'ip vrf' follows the user semnatics established by 'ip netns'.
The 'ip vrf' subcommand supports 3 usages:
1. Run a command against a given vrf:
ip vrf exec NAME CMD
Uses the recently committed cgroup/sock BPF option. vrf directory
is added to cgroup2 mount. Individual vrfs are created under it. BPF
filter attached to vrf/NAME cgroup2 to set sk_bound_dev_if to the VRF
device index. From there the current process (ip's pid) is addded to
the cgroups.proc file and the given command is exected. In doing so
all AF_INET/AF_INET6 (ipv4/ipv6) sockets are automatically bound to
the VRF domain.
The association is inherited parent to child allowing the command to
be a shell from which other commands are run relative to the VRF.
2. Show the VRF a process is bound to:
ip vrf id
This command essentially looks at /proc/pid/cgroup for a "::/vrf/"
entry with the VRF name following.
3. Show process ids bound to a VRF
ip vrf pids NAME
This command dumps the file MNT/vrf/NAME/cgroup.procs since that file
shows the process ids in the particular vrf cgroup.
Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
