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 struct sk_buff *wimax_msg_alloc(struct wimax_dev *wimax_dev,
 113                                 const char *pipe_name,
 114                                 const void *msg, size_t size,
 115                                 gfp_t gfp_flags)
 116 {
 117         int result;
 118         struct device *dev = wimax_dev->net_dev->dev.parent;
 119         size_t msg_size;
 120         void *genl_msg;
 121         struct sk_buff *skb;
 122
 123         msg_size = nla_total_size(size)
 124                 + nla_total_size(sizeof(u32))
 125                 + (pipe_name ? nla_total_size(strlen(pipe_name)) : 0);
 126         result = -ENOMEM;
 127         skb = genlmsg_new(msg_size, gfp_flags);
 128         if (skb == NULL)
 129                 goto error_new;
 130         genl_msg = genlmsg_put(skb, 0, 0, &wimax_gnl_family,
 131                                0, WIMAX_GNL_OP_MSG_TO_USER);
 132         if (genl_msg == NULL) {
 133                 dev_err(dev, "no memory to create generic netlink message\n");
 134                 goto error_genlmsg_put;
 135         }
 136         result = nla_put_u32(skb, WIMAX_GNL_MSG_IFIDX,
 137                              wimax_dev->net_dev->ifindex);
 138         if (result < 0) {
 139                 dev_err(dev, "no memory to add ifindex attribute\n");
 140                 goto error_nla_put;
 141         }
 142         if (pipe_name) {
 143                 result = nla_put_string(skb, WIMAX_GNL_MSG_PIPE_NAME,
 144                                         pipe_name);
 145                 if (result < 0) {
 146                         dev_err(dev, "no memory to add pipe_name attribute\n");
 147                         goto error_nla_put;
 148                 }
 149         }
 150         result = nla_put(skb, WIMAX_GNL_MSG_DATA, size, msg);
 151         if (result < 0) {
 152                 dev_err(dev, "no memory to add payload in attribute\n");
 153                 goto error_nla_put;
 154         }
 155         genlmsg_end(skb, genl_msg);
 156         return skb;
 157
 158 error_nla_put:
 159 error_genlmsg_put:
 160 error_new:
 161         nlmsg_free(skb);
 162         return ERR_PTR(result);
 163
 164 }
 165 EXPORT_SYMBOL_GPL(wimax_msg_alloc);
 166
 167
 168 /**
 169  * wimax_msg_data_len - Return a pointer and size of a message's payload
 170  *
 171  * @msg: Pointer to a message created with wimax_msg_alloc()
 172  * @size: Pointer to where to store the message's size
 173  *
 174  * Returns the pointer to the message data.
 175  */
 176 const void *wimax_msg_data_len(struct sk_buff *msg, size_t *size)
 177 {
 178         struct nlmsghdr *nlh = (void *) msg->head;
 179         struct nlattr *nla;
 180
 181         nla = nlmsg_find_attr(nlh, sizeof(struct genlmsghdr),
 182                               WIMAX_GNL_MSG_DATA);
 183         if (nla == NULL) {
 184                 printk(KERN_ERR "Cannot find attribute WIMAX_GNL_MSG_DATA\n");
 185                 return NULL;
 186         }
 187         *size = nla_len(nla);
 188         return nla_data(nla);
 189 }
 190 EXPORT_SYMBOL_GPL(wimax_msg_data_len);
 191
 192
 193 /**
 194  * wimax_msg_data - Return a pointer to a message's payload
 195  *
 196  * @msg: Pointer to a message created with wimax_msg_alloc()
 197  */
 198 const void *wimax_msg_data(struct sk_buff *msg)
 199 {
 200         struct nlmsghdr *nlh = (void *) msg->head;
 201         struct nlattr *nla;
 202
 203         nla = nlmsg_find_attr(nlh, sizeof(struct genlmsghdr),
 204                               WIMAX_GNL_MSG_DATA);
 205         if (nla == NULL) {
 206                 printk(KERN_ERR "Cannot find attribute WIMAX_GNL_MSG_DATA\n");
 207                 return NULL;
 208         }
 209         return nla_data(nla);
 210 }
 211 EXPORT_SYMBOL_GPL(wimax_msg_data);
 212
 213
 214 /**
 215  * wimax_msg_len - Return a message's payload length
 216  *
 217  * @msg: Pointer to a message created with wimax_msg_alloc()
 218  */
 219 ssize_t wimax_msg_len(struct sk_buff *msg)
 220 {
 221         struct nlmsghdr *nlh = (void *) msg->head;
 222         struct nlattr *nla;
 223
 224         nla = nlmsg_find_attr(nlh, sizeof(struct genlmsghdr),
 225                               WIMAX_GNL_MSG_DATA);
 226         if (nla == NULL) {
 227                 printk(KERN_ERR "Cannot find attribute WIMAX_GNL_MSG_DATA\n");
 228                 return -EINVAL;
 229         }
 230         return nla_len(nla);
 231 }
 232 EXPORT_SYMBOL_GPL(wimax_msg_len);
 233
 234
 235 /**
 236  * wimax_msg_send - Send a pre-allocated message to user space
 237  *
 238  * @wimax_dev: WiMAX device descriptor
 239  *
 240  * @skb: &struct sk_buff returned by wimax_msg_alloc(). Note the
 241  *     ownership of @skb is transferred to this function.
 242  *
 243  * Returns: 0 if ok, < 0 errno code on error
 244  *
 245  * Description:
 246  *
 247  * Sends a free-form message that was preallocated with
 248  * wimax_msg_alloc() and filled up.
 249  *
 250  * Assumes that once you pass an skb to this function for sending, it
 251  * owns it and will release it when done (on success).
 252  *
 253  * IMPORTANT:
 254  *
 255  * Don't use skb_push()/skb_pull()/skb_reserve() on the skb, as
 256  * wimax_msg_send() depends on skb->data being placed at the
 257  * beginning of the user message.
 258  */
 259 int wimax_msg_send(struct wimax_dev *wimax_dev, struct sk_buff *skb)
 260 {
 261         int result;
 262         struct device *dev = wimax_dev->net_dev->dev.parent;
 263         void *msg = skb->data;
 264         size_t size = skb->len;
 265         might_sleep();
 266
 267         d_printf(1, dev, "CTX: wimax msg, %zu bytes\n", size);
 268         d_dump(2, dev, msg, size);
 269         result = genlmsg_multicast(skb, 0, wimax_gnl_mcg.id, GFP_KERNEL);
 270         d_printf(1, dev, "CTX: genl multicast result %d\n", result);
 271         if (result == -ESRCH)   /* Nobody connected, ignore it */
 272                 result = 0;     /* btw, the skb is freed already */
 273         return result;
 274 }
 275 EXPORT_SYMBOL_GPL(wimax_msg_send);
 276
 277
 278 /**
 279  * wimax_msg - Send a message to user space
 280  *
 281  * @wimax_dev: WiMAX device descriptor (properly referenced)
 282  * @pipe_name: "named pipe" the message will be sent to
 283  * @buf: pointer to the message to send.
 284  * @size: size of the buffer pointed to by @buf (in bytes).
 285  * @gfp_flags: flags for memory allocation.
 286  *
 287  * Returns: %0 if ok, negative errno code on error.
 288  *
 289  * Description:
 290  *
 291  * Sends a free-form message to user space on the device @wimax_dev.
 292  *
 293  * NOTES:
 294  *
 295  * Once the @skb is given to this function, who will own it and will
 296  * release it when done (unless it returns error).
 297  */
 298 int wimax_msg(struct wimax_dev *wimax_dev, const char *pipe_name,
 299               const void *buf, size_t size, gfp_t gfp_flags)
 300 {
 301         int result = -ENOMEM;
 302         struct sk_buff *skb;
 303
 304         skb = wimax_msg_alloc(wimax_dev, pipe_name, buf, size, gfp_flags);
 305         if (skb == NULL)
 306                 goto error_msg_new;
 307         result = wimax_msg_send(wimax_dev, skb);
 308 error_msg_new:
 309         return result;
 310 }
 311 EXPORT_SYMBOL_GPL(wimax_msg);
 312
 313
 314 static const
 315 struct nla_policy wimax_gnl_msg_policy[WIMAX_GNL_ATTR_MAX + 1] = {
 316         [WIMAX_GNL_MSG_IFIDX] = {
 317                 .type = NLA_U32,
 318         },
 319         [WIMAX_GNL_MSG_DATA] = {
 320                 .type = NLA_UNSPEC,     /* libnl doesn't grok BINARY yet */
 321         },
 322 };
 323
 324
 325 /*
 326  * Relays a message from user space to the driver
 327  *
 328  * The skb is passed to the driver-specific function with the netlink
 329  * and generic netlink headers already stripped.
 330  *
 331  * This call will block while handling/relaying the message.
 332  */
 333 static
 334 int wimax_gnl_doit_msg_from_user(struct sk_buff *skb, struct genl_info *info)
 335 {
 336         int result, ifindex;
 337         struct wimax_dev *wimax_dev;
 338         struct device *dev;
 339         struct nlmsghdr *nlh = info->nlhdr;
 340         char *pipe_name;
 341         void *msg_buf;
 342         size_t msg_len;
 343
 344         might_sleep();
 345         d_fnstart(3, NULL, "(skb %p info %p)\n", skb, info);
 346         result = -ENODEV;
 347         if (info->attrs[WIMAX_GNL_MSG_IFIDX] == NULL) {
 348                 printk(KERN_ERR "WIMAX_GNL_MSG_FROM_USER: can't find IFIDX "
 349                        "attribute\n");
 350                 goto error_no_wimax_dev;
 351         }
 352         ifindex = nla_get_u32(info->attrs[WIMAX_GNL_MSG_IFIDX]);
 353         wimax_dev = wimax_dev_get_by_genl_info(info, ifindex);
 354         if (wimax_dev == NULL)
 355                 goto error_no_wimax_dev;
 356         dev = wimax_dev_to_dev(wimax_dev);
 357
 358         /* Unpack arguments */
 359         result = -EINVAL;
 360         if (info->attrs[WIMAX_GNL_MSG_DATA] == NULL) {
 361                 dev_err(dev, "WIMAX_GNL_MSG_FROM_USER: can't find MSG_DATA "
 362                         "attribute\n");
 363                 goto error_no_data;
 364         }
 365         msg_buf = nla_data(info->attrs[WIMAX_GNL_MSG_DATA]);
 366         msg_len = nla_len(info->attrs[WIMAX_GNL_MSG_DATA]);
 367
 368         if (info->attrs[WIMAX_GNL_MSG_PIPE_NAME] == NULL)
 369                 pipe_name = NULL;
 370         else {
 371                 struct nlattr *attr = info->attrs[WIMAX_GNL_MSG_PIPE_NAME];
 372                 size_t attr_len = nla_len(attr);
 373                 /* libnl-1.1 does not yet support NLA_NUL_STRING */
 374                 result = -ENOMEM;
 375                 pipe_name = kstrndup(nla_data(attr), attr_len + 1, GFP_KERNEL);
 376                 if (pipe_name == NULL)
 377                         goto error_alloc;
 378                 pipe_name[attr_len] = 0;
 379         }
 380         mutex_lock(&wimax_dev->mutex);
 381         result = wimax_dev_is_ready(wimax_dev);
 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
 409
 410 /*
 411  * Generic Netlink glue
 412  */
 413
 414 struct genl_ops wimax_gnl_msg_from_user = {
 415         .cmd = WIMAX_GNL_OP_MSG_FROM_USER,
 416         .flags = GENL_ADMIN_PERM,
 417         .policy = wimax_gnl_msg_policy,
 418         .doit = wimax_gnl_doit_msg_from_user,
 419         .dumpit = NULL,
 420 };
 421