When the worker moves some bytes from the OoO queue into
the receive queue, the msk->ask_seq is updated, the MPTCP-level
ack carrying that value needs to wait the next ingress packet,
possibly slowing down or hanging the peer
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

Before sending 'x' new bytes also check that the new snd_una would
be within the permitted receive window.

For every ACK that also contains a DSS ack, check whether its tcp-level
receive window would advance the current mptcp window right edge and
update it if so.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Co-developed-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

MPTCP maintains a status bit, MPTCP_SEND_SPACE, that is set when at
least one subflow and the mptcp socket itself are writeable.

mptcp_poll returns EPOLLOUT if the bit is set.

mptcp_sendmsg makes sure MPTCP_SEND_SPACE gets cleared when last write
has used up all subflows or the mptcp socket wmem.

This reworks nospace handling as follows:

MPTCP_SEND_SPACE is replaced with MPTCP_NOSPACE, i.e. inverted meaning.
This bit is set when the mptcp socket is not writeable.
The mptcp-level ack path schedule will then schedule the mptcp worker
to allow it to free already-acked data (and reduce wmem usage).

This will then wake userspace processes that wait for a POLLOUT event.

sendmsg will set MPTCP_NOSPACE only when it has to wait for more
wmem (blocking I/O case).

poll path will set MPTCP_NOSPACE in case the mptcp socket is
not writeable.

Normal tcp-level notification (SOCK_NOSPACE) is only enabled
in case the subflow socket has no available wmem.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

After the previous patch we may end-up with unsent data
in the write buffer. If such buffer is full, the writer
will block for unlimited time.

We need to trigger the MPTCP xmit path even for the
subflow rx path, on MPTCP snd_una updates.

Keep things simple and just schedule the work queue if
needed.
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

mptcp_sendmsg() is refactored so that first it copies
the data provided from user space into the send queue,
and then tries to spool the send queue via sendmsg_frag.

There a subtle change in the mptcp level collapsing on
consecutive data fragment: we now allow that only on unsent
data.

The latter don't need to deal with msghdr data anymore
and can be simplified in a relevant way.

snd_nxt and write_seq are now tracked independently.

Overall this allows some relevant cleanup and will
allow sending pending mptcp data on msk una update in
later patch.
Co-developed-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

We must not close the subflows before all the MPTCP level
data, comprising the DATA_FIN has been acked at the MPTCP
level, otherwise we could be unable to retransmit as needed.

__mptcp_wr_shutdown() shutdown is responsible to check for the
correct status and close all subflows. Is called by the output
path after spooling any data and at shutdown/close time.

In a similar way, __mptcp_destroy_sock() is responsible to clean-up
the MPTCP level status, and is called when the msk transition
to TCP_CLOSE.

The protocol level close() does not force anymore the TCP_CLOSE
status, but orphan the msk socket and all the subflows.
Orphaned msk sockets are forciby closed after a timeout or
when all MPTCP-level data is acked.

There is a caveat about keeping the orphaned subflows around:
the TCP stack can asynchronusly call tcp_cleanup_ulp() on them via
tcp_close(). To prevent accessing freed memory on later MPTCP
level operations, the msk acquires a reference to each subflow
socket and prevent subflow_ulp_release() from releasing the
subflow context before __mptcp_destroy_sock().

The additional subflow references are released by __mptcp_done()
and the async ULP release is detected checking ULP ops. If such
field has been already cleared by the ULP release path, the
dangling context is freed directly by __mptcp_done().
Co-developed-by: NDavide Caratti <dcaratti@redhat.com>
Signed-off-by: NDavide Caratti <dcaratti@redhat.com>
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

Track the next MPTCP sequence number used on xmit,
currently always equal to write_next.
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

Preparation patch to track the data pending in the msk
write queue. No functional change introduced here
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

The current argument list is pretty long and quite unreadable,
move many of them into a specific struct. Later patches
will add more stuff to such struct.

Additionally drop the 'timeo' argument, now unused.
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

remove some of code duplications an allow preventing
rescheduling on close.
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

mptcp_push_pending() is called even on orphaned
msk (and orphaned subflows), if there is outstanding
data at close() time.

To cope with the above MPTCP needs to handle explicitly
the allocation failure on xmit. The newly introduced
do_tcp_sendfrag() allows that, just plug it.

We can additionally drop a couple of sanity checks,
duplicate in the TCP code.
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

Fix the following Smatch complaint:

     net/mptcp/pm_netlink.c:213 mptcp_pm_add_timer()
     warn: variable dereferenced before check 'msk' (see line 208)

 net/mptcp/pm_netlink.c
    207          struct mptcp_sock *msk = entry->sock;
    208          struct sock *sk = (struct sock *)msk;
    209          struct net *net = sock_net(sk);
                                           ^^
 "msk" dereferenced here.

    210
    211          pr_debug("msk=%p", msk);
    212
    213          if (!msk)
                    ^^^^
 Too late.

    214                  return;
    215

Fixes: 93f323b9 ("mptcp: add a new sysctl add_addr_timeout")
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: NDan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: NGeliang Tang <geliangtang@gmail.com>
Link: https://lore.kernel.org/r/078a2ef5bdc4e3b2c25ef852461692001f426495.1604976945.git.geliangtang@gmail.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>

The mptcp proto struct currently does not provide the
required limit for forward memory scheduling. Under
pressure sk_rmem_schedule() will unconditionally try
to use such field and will oops.

Address the issue inheriting the tcp limit, as we already
do for the wmem one.

Fixes: 9c3f94e1 ("mptcp: add missing memory scheduling in the rx path")
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Reviewed-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Link: https://lore.kernel.org/r/37af798bd46f402fb7c79f57ebbdd00614f5d7fa.1604861097.git.pabeni@redhat.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>

This patch added a new sysctl, named add_addr_timeout, to control the
timeout value (in seconds) of the ADD_ADDR retransmission.
Suggested-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Suggested-by: NPaolo Abeni <pabeni@redhat.com>
Acked-by: NPaolo Abeni <pabeni@redhat.com>
Reviewed-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: NGeliang Tang <geliangtang@gmail.com>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

mptcp_clean_una() will wake writers in case memory could be reclaimed.
When called from mptcp_sendmsg the wakeup code isn't needed.

Move the wakeup to a new helper and then use that from the mptcp worker.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

When the TCP stack splits a packet on the write queue, the tail
half currently lose the associated skb extensions, and will not
carry the DSM on the wire.

The above does not cause functional problems and is allowed by
the RFC, but interact badly with GRO and RX coalescing, as possible
candidates for aggregation will carry different TCP options.

This change tries to improve the MPTCP behavior, propagating the
skb extensions on split.

Additionally, we must prevent the MPTCP stack from updating the
mapping after the split occur: that will both violate the RFC and
fool the reader.
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

The function is short and won't sleep, so this can use the _fast version.
Acked-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

In addition to tcp autotuning during read, it may also increase the
receive buffer in tcp_clamp_window().

In this case, mptcp should adjust its receive buffer size as well so
it can move all pending skbs from the subflow socket to the mptcp socket.

At this time, TCP can have more skbs ready for processing than what the
mptcp receive buffer size allows.

In the mptcp case, the receive window announced is based on the free
space of the mptcp parent socket instead of the individual subflows.

Following the subflow allows mptcp to grow its receive buffer.

This is especially noticeable for loopback traffic where two skbs are
enough to fill the initial receive window.

In mptcp_data_ready() we do not hold the mptcp socket lock, so modifying
mptcp_sk->sk_rcvbuf is racy.  Do it when moving skbs from subflow to
mptcp socket, both sockets are locked in this case.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

gcc complains about use of uninitialized 'num'. Fix it by doing the first
assignment of 'num' when the variable is declared.

Fixes: 96d890da ("mptcp: add msk interations helper")
Signed-off-by: NDavide Caratti <dcaratti@redhat.com>
Acked-by: NPaolo Abeni <pabeni@redhat.com>
Link: https://lore.kernel.org/r/49e20da5d467a73414d4294a8bd35e2cb1befd49.1604308087.git.dcaratti@redhat.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>

When moving the skbs from the subflow into the msk receive
queue, we must schedule there the required amount of memory.

Try to borrow the required memory from the subflow, if needed,
so that we leverage the existing TCP heuristic.

Fixes: 6771bfd9 ("mptcp: update mptcp ack sequence from work queue")
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Reviewed-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Link: https://lore.kernel.org/r/f6143a6193a083574f11b00dbf7b5ad151bc4ff4.1603810630.git.pabeni@redhat.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>

Like TCP, MPTCP cannot be compiled as a module. Obviously, MPTCP IPv6'
support also depends on CONFIG_IPV6. But not all functions from IPv6
code are exported.

To simplify the code and reduce modifications outside MPTCP, it was
decided from the beginning to support MPTCP with IPv6 only if
CONFIG_IPV6 was built inlined. That's also why CONFIG_MPTCP_IPV6 was
created. More modifications are needed to support CONFIG_IPV6=m.

Even if it was not explicit, until recently, we were forcing CONFIG_IPV6
to be built-in because we had "select IPV6" in Kconfig. Now that we have
"depends on IPV6", we have to explicitly set "IPV6=y" to force
CONFIG_IPV6 not to be built as a module.

In other words, we can now only have CONFIG_MPTCP_IPV6=y if
CONFIG_IPV6=y.

Note that the new dependency might hide the fact IPv6 is not supported
in MPTCP even if we have CONFIG_IPV6=m. But selecting IPV6 like we did
before was forcing it to be built-in while it was maybe not what the
user wants.
Reported-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Fixes: 010b430d ("mptcp: MPTCP_IPV6 should depend on IPV6 instead of selecting it")
Signed-off-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Link: https://lore.kernel.org/r/20201021105154.628257-1-matthieu.baerts@tessares.netSigned-off-by: NJakub Kicinski <kuba@kernel.org>

MPTCP_IPV6 selects IPV6, thus enabling an optional feature the user may
not want to enable.  Fix this by making MPTCP_IPV6 depend on IPV6, like
is done for all other IPv6 features.

Fixes: f870fa0b ("mptcp: Add MPTCP socket stubs")
Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Link: https://lore.kernel.org/r/20201020073839.29226-1-geert@linux-m68k.orgSigned-off-by: NJakub Kicinski <kuba@kernel.org>

MPTCP_KUNIT_TESTS selects MPTCP, thus enabling an optional feature the
user may not want to enable.  Fix this by making the test depend on
MPTCP instead.

Fixes: a00a5822 ("mptcp: move crypto test to KUNIT")
Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Link: https://lore.kernel.org/r/20201019113240.11516-1-geert@linux-m68k.orgSigned-off-by: NJakub Kicinski <kuba@kernel.org>

Move mptcp_options_received's port initialization from
mptcp_parse_option to mptcp_get_options, put it together with
the other fields initializations of mptcp_options_received.
Signed-off-by: NGeliang Tang <geliangtang@gmail.com>
Reviewed-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

Initialize mptcp_options_received's ahmac to zero, otherwise it
will be a random number when receiving ADD_ADDR suboption with echo-flag=1.

Fixes: 3df523ab ("mptcp: Add ADD_ADDR handling")
Signed-off-by: NGeliang Tang <geliangtang@gmail.com>
Reviewed-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

The msk can close MP_JOIN subflows if the initial handshake
fails. Currently such subflows are kept alive in the
conn_list until the msk itself is closed.

Beyond the wasted memory, we could end-up sending the
DATA_FIN and the DATA_FIN ack on such socket, even after a
reset.

Fixes: 43b54c6e ("mptcp: Use full MPTCP-level disconnect state machine")
Reviewed-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

Additional/MP_JOIN subflows that do not pass some initial handshake
tests currently causes fallback to TCP. That is an RFC violation:
we should instead reset the subflow and leave the the msk untouched.

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/91
Fixes: f296234c ("mptcp: Add handling of incoming MP_JOIN requests")
Reviewed-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

using packetdrill it's possible to observe the same MPTCP DSN being acked
by different subflows with DACK4 and DACK8. This is in contrast with what
specified in RFC8684 §3.3.2: if an MPTCP endpoint transmits a 64-bit wide
DSN, it MUST be acknowledged with a 64-bit wide DACK. Fix 'use_64bit_ack'
variable to make it a property of MPTCP sockets, not TCP subflows.

Fixes: a0c1d0ea ("mptcp: Use 32-bit DATA_ACK when possible")
Acked-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NDavide Caratti <dcaratti@redhat.com>
Reviewed-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

If recvmsg() and the workqueue race to dequeue the data
pending on some subflow, the current mapping for such
subflow covers several skbs and some of them have not
reached yet the received, either the worker or recvmsg()
can find a subflow with the data_avail flag set - since
the current mapping is valid and in sequence - but no
skbs in the receive queue - since the other entity just
processed them.

The above will lead to an unbounded loop in __mptcp_move_skbs()
and a subsequent hang of any task trying to acquiring the msk
socket lock.

This change addresses the issue stopping the __mptcp_move_skbs()
loop as soon as we detect the above race (empty receive queue
with data_avail set).

Reported-and-tested-by: syzbot+fcf8ca5817d6e92c6567@syzkaller.appspotmail.com
Fixes: ab174ad8 ("mptcp: move ooo skbs into msk out of order queue.")
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Reviewed-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

Currently we skip calling tcp_cleanup_rbuf() when packets
are moved into the OoO queue or simply dropped. In both
cases we still increment tp->copied_seq, and we should
ask the TCP stack to check for ack.

Fixes: c76c6956 ("mptcp: call tcp_cleanup_rbuf on subflows")
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Reviewed-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Currently data fin on data packet are not handled properly:
the 'rcv_data_fin_seq' field is interpreted as the last
sequence number carrying a valid data, but for data fin
packet with valid maps we currently store map_seq + map_len,
that is, the next value.

The 'write_seq' fields carries instead the value subseguent
to the last valid byte, so in mptcp_write_data_fin() we
never detect correctly the last DSS map.

Fixes: 7279da61 ("mptcp: Use MPTCP-level flag for sending DATA_FIN")
Fixes: 1a49b2c2 ("mptcp: Handle incoming 32-bit DATA_FIN values")
Reviewed-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The only usages of mptcp_pm_ops is to assign its address to the small_ops
field of the genl_family struct, which is a const pointer, and applying
ARRAY_SIZE() on it. Make it const to allow the compiler to put it in
read-only memory.
Signed-off-by: NRikard Falkeborn <rikard.falkeborn@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The MPTCP ADD_ADDR suboption with echo-flag=1 has no HMAC, the size is
smaller than the one initially sent without echo-flag=1. We then need to
use the correct size everywhere when we need this echo bit.

Before this patch, the wrong size was reserved but the correct amount of
bytes were written (and read): the remaining bytes contained garbage.

Fixes: 6a6c05a8 ("mptcp: send out ADD_ADDR with echo flag")
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/95Reported-and-tested-by: NDavide Caratti <dcaratti@redhat.com>
Acked-by: NGeliang Tang <geliangtang@gmail.com>
Signed-off-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Bulk of the genetlink users can use smaller ops, move them.
Signed-off-by: NJakub Kicinski <kuba@kernel.org>
Reviewed-by: NJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The peer may send a DATA_FIN mapping with either a 32-bit or 64-bit
sequence number. When a 32-bit sequence number is received for the
DATA_FIN, it must be expanded to 64 bits before comparing it to the
last acked sequence number. This expansion was missing.

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/93
Fixes: 3721b9b6 ("mptcp: Track received DATA_FIN sequence number and add related helpers")
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The msk->ack_seq value is sometimes read without the msk lock held, so
make proper use of READ_ONCE and WRITE_ONCE.
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Since commit cfde141e ("mptcp: move option parsing into
mptcp_incoming_options()"), the 3rd function argument is no longer used.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch implemented the retransmition of ADD_ADDR when no ADD_ADDR echo
is received. It added a timer with the announced address. When timeout
occurs, ADD_ADDR will be retransmitted.
Suggested-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Suggested-by: NPaolo Abeni <pabeni@redhat.com>
Acked-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NGeliang Tang <geliangtang@gmail.com>
Reviewed-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add a new struct mptcp_pm_add_entry to describe add_addr's entry.
Acked-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NGeliang Tang <geliangtang@gmail.com>
Reviewed-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch added a new helper named mptcp_destroy_common containing the
shared code between mptcp_destroy() and mptcp_sock_destruct().
Suggested-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NGeliang Tang <geliangtang@gmail.com>
Reviewed-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>