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