1// SPDX-License-Identifier: GPL-2.0-or-later
2/* RxRPC remote transport endpoint record management
3 *
4 * Copyright (C) 2007, 2016 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
10#include <linux/module.h>
11#include <linux/net.h>
12#include <linux/skbuff.h>
13#include <linux/udp.h>
14#include <linux/in.h>
15#include <linux/in6.h>
16#include <linux/slab.h>
17#include <linux/hashtable.h>
18#include <net/sock.h>
19#include <net/af_rxrpc.h>
20#include <net/ip.h>
21#include <net/route.h>
22#include <net/ip6_route.h>
23#include "ar-internal.h"
24
25/*
26 * Hash a peer key.
27 */
28static unsigned long rxrpc_peer_hash_key(struct rxrpc_local *local,
29					 const struct sockaddr_rxrpc *srx)
30{
31	const u16 *p;
32	unsigned int i, size;
33	unsigned long hash_key;
34
35	_enter("");
36
37	hash_key = (unsigned long)local / __alignof__(*local);
38	hash_key += srx->transport_type;
39	hash_key += srx->transport_len;
40	hash_key += srx->transport.family;
41
42	switch (srx->transport.family) {
43	case AF_INET:
44		hash_key += (u16 __force)srx->transport.sin.sin_port;
45		size = sizeof(srx->transport.sin.sin_addr);
46		p = (u16 *)&srx->transport.sin.sin_addr;
47		break;
48#ifdef CONFIG_AF_RXRPC_IPV6
49	case AF_INET6:
50		hash_key += (u16 __force)srx->transport.sin.sin_port;
51		size = sizeof(srx->transport.sin6.sin6_addr);
52		p = (u16 *)&srx->transport.sin6.sin6_addr;
53		break;
54#endif
55	default:
56		WARN(1, "AF_RXRPC: Unsupported transport address family\n");
57		return 0;
58	}
59
60	/* Step through the peer address in 16-bit portions for speed */
61	for (i = 0; i < size; i += sizeof(*p), p++)
62		hash_key += *p;
63
64	_leave(" 0x%lx", hash_key);
65	return hash_key;
66}
67
68/*
69 * Compare a peer to a key.  Return -ve, 0 or +ve to indicate less than, same
70 * or greater than.
71 *
72 * Unfortunately, the primitives in linux/hashtable.h don't allow for sorted
73 * buckets and mid-bucket insertion, so we don't make full use of this
74 * information at this point.
75 */
76static long rxrpc_peer_cmp_key(const struct rxrpc_peer *peer,
77			       struct rxrpc_local *local,
78			       const struct sockaddr_rxrpc *srx,
79			       unsigned long hash_key)
80{
81	long diff;
82
83	diff = ((peer->hash_key - hash_key) ?:
84		((unsigned long)peer->local - (unsigned long)local) ?:
85		(peer->srx.transport_type - srx->transport_type) ?:
86		(peer->srx.transport_len - srx->transport_len) ?:
87		(peer->srx.transport.family - srx->transport.family));
88	if (diff != 0)
89		return diff;
90
91	switch (srx->transport.family) {
92	case AF_INET:
93		return ((u16 __force)peer->srx.transport.sin.sin_port -
94			(u16 __force)srx->transport.sin.sin_port) ?:
95			memcmp(&peer->srx.transport.sin.sin_addr,
96			       &srx->transport.sin.sin_addr,
97			       sizeof(struct in_addr));
98#ifdef CONFIG_AF_RXRPC_IPV6
99	case AF_INET6:
100		return ((u16 __force)peer->srx.transport.sin6.sin6_port -
101			(u16 __force)srx->transport.sin6.sin6_port) ?:
102			memcmp(&peer->srx.transport.sin6.sin6_addr,
103			       &srx->transport.sin6.sin6_addr,
104			       sizeof(struct in6_addr));
105#endif
106	default:
107		BUG();
108	}
109}
110
111/*
112 * Look up a remote transport endpoint for the specified address using RCU.
113 */
114static struct rxrpc_peer *__rxrpc_lookup_peer_rcu(
115	struct rxrpc_local *local,
116	const struct sockaddr_rxrpc *srx,
117	unsigned long hash_key)
118{
119	struct rxrpc_peer *peer;
120	struct rxrpc_net *rxnet = local->rxnet;
121
122	hash_for_each_possible_rcu(rxnet->peer_hash, peer, hash_link, hash_key) {
123		if (rxrpc_peer_cmp_key(peer, local, srx, hash_key) == 0 &&
124		    refcount_read(&peer->ref) > 0)
125			return peer;
126	}
127
128	return NULL;
129}
130
131/*
132 * Look up a remote transport endpoint for the specified address using RCU.
133 */
134struct rxrpc_peer *rxrpc_lookup_peer_rcu(struct rxrpc_local *local,
135					 const struct sockaddr_rxrpc *srx)
136{
137	struct rxrpc_peer *peer;
138	unsigned long hash_key = rxrpc_peer_hash_key(local, srx);
139
140	peer = __rxrpc_lookup_peer_rcu(local, srx, hash_key);
141	if (peer) {
142		_net("PEER %d {%pISp}", peer->debug_id, &peer->srx.transport);
143		_leave(" = %p {u=%d}", peer, refcount_read(&peer->ref));
144	}
145	return peer;
146}
147
148/*
149 * assess the MTU size for the network interface through which this peer is
150 * reached
151 */
152static void rxrpc_assess_MTU_size(struct rxrpc_sock *rx,
153				  struct rxrpc_peer *peer)
154{
155	struct net *net = sock_net(&rx->sk);
156	struct dst_entry *dst;
157	struct rtable *rt;
158	struct flowi fl;
159	struct flowi4 *fl4 = &fl.u.ip4;
160#ifdef CONFIG_AF_RXRPC_IPV6
161	struct flowi6 *fl6 = &fl.u.ip6;
162#endif
163
164	peer->if_mtu = 1500;
165
166	memset(&fl, 0, sizeof(fl));
167	switch (peer->srx.transport.family) {
168	case AF_INET:
169		rt = ip_route_output_ports(
170			net, fl4, NULL,
171			peer->srx.transport.sin.sin_addr.s_addr, 0,
172			htons(7000), htons(7001), IPPROTO_UDP, 0, 0);
173		if (IS_ERR(rt)) {
174			_leave(" [route err %ld]", PTR_ERR(rt));
175			return;
176		}
177		dst = &rt->dst;
178		break;
179
180#ifdef CONFIG_AF_RXRPC_IPV6
181	case AF_INET6:
182		fl6->flowi6_iif = LOOPBACK_IFINDEX;
183		fl6->flowi6_scope = RT_SCOPE_UNIVERSE;
184		fl6->flowi6_proto = IPPROTO_UDP;
185		memcpy(&fl6->daddr, &peer->srx.transport.sin6.sin6_addr,
186		       sizeof(struct in6_addr));
187		fl6->fl6_dport = htons(7001);
188		fl6->fl6_sport = htons(7000);
189		dst = ip6_route_output(net, NULL, fl6);
190		if (dst->error) {
191			_leave(" [route err %d]", dst->error);
192			return;
193		}
194		break;
195#endif
196
197	default:
198		BUG();
199	}
200
201	peer->if_mtu = dst_mtu(dst);
202	dst_release(dst);
203
204	_leave(" [if_mtu %u]", peer->if_mtu);
205}
206
207/*
208 * Allocate a peer.
209 */
210struct rxrpc_peer *rxrpc_alloc_peer(struct rxrpc_local *local, gfp_t gfp)
211{
212	const void *here = __builtin_return_address(0);
213	struct rxrpc_peer *peer;
214
215	_enter("");
216
217	peer = kzalloc(sizeof(struct rxrpc_peer), gfp);
218	if (peer) {
219		refcount_set(&peer->ref, 1);
220		peer->local = rxrpc_get_local(local);
221		INIT_HLIST_HEAD(&peer->error_targets);
222		peer->service_conns = RB_ROOT;
223		seqlock_init(&peer->service_conn_lock);
224		spin_lock_init(&peer->lock);
225		spin_lock_init(&peer->rtt_input_lock);
226		peer->debug_id = atomic_inc_return(&rxrpc_debug_id);
227
228		rxrpc_peer_init_rtt(peer);
229
230		if (RXRPC_TX_SMSS > 2190)
231			peer->cong_cwnd = 2;
232		else if (RXRPC_TX_SMSS > 1095)
233			peer->cong_cwnd = 3;
234		else
235			peer->cong_cwnd = 4;
236		trace_rxrpc_peer(peer->debug_id, rxrpc_peer_new, 1, here);
237	}
238
239	_leave(" = %p", peer);
240	return peer;
241}
242
243/*
244 * Initialise peer record.
245 */
246static void rxrpc_init_peer(struct rxrpc_sock *rx, struct rxrpc_peer *peer,
247			    unsigned long hash_key)
248{
249	peer->hash_key = hash_key;
250	rxrpc_assess_MTU_size(rx, peer);
251	peer->mtu = peer->if_mtu;
252	peer->rtt_last_req = ktime_get_real();
253
254	switch (peer->srx.transport.family) {
255	case AF_INET:
256		peer->hdrsize = sizeof(struct iphdr);
257		break;
258#ifdef CONFIG_AF_RXRPC_IPV6
259	case AF_INET6:
260		peer->hdrsize = sizeof(struct ipv6hdr);
261		break;
262#endif
263	default:
264		BUG();
265	}
266
267	switch (peer->srx.transport_type) {
268	case SOCK_DGRAM:
269		peer->hdrsize += sizeof(struct udphdr);
270		break;
271	default:
272		BUG();
273	}
274
275	peer->hdrsize += sizeof(struct rxrpc_wire_header);
276	peer->maxdata = peer->mtu - peer->hdrsize;
277}
278
279/*
280 * Set up a new peer.
281 */
282static struct rxrpc_peer *rxrpc_create_peer(struct rxrpc_sock *rx,
283					    struct rxrpc_local *local,
284					    struct sockaddr_rxrpc *srx,
285					    unsigned long hash_key,
286					    gfp_t gfp)
287{
288	struct rxrpc_peer *peer;
289
290	_enter("");
291
292	peer = rxrpc_alloc_peer(local, gfp);
293	if (peer) {
294		memcpy(&peer->srx, srx, sizeof(*srx));
295		rxrpc_init_peer(rx, peer, hash_key);
296	}
297
298	_leave(" = %p", peer);
299	return peer;
300}
301
302static void rxrpc_free_peer(struct rxrpc_peer *peer)
303{
304	rxrpc_put_local(peer->local);
305	kfree_rcu(peer, rcu);
306}
307
308/*
309 * Set up a new incoming peer.  There shouldn't be any other matching peers
310 * since we've already done a search in the list from the non-reentrant context
311 * (the data_ready handler) that is the only place we can add new peers.
312 */
313void rxrpc_new_incoming_peer(struct rxrpc_sock *rx, struct rxrpc_local *local,
314			     struct rxrpc_peer *peer)
315{
316	struct rxrpc_net *rxnet = local->rxnet;
317	unsigned long hash_key;
318
319	hash_key = rxrpc_peer_hash_key(local, &peer->srx);
320	rxrpc_init_peer(rx, peer, hash_key);
321
322	spin_lock(&rxnet->peer_hash_lock);
323	hash_add_rcu(rxnet->peer_hash, &peer->hash_link, hash_key);
324	list_add_tail(&peer->keepalive_link, &rxnet->peer_keepalive_new);
325	spin_unlock(&rxnet->peer_hash_lock);
326}
327
328/*
329 * obtain a remote transport endpoint for the specified address
330 */
331struct rxrpc_peer *rxrpc_lookup_peer(struct rxrpc_sock *rx,
332				     struct rxrpc_local *local,
333				     struct sockaddr_rxrpc *srx, gfp_t gfp)
334{
335	struct rxrpc_peer *peer, *candidate;
336	struct rxrpc_net *rxnet = local->rxnet;
337	unsigned long hash_key = rxrpc_peer_hash_key(local, srx);
338
339	_enter("{%pISp}", &srx->transport);
340
341	/* search the peer list first */
342	rcu_read_lock();
343	peer = __rxrpc_lookup_peer_rcu(local, srx, hash_key);
344	if (peer && !rxrpc_get_peer_maybe(peer))
345		peer = NULL;
346	rcu_read_unlock();
347
348	if (!peer) {
349		/* The peer is not yet present in hash - create a candidate
350		 * for a new record and then redo the search.
351		 */
352		candidate = rxrpc_create_peer(rx, local, srx, hash_key, gfp);
353		if (!candidate) {
354			_leave(" = NULL [nomem]");
355			return NULL;
356		}
357
358		spin_lock_bh(&rxnet->peer_hash_lock);
359
360		/* Need to check that we aren't racing with someone else */
361		peer = __rxrpc_lookup_peer_rcu(local, srx, hash_key);
362		if (peer && !rxrpc_get_peer_maybe(peer))
363			peer = NULL;
364		if (!peer) {
365			hash_add_rcu(rxnet->peer_hash,
366				     &candidate->hash_link, hash_key);
367			list_add_tail(&candidate->keepalive_link,
368				      &rxnet->peer_keepalive_new);
369		}
370
371		spin_unlock_bh(&rxnet->peer_hash_lock);
372
373		if (peer)
374			rxrpc_free_peer(candidate);
375		else
376			peer = candidate;
377	}
378
379	_net("PEER %d {%pISp}", peer->debug_id, &peer->srx.transport);
380
381	_leave(" = %p {u=%d}", peer, refcount_read(&peer->ref));
382	return peer;
383}
384
385/*
386 * Get a ref on a peer record.
387 */
388struct rxrpc_peer *rxrpc_get_peer(struct rxrpc_peer *peer)
389{
390	const void *here = __builtin_return_address(0);
391	int r;
392
393	__refcount_inc(&peer->ref, &r);
394	trace_rxrpc_peer(peer->debug_id, rxrpc_peer_got, r + 1, here);
395	return peer;
396}
397
398/*
399 * Get a ref on a peer record unless its usage has already reached 0.
400 */
401struct rxrpc_peer *rxrpc_get_peer_maybe(struct rxrpc_peer *peer)
402{
403	const void *here = __builtin_return_address(0);
404	int r;
405
406	if (peer) {
407		if (__refcount_inc_not_zero(&peer->ref, &r))
408			trace_rxrpc_peer(peer->debug_id, rxrpc_peer_got, r + 1, here);
409		else
410			peer = NULL;
411	}
412	return peer;
413}
414
415/*
416 * Discard a peer record.
417 */
418static void __rxrpc_put_peer(struct rxrpc_peer *peer)
419{
420	struct rxrpc_net *rxnet = peer->local->rxnet;
421
422	ASSERT(hlist_empty(&peer->error_targets));
423
424	spin_lock_bh(&rxnet->peer_hash_lock);
425	hash_del_rcu(&peer->hash_link);
426	list_del_init(&peer->keepalive_link);
427	spin_unlock_bh(&rxnet->peer_hash_lock);
428
429	rxrpc_free_peer(peer);
430}
431
432/*
433 * Drop a ref on a peer record.
434 */
435void rxrpc_put_peer(struct rxrpc_peer *peer)
436{
437	const void *here = __builtin_return_address(0);
438	unsigned int debug_id;
439	bool dead;
440	int r;
441
442	if (peer) {
443		debug_id = peer->debug_id;
444		dead = __refcount_dec_and_test(&peer->ref, &r);
445		trace_rxrpc_peer(debug_id, rxrpc_peer_put, r - 1, here);
446		if (dead)
447			__rxrpc_put_peer(peer);
448	}
449}
450
451/*
452 * Drop a ref on a peer record where the caller already holds the
453 * peer_hash_lock.
454 */
455void rxrpc_put_peer_locked(struct rxrpc_peer *peer)
456{
457	const void *here = __builtin_return_address(0);
458	unsigned int debug_id = peer->debug_id;
459	bool dead;
460	int r;
461
462	dead = __refcount_dec_and_test(&peer->ref, &r);
463	trace_rxrpc_peer(debug_id, rxrpc_peer_put, r - 1, here);
464	if (dead) {
465		hash_del_rcu(&peer->hash_link);
466		list_del_init(&peer->keepalive_link);
467		rxrpc_free_peer(peer);
468	}
469}
470
471/*
472 * Make sure all peer records have been discarded.
473 */
474void rxrpc_destroy_all_peers(struct rxrpc_net *rxnet)
475{
476	struct rxrpc_peer *peer;
477	int i;
478
479	for (i = 0; i < HASH_SIZE(rxnet->peer_hash); i++) {
480		if (hlist_empty(&rxnet->peer_hash[i]))
481			continue;
482
483		hlist_for_each_entry(peer, &rxnet->peer_hash[i], hash_link) {
484			pr_err("Leaked peer %u {%u} %pISp\n",
485			       peer->debug_id,
486			       refcount_read(&peer->ref),
487			       &peer->srx.transport);
488		}
489	}
490}
491
492/**
493 * rxrpc_kernel_get_peer - Get the peer address of a call
494 * @sock: The socket on which the call is in progress.
495 * @call: The call to query
496 * @_srx: Where to place the result
497 *
498 * Get the address of the remote peer in a call.
499 */
500void rxrpc_kernel_get_peer(struct socket *sock, struct rxrpc_call *call,
501			   struct sockaddr_rxrpc *_srx)
502{
503	*_srx = call->peer->srx;
504}
505EXPORT_SYMBOL(rxrpc_kernel_get_peer);
506
507/**
508 * rxrpc_kernel_get_srtt - Get a call's peer smoothed RTT
509 * @sock: The socket on which the call is in progress.
510 * @call: The call to query
511 * @_srtt: Where to store the SRTT value.
512 *
513 * Get the call's peer smoothed RTT in uS.
514 */
515bool rxrpc_kernel_get_srtt(struct socket *sock, struct rxrpc_call *call,
516			   u32 *_srtt)
517{
518	struct rxrpc_peer *peer = call->peer;
519
520	if (peer->rtt_count == 0) {
521		*_srtt = 1000000; /* 1S */
522		return false;
523	}
524
525	*_srtt = call->peer->srtt_us >> 3;
526	return true;
527}
528EXPORT_SYMBOL(rxrpc_kernel_get_srtt);
529