linux.git/net/tipc/node.c, branch v5.4.243

tipc: call tipc_lxc_xmit without holding node_read_lock

2023-01-18T10:42:06+00:00

commit 88956177db179e4eba7cd590971961857d1565b8 upstream.

When sending packets between nodes in netns, it calls tipc_lxc_xmit() for
peer node to receive the packets where tipc_sk_mcast_rcv()/tipc_sk_rcv()
might be called, and it's pretty much like in tipc_rcv().

Currently the local 'node rw lock' is held during calling tipc_lxc_xmit()
to protect the peer_net not being freed by another thread. However, when
receiving these packets, tipc_node_add_conn() might be called where the
peer 'node rw lock' is acquired. Then a dead lock warning is triggered by
lockdep detector, although it is not a real dead lock:

    WARNING: possible recursive locking detected
    --------------------------------------------
    conn_server/1086 is trying to acquire lock:
    ffff8880065cb020 (&n->lock#2){++--}-{2:2}, \
                     at: tipc_node_add_conn.cold.76+0xaa/0x211 [tipc]

    but task is already holding lock:
    ffff8880065cd020 (&n->lock#2){++--}-{2:2}, \
                     at: tipc_node_xmit+0x285/0xb30 [tipc]

    other info that might help us debug this:
     Possible unsafe locking scenario:

           CPU0
           ----
      lock(&n->lock#2);
      lock(&n->lock#2);

     *** DEADLOCK ***

     May be due to missing lock nesting notation

    4 locks held by conn_server/1086:
     #0: ffff8880036d1e40 (sk_lock-AF_TIPC){+.+.}-{0:0}, \
                          at: tipc_accept+0x9c0/0x10b0 [tipc]
     #1: ffff8880036d5f80 (sk_lock-AF_TIPC/1){+.+.}-{0:0}, \
                          at: tipc_accept+0x363/0x10b0 [tipc]
     #2: ffff8880065cd020 (&n->lock#2){++--}-{2:2}, \
                          at: tipc_node_xmit+0x285/0xb30 [tipc]
     #3: ffff888012e13370 (slock-AF_TIPC){+...}-{2:2}, \
                          at: tipc_sk_rcv+0x2da/0x1b40 [tipc]

    Call Trace:
     
     dump_stack_lvl+0x44/0x5b
     __lock_acquire.cold.77+0x1f2/0x3d7
     lock_acquire+0x1d2/0x610
     _raw_write_lock_bh+0x38/0x80
     tipc_node_add_conn.cold.76+0xaa/0x211 [tipc]
     tipc_sk_finish_conn+0x21e/0x640 [tipc]
     tipc_sk_filter_rcv+0x147b/0x3030 [tipc]
     tipc_sk_rcv+0xbb4/0x1b40 [tipc]
     tipc_lxc_xmit+0x225/0x26b [tipc]
     tipc_node_xmit.cold.82+0x4a/0x102 [tipc]
     __tipc_sendstream+0x879/0xff0 [tipc]
     tipc_accept+0x966/0x10b0 [tipc]
     do_accept+0x37d/0x590

This patch avoids this warning by not holding the 'node rw lock' before
calling tipc_lxc_xmit(). As to protect the 'peer_net', rcu_read_lock()
should be enough, as in cleanup_net() when freeing the netns, it calls
synchronize_rcu() before the free is continued.

Also since tipc_lxc_xmit() is like the RX path in tipc_rcv(), it makes
sense to call it under rcu_read_lock(). Note that the right lock order
must be:

   rcu_read_lock();
   tipc_node_read_lock(n);
   tipc_node_read_unlock(n);
   tipc_lxc_xmit();
   rcu_read_unlock();

instead of:

   tipc_node_read_lock(n);
   rcu_read_lock();
   tipc_node_read_unlock(n);
   tipc_lxc_xmit();
   rcu_read_unlock();

and we have to call tipc_node_read_lock/unlock() twice in
tipc_node_xmit().

Fixes: f73b12812a3d ("tipc: improve throughput between nodes in netns")
Reported-by: Shuang Li 
Signed-off-by: Xin Long 
Link: https://lore.kernel.org/r/5bdd1f8fee9db695cfff4528a48c9b9d0523fb00.1670110641.git.lucien.xin@gmail.com
Signed-off-by: Paolo Abeni 
Signed-off-by: Greg Kroah-Hartman

tipc: Add a missing case of TIPC_DIRECT_MSG type

2023-01-18T10:42:06+00:00

commit 8b1e5b0a99f04bda2d6c85ecfe5e68a356c10914 upstream.

In the commit f73b12812a3d
("tipc: improve throughput between nodes in netns"), we're missing a check
to handle TIPC_DIRECT_MSG type, it's still using old sending mechanism for
this message type. So, throughput improvement is not significant as
expected.

Besides that, when sending a large message with that type, we're also
handle wrong receiving queue, it should be enqueued in socket receiving
instead of multicast messages.

Fix this by adding the missing case for TIPC_DIRECT_MSG.

Fixes: f73b12812a3d ("tipc: improve throughput between nodes in netns")
Reported-by: Tuong Lien 
Signed-off-by: Hoang Le 
Acked-by: Jon Maloy 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

tipc: fix unexpected link reset due to discovery messages

2023-01-18T10:42:04+00:00

[ Upstream commit c244c092f1ed2acfb5af3d3da81e22367d3dd733 ]

This unexpected behavior is observed:

node 1                    | node 2
------                    | ------
link is established       | link is established
reboot                    | link is reset
up                        | send discovery message
receive discovery message |
link is established       | link is established
send discovery message    |
                          | receive discovery message
                          | link is reset (unexpected)
                          | send reset message
link is reset             |

It is due to delayed re-discovery as described in function
tipc_node_check_dest(): "this link endpoint has already reset
and re-established contact with the peer, before receiving a
discovery message from that node."

However, commit 598411d70f85 has changed the condition for calling
tipc_node_link_down() which was the acceptance of new media address.

This commit fixes this by restoring the old and correct behavior.

Fixes: 598411d70f85 ("tipc: make resetting of links non-atomic")
Acked-by: Jon Maloy 
Signed-off-by: Tung Nguyen 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin

tipc: eliminate checking netns if node established

2023-01-18T10:42:04+00:00

[ Upstream commit d408bef4bfa60bac665b6e7239269570039a968b ]

Currently, we scan over all network namespaces at each received
discovery message in order to check if the sending peer might be
present in a host local namespaces.

This is unnecessary since we can assume that a peer will not change its
location during an established session.

We now improve the condition for this testing so that we don't perform
any redundant scans.

Fixes: f73b12812a3d ("tipc: improve throughput between nodes in netns")
Acked-by: Jon Maloy 
Signed-off-by: Hoang Le 
Signed-off-by: David S. Miller 
Stable-dep-of: c244c092f1ed ("tipc: fix unexpected link reset due to discovery messages")
Signed-off-by: Sasha Levin

tipc: improve throughput between nodes in netns

2023-01-18T10:42:04+00:00

[ Upstream commit f73b12812a3d1d798b7517547ccdcf864844d2cd ]

Currently, TIPC transports intra-node user data messages directly
socket to socket, hence shortcutting all the lower layers of the
communication stack. This gives TIPC very good intra node performance,
both regarding throughput and latency.

We now introduce a similar mechanism for TIPC data traffic across
network namespaces located in the same kernel. On the send path, the
call chain is as always accompanied by the sending node's network name
space pointer. However, once we have reliably established that the
receiving node is represented by a namespace on the same host, we just
replace the namespace pointer with the receiving node/namespace's
ditto, and follow the regular socket receive patch though the receiving
node. This technique gives us a throughput similar to the node internal
throughput, several times larger than if we let the traffic go though
the full network stacks. As a comparison, max throughput for 64k
messages is four times larger than TCP throughput for the same type of
traffic.

To meet any security concerns, the following should be noted.

- All nodes joining a cluster are supposed to have been be certified
and authenticated by mechanisms outside TIPC. This is no different for
nodes/namespaces on the same host; they have to auto discover each
other using the attached interfaces, and establish links which are
supervised via the regular link monitoring mechanism. Hence, a kernel
local node has no other way to join a cluster than any other node, and
have to obey to policies set in the IP or device layers of the stack.

- Only when a sender has established with 100% certainty that the peer
node is located in a kernel local namespace does it choose to let user
data messages, and only those, take the crossover path to the receiving
node/namespace.

- If the receiving node/namespace is removed, its namespace pointer
is invalidated at all peer nodes, and their neighbor link monitoring
will eventually note that this node is gone.

- To ensure the "100% certainty" criteria, and prevent any possible
spoofing, received discovery messages must contain a proof that the
sender knows a common secret. We use the hash mix of the sending
node/namespace for this purpose, since it can be accessed directly by
all other namespaces in the kernel. Upon reception of a discovery
message, the receiver checks this proof against all the local
namespaces'hash_mix:es. If it finds a match, that, along with a
matching node id and cluster id, this is deemed sufficient proof that
the peer node in question is in a local namespace, and a wormhole can
be opened.

- We should also consider that TIPC is intended to be a cluster local
IPC mechanism (just like e.g. UNIX sockets) rather than a network
protocol, and hence we think it can justified to allow it to shortcut the
lower protocol layers.

Regarding traceability, we should notice that since commit 6c9081a3915d
("tipc: add loopback device tracking") it is possible to follow the node
internal packet flow by just activating tcpdump on the loopback
interface. This will be true even for this mechanism; by activating
tcpdump on the involved nodes' loopback interfaces their inter-name
space messaging can easily be tracked.

v2:
- update 'net' pointer when node left/rejoined
v3:
- grab read/write lock when using node ref obj
v4:
- clone traffics between netns to loopback

Suggested-by: Jon Maloy 
Acked-by: Jon Maloy 
Signed-off-by: Hoang Le 
Signed-off-by: David S. Miller 
Stable-dep-of: c244c092f1ed ("tipc: fix unexpected link reset due to discovery messages")
Signed-off-by: Sasha Levin

tipc: clean up skb list lock handling on send path

2019-08-18T21:01:07+00:00

The policy for handling the skb list locks on the send and receive paths
is simple.

- On the send path we never need to grab the lock on the 'xmitq' list
  when the destination is an exernal node.

- On the receive path we always need to grab the lock on the 'inputq'
  list, irrespective of source node.

However, when transmitting node local messages those will eventually
end up on the receive path of a local socket, meaning that the argument
'xmitq' in tipc_node_xmit() will become the 'ínputq' argument in  the
function tipc_sk_rcv(). This has been handled by always initializing
the spinlock of the 'xmitq' list at message creation, just in case it
may end up on the receive path later, and despite knowing that the lock
in most cases never will be used.

This approach is inaccurate and confusing, and has also concealed the
fact that the stated 'no lock grabbing' policy for the send path is
violated in some cases.

We now clean up this by never initializing the lock at message creation,
instead doing this at the moment we find that the message actually will
enter the receive path. At the same time we fix the four locations
where we incorrectly access the spinlock on the send/error path.

This patch also reverts commit d12cffe9329f ("tipc: ensure head->lock
is initialised") which has now become redundant.

CC: Eric Dumazet 
Reported-by: Chris Packham 
Acked-by: Ying Xue 
Signed-off-by: Jon Maloy 
Reviewed-by: Xin Long 
Signed-off-by: David S. Miller

tipc: add loopback device tracking

2019-08-09T05:11:39+00:00

Since node internal messages are passed directly to the socket, it is not
possible to observe those messages via tcpdump or wireshark.

We now remedy this by making it possible to clone such messages and send
the clones to the loopback interface.  The clones are dropped at reception
and have no functional role except making the traffic visible.

The feature is enabled if network taps are active for the loopback device.
pcap filtering restrictions require the messages to be presented to the
receiving side of the loopback device.

v3 - Function dev_nit_active used to check for network taps.
   - Procedure netif_rx_ni used to send cloned messages to loopback device.

Signed-off-by: John Rutherford 
Acked-by: Jon Maloy 
Acked-by: Ying Xue 
Signed-off-by: David S. Miller

tipc: optimize link synching mechanism

2019-07-25T22:55:47+00:00

This commit along with the next one are to resolve the issues with the
link changeover mechanism. See that commit for details.

Basically, for the link synching, from now on, we will send only one
single ("dummy") SYNCH message to peer. The SYNCH message does not
contain any data, just a header conveying the synch point to the peer.

A new node capability flag ("TIPC_TUNNEL_ENHANCED") is introduced for
backward compatible!

Acked-by: Ying Xue 
Acked-by: Jon Maloy 
Suggested-by: Jon Maloy 
Signed-off-by: Tuong Lien 
Signed-off-by: David S. Miller

tipc: initialize 'validated' field of received packets

2019-07-17T22:24:38+00:00

The tipc_msg_validate() function leaves a boolean flag 'validated' in
the validated buffer's control block, to avoid performing this action
more than once. However, at reception of new packets, the position of
this field may already have been set by lower layer protocols, so
that the packet is erroneously perceived as already validated by TIPC.

We fix this by initializing the said field to 'false' before performing
the initial validation.

Signed-off-by: Jon Maloy 
Signed-off-by: David S. Miller

tipc: rename function msg_get_wrapped() to msg_inner_hdr()

2019-06-25T20:42:54+00:00

We rename the inline function msg_get_wrapped() to the more
comprehensible msg_inner_hdr().

Signed-off-by: Jon Maloy 
Signed-off-by: David S. Miller