add backport-0004-CVE-2021-41133.patch.

backport-0004-CVE-2021-41133.patch

@@ -0,0 +1,42 @@
+From a10f52a7565c549612c92b8e736a6698a53db330 Mon Sep 17 00:00:00 2001
+From: Simon McVittie <smcv@collabora.com>
+Date: Wed, 1 Sep 2021 11:59:00 +0100
+Subject: [PATCH] run: Block clone3() in sandbox
+
+clone3() can be used to implement clone() with CLONE_NEWUSER, allowing
+a sandboxed process to get CAP_SYS_ADMIN in a new namespace and
+manipulate its root directory. We need to block this so that AF_UNIX-based
+socket servers (X11, Wayland, etc.) can rely on
+/proc/PID/root/.flatpak-info existing for all Flatpak-sandboxed apps.
+
+Partially fixes GHSA-67h7-w3jq-vh4q.
+
+Thanks: an anonymous reporter
+Signed-off-by: Simon McVittie <smcv@collabora.com>
+
+Conflict:NA
+Reference:https://github.com/flatpak/flatpak/commit/a10f52a7565c549612c92b8e736a6698a53db330
+
+---
+ common/flatpak-run.c | 6 ++++++
+ 1 file changed, 6 insertions(+)
+
+diff --git a/common/flatpak-run.c b/common/flatpak-run.c
+index 5cf6d2e..dad0cfe 100644
+--- a/common/flatpak-run.c
++++ b/common/flatpak-run.c
+@@ -2832,6 +2832,12 @@ setup_seccomp (FlatpakBwrap   *bwrap,
+ 
+     /* Don't allow faking input to the controlling tty (CVE-2017-5226) */
+     {SCMP_SYS (ioctl), EPERM, &SCMP_A1 (SCMP_CMP_MASKED_EQ, 0xFFFFFFFFu, (int) TIOCSTI)},
++
++    /* seccomp can't look into clone3()'s struct clone_args to check whether
++     * the flags are OK, so we have no choice but to block clone3().
++     * Return ENOSYS so user-space will fall back to clone().
++     * (GHSA-67h7-w3jq-vh4q; see also https://github.com/moby/moby/commit/9f6b562d) */
++    {SCMP_SYS (clone3), ENOSYS},
+   };
+ 
+   struct
+-- 
+2.27.0