Subject: Re: [patch net-next rfc 0/7] net: introduce alternative names for network interfaces

From: Stephen Hemminger <[email-masked]>
Date: Fri, 19 Jul 2019 09:31:35 -0700

On Fri, 19 Jul 2019 13:00:22 +0200
Jiri Pirko <[email-masked]> wrote:

> From: Jiri Pirko <[email-masked]>
> 
> In the past, there was repeatedly discussed the IFNAMSIZ (16) limit for
> netdevice name length. Now when we have PF and VF representors
> with port names like "pfXvfY", it became quite common to hit this limit:
> 0123456789012345
> enp131s0f1npf0vf6
> enp131s0f1npf0vf22
> 
> Udev cannot rename these interfaces out-of-the-box and user needs to
> create custom rules to handle them.
> 
> Also, udev has multiple schemes of netdev names. From udev code:
>  * Type of names:
>  *   b<number>                             - BCMA bus core number
>  *   c<bus_id>                             - bus id of a grouped CCW or CCW device,
>  *                                           with all leading zeros stripped [s390]
>  *   o<index>[n<phys_port_name>|d<dev_port>]
>  *                                         - on-board device index number
>  *   s<slot>[f<function>][n<phys_port_name>|d<dev_port>]
>  *                                         - hotplug slot index number
>  *   x<MAC>                                - MAC address
>  *   [P<domain>]p<bus>s<slot>[f<function>][n<phys_port_name>|d<dev_port>]
>  *                                         - PCI geographical location
>  *   [P<domain>]p<bus>s<slot>[f<function>][u<port>][..][c<config>][i<interface>]
>  *                                         - USB port number chain
>  *   v<slot>                               - VIO slot number (IBM PowerVM)
>  *   a<vendor><model>i<instance>           - Platform bus ACPI instance id
>  *   i<addr>n<phys_port_name>              - Netdevsim bus address and port name
> 
> One device can be often renamed by multiple patterns at the
> same time (e.g. pci address/mac).
> 
> This patchset introduces alternative names for network interfaces.
> Main goal is to:
> 1) Overcome the IFNAMSIZ limitation
> 2) Allow to have multiple names at the same time (multiple udev patterns)
> 3) Allow to use alternative names as handle for commands
> 
> See following examples.
> 
> $ ip link
> 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
>     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
> 3: dummy0: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
>     link/ether 7e:a2:d4:b8:91:7a brd ff:ff:ff:ff:ff:ff
> 
> -> Add alternative names for dummy0:  
> 
> $ ip link altname add dummy0 name someothername
> $ ip link altname add dummy0 name someotherveryveryveryverylongname
> $ ip link
> 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
>     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
> 3: dummy0: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
>     link/ether 7e:a2:d4:b8:91:7a brd ff:ff:ff:ff:ff:ff
>     altname someothername
>     altname someotherveryveryveryverylongname
>   
> -> Add bridge brx, add it's alternative name and use alternative names to  
>    do enslavement.
> 
> $ ip link add name brx type bridge
> $ ip link altname add brx name mypersonalsuperspecialbridge
> $ ip link set someotherveryveryveryverylongname master mypersonalsuperspecialbridge
> $ ip link
> 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
>     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
> 3: dummy0: <BROADCAST,NOARP> mtu 1500 qdisc noop master brx state DOWN mode DEFAULT group default qlen 1000
>     link/ether 7e:a2:d4:b8:91:7a brd ff:ff:ff:ff:ff:ff
>     altname someothername
>     altname someotherveryveryveryverylongname
> 4: brx: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
>     link/ether 7e:a2:d4:b8:91:7a brd ff:ff:ff:ff:ff:ff
>     altname mypersonalsuperspecialbridge
> 
> -> Add ipv4 address to the bridge using alternative name:  
>     
> $ ip addr add 192.168.0.1/24 dev mypersonalsuperspecialbridge
> $ ip addr show mypersonalsuperspecialbridge     
> 4: brx: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000
>     link/ether 7e:a2:d4:b8:91:7a brd ff:ff:ff:ff:ff:ff
>     altname mypersonalsuperspecialbridge
>     inet 192.168.0.1/24 scope global brx
>        valid_lft forever preferred_lft forever
> 
> -> Delete one of dummy0 alternative names:  
> 
> $ ip link altname del someotherveryveryveryverylongname    
> $ ip link
> 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
>     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
> 3: dummy0: <BROADCAST,NOARP> mtu 1500 qdisc noop master brx state DOWN mode DEFAULT group default qlen 1000
>     link/ether 7e:a2:d4:b8:91:7a brd ff:ff:ff:ff:ff:ff
>     altname someothername
> 4: brx: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
>     link/ether 7e:a2:d4:b8:91:7a brd ff:ff:ff:ff:ff:ff
>     altname mypersonalsuperspecialbridge
> 
> TODO:
> - notifications for alternative names add/removal
> - sanitization of add/del cmds (similar to get link)
> - test more usecases and write selftests
> - extend support for other netlink ifaces (ovs for example)
> - add sysfs symlink altname->basename?
> 
> Jiri Pirko (7):
>   net: procfs: use index hashlist instead of name hashlist
>   net: introduce name_node struct to be used in hashlist
>   net: rtnetlink: add commands to add and delete alternative ifnames
>   net: rtnetlink: put alternative names to getlink message
>   net: rtnetlink: unify the code in __rtnl_newlink get dev with the rest
>   net: rtnetlink: introduce helper to get net_device instance by ifname
>   net: rtnetlink: add possibility to use alternative names as message
>     handle
> 
>  include/linux/netdevice.h      |  14 ++-
>  include/uapi/linux/if.h        |   1 +
>  include/uapi/linux/if_link.h   |   3 +
>  include/uapi/linux/rtnetlink.h |   7 ++
>  net/core/dev.c                 | 152 ++++++++++++++++++++++----
>  net/core/net-procfs.c          |   4 +-
>  net/core/rtnetlink.c           | 192 +++++++++++++++++++++++++++++----
>  security/selinux/nlmsgtab.c    |   4 +-
>  8 files changed, 334 insertions(+), 43 deletions(-)
> 

You might want to add altname/ object property in sysfs?
I.e
   /sys/class/net/eth0/altname/