[RESEND,v7,0/3] Make neighbor eviction controllable by userspace

Message

James Prestwood Oct. 25, 2021, 4:45 p.m. UTC

v1 -> v2:

 - It was suggested by Daniel Borkmann to extend the neighbor table settings
   rather than adding IPv4/IPv6 options for ARP/NDISC separately. I agree
   this way is much more concise since there is now only one place where the
   option is checked and defined.
 - Moved documentation/code into the same patch
 - Explained in more detail the test scenario and results

v2 -> v3:

 - Renamed 'skip_perm' to 'nocarrier'. The way this parameter is used
   matches this naming.
 - Changed logic to still flush if 'nocarrier' is false.

v3 -> v4:

 - Moved NDTPA_EVICT_NOCARRIER after NDTPA_PAD

v4 -> v5:

 - Went back to the original v1 patchset and changed:
 - Used ANDCONF for IN_DEV macro
 - Got RCU lock prior to __in_dev_get_rcu(). Do note that the logic
   here was extended to handle if __in_dev_get_rcu() fails. If this
   happens the existing behavior should be maintained and set the
   carrier down. I'm unsure if get_rcu() can fail in this context
   though. Similar logic was used for in6_dev_get.
 - Changed ndisc_evict_nocarrier to use a u8, proper handler, and
   set min/max values.

v5 -> v6

 - Added selftests for both sysctl options
 - (arp) Used __in_dev_get_rtnl rather than getting the rcu lock
 - (ndisc) Added in6_dev_put
 - (ndisc) Check 'all' option as well as device specific

v6 -> v7

 - Corrected logic checking all and netdev option

Resend v7:

 - Fixed (hopefully) the issue with CC's only getting the cover letter

James Prestwood (3):
  net: arp: introduce arp_evict_nocarrier sysctl parameter
  net: ndisc: introduce ndisc_evict_nocarrier sysctl parameter
  selftests: net: add arp_ndisc_evict_nocarrier

 Documentation/networking/ip-sysctl.rst        |  18 ++
 include/linux/inetdevice.h                    |   2 +
 include/linux/ipv6.h                          |   1 +
 include/uapi/linux/ip.h                       |   1 +
 include/uapi/linux/ipv6.h                     |   1 +
 include/uapi/linux/sysctl.h                   |   1 +
 net/ipv4/arp.c                                |  11 +-
 net/ipv4/devinet.c                            |   4 +
 net/ipv6/addrconf.c                           |  12 ++
 net/ipv6/ndisc.c                              |  12 +-
 .../net/arp_ndisc_evict_nocarrier.sh          | 181 ++++++++++++++++++
 11 files changed, 242 insertions(+), 2 deletions(-)
 create mode 100755 tools/testing/selftests/net/arp_ndisc_evict_nocarrier.sh