1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
|
// SPDX-License-Identifier: GPL-2.0-or-later
/* Service connection management
*
* Copyright (C) 2016 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#include <linux/slab.h>
#include "ar-internal.h"
static struct rxrpc_bundle rxrpc_service_dummy_bundle = {
.ref = REFCOUNT_INIT(1),
.debug_id = UINT_MAX,
};
/*
* Find a service connection under RCU conditions.
*
* We could use a hash table, but that is subject to bucket stuffing by an
* attacker as the client gets to pick the epoch and cid values and would know
* the hash function. So, instead, we use a hash table for the peer and from
* that an rbtree to find the service connection. Under ordinary circumstances
* it might be slower than a large hash table, but it is at least limited in
* depth.
*/
struct rxrpc_connection *rxrpc_find_service_conn_rcu(struct rxrpc_peer *peer,
struct sk_buff *skb)
{
struct rxrpc_connection *conn = NULL;
struct rxrpc_conn_proto k;
struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
struct rb_node *p;
unsigned int seq = 0;
k.epoch = sp->hdr.epoch;
k.cid = sp->hdr.cid & RXRPC_CIDMASK;
do {
/* Unfortunately, rbtree walking doesn't give reliable results
* under just the RCU read lock, so we have to check for
* changes.
*/
read_seqbegin_or_lock(&peer->service_conn_lock, &seq);
p = rcu_dereference_raw(peer->service_conns.rb_node);
while (p) {
conn = rb_entry(p, struct rxrpc_connection, service_node);
if (conn->proto.index_key < k.index_key)
p = rcu_dereference_raw(p->rb_left);
else if (conn->proto.index_key > k.index_key)
p = rcu_dereference_raw(p->rb_right);
else
break;
conn = NULL;
}
} while (need_seqretry(&peer->service_conn_lock, seq));
done_seqretry(&peer->service_conn_lock, seq);
_leave(" = %d", conn ? conn->debug_id : -1);
return conn;
}
/*
* Insert a service connection into a peer's tree, thereby making it a target
* for incoming packets.
*/
static void rxrpc_publish_service_conn(struct rxrpc_peer *peer,
struct rxrpc_connection *conn)
{
struct rxrpc_connection *cursor = NULL;
struct rxrpc_conn_proto k = conn->proto;
struct rb_node **pp, *parent;
write_seqlock(&peer->service_conn_lock);
pp = &peer->service_conns.rb_node;
parent = NULL;
while (*pp) {
parent = *pp;
cursor = rb_entry(parent,
struct rxrpc_connection, service_node);
if (cursor->proto.index_key < k.index_key)
pp = &(*pp)->rb_left;
else if (cursor->proto.index_key > k.index_key)
pp = &(*pp)->rb_right;
else
goto found_extant_conn;
}
rb_link_node_rcu(&conn->service_node, parent, pp);
rb_insert_color(&conn->service_node, &peer->service_conns);
conn_published:
set_bit(RXRPC_CONN_IN_SERVICE_CONNS, &conn->flags);
write_sequnlock(&peer->service_conn_lock);
_leave(" = %d [new]", conn->debug_id);
return;
found_extant_conn:
if (refcount_read(&cursor->ref) == 0)
goto replace_old_connection;
write_sequnlock(&peer->service_conn_lock);
/* We should not be able to get here. rxrpc_incoming_connection() is
* called in a non-reentrant context, so there can't be a race to
* insert a new connection.
*/
BUG();
replace_old_connection:
/* The old connection is from an outdated epoch. */
_debug("replace conn");
rb_replace_node_rcu(&cursor->service_node,
&conn->service_node,
&peer->service_conns);
clear_bit(RXRPC_CONN_IN_SERVICE_CONNS, &cursor->flags);
goto conn_published;
}
/*
* Preallocate a service connection. The connection is placed on the proc and
* reap lists so that we don't have to get the lock from BH context.
*/
struct rxrpc_connection *rxrpc_prealloc_service_connection(struct rxrpc_net *rxnet,
gfp_t gfp)
{
struct rxrpc_connection *conn = rxrpc_alloc_connection(rxnet, gfp);
if (conn) {
/* We maintain an extra ref on the connection whilst it is on
* the rxrpc_connections list.
*/
conn->state = RXRPC_CONN_SERVICE_PREALLOC;
refcount_set(&conn->ref, 2);
conn->bundle = rxrpc_get_bundle(&rxrpc_service_dummy_bundle,
rxrpc_bundle_get_service_conn);
atomic_inc(&rxnet->nr_conns);
write_lock(&rxnet->conn_lock);
list_add_tail(&conn->link, &rxnet->service_conns);
list_add_tail(&conn->proc_link, &rxnet->conn_proc_list);
write_unlock(&rxnet->conn_lock);
rxrpc_see_connection(conn, rxrpc_conn_new_service);
}
return conn;
}
/*
* Set up an incoming connection. This is called in BH context with the RCU
* read lock held.
*/
void rxrpc_new_incoming_connection(struct rxrpc_sock *rx,
struct rxrpc_connection *conn,
const struct rxrpc_security *sec,
struct sk_buff *skb)
{
struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
_enter("");
conn->proto.epoch = sp->hdr.epoch;
conn->proto.cid = sp->hdr.cid & RXRPC_CIDMASK;
conn->orig_service_id = sp->hdr.serviceId;
conn->service_id = sp->hdr.serviceId;
conn->security_ix = sp->hdr.securityIndex;
conn->out_clientflag = 0;
conn->security = sec;
if (conn->security_ix)
conn->state = RXRPC_CONN_SERVICE_UNSECURED;
else
conn->state = RXRPC_CONN_SERVICE;
/* See if we should upgrade the service. This can only happen on the
* first packet on a new connection. Once done, it applies to all
* subsequent calls on that connection.
*/
if (sp->hdr.userStatus == RXRPC_USERSTATUS_SERVICE_UPGRADE &&
conn->service_id == rx->service_upgrade.from)
conn->service_id = rx->service_upgrade.to;
atomic_set(&conn->active, 1);
/* Make the connection a target for incoming packets. */
rxrpc_publish_service_conn(conn->peer, conn);
}
/*
* Remove the service connection from the peer's tree, thereby removing it as a
* target for incoming packets.
*/
void rxrpc_unpublish_service_conn(struct rxrpc_connection *conn)
{
struct rxrpc_peer *peer = conn->peer;
write_seqlock(&peer->service_conn_lock);
if (test_and_clear_bit(RXRPC_CONN_IN_SERVICE_CONNS, &conn->flags))
rb_erase(&conn->service_node, &peer->service_conns);
write_sequnlock(&peer->service_conn_lock);
}
|
