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* [PATCH net-next v2 0/2] ipv6: update NUD_FAILED neighbors from NA messages
@ 2026-09-15  5:01 Lawrence Lee
  2026-09-15  5:01 ` [PATCH net-next v2 1/2] " Lawrence Lee
                   ` (2 more replies)
  0 siblings, 3 replies; 4+ messages in thread
From: Lawrence Lee @ 2026-09-15  5:01 UTC (permalink / raw)
  To: David Ahern, Ido Schimmel, David S. Miller, Eric Dumazet,
	Jakub Kicinski, Paolo Abeni
  Cc: Simon Horman, Randy Dunlap, netdev, Arun Ajith S, Roopa Prabhu,
	Jaehee Park, Jonathan Corbet, Shuah Khan, Shuah Khan, linux-doc,
	linux-kselftest, linux-kernel, Alexander Aring, linux-wpan,
	linux-bluetooth

Neighbor Advertisements for existing NUD_FAILED entries are currently
ignored. This can leave a first-hop router with an unusable neighbor after
the host becomes reachable and announces itself, particularly when
forwarding is offloaded away from the kernel and traffic destined to the
FAILED neighbor is unable to trigger the kernel's normal neighbor
resolution process.
Allowing neighbor entries to be updated from NAs already received by the
kernel is preferable since it creates less work compared to periodically
probing FAILED neighbors (e.g. using NTF_EXT_MANAGED).

Extend accept_untracked_na to treat FAILED entries like absent entries.
Require a target link-layer address, IPv6 forwarding, and acceptance by the
sysctl, including its source-prefix check in mode 2. Recover the entry only
to STALE, including for solicited NAs, to maintain parity with handling of
non-existent neighbor cache entries.

Patch #1 implements the behavior and updates RFC 9131-related comments and
accept_untracked_na documentation.

Patch #2 extends ndisc_unsolicited_na_test.sh to cover FAILED-entry
recovery and each acceptance gate, including in-prefix and out-of-prefix
mode 2.

Thanks to Ido Schimmel for feedback on the original RFC.

---
v2:
- Full implementation of logic to update FAILED entries to STALE.
- Update the RFC 9131-related comments and sysctl documentation.
- Add selftests to verify state changes only when the accept_untracked_na
  setting is enabled.

v1 (RFC):
https://lore.kernel.org/r/20260813233344.445265-1-lfqlee314@gmail.com

Testing:
- x86_64 current-config and allyesconfig builds with W=1
- tools/testing/selftests/net/ndisc_unsolicited_na_test.sh: 14 passed
- Local NIPA checks: all substantive checks passed
- Sashiko local review completed

Lawrence Lee (2):
  ipv6: update NUD_FAILED neighbors from NA messages
  selftests: net: test untracked NA recovery of FAILED neighbors

 Documentation/networking/ip-sysctl.rst        |  28 ++--
 include/net/ndisc.h                           |  15 ++-
 net/6lowpan/ndisc.c                           |  15 ++-
 net/ipv6/ndisc.c                              |  94 ++++++++-----
 .../net/ndisc_unsolicited_na_test.sh          | 124 +++++++++++++++---
 5 files changed, 201 insertions(+), 75 deletions(-)


base-commit: 272a65db243bfa34b9277632830e0e06d7e3518e
-- 
2.43.0

^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2026-09-15  5:26 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2026-09-15  5:01 [PATCH net-next v2 0/2] ipv6: update NUD_FAILED neighbors from NA messages Lawrence Lee
2026-09-15  5:01 ` [PATCH net-next v2 1/2] " Lawrence Lee
2026-09-15  5:01 ` [PATCH net-next v2 2/2] selftests: net: test untracked NA recovery of FAILED neighbors Lawrence Lee
2026-09-15  5:26 ` [PATCH net-next v2 0/2] ipv6: update NUD_FAILED neighbors from NA messages Randy Dunlap

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