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