net/wimax/op-msg.c

   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  */
 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  */
 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  */
 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  */
 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  */
 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  */
 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  */
 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 }