From 9b1938a59a146ddd8f7a3a0f541a0955229c1b02 Mon Sep 17 00:00:00 2001 From: Brian Goff Date: Tue, 6 Oct 2020 19:40:30 +0000 Subject: [PATCH] [PATCH] Do not set DOCKER_TMP to be owned by remapped root The remapped root does not need access to this dir. Having this owned by the remapped root opens the host up to an uprivileged user on the host being able to escalate privileges. While it would not be normal for the remapped UID to be used outside of the container context, it could happen. Signed-off-by: Brian Goff (cherry picked from commit bfedd2725971303efb7a2fe5d6990317b381622f) Signed-off-by: Tibor Vass Gbp-Pq: Name cve-2021-21284-2.patch --- engine/daemon/daemon.go | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/engine/daemon/daemon.go b/engine/daemon/daemon.go index c2887ce0..be4e8d5d 100644 --- a/engine/daemon/daemon.go +++ b/engine/daemon/daemon.go @@ -676,7 +676,7 @@ func NewDaemon(ctx context.Context, config *config.Config, pluginStore *plugin.S } // set up the tmpDir to use a canonical path - tmp, err := prepareTempDir(config.Root, rootIDs) + tmp, err := prepareTempDir(config.Root) if err != nil { return nil, fmt.Errorf("Unable to get the TempDir under %s: %s", config.Root, err) } @@ -1209,7 +1209,7 @@ func (daemon *Daemon) Subnets() ([]net.IPNet, []net.IPNet) { // prepareTempDir prepares and returns the default directory to use // for temporary files. // If it doesn't exist, it is created. If it exists, its content is removed. -func prepareTempDir(rootDir string, rootIdentity idtools.Identity) (string, error) { +func prepareTempDir(rootDir string) (string, error) { var tmpDir string if tmpDir = os.Getenv("DOCKER_TMPDIR"); tmpDir == "" { tmpDir = filepath.Join(rootDir, "tmp") @@ -1227,9 +1227,7 @@ func prepareTempDir(rootDir string, rootIdentity idtools.Identity) (string, erro } } } - // We don't remove the content of tmpdir if it's not the default, - // it may hold things that do not belong to us. - return tmpDir, idtools.MkdirAllAndChown(tmpDir, 0700, rootIdentity) + return tmpDir, idtools.MkdirAllAndChown(tmpDir, 0700, idtools.CurrentIdentity()) } func (daemon *Daemon) setGenericResources(conf *config.Config) error { -- 2.30.2