls -ld /etc
> drwxr-s---. 110 spark hadoop 8192 Nov 21 20:00 /etc
> {code}
> Spark user can rewrite /etc files to gain more access. We can improve this
> with additional check in container-executor:
> # Make sure the prefix path is same as the one in yarn-site.xml, and
> yarn-site.xml is owned by root, 644, and marked as final in property.
> # Make sure the user path is not a symlink, usercache is not a symlink.
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