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- <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>21.6. Function Security</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets V1.79.1" /><link rel="prev" href="default-roles.html" title="21.5. Default Roles" /><link rel="next" href="managing-databases.html" title="Chapter 22. Managing Databases" /></head><body><div xmlns="http://www.w3.org/TR/xhtml1/transitional" class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">21.6. Function Security</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="default-roles.html" title="21.5. Default Roles">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="user-manag.html" title="Chapter 21. Database Roles">Up</a></td><th width="60%" align="center">Chapter 21. Database Roles</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 12.4 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="managing-databases.html" title="Chapter 22. Managing Databases">Next</a></td></tr></table><hr></hr></div><div class="sect1" id="PERM-FUNCTIONS"><div class="titlepage"><div><div><h2 class="title" style="clear: both">21.6. Function Security</h2></div></div></div><p>
- Functions, triggers and row-level security policies allow users to insert
- code into the backend server that other users might execute
- unintentionally. Hence, these mechanisms permit users to <span class="quote">“<span class="quote">Trojan
- horse</span>”</span> others with relative ease. The strongest protection is tight
- control over who can define objects. Where that is infeasible, write
- queries referring only to objects having trusted owners. Remove
- from <code class="varname">search_path</code> the public schema and any other schemas
- that permit untrusted users to create objects.
- </p><p>
- Functions run inside the backend
- server process with the operating system permissions of the
- database server daemon. If the programming language
- used for the function allows unchecked memory accesses, it is
- possible to change the server's internal data structures.
- Hence, among many other things, such functions can circumvent any
- system access controls. Function languages that allow such access
- are considered <span class="quote">“<span class="quote">untrusted</span>”</span>, and
- <span class="productname">PostgreSQL</span> allows only superusers to
- create functions written in those languages.
- </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="default-roles.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="user-manag.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="managing-databases.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">21.5. Default Roles </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 22. Managing Databases</td></tr></table></div></body></html>
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