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This patch adds vTPM support for Linux to libcontainer.
The functionality is based on a recently added vtpm_proxy driver, which
is becoming available in Linux 4.8. The driver provides /dev/vtpmx, on
which an ioctl is called that spawns a TPM device in the host's /dev
directory and returns an anonymous file-descriptor on which a TPM emulator
can listen for TPM commands. If we for example created /dev/tpm12 on the
host we make this device available as /dev/tpm0 inside the container. We
also add its major and minor numbers to the device cgroup.
We implement a VTPM class that allows us to create the device and starts
a TPM emulator 'swtpm', to which it passes the anonymous file descriptor.
Besides that, the user can choose to have the vTPM create certificates in
a step that simulates TPM manufacturing. We do this by calling the external
swtpm_setup program, which is part of the swtpm project.
VTPM support is added inside the JSON configuration as follows:
[...]
"linux": {
"resources": {
"devices": [
{
"allow": false,
"access": "rwm"
}
] ,
"vtpms": [
{
"statePath": "/tmp/tpm-1",
"createCerts": true
},
]
},
[...]
This JSON markup makes a single TPM available inside the created container.
o The statPath parameter indicates the directory where the TPM emulator
'swtpm' writes the state of the TPM device to.
o The createCerts parameter indicates that certificates for the
TPM are to be created.
The current implementation does not support checkpointing, so checkpointing
of a container with an attached vTPM is prevented.
The swtpm project is available here : https://github.com/stefanberger/swtpm
The libtpms project is available here: https://github.com/stefanberger/libtpms
Signed-off-by: Stefan Berger <[email protected]>
Signed-off-by: Stefan Berger <[email protected]>
Signed-off-by: Stefan Berger <[email protected]>- Loading branch information
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,115 @@ | ||
| // + build linux | ||
|
|
||
| package vtpmhelper | ||
|
|
||
| import ( | ||
| "fmt" | ||
| "os" | ||
| "syscall" | ||
|
|
||
| "github.com/opencontainers/runc/libcontainer/configs" | ||
| "github.com/opencontainers/runc/libcontainer/vtpm" | ||
|
|
||
| "github.com/opencontainers/runtime-spec/specs-go" | ||
| "golang.org/x/sys/unix" | ||
| ) | ||
|
|
||
| func addVTPMDevice(spec *specs.Spec, hostpath, devpath string, major, minor uint32) { | ||
| var filemode os.FileMode = 0600 | ||
|
|
||
| device := specs.LinuxDevice{ | ||
| Path: hostpath, | ||
| Devpath: devpath, | ||
| Type: "c", | ||
| Major: int64(major), | ||
| Minor: int64(minor), | ||
| FileMode: &filemode, | ||
| } | ||
| spec.Linux.Devices = append(spec.Linux.Devices, device) | ||
|
|
||
| major_p := new(int64) | ||
| *major_p = int64(major) | ||
| minor_p := new(int64) | ||
| *minor_p = int64(minor) | ||
|
|
||
| ld := &specs.LinuxDeviceCgroup{ | ||
| Allow: true, | ||
| Type: "c", | ||
| Major: major_p, | ||
| Minor: minor_p, | ||
| Access: "rwm", | ||
| } | ||
| spec.Linux.Resources.Devices = append(spec.Linux.Resources.Devices, *ld) | ||
| } | ||
|
|
||
| // Create a VTPM | ||
| func CreateVTPM(spec *specs.Spec, vtpmdev *specs.VTPM, devnum int) (*vtpm.VTPM, error) { | ||
|
|
||
| vtpm, err := vtpm.NewVTPM(vtpmdev.Statepath, vtpmdev.StatepathIsManaged, vtpmdev.TPMVersion, vtpmdev.CreateCertificates, vtpmdev.Runas, vtpmdev.PcrBanks) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
|
||
| // Start the vTPM process; once stopped, the device pair will | ||
| // also disappear | ||
| err, vtpm.CreatedStatepath = vtpm.Start() | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
|
||
| hostdev := vtpm.GetTPMDevname() | ||
| major, minor := vtpm.GetMajorMinor() | ||
|
|
||
| devpath := fmt.Sprintf("/dev/tpm%d", devnum) | ||
| addVTPMDevice(spec, hostdev, devpath, major, minor) | ||
|
|
||
| // check if /dev/vtpmrm%d is available | ||
| host_tpmrm := fmt.Sprintf("/dev/tpmrm%d", vtpm.GetTPMDevNum()) | ||
| if fileInfo, err := os.Lstat(host_tpmrm); err == nil { | ||
| if stat_t, ok := fileInfo.Sys().(*syscall.Stat_t); ok { | ||
| devNumber := stat_t.Rdev | ||
| devpath = fmt.Sprintf("/dev/tpmrm%d", devnum) | ||
| addVTPMDevice(spec, host_tpmrm, devpath, unix.Major(devNumber), unix.Minor(devNumber)) | ||
| } | ||
| } | ||
|
|
||
| return vtpm, nil | ||
| } | ||
|
|
||
| func setVTPMHostDevOwner(vtpm *vtpm.VTPM, uid, gid int) error { | ||
| hostdev := vtpm.GetTPMDevname() | ||
| // adapt ownership of the device since only root can access it | ||
| if err := os.Chown(hostdev, uid, gid); err != nil { | ||
| return err | ||
| } | ||
|
|
||
| host_tpmrm := fmt.Sprintf("/dev/tpmrm%d", vtpm.GetTPMDevNum()) | ||
| if _, err := os.Lstat(host_tpmrm); err == nil { | ||
| // adapt ownership of the device since only root can access it | ||
| if err := os.Chown(host_tpmrm, uid, gid); err != nil { | ||
| return err | ||
| } | ||
| } | ||
|
|
||
| return nil | ||
| } | ||
|
|
||
| // SetVTPMHostDevsOwner sets the owner of the host devices to the | ||
| // container root's mapped user id; if root inside the container is | ||
| // uid 1000 on the host, the devices will be owned by uid 1000. | ||
| func SetVTPMHostDevsOwner(config *configs.Config, uid, gid int) error { | ||
| if uid != 0 { | ||
| for _, vtpm := range config.VTPMs { | ||
| if err := setVTPMHostDevOwner(vtpm, uid, gid); err != nil { | ||
| return err | ||
| } | ||
| } | ||
| } | ||
| return nil | ||
| } | ||
|
|
||
| func DestroyVTPMs(vtpms []*vtpm.VTPM) { | ||
| for _, vtpm := range vtpms { | ||
| vtpm.Stop(vtpm.CreatedStatepath) | ||
| } | ||
| } |
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