diff options
Diffstat (limited to 'net/rxrpc/call_accept.c')
| -rw-r--r-- | net/rxrpc/call_accept.c | 667 |
1 files changed, 667 insertions, 0 deletions
diff --git a/net/rxrpc/call_accept.c b/net/rxrpc/call_accept.c new file mode 100644 index 000000000..7ecfbff1f --- /dev/null +++ b/net/rxrpc/call_accept.c @@ -0,0 +1,667 @@ +/* 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 <linux/circ_buf.h> +#include <net/sock.h> +#include <net/af_rxrpc.h> +#include <net/ip.h> +#include "ar-internal.h" + +static void rxrpc_dummy_notify(struct sock *sk, struct rxrpc_call *call, + unsigned long user_call_ID) +{ +} + +/* + * Preallocate a single service call, connection and peer and, if possible, + * give them a user ID and attach the user's side of the ID to them. + */ +static int rxrpc_service_prealloc_one(struct rxrpc_sock *rx, + struct rxrpc_backlog *b, + rxrpc_notify_rx_t notify_rx, + rxrpc_user_attach_call_t user_attach_call, + unsigned long user_call_ID, gfp_t gfp, + unsigned int debug_id) +{ + const void *here = __builtin_return_address(0); + struct rxrpc_call *call; + struct rxrpc_net *rxnet = rxrpc_net(sock_net(&rx->sk)); + int max, tmp; + unsigned int size = RXRPC_BACKLOG_MAX; + unsigned int head, tail, call_head, call_tail; + + max = rx->sk.sk_max_ack_backlog; + tmp = rx->sk.sk_ack_backlog; + if (tmp >= max) { + _leave(" = -ENOBUFS [full %u]", max); + return -ENOBUFS; + } + max -= tmp; + + /* We don't need more conns and peers than we have calls, but on the + * other hand, we shouldn't ever use more peers than conns or conns + * than calls. + */ + call_head = b->call_backlog_head; + call_tail = READ_ONCE(b->call_backlog_tail); + tmp = CIRC_CNT(call_head, call_tail, size); + if (tmp >= max) { + _leave(" = -ENOBUFS [enough %u]", tmp); + return -ENOBUFS; + } + max = tmp + 1; + + head = b->peer_backlog_head; + tail = READ_ONCE(b->peer_backlog_tail); + if (CIRC_CNT(head, tail, size) < max) { + struct rxrpc_peer *peer = rxrpc_alloc_peer(rx->local, gfp); + if (!peer) + return -ENOMEM; + b->peer_backlog[head] = peer; + smp_store_release(&b->peer_backlog_head, + (head + 1) & (size - 1)); + } + + head = b->conn_backlog_head; + tail = READ_ONCE(b->conn_backlog_tail); + if (CIRC_CNT(head, tail, size) < max) { + struct rxrpc_connection *conn; + + conn = rxrpc_prealloc_service_connection(rxnet, gfp); + if (!conn) + return -ENOMEM; + b->conn_backlog[head] = conn; + smp_store_release(&b->conn_backlog_head, + (head + 1) & (size - 1)); + + trace_rxrpc_conn(conn->debug_id, rxrpc_conn_new_service, + atomic_read(&conn->usage), here); + } + + /* Now it gets complicated, because calls get registered with the + * socket here, particularly if a user ID is preassigned by the user. + */ + call = rxrpc_alloc_call(rx, gfp, debug_id); + if (!call) + return -ENOMEM; + call->flags |= (1 << RXRPC_CALL_IS_SERVICE); + call->state = RXRPC_CALL_SERVER_PREALLOC; + + trace_rxrpc_call(call, rxrpc_call_new_service, + atomic_read(&call->usage), + here, (const void *)user_call_ID); + + write_lock(&rx->call_lock); + if (user_attach_call) { + struct rxrpc_call *xcall; + struct rb_node *parent, **pp; + + /* Check the user ID isn't already in use */ + pp = &rx->calls.rb_node; + parent = NULL; + while (*pp) { + parent = *pp; + xcall = rb_entry(parent, struct rxrpc_call, sock_node); + if (user_call_ID < xcall->user_call_ID) + pp = &(*pp)->rb_left; + else if (user_call_ID > xcall->user_call_ID) + pp = &(*pp)->rb_right; + else + goto id_in_use; + } + + call->user_call_ID = user_call_ID; + call->notify_rx = notify_rx; + rxrpc_get_call(call, rxrpc_call_got_kernel); + user_attach_call(call, user_call_ID); + rxrpc_get_call(call, rxrpc_call_got_userid); + rb_link_node(&call->sock_node, parent, pp); + rb_insert_color(&call->sock_node, &rx->calls); + set_bit(RXRPC_CALL_HAS_USERID, &call->flags); + } + + list_add(&call->sock_link, &rx->sock_calls); + + write_unlock(&rx->call_lock); + + rxnet = call->rxnet; + write_lock(&rxnet->call_lock); + list_add_tail(&call->link, &rxnet->calls); + write_unlock(&rxnet->call_lock); + + b->call_backlog[call_head] = call; + smp_store_release(&b->call_backlog_head, (call_head + 1) & (size - 1)); + _leave(" = 0 [%d -> %lx]", call->debug_id, user_call_ID); + return 0; + +id_in_use: + write_unlock(&rx->call_lock); + rxrpc_cleanup_call(call); + _leave(" = -EBADSLT"); + return -EBADSLT; +} + +/* + * Preallocate sufficient service connections, calls and peers to cover the + * entire backlog of a socket. When a new call comes in, if we don't have + * sufficient of each available, the call gets rejected as busy or ignored. + * + * The backlog is replenished when a connection is accepted or rejected. + */ +int rxrpc_service_prealloc(struct rxrpc_sock *rx, gfp_t gfp) +{ + struct rxrpc_backlog *b = rx->backlog; + + if (!b) { + b = kzalloc(sizeof(struct rxrpc_backlog), gfp); + if (!b) + return -ENOMEM; + rx->backlog = b; + } + + if (rx->discard_new_call) + return 0; + + while (rxrpc_service_prealloc_one(rx, b, NULL, NULL, 0, gfp, + atomic_inc_return(&rxrpc_debug_id)) == 0) + ; + + return 0; +} + +/* + * Discard the preallocation on a service. + */ +void rxrpc_discard_prealloc(struct rxrpc_sock *rx) +{ + struct rxrpc_backlog *b = rx->backlog; + struct rxrpc_net *rxnet = rxrpc_net(sock_net(&rx->sk)); + unsigned int size = RXRPC_BACKLOG_MAX, head, tail; + + if (!b) + return; + rx->backlog = NULL; + + /* Make sure that there aren't any incoming calls in progress before we + * clear the preallocation buffers. + */ + spin_lock_bh(&rx->incoming_lock); + spin_unlock_bh(&rx->incoming_lock); + + head = b->peer_backlog_head; + tail = b->peer_backlog_tail; + while (CIRC_CNT(head, tail, size) > 0) { + struct rxrpc_peer *peer = b->peer_backlog[tail]; + rxrpc_put_local(peer->local); + kfree(peer); + tail = (tail + 1) & (size - 1); + } + + head = b->conn_backlog_head; + tail = b->conn_backlog_tail; + while (CIRC_CNT(head, tail, size) > 0) { + struct rxrpc_connection *conn = b->conn_backlog[tail]; + write_lock(&rxnet->conn_lock); + list_del(&conn->link); + list_del(&conn->proc_link); + write_unlock(&rxnet->conn_lock); + kfree(conn); + if (atomic_dec_and_test(&rxnet->nr_conns)) + wake_up_var(&rxnet->nr_conns); + tail = (tail + 1) & (size - 1); + } + + head = b->call_backlog_head; + tail = b->call_backlog_tail; + while (CIRC_CNT(head, tail, size) > 0) { + struct rxrpc_call *call = b->call_backlog[tail]; + rcu_assign_pointer(call->socket, rx); + if (rx->discard_new_call) { + _debug("discard %lx", call->user_call_ID); + rx->discard_new_call(call, call->user_call_ID); + if (call->notify_rx) + call->notify_rx = rxrpc_dummy_notify; + rxrpc_put_call(call, rxrpc_call_put_kernel); + } + rxrpc_call_completed(call); + rxrpc_release_call(rx, call); + rxrpc_put_call(call, rxrpc_call_put); + tail = (tail + 1) & (size - 1); + } + + kfree(b); +} + +/* + * Allocate a new incoming call from the prealloc pool, along with a connection + * and a peer as necessary. + */ +static struct rxrpc_call *rxrpc_alloc_incoming_call(struct rxrpc_sock *rx, + struct rxrpc_local *local, + struct rxrpc_peer *peer, + struct rxrpc_connection *conn, + struct sk_buff *skb) +{ + struct rxrpc_backlog *b = rx->backlog; + struct rxrpc_call *call; + unsigned short call_head, conn_head, peer_head; + unsigned short call_tail, conn_tail, peer_tail; + unsigned short call_count, conn_count; + + /* #calls >= #conns >= #peers must hold true. */ + call_head = smp_load_acquire(&b->call_backlog_head); + call_tail = b->call_backlog_tail; + call_count = CIRC_CNT(call_head, call_tail, RXRPC_BACKLOG_MAX); + conn_head = smp_load_acquire(&b->conn_backlog_head); + conn_tail = b->conn_backlog_tail; + conn_count = CIRC_CNT(conn_head, conn_tail, RXRPC_BACKLOG_MAX); + ASSERTCMP(conn_count, >=, call_count); + peer_head = smp_load_acquire(&b->peer_backlog_head); + peer_tail = b->peer_backlog_tail; + ASSERTCMP(CIRC_CNT(peer_head, peer_tail, RXRPC_BACKLOG_MAX), >=, + conn_count); + + if (call_count == 0) + return NULL; + + if (!conn) { + if (peer && !rxrpc_get_peer_maybe(peer)) + peer = NULL; + if (!peer) { + peer = b->peer_backlog[peer_tail]; + if (rxrpc_extract_addr_from_skb(local, &peer->srx, skb) < 0) + return NULL; + b->peer_backlog[peer_tail] = NULL; + smp_store_release(&b->peer_backlog_tail, + (peer_tail + 1) & + (RXRPC_BACKLOG_MAX - 1)); + + rxrpc_new_incoming_peer(rx, local, peer); + } + + /* Now allocate and set up the connection */ + conn = b->conn_backlog[conn_tail]; + b->conn_backlog[conn_tail] = NULL; + smp_store_release(&b->conn_backlog_tail, + (conn_tail + 1) & (RXRPC_BACKLOG_MAX - 1)); + conn->params.local = rxrpc_get_local(local); + conn->params.peer = peer; + rxrpc_see_connection(conn); + rxrpc_new_incoming_connection(rx, conn, skb); + } else { + rxrpc_get_connection(conn); + } + + /* And now we can allocate and set up a new call */ + call = b->call_backlog[call_tail]; + b->call_backlog[call_tail] = NULL; + smp_store_release(&b->call_backlog_tail, + (call_tail + 1) & (RXRPC_BACKLOG_MAX - 1)); + + rxrpc_see_call(call); + call->conn = conn; + call->peer = rxrpc_get_peer(conn->params.peer); + call->cong_cwnd = call->peer->cong_cwnd; + return call; +} + +/* + * Set up a new incoming call. Called in BH context with the RCU read lock + * held. + * + * If this is for a kernel service, when we allocate the call, it will have + * three refs on it: (1) the kernel service, (2) the user_call_ID tree, (3) the + * retainer ref obtained from the backlog buffer. Prealloc calls for userspace + * services only have the ref from the backlog buffer. We want to pass this + * ref to non-BH context to dispose of. + * + * If we want to report an error, we mark the skb with the packet type and + * abort code and return NULL. + * + * The call is returned with the user access mutex held. + */ +struct rxrpc_call *rxrpc_new_incoming_call(struct rxrpc_local *local, + struct rxrpc_sock *rx, + struct sk_buff *skb) +{ + struct rxrpc_skb_priv *sp = rxrpc_skb(skb); + struct rxrpc_connection *conn; + struct rxrpc_peer *peer = NULL; + struct rxrpc_call *call; + + _enter(""); + + spin_lock(&rx->incoming_lock); + if (rx->sk.sk_state == RXRPC_SERVER_LISTEN_DISABLED || + rx->sk.sk_state == RXRPC_CLOSE) { + trace_rxrpc_abort(0, "CLS", sp->hdr.cid, sp->hdr.callNumber, + sp->hdr.seq, RX_INVALID_OPERATION, ESHUTDOWN); + skb->mark = RXRPC_SKB_MARK_REJECT_ABORT; + skb->priority = RX_INVALID_OPERATION; + _leave(" = NULL [close]"); + call = NULL; + goto out; + } + + /* The peer, connection and call may all have sprung into existence due + * to a duplicate packet being handled on another CPU in parallel, so + * we have to recheck the routing. However, we're now holding + * rx->incoming_lock, so the values should remain stable. + */ + conn = rxrpc_find_connection_rcu(local, skb, &peer); + + call = rxrpc_alloc_incoming_call(rx, local, peer, conn, skb); + if (!call) { + skb->mark = RXRPC_SKB_MARK_REJECT_BUSY; + _leave(" = NULL [busy]"); + call = NULL; + goto out; + } + + trace_rxrpc_receive(call, rxrpc_receive_incoming, + sp->hdr.serial, sp->hdr.seq); + + /* Lock the call to prevent rxrpc_kernel_send/recv_data() and + * sendmsg()/recvmsg() inconveniently stealing the mutex once the + * notification is generated. + * + * The BUG should never happen because the kernel should be well + * behaved enough not to access the call before the first notification + * event and userspace is prevented from doing so until the state is + * appropriate. + */ + if (!mutex_trylock(&call->user_mutex)) + BUG(); + + /* Make the call live. */ + rxrpc_incoming_call(rx, call, skb); + conn = call->conn; + + if (rx->notify_new_call) + rx->notify_new_call(&rx->sk, call, call->user_call_ID); + else + sk_acceptq_added(&rx->sk); + + spin_lock(&conn->state_lock); + switch (conn->state) { + case RXRPC_CONN_SERVICE_UNSECURED: + conn->state = RXRPC_CONN_SERVICE_CHALLENGING; + set_bit(RXRPC_CONN_EV_CHALLENGE, &call->conn->events); + rxrpc_queue_conn(call->conn); + break; + + case RXRPC_CONN_SERVICE: + write_lock(&call->state_lock); + if (call->state < RXRPC_CALL_COMPLETE) { + if (rx->discard_new_call) + call->state = RXRPC_CALL_SERVER_RECV_REQUEST; + else + call->state = RXRPC_CALL_SERVER_ACCEPTING; + } + write_unlock(&call->state_lock); + break; + + case RXRPC_CONN_REMOTELY_ABORTED: + rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED, + conn->abort_code, conn->error); + break; + case RXRPC_CONN_LOCALLY_ABORTED: + rxrpc_abort_call("CON", call, sp->hdr.seq, + conn->abort_code, conn->error); + break; + default: + BUG(); + } + spin_unlock(&conn->state_lock); + + if (call->state == RXRPC_CALL_SERVER_ACCEPTING) + rxrpc_notify_socket(call); + + /* We have to discard the prealloc queue's ref here and rely on a + * combination of the RCU read lock and refs held either by the socket + * (recvmsg queue, to-be-accepted queue or user ID tree) or the kernel + * service to prevent the call from being deallocated too early. + */ + rxrpc_put_call(call, rxrpc_call_put); + + _leave(" = %p{%d}", call, call->debug_id); +out: + spin_unlock(&rx->incoming_lock); + return call; +} + +/* + * handle acceptance of a call by userspace + * - assign the user call ID to the call at the front of the queue + * - called with the socket locked. + */ +struct rxrpc_call *rxrpc_accept_call(struct rxrpc_sock *rx, + unsigned long user_call_ID, + rxrpc_notify_rx_t notify_rx) + __releases(&rx->sk.sk_lock.slock) + __acquires(call->user_mutex) +{ + struct rxrpc_call *call; + struct rb_node *parent, **pp; + int ret; + + _enter(",%lx", user_call_ID); + + ASSERT(!irqs_disabled()); + + write_lock(&rx->call_lock); + + if (list_empty(&rx->to_be_accepted)) { + write_unlock(&rx->call_lock); + release_sock(&rx->sk); + kleave(" = -ENODATA [empty]"); + return ERR_PTR(-ENODATA); + } + + /* check the user ID isn't already in use */ + 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 id_in_use; + } + + /* Dequeue the first call and check it's still valid. We gain + * responsibility for the queue's reference. + */ + call = list_entry(rx->to_be_accepted.next, + struct rxrpc_call, accept_link); + write_unlock(&rx->call_lock); + + /* We need to gain the mutex from the interrupt handler without + * upsetting lockdep, so we have to release it there and take it here. + * We are, however, still holding the socket lock, so other accepts + * must wait for us and no one can add the user ID behind our backs. + */ + if (mutex_lock_interruptible(&call->user_mutex) < 0) { + release_sock(&rx->sk); + kleave(" = -ERESTARTSYS"); + return ERR_PTR(-ERESTARTSYS); + } + + write_lock(&rx->call_lock); + list_del_init(&call->accept_link); + sk_acceptq_removed(&rx->sk); + rxrpc_see_call(call); + + /* Find the user ID insertion point. */ + 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 + BUG(); + } + + 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 */ + call->notify_rx = notify_rx; + call->user_call_ID = user_call_ID; + rxrpc_get_call(call, rxrpc_call_got_userid); + 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(); + + write_unlock_bh(&call->state_lock); + write_unlock(&rx->call_lock); + rxrpc_notify_socket(call); + rxrpc_service_prealloc(rx, GFP_KERNEL); + release_sock(&rx->sk); + _leave(" = %p{%d}", call, call->debug_id); + return call; + +out_release: + _debug("release %p", call); + write_unlock_bh(&call->state_lock); + write_unlock(&rx->call_lock); + rxrpc_release_call(rx, call); + rxrpc_put_call(call, rxrpc_call_put); + goto out; + +id_in_use: + ret = -EBADSLT; + write_unlock(&rx->call_lock); +out: + rxrpc_service_prealloc(rx, GFP_KERNEL); + release_sock(&rx->sk); + _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; + bool abort = false; + int ret; + + _enter(""); + + ASSERT(!irqs_disabled()); + + write_lock(&rx->call_lock); + + if (list_empty(&rx->to_be_accepted)) { + write_unlock(&rx->call_lock); + return -ENODATA; + } + + /* Dequeue the first call and check it's still valid. We gain + * responsibility for the queue's reference. + */ + call = list_entry(rx->to_be_accepted.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_abort_call("REJ", call, 1, RX_USER_ABORT, -ECONNABORTED); + abort = true; + /* fall through */ + case RXRPC_CALL_COMPLETE: + ret = call->error; + goto out_discard; + default: + BUG(); + } + +out_discard: + write_unlock_bh(&call->state_lock); + write_unlock(&rx->call_lock); + if (abort) { + rxrpc_send_abort_packet(call); + rxrpc_release_call(rx, call); + rxrpc_put_call(call, rxrpc_call_put); + } + rxrpc_service_prealloc(rx, GFP_KERNEL); + _leave(" = %d", ret); + return ret; +} + +/* + * rxrpc_kernel_charge_accept - Charge up socket with preallocated calls + * @sock: The socket on which to preallocate + * @notify_rx: Event notification function for the call + * @user_attach_call: Func to attach call to user_call_ID + * @user_call_ID: The tag to attach to the preallocated call + * @gfp: The allocation conditions. + * @debug_id: The tracing debug ID. + * + * Charge up the socket with preallocated calls, each with a user ID. A + * function should be provided to effect the attachment from the user's side. + * The user is given a ref to hold on the call. + * + * Note that the call may be come connected before this function returns. + */ +int rxrpc_kernel_charge_accept(struct socket *sock, + rxrpc_notify_rx_t notify_rx, + rxrpc_user_attach_call_t user_attach_call, + unsigned long user_call_ID, gfp_t gfp, + unsigned int debug_id) +{ + struct rxrpc_sock *rx = rxrpc_sk(sock->sk); + struct rxrpc_backlog *b = rx->backlog; + + if (sock->sk->sk_state == RXRPC_CLOSE) + return -ESHUTDOWN; + + return rxrpc_service_prealloc_one(rx, b, notify_rx, + user_attach_call, user_call_ID, + gfp, debug_id); +} +EXPORT_SYMBOL(rxrpc_kernel_charge_accept); |