linux/arch
David Herrmann f5dd3d0c96 net: introduce SO_BINDTOIFINDEX sockopt
This introduces a new generic SOL_SOCKET-level socket option called
SO_BINDTOIFINDEX. It behaves similar to SO_BINDTODEVICE, but takes a
network interface index as argument, rather than the network interface
name.

User-space often refers to network-interfaces via their index, but has
to temporarily resolve it to a name for a call into SO_BINDTODEVICE.
This might pose problems when the network-device is renamed
asynchronously by other parts of the system. When this happens, the
SO_BINDTODEVICE might either fail, or worse, it might bind to the wrong
device.

In most cases user-space only ever operates on devices which they
either manage themselves, or otherwise have a guarantee that the device
name will not change (e.g., devices that are UP cannot be renamed).
However, particularly in libraries this guarantee is non-obvious and it
would be nice if that race-condition would simply not exist. It would
make it easier for those libraries to operate even in situations where
the device-name might change under the hood.

A real use-case that we recently hit is trying to start the network
stack early in the initrd but make it survive into the real system.
Existing distributions rename network-interfaces during the transition
from initrd into the real system. This, obviously, cannot affect
devices that are up and running (unless you also consider moving them
between network-namespaces). However, the network manager now has to
make sure its management engine for dormant devices will not run in
parallel to these renames. Particularly, when you offload operations
like DHCP into separate processes, these might setup their sockets
early, and thus have to resolve the device-name possibly running into
this race-condition.

By avoiding a call to resolve the device-name, we no longer depend on
the name and can run network setup of dormant devices in parallel to
the transition off the initrd. The SO_BINDTOIFINDEX ioctl plugs this
race.

Reviewed-by: Tom Gundersen <teg@jklm.no>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-01-17 14:55:51 -08:00
..
alpha net: introduce SO_BINDTOIFINDEX sockopt 2019-01-17 14:55:51 -08:00
arc arch: remove redundant UAPI generic-y defines 2019-01-06 10:22:15 +09:00
arm ARM: orion5x: Include platform_data/dsa.h 2019-01-17 11:31:24 -08:00
arm64 ARM: SoC fixes 2019-01-14 10:34:14 +12:00
c6x arch: restore generic-y += shmparam.h for some architectures 2019-01-06 18:16:11 -08:00
csky csky: fixup compile error with CPU 810. 2019-01-10 04:37:37 -08:00
h8300 arch: restore generic-y += shmparam.h for some architectures 2019-01-06 18:16:11 -08:00
hexagon arch: restore generic-y += shmparam.h for some architectures 2019-01-06 18:16:11 -08:00
ia64 net: introduce SO_BINDTOIFINDEX sockopt 2019-01-17 14:55:51 -08:00
m68k arch: restore generic-y += shmparam.h for some architectures 2019-01-06 18:16:11 -08:00
microblaze arch: restore generic-y += shmparam.h for some architectures 2019-01-06 18:16:11 -08:00
mips net: introduce SO_BINDTOIFINDEX sockopt 2019-01-17 14:55:51 -08:00
nds32 arch: remove redundant UAPI generic-y defines 2019-01-06 10:22:15 +09:00
nios2 arch: remove redundant UAPI generic-y defines 2019-01-06 10:22:15 +09:00
openrisc arch/openrisc: Fix issues with access_ok() 2019-01-08 18:22:30 -08:00
parisc net: introduce SO_BINDTOIFINDEX sockopt 2019-01-17 14:55:51 -08:00
powerpc cross-tree: phase out dma_zalloc_coherent() 2019-01-08 07:58:37 -05:00
riscv Fix a handful of audit-related issue 2019-01-07 08:45:47 -08:00
s390 net: introduce SO_BINDTOIFINDEX sockopt 2019-01-17 14:55:51 -08:00
sh Kbuild late updates for v4.21 2019-01-06 16:33:10 -08:00
sparc net: introduce SO_BINDTOIFINDEX sockopt 2019-01-17 14:55:51 -08:00
um Merge branch 'akpm' (patches from Andrew) 2019-01-05 09:16:18 -08:00
unicore32 arch: restore generic-y += shmparam.h for some architectures 2019-01-06 18:16:11 -08:00
x86 KVM fixes for 5.0-rc2 2019-01-12 10:39:43 -08:00
xtensa net: introduce SO_BINDTOIFINDEX sockopt 2019-01-17 14:55:51 -08:00
.gitignore
Kconfig jump_label: move 'asm goto' support test to Kconfig 2019-01-06 09:46:51 +09:00