op-msg.c 12.2 KB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432
/*
 * Linux WiMAX
 * Generic messaging interface between userspace and driver/device
 *
 *
 * Copyright (C) 2007-2008 Intel Corporation <linux-wimax@intel.com>
 * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version
 * 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 *
 *
 * This implements a direct communication channel between user space and
 * the driver/device, by which free form messages can be sent back and
 * forth.
 *
 * This is intended for device-specific features, vendor quirks, etc.
 *
 * See include/net/wimax.h
 *
 * GENERIC NETLINK ENCODING AND CAPACITY
 *
 * A destination "pipe name" is added to each message; it is up to the
 * drivers to assign or use those names (if using them at all).
 *
 * Messages are encoded as a binary netlink attribute using nla_put()
 * using type NLA_UNSPEC (as some versions of libnl still in
 * deployment don't yet understand NLA_BINARY).
 *
 * The maximum capacity of this transport is PAGESIZE per message (so
 * the actual payload will be bit smaller depending on the
 * netlink/generic netlink attributes and headers).
 *
 * RECEPTION OF MESSAGES
 *
 * When a message is received from user space, it is passed verbatim
 * to the driver calling wimax_dev->op_msg_from_user(). The return
 * value from this function is passed back to user space as an ack
 * over the generic netlink protocol.
 *
 * The stack doesn't do any processing or interpretation of these
 * messages.
 *
 * SENDING MESSAGES
 *
 * Messages can be sent with wimax_msg().
 *
 * If the message delivery needs to happen on a different context to
 * that of its creation, wimax_msg_alloc() can be used to get a
 * pointer to the message that can be delivered later on with
 * wimax_msg_send().
 *
 * ROADMAP
 *
 * wimax_gnl_doit_msg_from_user()    Process a message from user space
 *   wimax_dev_get_by_genl_info()
 *   wimax_dev->op_msg_from_user()   Delivery of message to the driver
 *
 * wimax_msg()                       Send a message to user space
 *   wimax_msg_alloc()
 *   wimax_msg_send()
 */
#include <linux/device.h>
#include <linux/slab.h>
#include <net/genetlink.h>
#include <linux/netdevice.h>
#include <linux/wimax.h>
#include <linux/security.h>
#include "wimax-internal.h"


#define D_SUBMODULE op_msg
#include "debug-levels.h"


/**
 * wimax_msg_alloc - Create a new skb for sending a message to userspace
 *
 * @wimax_dev: WiMAX device descriptor
 * @pipe_name: "named pipe" the message will be sent to
 * @msg: pointer to the message data to send
 * @size: size of the message to send (in bytes), including the header.
 * @gfp_flags: flags for memory allocation.
 *
 * Returns: %0 if ok, negative errno code on error
 *
 * Description:
 *
 * Allocates an skb that will contain the message to send to user
 * space over the messaging pipe and initializes it, copying the
 * payload.
 *
 * Once this call is done, you can deliver it with
 * wimax_msg_send().
 *
 * IMPORTANT:
 *
 * Don't use skb_push()/skb_pull()/skb_reserve() on the skb, as
 * wimax_msg_send() depends on skb->data being placed at the
 * beginning of the user message.
 *
 * Unlike other WiMAX stack calls, this call can be used way early,
 * even before wimax_dev_add() is called, as long as the
 * wimax_dev->net_dev pointer is set to point to a proper
 * net_dev. This is so that drivers can use it early in case they need
 * to send stuff around or communicate with user space.
 */
struct sk_buff *wimax_msg_alloc(struct wimax_dev *wimax_dev,
				const char *pipe_name,
				const void *msg, size_t size,
				gfp_t gfp_flags)
{
	int result;
	struct device *dev = wimax_dev_to_dev(wimax_dev);
	size_t msg_size;
	void *genl_msg;
	struct sk_buff *skb;

	msg_size = nla_total_size(size)
		+ nla_total_size(sizeof(u32))
		+ (pipe_name ? nla_total_size(strlen(pipe_name)) : 0);
	result = -ENOMEM;
	skb = genlmsg_new(msg_size, gfp_flags);
	if (skb == NULL)
		goto error_new;
	genl_msg = genlmsg_put(skb, 0, 0, &wimax_gnl_family,
			       0, WIMAX_GNL_OP_MSG_TO_USER);
	if (genl_msg == NULL) {
		dev_err(dev, "no memory to create generic netlink message\n");
		goto error_genlmsg_put;
	}
	result = nla_put_u32(skb, WIMAX_GNL_MSG_IFIDX,
			     wimax_dev->net_dev->ifindex);
	if (result < 0) {
		dev_err(dev, "no memory to add ifindex attribute\n");
		goto error_nla_put;
	}
	if (pipe_name) {
		result = nla_put_string(skb, WIMAX_GNL_MSG_PIPE_NAME,
					pipe_name);
		if (result < 0) {
			dev_err(dev, "no memory to add pipe_name attribute\n");
			goto error_nla_put;
		}
	}
	result = nla_put(skb, WIMAX_GNL_MSG_DATA, size, msg);
	if (result < 0) {
		dev_err(dev, "no memory to add payload (msg %p size %zu) in "
			"attribute: %d\n", msg, size, result);
		goto error_nla_put;
	}
	genlmsg_end(skb, genl_msg);
	return skb;

error_nla_put:
error_genlmsg_put:
error_new:
	nlmsg_free(skb);
	return ERR_PTR(result);
}
EXPORT_SYMBOL_GPL(wimax_msg_alloc);


/**
 * wimax_msg_data_len - Return a pointer and size of a message's payload
 *
 * @msg: Pointer to a message created with wimax_msg_alloc()
 * @size: Pointer to where to store the message's size
 *
 * Returns the pointer to the message data.
 */
const void *wimax_msg_data_len(struct sk_buff *msg, size_t *size)
{
	struct nlmsghdr *nlh = (void *) msg->head;
	struct nlattr *nla;

	nla = nlmsg_find_attr(nlh, sizeof(struct genlmsghdr),
			      WIMAX_GNL_MSG_DATA);
	if (nla == NULL) {
		printk(KERN_ERR "Cannot find attribute WIMAX_GNL_MSG_DATA\n");
		return NULL;
	}
	*size = nla_len(nla);
	return nla_data(nla);
}
EXPORT_SYMBOL_GPL(wimax_msg_data_len);


/**
 * wimax_msg_data - Return a pointer to a message's payload
 *
 * @msg: Pointer to a message created with wimax_msg_alloc()
 */
const void *wimax_msg_data(struct sk_buff *msg)
{
	struct nlmsghdr *nlh = (void *) msg->head;
	struct nlattr *nla;

	nla = nlmsg_find_attr(nlh, sizeof(struct genlmsghdr),
			      WIMAX_GNL_MSG_DATA);
	if (nla == NULL) {
		printk(KERN_ERR "Cannot find attribute WIMAX_GNL_MSG_DATA\n");
		return NULL;
	}
	return nla_data(nla);
}
EXPORT_SYMBOL_GPL(wimax_msg_data);


/**
 * wimax_msg_len - Return a message's payload length
 *
 * @msg: Pointer to a message created with wimax_msg_alloc()
 */
ssize_t wimax_msg_len(struct sk_buff *msg)
{
	struct nlmsghdr *nlh = (void *) msg->head;
	struct nlattr *nla;

	nla = nlmsg_find_attr(nlh, sizeof(struct genlmsghdr),
			      WIMAX_GNL_MSG_DATA);
	if (nla == NULL) {
		printk(KERN_ERR "Cannot find attribute WIMAX_GNL_MSG_DATA\n");
		return -EINVAL;
	}
	return nla_len(nla);
}
EXPORT_SYMBOL_GPL(wimax_msg_len);


/**
 * wimax_msg_send - Send a pre-allocated message to user space
 *
 * @wimax_dev: WiMAX device descriptor
 *
 * @skb: &struct sk_buff returned by wimax_msg_alloc(). Note the
 *     ownership of @skb is transferred to this function.
 *
 * Returns: 0 if ok, < 0 errno code on error
 *
 * Description:
 *
 * Sends a free-form message that was preallocated with
 * wimax_msg_alloc() and filled up.
 *
 * Assumes that once you pass an skb to this function for sending, it
 * owns it and will release it when done (on success).
 *
 * IMPORTANT:
 *
 * Don't use skb_push()/skb_pull()/skb_reserve() on the skb, as
 * wimax_msg_send() depends on skb->data being placed at the
 * beginning of the user message.
 *
 * Unlike other WiMAX stack calls, this call can be used way early,
 * even before wimax_dev_add() is called, as long as the
 * wimax_dev->net_dev pointer is set to point to a proper
 * net_dev. This is so that drivers can use it early in case they need
 * to send stuff around or communicate with user space.
 */
int wimax_msg_send(struct wimax_dev *wimax_dev, struct sk_buff *skb)
{
	struct device *dev = wimax_dev_to_dev(wimax_dev);
	void *msg = skb->data;
	size_t size = skb->len;
	might_sleep();

	d_printf(1, dev, "CTX: wimax msg, %zu bytes\n", size);
	d_dump(2, dev, msg, size);
	genlmsg_multicast(skb, 0, wimax_gnl_mcg.id, GFP_KERNEL);
	d_printf(1, dev, "CTX: genl multicast done\n");
	return 0;
}
EXPORT_SYMBOL_GPL(wimax_msg_send);


/**
 * wimax_msg - Send a message to user space
 *
 * @wimax_dev: WiMAX device descriptor (properly referenced)
 * @pipe_name: "named pipe" the message will be sent to
 * @buf: pointer to the message to send.
 * @size: size of the buffer pointed to by @buf (in bytes).
 * @gfp_flags: flags for memory allocation.
 *
 * Returns: %0 if ok, negative errno code on error.
 *
 * Description:
 *
 * Sends a free-form message to user space on the device @wimax_dev.
 *
 * NOTES:
 *
 * Once the @skb is given to this function, who will own it and will
 * release it when done (unless it returns error).
 */
int wimax_msg(struct wimax_dev *wimax_dev, const char *pipe_name,
	      const void *buf, size_t size, gfp_t gfp_flags)
{
	int result = -ENOMEM;
	struct sk_buff *skb;

	skb = wimax_msg_alloc(wimax_dev, pipe_name, buf, size, gfp_flags);
	if (IS_ERR(skb))
		result = PTR_ERR(skb);
	else
		result = wimax_msg_send(wimax_dev, skb);
	return result;
}
EXPORT_SYMBOL_GPL(wimax_msg);


static const struct nla_policy wimax_gnl_msg_policy[WIMAX_GNL_ATTR_MAX + 1] = {
	[WIMAX_GNL_MSG_IFIDX] = {
		.type = NLA_U32,
	},
	[WIMAX_GNL_MSG_DATA] = {
		.type = NLA_UNSPEC,	/* libnl doesn't grok BINARY yet */
	},
};


/*
 * Relays a message from user space to the driver
 *
 * The skb is passed to the driver-specific function with the netlink
 * and generic netlink headers already stripped.
 *
 * This call will block while handling/relaying the message.
 */
static
int wimax_gnl_doit_msg_from_user(struct sk_buff *skb, struct genl_info *info)
{
	int result, ifindex;
	struct wimax_dev *wimax_dev;
	struct device *dev;
	struct nlmsghdr *nlh = info->nlhdr;
	char *pipe_name;
	void *msg_buf;
	size_t msg_len;

	might_sleep();
	d_fnstart(3, NULL, "(skb %p info %p)\n", skb, info);
	result = -ENODEV;
	if (info->attrs[WIMAX_GNL_MSG_IFIDX] == NULL) {
		printk(KERN_ERR "WIMAX_GNL_MSG_FROM_USER: can't find IFIDX "
		       "attribute\n");
		goto error_no_wimax_dev;
	}
	ifindex = nla_get_u32(info->attrs[WIMAX_GNL_MSG_IFIDX]);
	wimax_dev = wimax_dev_get_by_genl_info(info, ifindex);
	if (wimax_dev == NULL)
		goto error_no_wimax_dev;
	dev = wimax_dev_to_dev(wimax_dev);

	/* Unpack arguments */
	result = -EINVAL;
	if (info->attrs[WIMAX_GNL_MSG_DATA] == NULL) {
		dev_err(dev, "WIMAX_GNL_MSG_FROM_USER: can't find MSG_DATA "
			"attribute\n");
		goto error_no_data;
	}
	msg_buf = nla_data(info->attrs[WIMAX_GNL_MSG_DATA]);
	msg_len = nla_len(info->attrs[WIMAX_GNL_MSG_DATA]);

	if (info->attrs[WIMAX_GNL_MSG_PIPE_NAME] == NULL)
		pipe_name = NULL;
	else {
		struct nlattr *attr = info->attrs[WIMAX_GNL_MSG_PIPE_NAME];
		size_t attr_len = nla_len(attr);
		/* libnl-1.1 does not yet support NLA_NUL_STRING */
		result = -ENOMEM;
		pipe_name = kstrndup(nla_data(attr), attr_len + 1, GFP_KERNEL);
		if (pipe_name == NULL)
			goto error_alloc;
		pipe_name[attr_len] = 0;
	}
	mutex_lock(&wimax_dev->mutex);
	result = wimax_dev_is_ready(wimax_dev);
	if (result == -ENOMEDIUM)
		result = 0;
	if (result < 0)
		goto error_not_ready;
	result = -ENOSYS;
	if (wimax_dev->op_msg_from_user == NULL)
		goto error_noop;

	d_printf(1, dev,
		 "CRX: nlmsghdr len %u type %u flags 0x%04x seq 0x%x pid %u\n",
		 nlh->nlmsg_len, nlh->nlmsg_type, nlh->nlmsg_flags,
		 nlh->nlmsg_seq, nlh->nlmsg_pid);
	d_printf(1, dev, "CRX: wimax message %zu bytes\n", msg_len);
	d_dump(2, dev, msg_buf, msg_len);

	result = wimax_dev->op_msg_from_user(wimax_dev, pipe_name,
					     msg_buf, msg_len, info);
error_noop:
error_not_ready:
	mutex_unlock(&wimax_dev->mutex);
error_alloc:
	kfree(pipe_name);
error_no_data:
	dev_put(wimax_dev->net_dev);
error_no_wimax_dev:
	d_fnend(3, NULL, "(skb %p info %p) = %d\n", skb, info, result);
	return result;
}


/*
 * Generic Netlink glue
 */

struct genl_ops wimax_gnl_msg_from_user = {
	.cmd = WIMAX_GNL_OP_MSG_FROM_USER,
	.flags = GENL_ADMIN_PERM,
	.policy = wimax_gnl_msg_policy,
	.doit = wimax_gnl_doit_msg_from_user,
	.dumpit = NULL,
};