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<p class="MsoNormal"><span style="color:#1F497D">Here are the notes from the non-root presentation that we did last week.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">TODO: send doc patches. (AI: Michael)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Phosphor-systemd bbclass – ties together these steps. Need more info here.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Add snippet to add udev rule for group ownership.<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Overall:<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Every daemon should run as its own user<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Use common group ownership to control access to files that must be accessed by multiple daemons<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Usually don’t need to use ACLs, if you think you need them, probably should rethink things<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Use group owner on /dev/ entries to control which daemons can open which hardware<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Udev usually has “reasonable” ownership groups that you can use. Slightly prefer just using those unless they are grossly inappropriate. (less work)<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Use udev rule addons to adjust group/owner for dev entries if absolutely necessary<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>For network listening daemons: use the systemd port units to let systemd listen for you. (systemd socket activation)<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Use systemd-tmpfiles to set up runtime paths with the correct permissions<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Use useradd-staticids bbclass to add users<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Code:<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>“most” code doesn’t need to change. Except for daemons that do interesting things like listen on network ports. Use socket activation there<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Use systemd bus activation for dbus services, where possible<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Use systemd to specify user to run as, where possible. This means that your code can’t have any vulnerabilities before you drop root because it’s never root.<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Use systemd daemon model (don’t fork). Makes debugging easier.<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>System calls that are likely to fail when you switch from root to non-root: open(), access()<span style="color:#1F497D">, stat()</span><o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:1.25in;text-indent:-.25in;mso-list:l0 level2 lfo2">
<![if !supportLists]><span style="font-family:"Courier New""><span style="mso-list:Ignore">o<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]>Grep for open and variants to prep<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Implementation<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Run service from command line: strace –o /tmp/output.txt –f /path/to/service –service-options<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Look through output.txt to see failing system calls<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Putting it in the build:<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Add user in recipe<o:p></o:p></p>
<p class="MsoNormal"># users and group for the Policy Daemons<o:p></o:p></p>
<p class="MsoNormal">GROUPADD_PARAM_${PN} = " -o -g 974 policy "<o:p></o:p></p>
<p class="MsoNormal">USERADD_PARAM_${PN} = "-u 987 -M -s /bin/false -o -g policy policyd"<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Update systemd service file<o:p></o:p></p>
<p class="MsoNormal">User=policyd<o:p></o:p></p>
<p class="MsoNormal">Group=policyd<o:p></o:p></p>
<p class="MsoNormal">SupplementaryGroups=foo bar baz<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Add systemd-tmpfiles<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Add udev rules if necessary<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>PROFIT<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Project ideas:<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Non-root working group?<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Requirements for all new daemons to be non-root before acceptance?<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:.75in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Remediation ideas for current code? <o:p></o:p></p>
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