diff options
| author | Rahat Mahmood <rahat@google.com> | 2021-09-23 15:50:08 -0700 |
|---|---|---|
| committer | gVisor bot <gvisor-bot@google.com> | 2021-09-23 15:54:02 -0700 |
| commit | 2b776633303f696a552d41ead53b33e594c812d1 (patch) | |
| tree | 713eff4f409c08387fdf7655964af550bd37bc41 /pkg/sentry/fsimpl/sys/sys.go | |
| parent | 93ac1557751a0c17a85f49d715b96833acf39dc6 (diff) | |
Create the cgroupfs mount point in sysfs.
Create the /sys/fs/cgroup directory when cgroups are available. This
creates the empty directory to serve as the mountpoint, actually
mounting cgroups is left to the launcher/userspace. This is consistent
with Linux behaviour.
Without this mountpoint, getdents(2) on /sys/fs indicates an empty
directory even if the launcher mounts cgroupfs at /sys/fs/cgroup. The
launcher can't create the mountpoint directory since sysfs doesn't
support mkdir.
PiperOrigin-RevId: 398596698
Diffstat (limited to 'pkg/sentry/fsimpl/sys/sys.go')
| -rw-r--r-- | pkg/sentry/fsimpl/sys/sys.go | 14 |
1 files changed, 13 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), |