Add support for serial device

[faquad]

Issue description

I want to access /dev/ttyUSB0 device from ego using github.com/bugst/go-serial.
i can mount the device in docker compose but ego does not see this device

To reproduce

Steps to reproduce the behavior:

in plain go i can access /dev/ttyUSB but does not see /dev/ttyUSB

Expected behavior

Would good to have an option to mount a device like a volume or file.

[thomasten]

Hi, try mounting the device in EGo: https://docs.edgeless.systems/ego/reference/config
This may work for character devices. Note that mounted devices must be considered untrusted.

[faquad]

Hi,
i alread tried that by mounting as volume in enclave.json

{
            "source": "/dev/ttyUSB0",
            "target": "/dev/ttyUSB0",
            "type": "hostfs"
        }

and expose as device in docker-compose.yml

devices:
      - /dev/sgx_enclave
      - /dev/sgx_provision
      - /dev/sgx_vepc
      - /dev/ttyUSB0 

device is a character device:

ls -l /dev/ttyUSB0 
crw-rw---- 1 root dialout 188, 0 Oct  8 09:40 /dev/ttyUSB0

error:
panic: Invalid serial port: error getting term settings: inappropriate ioctl for device

the connect code is simple like so

import (
	"go.bug.st/serial"
)
var lSerialModeS = &serial.Mode{
	BaudRate: 115200,
	Parity:   serial.NoParity,
	DataBits: 8,
	StopBits: serial.OneStopBit,
}
func connect()  {
 _,err := serial.Open("/dev/ttyUSB0", lSerialModeS)
if err!=nil  {
 panic(err)
}
}

[thomasten]

ioctl support is very limited, so this won't work then unfortunately.