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 <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  */
 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  */
 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                 printk(KERN_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  */
 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                 printk(KERN_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  */
 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                 printk(KERN_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  */
 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  */
 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  */
 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                 printk(KERN_ERR "WIMAX_GNL_MSG_FROM_USER: can't find IFIDX "
 347                        "attribute\n");
 348                 goto error_no_wimax_dev;
 349         }
 350         ifindex = nla_get_u32(info->attrs[WIMAX_GNL_MSG_IFIDX]);
 351         wimax_dev = wimax_dev_get_by_genl_info(info, ifindex);
 352         if (wimax_dev == NULL)
 353                 goto error_no_wimax_dev;
 354         dev = wimax_dev_to_dev(wimax_dev);
 355
 356         /* Unpack arguments */
 357         result = -EINVAL;
 358         if (info->attrs[WIMAX_GNL_MSG_DATA] == NULL) {
 359                 dev_err(dev, "WIMAX_GNL_MSG_FROM_USER: can't find MSG_DATA "
 360                         "attribute\n");
 361                 goto error_no_data;
 362         }
 363         msg_buf = nla_data(info->attrs[WIMAX_GNL_MSG_DATA]);
 364         msg_len = nla_len(info->attrs[WIMAX_GNL_MSG_DATA]);
 365
 366         if (info->attrs[WIMAX_GNL_MSG_PIPE_NAME] == NULL)
 367                 pipe_name = NULL;
 368         else {
 369                 struct nlattr *attr = info->attrs[WIMAX_GNL_MSG_PIPE_NAME];
 370                 size_t attr_len = nla_len(attr);
 371                 /* libnl-1.1 does not yet support NLA_NUL_STRING */
 372                 result = -ENOMEM;
 373                 pipe_name = kstrndup(nla_data(attr), attr_len + 1, GFP_KERNEL);
 374                 if (pipe_name == NULL)
 375                         goto error_alloc;
 376                 pipe_name[attr_len] = 0;
 377         }
 378         mutex_lock(&wimax_dev->mutex);
 379         result = wimax_dev_is_ready(wimax_dev);
 380         if (result == -ENOMEDIUM)
 381                 result = 0;
 382         if (result < 0)
 383                 goto error_not_ready;
 384         result = -ENOSYS;
 385         if (wimax_dev->op_msg_from_user == NULL)
 386                 goto error_noop;
 387
 388         d_printf(1, dev,
 389                  "CRX: nlmsghdr len %u type %u flags 0x%04x seq 0x%x pid %u\n",
 390                  nlh->nlmsg_len, nlh->nlmsg_type, nlh->nlmsg_flags,
 391                  nlh->nlmsg_seq, nlh->nlmsg_pid);
 392         d_printf(1, dev, "CRX: wimax message %zu bytes\n", msg_len);
 393         d_dump(2, dev, msg_buf, msg_len);
 394
 395         result = wimax_dev->op_msg_from_user(wimax_dev, pipe_name,
 396                                              msg_buf, msg_len, info);
 397 error_noop:
 398 error_not_ready:
 399         mutex_unlock(&wimax_dev->mutex);
 400 error_alloc:
 401         kfree(pipe_name);
 402 error_no_data:
 403         dev_put(wimax_dev->net_dev);
 404 error_no_wimax_dev:
 405         d_fnend(3, NULL, "(skb %p info %p) = %d\n", skb, info, result);
 406         return result;
 407 }
 408