After commit d38afeec ("tcp/udp: Call inet6_destroy_sock()
in IPv6 sk->sk_destruct()."), we call inet6_destroy_sock() in
sk->sk_destruct() by setting inet6_sock_destruct() to it to make
sure we do not leak inet6-specific resources.

Now we can remove unnecessary inet6_destroy_sock() calls in
sk->sk_prot->destroy().

DCCP and SCTP have their own sk->sk_destruct() function, so we
change them separately in the following patches.
Signed-off-by: NKuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The MPTCP data path is quite complex and hard to understend even
without some foggy comments referring to modified code and/or
completely misleading from the beginning.

Update a few of them to more accurately describing the current
status.
Reviewed-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Daire reported a user-space application hang-up when the
peer is forcibly closed before the data transfer completion.

The relevant application expects the peer to either
do an application-level clean shutdown or a transport-level
connection reset.

We can accommodate a such user by extending the fastclose
usage: at fd close time, if the msk socket has some unread
data, and at FIN_WAIT timeout.

Note that at MPTCP close time we must ensure that the TCP
subflows will reset: set the linger socket option to a suitable
value.
Reviewed-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Reviewed-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When an mptcp socket is closed due to an incoming FASTCLOSE
option, so specific sk_err is set and later syscall will
fail usually with EPIPE.

Align the current fastclose error handling with TCP reset,
properly setting the socket error according to the current
msk state and propagating such error.

Additionally sendmsg() is currently not handling properly
the sk_err, always returning EPIPE.
Reviewed-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Reviewed-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The mptcp socket and its subflow sockets in accept queue can't be
released after the process exit.

While the release of a mptcp socket in listening state, the
corresponding tcp socket will be released too. Meanwhile, the tcp
socket in the unaccept queue will be released too. However, only init
subflow is in the unaccept queue, and the joined subflow is not in the
unaccept queue, which makes the joined subflow won't be released, and
therefore the corresponding unaccepted mptcp socket will not be released
to.

This can be reproduced easily with following steps:

1. create 2 namespace and veth:
   $ ip netns add mptcp-client
   $ ip netns add mptcp-server
   $ sysctl -w net.ipv4.conf.all.rp_filter=0
   $ ip netns exec mptcp-client sysctl -w net.mptcp.enabled=1
   $ ip netns exec mptcp-server sysctl -w net.mptcp.enabled=1
   $ ip link add red-client netns mptcp-client type veth peer red-server \
     netns mptcp-server
   $ ip -n mptcp-server address add 10.0.0.1/24 dev red-server
   $ ip -n mptcp-server address add 192.168.0.1/24 dev red-server
   $ ip -n mptcp-client address add 10.0.0.2/24 dev red-client
   $ ip -n mptcp-client address add 192.168.0.2/24 dev red-client
   $ ip -n mptcp-server link set red-server up
   $ ip -n mptcp-client link set red-client up

2. configure the endpoint and limit for client and server:
   $ ip -n mptcp-server mptcp endpoint flush
   $ ip -n mptcp-server mptcp limits set subflow 2 add_addr_accepted 2
   $ ip -n mptcp-client mptcp endpoint flush
   $ ip -n mptcp-client mptcp limits set subflow 2 add_addr_accepted 2
   $ ip -n mptcp-client mptcp endpoint add 192.168.0.2 dev red-client id \
     1 subflow

3. listen and accept on a port, such as 9999. The nc command we used
   here is modified, which makes it use mptcp protocol by default.
   $ ip netns exec mptcp-server nc -l -k -p 9999

4. open another *two* terminal and use each of them to connect to the
   server with the following command:
   $ ip netns exec mptcp-client nc 10.0.0.1 9999
   Input something after connect to trigger the connection of the second
   subflow. So that there are two established mptcp connections, with the
   second one still unaccepted.

5. exit all the nc command, and check the tcp socket in server namespace.
   And you will find that there is one tcp socket in CLOSE_WAIT state
   and can't release forever.

Fix this by closing all of the unaccepted mptcp socket in
mptcp_subflow_queue_clean() with __mptcp_close().

Now, we can ensure that all unaccepted mptcp sockets will be cleaned by
__mptcp_close() before they are released, so mptcp_sock_destruct(), which
is used to clean the unaccepted mptcp socket, is not needed anymore.

The selftests for mptcp is ran for this commit, and no new failures.

Fixes: f296234c ("mptcp: Add handling of incoming MP_JOIN requests")
Fixes: 6aeed904 ("mptcp: fix race on unaccepted mptcp sockets")
Cc: stable@vger.kernel.org
Reviewed-by: NJiang Biao <benbjiang@tencent.com>
Reviewed-by: NMengen Sun <mengensun@tencent.com>
Acked-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NMenglong Dong <imagedong@tencent.com>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

Factor out __mptcp_close() from mptcp_close(). The caller of
__mptcp_close() should hold the socket lock, and cancel mptcp work when
__mptcp_close() returns true.

This function will be used in the next commit.

Fixes: f296234c ("mptcp: Add handling of incoming MP_JOIN requests")
Fixes: 6aeed904 ("mptcp: fix race on unaccepted mptcp sockets")
Cc: stable@vger.kernel.org
Reviewed-by: NJiang Biao <benbjiang@tencent.com>
Reviewed-by: NMengen Sun <mengensun@tencent.com>
Acked-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NMenglong Dong <imagedong@tencent.com>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

If fastopen is used, poll must allow a first write that will trigger
the SYN+data

Similar to what is done in tcp_poll().
Acked-by: NPaolo Abeni <pabeni@redhat.com>
Reviewed-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: NBenjamin Hesmans <benjamin.hesmans@tessares.net>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

When TCP_FASTOPEN_CONNECT has been set on the socket before a connect,
the defer flag is set and must be handled when sendmsg is called.

This is similar to what is done in tcp_sendmsg_locked().
Acked-by: NPaolo Abeni <pabeni@redhat.com>
Reviewed-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Co-developed-by: NBenjamin Hesmans <benjamin.hesmans@tessares.net>
Signed-off-by: NBenjamin Hesmans <benjamin.hesmans@tessares.net>
Signed-off-by: NDmytro Shytyi <dmytro@shytyi.net>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

This patch adds a new bool variable 'do_check_data_fin' to replace the
original int variable 'copied' in __mptcp_push_pending(), check it to
determine whether to call __mptcp_check_send_data_fin().
Suggested-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NGeliang Tang <geliang.tang@suse.com>
Reviewed-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>

Similar to mptcp_for_each_subflow(): this is clearer now that the _safe
version is used in multiple places.
Reviewed-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>

The intel bot reported a memory accounting related splat:

[  240.473094] ------------[ cut here ]------------
[  240.478507] page_counter underflow: -4294828518 nr_pages=4294967290
[  240.485500] WARNING: CPU: 2 PID: 14986 at mm/page_counter.c:56 page_counter_cancel+0x96/0xc0
[  240.570849] CPU: 2 PID: 14986 Comm: mptcp_connect Tainted: G S                5.19.0-rc4-00739-gd24141fe #1
[  240.581637] Hardware name: HP HP Z240 SFF Workstation/802E, BIOS N51 Ver. 01.63 10/05/2017
[  240.590600] RIP: 0010:page_counter_cancel+0x96/0xc0
[  240.596179] Code: 00 00 00 45 31 c0 48 89 ef 5d 4c 89 c6 41 5c e9 40 fd ff ff 4c 89 e2 48 c7 c7 20 73 39 84 c6 05 d5 b1 52 04 01 e8 e7 95 f3
01 <0f> 0b eb a9 48 89 ef e8 1e 25 fc ff eb c3 66 66 2e 0f 1f 84 00 00
[  240.615639] RSP: 0018:ffffc9000496f7c8 EFLAGS: 00010082
[  240.621569] RAX: 0000000000000000 RBX: ffff88819c9c0120 RCX: 0000000000000000
[  240.629404] RDX: 0000000000000027 RSI: 0000000000000004 RDI: fffff5200092deeb
[  240.637239] RBP: ffff88819c9c0120 R08: 0000000000000001 R09: ffff888366527a2b
[  240.645069] R10: ffffed106cca4f45 R11: 0000000000000001 R12: 00000000fffffffa
[  240.652903] R13: ffff888366536118 R14: 00000000fffffffa R15: ffff88819c9c0000
[  240.660738] FS:  00007f3786e72540(0000) GS:ffff888366500000(0000) knlGS:0000000000000000
[  240.669529] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  240.675974] CR2: 00007f966b346000 CR3: 0000000168cea002 CR4: 00000000003706e0
[  240.683807] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  240.691641] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  240.699468] Call Trace:
[  240.702613]  <TASK>
[  240.705413]  page_counter_uncharge+0x29/0x80
[  240.710389]  drain_stock+0xd0/0x180
[  240.714585]  refill_stock+0x278/0x580
[  240.718951]  __sk_mem_reduce_allocated+0x222/0x5c0
[  240.729248]  __mptcp_update_rmem+0x235/0x2c0
[  240.734228]  __mptcp_move_skbs+0x194/0x6c0
[  240.749764]  mptcp_recvmsg+0xdfa/0x1340
[  240.763153]  inet_recvmsg+0x37f/0x500
[  240.782109]  sock_read_iter+0x24a/0x380
[  240.805353]  new_sync_read+0x420/0x540
[  240.838552]  vfs_read+0x37f/0x4c0
[  240.842582]  ksys_read+0x170/0x200
[  240.864039]  do_syscall_64+0x5c/0x80
[  240.872770]  entry_SYSCALL_64_after_hwframe+0x46/0xb0
[  240.878526] RIP: 0033:0x7f3786d9ae8e
[  240.882805] Code: c0 e9 b6 fe ff ff 50 48 8d 3d 6e 18 0a 00 e8 89 e8 01 00 66 0f 1f 84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28
[  240.902259] RSP: 002b:00007fff7be81e08 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[  240.910533] RAX: ffffffffffffffda RBX: 0000000000002000 RCX: 00007f3786d9ae8e
[  240.918368] RDX: 0000000000002000 RSI: 00007fff7be87ec0 RDI: 0000000000000005
[  240.926206] RBP: 0000000000000005 R08: 00007f3786e6a230 R09: 00007f3786e6a240
[  240.934046] R10: fffffffffffff288 R11: 0000000000000246 R12: 0000000000002000
[  240.941884] R13: 00007fff7be87ec0 R14: 00007fff7be87ec0 R15: 0000000000002000
[  240.949741]  </TASK>
[  240.952632] irq event stamp: 27367
[  240.956735] hardirqs last  enabled at (27366): [<ffffffff81ba50ea>] mem_cgroup_uncharge_skmem+0x6a/0x80
[  240.966848] hardirqs last disabled at (27367): [<ffffffff81b8fd42>] refill_stock+0x282/0x580
[  240.976017] softirqs last  enabled at (27360): [<ffffffff83a4d8ef>] mptcp_recvmsg+0xaf/0x1340
[  240.985273] softirqs last disabled at (27364): [<ffffffff83a4d30c>] __mptcp_move_skbs+0x18c/0x6c0
[  240.994872] ---[ end trace 0000000000000000 ]---

After commit d24141fe ("mptcp: drop SK_RECLAIM_* macros"),
if rmem_fwd_alloc become negative, mptcp_rmem_uncharge() can
try to reclaim a negative amount of pages, since the expression:

	reclaimable >= PAGE_SIZE

will evaluate to true for any negative value of the int
'reclaimable': 'PAGE_SIZE' is an unsigned long and
the negative integer will be promoted to a (very large)
unsigned long value.

Still after the mentioned commit, kfree_skb_partial()
in mptcp_try_coalesce() will reclaim most of just released fwd
memory, so that following charging of the skb delta size will
lead to negative fwd memory values.

At that point a racing recvmsg() can trigger the splat.

Address the issue switching the order of the memory accounting
operations. The fwd memory can still transiently reach negative
values, but that will happen in an atomic scope and no code
path could touch/use such value.
Reported-by: Nkernel test robot <oliver.sang@intel.com>
Fixes: d24141fe ("mptcp: drop SK_RECLAIM_* macros")
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Reviewed-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Link: https://lore.kernel.org/r/20220906180404.1255873-1-matthieu.baerts@tessares.netSigned-off-by: NPaolo Abeni <pabeni@redhat.com>

While reading sysctl_max_skb_frags, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its readers.

Fixes: 5f74f82e ("net:Add sysctl_max_skb_frags")
Signed-off-by: NKuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Dipanjan reported a syzbot splat at close time:

WARNING: CPU: 1 PID: 10818 at net/ipv4/af_inet.c:153
inet_sock_destruct+0x6d0/0x8e0 net/ipv4/af_inet.c:153
Modules linked in: uio_ivshmem(OE) uio(E)
CPU: 1 PID: 10818 Comm: kworker/1:16 Tainted: G           OE
5.19.0-rc6-g2eae0556bb9d #2
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.13.0-1ubuntu1.1 04/01/2014
Workqueue: events mptcp_worker
RIP: 0010:inet_sock_destruct+0x6d0/0x8e0 net/ipv4/af_inet.c:153
Code: 21 02 00 00 41 8b 9c 24 28 02 00 00 e9 07 ff ff ff e8 34 4d 91
f9 89 ee 4c 89 e7 e8 4a 47 60 ff e9 a6 fc ff ff e8 20 4d 91 f9 <0f> 0b
e9 84 fe ff ff e8 14 4d 91 f9 0f 0b e9 d4 fd ff ff e8 08 4d
RSP: 0018:ffffc9001b35fa78 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 00000000002879d0 RCX: ffff8881326f3b00
RDX: 0000000000000000 RSI: ffff8881326f3b00 RDI: 0000000000000002
RBP: ffff888179662674 R08: ffffffff87e983a0 R09: 0000000000000000
R10: 0000000000000005 R11: 00000000000004ea R12: ffff888179662400
R13: ffff888179662428 R14: 0000000000000001 R15: ffff88817e38e258
FS:  0000000000000000(0000) GS:ffff8881f5f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020007bc0 CR3: 0000000179592000 CR4: 0000000000150ee0
Call Trace:
 <TASK>
 __sk_destruct+0x4f/0x8e0 net/core/sock.c:2067
 sk_destruct+0xbd/0xe0 net/core/sock.c:2112
 __sk_free+0xef/0x3d0 net/core/sock.c:2123
 sk_free+0x78/0xa0 net/core/sock.c:2134
 sock_put include/net/sock.h:1927 [inline]
 __mptcp_close_ssk+0x50f/0x780 net/mptcp/protocol.c:2351
 __mptcp_destroy_sock+0x332/0x760 net/mptcp/protocol.c:2828
 mptcp_worker+0x5d2/0xc90 net/mptcp/protocol.c:2586
 process_one_work+0x9cc/0x1650 kernel/workqueue.c:2289
 worker_thread+0x623/0x1070 kernel/workqueue.c:2436
 kthread+0x2e9/0x3a0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302
 </TASK>

The root cause of the problem is that an mptcp-level (re)transmit can
race with mptcp_close() and the packet scheduler checks the subflow
state before acquiring the socket lock: we can try to (re)transmit on
an already closed ssk.

Fix the issue checking again the subflow socket status under the
subflow socket lock protection. Additionally add the missing check
for the fallback-to-tcp case.

Fixes: d5f49190 ("mptcp: allow picking different xmit subflows")
Reported-by: NDipanjan Das <mail.dipanjan.das@gmail.com>
Reviewed-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

If the mptcp socket creation fails due to a CGROUP_INET_SOCK_CREATE
eBPF program, the MPTCP protocol ends-up leaking all the subflows:
the related cleanup happens in __mptcp_destroy_sock() that is not
invoked in such code path.

Address the issue moving the subflow sockets cleanup in the
mptcp_destroy_common() helper, which is invoked in every msk cleanup
path.

Additionally get rid of the intermediate list_splice_init step, which
is an unneeded relic from the past.

The issue is present since before the reported root cause commit, but
any attempt to backport the fix before that hash will require a complete
rewrite.

Fixes: e16163b6 ("mptcp: refactor shutdown and close")
Reported-by: NNguyen Dinh Phi <phind.uet@gmail.com>
Reviewed-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Co-developed-by: NNguyen Dinh Phi <phind.uet@gmail.com>
Signed-off-by: NNguyen Dinh Phi <phind.uet@gmail.com>
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

While reading these sysctl variables, they can be changed concurrently.
Thus, we need to add READ_ONCE() to their readers.

  - .sysctl_rmem
  - .sysctl_rwmem
  - .sysctl_rmem_offset
  - .sysctl_wmem_offset
  - sysctl_tcp_rmem[1, 2]
  - sysctl_tcp_wmem[1, 2]
  - sysctl_decnet_rmem[1]
  - sysctl_decnet_wmem[1]
  - sysctl_tipc_rmem[1]

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: NKuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

While reading sysctl_tcp_moderate_rcvbuf, it can be changed
concurrently.  Thus, we need to add READ_ONCE() to its readers.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: NKuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The in-kernel PM has a bit of duplicate code related to ack
generation. Create a new helper factoring out the PM-specific
needs and use it in a couple of places.

As a bonus, mptcp_subflow_send_ack() is not used anymore
outside its own compilation unit and can become static.
Reviewed-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
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>

At disconnect time the MPTCP protocol traverse the subflows
list closing each of them. In some circumstances - MPJ subflow,
passive MPTCP socket, the latter operation can remove the
subflow from the list, invalidating the current iterator.

Address the issue using the safe list traversing helper
variant.
Reported-by: Nvan fantasy <g1042620637@gmail.com>
Fixes: b29fcfb5 ("mptcp: full disconnect implementation")
Tested-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Reviewed-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When setting up a subflow's flags for sending MP_PRIO MPTCP options, the
subflow socket lock was not held while reading and modifying several
struct members that are also read and modified in mptcp_write_options().

Acquire the subflow socket lock earlier and send the MP_PRIO ACK with
that lock already acquired. Add a new variant of the
mptcp_subflow_send_ack() helper to use with the subflow lock held.

Fixes: 06706542 ("mptcp: add the outgoing MP_PRIO support")
Acked-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Similar to commit 7c80b038 ("net: fix sk_wmem_schedule() and
sk_rmem_schedule() errors"), let the MPTCP receive path schedule
exactly the required amount of memory.
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

After commit 4890b686 ("net: keep sk->sk_forward_alloc as small as
possible"), the MPTCP protocol is the last SK_RECLAIM_CHUNK and
SK_RECLAIM_THRESHOLD users.

Update the MPTCP reclaim schema to match the core/TCP one and drop the
mentioned macros. This additionally clean the MPTCP code a bit.
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The memory accounting is broken in such exceptional code
path, and after commit 4890b686 ("net: keep sk->sk_forward_alloc
as small as possible") we can't find much help there.

Drop the broken code.
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When the listener socket owning the relevant request is closed,
it frees the unaccepted subflows and that causes later deletion
of the paired MPTCP sockets.

The mptcp socket's worker can run in the time interval between such delete
operations. When that happens, any access to msk->first will cause an UaF
access, as the subflow cleanup did not cleared such field in the mptcp
socket.

Address the issue explicitly traversing the listener socket accept
queue at close time and performing the needed cleanup on the pending
msk.

Note that the locking is a bit tricky, as we need to acquire the msk
socket lock, while still owning the subflow socket one.

Fixes: 86e39e04 ("mptcp: keep track of local endpoint still available for each msk")
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>

If the MPTCP socket shutdown happens before a fallback
to TCP, and all the pending data have been already spooled,
we never close the TCP connection.

Address the issue explicitly checking for critical condition
at fallback time.

Fixes: 1e39e5a3 ("mptcp: infinite mapping sending")
Fixes: 0348c690 ("mptcp: add the fallback check")
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>

mptcp_mp_fail_no_response shouldn't be invoked on each worker run, it
should be invoked only when MP_FAIL response timeout occurs.

This patch refactors the MP_FAIL response logic.

It leverages the fact that only the MPC/first subflow can gracefully
fail to avoid unneeded subflows traversal: the failing subflow can
be only msk->first.

A new 'fail_tout' field is added to the subflow context to record the
MP_FAIL response timeout and use such field to reliably share the
timeout timer between the MP_FAIL event and the MPTCP socket close
timeout.

Finally, a new ack is generated to send out MP_FAIL notification as soon
as we hit the relevant condition, instead of waiting a possibly unbound
time for the next data packet.

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/281
Fixes: d9fb7970 ("mptcp: Do not traverse the subflow connection list without lock")
Co-developed-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NGeliang Tang <geliang.tang@suse.com>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

Currently, tcp_memory_allocated can hit tcp_mem[] limits quite fast.

Each TCP socket can forward allocate up to 2 MB of memory, even after
flow became less active.

10,000 sockets can have reserved 20 GB of memory,
and we have no shrinker in place to reclaim that.

Instead of trying to reclaim the extra allocations in some places,
just keep sk->sk_forward_alloc values as small as possible.

This should not impact performance too much now we have per-cpu
reserves: Changes to tcp_memory_allocated should not be too frequent.

For sockets not using SO_RESERVE_MEM:
 - idle sockets (no packets in tx/rx queues) have zero forward alloc.
 - non idle sockets have a forward alloc smaller than one page.

Note:

 - Removal of SK_RECLAIM_CHUNK and SK_RECLAIM_THRESHOLD
   is left to MPTCP maintainers as a follow up.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Reviewed-by: NShakeel Butt <shakeelb@google.com>
Acked-by: NSoheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

Each protocol having a ->memory_allocated pointer gets a corresponding
per-cpu reserve, that following patches will use.

Instead of having reserved bytes per socket,
we want to have per-cpu reserves.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Reviewed-by: NShakeel Butt <shakeelb@google.com>
Acked-by: NSoheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

Due to memcg interface, SK_MEM_QUANTUM is effectively PAGE_SIZE.

This might change in the future, but it seems better to avoid the
confusion.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Reviewed-by: NShakeel Butt <shakeelb@google.com>
Acked-by: NSoheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

The MPTCP socket's conn_list (list of subflows) requires the socket lock
to access. The MP_FAIL timeout code added such an access, where it would
check the list of subflows both in timer context and (later) in workqueue
context where the socket lock is held.

Rather than check the list twice, remove the check in the timeout
handler and only depend on the check in the workqueue. Also remove the
MPTCP_FAIL_NO_RESPONSE flag, since mptcp_mp_fail_no_response() has
insignificant overhead and can be checked on each worker run.

Fixes: 49fa1919 ("mptcp: reset subflow when MP_FAIL doesn't respond")
Reported-by: NPaolo Abeni <pabeni@redhat.com>
Reviewed-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>

This reverts commit 4293248c.

Additional locks are not needed, all the touched sections
are already under mptcp socket lock protection.

Fixes: 4293248c ("mptcp: add data lock for sk timers")
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>

As per RFC, the offered MPTCP-level window should never shrink.
While we currently track the right edge, we don't enforce the
above constraint on the wire.
Additionally, concurrent xmit on different subflows can end-up in
erroneous right edge update.
Address the above explicitly updating the announced window and
protecting the update with an additional atomic operation (sic)
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>

Bump a counter for counter when snd_wnd is shared among subflow,
for observability's sake.
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>

As per RFC, mptcp subflows use a "shared" snd_wnd: the effective
window is the maximum among the current values received on all
subflows. Without such feature a data transfer using multiple
subflows could block.

Window sharing is currently implemented in the RX side:
__tcp_select_window uses the mptcp-level receive buffer to compute
the announced window.

That is not enough: the TCP stack will stick to the window size
received on the given subflow; we need to propagate the msk window
value on each subflow at xmit time.

Change the packet scheduler to ignore the subflow level window
and use instead the msk level one
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>

Switch net callers to the new API not requiring
the NAPI_POLL_WEIGHT argument.
Acked-by: NFlorian Fainelli <f.fainelli@gmail.com>
Reviewed-by: NAlex Elder <elder@linaro.org>
Acked-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Acked-by: NAlexandra Winter <wintera@linux.ibm.com>
Link: https://lore.kernel.org/r/20220504163725.550782-1-kuba@kernel.orgSigned-off-by: NJakub Kicinski <kuba@kernel.org>

This change adds an internal function to store/retrieve local
addrs announced by userspace PM implementations to/from its kernel
context. The function addresses the requirements of three scenarios:
1) ADD_ADDR announcements (which require that a local id be
provided), 2) retrieving the local id associated with an address,
and also where one may need to be assigned, and 3) reissuance of
ADD_ADDRs when there's a successful match of addr/id.

The list of all stored local addr entries is held under the
MPTCP sock structure. Memory for these entries is allocated from
the sock option buffer, so the list of addrs is bounded by optmem_max.
The list if not released via REMOVE_ADDR signals is ultimately
freed when the sock is destructed.
Acked-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NKishen Maloor <kishen.maloor@intel.com>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This change updates internal logic to permit subflows to be
established from either the client or server ends of MPTCP
connections. This symmetry and added flexibility may be
harnessed by PM implementations running on either end in
creating new subflows.

The essence of this change lies in not relying on the
"server_side" flag (which continues to be available if needed).
Acked-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NKishen Maloor <kishen.maloor@intel.com>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

This patch adds a new msk->flags bit MPTCP_FAIL_NO_RESPONSE, then reuses
sk_timer to trigger a check if we have not received a response from the
peer after sending MP_FAIL. If the peer doesn't respond properly, reset
the subflow.
Signed-off-by: NGeliang Tang <geliang.tang@suse.com>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

mptcp_data_lock() needs to be held when manipulating the msk
retransmit_timer or the sk sk_timer. This patch adds the data
lock for the both timers.
Signed-off-by: NGeliang Tang <geliang.tang@suse.com>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Use the helper mptcp_stop_timer() instead of using sk_stop_timer() to
stop icsk_retransmit_timer directly.
Signed-off-by: NGeliang Tang <geliang.tang@suse.com>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch adds a new mib named MPTCP_MIB_INFINITEMAPTX, increase it
when a infinite mapping has been sent out.
Signed-off-by: NGeliang Tang <geliang.tang@suse.com>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>