net/wimax/op-msg.c

   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 <net/genetlink.h>
  76 #include <linux/netdevice.h>
  77 #include <linux/wimax.h>
  78 #include <linux/security.h>
  79 #include "wimax-internal.h"
  80
  81
  82 #define D_SUBMODULE op_msg
  83 #include "debug-levels.h"
  84
  85
  86 /**
  87  * wimax_msg_alloc - Create a new skb for sending a message to userspace
  88  *
  89  * @wimax_dev: WiMAX device descriptor
  90  * @pipe_name: "named pipe" the message will be sent to
  91  * @msg: pointer to the message data to send
  92  * @size: size of the message to send (in bytes), including the header.
  93  * @gfp_flags: flags for memory allocation.
  94  *
  95  * Returns: %0 if ok, negative errno code on error
  96  *
  97  * Description:
  98  *
  99  * Allocates an skb that will contain the message to send to user
 100  * space over the messaging pipe and initializes it, copying the
 101  * payload.
 102  *
 103  * Once this call is done, you can deliver it with
 104  * wimax_msg_send().
 105  *
 106  * IMPORTANT:
 107  *
 108  * Don't use skb_push()/skb_pull()/skb_reserve() on the skb, as
 109  * wimax_msg_send() depends on skb->data being placed at the
 110  * beginning of the user message.
 111  *
 112  * Unlike other WiMAX stack calls, this call can be used way early,
 113  * even before wimax_dev_add() is called, as long as the
 114  * wimax_dev->net_dev pointer is set to point to a proper
 115  * net_dev. This is so that drivers can use it early in case they need
 116  * to send stuff around or communicate with user space.
 117  */
 118 struct sk_buff *wimax_msg_alloc(struct wimax_dev *wimax_dev,
 119                                 const char *pipe_name,
 120                                 const void *msg, size_t size,
 121                                 gfp_t gfp_flags)
 122 {
 123         int result;
 124         struct device *dev = wimax_dev_to_dev(wimax_dev);
 125         size_t msg_size;
 126         void *genl_msg;
 127         struct sk_buff *skb;
 128
 129         msg_size = nla_total_size(size)
 130                 + nla_total_size(sizeof(u32))
 131                 + (pipe_name ? nla_total_size(strlen(pipe_name)) : 0);
 132         result = -ENOMEM;
 133         skb = genlmsg_new(msg_size, gfp_flags);
 134         if (skb == NULL)
 135                 goto error_new;
 136         genl_msg = genlmsg_put(skb, 0, 0, &wimax_gnl_family,
 137                                0, WIMAX_GNL_OP_MSG_TO_USER);
 138         if (genl_msg == NULL) {
 139                 dev_err(dev, "no memory to create generic netlink message\n");
 140                 goto error_genlmsg_put;
 141         }
 142         result = nla_put_u32(skb, WIMAX_GNL_MSG_IFIDX,
 143                              wimax_dev->net_dev->ifindex);
 144         if (result < 0) {
 145                 dev_err(dev, "no memory to add ifindex attribute\n");
 146                 goto error_nla_put;
 147         }
 148         if (pipe_name) {
 149                 result = nla_put_string(skb, WIMAX_GNL_MSG_PIPE_NAME,
 150                                         pipe_name);
 151                 if (result < 0) {
 152                         dev_err(dev, "no memory to add pipe_name attribute\n");
 153                         goto error_nla_put;
 154                 }
 155         }
 156         result = nla_put(skb, WIMAX_GNL_MSG_DATA, size, msg);
 157         if (result < 0) {
 158                 dev_err(dev, "no memory to add payload (msg %p size %zu) in "
 159                         "attribute: %d\n", msg, size, result);
 160                 goto error_nla_put;
 161         }
 162         genlmsg_end(skb, genl_msg);
 163         return skb;
 164
 165 error_nla_put:
 166 error_genlmsg_put:
 167 error_new:
 168         nlmsg_free(skb);
 169         return ERR_PTR(result);
 170 }
 171 EXPORT_SYMBOL_GPL(wimax_msg_alloc);
 172
 173
 174 /**
 175  * wimax_msg_data_len - Return a pointer and size of a message's payload
 176  *
 177  * @msg: Pointer to a message created with wimax_msg_alloc()
 178  * @size: Pointer to where to store the message's size
 179  *
 180  * Returns the pointer to the message data.
 181  */
 182 const void *wimax_msg_data_len(struct sk_buff *msg, size_t *size)
 183 {
 184         struct nlmsghdr *nlh = (void *) msg->head;
 185         struct nlattr *nla;
 186
 187         nla = nlmsg_find_attr(nlh, sizeof(struct genlmsghdr),
 188                               WIMAX_GNL_MSG_DATA);
 189         if (nla == NULL) {
 190                 printk(KERN_ERR "Cannot find attribute WIMAX_GNL_MSG_DATA\n");
 191                 return NULL;
 192         }
 193         *size = nla_len(nla);
 194         return nla_data(nla);
 195 }
 196 EXPORT_SYMBOL_GPL(wimax_msg_data_len);
 197
 198
 199 /**
 200  * wimax_msg_data - Return a pointer to a message's payload
 201  *
 202  * @msg: Pointer to a message created with wimax_msg_alloc()
 203  */
 204 const void *wimax_msg_data(struct sk_buff *msg)
 205 {
 206         struct nlmsghdr *nlh = (void *) msg->head;
 207         struct nlattr *nla;
 208
 209         nla = nlmsg_find_attr(nlh, sizeof(struct genlmsghdr),
 210                               WIMAX_GNL_MSG_DATA);
 211         if (nla == NULL) {
 212                 printk(KERN_ERR "Cannot find attribute WIMAX_GNL_MSG_DATA\n");
 213                 return NULL;
 214         }
 215         return nla_data(nla);
 216 }
 217 EXPORT_SYMBOL_GPL(wimax_msg_data);
 218
 219
 220 /**
 221  * wimax_msg_len - Return a message's payload length
 222  *
 223  * @msg: Pointer to a message created with wimax_msg_alloc()
 224  */
 225 ssize_t wimax_msg_len(struct sk_buff *msg)
 226 {
 227         struct nlmsghdr *nlh = (void *) msg->head;
 228         struct nlattr *nla;
 229
 230         nla = nlmsg_find_attr(nlh, sizeof(struct genlmsghdr),
 231                               WIMAX_GNL_MSG_DATA);
 232         if (nla == NULL) {
 233                 printk(KERN_ERR "Cannot find attribute WIMAX_GNL_MSG_DATA\n");
 234                 return -EINVAL;
 235         }
 236         return nla_len(nla);
 237 }
 238 EXPORT_SYMBOL_GPL(wimax_msg_len);
 239
 240
 241 /**
 242  * wimax_msg_send - Send a pre-allocated message to user space
 243  *
 244  * @wimax_dev: WiMAX device descriptor
 245  *
 246  * @skb: &struct sk_buff returned by wimax_msg_alloc(). Note the
 247  *     ownership of @skb is transferred to this function.
 248  *
 249  * Returns: 0 if ok, < 0 errno code on error
 250  *
 251  * Description:
 252  *
 253  * Sends a free-form message that was preallocated with
 254  * wimax_msg_alloc() and filled up.
 255  *
 256  * Assumes that once you pass an skb to this function for sending, it
 257  * owns it and will release it when done (on success).
 258  *
 259  * IMPORTANT:
 260  *
 261  * Don't use skb_push()/skb_pull()/skb_reserve() on the skb, as
 262  * wimax_msg_send() depends on skb->data being placed at the
 263  * beginning of the user message.
 264  *
 265  * Unlike other WiMAX stack calls, this call can be used way early,
 266  * even before wimax_dev_add() is called, as long as the
 267  * wimax_dev->net_dev pointer is set to point to a proper
 268  * net_dev. This is so that drivers can use it early in case they need
 269  * to send stuff around or communicate with user space.
 270  */
 271 int wimax_msg_send(struct wimax_dev *wimax_dev, struct sk_buff *skb)
 272 {
 273         struct device *dev = wimax_dev_to_dev(wimax_dev);
 274         void *msg = skb->data;
 275         size_t size = skb->len;
 276         might_sleep();
 277
 278         d_printf(1, dev, "CTX: wimax msg, %zu bytes\n", size);
 279         d_dump(2, dev, msg, size);
 280         genlmsg_multicast(skb, 0, wimax_gnl_mcg.id, GFP_KERNEL);
 281         d_printf(1, dev, "CTX: genl multicast done\n");
 282         return 0;
 283 }
 284 EXPORT_SYMBOL_GPL(wimax_msg_send);
 285
 286
 287 /**
 288  * wimax_msg - Send a message to user space
 289  *
 290  * @wimax_dev: WiMAX device descriptor (properly referenced)
 291  * @pipe_name: "named pipe" the message will be sent to
 292  * @buf: pointer to the message to send.
 293  * @size: size of the buffer pointed to by @buf (in bytes).
 294  * @gfp_flags: flags for memory allocation.
 295  *
 296  * Returns: %0 if ok, negative errno code on error.
 297  *
 298  * Description:
 299  *
 300  * Sends a free-form message to user space on the device @wimax_dev.
 301  *
 302  * NOTES:
 303  *
 304  * Once the @skb is given to this function, who will own it and will
 305  * release it when done (unless it returns error).
 306  */
 307 int wimax_msg(struct wimax_dev *wimax_dev, const char *pipe_name,
 308               const void *buf, size_t size, gfp_t gfp_flags)
 309 {
 310         int result = -ENOMEM;
 311         struct sk_buff *skb;
 312
 313         skb = wimax_msg_alloc(wimax_dev, pipe_name, buf, size, gfp_flags);
 314         if (IS_ERR(skb))
 315                 result = PTR_ERR(skb);
 316         else
 317                 result = wimax_msg_send(wimax_dev, skb);
 318         return result;
 319 }
 320 EXPORT_SYMBOL_GPL(wimax_msg);
 321
 322
 323 static const
 324 struct nla_policy wimax_gnl_msg_policy[WIMAX_GNL_ATTR_MAX + 1] = {
 325         [WIMAX_GNL_MSG_IFIDX] = {
 326                 .type = NLA_U32,
 327         },
 328         [WIMAX_GNL_MSG_DATA] = {
 329                 .type = NLA_UNSPEC,     /* libnl doesn't grok BINARY yet */
 330         },
 331 };
 332
 333
 334 /*
 335  * Relays a message from user space to the driver
 336  *
 337  * The skb is passed to the driver-specific function with the netlink
 338  * and generic netlink headers already stripped.
 339  *
 340  * This call will block while handling/relaying the message.
 341  */
 342 static
 343 int wimax_gnl_doit_msg_from_user(struct sk_buff *skb, struct genl_info *info)
 344 {
 345         int result, ifindex;
 346         struct wimax_dev *wimax_dev;
 347         struct device *dev;
 348         struct nlmsghdr *nlh = info->nlhdr;
 349         char *pipe_name;
 350         void *msg_buf;
 351         size_t msg_len;
 352
 353         might_sleep();
 354         d_fnstart(3, NULL, "(skb %p info %p)\n", skb, info);
 355         result = -ENODEV;
 356         if (info->attrs[WIMAX_GNL_MSG_IFIDX] == NULL) {
 357                 printk(KERN_ERR "WIMAX_GNL_MSG_FROM_USER: can't find IFIDX "
 358                        "attribute\n");
 359                 goto error_no_wimax_dev;
 360         }
 361         ifindex = nla_get_u32(info->attrs[WIMAX_GNL_MSG_IFIDX]);
 362         wimax_dev = wimax_dev_get_by_genl_info(info, ifindex);
 363         if (wimax_dev == NULL)
 364                 goto error_no_wimax_dev;
 365         dev = wimax_dev_to_dev(wimax_dev);
 366
 367         /* Unpack arguments */
 368         result = -EINVAL;
 369         if (info->attrs[WIMAX_GNL_MSG_DATA] == NULL) {
 370                 dev_err(dev, "WIMAX_GNL_MSG_FROM_USER: can't find MSG_DATA "
 371                         "attribute\n");
 372                 goto error_no_data;
 373         }
 374         msg_buf = nla_data(info->attrs[WIMAX_GNL_MSG_DATA]);
 375         msg_len = nla_len(info->attrs[WIMAX_GNL_MSG_DATA]);
 376
 377         if (info->attrs[WIMAX_GNL_MSG_PIPE_NAME] == NULL)
 378                 pipe_name = NULL;
 379         else {
 380                 struct nlattr *attr = info->attrs[WIMAX_GNL_MSG_PIPE_NAME];
 381                 size_t attr_len = nla_len(attr);
 382                 /* libnl-1.1 does not yet support NLA_NUL_STRING */
 383                 result = -ENOMEM;
 384                 pipe_name = kstrndup(nla_data(attr), attr_len + 1, GFP_KERNEL);
 385                 if (pipe_name == NULL)
 386                         goto error_alloc;
 387                 pipe_name[attr_len] = 0;
 388         }
 389         mutex_lock(&wimax_dev->mutex);
 390         result = wimax_dev_is_ready(wimax_dev);
 391         if (result < 0)
 392                 goto error_not_ready;
 393         result = -ENOSYS;
 394         if (wimax_dev->op_msg_from_user == NULL)
 395                 goto error_noop;
 396
 397         d_printf(1, dev,
 398                  "CRX: nlmsghdr len %u type %u flags 0x%04x seq 0x%x pid %u\n",
 399                  nlh->nlmsg_len, nlh->nlmsg_type, nlh->nlmsg_flags,
 400                  nlh->nlmsg_seq, nlh->nlmsg_pid);
 401         d_printf(1, dev, "CRX: wimax message %zu bytes\n", msg_len);
 402         d_dump(2, dev, msg_buf, msg_len);
 403
 404         result = wimax_dev->op_msg_from_user(wimax_dev, pipe_name,
 405                                              msg_buf, msg_len, info);
 406 error_noop:
 407 error_not_ready:
 408         mutex_unlock(&wimax_dev->mutex);
 409 error_alloc:
 410         kfree(pipe_name);
 411 error_no_data:
 412         dev_put(wimax_dev->net_dev);
 413 error_no_wimax_dev:
 414         d_fnend(3, NULL, "(skb %p info %p) = %d\n", skb, info, result);
 415         return result;
 416 }
 417
 418
 419 /*
 420  * Generic Netlink glue
 421  */
 422
 423 struct genl_ops wimax_gnl_msg_from_user = {
 424         .cmd = WIMAX_GNL_OP_MSG_FROM_USER,
 425         .flags = GENL_ADMIN_PERM,
 426         .policy = wimax_gnl_msg_policy,
 427         .doit = wimax_gnl_doit_msg_from_user,
 428         .dumpit = NULL,
 429 };
 430