SUBSYSTEM=="net", ACTION=="add", KERNEL=="can*", RUN+="/etc/udev/rules.d/setup_can_interfaces.sh"
And the setup_can_interfaces.sh:
#!/bin/bash
/sbin/ip link set $INTERFACE type can bitrate 1000000
/sbin/ifconfig $INTERFACE txqueuelen 1000
/sbin/ifconfig $INTERFACE up
Do not forget to add executable rights and then reload the udev rules:
udevadm control --reload-rules && udevadm trigger