diff --git a/daemon/oci_linux.go b/daemon/oci_linux.go index ab5d5b59b3..276d6abe95 100644 --- a/daemon/oci_linux.go +++ b/daemon/oci_linux.go @@ -19,6 +19,7 @@ import ( "github.com/docker/docker/container" dconfig "github.com/docker/docker/daemon/config" "github.com/docker/docker/errdefs" + "github.com/docker/docker/internal/rootless/mountopts" "github.com/docker/docker/oci" "github.com/docker/docker/oci/caps" "github.com/docker/docker/pkg/idtools" @@ -30,7 +31,6 @@ import ( "github.com/opencontainers/runc/libcontainer/cgroups" specs "github.com/opencontainers/runtime-spec/specs-go" "github.com/pkg/errors" - "golang.org/x/sys/unix" ) const inContainerInitPath = "/sbin/" + dconfig.DefaultInitBinary @@ -445,38 +445,6 @@ func ensureSharedOrSlave(path string) error { return nil } -// Get the set of mount flags that are set on the mount that contains the given -// path and are locked by CL_UNPRIVILEGED. This is necessary to ensure that -// bind-mounting "with options" will not fail with user namespaces, due to -// kernel restrictions that require user namespace mounts to preserve -// CL_UNPRIVILEGED locked flags. -func getUnprivilegedMountFlags(path string) ([]string, error) { - var statfs unix.Statfs_t - if err := unix.Statfs(path, &statfs); err != nil { - return nil, err - } - - // The set of keys come from https://github.com/torvalds/linux/blob/v4.13/fs/namespace.c#L1034-L1048. - unprivilegedFlags := map[uint64]string{ - unix.MS_RDONLY: "ro", - unix.MS_NODEV: "nodev", - unix.MS_NOEXEC: "noexec", - unix.MS_NOSUID: "nosuid", - unix.MS_NOATIME: "noatime", - unix.MS_RELATIME: "relatime", - unix.MS_NODIRATIME: "nodiratime", - } - - var flags []string - for mask, flag := range unprivilegedFlags { - if uint64(statfs.Flags)&mask == mask { - flags = append(flags, flag) - } - } - - return flags, nil -} - var ( mountPropagationMap = map[string]int{ "private": mount.PRIVATE, @@ -661,7 +629,7 @@ func withMounts(daemon *Daemon, daemonCfg *configStore, c *container.Container, // when runc sets up the root filesystem, it is already inside a user // namespace, and thus cannot change any flags that are locked. if daemonCfg.RemappedRoot != "" || userns.RunningInUserNS() { - unprivOpts, err := getUnprivilegedMountFlags(m.Source) + unprivOpts, err := mountopts.UnprivilegedMountFlags(m.Source) if err != nil { return err } diff --git a/internal/rootless/mountopts/mountopts_linux.go b/internal/rootless/mountopts/mountopts_linux.go new file mode 100644 index 0000000000..f4ecf710c8 --- /dev/null +++ b/internal/rootless/mountopts/mountopts_linux.go @@ -0,0 +1,39 @@ +package mountopts + +import ( + "golang.org/x/sys/unix" +) + +// UnprivilegedMountFlags gets the set of mount flags that are set on the mount that contains the given +// path and are locked by CL_UNPRIVILEGED. This is necessary to ensure that +// bind-mounting "with options" will not fail with user namespaces, due to +// kernel restrictions that require user namespace mounts to preserve +// CL_UNPRIVILEGED locked flags. +// +// TODO: Move to github.com/moby/sys/mount, and update BuildKit copy of this code as well (https://github.com/moby/buildkit/blob/v0.13.0/util/rootless/mountopts/mountopts_linux.go#L11-L18) +func UnprivilegedMountFlags(path string) ([]string, error) { + var statfs unix.Statfs_t + if err := unix.Statfs(path, &statfs); err != nil { + return nil, err + } + + // The set of keys come from https://github.com/torvalds/linux/blob/v4.13/fs/namespace.c#L1034-L1048. + unprivilegedFlags := map[uint64]string{ + unix.MS_RDONLY: "ro", + unix.MS_NODEV: "nodev", + unix.MS_NOEXEC: "noexec", + unix.MS_NOSUID: "nosuid", + unix.MS_NOATIME: "noatime", + unix.MS_RELATIME: "relatime", + unix.MS_NODIRATIME: "nodiratime", + } + + var flags []string + for mask, flag := range unprivilegedFlags { + if uint64(statfs.Flags)&mask == mask { + flags = append(flags, flag) + } + } + + return flags, nil +}