• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Linux WiMAX
4  * Generic messaging interface between userspace and driver/device
5  *
6  * Copyright (C) 2007-2008 Intel Corporation <linux-wimax@intel.com>
7  * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
8  *
9  * This implements a direct communication channel between user space and
10  * the driver/device, by which free form messages can be sent back and
11  * forth.
12  *
13  * This is intended for device-specific features, vendor quirks, etc.
14  *
15  * See include/net/wimax.h
16  *
17  * GENERIC NETLINK ENCODING AND CAPACITY
18  *
19  * A destination "pipe name" is added to each message; it is up to the
20  * drivers to assign or use those names (if using them at all).
21  *
22  * Messages are encoded as a binary netlink attribute using nla_put()
23  * using type NLA_UNSPEC (as some versions of libnl still in
24  * deployment don't yet understand NLA_BINARY).
25  *
26  * The maximum capacity of this transport is PAGESIZE per message (so
27  * the actual payload will be bit smaller depending on the
28  * netlink/generic netlink attributes and headers).
29  *
30  * RECEPTION OF MESSAGES
31  *
32  * When a message is received from user space, it is passed verbatim
33  * to the driver calling wimax_dev->op_msg_from_user(). The return
34  * value from this function is passed back to user space as an ack
35  * over the generic netlink protocol.
36  *
37  * The stack doesn't do any processing or interpretation of these
38  * messages.
39  *
40  * SENDING MESSAGES
41  *
42  * Messages can be sent with wimax_msg().
43  *
44  * If the message delivery needs to happen on a different context to
45  * that of its creation, wimax_msg_alloc() can be used to get a
46  * pointer to the message that can be delivered later on with
47  * wimax_msg_send().
48  *
49  * ROADMAP
50  *
51  * wimax_gnl_doit_msg_from_user()    Process a message from user space
52  *   wimax_dev_get_by_genl_info()
53  *   wimax_dev->op_msg_from_user()   Delivery of message to the driver
54  *
55  * wimax_msg()                       Send a message to user space
56  *   wimax_msg_alloc()
57  *   wimax_msg_send()
58  */
59 #include <linux/device.h>
60 #include <linux/slab.h>
61 #include <net/genetlink.h>
62 #include <linux/netdevice.h>
63 #include <linux/wimax.h>
64 #include <linux/security.h>
65 #include <linux/export.h>
66 #include "wimax-internal.h"
67 
68 
69 #define D_SUBMODULE op_msg
70 #include "debug-levels.h"
71 
72 
73 /**
74  * wimax_msg_alloc - Create a new skb for sending a message to userspace
75  *
76  * @wimax_dev: WiMAX device descriptor
77  * @pipe_name: "named pipe" the message will be sent to
78  * @msg: pointer to the message data to send
79  * @size: size of the message to send (in bytes), including the header.
80  * @gfp_flags: flags for memory allocation.
81  *
82  * Returns: %0 if ok, negative errno code on error
83  *
84  * Description:
85  *
86  * Allocates an skb that will contain the message to send to user
87  * space over the messaging pipe and initializes it, copying the
88  * payload.
89  *
90  * Once this call is done, you can deliver it with
91  * wimax_msg_send().
92  *
93  * IMPORTANT:
94  *
95  * Don't use skb_push()/skb_pull()/skb_reserve() on the skb, as
96  * wimax_msg_send() depends on skb->data being placed at the
97  * beginning of the user message.
98  *
99  * Unlike other WiMAX stack calls, this call can be used way early,
100  * even before wimax_dev_add() is called, as long as the
101  * wimax_dev->net_dev pointer is set to point to a proper
102  * net_dev. This is so that drivers can use it early in case they need
103  * to send stuff around or communicate with user space.
104  */
wimax_msg_alloc(struct wimax_dev * wimax_dev,const char * pipe_name,const void * msg,size_t size,gfp_t gfp_flags)105 struct sk_buff *wimax_msg_alloc(struct wimax_dev *wimax_dev,
106 				const char *pipe_name,
107 				const void *msg, size_t size,
108 				gfp_t gfp_flags)
109 {
110 	int result;
111 	struct device *dev = wimax_dev_to_dev(wimax_dev);
112 	size_t msg_size;
113 	void *genl_msg;
114 	struct sk_buff *skb;
115 
116 	msg_size = nla_total_size(size)
117 		+ nla_total_size(sizeof(u32))
118 		+ (pipe_name ? nla_total_size(strlen(pipe_name)) : 0);
119 	result = -ENOMEM;
120 	skb = genlmsg_new(msg_size, gfp_flags);
121 	if (skb == NULL)
122 		goto error_new;
123 	genl_msg = genlmsg_put(skb, 0, 0, &wimax_gnl_family,
124 			       0, WIMAX_GNL_OP_MSG_TO_USER);
125 	if (genl_msg == NULL) {
126 		dev_err(dev, "no memory to create generic netlink message\n");
127 		goto error_genlmsg_put;
128 	}
129 	result = nla_put_u32(skb, WIMAX_GNL_MSG_IFIDX,
130 			     wimax_dev->net_dev->ifindex);
131 	if (result < 0) {
132 		dev_err(dev, "no memory to add ifindex attribute\n");
133 		goto error_nla_put;
134 	}
135 	if (pipe_name) {
136 		result = nla_put_string(skb, WIMAX_GNL_MSG_PIPE_NAME,
137 					pipe_name);
138 		if (result < 0) {
139 			dev_err(dev, "no memory to add pipe_name attribute\n");
140 			goto error_nla_put;
141 		}
142 	}
143 	result = nla_put(skb, WIMAX_GNL_MSG_DATA, size, msg);
144 	if (result < 0) {
145 		dev_err(dev, "no memory to add payload (msg %p size %zu) in "
146 			"attribute: %d\n", msg, size, result);
147 		goto error_nla_put;
148 	}
149 	genlmsg_end(skb, genl_msg);
150 	return skb;
151 
152 error_nla_put:
153 error_genlmsg_put:
154 error_new:
155 	nlmsg_free(skb);
156 	return ERR_PTR(result);
157 }
158 EXPORT_SYMBOL_GPL(wimax_msg_alloc);
159 
160 
161 /**
162  * wimax_msg_data_len - Return a pointer and size of a message's payload
163  *
164  * @msg: Pointer to a message created with wimax_msg_alloc()
165  * @size: Pointer to where to store the message's size
166  *
167  * Returns the pointer to the message data.
168  */
wimax_msg_data_len(struct sk_buff * msg,size_t * size)169 const void *wimax_msg_data_len(struct sk_buff *msg, size_t *size)
170 {
171 	struct nlmsghdr *nlh = (void *) msg->head;
172 	struct nlattr *nla;
173 
174 	nla = nlmsg_find_attr(nlh, sizeof(struct genlmsghdr),
175 			      WIMAX_GNL_MSG_DATA);
176 	if (nla == NULL) {
177 		pr_err("Cannot find attribute WIMAX_GNL_MSG_DATA\n");
178 		return NULL;
179 	}
180 	*size = nla_len(nla);
181 	return nla_data(nla);
182 }
183 EXPORT_SYMBOL_GPL(wimax_msg_data_len);
184 
185 
186 /**
187  * wimax_msg_data - Return a pointer to a message's payload
188  *
189  * @msg: Pointer to a message created with wimax_msg_alloc()
190  */
wimax_msg_data(struct sk_buff * msg)191 const void *wimax_msg_data(struct sk_buff *msg)
192 {
193 	struct nlmsghdr *nlh = (void *) msg->head;
194 	struct nlattr *nla;
195 
196 	nla = nlmsg_find_attr(nlh, sizeof(struct genlmsghdr),
197 			      WIMAX_GNL_MSG_DATA);
198 	if (nla == NULL) {
199 		pr_err("Cannot find attribute WIMAX_GNL_MSG_DATA\n");
200 		return NULL;
201 	}
202 	return nla_data(nla);
203 }
204 EXPORT_SYMBOL_GPL(wimax_msg_data);
205 
206 
207 /**
208  * wimax_msg_len - Return a message's payload length
209  *
210  * @msg: Pointer to a message created with wimax_msg_alloc()
211  */
wimax_msg_len(struct sk_buff * msg)212 ssize_t wimax_msg_len(struct sk_buff *msg)
213 {
214 	struct nlmsghdr *nlh = (void *) msg->head;
215 	struct nlattr *nla;
216 
217 	nla = nlmsg_find_attr(nlh, sizeof(struct genlmsghdr),
218 			      WIMAX_GNL_MSG_DATA);
219 	if (nla == NULL) {
220 		pr_err("Cannot find attribute WIMAX_GNL_MSG_DATA\n");
221 		return -EINVAL;
222 	}
223 	return nla_len(nla);
224 }
225 EXPORT_SYMBOL_GPL(wimax_msg_len);
226 
227 
228 /**
229  * wimax_msg_send - Send a pre-allocated message to user space
230  *
231  * @wimax_dev: WiMAX device descriptor
232  *
233  * @skb: &struct sk_buff returned by wimax_msg_alloc(). Note the
234  *     ownership of @skb is transferred to this function.
235  *
236  * Returns: 0 if ok, < 0 errno code on error
237  *
238  * Description:
239  *
240  * Sends a free-form message that was preallocated with
241  * wimax_msg_alloc() and filled up.
242  *
243  * Assumes that once you pass an skb to this function for sending, it
244  * owns it and will release it when done (on success).
245  *
246  * IMPORTANT:
247  *
248  * Don't use skb_push()/skb_pull()/skb_reserve() on the skb, as
249  * wimax_msg_send() depends on skb->data being placed at the
250  * beginning of the user message.
251  *
252  * Unlike other WiMAX stack calls, this call can be used way early,
253  * even before wimax_dev_add() is called, as long as the
254  * wimax_dev->net_dev pointer is set to point to a proper
255  * net_dev. This is so that drivers can use it early in case they need
256  * to send stuff around or communicate with user space.
257  */
wimax_msg_send(struct wimax_dev * wimax_dev,struct sk_buff * skb)258 int wimax_msg_send(struct wimax_dev *wimax_dev, struct sk_buff *skb)
259 {
260 	struct device *dev = wimax_dev_to_dev(wimax_dev);
261 	void *msg = skb->data;
262 	size_t size = skb->len;
263 	might_sleep();
264 
265 	d_printf(1, dev, "CTX: wimax msg, %zu bytes\n", size);
266 	d_dump(2, dev, msg, size);
267 	genlmsg_multicast(&wimax_gnl_family, skb, 0, 0, GFP_KERNEL);
268 	d_printf(1, dev, "CTX: genl multicast done\n");
269 	return 0;
270 }
271 EXPORT_SYMBOL_GPL(wimax_msg_send);
272 
273 
274 /**
275  * wimax_msg - Send a message to user space
276  *
277  * @wimax_dev: WiMAX device descriptor (properly referenced)
278  * @pipe_name: "named pipe" the message will be sent to
279  * @buf: pointer to the message to send.
280  * @size: size of the buffer pointed to by @buf (in bytes).
281  * @gfp_flags: flags for memory allocation.
282  *
283  * Returns: %0 if ok, negative errno code on error.
284  *
285  * Description:
286  *
287  * Sends a free-form message to user space on the device @wimax_dev.
288  *
289  * NOTES:
290  *
291  * Once the @skb is given to this function, who will own it and will
292  * release it when done (unless it returns error).
293  */
wimax_msg(struct wimax_dev * wimax_dev,const char * pipe_name,const void * buf,size_t size,gfp_t gfp_flags)294 int wimax_msg(struct wimax_dev *wimax_dev, const char *pipe_name,
295 	      const void *buf, size_t size, gfp_t gfp_flags)
296 {
297 	int result = -ENOMEM;
298 	struct sk_buff *skb;
299 
300 	skb = wimax_msg_alloc(wimax_dev, pipe_name, buf, size, gfp_flags);
301 	if (IS_ERR(skb))
302 		result = PTR_ERR(skb);
303 	else
304 		result = wimax_msg_send(wimax_dev, skb);
305 	return result;
306 }
307 EXPORT_SYMBOL_GPL(wimax_msg);
308 
309 /*
310  * Relays a message from user space to the driver
311  *
312  * The skb is passed to the driver-specific function with the netlink
313  * and generic netlink headers already stripped.
314  *
315  * This call will block while handling/relaying the message.
316  */
wimax_gnl_doit_msg_from_user(struct sk_buff * skb,struct genl_info * info)317 int wimax_gnl_doit_msg_from_user(struct sk_buff *skb, struct genl_info *info)
318 {
319 	int result, ifindex;
320 	struct wimax_dev *wimax_dev;
321 	struct device *dev;
322 	struct nlmsghdr *nlh = info->nlhdr;
323 	char *pipe_name;
324 	void *msg_buf;
325 	size_t msg_len;
326 
327 	might_sleep();
328 	d_fnstart(3, NULL, "(skb %p info %p)\n", skb, info);
329 	result = -ENODEV;
330 	if (info->attrs[WIMAX_GNL_MSG_IFIDX] == NULL) {
331 		pr_err("WIMAX_GNL_MSG_FROM_USER: can't find IFIDX attribute\n");
332 		goto error_no_wimax_dev;
333 	}
334 	ifindex = nla_get_u32(info->attrs[WIMAX_GNL_MSG_IFIDX]);
335 	wimax_dev = wimax_dev_get_by_genl_info(info, ifindex);
336 	if (wimax_dev == NULL)
337 		goto error_no_wimax_dev;
338 	dev = wimax_dev_to_dev(wimax_dev);
339 
340 	/* Unpack arguments */
341 	result = -EINVAL;
342 	if (info->attrs[WIMAX_GNL_MSG_DATA] == NULL) {
343 		dev_err(dev, "WIMAX_GNL_MSG_FROM_USER: can't find MSG_DATA "
344 			"attribute\n");
345 		goto error_no_data;
346 	}
347 	msg_buf = nla_data(info->attrs[WIMAX_GNL_MSG_DATA]);
348 	msg_len = nla_len(info->attrs[WIMAX_GNL_MSG_DATA]);
349 
350 	if (info->attrs[WIMAX_GNL_MSG_PIPE_NAME] == NULL)
351 		pipe_name = NULL;
352 	else {
353 		struct nlattr *attr = info->attrs[WIMAX_GNL_MSG_PIPE_NAME];
354 		size_t attr_len = nla_len(attr);
355 		/* libnl-1.1 does not yet support NLA_NUL_STRING */
356 		result = -ENOMEM;
357 		pipe_name = kstrndup(nla_data(attr), attr_len + 1, GFP_KERNEL);
358 		if (pipe_name == NULL)
359 			goto error_alloc;
360 		pipe_name[attr_len] = 0;
361 	}
362 	mutex_lock(&wimax_dev->mutex);
363 	result = wimax_dev_is_ready(wimax_dev);
364 	if (result == -ENOMEDIUM)
365 		result = 0;
366 	if (result < 0)
367 		goto error_not_ready;
368 	result = -ENOSYS;
369 	if (wimax_dev->op_msg_from_user == NULL)
370 		goto error_noop;
371 
372 	d_printf(1, dev,
373 		 "CRX: nlmsghdr len %u type %u flags 0x%04x seq 0x%x pid %u\n",
374 		 nlh->nlmsg_len, nlh->nlmsg_type, nlh->nlmsg_flags,
375 		 nlh->nlmsg_seq, nlh->nlmsg_pid);
376 	d_printf(1, dev, "CRX: wimax message %zu bytes\n", msg_len);
377 	d_dump(2, dev, msg_buf, msg_len);
378 
379 	result = wimax_dev->op_msg_from_user(wimax_dev, pipe_name,
380 					     msg_buf, msg_len, info);
381 error_noop:
382 error_not_ready:
383 	mutex_unlock(&wimax_dev->mutex);
384 error_alloc:
385 	kfree(pipe_name);
386 error_no_data:
387 	dev_put(wimax_dev->net_dev);
388 error_no_wimax_dev:
389 	d_fnend(3, NULL, "(skb %p info %p) = %d\n", skb, info, result);
390 	return result;
391 }
392