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<th>Priority</th>
<td>medium
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<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - CAP_SYS_MODULE cannot be dropped at boot"
href="https://bugs.freedesktop.org/show_bug.cgi?id=68434">68434</a>
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<th>Assignee</th>
<td>systemd-bugs@lists.freedesktop.org
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<th>Summary</th>
<td>CAP_SYS_MODULE cannot be dropped at boot
</td>
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<th>QA Contact</th>
<td>systemd-bugs@lists.freedesktop.org
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Classification</th>
<td>Unclassified
</td>
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<th>OS</th>
<td>Linux (All)
</td>
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<th>Reporter</th>
<td>matteo.sasso@gmail.com
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<th>Hardware</th>
<td>All
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<th>Status</th>
<td>NEW
</td>
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<th>Version</th>
<td>unspecified
</td>
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<th>Component</th>
<td>general
</td>
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<th>Product</th>
<td>systemd
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<p>
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<pre>At boot, init drops its own capabilities and usermode helpers' according to the
CapabilityBoundingSet option in systemd/system.conf. Unfortunately, to modify
files in /proc/sys/kernel/usermodehelper you need CAP_SYS_MODULE: if you don't
include CAP_SYS_MODULE in the bounding set, boot fails with "Failed to drop
capability bounding set of usermode helpers".
I think being able to drop CAP_SYS_MODULE is one of the most useful uses of
that option. To fix this, capabilities should be dropped in reverse order:
first those of usermodehelper, then those of systemd's init.
It should be a trivial change to main.c (just search for the error message and
you'll see what I mean).</pre>
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