mptcp: add mptcpi_subflows_total counter

If the initial subflow has been removed, we cannot know without checking
other counters, e.g. ss -ti <filter> | grep -c tcp-ulp-mptcp or
getsockopt(SOL_MPTCP, MPTCP_FULL_INFO, ...) (or others except MPTCP_INFO
of course) and then check mptcp_subflow_data->num_subflows to get the
total amount of subflows.

This patch adds a new counter mptcpi_subflows_total in mptcpi_flags to
store the total amount of subflows, including the initial one. A new
helper __mptcp_has_initial_subflow() is added to check whether the
initial subflow has been removed or not. With this helper, we can then
compute the total amount of subflows from mptcp_info by doing something
like:

mptcpi_subflows_total = mptcpi_subflows +
__mptcp_has_initial_subflow(msk).

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/428
Reviewed-by: Matthieu Baerts <matttbe@kernel.org>
Signed-off-by: Geliang Tang <geliang.tang@suse.com>
Signed-off-by: Mat Martineau <martineau@kernel.org>
Link: https://lore.kernel.org/r/20231128-send-net-next-2023107-v4-1-8d6b94150f6b@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

doc/netlink: Update schema to support cmd-cnt-name and cmd-max-name

allow specifying cmd-cnt-name and cmd-max-name in netlink specs, in
accordance with Documentation/userspace-api/netlink/c-code-gen.rst.

Use cmd-cnt-name and attr-cnt-name in the mptcp yaml spec and in the
corresponding uAPI headers, to preserve the #defines we had in the past
and avoid adding new ones.

v2:
- squash modification in mptcp.yaml and MPTCP uAPI headers

Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Link: https://lore.kernel.org/r/12d4ed0116d8883cf4b533b856f3125a34e56749.1698415310.git.dcaratti@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

uapi: mptcp: use header file generated from YAML spec

generated with:

$ ./tools/net/ynl/ynl-gen-c.py --mode uapi \
> --spec Documentation/netlink/specs/mptcp.yaml \
> --header -o include/uapi/linux/mptcp_pm.h

Link: https://github.com/multipath-tcp/mptcp_net-next/issues/340
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: Mat Martineau <martineau@kernel.org>
Link: https://lore.kernel.org/r/20231023-send-net-next-20231023-1-v2-5-16b1f701f900@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: mptcp: convert netlink from small_ops to ops

in the current MPTCP control plane, all operations use a netlink
attribute of the same type "MPTCP_PM_ATTR". However, add/del/get/flush
operations only parse the first element in the message _ the one that
describes MPTCP endpoints (that was named MPTCP_PM_ATTR_ADDR and
mostly used in ADD_ADDR operations _ probably the similarity of "attr",
"addr" and "add" might cause some confusion to human readers).
Convert MPTCP from 'small_ops' to 'ops', thus allowing different attributes
for each single operation, hopefully makes all this clearer to human
readers.

- use a separate attribute set for add/del/get/flush address operation,
binary compatible with the existing one, to store the endpoint address.
MPTCP_PM_ENDPOINT_ADDR is added to the uAPI (with the same value as
MPTCP_PM_ATTR_ADDR) for these operations.
- convert mptcp_pm_ops[] and add policy files accordingly.

this prepares MPTCP control plane to be described as YAML spec.

Link: https://github.com/multipath-tcp/mptcp_net-next/issues/340
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: Mat Martineau <martineau@kernel.org>
Link: https://lore.kernel.org/r/20231023-send-net-next-20231023-1-v2-3-16b1f701f900@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

mptcp: introduce MPTCP_FULL_INFO getsockopt

Some user-space applications want to monitor the subflows utilization.

Dumping the per subflow tcp_info is not enough, as the PM could close
and re-create the subflows under-the-hood, fooling the accounting.
Even checking the src/dst addresses used by each subflow could not
be enough, because new subflows could re-use the same address/port of
the just closed one.

This patch introduces a new socket option, allow dumping all the relevant
information all-at-once (everything, everywhere...), in a consistent
manner.

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/388
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

mptcp: track some aggregate data counters

Currently there are no data transfer counters accounting for all
the subflows used by a given MPTCP socket. The user-space can compute
such figures aggregating the subflow info, but that is inaccurate
if any subflow is closed before the MPTCP socket itself.

Add the new counters in the MPTCP socket itself and expose them
via the existing diag and sockopt. While touching mptcp_diag_fill_info(),
acquire the relevant locks before fetching the msk data, to ensure
better data consistency

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/385
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

mptcp: add pm listener events

This patch adds two new MPTCP netlink event types for PM listening
socket create and close, named MPTCP_EVENT_LISTENER_CREATED and
MPTCP_EVENT_LISTENER_CLOSED.

Add a new function mptcp_event_pm_listener() to push the new events
with family, port and addr to userspace.

Invoke mptcp_event_pm_listener() with MPTCP_EVENT_LISTENER_CREATED in
mptcp_listen() and mptcp_pm_nl_create_listen_socket(), invoke it with
MPTCP_EVENT_LISTENER_CLOSED in __mptcp_close_ssk().

Signed-off-by: Geliang Tang <geliang.tang@suse.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

mptcp: fix conflict with <netinet/in.h>

Including <linux/mptcp.h> before the C library <netinet/in.h> header
causes symbol redefinition errors at compile-time due to duplicate
declarations and definitions in the <linux/in.h> header included by
<linux/mptcp.h>.

Explicitly include <netinet/in.h> before <linux/in.h> in
<linux/mptcp.h> when __KERNEL__ is not defined so that the C library
compatibility logic in <linux/libc-compat.h> is enabled when including
<linux/mptcp.h> in user space code.

Fixes: c11c5906bc0a ("mptcp: add MPTCP_SUBFLOW_ADDRS getsockopt support")
Signed-off-by: Ossama Othman <ossama.othman@intel.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

mptcp: netlink: allow userspace-driven subflow establishment

This allows userspace to tell kernel to add a new subflow to an existing
mptcp connection.

Userspace provides the token to identify the mptcp-level connection
that needs a change in active subflows and the local and remote
addresses of the new or the to-be-removed subflow.

MPTCP_PM_CMD_SUBFLOW_CREATE requires the following parameters:
{ token, { loc_id, family, loc_addr4 | loc_addr6 }, { family, rem_addr4 |
rem_addr6, rem_port }

MPTCP_PM_CMD_SUBFLOW_DESTROY requires the following parameters:
{ token, { family, loc_addr4 | loc_addr6, loc_port }, { family, rem_addr4 |
rem_addr6, rem_port }

Acked-by: Paolo Abeni <pabeni@redhat.com>
Co-developed-by: Kishen Maloor <kishen.maloor@intel.com>
Signed-off-by: Kishen Maloor <kishen.maloor@intel.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

mptcp: netlink: Add MPTCP_PM_CMD_REMOVE

This change adds a MPTCP netlink command for issuing a
REMOVE_ADDR signal for an address over the chosen MPTCP
connection from a userspace path manager.

The command requires the following parameters: {token, loc_id}.

Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Kishen Maloor <kishen.maloor@intel.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

mptcp: netlink: Add MPTCP_PM_CMD_ANNOUNCE

This change adds a MPTCP netlink interface for issuing
ADD_ADDR advertisements over the chosen MPTCP connection from a
userspace path manager.

The command requires the following parameters:
{ token, { loc_id, family, daddr4 | daddr6 [, dport] } [, if_idx],
flags[signal] }.

Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Kishen Maloor <kishen.maloor@intel.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

mptcp: expose server_side attribute in MPTCP netlink events

This change records the 'server_side' attribute of MPTCP_EVENT_CREATED
and MPTCP_EVENT_ESTABLISHED events to inform their recipient about the
Client/Server role of the running MPTCP application.

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/246
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Kishen Maloor <kishen.maloor@intel.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

mptcp: introduce implicit endpoints

In some edge scenarios, an MPTCP subflows can use a local address
mapped by a "implicit" endpoint created by the in-kernel path manager.

Such endpoints presence can be confusing, as it's creation is hard
to track and will prevent the later endpoint creation from the user-space
using the same address.

Define a new endpoint flag to mark implicit endpoints and allow the
user-space to replace implicit them with user-provided data at endpoint
creation time.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

mptcp: add missing documented NL params

'loc_id' and 'rem_id' are set in all events linked to subflows but those
were missing in the events description in the comments.

Fixes: b911c97c7dc7 ("mptcp: add netlink event support")
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

mptcp: add MPTCP_SUBFLOW_ADDRS getsockopt support

This retrieves the address pairs of all subflows currently
active for a given mptcp connection.

It re-uses the same meta-header as for MPTCP_TCPINFO.

A new structure is provided to hold the subflow
address data:

struct mptcp_subflow_addrs {
union {
__kernel_sa_family_t sa_family;
struct sockaddr sa_local;
struct sockaddr_in sin_local;
struct sockaddr_in6 sin6_local;
struct sockaddr_storage ss_local;
};
union {
struct sockaddr sa_remote;
struct sockaddr_in sin_remote;
struct sockaddr_in6 sin6_remote;
struct sockaddr_storage ss_remote;
};
};

Usage of the new getsockopt is very similar to
MPTCP_TCPINFO one.

Userspace allocates a
'struct mptcp_subflow_data', followed by one or
more 'struct mptcp_subflow_addrs', then inits the
mptcp_subflow_data structure as follows:

struct mptcp_subflow_addrs *sf_addr;
struct mptcp_subflow_data *addr;
socklen_t olen = sizeof(*addr) + (8 * sizeof(*sf_addr));

addr = malloc(olen);
addr->size_subflow_data = sizeof(*addr);
addr->num_subflows = 0;
addr->size_kernel = 0;
addr->size_user = sizeof(struct mptcp_subflow_addrs);

sf_addr = (struct mptcp_subflow_addrs *)(addr + 1);

and then retrieves the endpoint addresses via:
ret = getsockopt(fd, SOL_MPTCP, MPTCP_SUBFLOW_ADDRS,
addr, &olen);

If the call succeeds, kernel will have added up to 8
endpoint addresses after the 'mptcp_subflow_data' header.

Userspace needs to re-check 'olen' value to detect how
many bytes have been filled in by the kernel.

Userspace can check addr->num_subflows to discover when
there were more subflows that available data space.

Co-developed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

mptcp: add MPTCP_TCPINFO getsockopt support

Allow users to retrieve TCP_INFO data of all subflows.

Users need to pre-initialize a meta header that has to be
prepended to the data buffer that will be filled with the tcp info data.

The meta header looks like this:

struct mptcp_subflow_data {
__u32 size_subflow_data;/* size of this structure in userspace */
__u32 num_subflows; /* must be 0, set by kernel */
__u32 size_kernel; /* must be 0, set by kernel */
__u32 size_user; /* size of one element in data[] */
} __attribute__((aligned(8)));

size_subflow_data has to be set to 'sizeof(struct mptcp_subflow_data)'.
This allows to extend mptcp_subflow_data structure later on without
breaking backwards compatibility.

If the structure is extended later on, kernel knows where the
userspace-provided meta header ends, even if userspace uses an older
(smaller) version of the structure.

num_subflows must be set to 0. If the getsockopt request succeeds (return
value is 0), it will be updated to contain the number of active subflows
for the given logical connection.

size_kernel must be set to 0. If the getsockopt request is successful,
it will contain the size of the 'struct tcp_info' as known by the kernel.
This is informational only.

size_user must be set to 'sizeof(struct tcp_info)'.

This allows the kernel to only fill in the space reserved/expected by
userspace.

Example:

struct my_tcp_info {
struct mptcp_subflow_data d;
struct tcp_info ti[2];
};
struct my_tcp_info ti;
socklen_t olen;

memset(&ti, 0, sizeof(ti));

ti.d.size_subflow_data = sizeof(struct mptcp_subflow_data);
ti.d.size_user = sizeof(struct tcp_info);
olen = sizeof(ti);

ret = getsockopt(fd, SOL_MPTCP, MPTCP_TCPINFO, &ti, &olen);
if (ret < 0)
die_perror("getsockopt MPTCP_TCPINFO");

mptcp_subflow_data.num_subflows is populated with the number of
subflows that exist on the kernel side for the logical mptcp connection.

This allows userspace to re-try with a larger tcp_info array if the number
of subflows was larger than the available space in the ti[] array.

olen has to be set to the number of bytes that userspace has allocated to
receive the kernel data. It will be updated to contain the real number
bytes that have been copied to by the kernel.

In the above example, if the number if subflows was 1, olen is equal to
'sizeof(struct mptcp_subflow_data) + sizeof(struct tcp_info).
For 2 or more subflows olen is equal to 'sizeof(struct my_tcp_info)'.

If there was more data that could not be copied due to lack of space
in the option buffer, userspace can detect this by checking
mptcp_subflow_data->num_subflows.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

mptcp: add MPTCP_INFO getsockopt

Its not compatible with multipath-tcp.org kernel one.

1. The out-of-tree implementation defines a different 'struct mptcp_info',
with embedded __user addresses for additional data such as
endpoint addresses.

2. Mat Martineau points out that embedded __user addresses doesn't work
with BPF_CGROUP_RUN_PROG_GETSOCKOPT() which assumes that copying in
optsize bytes from optval provides all data that got copied to userspace.

This provides mptcp_info data for the given mptcp socket.

Userspace sets optlen to the size of the structure it expects.
The kernel updates it to contain the number of bytes that it copied.

This allows to append more information to the structure later.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

mptcp: remote addresses fullmesh

This patch added and managed a new per endpoint flag, named
MPTCP_PM_ADDR_FLAG_FULLMESH.

In mptcp_pm_create_subflow_or_signal_addr(), if such flag is set, instead
of:
remote_address((struct sock_common *)sk, &remote);
fill a temporary allocated array of all known remote address. After
releaseing the pm lock loop on such array and create a subflow for each
remote address from the given local.

Note that the we could still use an array even for non 'fullmesh'
endpoint: with a single entry corresponding to the primary MPC subflow
remote address.

Suggested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Geliang Tang <geliangtang@xiaomi.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

mptcp: add csum_enabled in mptcp_sock

This patch added a new member named csum_enabled in struct mptcp_sock,
used a dummy mptcp_is_checksum_enabled() helper to initialize it.

Also added a new member named mptcpi_csum_enabled in struct mptcp_info
to expose the csum_enabled flag.

Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

mptcp: add mptcp reset option support

The MPTCP reset option allows to carry a mptcp-specific error code that
provides more information on the nature of a connection reset.

Reset option data received gets stored in the subflow context so it can
be sent to userspace via the 'subflow closed' netlink event.

When a subflow is closed, the desired error code that should be sent to
the peer is also placed in the subflow context structure.

If a reset is sent before subflow establishment could complete, e.g. on
HMAC failure during an MP_JOIN operation, the mptcp skb extension is
used to store the reset information.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

mptcp: add local addr info in mptcp_info

Add mptcpi_local_addr_used and mptcpi_local_addr_max in struct mptcp_info.

Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

mptcp: add netlink event support

Allow userspace (mptcpd) to subscribe to mptcp genl multicast events.
This implementation reuses the same event API as the mptcp kernel fork
to ease integration of existing tools, e.g. mptcpd.

Supported events include:
1. start and close of an mptcp connection
2. start and close of subflows (joins)
3. announce and withdrawals of addresses
4. subflow priority (backup/non-backup) change.

Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

mptcp: add set_flags command in PM netlink

This patch added a new command MPTCP_PM_CMD_SET_FLAGS in PM netlink:

In mptcp_nl_cmd_set_flags, parse the input address, get the backup value
according to whether the address's FLAG_BACKUP flag is set from the
user-space. Then check whether this address had been added in the local
address list. If it had been, then call mptcp_nl_addr_backup to deal with
this address.

In mptcp_nl_addr_backup, traverse all the existing msk sockets to find
the relevant sockets, and call mptcp_pm_nl_mp_prio_send_ack to send out
a MP_PRIO ACK packet.

Finally in mptcp_nl_cmd_set_flags, set or clear the address's FLAG_BACKUP
flag.

Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

mptcp: add MPTCP socket diag interface

exposes basic inet socket attribute, plus some MPTCP socket
fields comprising PM status and MPTCP-level sequence numbers.

Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

mptcp: add netlink-based PM

Expose a new netlink family to userspace to control the PM, setting:

- list of local addresses to be signalled.
- list of local addresses used to created subflows.
- maximum number of add_addr option to react

When the msk is fully established, the PM netlink attempts to
announce the 'signal' list via the ADD_ADDR option. Since we
currently lack the ADD_ADDR echo (and related event) only the
first addr is sent.

After exhausting the 'announce' list, the PM tries to create
subflow for each addr in 'local' list, waiting for each
connection to be completed before attempting the next one.

Idea is to add an additional PM hook for ADD_ADDR echo, to allow
the PM netlink announcing multiple addresses, in sequence.

Co-developed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

mptcp: allow dumping subflow context to userspace

add ulp-specific diagnostic functions, so that subflow information can be
dumped to userspace programs like 'ss'.

v2 -> v3:
- uapi: use bit macros appropriate for userspace

Co-developed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Co-developed-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>