8a0d82c468
- Update CVE-2019-19921 patch to match upstream PR. * CVE-2019-19921.patch OBS-URL: https://build.opensuse.org/request/show/765103 OBS-URL: https://build.opensuse.org/package/show/Virtualization:containers/runc?expand=0&rev=86
49 lines
1.8 KiB
Diff
49 lines
1.8 KiB
Diff
From 3291d66b98445bd7f7d02eac7f2bca2ac2c56942 Mon Sep 17 00:00:00 2001
|
|
From: Aleksa Sarai <asarai@suse.de>
|
|
Date: Sat, 21 Dec 2019 23:40:17 +1100
|
|
Subject: [PATCH] rootfs: do not permit /proc mounts to non-directories
|
|
|
|
mount(2) will blindly follow symlinks, which is a problem because it
|
|
allows a malicious container to trick runc into mounting /proc to an
|
|
entirely different location (and thus within the attacker's control for
|
|
a rename-exchange attack).
|
|
|
|
This is just a hotfix (to "stop the bleeding"), and the more complete
|
|
fix would be finish libpathrs and port runc to it (to avoid these types
|
|
of attacks entirely, and defend against a variety of other /proc-related
|
|
attacks). It can be bypased by someone having "/" be a volume controlled
|
|
by another container.
|
|
|
|
Fixes: CVE-2019-19921
|
|
Signed-off-by: Aleksa Sarai <asarai@suse.de>
|
|
---
|
|
libcontainer/rootfs_linux.go | 12 ++++++++++++
|
|
1 file changed, 12 insertions(+)
|
|
|
|
diff --git a/libcontainer/rootfs_linux.go b/libcontainer/rootfs_linux.go
|
|
index 291021440a1a..106c4c2b98bf 100644
|
|
--- a/libcontainer/rootfs_linux.go
|
|
+++ b/libcontainer/rootfs_linux.go
|
|
@@ -299,6 +299,18 @@ func mountToRootfs(m *configs.Mount, rootfs, mountLabel string, enableCgroupns b
|
|
|
|
switch m.Device {
|
|
case "proc", "sysfs":
|
|
+ // If the destination already exists and is not a directory, we bail
|
|
+ // out This is to avoid mounting through a symlink or similar -- which
|
|
+ // has been a "fun" attack scenario in the past.
|
|
+ // TODO: This won't be necessary once we switch to libpathrs and we can
|
|
+ // stop all of these symlink-exchange attacks.
|
|
+ if fi, err := os.Lstat(dest); err != nil {
|
|
+ if !os.IsNotExist(err) {
|
|
+ return err
|
|
+ }
|
|
+ } else if fi.Mode()&os.ModeDir == 0 {
|
|
+ return fmt.Errorf("filesystem %q must be mounted on ordinary directory", m.Device)
|
|
+ }
|
|
if err := os.MkdirAll(dest, 0755); err != nil {
|
|
return err
|
|
}
|
|
--
|
|
2.24.1
|
|
|