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Copyright (C) 2001-2015 Free Software Foundation, Inc.\\
Copyright (C) 2001-2015 Nikos Mavrogiannopoulos
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<title>GnuTLS 3.4.8: Running in a sandbox</title>
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<a name="Running-in-a-sandbox"></a>
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<p>
Next: <a href="Sessions-and-fork.html#Sessions-and-fork" accesskey="n" rel="next">Sessions and fork</a>, Previous: <a href="Thread-safety.html#Thread-safety" accesskey="p" rel="prev">Thread safety</a>, Up: <a href="Introduction-to-the-library.html#Introduction-to-the-library" accesskey="u" rel="up">Introduction to the library</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Function-and-Data-Index.html#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<a name="Running-in-a-sandbox-1"></a>
<h4 class="subsection">6.1.6 Running in a sandbox</h4>
<a name="index-seccomp"></a>
<a name="index-isolated-mode"></a>
<p>Given that TLS protocol handling as well as X.509 certificate
parsing are complicated processes involving several thousands lines of code,
it is often desirable (and recommended) to run the TLS session handling in
a sandbox like seccomp. That has to be allowed by the overall software design,
but if available, it adds an additional layer of protection by
preventing parsing errors from becoming vessels for further security issues such
as code execution.
</p>
<p>GnuTLS requires the following system calls to be available for its proper
operation.
</p>
<ul>
<li> nanosleep
</li><li> time
</li><li> gettimeofday
</li><li> clock_gettime
</li><li> getrusage
</li><li> send
</li><li> recv
</li><li> writev
</li><li> read (to read from /dev/urandom)
</li><li> getrandom (this is Linux-kernel specific)
</li><li> select
</li></ul>
<p>As well as an calls needed for memory allocation to work. Note however, that GnuTLS
depends on libc for the system calls, and there is no guarrantee that libc will
call the expected system call. For that it is recommended to test your
program in all the targetted platforms when filters like seccomp are in place.
</p>
<p>An example with a seccomp filter from GnuTLS’ test suite is at:
<a href="http://gitlab.com/gnutls/gnutls/blob/master/tests/seccomp.c">http://gitlab.com/gnutls/gnutls/blob/master/tests/seccomp.c</a>.
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