Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

[release/1.5] oci: use readonly mount to read user/group info #6503

Merged
merged 1 commit into from Feb 3, 2022
Merged

[release/1.5] oci: use readonly mount to read user/group info #6503

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Jump to
Jump to file
Failed to load files.
Diff view
Diff view
26 changes: 26 additions & 0 deletions oci/spec_opts.go
View file
Open in desktop
Expand Up @@ -590,6 +590,8 @@ func WithUser(userstr string) SpecOpts {
if err != nil {
return err
}

mounts = tryReadonlyMounts(mounts)
return mount.WithTempMount(ctx, mounts, f)
default:
return fmt.Errorf("invalid USER value %s", userstr)
Expand Down Expand Up @@ -643,6 +645,8 @@ func WithUserID(uid uint32) SpecOpts {
if err != nil {
return err
}

mounts = tryReadonlyMounts(mounts)
return mount.WithTempMount(ctx, mounts, func(root string) error {
user, err := UserFromPath(root, func(u user.User) bool {
return u.Uid == int(uid)
Expand Down Expand Up @@ -692,6 +696,8 @@ func WithUsername(username string) SpecOpts {
if err != nil {
return err
}

mounts = tryReadonlyMounts(mounts)
return mount.WithTempMount(ctx, mounts, func(root string) error {
user, err := UserFromPath(root, func(u user.User) bool {
return u.Name == username
Expand Down Expand Up @@ -776,6 +782,8 @@ func WithAdditionalGIDs(userstr string) SpecOpts {
if err != nil {
return err
}

mounts = tryReadonlyMounts(mounts)
return mount.WithTempMount(ctx, mounts, setAdditionalGids)
}
}
Expand Down Expand Up @@ -1264,3 +1272,21 @@ func WithDevShmSize(kb int64) SpecOpts {
return ErrNoShmMount
}
}

// tryReadonlyMounts is used by the options which are trying to get user/group
// information from container's rootfs. Since the option does read operation
// only, this helper will append ReadOnly mount option to prevent linux kernel
// from syncing whole filesystem in umount syscall.
//
// TODO(fuweid):
//
// Currently, it only works for overlayfs. I think we can apply it to other
// kinds of filesystem. Maybe we can return `ro` option by `snapshotter.Mount`
// API, when the caller passes that experimental annotation
// `containerd.io/snapshot/readonly.mount` something like that.
func tryReadonlyMounts(mounts []mount.Mount) []mount.Mount {
if len(mounts) == 1 && mounts[0].Type == "overlay" {
mounts[0].Options = append(mounts[0].Options, "ro")
}
return mounts
}