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https://issues.apache.org/jira/browse/HADOOP-9758?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13724928#comment-13724928
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Andrew Wang commented on HADOOP-9758:
-------------------------------------
Newest patch removes Configurable from FileContext, and sets a final
{{resolveSymlinks}} boolean in FC.
I'm still not convinced that we can't make FileContext Configurable. There
isn't an AbstractFileSystem cache, and FileSystem makes it work even though
it's Configurable and has a cache. This is why I left FileSystem and
FileSystemLinkResolver as-is; clients might try to toggle symlink resolution on
and off via {{setConf()}}.
Anyway, not a big deal. Reviews appreciated :)
> Provide configuration option for FileSystem/FileContext symlink resolution
> --------------------------------------------------------------------------
>
> Key: HADOOP-9758
> URL: https://issues.apache.org/jira/browse/HADOOP-9758
> Project: Hadoop Common
> Issue Type: Improvement
> Affects Versions: 3.0.0, 2.3.0
> Reporter: Andrew Wang
> Assignee: Andrew Wang
> Attachments: hadoop-9758-4.patch, hdfs-4968-1.patch,
> hdfs-4968-2.patch, hdfs-4968-3.patch
>
>
> With FileSystem symlink support incoming in HADOOP-8040, some clients will
> wish to not transparently resolve symlinks. This is somewhat similar to
> O_NOFOLLOW in open(2).
> Rationale for is for a security model where a user can invoke a third-party
> service running as a service user to operate on the user's data. For
> instance, users might want to use Hive to query data in their homedirs, where
> Hive runs as the Hive user and the data is readable by the Hive user. This
> leads to a security issue with symlinks:
> # User Mallory invokes Hive to process data files in {{/user/mallory/hive/}}
> # Hive checks permissions on the files in {{/user/mallory/hive/}} and allows
> the query to proceed.
> # RACE: Mallory replaces the files in {{/user/mallory/hive}} with symlinks
> that point to user Ann's Hive files in {{/user/ann/hive}}. These files aren't
> readable by Mallory, but she can create whatever symlinks she wants in her
> own scratch directory.
> # Hive's MR jobs happily resolve the symlinks and accesses Ann's private data.
> This is also potentially useful for clients using FileContext, so let's add
> it there too.
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