I have a cell modem connected to my server that I want to use as a means to get notification emails out when the landline dies.
To nicely separate normal network access and this exceptional cell modem access, I created a network namespace and created the network device in there as the only device. To have a program use the cell modem I simply use
ip netns exec.
The wrinkle is that I want to allow any user to run any program they wish in the namespace, but
netns exec requires root. My solution is as follows:
#!/bin/sh cmd_line="$@" /bin/ip netns exec oob \ /usr/bin/sudo -u "#$SUDO_UID" -g "#$SUDO_GID" /bin/sh -c "$cmd_line"
ALL ALL=NOPASSWD: /usr/local/sbin/_oob_shim
I figure the only way to run the shim without already being root or knowing the root password is through sudo, and I can trust sudo to set $SUDO_UID and $SUDO_GID to the right values.
Am I opening myself up to significant risk? Or, should I say am I missing any obvious caveats?