sys/netlink/netlink_generic.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
   3  *
   4  * Copyright (c) 2022 Alexander V. Chernikov <melifaro@FreeBSD.org>
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  18  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  25  * SUCH DAMAGE.
  26  */
  27
  28 #include <sys/cdefs.h>
  29 __FBSDID("$FreeBSD$");
  30 #include <sys/types.h>
  31 #include <sys/ck.h>
  32 #include <sys/kernel.h>
  33 #include <sys/lock.h>
  34 #include <sys/malloc.h>
  35 #include <sys/priv.h>
  36 #include <sys/socket.h>
  37 #include <sys/sx.h>
  38
  39 #include <netlink/netlink.h>
  40 #include <netlink/netlink_ctl.h>
  41 #include <netlink/netlink_var.h>
  42 #include <netlink/netlink_generic.h>
  43
  44 #define DEBUG_MOD_NAME  nl_generic
  45 #define DEBUG_MAX_LEVEL LOG_DEBUG3
  46 #include <netlink/netlink_debug.h>
  47 _DECLARE_DEBUG(LOG_DEBUG3);
  48
  49 #define MAX_FAMILIES    20
  50 #define MAX_GROUPS      20
  51
  52 #define MIN_GROUP_NUM   48
  53
  54 static struct sx sx_lock;
  55
  56 #define GENL_LOCK_INIT()        sx_init(&sx_lock, "genetlink lock")
  57 #define GENL_LOCK_DESTROY()     sx_destroy(&sx_lock)
  58 #define GENL_LOCK()             sx_xlock(&sx_lock)
  59 #define GENL_UNLOCK()           sx_xunlock(&sx_lock)
  60
  61 struct genl_family {
  62         const char      *family_name;
  63         uint16_t        family_hdrsize;
  64         uint16_t        family_id;
  65         uint16_t        family_version;
  66         uint16_t        family_attr_max;
  67         uint16_t        family_cmd_size;
  68         uint16_t        family_num_groups;
  69         struct genl_cmd *family_cmds;
  70 };
  71
  72 static struct genl_family       families[MAX_FAMILIES];
  73
  74
  75 struct genl_group {
  76         struct genl_family      *group_family;
  77         const char              *group_name;
  78 };
  79 static struct genl_group        groups[MAX_GROUPS];
  80
  81
  82 static int dump_family(struct nlmsghdr *hdr, struct genlmsghdr *ghdr,
  83     const struct genl_family *gf, struct nl_writer *nw);
  84 static void nlctrl_notify(const struct genl_family *gf, int action);
  85
  86 static struct genl_family *
  87 find_family(const char *family_name)
  88 {
  89         for (int i = 0; i < MAX_FAMILIES; i++) {
  90                 struct genl_family *gf = &families[i];
  91                 if (gf->family_name != NULL && !strcmp(gf->family_name, family_name))
  92                         return (gf);
  93         }
  94
  95         return (NULL);
  96 }
  97
  98 uint32_t
  99 genl_register_family(const char *family_name, size_t hdrsize, int family_version,
 100     int max_attr_idx)
 101 {
 102         uint32_t family_id = 0;
 103
 104         MPASS(family_name != NULL);
 105         if (find_family(family_name) != NULL)
 106                 return (0);
 107
 108         GENL_LOCK();
 109         for (int i = 0; i < MAX_FAMILIES; i++) {
 110                 struct genl_family *gf = &families[i];
 111                 if (gf->family_name == NULL) {
 112                         gf->family_name = family_name;
 113                         gf->family_version = family_version;
 114                         gf->family_hdrsize = hdrsize;
 115                         gf->family_attr_max = max_attr_idx;
 116                         gf->family_id = i + GENL_MIN_ID;
 117                         NL_LOG(LOG_DEBUG2, "Registered family %s id %d",
 118                             gf->family_name, gf->family_id);
 119                         family_id = gf->family_id;
 120                         nlctrl_notify(gf, CTRL_CMD_NEWFAMILY);
 121                         break;
 122                 }
 123         }
 124         GENL_UNLOCK();
 125
 126         return (family_id);
 127 }
 128
 129 static void
 130 free_family(struct genl_family *gf)
 131 {
 132         if (gf->family_cmds != NULL)
 133                 free(gf->family_cmds, M_NETLINK);
 134 }
 135
 136 /*
 137  * Can sleep, I guess
 138  */
 139 bool
 140 genl_unregister_family(const char *family_name)
 141 {
 142         bool found = false;
 143
 144         GENL_LOCK();
 145         struct genl_family *gf = find_family(family_name);
 146
 147         nlctrl_notify(gf, CTRL_CMD_DELFAMILY);
 148
 149         if (gf != NULL) {
 150                 found = true;
 151                 /* TODO: zero pointer first */
 152                 free_family(gf);
 153                 bzero(gf, sizeof(*gf));
 154         }
 155         GENL_UNLOCK();
 156
 157         return (found);
 158 }
 159
 160 bool
 161 genl_register_cmds(const char *family_name, const struct genl_cmd *cmds, int count)
 162 {
 163         GENL_LOCK();
 164         struct genl_family *gf = find_family(family_name);
 165         if (gf == NULL) {
 166                 GENL_UNLOCK();
 167                 return (false);
 168         }
 169
 170         int cmd_size = gf->family_cmd_size;
 171
 172         for (int i = 0; i < count; i++) {
 173                 MPASS(cmds[i].cmd_cb != NULL);
 174                 if (cmds[i].cmd_num >= cmd_size)
 175                         cmd_size = cmds[i].cmd_num + 1;
 176         }
 177
 178         if (cmd_size > gf->family_cmd_size) {
 179                 /* need to realloc */
 180                 size_t sz = cmd_size * sizeof(struct genl_cmd);
 181                 void *data = malloc(sz, M_NETLINK, M_WAITOK | M_ZERO);
 182
 183                 memcpy(data, gf->family_cmds, gf->family_cmd_size * sizeof(struct genl_cmd));
 184                 void *old_data = gf->family_cmds;
 185                 gf->family_cmds = data;
 186                 gf->family_cmd_size = cmd_size;
 187                 free(old_data, M_NETLINK);
 188         }
 189
 190         for (int i = 0; i < count; i++) {
 191                 const struct genl_cmd *cmd = &cmds[i];
 192                 MPASS(gf->family_cmds[cmd->cmd_num].cmd_cb == NULL);
 193                 gf->family_cmds[cmd->cmd_num] = cmds[i];
 194                 NL_LOG(LOG_DEBUG2, "Adding cmd %s(%d) to family %s",
 195                     cmd->cmd_name, cmd->cmd_num, gf->family_name);
 196         }
 197         GENL_UNLOCK();
 198         return (true);
 199 }
 200
 201 static struct genl_group *
 202 find_group(const struct genl_family *gf, const char *group_name)
 203 {
 204         for (int i = 0; i < MAX_GROUPS; i++) {
 205                 struct genl_group *gg = &groups[i];
 206                 if (gg->group_family == gf && !strcmp(gg->group_name, group_name))
 207                         return (gg);
 208         }
 209         return (NULL);
 210 }
 211
 212 uint32_t
 213 genl_register_group(const char *family_name, const char *group_name)
 214 {
 215         uint32_t group_id = 0;
 216
 217         MPASS(family_name != NULL);
 218         MPASS(group_name != NULL);
 219
 220         GENL_LOCK();
 221         struct genl_family *gf = find_family(family_name);
 222
 223         if (gf == NULL || find_group(gf, group_name) != NULL) {
 224                 GENL_UNLOCK();
 225                 return (0);
 226         }
 227
 228         for (int i = 0; i < MAX_GROUPS; i++) {
 229                 struct genl_group *gg = &groups[i];
 230                 if (gg->group_family == NULL) {
 231                         gf->family_num_groups++;
 232                         gg->group_family = gf;
 233                         gg->group_name = group_name;
 234                         group_id = i + MIN_GROUP_NUM;
 235                         break;
 236                 }
 237         }
 238         GENL_UNLOCK();
 239
 240         return (group_id);
 241 }
 242
 243 /*
 244  * Handler called by netlink subsystem when matching netlink message is received
 245  */
 246 static int
 247 genl_handle_message(struct nlmsghdr *hdr, struct nl_pstate *npt)
 248 {
 249         struct nlpcb *nlp = npt->nlp;
 250         int error = 0;
 251
 252         int family_id = (int)hdr->nlmsg_type - GENL_MIN_ID;
 253
 254         if (__predict_false(family_id < 0 || family_id > MAX_FAMILIES)) {
 255                 NLP_LOG(LOG_DEBUG, nlp, "invalid message type: %d", hdr->nlmsg_type);
 256                 return (ENOTSUP);
 257         }
 258
 259         if (__predict_false(hdr->nlmsg_len < sizeof(hdr) + GENL_HDRLEN)) {
 260                 NLP_LOG(LOG_DEBUG, nlp, "invalid message size: %d", hdr->nlmsg_len);
 261                 return (EINVAL);
 262         }
 263
 264         struct genl_family *gf = &families[family_id];
 265
 266         struct genlmsghdr *ghdr = (struct genlmsghdr *)(hdr + 1);
 267
 268         if (ghdr->cmd >= gf->family_cmd_size || gf->family_cmds[ghdr->cmd].cmd_cb == NULL) {
 269                 NLP_LOG(LOG_DEBUG, nlp, "family %s: invalid cmd %d",
 270                     gf->family_name, ghdr->cmd);
 271                 return (ENOTSUP);
 272         }
 273
 274         struct genl_cmd *cmd = &gf->family_cmds[ghdr->cmd];
 275
 276         if (cmd->cmd_priv != 0 && !nlp_has_priv(nlp, cmd->cmd_priv)) {
 277                 NLP_LOG(LOG_DEBUG, nlp, "family %s: cmd %d priv_check() failed",
 278                     gf->family_name, ghdr->cmd);
 279                 return (EPERM);
 280         }
 281
 282         NLP_LOG(LOG_DEBUG2, nlp, "received family %s cmd %s(%d) len %d",
 283             gf->family_name, cmd->cmd_name, ghdr->cmd, hdr->nlmsg_len);
 284
 285         error = cmd->cmd_cb(hdr, npt);
 286
 287         return (error);
 288 }
 289
 290 static uint32_t
 291 get_cmd_flags(const struct genl_cmd *cmd)
 292 {
 293         uint32_t flags = cmd->cmd_flags;
 294         if (cmd->cmd_priv != 0)
 295                 flags |= GENL_ADMIN_PERM;
 296         return (flags);
 297 }
 298
 299 static int
 300 dump_family(struct nlmsghdr *hdr, struct genlmsghdr *ghdr,
 301     const struct genl_family *gf, struct nl_writer *nw)
 302 {
 303         if (!nlmsg_reply(nw, hdr, sizeof(struct genlmsghdr)))
 304                 goto enomem;
 305
 306         struct genlmsghdr *ghdr_new = nlmsg_reserve_object(nw, struct genlmsghdr);
 307         ghdr_new->cmd = ghdr->cmd;
 308         ghdr_new->version = gf->family_version;
 309         ghdr_new->reserved = 0;
 310
 311         nlattr_add_string(nw, CTRL_ATTR_FAMILY_NAME, gf->family_name);
 312         nlattr_add_u16(nw, CTRL_ATTR_FAMILY_ID, gf->family_id);
 313         nlattr_add_u32(nw, CTRL_ATTR_VERSION, gf->family_version);
 314         nlattr_add_u32(nw, CTRL_ATTR_HDRSIZE, gf->family_hdrsize);
 315         nlattr_add_u32(nw, CTRL_ATTR_MAXATTR, gf->family_attr_max);
 316
 317         if (gf->family_cmd_size > 0) {
 318                 int off = nlattr_add_nested(nw, CTRL_ATTR_OPS);
 319                 if (off == 0)
 320                         goto enomem;
 321                 for (int i = 0, cnt=0; i < gf->family_cmd_size; i++) {
 322                         struct genl_cmd *cmd = &gf->family_cmds[i];
 323                         if (cmd->cmd_cb == NULL)
 324                                 continue;
 325                         int cmd_off = nlattr_add_nested(nw, ++cnt);
 326                         if (cmd_off == 0)
 327                                 goto enomem;
 328
 329                         nlattr_add_u32(nw, CTRL_ATTR_OP_ID, cmd->cmd_num);
 330                         nlattr_add_u32(nw, CTRL_ATTR_OP_FLAGS, get_cmd_flags(cmd));
 331                         nlattr_set_len(nw, cmd_off);
 332                 }
 333                 nlattr_set_len(nw, off);
 334         }
 335         if (gf->family_num_groups > 0) {
 336                 int off = nlattr_add_nested(nw, CTRL_ATTR_MCAST_GROUPS);
 337                 if (off == 0)
 338                         goto enomem;
 339                 for (int i = 0, cnt = 0; i < MAX_GROUPS; i++) {
 340                         struct genl_group *gg = &groups[i];
 341                         if (gg->group_family != gf)
 342                                 continue;
 343
 344                         int cmd_off = nlattr_add_nested(nw, ++cnt);
 345                         if (cmd_off == 0)
 346                                 goto enomem;
 347                         nlattr_add_u32(nw, CTRL_ATTR_MCAST_GRP_ID, i + MIN_GROUP_NUM);
 348                         nlattr_add_string(nw, CTRL_ATTR_MCAST_GRP_NAME, gg->group_name);
 349                         nlattr_set_len(nw, cmd_off);
 350                 }
 351                 nlattr_set_len(nw, off);
 352         }
 353         if (nlmsg_end(nw))
 354                 return (0);
 355 enomem:
 356         NL_LOG(LOG_DEBUG, "unable to dump family %s state (ENOMEM)", gf->family_name);
 357         nlmsg_abort(nw);
 358         return (ENOMEM);
 359 }
 360
 361
 362 /* Declare ourself as a user */
 363 #define CTRL_FAMILY_NAME        "nlctrl"
 364
 365 static uint32_t ctrl_family_id;
 366 static uint32_t ctrl_group_id;
 367
 368 struct nl_parsed_family {
 369         uint32_t        family_id;
 370         char            *family_name;
 371         uint8_t         version;
 372 };
 373
 374 #define _IN(_field)     offsetof(struct genlmsghdr, _field)
 375 #define _OUT(_field)    offsetof(struct nl_parsed_family, _field)
 376 static const struct nlfield_parser nlf_p_generic[] = {
 377         { .off_in = _IN(version), .off_out = _OUT(version), .cb = nlf_get_u8 },
 378 };
 379
 380 static struct nlattr_parser nla_p_generic[] = {
 381         { .type = CTRL_ATTR_FAMILY_ID , .off = _OUT(family_id), .cb = nlattr_get_uint32 },
 382         { .type = CTRL_ATTR_FAMILY_NAME , .off = _OUT(family_id), .cb = nlattr_get_string },
 383 };
 384 #undef _IN
 385 #undef _OUT
 386 NL_DECLARE_PARSER(genl_parser, struct genlmsghdr, nlf_p_generic, nla_p_generic);
 387
 388 static int
 389 nlctrl_handle_getfamily(struct nlmsghdr *hdr, struct nl_pstate *npt)
 390 {
 391         int error = 0;
 392
 393         struct nl_parsed_family attrs = {};
 394         error = nl_parse_nlmsg(hdr, &genl_parser, npt, &attrs);
 395         if (error != 0)
 396                 return (error);
 397
 398         struct genlmsghdr ghdr = {
 399                 .cmd = CTRL_CMD_NEWFAMILY,
 400         };
 401
 402         for (int i = 0; i < MAX_FAMILIES; i++) {
 403                 struct genl_family *gf = &families[i];
 404                 if (gf->family_name == NULL)
 405                         continue;
 406                 if (attrs.family_id != 0 && attrs.family_id != gf->family_id)
 407                         continue;
 408                 if (attrs.family_name != NULL && strcmp(attrs.family_name, gf->family_name))
 409                         continue;
 410                 error = dump_family(hdr, &ghdr, &families[i], npt->nw);
 411                 if (error != 0)
 412                         break;
 413         }
 414
 415         return (error);
 416 }
 417
 418 static void
 419 nlctrl_notify(const struct genl_family *gf, int cmd)
 420 {
 421         struct nlmsghdr hdr = {.nlmsg_type = NETLINK_GENERIC };
 422         struct genlmsghdr ghdr = { .cmd = cmd };
 423         struct nl_writer nw = {};
 424
 425         if (nlmsg_get_group_writer(&nw, NLMSG_SMALL, NETLINK_GENERIC, ctrl_group_id)) {
 426                 dump_family(&hdr, &ghdr, gf, &nw);
 427                 nlmsg_flush(&nw);
 428                 return;
 429         }
 430         NL_LOG(LOG_DEBUG, "error allocating group writer");
 431 }
 432
 433 static const struct genl_cmd nlctrl_cmds[] = {
 434         {
 435                 .cmd_num = CTRL_CMD_GETFAMILY,
 436                 .cmd_name = "GETFAMILY",
 437                 .cmd_cb = nlctrl_handle_getfamily,
 438                 .cmd_flags = GENL_CMD_CAP_DO | GENL_CMD_CAP_DUMP, GENL_CMD_CAP_HASPOL,
 439         },
 440 };
 441
 442 static void
 443 genl_nlctrl_init()
 444 {
 445         ctrl_family_id = genl_register_family(CTRL_FAMILY_NAME, 0, 2, CTRL_ATTR_MAX);
 446         genl_register_cmds(CTRL_FAMILY_NAME, nlctrl_cmds, NL_ARRAY_LEN(nlctrl_cmds));
 447         ctrl_group_id = genl_register_group(CTRL_FAMILY_NAME, "notify");
 448 }
 449
 450 static void
 451 genl_nlctrl_destroy()
 452 {
 453         genl_unregister_family(CTRL_FAMILY_NAME);
 454 }
 455
 456 static const struct nlhdr_parser *all_parsers[] = { &genl_parser };
 457
 458 static void
 459 genl_load(void *u __unused)
 460 {
 461         GENL_LOCK_INIT();
 462         NL_VERIFY_PARSERS(all_parsers);
 463         netlink_register_proto(NETLINK_GENERIC, "NETLINK_GENERIC", genl_handle_message);
 464         genl_nlctrl_init();
 465 }
 466 SYSINIT(genl_load, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, genl_load, NULL);
 467
 468 static void
 469 genl_unload(void *u __unused)
 470 {
 471         genl_nlctrl_destroy();
 472         GENL_LOCK_DESTROY();
 473         epoch_wait_preempt(net_epoch_preempt);
 474 }
 475 SYSUNINIT(genl_unload, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, genl_unload, NULL);