From 5d1ec2960df41b15040534e6507932cc5cf83542 Mon Sep 17 00:00:00 2001
From: Daniel J Walsh <dwalsh@redhat.com>
Date: Fri, 5 Feb 2021 06:04:30 -0500
Subject: Do not reset storage when running inside of a container

Currently if the host shares container storage with a container
running podman, the podman inside of the container resets the
storage on the host. This can cause issues on the host, as
well as causes the podman command running the container, to
fail to unmount /dev/shm.

podman run -ti --rm --privileged -v /var/lib/containers:/var/lib/containers quay.io/podman/stable podman run alpine echo hello
	* unlinkat /var/lib/containers/storage/overlay-containers/a7f3c9deb0656f8de1d107e7ddff2d3c3c279c11c1635f233a0bffb16051fb2c/userdata/shm: device or resource busy
	* unlinkat /var/lib/containers/storage/overlay-containers/a7f3c9deb0656f8de1d107e7ddff2d3c3c279c11c1635f233a0bffb16051fb2c/userdata/shm: device or resource busy

Since podman is volume mounting in the graphroot, it will add a flag to
/run/.containerenv to tell podman inside of container whether to reset storage or not.

Since the inner podman is running inside of the container, no reason to assume this is a fresh reboot, so if "container" environment variable is set then skip
reset of storage.

Also added tests to make sure /run/.containerenv is runnig correctly.

Fixes: https://github.com/containers/podman/issues/9191

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>
---
 libpod/runtime.go | 37 ++++++++++++++++++++++++++++++++++---
 1 file changed, 34 insertions(+), 3 deletions(-)

(limited to 'libpod/runtime.go')

diff --git a/libpod/runtime.go b/libpod/runtime.go
index 42af2046d..c04d91b9d 100644
--- a/libpod/runtime.go
+++ b/libpod/runtime.go
@@ -1,6 +1,7 @@
 package libpod
 
 import (
+	"bufio"
 	"context"
 	"fmt"
 	"os"
@@ -26,6 +27,7 @@ import (
 	"github.com/containers/storage"
 	"github.com/cri-o/ocicni/pkg/ocicni"
 	"github.com/docker/docker/pkg/namesgenerator"
+	spec "github.com/opencontainers/runtime-spec/specs-go"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 )
@@ -622,9 +624,12 @@ func (r *Runtime) Shutdown(force bool) error {
 func (r *Runtime) refresh(alivePath string) error {
 	logrus.Debugf("Podman detected system restart - performing state refresh")
 
-	// First clear the state in the database
-	if err := r.state.Refresh(); err != nil {
-		return err
+	// Clear state of database if not running in container
+	if !graphRootMounted() {
+		// First clear the state in the database
+		if err := r.state.Refresh(); err != nil {
+			return err
+		}
 	}
 
 	// Next refresh the state of all containers to recreate dirs and
@@ -904,3 +909,29 @@ func (r *Runtime) getVolumePlugin(name string) (*plugin.VolumePlugin, error) {
 func (r *Runtime) GetSecretsStorageDir() string {
 	return filepath.Join(r.store.GraphRoot(), "secrets")
 }
+
+func graphRootMounted() bool {
+	f, err := os.OpenFile("/run/.containerenv", os.O_RDONLY, os.ModePerm)
+	if err != nil {
+		return false
+	}
+	defer f.Close()
+
+	scanner := bufio.NewScanner(f)
+	for scanner.Scan() {
+		if scanner.Text() == "graphRootMounted=1" {
+			return true
+		}
+	}
+	return false
+}
+
+func (r *Runtime) graphRootMountedFlag(mounts []spec.Mount) string {
+	root := r.store.GraphRoot()
+	for _, val := range mounts {
+		if strings.HasPrefix(root, val.Source) {
+			return "graphRootMounted=1"
+		}
+	}
+	return ""
+}
-- 
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