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