From: Alistair Francis <alistair.francis@wdc.com>

The TLS 1.3 specification allows the TLS client or server to send a
KeyUpdate. This is generally used when the sequence is about to
overflow or after a certain amount of bytes have been encrypted.

The TLS spec doesn't mandate the conditions though, so a KeyUpdate
can be sent by the TLS client or server at any time. This includes
when running NVMe-OF over a TLS 1.3 connection.

As such Linux should be able to handle a KeyUpdate event, as the
other NVMe side could initiate a KeyUpdate.

Upcoming WD NVMe-TCP hardware controllers implement TLS support
and send KeyUpdate requests.

This series builds on top of the existing TLS EKEYEXPIRED work,
which already detects a KeyUpdate request. We can now pass that
information up to the NVMe layer (target and host) and then pass
it up to userspace.

Userspace (ktls-utils) will need to save the connection state
in the keyring during the initial handshake. The kernel then
provides the key serial back to userspace when handling a
KeyUpdate. Userspace can use this to restore the connection
information and then update the keys, this final process
is similar to the initial handshake.

This series depends on the read_sock_cmsg() kernel patch:
https://lore.kernel.org/kernel-tls-handshake/20260217222033.1929211-1-cel@kernel.org

ktls-utils (tlshd) userspace patches are available at:
https://lore.kernel.org/kernel-tls-handshake/CAKmqyKNpFhPtM8HAkgRMKQA8_N7AgoeqaSTe2=0spPnb+Oz2ng@mail.gmail.com/T/#mb277f5c998282666d0f41cc02f4abf516fcc4e9c

Link: https://datatracker.ietf.org/doc/html/rfc8446#section-4.6.3

Based-on: 20260217222033.1929211-1-cel@kernel.org

v7:
 - Don't use recvmsg() (see [1]) instead use read_sock_cmsg()
 - Remove reviews from patch 4, as it changed a bit to support read_sock_cmsg()
v6:
 - Don't free handshake request on completion (handshake_sk_destruct_req())
 - Add handshake_req_keyupdate() which reuses existing handshake request
   for a KeyUpdate
 - Other small improvements and tidyups
v5:
 - Cleanup code flow for nvme-tcp
 - When using recvmsg in the host code first check for MSG_CTRUNC
   in the msg_flags returned from recvmsg() and use that to determine
   if it's a control message
 - Drop clientkeyupdaterequest and serverkeyupdaterequest
v4:
 - Don't stop the keep-alive timer
 - Remove any support for sending a KeyUpdate
 - Add tls_client_keyupdate_psk()' and 'tls_server_keyupdate_psk()'
 - Code cleanups
 - Change order of patches
v3:
 - Rebase on the recvmsg() workflow patch
 - Add debugfs support for the host
 - Don't cancel an ongoing request
 - Ensure a request is destructed on completion
v2:
 - Change "key-serial" to "session-id"
 - Fix reported build failures
 - Drop tls_clear_err() function
 - Stop keep alive timer during KeyUpdate
 - Drop handshake message decoding in the NVMe layer

1: https://lists.infradead.org/pipermail/linux-nvme/2026-February/061252.html

Alistair Francis (5):
  net/handshake: Store the key serial number on completion
  net/handshake: Define handshake_req_keyupdate
  net/handshake: Support KeyUpdate message types
  nvme-tcp: Support KeyUpdate
  nvmet-tcp: Support KeyUpdate

 Documentation/netlink/specs/handshake.yaml |  20 +-
 Documentation/networking/tls-handshake.rst |   1 +
 drivers/nvme/host/tcp.c                    |  80 +++++++-
 drivers/nvme/target/tcp.c                  | 213 ++++++++++++++-------
 include/net/handshake.h                    |  11 +-
 include/uapi/linux/handshake.h             |  12 ++
 net/handshake/genl.c                       |   5 +-
 net/handshake/handshake.h                  |   2 +
 net/handshake/request.c                    |  97 ++++++++++
 net/handshake/tlshd.c                      |  97 +++++++++-
 net/sunrpc/svcsock.c                       |   4 +-
 net/sunrpc/xprtsock.c                      |   4 +-
 12 files changed, 467 insertions(+), 79 deletions(-)

-- 
2.53.0