From aacfed4b0b4fa8997705e4a5fbbd3d5cde3523e0 Mon Sep 17 00:00:00 2001
From: Simon McVittie <smcv@collabora.com>
Date: Wed, 1 Sep 2021 14:19:31 +0100
Subject: [PATCH] run: Block setns()

If we don't allow unshare() or clone() with CLONE_NEWUSER, we also
shouldn't allow joining an existing (but different) namespace.

Partially fixes GHSA-67h7-w3jq-vh4q.

Signed-off-by: Simon McVittie <smcv@collabora.com>
---
 common/flatpak-run.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/common/flatpak-run.c b/common/flatpak-run.c
index 1307856fa..ce9c7cb75 100644
--- a/common/flatpak-run.c
+++ b/common/flatpak-run.c
@@ -2823,6 +2823,7 @@ setup_seccomp (FlatpakBwrap   *bwrap,
 
     /* Don't allow subnamespace setups: */
     {SCMP_SYS (unshare), EPERM},
+    {SCMP_SYS (setns), EPERM},
     {SCMP_SYS (mount), EPERM},
     {SCMP_SYS (pivot_root), EPERM},
 #if defined(__s390__) || defined(__s390x__) || defined(__CRIS__)