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1a59d1b8 | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
7672d0b5 | 2 | /* |
f3c48ecc | 3 | * connector.c |
1a5645bc | 4 | * |
acb9c1b2 | 5 | * 2004+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net> |
7672d0b5 | 6 | * All rights reserved. |
7672d0b5 EP |
7 | */ |
8 | ||
d2af686c | 9 | #include <linux/compiler.h> |
7672d0b5 EP |
10 | #include <linux/kernel.h> |
11 | #include <linux/module.h> | |
12 | #include <linux/list.h> | |
13 | #include <linux/skbuff.h> | |
9631d79e | 14 | #include <net/netlink.h> |
7672d0b5 EP |
15 | #include <linux/moduleparam.h> |
16 | #include <linux/connector.h> | |
5a0e3ad6 | 17 | #include <linux/slab.h> |
8ed965d6 | 18 | #include <linux/mutex.h> |
a0a61a60 LZ |
19 | #include <linux/proc_fs.h> |
20 | #include <linux/spinlock.h> | |
7672d0b5 EP |
21 | |
22 | #include <net/sock.h> | |
23 | ||
24 | MODULE_LICENSE("GPL"); | |
acb9c1b2 | 25 | MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>"); |
7672d0b5 | 26 | MODULE_DESCRIPTION("Generic userspace <-> kernelspace connector."); |
3700c3c2 | 27 | MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_CONNECTOR); |
7672d0b5 | 28 | |
7672d0b5 EP |
29 | static struct cn_dev cdev; |
30 | ||
78374676 | 31 | static int cn_already_initialized; |
7672d0b5 EP |
32 | |
33 | /* | |
34470e0b DF |
34 | * Sends mult (multiple) cn_msg at a time. |
35 | * | |
7672d0b5 EP |
36 | * msg->seq and msg->ack are used to determine message genealogy. |
37 | * When someone sends message it puts there locally unique sequence | |
38 | * and random acknowledge numbers. Sequence number may be copied into | |
39 | * nlmsghdr->nlmsg_seq too. | |
40 | * | |
41 | * Sequence number is incremented with each message to be sent. | |
42 | * | |
ac8f7330 | 43 | * If we expect a reply to our message then the sequence number in |
7672d0b5 EP |
44 | * received message MUST be the same as in original message, and |
45 | * acknowledge number MUST be the same + 1. | |
46 | * | |
47 | * If we receive a message and its sequence number is not equal to the | |
48 | * one we are expecting then it is a new message. | |
49 | * | |
50 | * If we receive a message and its sequence number is the same as one | |
51 | * we are expecting but it's acknowledgement number is not equal to | |
52 | * the acknowledgement number in the original message + 1, then it is | |
53 | * a new message. | |
54 | * | |
34470e0b DF |
55 | * If msg->len != len, then additional cn_msg messages are expected following |
56 | * the first msg. | |
57 | * | |
ac8f7330 DF |
58 | * The message is sent to, the portid if given, the group if given, both if |
59 | * both, or if both are zero then the group is looked up and sent there. | |
7672d0b5 | 60 | */ |
34470e0b | 61 | int cn_netlink_send_mult(struct cn_msg *msg, u16 len, u32 portid, u32 __group, |
ac8f7330 | 62 | gfp_t gfp_mask) |
7672d0b5 EP |
63 | { |
64 | struct cn_callback_entry *__cbq; | |
65 | unsigned int size; | |
66 | struct sk_buff *skb; | |
67 | struct nlmsghdr *nlh; | |
68 | struct cn_msg *data; | |
69 | struct cn_dev *dev = &cdev; | |
70 | u32 group = 0; | |
71 | int found = 0; | |
72 | ||
ac8f7330 DF |
73 | if (portid || __group) { |
74 | group = __group; | |
75 | } else { | |
7672d0b5 EP |
76 | spin_lock_bh(&dev->cbdev->queue_lock); |
77 | list_for_each_entry(__cbq, &dev->cbdev->queue_list, | |
78 | callback_entry) { | |
acd042bb | 79 | if (cn_cb_equal(&__cbq->id.id, &msg->id)) { |
7672d0b5 EP |
80 | found = 1; |
81 | group = __cbq->group; | |
fd00eecc | 82 | break; |
7672d0b5 EP |
83 | } |
84 | } | |
85 | spin_unlock_bh(&dev->cbdev->queue_lock); | |
86 | ||
87 | if (!found) | |
88 | return -ENODEV; | |
7672d0b5 EP |
89 | } |
90 | ||
ac8f7330 | 91 | if (!portid && !netlink_has_listeners(dev->nls, group)) |
b191ba0d EP |
92 | return -ESRCH; |
93 | ||
34470e0b | 94 | size = sizeof(*msg) + len; |
7672d0b5 | 95 | |
9631d79e | 96 | skb = nlmsg_new(size, gfp_mask); |
7672d0b5 EP |
97 | if (!skb) |
98 | return -ENOMEM; | |
99 | ||
9631d79e | 100 | nlh = nlmsg_put(skb, 0, msg->seq, NLMSG_DONE, size, 0); |
85c93166 JMC |
101 | if (!nlh) { |
102 | kfree_skb(skb); | |
103 | return -EMSGSIZE; | |
104 | } | |
7672d0b5 | 105 | |
85c93166 | 106 | data = nlmsg_data(nlh); |
7672d0b5 | 107 | |
ac73bf50 | 108 | memcpy(data, msg, size); |
7672d0b5 EP |
109 | |
110 | NETLINK_CB(skb).dst_group = group; | |
111 | ||
ac8f7330 DF |
112 | if (group) |
113 | return netlink_broadcast(dev->nls, skb, portid, group, | |
114 | gfp_mask); | |
d0164adc MG |
115 | return netlink_unicast(dev->nls, skb, portid, |
116 | !gfpflags_allow_blocking(gfp_mask)); | |
7672d0b5 | 117 | } |
34470e0b DF |
118 | EXPORT_SYMBOL_GPL(cn_netlink_send_mult); |
119 | ||
120 | /* same as cn_netlink_send_mult except msg->len is used for len */ | |
121 | int cn_netlink_send(struct cn_msg *msg, u32 portid, u32 __group, | |
122 | gfp_t gfp_mask) | |
123 | { | |
124 | return cn_netlink_send_mult(msg, msg->len, portid, __group, gfp_mask); | |
125 | } | |
deb0e9b2 | 126 | EXPORT_SYMBOL_GPL(cn_netlink_send); |
7672d0b5 EP |
127 | |
128 | /* | |
129 | * Callback helper - queues work and setup destructor for given data. | |
130 | */ | |
f1489cfb | 131 | static int cn_call_callback(struct sk_buff *skb) |
7672d0b5 | 132 | { |
a30cfa47 | 133 | struct nlmsghdr *nlh; |
04f482fa | 134 | struct cn_callback_entry *i, *cbq = NULL; |
7672d0b5 | 135 | struct cn_dev *dev = &cdev; |
9631d79e | 136 | struct cn_msg *msg = nlmsg_data(nlmsg_hdr(skb)); |
04f482fa | 137 | struct netlink_skb_parms *nsp = &NETLINK_CB(skb); |
acd042bb | 138 | int err = -ENODEV; |
7672d0b5 | 139 | |
a30cfa47 DF |
140 | /* verify msg->len is within skb */ |
141 | nlh = nlmsg_hdr(skb); | |
142 | if (nlh->nlmsg_len < NLMSG_HDRLEN + sizeof(struct cn_msg) + msg->len) | |
143 | return -EINVAL; | |
144 | ||
7672d0b5 | 145 | spin_lock_bh(&dev->cbdev->queue_lock); |
04f482fa PM |
146 | list_for_each_entry(i, &dev->cbdev->queue_list, callback_entry) { |
147 | if (cn_cb_equal(&i->id.id, &msg->id)) { | |
e65f7ee3 | 148 | refcount_inc(&i->refcnt); |
04f482fa | 149 | cbq = i; |
7672d0b5 EP |
150 | break; |
151 | } | |
152 | } | |
153 | spin_unlock_bh(&dev->cbdev->queue_lock); | |
154 | ||
04f482fa PM |
155 | if (cbq != NULL) { |
156 | cbq->callback(msg, nsp); | |
157 | kfree_skb(skb); | |
158 | cn_queue_release_callback(cbq); | |
0e087858 | 159 | err = 0; |
04f482fa PM |
160 | } |
161 | ||
acd042bb | 162 | return err; |
7672d0b5 EP |
163 | } |
164 | ||
7672d0b5 EP |
165 | /* |
166 | * Main netlink receiving function. | |
167 | * | |
00f5e06c | 168 | * It checks skb, netlink header and msg sizes, and calls callback helper. |
7672d0b5 | 169 | */ |
55285bf0 | 170 | static void cn_rx_skb(struct sk_buff *skb) |
7672d0b5 EP |
171 | { |
172 | struct nlmsghdr *nlh; | |
162b2bed | 173 | int len, err; |
7672d0b5 | 174 | |
9631d79e | 175 | if (skb->len >= NLMSG_HDRLEN) { |
b529ccf2 | 176 | nlh = nlmsg_hdr(skb); |
162b2bed | 177 | len = nlmsg_len(nlh); |
7672d0b5 | 178 | |
162b2bed | 179 | if (len < (int)sizeof(struct cn_msg) || |
7672d0b5 | 180 | skb->len < nlh->nlmsg_len || |
55285bf0 | 181 | len > CONNECTOR_MAX_MSG_SIZE) |
6cf92e98 | 182 | return; |
7672d0b5 | 183 | |
55285bf0 | 184 | err = cn_call_callback(skb_get(skb)); |
7672d0b5 EP |
185 | if (err < 0) |
186 | kfree_skb(skb); | |
187 | } | |
7672d0b5 EP |
188 | } |
189 | ||
7672d0b5 EP |
190 | /* |
191 | * Callback add routing - adds callback with given ID and name. | |
192 | * If there is registered callback with the same ID it will not be added. | |
193 | * | |
194 | * May sleep. | |
195 | */ | |
c18e6869 | 196 | int cn_add_callback(const struct cb_id *id, const char *name, |
f3c48ecc VI |
197 | void (*callback)(struct cn_msg *, |
198 | struct netlink_skb_parms *)) | |
7672d0b5 | 199 | { |
7672d0b5 | 200 | struct cn_dev *dev = &cdev; |
7672d0b5 | 201 | |
d6cc7f1a EP |
202 | if (!cn_already_initialized) |
203 | return -EAGAIN; | |
204 | ||
fe6bc89a | 205 | return cn_queue_add_callback(dev->cbdev, name, id, callback); |
7672d0b5 | 206 | } |
deb0e9b2 | 207 | EXPORT_SYMBOL_GPL(cn_add_callback); |
7672d0b5 EP |
208 | |
209 | /* | |
210 | * Callback remove routing - removes callback | |
211 | * with given ID. | |
212 | * If there is no registered callback with given | |
213 | * ID nothing happens. | |
214 | * | |
215 | * May sleep while waiting for reference counter to become zero. | |
216 | */ | |
c18e6869 | 217 | void cn_del_callback(const struct cb_id *id) |
7672d0b5 EP |
218 | { |
219 | struct cn_dev *dev = &cdev; | |
220 | ||
221 | cn_queue_del_callback(dev->cbdev, id); | |
7672d0b5 | 222 | } |
deb0e9b2 | 223 | EXPORT_SYMBOL_GPL(cn_del_callback); |
7672d0b5 | 224 | |
d2af686c | 225 | static int __maybe_unused cn_proc_show(struct seq_file *m, void *v) |
a0a61a60 LZ |
226 | { |
227 | struct cn_queue_dev *dev = cdev.cbdev; | |
228 | struct cn_callback_entry *cbq; | |
229 | ||
230 | seq_printf(m, "Name ID\n"); | |
231 | ||
232 | spin_lock_bh(&dev->queue_lock); | |
233 | ||
234 | list_for_each_entry(cbq, &dev->queue_list, callback_entry) { | |
235 | seq_printf(m, "%-15s %u:%u\n", | |
236 | cbq->id.name, | |
237 | cbq->id.id.idx, | |
238 | cbq->id.id.val); | |
239 | } | |
240 | ||
241 | spin_unlock_bh(&dev->queue_lock); | |
242 | ||
243 | return 0; | |
244 | } | |
245 | ||
0fe763c5 | 246 | static int cn_init(void) |
7672d0b5 EP |
247 | { |
248 | struct cn_dev *dev = &cdev; | |
a31f2d17 PNA |
249 | struct netlink_kernel_cfg cfg = { |
250 | .groups = CN_NETLINK_USERS + 0xf, | |
903e9d1b | 251 | .input = cn_rx_skb, |
a31f2d17 | 252 | }; |
7672d0b5 | 253 | |
9f00d977 | 254 | dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR, &cfg); |
7672d0b5 EP |
255 | if (!dev->nls) |
256 | return -EIO; | |
257 | ||
258 | dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls); | |
259 | if (!dev->cbdev) { | |
b7c6ba6e | 260 | netlink_kernel_release(dev->nls); |
7672d0b5 EP |
261 | return -EINVAL; |
262 | } | |
1a5645bc | 263 | |
d6cc7f1a | 264 | cn_already_initialized = 1; |
7672d0b5 | 265 | |
3f3942ac | 266 | proc_create_single("connector", S_IRUGO, init_net.proc_net, cn_proc_show); |
a0a61a60 | 267 | |
7672d0b5 EP |
268 | return 0; |
269 | } | |
270 | ||
0fe763c5 | 271 | static void cn_fini(void) |
7672d0b5 EP |
272 | { |
273 | struct cn_dev *dev = &cdev; | |
274 | ||
275 | cn_already_initialized = 0; | |
276 | ||
ece31ffd | 277 | remove_proc_entry("connector", init_net.proc_net); |
a0a61a60 | 278 | |
7672d0b5 | 279 | cn_queue_free_dev(dev->cbdev); |
b7c6ba6e | 280 | netlink_kernel_release(dev->nls); |
7672d0b5 EP |
281 | } |
282 | ||
d6cc7f1a | 283 | subsys_initcall(cn_init); |
7672d0b5 | 284 | module_exit(cn_fini); |