1 /*
2 * Linux WiMAX
3 * Generic messaging interface between userspace and driver/device
4 *
5 *
6 * Copyright (C) 2007-2008 Intel Corporation <linux-wimax@intel.com>
7 * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License version
11 * 2 as published by the Free Software Foundation.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
21 * 02110-1301, USA.
22 *
23 *
24 * This implements a direct communication channel between user space and
25 * the driver/device, by which free form messages can be sent back and
26 * forth.
27 *
28 * This is intended for device-specific features, vendor quirks, etc.
29 *
30 * See include/net/wimax.h
31 *
32 * GENERIC NETLINK ENCODING AND CAPACITY
33 *
34 * A destination "pipe name" is added to each message; it is up to the
35 * drivers to assign or use those names (if using them at all).
36 *
37 * Messages are encoded as a binary netlink attribute using nla_put()
38 * using type NLA_UNSPEC (as some versions of libnl still in
39 * deployment don't yet understand NLA_BINARY).
40 *
41 * The maximum capacity of this transport is PAGESIZE per message (so
42 * the actual payload will be bit smaller depending on the
43 * netlink/generic netlink attributes and headers).
44 *
45 * RECEPTION OF MESSAGES
46 *
47 * When a message is received from user space, it is passed verbatim
48 * to the driver calling wimax_dev->op_msg_from_user(). The return
49 * value from this function is passed back to user space as an ack
50 * over the generic netlink protocol.
51 *
52 * The stack doesn't do any processing or interpretation of these
53 * messages.
54 *
55 * SENDING MESSAGES
56 *
57 * Messages can be sent with wimax_msg().
58 *
59 * If the message delivery needs to happen on a different context to
60 * that of its creation, wimax_msg_alloc() can be used to get a
61 * pointer to the message that can be delivered later on with
62 * wimax_msg_send().
63 *
64 * ROADMAP
65 *
66 * wimax_gnl_doit_msg_from_user() Process a message from user space
67 * wimax_dev_get_by_genl_info()
68 * wimax_dev->op_msg_from_user() Delivery of message to the driver
69 *
70 * wimax_msg() Send a message to user space
71 * wimax_msg_alloc()
72 * wimax_msg_send()
73 */
74 #include <linux/device.h>
75 #include <linux/slab.h>
76 #include <net/genetlink.h>
77 #include <linux/netdevice.h>
78 #include <linux/wimax.h>
79 #include <linux/security.h>
80 #include <linux/export.h>
81 #include "wimax-internal.h"
82
83
84 #define D_SUBMODULE op_msg
85 #include "debug-levels.h"
86
87
88 /**
89 * wimax_msg_alloc - Create a new skb for sending a message to userspace
90 *
91 * @wimax_dev: WiMAX device descriptor
92 * @pipe_name: "named pipe" the message will be sent to
93 * @msg: pointer to the message data to send
94 * @size: size of the message to send (in bytes), including the header.
95 * @gfp_flags: flags for memory allocation.
96 *
97 * Returns: %0 if ok, negative errno code on error
98 *
99 * Description:
100 *
101 * Allocates an skb that will contain the message to send to user
102 * space over the messaging pipe and initializes it, copying the
103 * payload.
104 *
105 * Once this call is done, you can deliver it with
106 * wimax_msg_send().
107 *
108 * IMPORTANT:
109 *
110 * Don't use skb_push()/skb_pull()/skb_reserve() on the skb, as
111 * wimax_msg_send() depends on skb->data being placed at the
112 * beginning of the user message.
113 *
114 * Unlike other WiMAX stack calls, this call can be used way early,
115 * even before wimax_dev_add() is called, as long as the
116 * wimax_dev->net_dev pointer is set to point to a proper
117 * net_dev. This is so that drivers can use it early in case they need
118 * to send stuff around or communicate with user space.
119 */
wimax_msg_alloc(struct wimax_dev * wimax_dev,const char * pipe_name,const void * msg,size_t size,gfp_t gfp_flags)120 struct sk_buff *wimax_msg_alloc(struct wimax_dev *wimax_dev,
121 const char *pipe_name,
122 const void *msg, size_t size,
123 gfp_t gfp_flags)
124 {
125 int result;
126 struct device *dev = wimax_dev_to_dev(wimax_dev);
127 size_t msg_size;
128 void *genl_msg;
129 struct sk_buff *skb;
130
131 msg_size = nla_total_size(size)
132 + nla_total_size(sizeof(u32))
133 + (pipe_name ? nla_total_size(strlen(pipe_name)) : 0);
134 result = -ENOMEM;
135 skb = genlmsg_new(msg_size, gfp_flags);
136 if (skb == NULL)
137 goto error_new;
138 genl_msg = genlmsg_put(skb, 0, 0, &wimax_gnl_family,
139 0, WIMAX_GNL_OP_MSG_TO_USER);
140 if (genl_msg == NULL) {
141 dev_err(dev, "no memory to create generic netlink message\n");
142 goto error_genlmsg_put;
143 }
144 result = nla_put_u32(skb, WIMAX_GNL_MSG_IFIDX,
145 wimax_dev->net_dev->ifindex);
146 if (result < 0) {
147 dev_err(dev, "no memory to add ifindex attribute\n");
148 goto error_nla_put;
149 }
150 if (pipe_name) {
151 result = nla_put_string(skb, WIMAX_GNL_MSG_PIPE_NAME,
152 pipe_name);
153 if (result < 0) {
154 dev_err(dev, "no memory to add pipe_name attribute\n");
155 goto error_nla_put;
156 }
157 }
158 result = nla_put(skb, WIMAX_GNL_MSG_DATA, size, msg);
159 if (result < 0) {
160 dev_err(dev, "no memory to add payload (msg %p size %zu) in "
161 "attribute: %d\n", msg, size, result);
162 goto error_nla_put;
163 }
164 genlmsg_end(skb, genl_msg);
165 return skb;
166
167 error_nla_put:
168 error_genlmsg_put:
169 error_new:
170 nlmsg_free(skb);
171 return ERR_PTR(result);
172 }
173 EXPORT_SYMBOL_GPL(wimax_msg_alloc);
174
175
176 /**
177 * wimax_msg_data_len - Return a pointer and size of a message's payload
178 *
179 * @msg: Pointer to a message created with wimax_msg_alloc()
180 * @size: Pointer to where to store the message's size
181 *
182 * Returns the pointer to the message data.
183 */
wimax_msg_data_len(struct sk_buff * msg,size_t * size)184 const void *wimax_msg_data_len(struct sk_buff *msg, size_t *size)
185 {
186 struct nlmsghdr *nlh = (void *) msg->head;
187 struct nlattr *nla;
188
189 nla = nlmsg_find_attr(nlh, sizeof(struct genlmsghdr),
190 WIMAX_GNL_MSG_DATA);
191 if (nla == NULL) {
192 pr_err("Cannot find attribute WIMAX_GNL_MSG_DATA\n");
193 return NULL;
194 }
195 *size = nla_len(nla);
196 return nla_data(nla);
197 }
198 EXPORT_SYMBOL_GPL(wimax_msg_data_len);
199
200
201 /**
202 * wimax_msg_data - Return a pointer to a message's payload
203 *
204 * @msg: Pointer to a message created with wimax_msg_alloc()
205 */
wimax_msg_data(struct sk_buff * msg)206 const void *wimax_msg_data(struct sk_buff *msg)
207 {
208 struct nlmsghdr *nlh = (void *) msg->head;
209 struct nlattr *nla;
210
211 nla = nlmsg_find_attr(nlh, sizeof(struct genlmsghdr),
212 WIMAX_GNL_MSG_DATA);
213 if (nla == NULL) {
214 pr_err("Cannot find attribute WIMAX_GNL_MSG_DATA\n");
215 return NULL;
216 }
217 return nla_data(nla);
218 }
219 EXPORT_SYMBOL_GPL(wimax_msg_data);
220
221
222 /**
223 * wimax_msg_len - Return a message's payload length
224 *
225 * @msg: Pointer to a message created with wimax_msg_alloc()
226 */
wimax_msg_len(struct sk_buff * msg)227 ssize_t wimax_msg_len(struct sk_buff *msg)
228 {
229 struct nlmsghdr *nlh = (void *) msg->head;
230 struct nlattr *nla;
231
232 nla = nlmsg_find_attr(nlh, sizeof(struct genlmsghdr),
233 WIMAX_GNL_MSG_DATA);
234 if (nla == NULL) {
235 pr_err("Cannot find attribute WIMAX_GNL_MSG_DATA\n");
236 return -EINVAL;
237 }
238 return nla_len(nla);
239 }
240 EXPORT_SYMBOL_GPL(wimax_msg_len);
241
242
243 /**
244 * wimax_msg_send - Send a pre-allocated message to user space
245 *
246 * @wimax_dev: WiMAX device descriptor
247 *
248 * @skb: &struct sk_buff returned by wimax_msg_alloc(). Note the
249 * ownership of @skb is transferred to this function.
250 *
251 * Returns: 0 if ok, < 0 errno code on error
252 *
253 * Description:
254 *
255 * Sends a free-form message that was preallocated with
256 * wimax_msg_alloc() and filled up.
257 *
258 * Assumes that once you pass an skb to this function for sending, it
259 * owns it and will release it when done (on success).
260 *
261 * IMPORTANT:
262 *
263 * Don't use skb_push()/skb_pull()/skb_reserve() on the skb, as
264 * wimax_msg_send() depends on skb->data being placed at the
265 * beginning of the user message.
266 *
267 * Unlike other WiMAX stack calls, this call can be used way early,
268 * even before wimax_dev_add() is called, as long as the
269 * wimax_dev->net_dev pointer is set to point to a proper
270 * net_dev. This is so that drivers can use it early in case they need
271 * to send stuff around or communicate with user space.
272 */
wimax_msg_send(struct wimax_dev * wimax_dev,struct sk_buff * skb)273 int wimax_msg_send(struct wimax_dev *wimax_dev, struct sk_buff *skb)
274 {
275 struct device *dev = wimax_dev_to_dev(wimax_dev);
276 void *msg = skb->data;
277 size_t size = skb->len;
278 might_sleep();
279
280 d_printf(1, dev, "CTX: wimax msg, %zu bytes\n", size);
281 d_dump(2, dev, msg, size);
282 genlmsg_multicast(&wimax_gnl_family, skb, 0, 0, GFP_KERNEL);
283 d_printf(1, dev, "CTX: genl multicast done\n");
284 return 0;
285 }
286 EXPORT_SYMBOL_GPL(wimax_msg_send);
287
288
289 /**
290 * wimax_msg - Send a message to user space
291 *
292 * @wimax_dev: WiMAX device descriptor (properly referenced)
293 * @pipe_name: "named pipe" the message will be sent to
294 * @buf: pointer to the message to send.
295 * @size: size of the buffer pointed to by @buf (in bytes).
296 * @gfp_flags: flags for memory allocation.
297 *
298 * Returns: %0 if ok, negative errno code on error.
299 *
300 * Description:
301 *
302 * Sends a free-form message to user space on the device @wimax_dev.
303 *
304 * NOTES:
305 *
306 * Once the @skb is given to this function, who will own it and will
307 * release it when done (unless it returns error).
308 */
wimax_msg(struct wimax_dev * wimax_dev,const char * pipe_name,const void * buf,size_t size,gfp_t gfp_flags)309 int wimax_msg(struct wimax_dev *wimax_dev, const char *pipe_name,
310 const void *buf, size_t size, gfp_t gfp_flags)
311 {
312 int result = -ENOMEM;
313 struct sk_buff *skb;
314
315 skb = wimax_msg_alloc(wimax_dev, pipe_name, buf, size, gfp_flags);
316 if (IS_ERR(skb))
317 result = PTR_ERR(skb);
318 else
319 result = wimax_msg_send(wimax_dev, skb);
320 return result;
321 }
322 EXPORT_SYMBOL_GPL(wimax_msg);
323
324 /*
325 * Relays a message from user space to the driver
326 *
327 * The skb is passed to the driver-specific function with the netlink
328 * and generic netlink headers already stripped.
329 *
330 * This call will block while handling/relaying the message.
331 */
wimax_gnl_doit_msg_from_user(struct sk_buff * skb,struct genl_info * info)332 int wimax_gnl_doit_msg_from_user(struct sk_buff *skb, struct genl_info *info)
333 {
334 int result, ifindex;
335 struct wimax_dev *wimax_dev;
336 struct device *dev;
337 struct nlmsghdr *nlh = info->nlhdr;
338 char *pipe_name;
339 void *msg_buf;
340 size_t msg_len;
341
342 might_sleep();
343 d_fnstart(3, NULL, "(skb %p info %p)\n", skb, info);
344 result = -ENODEV;
345 if (info->attrs[WIMAX_GNL_MSG_IFIDX] == NULL) {
346 pr_err("WIMAX_GNL_MSG_FROM_USER: can't find IFIDX attribute\n");
347 goto error_no_wimax_dev;
348 }
349 ifindex = nla_get_u32(info->attrs[WIMAX_GNL_MSG_IFIDX]);
350 wimax_dev = wimax_dev_get_by_genl_info(info, ifindex);
351 if (wimax_dev == NULL)
352 goto error_no_wimax_dev;
353 dev = wimax_dev_to_dev(wimax_dev);
354
355 /* Unpack arguments */
356 result = -EINVAL;
357 if (info->attrs[WIMAX_GNL_MSG_DATA] == NULL) {
358 dev_err(dev, "WIMAX_GNL_MSG_FROM_USER: can't find MSG_DATA "
359 "attribute\n");
360 goto error_no_data;
361 }
362 msg_buf = nla_data(info->attrs[WIMAX_GNL_MSG_DATA]);
363 msg_len = nla_len(info->attrs[WIMAX_GNL_MSG_DATA]);
364
365 if (info->attrs[WIMAX_GNL_MSG_PIPE_NAME] == NULL)
366 pipe_name = NULL;
367 else {
368 struct nlattr *attr = info->attrs[WIMAX_GNL_MSG_PIPE_NAME];
369 size_t attr_len = nla_len(attr);
370 /* libnl-1.1 does not yet support NLA_NUL_STRING */
371 result = -ENOMEM;
372 pipe_name = kstrndup(nla_data(attr), attr_len + 1, GFP_KERNEL);
373 if (pipe_name == NULL)
374 goto error_alloc;
375 pipe_name[attr_len] = 0;
376 }
377 mutex_lock(&wimax_dev->mutex);
378 result = wimax_dev_is_ready(wimax_dev);
379 if (result == -ENOMEDIUM)
380 result = 0;
381 if (result < 0)
382 goto error_not_ready;
383 result = -ENOSYS;
384 if (wimax_dev->op_msg_from_user == NULL)
385 goto error_noop;
386
387 d_printf(1, dev,
388 "CRX: nlmsghdr len %u type %u flags 0x%04x seq 0x%x pid %u\n",
389 nlh->nlmsg_len, nlh->nlmsg_type, nlh->nlmsg_flags,
390 nlh->nlmsg_seq, nlh->nlmsg_pid);
391 d_printf(1, dev, "CRX: wimax message %zu bytes\n", msg_len);
392 d_dump(2, dev, msg_buf, msg_len);
393
394 result = wimax_dev->op_msg_from_user(wimax_dev, pipe_name,
395 msg_buf, msg_len, info);
396 error_noop:
397 error_not_ready:
398 mutex_unlock(&wimax_dev->mutex);
399 error_alloc:
400 kfree(pipe_name);
401 error_no_data:
402 dev_put(wimax_dev->net_dev);
403 error_no_wimax_dev:
404 d_fnend(3, NULL, "(skb %p info %p) = %d\n", skb, info, result);
405 return result;
406 }
407
408