To enable kernel consumers of TLS to request a TLS handshake, add
support to net/handshake/ to request a handshake upcall.

This patch also acts as a template for adding handshake upcall
support for other kernel transport layer security providers.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

When a kernel consumer needs a transport layer security session, it
first needs a handshake to negotiate and establish a session. This
negotiation can be done in user space via one of the several
existing library implementations, or it can be done in the kernel.

No in-kernel handshake implementations yet exist. In their absence,
we add a netlink service that can:

a. Notify a user space daemon that a handshake is needed.

b. Once notified, the daemon calls the kernel back via this
   netlink service to get the handshake parameters, including an
   open socket on which to establish the session.

c. Once the handshake is complete, the daemon reports the
   session status and other information via a second netlink
   operation. This operation marks that it is safe for the
   kernel to use the open socket and the security session
   established there.

The notification service uses a multicast group. Each handshake
mechanism (eg, tlshd) adopts its own group number so that the
handshake services are completely independent of one another. The
kernel can then tell via netlink_has_listeners() whether a handshake
service is active and prepared to handle a handshake request.

A new netlink operation, ACCEPT, acts like accept(2) in that it
instantiates a file descriptor in the user space daemon's fd table.
If this operation is successful, the reply carries the fd number,
which can be treated as an open and ready file descriptor.

While user space is performing the handshake, the kernel keeps its
muddy paws off the open socket. A second new netlink operation,
DONE, indicates that the user space daemon is finished with the
socket and it is safe for the kernel to use again. The operation
also indicates whether a session was established successfully.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Things that are not implemented:
- cable tests
- bitmaks in the requests don't work (needs multi-attr support in ynl.py)
- stats-get seems to return nonsense (not passing a bitmask properly?)
- notifications are not tested

Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

The openvswitch family has a fixed header, uses struct attrs and has array
values. This partial spec demonstrates these features in the YNL CLI. These
specs are sufficient to create, delete and dump datapaths and to dump vports:

$ ./tools/net/ynl/cli.py \
    --spec Documentation/netlink/specs/ovs_datapath.yaml \
    --do dp-new --json '{ "dp-ifindex": 0, "name": "demo", "upcall-pid": 0}'
None

$ ./tools/net/ynl/cli.py \
    --spec Documentation/netlink/specs/ovs_datapath.yaml \
    --dump dp-get --json '{ "dp-ifindex": 0 }'
[{'dp-ifindex': 3,
  'masks-cache-size': 256,
  'megaflow-stats': {'cache-hits': 0,
                     'mask-hit': 0,
                     'masks': 0,
                     'pad1': 0,
                     'padding': 0},
  'name': 'test',
  'stats': {'flows': 0, 'hit': 0, 'lost': 0, 'missed': 0},
  'user-features': {'dispatch-upcall-per-cpu',
                    'tc-recirc-sharing',
                    'unaligned'}},
 {'dp-ifindex': 48,
  'masks-cache-size': 256,
  'megaflow-stats': {'cache-hits': 0,
                     'mask-hit': 0,
                     'masks': 0,
                     'pad1': 0,
                     'padding': 0},
  'name': 'demo',
  'stats': {'flows': 0, 'hit': 0, 'lost': 0, 'missed': 0},
  'user-features': set()}]

$ ./tools/net/ynl/cli.py \
    --spec Documentation/netlink/specs/ovs_datapath.yaml \
    --do dp-del --json '{ "dp-ifindex": 0, "name": "demo"}'
None

$ ./tools/net/ynl/cli.py \
    --spec Documentation/netlink/specs/ovs_vport.yaml \
    --dump vport-get --json '{ "dp-ifindex": 3 }'
[{'dp-ifindex': 3,
  'ifindex': 3,
  'name': 'test',
  'port-no': 0,
  'stats': {'rx-bytes': 0,
            'rx-dropped': 0,
            'rx-errors': 0,
            'rx-packets': 0,
            'tx-bytes': 0,
            'tx-dropped': 0,
            'tx-errors': 0,
            'tx-packets': 0},
  'type': 'internal',
  'upcall-pid': [0],
  'upcall-stats': {'fail': 0, 'success': 0}}]

Signed-off-by: Donald Hunter <donald.hunter@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Add support for netlink families that add an optional fixed header structure
after the genetlink header and before any attributes. The fixed-header can be
specified on a per op basis, or once for all operations, which serves as a
default value that can be overridden.

Signed-off-by: Donald Hunter <donald.hunter@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Add support for decoding attributes that contain C structs.

Signed-off-by: Donald Hunter <donald.hunter@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

This attribute, which is part of ethtool's ring param configuration
allows the user to specify the maximum number of the packet's payload
that can be written directly to the device.

Example usage:
    # ethtool -G [interface] tx-push-buf-len [number of bytes]

Co-developed-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Shay Agroskin <shayagr@amazon.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/wireless/nl80211.c
  b27f07c50a73 ("wifi: nl80211: fix puncturing bitmap policy")
  cbbaf2bb829b ("wifi: nl80211: add a command to enable/disable HW timestamping")
https://lore.kernel.org/all/20230314105421.3608efae@canb.auug.org.au

tools/testing/selftests/net/Makefile
  62199e3f1658 ("selftests: net: Add VXLAN MDB test")
  13715acf8ab5 ("selftest: Add test for bind() conflicts.")

Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Chuck wanted to put the UAPI header in linux/net/ which seems
reasonable, allow genetlink families to choose the location.
It doesn't really matter for non-C-like languages.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Devlink is quite complex but put in the very basics so we can
incrementally fill in the commands as needed.

$ ./tools/net/ynl/cli.py --spec Documentation/netlink/specs/devlink.yaml \
    --dump get

[{'bus-name': 'netdevsim',
  'dev-name': 'netdevsim1',
  'dev-stats': {'reload-stats': {'reload-action-info': {'reload-action': 1,
                                                        'reload-action-stats': {'reload-stats-entry': [{'reload-stats-limit': 0,
                                                                                                        'reload-stats-value': 0}]}}},
                'remote-reload-stats': {'reload-action-info': {'reload-action': 2,
                                                               'reload-action-stats': {'reload-stats-entry': [{'reload-stats-limit': 0,
                                                                                                               'reload-stats-value': 0},
                                                                                                              {'reload-stats-limit': 1,
                                                                                                               'reload-stats-value': 0}]}}}},
  'reload-failed': 0}]

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>