[PATCH net-next v4 00/15] Add Management Component Transport Protocol support

[PATCH net-next v4 00/15] Add Management Component Transport Protocol support

[Jeremy Kerr]

This series adds core MCTP support to the kernel. From the Kconfig
description:

  Management Component Transport Protocol (MCTP) is an in-system
  protocol for communicating between management controllers and
  their managed devices (peripherals, host processors, etc.). The
  protocol is defined by DMTF specification DSP0236.

  This option enables core MCTP support. For communicating with other
  devices, you'll want to enable a driver for a specific hardware
  channel.

This implementation allows a sockets-based API for sending and receiving
MCTP messages via sendmsg/recvmsg on SOCK_DGRAM sockets. Kernel stack
control is all via netlink, using existing RTM_* messages. The userspace
ABI change is fairly small; just the necessary AF_/ETH_P_/ARPHDR_
constants, a new sockaddr, and a new netlink attribute.

For MAINTAINERS, I've just included netdev@ as the list entry. I'm happy
to alter this based on preferences here - an alternative would be the
OpenBMC list (the main user of the MCTP interface), or we can create a
new list entirely.

We have a couple of interface drivers almost ready to go at the moment,
but those can wait until the core code has some review.

This is v4 of the series; v1 and v2 were both RFC.

selinux folks: CCing 01/15 due to the new PF_MCTP protocol family.

linux-doc folks: CCing 15/15 for the new MCTP overview document.

Review, comments, questions etc. are most welcome.

Cheers,


Jeremy

v2:
 - change to match spec terminology: controller -> component
 - require specific capabilities for bind() & sendmsg()
 - add address and tag defintions to uapi
 - add selinux AF_MCTP table definitions
 - remove strict cflags; warnings are present in common headers

v3:
 - require caps for MCTP bind() & send()
 - comment typo fixes
 - switch to an array for local EIDs
 - fix addrinfo dump iteration & error path
 - add RTM_DELADDR
 - remove GENMASK() and BIT() from uapi

v4:
 - drop tun patch; that can be submitted separately
 - keep nipa happy: add maintainer CCs, including doc and selinux
 - net-next rebase
 - Include AF_MCTP in af_family_slock_keys and pf_family_names
 - Introduce MODULE_ definitions earlier
 - upstream change: set_link_af no longer called with RTNL held
 - add kdoc for net_device.mctp_ptr
 - don't inline mctp_rt_match_eid
 - require rtm_type == RTN_UNICAST in route management handlers
 - remove unused RTAX policy table
 - fix mctp_sock->keys rcu annotations
 - fix spurious rcu_read_unlock in route input

Jeremy Kerr (10):
  mctp: Add MCTP base
  mctp: Add base socket/protocol definitions
  mctp: Add base packet definitions
  mctp: Add sockaddr_mctp to uapi
  mctp: Add initial driver infrastructure
  mctp: Add device handling and netlink interface
  mctp: Add initial routing framework
  mctp: Populate socket implementation
  mctp: Implement message fragmentation & reassembly
  mctp: Add MCTP overview document

Matt Johnston (6):
  mctp: Add netlink route management
  mctp: Add neighbour implementation
  mctp: Add neighbour netlink interface
  mctp: Add dest neighbour lladdr to route output
  mctp: Allow per-netns default networks
  mctp: Allow MCTP on tun devices

 Documentation/networking/index.rst  |    1 +
 Documentation/networking/mctp.rst   |  213 ++++++
 MAINTAINERS                         |   12 +
 drivers/net/Kconfig                 |    2 +
 drivers/net/Makefile                |    1 +
 drivers/net/mctp/Kconfig            |    8 +
 drivers/net/mctp/Makefile           |    0
 include/linux/netdevice.h           |    3 +
 include/linux/socket.h              |    6 +-
 include/net/mctp.h                  |  235 ++++++
 include/net/mctpdevice.h            |   36 +
 include/net/net_namespace.h         |    4 +
 include/net/netns/mctp.h            |   36 +
 include/uapi/linux/if_arp.h         |    1 +
 include/uapi/linux/if_ether.h       |    3 +
 include/uapi/linux/if_link.h        |   10 +
 include/uapi/linux/mctp.h           |   36 +
 net/Kconfig                         |    1 +
 net/Makefile                        |    1 +
 net/mctp/Kconfig                    |   13 +
 net/mctp/Makefile                   |    3 +
 net/mctp/af_mctp.c                  |  396 ++++++++++
 net/mctp/device.c                   |  427 +++++++++++
 net/mctp/neigh.c                    |  342 +++++++++
 net/mctp/route.c                    | 1095 +++++++++++++++++++++++++++
 security/selinux/hooks.c            |    4 +-
 security/selinux/include/classmap.h |    4 +-
 27 files changed, 2890 insertions(+), 3 deletions(-)
 create mode 100644 Documentation/networking/mctp.rst
 create mode 100644 drivers/net/mctp/Kconfig
 create mode 100644 drivers/net/mctp/Makefile
 create mode 100644 include/net/mctp.h
 create mode 100644 include/net/mctpdevice.h
 create mode 100644 include/net/netns/mctp.h
 create mode 100644 include/uapi/linux/mctp.h
 create mode 100644 net/mctp/Kconfig
 create mode 100644 net/mctp/Makefile
 create mode 100644 net/mctp/af_mctp.c
 create mode 100644 net/mctp/device.c
 create mode 100644 net/mctp/neigh.c
 create mode 100644 net/mctp/route.c

-- 
2.30.2



Jeremy Kerr (10):
  mctp: Add MCTP base
  mctp: Add base socket/protocol definitions
  mctp: Add base packet definitions
  mctp: Add sockaddr_mctp to uapi
  mctp: Add initial driver infrastructure
  mctp: Add device handling and netlink interface
  mctp: Add initial routing framework
  mctp: Populate socket implementation
  mctp: Implement message fragmentation & reassembly
  mctp: Add MCTP overview document

Matt Johnston (5):
  mctp: Add netlink route management
  mctp: Add neighbour implementation
  mctp: Add neighbour netlink interface
  mctp: Add dest neighbour lladdr to route output
  mctp: Allow per-netns default networks

 Documentation/networking/index.rst  |    1 +
 Documentation/networking/mctp.rst   |  213 ++++++
 MAINTAINERS                         |   12 +
 drivers/net/Kconfig                 |    2 +
 drivers/net/Makefile                |    1 +
 drivers/net/mctp/Kconfig            |    8 +
 drivers/net/mctp/Makefile           |    0
 include/linux/netdevice.h           |    4 +
 include/linux/socket.h              |    6 +-
 include/net/mctp.h                  |  231 ++++++
 include/net/mctpdevice.h            |   36 +
 include/net/net_namespace.h         |    4 +
 include/net/netns/mctp.h            |   36 +
 include/uapi/linux/if_arp.h         |    1 +
 include/uapi/linux/if_ether.h       |    3 +
 include/uapi/linux/if_link.h        |   10 +
 include/uapi/linux/mctp.h           |   36 +
 net/Kconfig                         |    1 +
 net/Makefile                        |    1 +
 net/core/sock.c                     |    1 +
 net/mctp/Kconfig                    |   13 +
 net/mctp/Makefile                   |    3 +
 net/mctp/af_mctp.c                  |  396 ++++++++++
 net/mctp/device.c                   |  423 +++++++++++
 net/mctp/neigh.c                    |  342 +++++++++
 net/mctp/route.c                    | 1099 +++++++++++++++++++++++++++
 net/socket.c                        |    1 +
 security/selinux/hooks.c            |    4 +-
 security/selinux/include/classmap.h |    4 +-
 29 files changed, 2889 insertions(+), 3 deletions(-)
 create mode 100644 Documentation/networking/mctp.rst
 create mode 100644 drivers/net/mctp/Kconfig
 create mode 100644 drivers/net/mctp/Makefile
 create mode 100644 include/net/mctp.h
 create mode 100644 include/net/mctpdevice.h
 create mode 100644 include/net/netns/mctp.h
 create mode 100644 include/uapi/linux/mctp.h
 create mode 100644 net/mctp/Kconfig
 create mode 100644 net/mctp/Makefile
 create mode 100644 net/mctp/af_mctp.c
 create mode 100644 net/mctp/device.c
 create mode 100644 net/mctp/neigh.c
 create mode 100644 net/mctp/route.c

-- 
2.30.2


Jeremy Kerr (10):
  mctp: Add MCTP base
  mctp: Add base socket/protocol definitions
  mctp: Add base packet definitions
  mctp: Add sockaddr_mctp to uapi
  mctp: Add initial driver infrastructure
  mctp: Add device handling and netlink interface
  mctp: Add initial routing framework
  mctp: Populate socket implementation
  mctp: Implement message fragmentation & reassembly
  mctp: Add MCTP overview document

Matt Johnston (5):
  mctp: Add netlink route management
  mctp: Add neighbour implementation
  mctp: Add neighbour netlink interface
  mctp: Add dest neighbour lladdr to route output
  mctp: Allow per-netns default networks

 Documentation/networking/index.rst  |    1 +
 Documentation/networking/mctp.rst   |  213 ++++++
 MAINTAINERS                         |   12 +
 drivers/net/Kconfig                 |    2 +
 drivers/net/Makefile                |    1 +
 drivers/net/mctp/Kconfig            |    8 +
 drivers/net/mctp/Makefile           |    0
 include/linux/netdevice.h           |    4 +
 include/linux/socket.h              |    6 +-
 include/net/mctp.h                  |  231 ++++++
 include/net/mctpdevice.h            |   36 +
 include/net/net_namespace.h         |    4 +
 include/net/netns/mctp.h            |   36 +
 include/uapi/linux/if_arp.h         |    1 +
 include/uapi/linux/if_ether.h       |    3 +
 include/uapi/linux/if_link.h        |   10 +
 include/uapi/linux/mctp.h           |   36 +
 net/Kconfig                         |    1 +
 net/Makefile                        |    1 +
 net/core/sock.c                     |    1 +
 net/mctp/Kconfig                    |   13 +
 net/mctp/Makefile                   |    3 +
 net/mctp/af_mctp.c                  |  396 ++++++++++
 net/mctp/device.c                   |  423 +++++++++++
 net/mctp/neigh.c                    |  342 +++++++++
 net/mctp/route.c                    | 1099 +++++++++++++++++++++++++++
 net/socket.c                        |    1 +
 security/selinux/hooks.c            |    4 +-
 security/selinux/include/classmap.h |    4 +-
 29 files changed, 2889 insertions(+), 3 deletions(-)
 create mode 100644 Documentation/networking/mctp.rst
 create mode 100644 drivers/net/mctp/Kconfig
 create mode 100644 drivers/net/mctp/Makefile
 create mode 100644 include/net/mctp.h
 create mode 100644 include/net/mctpdevice.h
 create mode 100644 include/net/netns/mctp.h
 create mode 100644 include/uapi/linux/mctp.h
 create mode 100644 net/mctp/Kconfig
 create mode 100644 net/mctp/Makefile
 create mode 100644 net/mctp/af_mctp.c
 create mode 100644 net/mctp/device.c
 create mode 100644 net/mctp/neigh.c
 create mode 100644 net/mctp/route.c

-- 
2.30.2

[PATCH net-next v4 15/15] mctp: Add MCTP overview document

[Jeremy Kerr]

This change adds a brief document about the sockets API provided for
sending and receiving MCTP messages from userspace.

This is roughly based on the OpenBMC design document, at:

  https://github.com/openbmc/docs/blob/master/designs/mctp/mctp-kernel.md

Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>

---
v2:
 - Controller -> component
---
 Documentation/networking/index.rst |   1 +
 Documentation/networking/mctp.rst  | 213 +++++++++++++++++++++++++++++
 MAINTAINERS                        |   1 +
 3 files changed, 215 insertions(+)
 create mode 100644 Documentation/networking/mctp.rst

diff --git a/Documentation/networking/index.rst b/Documentation/networking/index.rst
index a91a2739f8ed..58bc8cd367c6 100644
--- a/Documentation/networking/index.rst
+++ b/Documentation/networking/index.rst
@@ -69,6 +69,7 @@ Contents:
    l2tp
    lapb-module
    mac80211-injection
+   mctp
    mpls-sysctl
    mptcp-sysctl
    multiqueue
diff --git a/Documentation/networking/mctp.rst b/Documentation/networking/mctp.rst
new file mode 100644
index 000000000000..6100cdc220f6
--- /dev/null
+++ b/Documentation/networking/mctp.rst
@@ -0,0 +1,213 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==============================================
+Management Component Transport Protocol (MCTP)
+==============================================
+
+net/mctp/ contains protocol support for MCTP, as defined by DMTF standard
+DSP0236. Physical interface drivers ("bindings" in the specification) are
+provided in drivers/net/mctp/.
+
+The core code provides a socket-based interface to send and receive MCTP
+messages, through an AF_MCTP, SOCK_DGRAM socket.
+
+Structure: interfaces & networks
+================================
+
+The kernel models the local MCTP topology through two items: interfaces and
+networks.
+
+An interface (or "link") is an instance of an MCTP physical transport binding
+(as defined by DSP0236, section 3.2.47), likely connected to a specific hardware
+device. This is represented as a ``struct netdevice``.
+
+A network defines a unique address space for MCTP endpoints by endpoint-ID
+(described by DSP0236, section 3.2.31). A network has a user-visible identifier
+to allow references from userspace. Route definitions are specific to one
+network.
+
+Interfaces are associated with one network. A network may be associated with one
+or more interfaces.
+
+If multiple networks are present, each may contain endpoint IDs (EIDs) that are
+also present on other networks.
+
+Sockets API
+===========
+
+Protocol definitions
+--------------------
+
+MCTP uses ``AF_MCTP`` / ``PF_MCTP`` for the address- and protocol- families.
+Since MCTP is message-based, only ``SOCK_DGRAM`` sockets are supported.
+
+.. code-block:: C
+
+    int sd = socket(AF_MCTP, SOCK_DGRAM, 0);
+
+The only (current) value for the ``protocol`` argument is 0.
+
+As with all socket address families, source and destination addresses are
+specified with a ``sockaddr`` type, with a single-byte endpoint address:
+
+.. code-block:: C
+
+    typedef __u8		mctp_eid_t;
+
+    struct mctp_addr {
+            mctp_eid_t		s_addr;
+    };
+
+    struct sockaddr_mctp {
+            unsigned short int	smctp_family;
+            int			smctp_network;
+            struct mctp_addr	smctp_addr;
+            __u8		smctp_type;
+            __u8		smctp_tag;
+    };
+
+    #define MCTP_NET_ANY	0x0
+    #define MCTP_ADDR_ANY	0xff
+
+
+Syscall behaviour
+-----------------
+
+The following sections describe the MCTP-specific behaviours of the standard
+socket system calls. These behaviours have been chosen to map closely to the
+existing sockets APIs.
+
+``bind()`` : set local socket address
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Sockets that receive incoming request packets will bind to a local address,
+using the ``bind()`` syscall.
+
+.. code-block:: C
+
+    struct sockaddr_mctp addr;
+
+    addr.smctp_family = AF_MCTP;
+    addr.smctp_network = MCTP_NET_ANY;
+    addr.smctp_addr.s_addr = MCTP_ADDR_ANY;
+    addr.smctp_type = MCTP_TYPE_PLDM;
+    addr.smctp_tag = MCTP_TAG_OWNER;
+
+    int rc = bind(sd, (struct sockaddr *)&addr, sizeof(addr));
+
+This establishes the local address of the socket. Incoming MCTP messages that
+match the network, address, and message type will be received by this socket.
+The reference to 'incoming' is important here; a bound socket will only receive
+messages with the TO bit set, to indicate an incoming request message, rather
+than a response.
+
+The ``smctp_tag`` value will configure the tags accepted from the remote side of
+this socket. Given the above, the only valid value is ``MCTP_TAG_OWNER``, which
+will result in remotely "owned" tags being routed to this socket. Since
+``MCTP_TAG_OWNER`` is set, the 3 least-significant bits of ``smctp_tag`` are not
+used; callers must set them to zero.
+
+A ``smctp_network`` value of ``MCTP_NET_ANY`` will configure the socket to
+receive incoming packets from any locally-connected network. A specific network
+value will cause the socket to only receive incoming messages from that network.
+
+The ``smctp_addr`` field specifies a local address to bind to. A value of
+``MCTP_ADDR_ANY`` configures the socket to receive messages addressed to any
+local destination EID.
+
+The ``smctp_type`` field specifies which message types to receive. Only the
+lower 7 bits of the type is matched on incoming messages (ie., the
+most-significant IC bit is not part of the match). This results in the socket
+receiving packets with and without a message integrity check footer.
+
+``sendto()``, ``sendmsg()``, ``send()`` : transmit an MCTP message
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+An MCTP message is transmitted using one of the ``sendto()``, ``sendmsg()`` or
+``send()`` syscalls. Using ``sendto()`` as the primary example:
+
+.. code-block:: C
+
+    struct sockaddr_mctp addr;
+    char buf[14];
+    ssize_t len;
+
+    /* set message destination */
+    addr.smctp_family = AF_MCTP;
+    addr.smctp_network = 0;
+    addr.smctp_addr.s_addr = 8;
+    addr.smctp_tag = MCTP_TAG_OWNER;
+    addr.smctp_type = MCTP_TYPE_ECHO;
+
+    /* arbitrary message to send, with message-type header */
+    buf[0] = MCTP_TYPE_ECHO;
+    memcpy(buf + 1, "hello, world!", sizeof(buf) - 1);
+
+    len = sendto(sd, buf, sizeof(buf), 0,
+                    (struct sockaddr_mctp *)&addr, sizeof(addr));
+
+The network and address fields of ``addr`` define the remote address to send to.
+If ``smctp_tag`` has the ``MCTP_TAG_OWNER``, the kernel will ignore any bits set
+in ``MCTP_TAG_VALUE``, and generate a tag value suitable for the destination
+EID. If ``MCTP_TAG_OWNER`` is not set, the message will be sent with the tag
+value as specified. If a tag value cannot be allocated, the system call will
+report an errno of ``EAGAIN``.
+
+The application must provide the message type byte as the first byte of the
+message buffer passed to ``sendto()``. If a message integrity check is to be
+included in the transmitted message, it must also be provided in the message
+buffer, and the most-significant bit of the message type byte must be 1.
+
+The ``sendmsg()`` system call allows a more compact argument interface, and the
+message buffer to be specified as a scatter-gather list. At present no ancillary
+message types (used for the ``msg_control`` data passed to ``sendmsg()``) are
+defined.
+
+Transmitting a message on an unconnected socket with ``MCTP_TAG_OWNER``
+specified will cause an allocation of a tag, if no valid tag is already
+allocated for that destination. The (destination-eid,tag) tuple acts as an
+implicit local socket address, to allow the socket to receive responses to this
+outgoing message. If any previous allocation has been performed (to for a
+different remote EID), that allocation is lost.
+
+Sockets will only receive responses to requests they have sent (with TO=1) and
+may only respond (with TO=0) to requests they have received.
+
+``recvfrom()``, ``recvmsg()``, ``recv()`` : receive an MCTP message
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+An MCTP message can be received by an application using one of the
+``recvfrom()``, ``recvmsg()``, or ``recv()`` system calls. Using ``recvfrom()``
+as the primary example:
+
+.. code-block:: C
+
+    struct sockaddr_mctp addr;
+    socklen_t addrlen;
+    char buf[14];
+    ssize_t len;
+
+    addrlen = sizeof(addr);
+
+    len = recvfrom(sd, buf, sizeof(buf), 0,
+                    (struct sockaddr_mctp *)&addr, &addrlen);
+
+    /* We can expect addr to describe an MCTP address */
+    assert(addrlen >= sizeof(buf));
+    assert(addr.smctp_family == AF_MCTP);
+
+    printf("received %zd bytes from remote EID %d\n", rc, addr.smctp_addr);
+
+The address argument to ``recvfrom`` and ``recvmsg`` is populated with the
+remote address of the incoming message, including tag value (this will be needed
+in order to reply to the message).
+
+The first byte of the message buffer will contain the message type byte. If an
+integrity check follows the message, it will be included in the received buffer.
+
+The ``recv()`` system call behaves in a similar way, but does not provide a
+remote address to the application. Therefore, these are only useful if the
+remote address is already known, or the message does not require a reply.
+
+Like the send calls, sockets will only receive responses to requests they have
+sent (TO=1) and may only respond (TO=0) to requests they have received.
diff --git a/MAINTAINERS b/MAINTAINERS
index 4ca73465e690..73beb91891ee 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11037,6 +11037,7 @@ M:	Jeremy Kerr <jk@codeconstruct.com.au>
 M:	Matt Johnston <matt@codeconstruct.com.au>
 L:	netdev@vger.kernel.org
 S:	Maintained
+F:	Documentation/networking/mctp.rst
 F:	drivers/net/mctp/
 F:	include/net/mctp.h
 F:	include/net/mctpdevice.h
-- 
2.30.2

Re: [PATCH net-next v4 00/15] Add Management Component Transport Protocol support

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (refs/heads/master):

On Thu, 29 Jul 2021 10:20:38 +0800 you wrote:
> This series adds core MCTP support to the kernel. From the Kconfig
> description:
> 
>   Management Component Transport Protocol (MCTP) is an in-system
>   protocol for communicating between management controllers and
>   their managed devices (peripherals, host processors, etc.). The
>   protocol is defined by DMTF specification DSP0236.
> 
> [...]

Here is the summary with links:
  - [net-next,v4,01/15] mctp: Add MCTP base
    https://git.kernel.org/netdev/net-next/c/bc49d8169aa7
  - [net-next,v4,02/15] mctp: Add base socket/protocol definitions
    https://git.kernel.org/netdev/net-next/c/8f601a1e4f8c
  - [net-next,v4,03/15] mctp: Add base packet definitions
    https://git.kernel.org/netdev/net-next/c/2c8e2e9aec79
  - [net-next,v4,04/15] mctp: Add sockaddr_mctp to uapi
    https://git.kernel.org/netdev/net-next/c/60fc63981693
  - [net-next,v4,05/15] mctp: Add initial driver infrastructure
    https://git.kernel.org/netdev/net-next/c/4b2e69305cbb
  - [net-next,v4,06/15] mctp: Add device handling and netlink interface
    https://git.kernel.org/netdev/net-next/c/583be982d934
  - [net-next,v4,07/15] mctp: Add initial routing framework
    https://git.kernel.org/netdev/net-next/c/889b7da23abf
  - [net-next,v4,08/15] mctp: Add netlink route management
    https://git.kernel.org/netdev/net-next/c/06d2f4c583a7
  - [net-next,v4,09/15] mctp: Add neighbour implementation
    https://git.kernel.org/netdev/net-next/c/4d8b9319282a
  - [net-next,v4,10/15] mctp: Add neighbour netlink interface
    https://git.kernel.org/netdev/net-next/c/831119f88781
  - [net-next,v4,11/15] mctp: Populate socket implementation
    https://git.kernel.org/netdev/net-next/c/833ef3b91de6
  - [net-next,v4,12/15] mctp: Implement message fragmentation & reassembly
    https://git.kernel.org/netdev/net-next/c/4a992bbd3650
  - [net-next,v4,13/15] mctp: Add dest neighbour lladdr to route output
    https://git.kernel.org/netdev/net-next/c/26ab3fcaf235
  - [net-next,v4,14/15] mctp: Allow per-netns default networks
    https://git.kernel.org/netdev/net-next/c/03f2bbc4ee57
  - [net-next,v4,15/15] mctp: Add MCTP overview document
    https://git.kernel.org/netdev/net-next/c/6a2d98b18900

You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

Re: [PATCH net-next v4 15/15] mctp: Add MCTP overview document

[Eugene Syromiatnikov]

On Thu, Jul 29, 2021 at 10:20:53AM +0800, Jeremy Kerr wrote:
> This change adds a brief document about the sockets API provided for
> sending and receiving MCTP messages from userspace.

[...]

> diff --git a/Documentation/networking/mctp.rst b/Documentation/networking/mctp.rst

[...]

> +``bind()`` : set local socket address
> +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> +
> +Sockets that receive incoming request packets will bind to a local address,
> +using the ``bind()`` syscall.
> +
> +.. code-block:: C
> +
> +    struct sockaddr_mctp addr;
> +
> +    addr.smctp_family = AF_MCTP;
> +    addr.smctp_network = MCTP_NET_ANY;
> +    addr.smctp_addr.s_addr = MCTP_ADDR_ANY;
> +    addr.smctp_type = MCTP_TYPE_PLDM;

[...]

> +``sendto()``, ``sendmsg()``, ``send()`` : transmit an MCTP message
> +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> +
> +An MCTP message is transmitted using one of the ``sendto()``, ``sendmsg()`` or
> +``send()`` syscalls. Using ``sendto()`` as the primary example:
> +
> +.. code-block:: C
> +
> +    struct sockaddr_mctp addr;
> +    char buf[14];
> +    ssize_t len;
> +
> +    /* set message destination */
> +    addr.smctp_family = AF_MCTP;
> +    addr.smctp_network = 0;
> +    addr.smctp_addr.s_addr = 8;
> +    addr.smctp_tag = MCTP_TAG_OWNER;
> +    addr.smctp_type = MCTP_TYPE_ECHO;

While MCTP_TYPE_PLDM and MCTP_TYPE_ECHO are mentioned
in the documentation, their definition is currently missing in the UAPI
header (or anywhere in the source tree at all).  Is that expected?