1/*
2 * Copyright (c) 2006, 2017 Oracle and/or its affiliates. All rights reserved.
3 *
4 * This software is available to you under a choice of one of two
5 * licenses.  You may choose to be licensed under the terms of the GNU
6 * General Public License (GPL) Version 2, available from the file
7 * COPYING in the main directory of this source tree, or the
8 * OpenIB.org BSD license below:
9 *
10 *     Redistribution and use in source and binary forms, with or
11 *     without modification, are permitted provided that the following
12 *     conditions are met:
13 *
14 *      - Redistributions of source code must retain the above
15 *        copyright notice, this list of conditions and the following
16 *        disclaimer.
17 *
18 *      - Redistributions in binary form must reproduce the above
19 *        copyright notice, this list of conditions and the following
20 *        disclaimer in the documentation and/or other materials
21 *        provided with the distribution.
22 *
23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
24 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
25 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
26 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
27 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
28 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
29 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
30 * SOFTWARE.
31 *
32 */
33#include <linux/kernel.h>
34#include <linux/slab.h>
35#include <linux/in.h>
36#include <net/net_namespace.h>
37#include <net/netns/generic.h>
38#include <linux/ipv6.h>
39
40#include "rds_single_path.h"
41#include "rds.h"
42#include "loop.h"
43
44static DEFINE_SPINLOCK(loop_conns_lock);
45static LIST_HEAD(loop_conns);
46static atomic_t rds_loop_unloading = ATOMIC_INIT(0);
47
48static void rds_loop_set_unloading(void)
49{
50	atomic_set(&rds_loop_unloading, 1);
51}
52
53static bool rds_loop_is_unloading(struct rds_connection *conn)
54{
55	return atomic_read(&rds_loop_unloading) != 0;
56}
57
58/*
59 * This 'loopback' transport is a special case for flows that originate
60 * and terminate on the same machine.
61 *
62 * Connection build-up notices if the destination address is thought of
63 * as a local address by a transport.  At that time it decides to use the
64 * loopback transport instead of the bound transport of the sending socket.
65 *
66 * The loopback transport's sending path just hands the sent rds_message
67 * straight to the receiving path via an embedded rds_incoming.
68 */
69
70/*
71 * Usually a message transits both the sender and receiver's conns as it
72 * flows to the receiver.  In the loopback case, though, the receive path
73 * is handed the sending conn so the sense of the addresses is reversed.
74 */
75static int rds_loop_xmit(struct rds_connection *conn, struct rds_message *rm,
76			 unsigned int hdr_off, unsigned int sg,
77			 unsigned int off)
78{
79	struct scatterlist *sgp = &rm->data.op_sg[sg];
80	int ret = sizeof(struct rds_header) +
81			be32_to_cpu(rm->m_inc.i_hdr.h_len);
82
83	/* Do not send cong updates to loopback */
84	if (rm->m_inc.i_hdr.h_flags & RDS_FLAG_CONG_BITMAP) {
85		rds_cong_map_updated(conn->c_fcong, ~(u64) 0);
86		ret = min_t(int, ret, sgp->length - conn->c_xmit_data_off);
87		goto out;
88	}
89
90	BUG_ON(hdr_off || sg || off);
91
92	rds_inc_init(&rm->m_inc, conn, &conn->c_laddr);
93	/* For the embedded inc. Matching put is in loop_inc_free() */
94	rds_message_addref(rm);
95
96	rds_recv_incoming(conn, &conn->c_laddr, &conn->c_faddr, &rm->m_inc,
97			  GFP_KERNEL);
98
99	rds_send_drop_acked(conn, be64_to_cpu(rm->m_inc.i_hdr.h_sequence),
100			    NULL);
101
102	rds_inc_put(&rm->m_inc);
103out:
104	return ret;
105}
106
107/*
108 * See rds_loop_xmit(). Since our inc is embedded in the rm, we
109 * make sure the rm lives at least until the inc is done.
110 */
111static void rds_loop_inc_free(struct rds_incoming *inc)
112{
113	struct rds_message *rm = container_of(inc, struct rds_message, m_inc);
114
115	rds_message_put(rm);
116}
117
118/* we need to at least give the thread something to succeed */
119static int rds_loop_recv_path(struct rds_conn_path *cp)
120{
121	return 0;
122}
123
124struct rds_loop_connection {
125	struct list_head loop_node;
126	struct rds_connection *conn;
127};
128
129/*
130 * Even the loopback transport needs to keep track of its connections,
131 * so it can call rds_conn_destroy() on them on exit. N.B. there are
132 * 1+ loopback addresses (127.*.*.*) so it's not a bug to have
133 * multiple loopback conns allocated, although rather useless.
134 */
135static int rds_loop_conn_alloc(struct rds_connection *conn, gfp_t gfp)
136{
137	struct rds_loop_connection *lc;
138	unsigned long flags;
139
140	lc = kzalloc(sizeof(struct rds_loop_connection), gfp);
141	if (!lc)
142		return -ENOMEM;
143
144	INIT_LIST_HEAD(&lc->loop_node);
145	lc->conn = conn;
146	conn->c_transport_data = lc;
147
148	spin_lock_irqsave(&loop_conns_lock, flags);
149	list_add_tail(&lc->loop_node, &loop_conns);
150	spin_unlock_irqrestore(&loop_conns_lock, flags);
151
152	return 0;
153}
154
155static void rds_loop_conn_free(void *arg)
156{
157	struct rds_loop_connection *lc = arg;
158	unsigned long flags;
159
160	rdsdebug("lc %p\n", lc);
161	spin_lock_irqsave(&loop_conns_lock, flags);
162	list_del(&lc->loop_node);
163	spin_unlock_irqrestore(&loop_conns_lock, flags);
164	kfree(lc);
165}
166
167static int rds_loop_conn_path_connect(struct rds_conn_path *cp)
168{
169	rds_connect_complete(cp->cp_conn);
170	return 0;
171}
172
173static void rds_loop_conn_path_shutdown(struct rds_conn_path *cp)
174{
175}
176
177void rds_loop_exit(void)
178{
179	struct rds_loop_connection *lc, *_lc;
180	LIST_HEAD(tmp_list);
181
182	rds_loop_set_unloading();
183	synchronize_rcu();
184	/* avoid calling conn_destroy with irqs off */
185	spin_lock_irq(&loop_conns_lock);
186	list_splice(&loop_conns, &tmp_list);
187	INIT_LIST_HEAD(&loop_conns);
188	spin_unlock_irq(&loop_conns_lock);
189
190	list_for_each_entry_safe(lc, _lc, &tmp_list, loop_node) {
191		WARN_ON(lc->conn->c_passive);
192		rds_conn_destroy(lc->conn);
193	}
194}
195
196static void rds_loop_kill_conns(struct net *net)
197{
198	struct rds_loop_connection *lc, *_lc;
199	LIST_HEAD(tmp_list);
200
201	spin_lock_irq(&loop_conns_lock);
202	list_for_each_entry_safe(lc, _lc, &loop_conns, loop_node)  {
203		struct net *c_net = read_pnet(&lc->conn->c_net);
204
205		if (net != c_net)
206			continue;
207		list_move_tail(&lc->loop_node, &tmp_list);
208	}
209	spin_unlock_irq(&loop_conns_lock);
210
211	list_for_each_entry_safe(lc, _lc, &tmp_list, loop_node) {
212		WARN_ON(lc->conn->c_passive);
213		rds_conn_destroy(lc->conn);
214	}
215}
216
217static void __net_exit rds_loop_exit_net(struct net *net)
218{
219	rds_loop_kill_conns(net);
220}
221
222static struct pernet_operations rds_loop_net_ops = {
223	.exit = rds_loop_exit_net,
224};
225
226int rds_loop_net_init(void)
227{
228	return register_pernet_device(&rds_loop_net_ops);
229}
230
231void rds_loop_net_exit(void)
232{
233	unregister_pernet_device(&rds_loop_net_ops);
234}
235
236/*
237 * This is missing .xmit_* because loop doesn't go through generic
238 * rds_send_xmit() and doesn't call rds_recv_incoming().  .listen_stop and
239 * .laddr_check are missing because transport.c doesn't iterate over
240 * rds_loop_transport.
241 */
242struct rds_transport rds_loop_transport = {
243	.xmit			= rds_loop_xmit,
244	.recv_path		= rds_loop_recv_path,
245	.conn_alloc		= rds_loop_conn_alloc,
246	.conn_free		= rds_loop_conn_free,
247	.conn_path_connect	= rds_loop_conn_path_connect,
248	.conn_path_shutdown	= rds_loop_conn_path_shutdown,
249	.inc_copy_to_user	= rds_message_inc_copy_to_user,
250	.inc_free		= rds_loop_inc_free,
251	.t_name			= "loopback",
252	.t_type			= RDS_TRANS_LOOP,
253	.t_unloading		= rds_loop_is_unloading,
254};
255