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1<?xml version="1.0" encoding="UTF-8" standalone="no"?>2<!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>22.6. 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 Vsnapshot" /><link rel="prev" href="predefined-roles.html" title="22.5. Predefined Roles" /><link rel="next" href="managing-databases.html" title="Chapter 23. Managing Databases" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">22.6. Function Security</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="predefined-roles.html" title="22.5. Predefined Roles">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="user-manag.html" title="Chapter 22. Database Roles">Up</a></td><th width="60%" align="center">Chapter 22. Database Roles</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 16.3 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="managing-databases.html" title="Chapter 23. Managing Databases">Next</a></td></tr></table><hr /></div><div class="sect1" id="PERM-FUNCTIONS"><div class="titlepage"><div><div><h2 class="title" style="clear: both">22.6. Function Security <a href="#PERM-FUNCTIONS" class="id_link">#</a></h2></div></div></div><p>3   Functions, triggers and row-level security policies allow users to insert4   code into the backend server that other users might execute5   unintentionally. Hence, these mechanisms permit users to <span class="quote">“<span class="quote">Trojan6   horse</span>”</span> others with relative ease. The strongest protection is tight7   control over who can define objects. Where that is infeasible, write8   queries referring only to objects having trusted owners.  Remove9   from <code class="varname">search_path</code> any schemas that permit untrusted users10   to create objects.11  </p><p>12   Functions run inside the backend13   server process with the operating system permissions of the14   database server daemon.  If the programming language15   used for the function allows unchecked memory accesses, it is16   possible to change the server's internal data structures.17   Hence, among many other things, such functions can circumvent any18   system access controls.  Function languages that allow such access19   are considered <span class="quote">“<span class="quote">untrusted</span>”</span>, and20   <span class="productname">PostgreSQL</span> allows only superusers to21   create functions written in those languages.22  </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="predefined-roles.html" title="22.5. Predefined Roles">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="user-manag.html" title="Chapter 22. Database Roles">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="managing-databases.html" title="Chapter 23. Managing Databases">Next</a></td></tr><tr><td width="40%" align="left" valign="top">22.5. Predefined Roles </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 16.3 Documentation">Home</a></td><td width="40%" align="right" valign="top"> Chapter 23. Managing Databases</td></tr></table></div></body></html>