diff options
| -rw-r--r-- | pkg/sentry/fsimpl/sys/sys.go | 14 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/sys/sys_test.go | 14 |
2 files changed, 27 insertions, 1 deletions
diff --git a/pkg/sentry/fsimpl/sys/sys.go b/pkg/sentry/fsimpl/sys/sys.go index f322d2747..7fcb2d26b 100644 --- a/pkg/sentry/fsimpl/sys/sys.go +++ b/pkg/sentry/fsimpl/sys/sys.go @@ -84,6 +84,18 @@ func (fsType FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt fs.MaxCachedDentries = maxCachedDentries fs.VFSFilesystem().Init(vfsObj, &fsType, fs) + k := kernel.KernelFromContext(ctx) + fsDirChildren := make(map[string]kernfs.Inode) + // Create an empty directory to serve as the mount point for cgroupfs when + // cgroups are available. This emulates Linux behaviour, see + // kernel/cgroup.c:cgroup_init(). Note that in Linux, userspace (typically + // the init process) is ultimately responsible for actually mounting + // cgroupfs, but the kernel creates the mountpoint. For the sentry, the + // launcher mounts cgroupfs. + if k.CgroupRegistry() != nil { + fsDirChildren["cgroup"] = fs.newDir(ctx, creds, defaultSysDirMode, nil) + } + root := fs.newDir(ctx, creds, defaultSysDirMode, map[string]kernfs.Inode{ "block": fs.newDir(ctx, creds, defaultSysDirMode, nil), "bus": fs.newDir(ctx, creds, defaultSysDirMode, nil), @@ -97,7 +109,7 @@ func (fsType FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt }), }), "firmware": fs.newDir(ctx, creds, defaultSysDirMode, nil), - "fs": fs.newDir(ctx, creds, defaultSysDirMode, nil), + "fs": fs.newDir(ctx, creds, defaultSysDirMode, fsDirChildren), "kernel": kernelDir(ctx, fs, creds), "module": fs.newDir(ctx, creds, defaultSysDirMode, nil), "power": fs.newDir(ctx, creds, defaultSysDirMode, nil), diff --git a/pkg/sentry/fsimpl/sys/sys_test.go b/pkg/sentry/fsimpl/sys/sys_test.go index 0a0d914cc..0c46a3a13 100644 --- a/pkg/sentry/fsimpl/sys/sys_test.go +++ b/pkg/sentry/fsimpl/sys/sys_test.go @@ -87,3 +87,17 @@ func TestSysRootContainsExpectedEntries(t *testing.T) { "power": linux.DT_DIR, }) } + +func TestCgroupMountpointExists(t *testing.T) { + // Note: The mountpoint is only created if cgroups are available. This is + // the VFS2 implementation of sysfs and the test runs with VFS2 enabled, so + // we expect to see the mount point unconditionally. + s := newTestSystem(t) + defer s.Destroy() + pop := s.PathOpAtRoot("/fs") + s.AssertAllDirentTypes(s.ListDirents(pop), map[string]testutil.DirentType{ + "cgroup": linux.DT_DIR, + }) + pop = s.PathOpAtRoot("/fs/cgroup") + s.AssertAllDirentTypes(s.ListDirents(pop), map[string]testutil.DirentType{ /*empty*/ }) +} |