leandrof/linux
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
62259ac4b3
linux/net/rxrpc/call_accept.c
David Howells 8d94aa381d rxrpc: Calls shouldn't hold socket refs 
rxrpc calls shouldn't hold refs on the sock struct.  This was done so that
the socket wouldn't go away whilst the call was in progress, such that the
call could reach the socket's queues.

However, we can mark the socket as requiring an RCU release and rely on the
RCU read lock.

To make this work, we do:

 (1) rxrpc_release_call() removes the call's call user ID.  This is now
     only called from socket operations and not from the call processor:

	rxrpc_accept_call() / rxrpc_kernel_accept_call()
	rxrpc_reject_call() / rxrpc_kernel_reject_call()
	rxrpc_kernel_end_call()
	rxrpc_release_calls_on_socket()
	rxrpc_recvmsg()

     Though it is also called in the cleanup path of
     rxrpc_accept_incoming_call() before we assign a user ID.

 (2) Pass the socket pointer into rxrpc_release_call() rather than getting
     it from the call so that we can get rid of uninitialised calls.

 (3) Fix call processor queueing to pass a ref to the work queue and to
     release that ref at the end of the processor function (or to pass it
     back to the work queue if we have to requeue).

 (4) Skip out of the call processor function asap if the call is complete
     and don't requeue it if the call is complete.

 (5) Clean up the call immediately that the refcount reaches 0 rather than
     trying to defer it.  Actual deallocation is deferred to RCU, however.

 (6) Don't hold socket refs for allocated calls.

 (7) Use the RCU read lock when queueing a message on a socket and treat
     the call's socket pointer according to RCU rules and check it for
     NULL.

     We also need to use the RCU read lock when viewing a call through
     procfs.

 (8) Transmit the final ACK/ABORT to a client call in rxrpc_release_call()
     if this hasn't been done yet so that we can then disconnect the call.
     Once the call is disconnected, it won't have any access to the
     connection struct and the UDP socket for the call work processor to be
     able to send the ACK.  Terminal retransmission will be handled by the
     connection processor.

 (9) Release all calls immediately on the closing of a socket rather than
     trying to defer this.  Incomplete calls will be aborted.

The call refcount model is much simplified.  Refs are held on the call by:

 (1) A socket's user ID tree.

 (2) A socket's incoming call secureq and acceptq.

 (3) A kernel service that has a call in progress.

 (4) A queued call work processor.  We have to take care to put any call
     that we failed to queue.

 (5) sk_buffs on a socket's receive queue.  A future patch will get rid of
     this.

Whilst we're at it, we can do:

 (1) Get rid of the RXRPC_CALL_EV_RELEASE event.  Release is now done
     entirely from the socket routines and never from the call's processor.

 (2) Get rid of the RXRPC_CALL_DEAD state.  Calls now end in the
     RXRPC_CALL_COMPLETE state.

 (3) Get rid of the rxrpc_call::destroyer work item.  Calls are now torn
     down when their refcount reaches 0 and then handed over to RCU for
     final cleanup.

 (4) Get rid of the rxrpc_call::deadspan timer.  Calls are cleaned up
     immediately they're finished with and don't hang around.
     Post-completion retransmission is handled by the connection processor
     once the call is disconnected.

 (5) Get rid of the dead call expiry setting as there's no longer a timer
     to set.

 (6) rxrpc_destroy_all_calls() can just check that the call list is empty.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-07 15:33:20 +01:00

453 lines
11 KiB
C
Raw Blame History

/* incoming call handling
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* 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.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/net.h>
#include <linux/skbuff.h>
#include <linux/errqueue.h>
#include <linux/udp.h>
#include <linux/in.h>
#include <linux/in6.h>
#include <linux/icmp.h>
#include <linux/gfp.h>
#include <net/sock.h>
#include <net/af_rxrpc.h>
#include <net/ip.h>
#include "ar-internal.h"
/*
* generate a connection-level abort
*/
static int rxrpc_busy(struct rxrpc_local *local, struct sockaddr_rxrpc *srx,
struct rxrpc_wire_header *whdr)
{
struct msghdr msg;
struct kvec iov[1];
size_t len;
int ret;
_enter("%d,,", local->debug_id);
whdr->type = RXRPC_PACKET_TYPE_BUSY;
whdr->serial = htonl(1);
msg.msg_name = &srx->transport.sin;
msg.msg_namelen = sizeof(srx->transport.sin);
msg.msg_control = NULL;
msg.msg_controllen = 0;
msg.msg_flags = 0;
iov[0].iov_base = whdr;
iov[0].iov_len = sizeof(*whdr);
len = iov[0].iov_len;
_proto("Tx BUSY %%1");
ret = kernel_sendmsg(local->socket, &msg, iov, 1, len);
if (ret < 0) {
_leave(" = -EAGAIN [sendmsg failed: %d]", ret);
return -EAGAIN;
}
_leave(" = 0");
return 0;
}
/*
* accept an incoming call that needs peer, transport and/or connection setting
* up
*/
static int rxrpc_accept_incoming_call(struct rxrpc_local *local,
struct rxrpc_sock *rx,
struct sk_buff *skb,
struct sockaddr_rxrpc *srx)
{
struct rxrpc_connection *conn;
struct rxrpc_skb_priv *sp, *nsp;
struct rxrpc_call *call;
struct sk_buff *notification;
int ret;
_enter("");
sp = rxrpc_skb(skb);
/* get a notification message to send to the server app */
notification = alloc_skb(0, GFP_NOFS);
if (!notification) {
_debug("no memory");
ret = -ENOMEM;
goto error_nofree;
}
rxrpc_new_skb(notification);
notification->mark = RXRPC_SKB_MARK_NEW_CALL;
conn = rxrpc_incoming_connection(local, srx, skb);
if (IS_ERR(conn)) {
_debug("no conn");
ret = PTR_ERR(conn);
goto error;
}
call = rxrpc_incoming_call(rx, conn, skb);
rxrpc_put_connection(conn);
if (IS_ERR(call)) {
_debug("no call");
ret = PTR_ERR(call);
goto error;
}
/* attach the call to the socket */
read_lock_bh(&local->services_lock);
if (rx->sk.sk_state == RXRPC_CLOSE)
goto invalid_service;
write_lock(&rx->call_lock);
if (!test_and_set_bit(RXRPC_CALL_INIT_ACCEPT, &call->flags)) {
rxrpc_get_call(call, rxrpc_call_got);
spin_lock(&call->conn->state_lock);
if (sp->hdr.securityIndex > 0 &&
call->conn->state == RXRPC_CONN_SERVICE_UNSECURED) {
_debug("await conn sec");
list_add_tail(&call->accept_link, &rx->secureq);
call->conn->state = RXRPC_CONN_SERVICE_CHALLENGING;
set_bit(RXRPC_CONN_EV_CHALLENGE, &call->conn->events);
rxrpc_queue_conn(call->conn);
} else {
_debug("conn ready");
call->state = RXRPC_CALL_SERVER_ACCEPTING;
list_add_tail(&call->accept_link, &rx->acceptq);
rxrpc_get_call_for_skb(call, notification);
nsp = rxrpc_skb(notification);
nsp->call = call;
ASSERTCMP(atomic_read(&call->usage), >=, 3);
_debug("notify");
spin_lock(&call->lock);
ret = rxrpc_queue_rcv_skb(call, notification, true,
false);
spin_unlock(&call->lock);
notification = NULL;
BUG_ON(ret < 0);
}
spin_unlock(&call->conn->state_lock);
_debug("queued");
}
write_unlock(&rx->call_lock);
_debug("process");
rxrpc_fast_process_packet(call, skb);
_debug("done");
read_unlock_bh(&local->services_lock);
rxrpc_free_skb(notification);
rxrpc_put_call(call, rxrpc_call_put);
_leave(" = 0");
return 0;
invalid_service:
_debug("invalid");
read_unlock_bh(&local->services_lock);
rxrpc_release_call(rx, call);
rxrpc_put_call(call, rxrpc_call_put);
ret = -ECONNREFUSED;
error:
rxrpc_free_skb(notification);
error_nofree:
_leave(" = %d", ret);
return ret;
}
/*
* accept incoming calls that need peer, transport and/or connection setting up
* - the packets we get are all incoming client DATA packets that have seq == 1
*/
void rxrpc_accept_incoming_calls(struct rxrpc_local *local)
{
struct rxrpc_skb_priv *sp;
struct sockaddr_rxrpc srx;
struct rxrpc_sock *rx;
struct rxrpc_wire_header whdr;
struct sk_buff *skb;
int ret;
_enter("%d", local->debug_id);
skb = skb_dequeue(&local->accept_queue);
if (!skb) {
_leave("\n");
return;
}
_net("incoming call skb %p", skb);
rxrpc_see_skb(skb);
sp = rxrpc_skb(skb);
/* Set up a response packet header in case we need it */
whdr.epoch = htonl(sp->hdr.epoch);
whdr.cid = htonl(sp->hdr.cid);
whdr.callNumber = htonl(sp->hdr.callNumber);
whdr.seq = htonl(sp->hdr.seq);
whdr.serial = 0;
whdr.flags = 0;
whdr.type = 0;
whdr.userStatus = 0;
whdr.securityIndex = sp->hdr.securityIndex;
whdr._rsvd = 0;
whdr.serviceId = htons(sp->hdr.serviceId);
if (rxrpc_extract_addr_from_skb(&srx, skb) < 0)
goto drop;
/* get the socket providing the service */
read_lock_bh(&local->services_lock);
list_for_each_entry(rx, &local->services, listen_link) {
if (rx->srx.srx_service == sp->hdr.serviceId &&
rx->sk.sk_state != RXRPC_CLOSE)
goto found_service;
}
read_unlock_bh(&local->services_lock);
goto invalid_service;
found_service:
_debug("found service %hd", rx->srx.srx_service);
if (sk_acceptq_is_full(&rx->sk))
goto backlog_full;
sk_acceptq_added(&rx->sk);
read_unlock_bh(&local->services_lock);
ret = rxrpc_accept_incoming_call(local, rx, skb, &srx);
if (ret < 0)
sk_acceptq_removed(&rx->sk);
switch (ret) {
case -ECONNRESET: /* old calls are ignored */
case -ECONNABORTED: /* aborted calls are reaborted or ignored */
case 0:
return;
case -ECONNREFUSED:
goto invalid_service;
case -EBUSY:
goto busy;
case -EKEYREJECTED:
goto security_mismatch;
default:
BUG();
}
backlog_full:
read_unlock_bh(&local->services_lock);
busy:
rxrpc_busy(local, &srx, &whdr);
rxrpc_free_skb(skb);
return;
drop:
rxrpc_free_skb(skb);
return;
invalid_service:
skb->priority = RX_INVALID_OPERATION;
rxrpc_reject_packet(local, skb);
return;
/* can't change connection security type mid-flow */
security_mismatch:
skb->priority = RX_PROTOCOL_ERROR;
rxrpc_reject_packet(local, skb);
return;
}
/*
* handle acceptance of a call by userspace
* - assign the user call ID to the call at the front of the queue
*/
struct rxrpc_call *rxrpc_accept_call(struct rxrpc_sock *rx,
unsigned long user_call_ID,
rxrpc_notify_rx_t notify_rx)
{
struct rxrpc_call *call;
struct rb_node *parent, **pp;
int ret;
_enter(",%lx", user_call_ID);
ASSERT(!irqs_disabled());
write_lock(&rx->call_lock);
ret = -ENODATA;
if (list_empty(&rx->acceptq))
goto out;
/* check the user ID isn't already in use */
ret = -EBADSLT;
pp = &rx->calls.rb_node;
parent = NULL;
while (*pp) {
parent = *pp;
call = rb_entry(parent, struct rxrpc_call, sock_node);
if (user_call_ID < call->user_call_ID)
pp = &(*pp)->rb_left;
else if (user_call_ID > call->user_call_ID)
pp = &(*pp)->rb_right;
else
goto out;
}
/* dequeue the first call and check it's still valid */
call = list_entry(rx->acceptq.next, struct rxrpc_call, accept_link);
list_del_init(&call->accept_link);
sk_acceptq_removed(&rx->sk);
rxrpc_see_call(call);
write_lock_bh(&call->state_lock);
switch (call->state) {
case RXRPC_CALL_SERVER_ACCEPTING:
call->state = RXRPC_CALL_SERVER_RECV_REQUEST;
break;
case RXRPC_CALL_COMPLETE:
ret = call->error;
goto out_release;
default:
BUG();
}
/* formalise the acceptance */
rxrpc_get_call(call, rxrpc_call_got_userid);
call->notify_rx = notify_rx;
call->user_call_ID = user_call_ID;
rb_link_node(&call->sock_node, parent, pp);
rb_insert_color(&call->sock_node, &rx->calls);
if (test_and_set_bit(RXRPC_CALL_HAS_USERID, &call->flags))
BUG();
if (test_and_set_bit(RXRPC_CALL_EV_ACCEPTED, &call->events))
BUG();
write_unlock_bh(&call->state_lock);
write_unlock(&rx->call_lock);
rxrpc_queue_call(call);
_leave(" = %p{%d}", call, call->debug_id);
return call;
out_release:
write_unlock_bh(&call->state_lock);
write_unlock(&rx->call_lock);
_debug("release %p", call);
rxrpc_release_call(rx, call);
_leave(" = %d", ret);
return ERR_PTR(ret);
out:
write_unlock(&rx->call_lock);
_leave(" = %d", ret);
return ERR_PTR(ret);
}
/*
* Handle rejection of a call by userspace
* - reject the call at the front of the queue
*/
int rxrpc_reject_call(struct rxrpc_sock *rx)
{
struct rxrpc_call *call;
int ret;
_enter("");
ASSERT(!irqs_disabled());
write_lock(&rx->call_lock);
ret = -ENODATA;
if (list_empty(&rx->acceptq)) {
write_unlock(&rx->call_lock);
_leave(" = -ENODATA");
return -ENODATA;
}
/* dequeue the first call and check it's still valid */
call = list_entry(rx->acceptq.next, struct rxrpc_call, accept_link);
list_del_init(&call->accept_link);
sk_acceptq_removed(&rx->sk);
rxrpc_see_call(call);
write_lock_bh(&call->state_lock);
switch (call->state) {
case RXRPC_CALL_SERVER_ACCEPTING:
__rxrpc_set_call_completion(call, RXRPC_CALL_SERVER_BUSY,
0, ECONNABORTED);
if (test_and_set_bit(RXRPC_CALL_EV_REJECT_BUSY, &call->events))
rxrpc_queue_call(call);
ret = 0;
break;
case RXRPC_CALL_COMPLETE:
ret = call->error;
break;
default:
BUG();
}
write_unlock_bh(&call->state_lock);
write_unlock(&rx->call_lock);
rxrpc_release_call(rx, call);
_leave(" = %d", ret);
return ret;
}
/**
* rxrpc_kernel_accept_call - Allow a kernel service to accept an incoming call
* @sock: The socket on which the impending call is waiting
* @user_call_ID: The tag to attach to the call
* @notify_rx: Where to send notifications instead of socket queue
*
* Allow a kernel service to accept an incoming call, assuming the incoming
* call is still valid. The caller should immediately trigger their own
* notification as there must be data waiting.
*/
struct rxrpc_call *rxrpc_kernel_accept_call(struct socket *sock,
unsigned long user_call_ID,
rxrpc_notify_rx_t notify_rx)
{
struct rxrpc_call *call;
_enter(",%lx", user_call_ID);
call = rxrpc_accept_call(rxrpc_sk(sock->sk), user_call_ID, notify_rx);
_leave(" = %p", call);
return call;
}
EXPORT_SYMBOL(rxrpc_kernel_accept_call);
/**
* rxrpc_kernel_reject_call - Allow a kernel service to reject an incoming call
* @sock: The socket on which the impending call is waiting
*
* Allow a kernel service to reject an incoming call with a BUSY message,
* assuming the incoming call is still valid.
*/
int rxrpc_kernel_reject_call(struct socket *sock)
{
int ret;
_enter("");
ret = rxrpc_reject_call(rxrpc_sk(sock->sk));
_leave(" = %d", ret);
return ret;
}
EXPORT_SYMBOL(rxrpc_kernel_reject_call);
Reference in New Issue View Git Blame Copy Permalink