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<base href="https://bugs.freedesktop.org/" />
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<body><table border="1" cellspacing="0" cellpadding="8">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - drop_privileges fails with -EPERM"
href="https://bugs.freedesktop.org/show_bug.cgi?id=88898">88898</a>
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</tr>
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<th>Summary</th>
<td>drop_privileges fails with -EPERM
</td>
</tr>
<tr>
<th>Product</th>
<td>systemd
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</td>
</tr>
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<th>Hardware</th>
<td>Other
</td>
</tr>
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<th>OS</th>
<td>All
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>medium
</td>
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<th>Component</th>
<td>general
</td>
</tr>
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<th>Assignee</th>
<td>systemd-bugs@lists.freedesktop.org
</td>
</tr>
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<th>Reporter</th>
<td>mustrumr97@gmail.com
</td>
</tr>
<tr>
<th>QA Contact</th>
<td>systemd-bugs@lists.freedesktop.org
</td>
</tr></table>
<p>
<div>
<pre>systemd-resolved fails to start:
Failed to drop capabilities: Operation not permitted
Broken in f11943c53ec181829a821c6b27acf828bab71caa.
Drop all capabilities:
1. prctl(PR_SET_KEEPCAPS, keep_capabilities != 0) // 0 when we drop all
capabilities
2. setresuid() // bye bye capabilities
3. Add CAP_SETPCAP // fails because we have no capabilities
4. Reduce capability bounding set
5. Drop capabilities
6. prctl(PR_SET_KEEPCAPS, 0)
Capabilites should always be kept after setresuid() so that the capability
bounding set can be reduced.
--- a/src/shared/capability.c
+++ b/src/shared/capability.c
@@ -249,7 +249,7 @@ int drop_privileges(uid_t uid, gid_t gid, uint64_t
keep_capabilities) {
return log_error_errno(errno, "Failed to drop auxiliary groups
list: %m");
/* Ensure we keep the permitted caps across the setresuid(), if we
need them */
- if (prctl(PR_SET_KEEPCAPS, keep_capabilities != 0) < 0)
+ if (prctl(PR_SET_KEEPCAPS, 1) < 0)
return log_error_errno(errno, "Failed to enable keep
capabilities flag: %m");
r = setresuid(uid, uid, uid);</pre>
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