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From "Allen Wittenauer (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-13079) dfs -ls -q prints non-printable characters
Date Thu, 05 May 2016 13:56:13 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-13079?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15272403#comment-15272403

Allen Wittenauer commented on HADOOP-13079:

bq. The fact that one component has a security bug 

It's not a security bug for the reasons you think it's a security bug.  After all, wc, find,
du, ... tons of other UNIX commands will happily print out terminal escape sequences with
no option to turn them off.  It is, however, problematic for traditional ftpd implementations
since it's a great way to inject buffer overflows and then get root on a remote server.

bq. "Should the filename be able use control characters to hijack the admin's GNU screen session
and execute arbitrary code? I would say no, what do you say?"

... and my answer is the same as it was almost a decade ago, in some HDFS JIRA somewhere,
where a related topic came up before: HDFS would be better served by having a limit on what
consists of a legal file and directory name.  With an unlimited namespace, it's impossible
to test against and impossible to protect every scenario in which oddball characters show
up.  What's legal in one locale may not be legal in another. 

bq. However, it is not constructive to -1 a patch fixing a security vulnerability without
suggesting an alternate way of fixing that vulnerability. 

Again: this is not fixing a security vulnerability.

bq.  If this stays unfixed, it will probably get a CVE number.

Speaking of, have you located a CVE for GNU ls yet? I mean, if this 'ls printing terminal
control characters' is a security problem, surely there would be a CVE for it and du and wc
and ...

Also, are you prepared to file a CVE for *every* *single* *time* Hadoop prints out a directory
or file name to the screen?  There are probably hundreds if not thousands of places, obvious
ones like 'fs -count' and less obvious ones like 'yarn logs'.  This is a 'tilting at windmills'
problem.  It is MUCH better to have ls blow up than be taken by surprise by something else
later on.

> dfs -ls -q prints non-printable characters
> ------------------------------------------
>                 Key: HADOOP-13079
>                 URL: https://issues.apache.org/jira/browse/HADOOP-13079
>             Project: Hadoop Common
>          Issue Type: Bug
>    Affects Versions: 2.6.0
>            Reporter: John Zhuge
>            Assignee: John Zhuge
> Add option {{-q}} to "hdfs dfs -ls" to print non-printable characters as "?". Non-printable
characters are defined by [isprint(3)|http://linux.die.net/man/3/isprint] according to the
current locale.
> Default to {{-q}} behavior on terminal; otherwise, print raw characters. See the difference
in these 2 command lines:
> * {{hadoop fs -ls /dir}}
> * {{hadoop fs -ls /dir | od -c}}
> In C, {{isatty(STDOUT_FILENO)}} is used to find out whether the output is a terminal.
Since Java doesn't have {{isatty}}, I will use JNI to call C {{isatty()}} because the closest
test {{System.console() == null}} does not work in some cases.

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