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<h2>TOMOYO Linux : FAQ</h2>

<h3><a name="general">General questions</a></h3>

<p><strong>Q1: What is TOMOYO Linux?</strong></p>
<p>A1: A Linux kernel that can both automatically and interactively generate policies for Mandatory Access Control.</p>
<p><strong>Q2: Who are the target users?</strong></p>
<p>A2: Administrators that do not have the time and energy for more complex server security management.</p>
<p><strong>Q3: How much extra memory is consumed?</strong></p>
<p>A3: Fixed part (code and data in the kernel) is about 100 KB, variant part (access permissions) is a few hundred KB.</p>
<p><strong>Q4: How large is the performance loss?</strong></p>
<p>A4: Not formally tested, but it should be negligible for the regular user.</p>
<p><strong>Q5: Which kernel versions are supported?</strong></p>
<p>A5: Linux kernel 2.4.37 is supported from the 2.4 tree, and Linux kernel 2.6.27 and later are supported from the 2.6 tree. These are available from <a href="https://www.kernel.org/">https://www.kernel.org/</a>.</p>
<p><strong>Q6: Is it possible to support patched kernels from distributors?</strong></p>
<p>A6: Yes, if you manually inserts hooks.</p>
<p><strong>Q7: What is TOMOYO Linux licensed under?</strong></p>
<p>A7: TOMOYO Linux is licensed under the GNU General Public License (GPL).</p>
<p><strong>Q8: Does TOMOYO Linux have any usage other than for Mandatory Access Control?</strong></p>
<p>A8: Yes, you can use it as a system analysis tool or to create custom filesystem images with minimum files.</p>

<h3><a name="management">Policy management</a></h3>
<p><strong>Q1: Is the policy syntax easy?</strong></p>
<p>A1: Yes, the syntax has been designed to be easily managed.</p>
<p><strong>Q2: What is a domain?</strong></p>
<p>A2: The domain in TOMOYO Linux is a history of process execution determined by the sequence in which they are executed.</p>
<p><strong>Q3: What is a profile?</strong></p>
<p>A3: The profile in TOMOYO Linux is a configuration that defines what level and type of MAC is used for a particular domain.</p>
<p><strong>Q4: Can I update policies dynamically?</strong></p>
<p>A4: Yes.</p>
<p><strong>Q5: Do I need to restart processes after updating policies?</strong></p>
<p>A5: No, unless you delete a domain and recreate it.</p>
<p><strong>Q6: Will processes referring a domain crash by deleting the domain?</strong></p>
<p>A6: No, processes will not crash because the deleted domain remains until processes terminate.</p>
<p><strong>Q7: What measures against tampering policies are there?</strong></p>
<p>A7: Programs or domains can be restricted from modifying policy.</p>
<p><strong>Q8: How can I edit policies?</strong></p>
<p>A8: An ncurses based CUI editor is included to modify policies. You may also use any text editors.</p>
<p><strong>Q9: What is "Learning mode"?</strong></p>
<p>A9: A mode in which access permissions are appended automatically in order to determine safe behaviours and resources that are required by a program for normal operation.</p>
<p><strong>Q10: Are there problems appending access permissions automatically?</strong></p>
<p>A10: There should be no problems, as TOMOYO Linux uses absolute pathnames and fine-grained domain divisions.</p>
<p><strong>Q11: Can I update packages while the Mandatory Access Control is enabled?</strong></p>
<p>A11: Yes, by assigning different profiles to domains, or by using tools provided with TOMOYO Linux (e.g. /usr/sbin/ccs-queryd).</p>
<p><strong>Q12: Can I protect only daemon processes like SELinux's Targeted Policy?</strong></p>
<p>A12: Yes, by assigning different profiles to domains.</p>

<h3><a name="implementation">Implementation</a></h3>
<p><strong>Q1: What is the security model of TOMOYO Linux?</strong></p>
<p>A1: Domain and Type Enforcement (DTE) only.</p>
<p><strong>Q2: Are there concepts of users and roles?</strong></p>
<p>A2: No, but it is possible to delegate a part of administration tasks.</p>
<p><strong>Q3: Do userland applications need to be patched?</strong></p>
<p>A3: No.</p>
<p><strong>Q4: Can TOMOYO Linux protect sshd from exploit codes?</strong></p>
<p>A4: No, but it is possible to countermeasure illegal logins by enforcing additional authentication.</p>
<p><strong>Q5: Which division is TOMOYO Linux categorized in TCSEC?</strong></p>
<p>A5: Unknown.</p>
<p><strong>Q6: What security labels does TOMOYO Linux use?</strong></p>
<p>A6: TOMOYO Linux uses absolute pathnames as security labels.</p>
<p><strong>Q7: Can I use wildcards for pathnames?</strong></p>
<p>A7: Yes.</p>
<p><strong>Q8: Is multi-level security (MLS) supported?</strong></p>
<p>A8: No. Save in the different directories according to sensitivity level of the file.</p>
<p><strong>Q9: Are there functions like Linux Intrustion Detection System's (LIDS) stateful ACL?</strong></p>
<p>A9: No.</p>
<p><strong>Q10: Are the correctness of security labels guaranteed?</strong></p>
<p>A10: Since pathnames are used as security labels, the correctness of security labels is guaranteed unless the directory entry get corrupted.</p>
<p><strong>Q11: Are resources other than files protected?</strong></p>
<p>A11: Yes, TOMOYO Linux supports many resources (e.g. network ports, signal transmissions, capabilities, environment variables). See <a href="http://tomoyo.sourceforge.jp/comparison.html.en">TOMOYO Linux functionality comparison table</a> for a list of all the resources that can be restricted.</p>
<p><strong>Q12: Is there a loadable kernel module version?</strong></p>
<p>A12: Yes. Although there are preconditions and limitations, a loadable kernel module version is available. See <a href="http://akari.sourceforge.jp/comparison.html.en">AKARI / TOMOYO functionality comparison table</a> for more information.</p>

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