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<title>Berkeley DB Reference Guide: Security</title>
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<td><dl><dt>Berkeley DB Reference Guide:<dd>Environment</dl></td>
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Security
The following are security issues that should be considered when writing
Berkeley DB applications:
 
Database environment permissions<ul compact><li>The directory used as the Berkeley DB database environment should have its
permissions set to ensure that files in the environment are not accessible
to users without appropriate permissions. Applications that add to the
user's permissions (for example, UNIX setuid or setgid applications),
must be carefully checked to not permit illegal use of those permissions
such as general file access in the environment directory.</ul>
Environment variables<ul compact><li>Setting the <a href="../../api_c/env_open.html#DB_USE_ENVIRON">DB_USE_ENVIRON</a> and <a href="../../api_c/env_open.html#DB_USE_ENVIRON_ROOT">DB_USE_ENVIRON_ROOT</a> flags
and allowing the use of environment variables during file naming can be
dangerous. Setting those flags in Berkeley DB applications with additional
permissions (for example, UNIX setuid or setgid applications) could
potentially allow users to read and write databases to which they would
not normally have access.</ul>
File permissions<ul compact><li>By default, Berkeley DB always creates files readable and writable by the owner
and the group (that is, S_IRUSR, S_IWUSR, S_IRGRP and S_IWGRP; or octal mode
0660 on historic UNIX systems). The group ownership of created files is
based on the system and directory defaults, and is not further specified
by Berkeley DB.</ul>
Temporary backing files<ul compact><li>If an unnamed database is created and the cache is too small to hold
the database in memory, Berkeley DB will create a temporary physical file to
enable it to page the database to disk as needed. In this case,
environment variables such as TMPDIR may be used to specify
the location of that temporary file. Although temporary backing files
are created readable and writable by the owner only (S_IRUSR and
S_IWUSR, or octal mode 0600 on historic UNIX systems), some filesystems
may not sufficiently protect temporary files created in random
directories from improper access. To be absolutely safe, applications
storing sensitive data in unnamed databases should use the
<a href="../../api_c/env_set_tmp_dir.html">DB_ENV-&gt;set_tmp_dir</a> method to specify a temporary directory with
known permissions.</ul>
Tcl API<ul compact><li>The Berkeley DB Tcl API does not attempt to avoid evaluating input as Tcl
commands. For this reason, it may be dangerous to pass unreviewed user
input through the Berkeley DB Tcl API, as the input may subsequently be
evaluated as a Tcl command. Additionally, the Berkeley DB Tcl API
initialization routine resets process' effective user and group IDs to
the real user and group IDs, to minimize the effectiveness of a Tcl
injection attack.</ul>
 
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