rxrpc: Do zerocopy using MSG_SPLICE_PAGES and page frags

Switch from keeping the transmission buffers in the rxrpc_txbuf struct and
allocated from the slab, to allocating them using page fragment allocators
(which uses raw pages), thereby allowing them to be passed to
MSG_SPLICE_PAGES and avoid copying into the UDP buffers.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: "David S. Miller" <davem@davemloft.net>
cc: Eric Dumazet <edumazet@google.com>
cc: Jakub Kicinski <kuba@kernel.org>
cc: Paolo Abeni <pabeni@redhat.com>
cc: linux-afs@lists.infradead.org
cc: netdev@vger.kernel.org

rxrpc: Fix two connection reaping bugs

Fix two connection reaping bugs:

(1) rxrpc_connection_expiry is in units of seconds, so
rxrpc_disconnect_call() needs to multiply it by HZ when adding it to
jiffies.

(2) rxrpc_client_conn_reap_timeout() should set RXRPC_CLIENT_REAP_TIMER if
local->kill_all_client_conns is clear, not if it is set (in which case
we don't need the timer). Without this, old client connections don't
get cleaned up until the local endpoint is cleaned up.

Fixes: 5040011d073d ("rxrpc: Make the local endpoint hold a ref on a connected call")
Fixes: 0d6bf319bc5a ("rxrpc: Move the client conn cache management to the I/O thread")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Link: https://lore.kernel.org/r/783911.1698364174@warthog.procyon.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

rxrpc: Move client call connection to the I/O thread

Move the connection setup of client calls to the I/O thread so that a whole
load of locking and barrierage can be eliminated. This necessitates the
app thread waiting for connection to complete before it can begin
encrypting data.

This also completes the fix for a race that exists between call connection
and call disconnection whereby the data transmission code adds the call to
the peer error distribution list after the call has been disconnected (say
by the rxrpc socket getting closed).

The fix is to complete the process of moving call connection, data
transmission and call disconnection into the I/O thread and thus forcibly
serialising them.

Note that the issue may predate the overhaul to an I/O thread model that
were included in the merge window for v6.2, but the timing is very much
changed by the change given below.

Fixes: cf37b5987508 ("rxrpc: Move DATA transmission into call processor work item")
Reported-by: syzbot+c22650d2844392afdcfd@syzkaller.appspotmail.com
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org

rxrpc: Move the client conn cache management to the I/O thread

Move the management of the client connection cache to the I/O thread rather
than managing it from the namespace as an aggregate across all the local
endpoints within the namespace.

This will allow a load of locking to be got rid of in a future patch as
only the I/O thread will be looking at the this.

The downside is that the total number of cached connections on the system
can get higher because the limit is now per-local rather than per-netns.
We can, however, keep the number of client conns in use across the entire
netfs and use that to reduce the expiration time of idle connection.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org

rxrpc: Set up a connection bundle from a call, not rxrpc_conn_parameters

Use the information now stored in struct rxrpc_call to configure the
connection bundle and thence the connection, rather than using the
rxrpc_conn_parameters struct.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org

rxrpc: Make the set of connection IDs per local endpoint

Make the set of connection IDs per local endpoint so that endpoints don't
cause each other's connections to get dismissed.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org

rxrpc: Implement a mechanism to send an event notification to a connection

Provide a means by which an event notification can be sent to a connection
through such that the I/O thread can pick it up and handle it rather than
doing it in a separate workqueue.

This is then used to move the deferred final ACK of a call into the I/O
thread rather than a separate work queue as part of the drive to do all
transmission from the I/O thread.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org

rxrpc: Make the local endpoint hold a ref on a connected call

Make the local endpoint and it's I/O thread hold a reference on a connected
call until that call is disconnected. Without this, we're reliant on
either the AF_RXRPC socket to hold a ref (which is dropped when the call is
released) or a queued work item to hold a ref (the work item is being
replaced with the I/O thread).

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org

rxrpc: Make the I/O thread take over the call and local processor work

Move the functions from the call->processor and local->processor work items
into the domain of the I/O thread.

The call event processor, now called from the I/O thread, then takes over
the job of cranking the call state machine, processing incoming packets and
transmitting DATA, ACK and ABORT packets. In a future patch,
rxrpc_send_ACK() will transmit the ACK on the spot rather than queuing it
for later transmission.

The call event processor becomes purely received-skb driven. It only
transmits things in response to events. We use "pokes" to queue a dummy
skb to make it do things like start/resume transmitting data. Timer expiry
also results in pokes.

The connection event processor, becomes similar, though crypto events, such
as dealing with CHALLENGE and RESPONSE packets is offloaded to a work item
to avoid doing crypto in the I/O thread.

The local event processor is removed and VERSION response packets are
generated directly from the packet parser. Similarly, ABORTs generated in
response to protocol errors will be transmitted immediately rather than
being pushed onto a queue for later transmission.

Changes:
========
ver #2)
- Fix a couple of introduced lock context imbalances.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org

rxrpc: Extract the peer address from an incoming packet earlier

Extract the peer address from an incoming packet earlier, at the beginning
of rxrpc_input_packet() and thence pass a pointer to it to various
functions that use it as part of the lookup rather than doing it on several
separate paths.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org

rxrpc: Remove RCU from peer->error_targets list

Remove the RCU requirements from the peer's list of error targets so that
the error distributor can call sleeping functions.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org

rxrpc: Don't hold a ref for connection workqueue

Currently, rxrpc gives the connection's work item a ref on the connection
when it queues it - and this is called from the timer expiration function.
The problem comes when queue_work() fails (ie. the work item is already
queued): the timer routine must put the ref - but this may cause the
cleanup code to run.

This has the unfortunate effect that the cleanup code may then be run in
softirq context - which means that any spinlocks it might need to touch
have to be guarded to disable softirqs (ie. they need a "_bh" suffix).

(1) Don't give a ref to the work item.

(2) Simplify handling of service connections by adding a separate active
count so that the refcount isn't also used for this.

(3) Connection destruction for both client and service connections can
then be cleaned up by putting rxrpc_put_connection() out of line and
making a tidy progression through the destruction code (offloaded to a
workqueue if put from softirq or processor function context). The RCU
part of the cleanup then only deals with the freeing at the end.

(4) Make rxrpc_queue_conn() return immediately if it sees the active count
is -1 rather then queuing the connection.

(5) Make sure that the cleanup routine waits for the work item to
complete.

(6) Stash the rxrpc_net pointer in the conn struct so that the rcu free
routine can use it, even if the local endpoint has been freed.

Unfortunately, neither the timer nor the work item can simply get around
the problem by just using refcount_inc_not_zero() as the waits would still
have to be done, and there would still be the possibility of having to put
the ref in the expiration function.

Note the connection work item is mostly going to go away with the main
event work being transferred to the I/O thread, so the wait in (6) will
become obsolete.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org

rxrpc: Trace rxrpc_bundle refcount

Add a tracepoint for the rxrpc_bundle refcounting.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org

rxrpc: trace: Don't use __builtin_return_address for rxrpc_conn tracing

In rxrpc tracing, use enums to generate lists of points of interest rather
than __builtin_return_address() for the rxrpc_conn tracepoint

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org

rxrpc: trace: Don't use __builtin_return_address for rxrpc_peer tracing

In rxrpc tracing, use enums to generate lists of points of interest rather
than __builtin_return_address() for the rxrpc_peer tracepoint

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org

rxrpc: trace: Don't use __builtin_return_address for rxrpc_local tracing

In rxrpc tracing, use enums to generate lists of points of interest rather
than __builtin_return_address() for the rxrpc_local tracepoint

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org

rxrpc: Drop rxrpc_conn_parameters from rxrpc_connection and rxrpc_bundle

Remove the rxrpc_conn_parameters struct from the rxrpc_connection and
rxrpc_bundle structs and emplace the members directly. These are going to
get filled in from the rxrpc_call struct in future.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org

rxrpc: Remove the [_k]net() debugging macros

Remove the _net() and knet() debugging macros in favour of tracepoints.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org

rxrpc: Fix congestion management

rxrpc has a problem in its congestion management in that it saves the
congestion window size (cwnd) from one call to another, but if this is 0 at
the time is saved, then the next call may not actually manage to ever
transmit anything.

To this end:

(1) Don't save cwnd between calls, but rather reset back down to the
initial cwnd and re-enter slow-start if data transmission is idle for
more than an RTT.

(2) Preserve ssthresh instead, as that is a handy estimate of pipe
capacity. Knowing roughly when to stop slow start and enter
congestion avoidance can reduce the tendency to overshoot and drop
larger amounts of packets when probing.

In future, cwind growth also needs to be constrained when the window isn't
being filled due to being application limited.

Reported-by: Simon Wilkinson <sxw@auristor.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org

rxrpc: Get rid of the Rx ring

Get rid of the Rx ring and replace it with a pair of queues instead. One
queue gets the packets that are in-sequence and are ready for processing by
recvmsg(); the other queue gets the out-of-sequence packets for addition to
the first queue as the holes get filled.

The annotation ring is removed and replaced with a SACK table. The SACK
table has the bits set that correspond exactly to the sequence number of
the packet being acked. The SACK ring is copied when an ACK packet is
being assembled and rotated so that the first ACK is in byte 0.

Flow control handling is altered so that packets that are moved to the
in-sequence queue are hard-ACK'd even before they're consumed - and then
the Rx window size in the ACK packet (rsize) is shrunk down to compensate
(even going to 0 if the window is full).

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org

rxrpc, afs: Fix selection of abort codes

The RX_USER_ABORT code should really only be used to indicate that the user
of the rxrpc service (ie. userspace) implicitly caused a call to be aborted
- for instance if the AF_RXRPC socket is closed whilst the call was in
progress. (The user may also explicitly abort a call and specify the abort
code to use).

Change some of the points of generation to use other abort codes instead:

(1) Abort the call with RXGEN_SS_UNMARSHAL or RXGEN_CC_UNMARSHAL if we see
ENOMEM and EFAULT during received data delivery and abort with
RX_CALL_DEAD in the default case.

(2) Abort with RXGEN_SS_MARSHAL if we get ENOMEM whilst trying to send a
reply.

(3) Abort with RX_CALL_DEAD if we stop hearing from the peer if we had
heard from the peer and abort with RX_CALL_TIMEOUT if we hadn't.

(4) Abort with RX_CALL_DEAD if we try to disconnect a call that's not
completed successfully or been aborted.

Reported-by: Jeffrey Altman <jaltman@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Signed-off-by: David S. Miller <davem@davemloft.net>

rxrpc: Use refcount_t rather than atomic_t

Move to using refcount_t rather than atomic_t for refcounts in rxrpc.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Signed-off-by: David S. Miller <davem@davemloft.net>

rxrpc: Ask the security class how much space to allow in a packet

Ask the security class how much header and trailer space to allow for when
allocating a packet, given how much data is remaining.

This will allow the rxgk security class to stick both a trailer in as well
as a header as appropriate in the future.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Don't retain the server key in the connection

Don't retain a pointer to the server key in the connection, but rather get
it on demand when the server has to deal with a response packet.

This is necessary to implement RxGK (GSSAPI-mediated transport class),
where we can't know which key we'll need until we've challenged the client
and got back the response.

This also means that we don't need to do a key search in the accept path in
softirq mode.

Also, whilst we're at it, allow the security class to ask for a kvno and
encoding-type variant of a server key as RxGK needs different keys for
different encoding types. Keys of this type have an extra bit in the
description:

"<service-id>:<security-index>:<kvno>:<enctype>"

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Rewrite the client connection manager

Rewrite the rxrpc client connection manager so that it can support multiple
connections for a given security key to a peer. The following changes are
made:

(1) For each open socket, the code currently maintains an rbtree with the
connections placed into it, keyed by communications parameters. This
is tricky to maintain as connections can be culled from the tree or
replaced within it. Connections can require replacement for a number
of reasons, e.g. their IDs span too great a range for the IDR data
type to represent efficiently, the call ID numbers on that conn would
overflow or the conn got aborted.

This is changed so that there's now a connection bundle object placed
in the tree, keyed on the same parameters. The bundle, however, does
not need to be replaced.

(2) An rxrpc_bundle object can now manage the available channels for a set
of parallel connections. The lock that manages this is moved there
from the rxrpc_connection struct (channel_lock).

(3) There'a a dummy bundle for all incoming connections to share so that
they have a channel_lock too. It might be better to give each
incoming connection its own bundle. This bundle is not needed to
manage which channels incoming calls are made on because that's the
solely at whim of the client.

(4) The restrictions on how many client connections are around are
removed. Instead, a previous patch limits the number of client calls
that can be allocated. Ordinarily, client connections are reaped
after 2 minutes on the idle queue, but when more than a certain number
of connections are in existence, the reaper starts reaping them after
2s of idleness instead to get the numbers back down.

It could also be made such that new call allocations are forced to
wait until the number of outstanding connections subsides.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Fix race between recvmsg and sendmsg on immediate call failure

There's a race between rxrpc_sendmsg setting up a call, but then failing to
send anything on it due to an error, and recvmsg() seeing the call
completion occur and trying to return the state to the user.

An assertion fails in rxrpc_recvmsg() because the call has already been
released from the socket and is about to be released again as recvmsg deals
with it. (The recvmsg_q queue on the socket holds a ref, so there's no
problem with use-after-free.)

We also have to be careful not to end up reporting an error twice, in such
a way that both returns indicate to userspace that the user ID supplied
with the call is no longer in use - which could cause the client to
malfunction if it recycles the user ID fast enough.

Fix this by the following means:

(1) When sendmsg() creates a call after the point that the call has been
successfully added to the socket, don't return any errors through
sendmsg(), but rather complete the call and let recvmsg() retrieve
them. Make sendmsg() return 0 at this point. Further calls to
sendmsg() for that call will fail with ESHUTDOWN.

Note that at this point, we haven't send any packets yet, so the
server doesn't yet know about the call.

(2) If sendmsg() returns an error when it was expected to create a new
call, it means that the user ID wasn't used.

(3) Mark the call disconnected before marking it completed to prevent an
oops in rxrpc_release_call().

(4) recvmsg() will then retrieve the error and set MSG_EOR to indicate
that the user ID is no longer known by the kernel.

An oops like the following is produced:

kernel BUG at net/rxrpc/recvmsg.c:605!
...
RIP: 0010:rxrpc_recvmsg+0x256/0x5ae
...
Call Trace:
? __init_waitqueue_head+0x2f/0x2f
____sys_recvmsg+0x8a/0x148
? import_iovec+0x69/0x9c
? copy_msghdr_from_user+0x5c/0x86
___sys_recvmsg+0x72/0xaa
? __fget_files+0x22/0x57
? __fget_light+0x46/0x51
? fdget+0x9/0x1b
do_recvmmsg+0x15e/0x232
? _raw_spin_unlock+0xa/0xb
? vtime_delta+0xf/0x25
__x64_sys_recvmmsg+0x2c/0x2f
do_syscall_64+0x4c/0x78
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Fixes: 357f5ef64628 ("rxrpc: Call rxrpc_release_call() on error in rxrpc_new_client_call()")
Reported-by: syzbot+b54969381df354936d96@syzkaller.appspotmail.com
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

rxrpc: Fix service call disconnection

The recent patch that substituted a flag on an rxrpc_call for the
connection pointer being NULL as an indication that a call was disconnected
puts the set_bit in the wrong place for service calls. This is only a
problem if a call is implicitly terminated by a new call coming in on the
same connection channel instead of a terminating ACK packet.

In such a case, rxrpc_input_implicit_end_call() calls
__rxrpc_disconnect_call(), which is now (incorrectly) setting the
disconnection bit, meaning that when rxrpc_release_call() is later called,
it doesn't call rxrpc_disconnect_call() and so the call isn't removed from
the peer's error distribution list and the list gets corrupted.

KASAN finds the issue as an access after release on a call, but the
position at which it occurs is confusing as it appears to be related to a
different call (the call site is where the latter call is being removed
from the error distribution list and either the next or pprev pointer
points to a previously released call).

Fix this by moving the setting of the flag from __rxrpc_disconnect_call()
to rxrpc_disconnect_call() in the same place that the connection pointer
was being cleared.

Fixes: 5273a191dca6 ("rxrpc: Fix NULL pointer deref due to call->conn being cleared on disconnect")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

rxrpc: Fix NULL pointer deref due to call->conn being cleared on disconnect

When a call is disconnected, the connection pointer from the call is
cleared to make sure it isn't used again and to prevent further attempted
transmission for the call. Unfortunately, there might be a daemon trying
to use it at the same time to transmit a packet.

Fix this by keeping call->conn set, but setting a flag on the call to
indicate disconnection instead.

Remove also the bits in the transmission functions where the conn pointer is
checked and a ref taken under spinlock as this is now redundant.

Fixes: 8d94aa381dab ("rxrpc: Calls shouldn't hold socket refs")
Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Fix trace-after-put looking at the put connection record

rxrpc_put_*conn() calls trace_rxrpc_conn() after they have done the
decrement of the refcount - which looks at the debug_id in the connection
record. But unless the refcount was reduced to zero, we no longer have the
right to look in the record and, indeed, it may be deleted by some other
thread.

Fix this by getting the debug_id out before decrementing the refcount and
then passing that into the tracepoint.

Fixes: 363deeab6d0f ("rxrpc: Add connection tracepoint and client conn state tracepoint")
Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Fix lack of conn cleanup when local endpoint is cleaned up [ver #2]

When a local endpoint is ceases to be in use, such as when the kafs module
is unloaded, the kernel will emit an assertion failure if there are any
outstanding client connections:

rxrpc: Assertion failed
------------[ cut here ]------------
kernel BUG at net/rxrpc/local_object.c:433!

and even beyond that, will evince other oopses if there are service
connections still present.

Fix this by:

(1) Removing the triggering of connection reaping when an rxrpc socket is
released. These don't actually clean up the connections anyway - and
further, the local endpoint may still be in use through another
socket.

(2) Mark the local endpoint as dead when we start the process of tearing
it down.

(3) When destroying a local endpoint, strip all of its client connections
from the idle list and discard the ref on each that the list was
holding.

(4) When destroying a local endpoint, call the service connection reaper
directly (rather than through a workqueue) to immediately kill off all
outstanding service connections.

(5) Make the service connection reaper reap connections for which the
local endpoint is marked dead.

Only after destroying the connections can we close the socket lest we get
an oops in a workqueue that's looking at a connection or a peer.

Fixes: 3d18cbb7fd0c ("rxrpc: Fix conn expiry timers")
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

rxrpc: Drop the local endpoint arg from rxrpc_extract_addr_from_skb()

rxrpc_extract_addr_from_skb() doesn't use the argument that points to the
local endpoint, so remove the argument.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Use IPv4 addresses throught the IPv6

AF_RXRPC opens an IPv6 socket through which to send and receive network
packets, both IPv6 and IPv4. It currently turns AF_INET addresses into
AF_INET-as-AF_INET6 addresses based on an assumption that this was
necessary; on further inspection of the code, however, it turns out that
the IPv6 code just farms packets aimed at AF_INET addresses out to the IPv4
code.

Fix AF_RXRPC to use AF_INET addresses directly when given them.

Fixes: 7b674e390e51 ("rxrpc: Fix IPv6 support")
Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Fix error distribution

Fix error distribution by immediately delivering the errors to all the
affected calls rather than deferring them to a worker thread. The problem
with the latter is that retries and things can happen in the meantime when we
want to stop that sooner.

To this end:

(1) Stop the error distributor from removing calls from the error_targets
list so that peer->lock isn't needed to synchronise against other adds
and removals.

(2) Require the peer's error_targets list to be accessed with RCU, thereby
avoiding the need to take peer->lock over distribution.

(3) Don't attempt to affect a call's state if it is already marked complete.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Make service call handling more robust

Make the following changes to improve the robustness of the code that sets
up a new service call:

(1) Cache the rxrpc_sock struct obtained in rxrpc_data_ready() to do a
service ID check and pass that along to rxrpc_new_incoming_call().
This means that I can remove the check from rxrpc_new_incoming_call()
without the need to worry about the socket attached to the local
endpoint getting replaced - which would invalidate the check.

(2) Cache the rxrpc_peer struct, thereby allowing the peer search to be
done once. The peer is passed to rxrpc_new_incoming_call(), thereby
saving the need to repeat the search.

This also reduces the possibility of rxrpc_publish_service_conn()
BUG()'ing due to the detection of a duplicate connection, despite the
initial search done by rxrpc_find_connection_rcu() having turned up
nothing.

This BUG() shouldn't ever get hit since rxrpc_data_ready() *should* be
non-reentrant and the result of the initial search should still hold
true, but it has proven possible to hit.

I *think* this may be due to __rxrpc_lookup_peer_rcu() cutting short
the iteration over the hash table if it finds a matching peer with a
zero usage count, but I don't know for sure since it's only ever been
hit once that I know of.

Another possibility is that a bug in rxrpc_data_ready() that checked
the wrong byte in the header for the RXRPC_CLIENT_INITIATED flag
might've let through a packet that caused a spurious and invalid call
to be set up. That is addressed in another patch.

(3) Fix __rxrpc_lookup_peer_rcu() to skip peer records that have a zero
usage count rather than stopping and returning not found, just in case
there's another peer record behind it in the bucket.

(4) Don't search the peer records in rxrpc_alloc_incoming_call(), but
rather either use the peer cached in (2) or, if one wasn't found,
preemptively install a new one.

Fixes: 8496af50eb38 ("rxrpc: Use RCU to access a peer's service connection tree")
Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Fix checks as to whether we should set up a new call

There's a check in rxrpc_data_ready() that's checking the CLIENT_INITIATED
flag in the packet type field rather than in the packet flags field.

Fix this by creating a pair of helper functions to check whether the packet
is going to the client or to the server and use them generally.

Fixes: 248f219cb8bc ("rxrpc: Rewrite the data and ack handling code")
Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Remove dup code from rxrpc_find_connection_rcu()

rxrpc_find_connection_rcu() initialises variable k twice with the same
information. Remove one of the initialisations.

Signed-off-by: David Howells <dhowells@redhat.com>

atomics/treewide: Rename __atomic_add_unless() => atomic_fetch_add_unless()

While __atomic_add_unless() was originally intended as a building-block
for atomic_add_unless(), it's now used in a number of places around the
kernel. It's the only common atomic operation named __atomic*(), rather
than atomic_*(), and for consistency it would be better named
atomic_fetch_add_unless().

This lack of consistency is slightly confusing, and gets in the way of
scripting atomics. Given that, let's clean things up and promote it to
an official part of the atomics API, in the form of
atomic_fetch_add_unless().

This patch converts definitions and invocations over to the new name,
including the instrumented version, using the following script:

----
git grep -w __atomic_add_unless | while read line; do
sed -i '{s/\<__atomic_add_unless\>/atomic_fetch_add_unless/}' "${line%%:*}";
done
git grep -w __arch_atomic_add_unless | while read line; do
sed -i '{s/\<__arch_atomic_add_unless\>/arch_atomic_fetch_add_unless/}' "${line%%:*}";
done
----

Note that we do not have atomic{64,_long}_fetch_add_unless(), which will
be introduced by later patches.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Palmer Dabbelt <palmer@sifive.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/lkml/20180621121321.4761-2-mark.rutland@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

rxrpc: Fix apparent leak of rxrpc_local objects

rxrpc_local objects cannot be disposed of until all the connections that
point to them have been RCU'd as a connection object holds refcount on the
local endpoint it is communicating through. Currently, this can cause an
assertion failure to occur when a network namespace is destroyed as there's
no check that the RCU destructors for the connections have been run before
we start trying to destroy local endpoints.

The kernel reports:

rxrpc: AF_RXRPC: Leaked local 0000000036a41bc1 {5}
------------[ cut here ]------------
kernel BUG at ../net/rxrpc/local_object.c:439!

Fix this by keeping a count of the live connections and waiting for it to
go to zero at the end of rxrpc_destroy_all_connections().

Fixes: dee46364ce6f ("rxrpc: Add RCU destruction for connections and calls")
Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Fix checker warnings and errors

Fix various issues detected by checker.

Errors:

(*) rxrpc_discard_prealloc() should be using rcu_assign_pointer to set
call->socket.

Warnings:

(*) rxrpc_service_connection_reaper() should be passing NULL rather than 0 to
trace_rxrpc_conn() as the where argument.

(*) rxrpc_disconnect_client_call() should get its net pointer via the
call->conn rather than call->sock to avoid a warning about accessing
an RCU pointer without protection.

(*) Proc seq start/stop functions need annotation as they pass locks
between the functions.

False positives:

(*) Checker doesn't correctly handle of seq-retry lock context balance in
rxrpc_find_service_conn_rcu().

(*) Checker thinks execution may proceed past the BUG() in
rxrpc_publish_service_conn().

(*) Variable length array warnings from SKCIPHER_REQUEST_ON_STACK() in
rxkad.c.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Fix received abort handling

AF_RXRPC is incorrectly sending back to the server any abort it receives
for a client connection. This is due to the final-ACK offload to the
connection event processor patch. The abort code is copied into the
last-call information on the connection channel and then the event
processor is set.

Instead, the following should be done:

(1) In the case of a final-ACK for a successful call, the ACK should be
scheduled as before.

(2) In the case of a locally generated ABORT, the ABORT details should be
cached for sending in response to further packets related to that
call and no further action scheduled at call disconnect time.

(3) In the case of an ACK received from the peer, the call should be
considered dead, no ABORT should be transmitted at this time. In
response to further non-ABORT packets from the peer relating to this
call, an RX_USER_ABORT ABORT should be transmitted.

(4) In the case of a call killed due to network error, an RX_USER_ABORT
ABORT should be cached for transmission in response to further
packets, but no ABORT should be sent at this time.

Fixes: 3136ef49a14c ("rxrpc: Delay terminal ACK transmission on a client call")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

rxrpc: Clean up whitespace

Clean up some whitespace from rxrpc.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Fix conn expiry timers

Fix the rxrpc connection expiry timers so that connections for closed
AF_RXRPC sockets get deleted in a more timely fashion, freeing up the
transport UDP port much more quickly.

(1) Replace the delayed work items with work items plus timers so that
timer_reduce() can be used to shorten them and so that the timer
doesn't requeue the work item if the net namespace is dead.

(2) Don't use queue_delayed_work() as that won't alter the timeout if the
timer is already running.

(3) Don't rearm the timers if the network namespace is dead.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Fix service endpoint expiry

RxRPC service endpoints expire like they're supposed to by the following
means:

(1) Mark dead rxrpc_net structs (with ->live) rather than twiddling the
global service conn timeout, otherwise the first rxrpc_net struct to
die will cause connections on all others to expire immediately from
then on.

(2) Mark local service endpoints for which the socket has been closed
(->service_closed) so that the expiration timeout can be much
shortened for service and client connections going through that
endpoint.

(3) rxrpc_put_service_conn() needs to schedule the reaper when the usage
count reaches 1, not 0, as idle conns have a 1 count.

(4) The accumulator for the earliest time we might want to schedule for
should be initialised to jiffies + MAX_JIFFY_OFFSET, not ULONG_MAX as
the comparison functions use signed arithmetic.

(5) Simplify the expiration handling, adding the expiration value to the
idle timestamp each time rather than keeping track of the time in the
past before which the idle timestamp must go to be expired. This is
much easier to read.

(6) Ignore the timeouts if the net namespace is dead.

(7) Restart the service reaper work item rather the client reaper.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Delay terminal ACK transmission on a client call

Delay terminal ACK transmission on a client call by deferring it to the
connection processor. This allows it to be skipped if we can send the next
call instead, the first DATA packet of which will implicitly ack this call.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Fix IPv6 support

Fix IPv6 support in AF_RXRPC in the following ways:

(1) When extracting the address from a received IPv4 packet, if the local
transport socket is open for IPv6 then fill out the sockaddr_rxrpc
struct for an IPv4-mapped-to-IPv6 AF_INET6 transport address instead
of an AF_INET one.

(2) When sending CHALLENGE or RESPONSE packets, the transport length needs
to be set from the sockaddr_rxrpc::transport_len field rather than
sizeof() on the IPv4 transport address.

(3) When processing an IPv4 ICMP packet received by an IPv6 socket, set up
the address correctly before searching for the affected peer.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Cache the congestion window setting

Cache the congestion window setting that was determined during a call's
transmission phase when it finishes so that it can be used by the next call
to the same peer, thereby shortcutting the slow-start algorithm.

The value is stored in the rxrpc_peer struct and is accessed without
locking. Each call takes the value that happens to be there when it starts
and just overwrites the value when it finishes.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

rxrpc: Separate the connection's protocol service ID from the lookup ID

Keep the rxrpc_connection struct's idea of the service ID that is exposed
in the protocol separate from the service ID that's used as a lookup key.

This allows the protocol service ID on a client connection to get upgraded
without making the connection unfindable for other client calls that also
would like to use the upgraded connection.

The connection's actual service ID is then returned through recvmsg() by
way of msg_name.

Whilst we're at it, we get rid of the last_service_id field from each
channel. The service ID is per-connection, not per-call and an entire
connection is upgraded in one go.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Support network namespacing

Support network namespacing in AF_RXRPC with the following changes:

(1) All the local endpoint, peer and call lists, locks, counters, etc. are
moved into the per-namespace record.

(2) All the connection tracking is moved into the per-namespace record
with the exception of the client connection ID tree, which is kept
global so that connection IDs are kept unique per-machine.

(3) Each namespace gets its own epoch. This allows each network namespace
to pretend to be a separate client machine.

(4) The /proc/net/rxrpc_xxx files are now called /proc/net/rxrpc/xxx and
the contents reflect the namespace.

fs/afs/ should be okay with this patch as it explicitly requires the current
net namespace to be init_net to permit a mount to proceed at the moment. It
will, however, need updating so that cells, IP addresses and DNS records are
per-namespace also.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

rxrpc: Add some more tracing

Add the following extra tracing information:

(1) Modify the rxrpc_transmit tracepoint to record the Tx window size as
this is varied by the slow-start algorithm.

(2) Modify the rxrpc_rx_ack tracepoint to record more information from
received ACK packets.

(3) Add an rxrpc_rx_data tracepoint to record the information in DATA
packets.

(4) Add an rxrpc_disconnect_call tracepoint to record call disconnection,
including the reason the call was disconnected.

(5) Add an rxrpc_improper_term tracepoint to record implicit termination
of a call by a client either by starting a new call on a particular
connection channel without first transmitting the final ACK for the
previous call.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Don't store the rxrpc header in the Tx queue sk_buffs

Don't store the rxrpc protocol header in sk_buffs on the transmit queue,
but rather generate it on the fly and pass it to kernel_sendmsg() as a
separate iov. This reduces the amount of storage required.

Note that the security header is still stored in the sk_buff as it may get
encrypted along with the data (and doesn't change with each transmission).

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Add connection tracepoint and client conn state tracepoint

Add a pair of tracepoints, one to track rxrpc_connection struct ref
counting and the other to track the client connection cache state.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Make IPv6 support conditional on CONFIG_IPV6

Add CONFIG_AF_RXRPC_IPV6 and make the IPv6 support code conditional on it.
This is then made conditional on CONFIG_IPV6.

Without this, the following can be seen:

net/built-in.o: In function `rxrpc_init_peer':
>> peer_object.c:(.text+0x18c3c8): undefined reference to `ip6_route_output_flags'

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

rxrpc: Add IPv6 support

Add IPv6 support to AF_RXRPC. With this, AF_RXRPC sockets can be created:

service = socket(AF_RXRPC, SOCK_DGRAM, PF_INET6);

instead of:

service = socket(AF_RXRPC, SOCK_DGRAM, PF_INET);

The AFS filesystem doesn't support IPv6 at the moment, though, since that
requires upgrades to some of the RPC calls.

Note that a good portion of this patch is replacing "%pI4:%u" in print
statements with "%pISpc" which is able to handle both protocols and print
the port.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Rewrite the data and ack handling code

Rewrite the data and ack handling code such that:

(1) Parsing of received ACK and ABORT packets and the distribution and the
filing of DATA packets happens entirely within the data_ready context
called from the UDP socket. This allows us to process and discard ACK
and ABORT packets much more quickly (they're no longer stashed on a
queue for a background thread to process).

(2) We avoid calling skb_clone(), pskb_pull() and pskb_trim(). We instead
keep track of the offset and length of the content of each packet in
the sk_buff metadata. This means we don't do any allocation in the
receive path.

(3) Jumbo DATA packet parsing is now done in data_ready context. Rather
than cloning the packet once for each subpacket and pulling/trimming
it, we file the packet multiple times with an annotation for each
indicating which subpacket is there. From that we can directly
calculate the offset and length.

(4) A call's receive queue can be accessed without taking locks (memory
barriers do have to be used, though).

(5) Incoming calls are set up from preallocated resources and immediately
made live. They can than have packets queued upon them and ACKs
generated. If insufficient resources exist, DATA packet #1 is given a
BUSY reply and other DATA packets are discarded).

(6) sk_buffs no longer take a ref on their parent call.

To make this work, the following changes are made:

(1) Each call's receive buffer is now a circular buffer of sk_buff
pointers (rxtx_buffer) rather than a number of sk_buff_heads spread
between the call and the socket. This permits each sk_buff to be in
the buffer multiple times. The receive buffer is reused for the
transmit buffer.

(2) A circular buffer of annotations (rxtx_annotations) is kept parallel
to the data buffer. Transmission phase annotations indicate whether a
buffered packet has been ACK'd or not and whether it needs
retransmission.

Receive phase annotations indicate whether a slot holds a whole packet
or a jumbo subpacket and, if the latter, which subpacket. They also
note whether the packet has been decrypted in place.

(3) DATA packet window tracking is much simplified. Each phase has just
two numbers representing the window (rx_hard_ack/rx_top and
tx_hard_ack/tx_top).

The hard_ack number is the sequence number before base of the window,
representing the last packet the other side says it has consumed.
hard_ack starts from 0 and the first packet is sequence number 1.

The top number is the sequence number of the highest-numbered packet
residing in the buffer. Packets between hard_ack+1 and top are
soft-ACK'd to indicate they've been received, but not yet consumed.

Four macros, before(), before_eq(), after() and after_eq() are added
to compare sequence numbers within the window. This allows for the
top of the window to wrap when the hard-ack sequence number gets close
to the limit.

Two flags, RXRPC_CALL_RX_LAST and RXRPC_CALL_TX_LAST, are added also
to indicate when rx_top and tx_top point at the packets with the
LAST_PACKET bit set, indicating the end of the phase.

(4) Calls are queued on the socket 'receive queue' rather than packets.
This means that we don't need have to invent dummy packets to queue to
indicate abnormal/terminal states and we don't have to keep metadata
packets (such as ABORTs) around

(5) The offset and length of a (sub)packet's content are now passed to
the verify_packet security op. This is currently expected to decrypt
the packet in place and validate it.

However, there's now nowhere to store the revised offset and length of
the actual data within the decrypted blob (there may be a header and
padding to skip) because an sk_buff may represent multiple packets, so
a locate_data security op is added to retrieve these details from the
sk_buff content when needed.

(6) recvmsg() now has to handle jumbo subpackets, where each subpacket is
individually secured and needs to be individually decrypted. The code
to do this is broken out into rxrpc_recvmsg_data() and shared with the
kernel API. It now iterates over the call's receive buffer rather
than walking the socket receive queue.

Additional changes:

(1) The timers are condensed to a single timer that is set for the soonest
of three timeouts (delayed ACK generation, DATA retransmission and
call lifespan).

(2) Transmission of ACK and ABORT packets is effected immediately from
process-context socket ops/kernel API calls that cause them instead of
them being punted off to a background work item. The data_ready
handler still has to defer to the background, though.

(3) A shutdown op is added to the AF_RXRPC socket so that the AFS
filesystem can shut down the socket and flush its own work items
before closing the socket to deal with any in-progress service calls.

Future additional changes that will need to be considered:

(1) Make sure that a call doesn't hog the front of the queue by receiving
data from the network as fast as userspace is consuming it to the
exclusion of other calls.

(2) Transmit delayed ACKs from within recvmsg() when we've consumed
sufficiently more packets to avoid the background work item needing to
run.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Preallocate peers, conns and calls for incoming service requests

Make it possible for the data_ready handler called from the UDP transport
socket to completely instantiate an rxrpc_call structure and make it
immediately live by preallocating all the memory it might need. The idea
is to cut out the background thread usage as much as possible.

[Note that the preallocated structs are not actually used in this patch -
that will be done in a future patch.]

If insufficient resources are available in the preallocation buffers, it
will be possible to discard the DATA packet in the data_ready handler or
schedule a BUSY packet without the need to schedule an attempt at
allocation in a background thread.

To this end:

(1) Preallocate rxrpc_peer, rxrpc_connection and rxrpc_call structs to a
maximum number each of the listen backlog size. The backlog size is
limited to a maxmimum of 32. Only this many of each can be in the
preallocation buffer.

(2) For userspace sockets, the preallocation is charged initially by
listen() and will be recharged by accepting or rejecting pending
new incoming calls.

(3) For kernel services {,re,dis}charging of the preallocation buffers is
handled manually. Two notifier callbacks have to be provided before
kernel_listen() is invoked:

(a) An indication that a new call has been instantiated. This can be
used to trigger background recharging.

(b) An indication that a call is being discarded. This is used when
the socket is being released.

A function, rxrpc_kernel_charge_accept() is called by the kernel
service to preallocate a single call. It should be passed the user ID
to be used for that call and a callback to associate the rxrpc call
with the kernel service's side of the ID.

(4) Discard the preallocation when the socket is closed.

(5) Temporarily bump the refcount on the call allocated in
rxrpc_incoming_call() so that rxrpc_release_call() can ditch the
preallocation ref on service calls unconditionally. This will no
longer be necessary once the preallocation is used.

Note that this does not yet control the number of active service calls on a
client - that will come in a later patch.

A future development would be to provide a setsockopt() call that allows a
userspace server to manually charge the preallocation buffer. This would
allow user call IDs to be provided in advance and the awkward manual accept
stage to be bypassed.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Calls should only have one terminal state

Condense the terminal states of a call state machine to a single state,
plus a separate completion type value. The value is then set, along with
error and abort code values, only when the call is transitioned to the
completion state.

Helpers are provided to simplify this.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Improve management and caching of client connection objects

Improve the management and caching of client rxrpc connection objects.
From this point, client connections will be managed separately from service
connections because AF_RXRPC controls the creation and re-use of client
connections but doesn't have that luxury with service connections.

Further, there will be limits on the numbers of client connections that may
be live on a machine. No direct restriction will be placed on the number
of client calls, excepting that each client connection can support a
maximum of four concurrent calls.

Note that, for a number of reasons, we don't want to simply discard a
client connection as soon as the last call is apparently finished:

(1) Security is negotiated per-connection and the context is then shared
between all calls on that connection. The context can be negotiated
again if the connection lapses, but that involves holding up calls
whilst at least two packets are exchanged and various crypto bits are
performed - so we'd ideally like to cache it for a little while at
least.

(2) If a packet goes astray, we will need to retransmit a final ACK or
ABORT packet. To make this work, we need to keep around the
connection details for a little while.

(3) The locally held structures represent some amount of setup time, to be
weighed against their occupation of memory when idle.


To this end, the client connection cache is managed by a state machine on
each connection. There are five states:

(1) INACTIVE - The connection is not held in any list and may not have
been exposed to the world. If it has been previously exposed, it was
discarded from the idle list after expiring.

(2) WAITING - The connection is waiting for the number of client conns to
drop below the maximum capacity. Calls may be in progress upon it
from when it was active and got culled.

The connection is on the rxrpc_waiting_client_conns list which is kept
in to-be-granted order. Culled conns with waiters go to the back of
the queue just like new conns.

(3) ACTIVE - The connection has at least one call in progress upon it, it
may freely grant available channels to new calls and calls may be
waiting on it for channels to become available.

The connection is on the rxrpc_active_client_conns list which is kept
in activation order for culling purposes.

(4) CULLED - The connection got summarily culled to try and free up
capacity. Calls currently in progress on the connection are allowed
to continue, but new calls will have to wait. There can be no waiters
in this state - the conn would have to go to the WAITING state
instead.

(5) IDLE - The connection has no calls in progress upon it and must have
been exposed to the world (ie. the EXPOSED flag must be set). When it
expires, the EXPOSED flag is cleared and the connection transitions to
the INACTIVE state.

The connection is on the rxrpc_idle_client_conns list which is kept in
order of how soon they'll expire.

A connection in the ACTIVE or CULLED state must have at least one active
call upon it; if in the WAITING state it may have active calls upon it;
other states may not have active calls.

As long as a connection remains active and doesn't get culled, it may
continue to process calls - even if there are connections on the wait
queue. This simplifies things a bit and reduces the amount of checking we
need do.


There are a couple flags of relevance to the cache:

(1) EXPOSED - The connection ID got exposed to the world. If this flag is
set, an extra ref is added to the connection preventing it from being
reaped when it has no calls outstanding. This flag is cleared and the
ref dropped when a conn is discarded from the idle list.

(2) DONT_REUSE - The connection should be discarded as soon as possible and
should not be reused.


This commit also provides a number of new settings:

(*) /proc/net/rxrpc/max_client_conns

The maximum number of live client connections. Above this number, new
connections get added to the wait list and must wait for an active
conn to be culled. Culled connections can be reused, but they will go
to the back of the wait list and have to wait.

(*) /proc/net/rxrpc/reap_client_conns

If the number of desired connections exceeds the maximum above, the
active connection list will be culled until there are only this many
left in it.

(*) /proc/net/rxrpc/idle_conn_expiry

The normal expiry time for a client connection, provided there are
fewer than reap_client_conns of them around.

(*) /proc/net/rxrpc/idle_conn_fast_expiry

The expedited expiry time, used when there are more than
reap_client_conns of them around.


Note that I combined the Tx wait queue with the channel grant wait queue to
save space as only one of these should be in use at once.

Note also that, for the moment, the service connection cache still uses the
old connection management code.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Dup the main conn list for the proc interface

The main connection list is used for two independent purposes: primarily it
is used to find connections to reap and secondarily it is used to list
connections in procfs.

Split the procfs list out from the reap list. This allows us to stop using
the reap list for client connections when they acquire a separate
management strategy from service collections.

The client connections will not be on a management single list, and sometimes
won't be on a management list at all. This doesn't leave them floating,
however, as they will also be on an rb-tree rooted on the socket so that the
socket can find them to dispatch calls.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Perform terminal call ACK/ABORT retransmission from conn processor

Perform terminal call ACK/ABORT retransmission in the connection processor
rather than in the call processor. With this change, once last_call is
set, no more incoming packets will be routed to the corresponding call or
any earlier calls on that channel (call IDs must only increase on a channel
on a connection).

Further, if a packet's callNumber is before the last_call ID or a packet is
aimed at successfully completed service call then that packet is discarded
and ignored.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Set connection expiry on idle, not put

Set the connection expiry time when a connection becomes idle rather than
doing this in rxrpc_put_connection(). This makes the put path more
efficient (it is likely to be called occasionally whilst a connection has
outstanding calls because active workqueue items needs to be given a ref).

The time is also preset in the connection allocator in case the connection
never gets used.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Drop channel number field from rxrpc_call struct

Drop the channel number (channel) field from the rxrpc_call struct to
reduce the size of the call struct. The field is redundant: if the call is
attached to a connection, the channel can be obtained from there by AND'ing
with RXRPC_CHANNELMASK.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Use RCU to access a peer's service connection tree

Move to using RCU access to a peer's service connection tree when routing
an incoming packet. This is done using a seqlock to trigger retrying of
the tree walk if a change happened.

Further, we no longer get a ref on the connection looked up in the
data_ready handler unless we queue the connection's work item - and then
only if the refcount > 0.


Note that I'm avoiding the use of a hash table for service connections
because each service connection is addressed by a 62-bit number
(constructed from epoch and connection ID >> 2) that would allow the client
to engage in bucket stuffing, given knowledge of the hash algorithm.
Peers, however, are hashed as the network address is less controllable by
the client. The total number of peers will also be limited in a future
commit.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Move data_ready peer lookup into rxrpc_find_connection()

Move the peer lookup done in input.c by data_ready into
rxrpc_find_connection().

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Maintain an extra ref on a conn for the cache list

Overhaul the usage count accounting for the rxrpc_connection struct to make
it easier to implement RCU access from the data_ready handler.

The problem is that currently we're using a lock to prevent the garbage
collector from trying to clean up a connection that we're contemplating
unidling. We could just stick incoming packets on the connection we find,
but we've then got a problem that we may race when dispatching a work item
to process it as we need to give that a ref to prevent the rxrpc_connection
struct from disappearing in the meantime.

Further, incoming packets may get discarded if attached to an
rxrpc_connection struct that is going away. Whilst this is not a total
disaster - the client will presumably resend - it would delay processing of
the call. This would affect the AFS client filesystem's service manager
operation.

To this end:

(1) We now maintain an extra count on the connection usage count whilst it
is on the connection list. This mean it is not in use when its
refcount is 1.

(2) When trying to reuse an old connection, we only increment the refcount
if it is greater than 0. If it is 0, we replace it in the tree with a
new candidate connection.

(3) Two connection flags are added to indicate whether or not a connection
is in the local's client connection tree (used by sendmsg) or the
peer's service connection tree (used by data_ready). This makes sure
that we don't try and remove a connection if it got replaced.

The flags are tested under lock with the removal operation to prevent
the reaper from killing the rxrpc_connection struct whilst someone
else is trying to effect a replacement.

This could probably be alleviated by using memory barriers between the
flag set/test and the rb_tree ops. The rb_tree op would still need to
be under the lock, however.

(4) When trying to reap an old connection, we try to flip the usage count
from 1 to 0. If it's not 1 at that point, then it must've come back
to life temporarily and we ignore it.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Split service connection code out into its own file

Split the service-specific connection code out into into its own file. The
client-specific code has already been split out. This will leave just the
common code in the original file.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Split client connection code out into its own file

Split the client-specific connection code out into its own file. It will
behave somewhat differently from the service-specific connection code, so
it makes sense to separate them.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Call channels should have separate call number spaces

Each channel on a connection has a separate, independent number space from
which to allocate callNumber values. It is entirely possible, for example,
to have a connection with four active calls, each with call number 1.

Note that the callNumber values for any particular channel don't have to
start at 1, but they are supposed to increment monotonically for that
channel from a client's perspective and may not be reused once the call
number is transmitted (until the epoch cycles all the way back round).

Currently, however, call numbers are allocated on a per-connection basis
and, further, are held in an rb-tree. The rb-tree is redundant as the four
channel pointers in the rxrpc_connection struct are entirely capable of
pointing to all the calls currently in progress on a connection.

To this end, make the following changes:

(1) Handle call number allocation independently per channel.

(2) Get rid of the conn->calls rb-tree. This is overkill as a connection
may have a maximum of four calls in progress at any one time. Use the
pointers in the channels[] array instead, indexed by the channel
number from the packet.

(3) For each channel, save the result of the last call that was in
progress on that channel in conn->channels[] so that the final ACK or
ABORT packet can be replayed if necessary. Any call earlier than that
is just ignored. If we've seen the next call number in a packet, the
last one is most definitely defunct.

(4) When generating a RESPONSE packet for a connection, the call number
counter for each channel must be included in it.

(5) When parsing a RESPONSE packet for a connection, the call number
counters contained therein should be used to set the minimum expected
call numbers on each channel.

To do in future commits:

(1) Replay terminal packets based on the last call stored in
conn->channels[].

(2) Connections should be retired before the callNumber space on any
channel runs out.

(3) A server is expected to disregard or reject any new incoming call that
has a call number less than the current call number counter. The call
number counter for that channel must be advanced to the new call
number.

Note that the server cannot just require that the next call that it
sees on a channel be exactly the call number counter + 1 because then
there's a scenario that could cause a problem: The client transmits a
packet to initiate a connection, the network goes out, the server
sends an ACK (which gets lost), the client sends an ABORT (which also
gets lost); the network then reconnects, the client then reuses the
call number for the next call (it doesn't know the server already saw
the call number), but the server thinks it already has the first
packet of this call (it doesn't know that the client doesn't know that
it saw the call number the first time).

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Add RCU destruction for connections and calls

Add RCU destruction for connections and calls as the RCU lookup from the
transport socket data_ready handler is going to come along shortly.

Whilst we're at it, move the cleanup workqueue flushing and RCU barrierage
into the destruction code for the objects that need it (locals and
connections) and add the extra RCU barrier required for connection cleanup.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Release a call's connection ref on call disconnection

When a call is disconnected, clear the call's pointer to the connection and
release the associated ref on that connection. This means that the call no
longer pins the connection and the connection can be discarded even before
the call is.

As the code currently stands, the call struct is effectively pinned by
userspace until userspace has enacted a recvmsg() to retrieve the final
call state as sk_buffs on the receive queue pin the call to which they're
related because:

(1) The rxrpc_call struct contains the userspace ID that recvmsg() has to
include in the control message buffer to indicate which call is being
referred to. This ID must remain valid until the terminal packet is
completely read and must be invalidated immediately at that point as
userspace is entitled to immediately reuse it.

(2) The final ACK to the reply to a client call isn't sent until the last
data packet is entirely read (it's probably worth altering this in
future to be send the ACK as soon as all the data has been received).


This change requires a bit of rearrangement to make sure that the call
isn't going to try and access the connection again after protocol
completion:

(1) Delete the error link earlier when we're releasing the call. Possibly
network errors should be distributed via connections at the cost of
adding in an access to the rxrpc_connection struct.

(2) Remove the call from the connection's call tree before disconnecting
the call. The call tree needs to be removed anyway and incoming
packets delivered by channel pointer instead.

(3) The release call event should be considered last after all other
events have been processed so that we don't need access to the
connection again.

(4) Move the channel_lock taking from rxrpc_release_call() to
rxrpc_disconnect_call() where it will be required in future.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Turn connection #defines into enums and put outside struct def

Turn the connection event and state #define lists into enums and move
outside of the struct definition.

Whilst we're at it, change _SERVER to _SERVICE in those identifiers and add
EV_ into the event name to distinguish them from flags and states.

Also add a symbol indicating the number of states and use that in the state
text array.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Avoid using stack memory in SG lists in rxkad

rxkad uses stack memory in SG lists which would not work if stacks were
allocated from vmalloc memory. In fact, in most cases this isn't even
necessary as the stack memory ends up getting copied over to kmalloc
memory.

This patch eliminates all the unnecessary stack memory uses by supplying
the final destination directly to the crypto API. In two instances where a
temporary buffer is actually needed we also switch use a scratch area in
the rxrpc_call struct (only one DATA packet will be being secured or
verified at a time).

Finally there is no need to split a split-page buffer into two SG entries
so code dealing with that has been removed.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Check the source of a packet to a client conn

When looking up a client connection to which to route a packet, we need to
check that the packet came from the correct source so that a peer can't try
to muck around with another peer's connection.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Fix some sparse errors

Fix the following sparse errors:

../net/rxrpc/conn_object.c:77:17: warning: incorrect type in assignment (different base types)
../net/rxrpc/conn_object.c:77:17: expected restricted __be32 [usertype] call_id
../net/rxrpc/conn_object.c:77:17: got unsigned int [unsigned] [usertype] call_id
../net/rxrpc/conn_object.c:84:21: warning: restricted __be32 degrades to integer
../net/rxrpc/conn_object.c:86:26: warning: restricted __be32 degrades to integer
../net/rxrpc/conn_object.c:357:15: warning: incorrect type in assignment (different base types)
../net/rxrpc/conn_object.c:357:15: expected restricted __be32 [usertype] epoch
../net/rxrpc/conn_object.c:357:15: got unsigned int [unsigned] [usertype] epoch
../net/rxrpc/conn_object.c:369:21: warning: restricted __be32 degrades to integer
../net/rxrpc/conn_object.c:371:26: warning: restricted __be32 degrades to integer
../net/rxrpc/conn_object.c:411:21: warning: restricted __be32 degrades to integer
../net/rxrpc/conn_object.c:413:26: warning: restricted __be32 degrades to integer

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Kill off the rxrpc_transport struct

The rxrpc_transport struct is now redundant, given that the rxrpc_peer
struct is now per peer port rather than per peer host, so get rid of it.

Service connection lists are transferred to the rxrpc_peer struct, as is
the conn_lock. Previous patches moved the client connection handling out
of the rxrpc_transport struct and discarded the connection bundling code.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Kill the client connection bundle concept

Kill off the concept of maintaining a bundle of connections to a particular
target service to increase the number of call slots available for any
beyond four for that service (there are four call slots per connection).

This will make cleaning up the connection handling code easier and
facilitate removal of the rxrpc_transport struct. Bundling can be
reintroduced later if necessary.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Provide more refcount helper functions

Provide refcount helper functions for connections so that the code doesn't
touch local or connection usage counts directly.

Also make it such that local and peer put functions can take a NULL
pointer.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Use IDR to allocate client conn IDs on a machine-wide basis

Use the IDR facility to allocate client connection IDs on a machine-wide
basis so that each client connection has a unique identifier. When the
connection ID space wraps, we advance the epoch by 1, thereby effectively
having a 62-bit ID space. The IDR facility is then used to look up client
connections during incoming packet routing instead of using an rbtree
rooted on the transport.

This change allows for the removal of the transport in the future and also
means that client connections can be looked up directly in the data-ready
handler by connection ID.

The ID management code is placed in a new file, conn-client.c, to which all
the client connection-specific code will eventually move.

Note that the IDR tree gets very expensive on memory if the connection IDs
are widely scattered throughout the number space, so we shall need to
retire connections that have, say, an ID more than four times the maximum
number of client conns away from the current allocation point to try and
keep the IDs concentrated. We will also need to retire connections from an
old epoch.

Also note that, for the moment, a pointer to the transport has to be passed
through into the ID allocation function so that we can take a BH lock to
prevent a locking issue against in-BH lookup of client connections. This
will go away later when RCU is used for server connections also.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: rxrpc_connection_lock shouldn't be a BH lock, but conn_lock is

rxrpc_connection_lock shouldn't be accessed as a BH-excluding lock. It's
only accessed in a few places and none of those are in BH-context.

rxrpc_transport::conn_lock, however, *is* a BH-excluding lock and should be
accessed so consistently.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Pass sk_buff * rather than rxrpc_host_header * to functions

Pass a pointer to struct sk_buff rather than struct rxrpc_host_header to
functions so that they can in the future get at transport protocol parameters
rather than just RxRPC parameters.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Fix exclusive connection handling

"Exclusive connections" are meant to be used for a single client call and
then scrapped. The idea is to limit the use of the negotiated security
context. The current code, however, isn't doing this: it is instead
restricting the socket to a single virtual connection and doing all the
calls over that.

This is changed such that the socket no longer maintains a special virtual
connection over which it will do all the calls, but rather gets a new one
each time a new exclusive call is made.

Further, using a socket option for this is a poor choice. It should be
done on sendmsg with a control message marker instead so that calls can be
marked exclusive individually. To that end, add RXRPC_EXCLUSIVE_CALL
which, if passed to sendmsg() as a control message element, will cause the
call to be done on an single-use connection.

The socket option (RXRPC_EXCLUSIVE_CONNECTION) still exists and, if set,
will override any lack of RXRPC_EXCLUSIVE_CALL being specified so that
programs using the setsockopt() will appear to work the same.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Use structs to hold connection params and protocol info

Define and use a structure to hold connection parameters. This makes it
easier to pass multiple connection parameters around.

Define and use a structure to hold protocol information used to hash a
connection for lookup on incoming packet. Most of these fields will be
disposed of eventually, including the duplicate local pointer.

Whilst we're at it rename "proto" to "family" when referring to a protocol
family.

Signed-off-by: David Howells <dhowells@redhat.com>

rxrpc: Rename files matching ar-*.c to git rid of the "ar-" prefix

Rename files matching net/rxrpc/ar-*.c to get rid of the "ar-" prefix.
This will aid splitting those files by making easier to come up with new
names.

Note that the not all files are simply renamed from ar-X.c to X.c. The
following exceptions are made:

(*) ar-call.c -> call_object.c
ar-ack.c -> call_event.c

call_object.c is going to contain the core of the call object
handling. Call event handling is all going to be in call_event.c.

(*) ar-accept.c -> call_accept.c

Incoming call handling is going to be here.

(*) ar-connection.c -> conn_object.c
ar-connevent.c -> conn_event.c

The former file is going to have the basic connection object handling,
but there will likely be some differentiation between client
connections and service connections in additional files later. The
latter file will have all the connection-level event handling.

(*) ar-local.c -> local_object.c

This will have the local endpoint object handling code. The local
endpoint event handling code will later be split out into
local_event.c.

(*) ar-peer.c -> peer_object.c

This will have the peer endpoint object handling code. Peer event
handling code will be placed in peer_event.c (for the moment, there is
none).

(*) ar-error.c -> peer_event.c

This will become the peer event handling code, though for the moment
it's actually driven from the local endpoint's perspective.

Note that I haven't renamed ar-transport.c to transport_object.c as the
intention is to delete it when the rxrpc_transport struct is excised.

The only file that actually has its contents changed is net/rxrpc/Makefile.

net/rxrpc/ar-internal.h will need its section marker comments updating, but
I'll do that in a separate patch to make it easier for git to follow the
history across the rename. I may also want to rename ar-internal.h at some
point - but that would mean updating all the #includes and I'd rather do
that in a separate step.

Signed-off-by: David Howells <dhowells@redhat.com.