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/epoch.h>
  33 #include <sys/kernel.h>
  34 #include <sys/lock.h>
  35 #include <sys/malloc.h>
  36 #include <sys/priv.h>
  37 #include <sys/socket.h>
  38 #include <sys/sx.h>
  39
  40 #include <netlink/netlink.h>
  41 #include <netlink/netlink_ctl.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      64
  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  * unregister groups of a given family
 138  */
 139 static void
 140 unregister_groups(const struct genl_family *gf)
 141 {
 142
 143         for (int i = 0; i < MAX_GROUPS; i++) {
 144                 struct genl_group *gg = &groups[i];
 145                 if (gg->group_family == gf && gg->group_name != NULL) {
 146                         gg->group_family = NULL;
 147                         gg->group_name = NULL;
 148                 }
 149         }
 150 }
 151
 152 /*
 153  * Can sleep, I guess
 154  */
 155 bool
 156 genl_unregister_family(const char *family_name)
 157 {
 158         bool found = false;
 159
 160         GENL_LOCK();
 161         struct genl_family *gf = find_family(family_name);
 162
 163         if (gf != NULL) {
 164                 nlctrl_notify(gf, CTRL_CMD_DELFAMILY);
 165                 found = true;
 166                 unregister_groups(gf);
 167                 /* TODO: zero pointer first */
 168                 free_family(gf);
 169                 bzero(gf, sizeof(*gf));
 170         }
 171         GENL_UNLOCK();
 172
 173         return (found);
 174 }
 175
 176 bool
 177 genl_register_cmds(const char *family_name, const struct genl_cmd *cmds, int count)
 178 {
 179         GENL_LOCK();
 180         struct genl_family *gf = find_family(family_name);
 181         if (gf == NULL) {
 182                 GENL_UNLOCK();
 183                 return (false);
 184         }
 185
 186         int cmd_size = gf->family_cmd_size;
 187
 188         for (int i = 0; i < count; i++) {
 189                 MPASS(cmds[i].cmd_cb != NULL);
 190                 if (cmds[i].cmd_num >= cmd_size)
 191                         cmd_size = cmds[i].cmd_num + 1;
 192         }
 193
 194         if (cmd_size > gf->family_cmd_size) {
 195                 /* need to realloc */
 196                 size_t sz = cmd_size * sizeof(struct genl_cmd);
 197                 void *data = malloc(sz, M_NETLINK, M_WAITOK | M_ZERO);
 198
 199                 memcpy(data, gf->family_cmds, gf->family_cmd_size * sizeof(struct genl_cmd));
 200                 void *old_data = gf->family_cmds;
 201                 gf->family_cmds = data;
 202                 gf->family_cmd_size = cmd_size;
 203                 free(old_data, M_NETLINK);
 204         }
 205
 206         for (int i = 0; i < count; i++) {
 207                 const struct genl_cmd *cmd = &cmds[i];
 208                 MPASS(gf->family_cmds[cmd->cmd_num].cmd_cb == NULL);
 209                 gf->family_cmds[cmd->cmd_num] = cmds[i];
 210                 NL_LOG(LOG_DEBUG2, "Adding cmd %s(%d) to family %s",
 211                     cmd->cmd_name, cmd->cmd_num, gf->family_name);
 212         }
 213         GENL_UNLOCK();
 214         return (true);
 215 }
 216
 217 static struct genl_group *
 218 find_group(const struct genl_family *gf, const char *group_name)
 219 {
 220         for (int i = 0; i < MAX_GROUPS; i++) {
 221                 struct genl_group *gg = &groups[i];
 222                 if (gg->group_family == gf && !strcmp(gg->group_name, group_name))
 223                         return (gg);
 224         }
 225         return (NULL);
 226 }
 227
 228 uint32_t
 229 genl_register_group(const char *family_name, const char *group_name)
 230 {
 231         uint32_t group_id = 0;
 232
 233         MPASS(family_name != NULL);
 234         MPASS(group_name != NULL);
 235
 236         GENL_LOCK();
 237         struct genl_family *gf = find_family(family_name);
 238
 239         if (gf == NULL || find_group(gf, group_name) != NULL) {
 240                 GENL_UNLOCK();
 241                 return (0);
 242         }
 243
 244         for (int i = 0; i < MAX_GROUPS; i++) {
 245                 struct genl_group *gg = &groups[i];
 246                 if (gg->group_family == NULL) {
 247                         gf->family_num_groups++;
 248                         gg->group_family = gf;
 249                         gg->group_name = group_name;
 250                         group_id = i + MIN_GROUP_NUM;
 251                         break;
 252                 }
 253         }
 254         GENL_UNLOCK();
 255
 256         return (group_id);
 257 }
 258
 259 /*
 260  * Handler called by netlink subsystem when matching netlink message is received
 261  */
 262 static int
 263 genl_handle_message(struct nlmsghdr *hdr, struct nl_pstate *npt)
 264 {
 265         struct nlpcb *nlp = npt->nlp;
 266         int error = 0;
 267
 268         int family_id = (int)hdr->nlmsg_type - GENL_MIN_ID;
 269
 270         if (__predict_false(family_id < 0 || family_id >= MAX_FAMILIES)) {
 271                 NLP_LOG(LOG_DEBUG, nlp, "invalid message type: %d", hdr->nlmsg_type);
 272                 return (ENOTSUP);
 273         }
 274
 275         if (__predict_false(hdr->nlmsg_len < sizeof(hdr) + GENL_HDRLEN)) {
 276                 NLP_LOG(LOG_DEBUG, nlp, "invalid message size: %d", hdr->nlmsg_len);
 277                 return (EINVAL);
 278         }
 279
 280         struct genl_family *gf = &families[family_id];
 281
 282         struct genlmsghdr *ghdr = (struct genlmsghdr *)(hdr + 1);
 283
 284         if (ghdr->cmd >= gf->family_cmd_size || gf->family_cmds[ghdr->cmd].cmd_cb == NULL) {
 285                 NLP_LOG(LOG_DEBUG, nlp, "family %s: invalid cmd %d",
 286                     gf->family_name, ghdr->cmd);
 287                 return (ENOTSUP);
 288         }
 289
 290         struct genl_cmd *cmd = &gf->family_cmds[ghdr->cmd];
 291
 292         if (cmd->cmd_priv != 0 && !nlp_has_priv(nlp, cmd->cmd_priv)) {
 293                 NLP_LOG(LOG_DEBUG, nlp, "family %s: cmd %d priv_check() failed",
 294                     gf->family_name, ghdr->cmd);
 295                 return (EPERM);
 296         }
 297
 298         NLP_LOG(LOG_DEBUG2, nlp, "received family %s cmd %s(%d) len %d",
 299             gf->family_name, cmd->cmd_name, ghdr->cmd, hdr->nlmsg_len);
 300
 301         error = cmd->cmd_cb(hdr, npt);
 302
 303         return (error);
 304 }
 305
 306 static uint32_t
 307 get_cmd_flags(const struct genl_cmd *cmd)
 308 {
 309         uint32_t flags = cmd->cmd_flags;
 310         if (cmd->cmd_priv != 0)
 311                 flags |= GENL_ADMIN_PERM;
 312         return (flags);
 313 }
 314
 315 static int
 316 dump_family(struct nlmsghdr *hdr, struct genlmsghdr *ghdr,
 317     const struct genl_family *gf, struct nl_writer *nw)
 318 {
 319         if (!nlmsg_reply(nw, hdr, sizeof(struct genlmsghdr)))
 320                 goto enomem;
 321
 322         struct genlmsghdr *ghdr_new = nlmsg_reserve_object(nw, struct genlmsghdr);
 323         ghdr_new->cmd = ghdr->cmd;
 324         ghdr_new->version = gf->family_version;
 325         ghdr_new->reserved = 0;
 326
 327         nlattr_add_string(nw, CTRL_ATTR_FAMILY_NAME, gf->family_name);
 328         nlattr_add_u16(nw, CTRL_ATTR_FAMILY_ID, gf->family_id);
 329         nlattr_add_u32(nw, CTRL_ATTR_VERSION, gf->family_version);
 330         nlattr_add_u32(nw, CTRL_ATTR_HDRSIZE, gf->family_hdrsize);
 331         nlattr_add_u32(nw, CTRL_ATTR_MAXATTR, gf->family_attr_max);
 332
 333         if (gf->family_cmd_size > 0) {
 334                 int off = nlattr_add_nested(nw, CTRL_ATTR_OPS);
 335                 if (off == 0)
 336                         goto enomem;
 337                 for (int i = 0, cnt=0; i < gf->family_cmd_size; i++) {
 338                         struct genl_cmd *cmd = &gf->family_cmds[i];
 339                         if (cmd->cmd_cb == NULL)
 340                                 continue;
 341                         int cmd_off = nlattr_add_nested(nw, ++cnt);
 342                         if (cmd_off == 0)
 343                                 goto enomem;
 344
 345                         nlattr_add_u32(nw, CTRL_ATTR_OP_ID, cmd->cmd_num);
 346                         nlattr_add_u32(nw, CTRL_ATTR_OP_FLAGS, get_cmd_flags(cmd));
 347                         nlattr_set_len(nw, cmd_off);
 348                 }
 349                 nlattr_set_len(nw, off);
 350         }
 351         if (gf->family_num_groups > 0) {
 352                 int off = nlattr_add_nested(nw, CTRL_ATTR_MCAST_GROUPS);
 353                 if (off == 0)
 354                         goto enomem;
 355                 for (int i = 0, cnt = 0; i < MAX_GROUPS; i++) {
 356                         struct genl_group *gg = &groups[i];
 357                         if (gg->group_family != gf)
 358                                 continue;
 359
 360                         int cmd_off = nlattr_add_nested(nw, ++cnt);
 361                         if (cmd_off == 0)
 362                                 goto enomem;
 363                         nlattr_add_u32(nw, CTRL_ATTR_MCAST_GRP_ID, i + MIN_GROUP_NUM);
 364                         nlattr_add_string(nw, CTRL_ATTR_MCAST_GRP_NAME, gg->group_name);
 365                         nlattr_set_len(nw, cmd_off);
 366                 }
 367                 nlattr_set_len(nw, off);
 368         }
 369         if (nlmsg_end(nw))
 370                 return (0);
 371 enomem:
 372         NL_LOG(LOG_DEBUG, "unable to dump family %s state (ENOMEM)", gf->family_name);
 373         nlmsg_abort(nw);
 374         return (ENOMEM);
 375 }
 376
 377
 378 /* Declare ourself as a user */
 379 #define CTRL_FAMILY_NAME        "nlctrl"
 380
 381 static uint32_t ctrl_family_id;
 382 static uint32_t ctrl_group_id;
 383
 384 struct nl_parsed_family {
 385         uint32_t        family_id;
 386         char            *family_name;
 387         uint8_t         version;
 388 };
 389
 390 #define _IN(_field)     offsetof(struct genlmsghdr, _field)
 391 #define _OUT(_field)    offsetof(struct nl_parsed_family, _field)
 392 static const struct nlfield_parser nlf_p_generic[] = {
 393         { .off_in = _IN(version), .off_out = _OUT(version), .cb = nlf_get_u8 },
 394 };
 395
 396 static struct nlattr_parser nla_p_generic[] = {
 397         { .type = CTRL_ATTR_FAMILY_ID , .off = _OUT(family_id), .cb = nlattr_get_uint16 },
 398         { .type = CTRL_ATTR_FAMILY_NAME , .off = _OUT(family_name), .cb = nlattr_get_string },
 399 };
 400 #undef _IN
 401 #undef _OUT
 402 NL_DECLARE_PARSER(genl_parser, struct genlmsghdr, nlf_p_generic, nla_p_generic);
 403
 404 static bool
 405 match_family(const struct genl_family *gf, const struct nl_parsed_family *attrs)
 406 {
 407         if (gf->family_name == NULL)
 408                 return (false);
 409         if (attrs->family_id != 0 && attrs->family_id != gf->family_id)
 410                 return (false);
 411         if (attrs->family_name != NULL && strcmp(attrs->family_name, gf->family_name))
 412                 return (false);
 413         return (true);
 414 }
 415
 416 static int
 417 nlctrl_handle_getfamily(struct nlmsghdr *hdr, struct nl_pstate *npt)
 418 {
 419         int error = 0;
 420
 421         struct nl_parsed_family attrs = {};
 422         error = nl_parse_nlmsg(hdr, &genl_parser, npt, &attrs);
 423         if (error != 0)
 424                 return (error);
 425
 426         struct genlmsghdr ghdr = {
 427                 .cmd = CTRL_CMD_NEWFAMILY,
 428         };
 429
 430         if (attrs.family_id != 0 || attrs.family_name != NULL) {
 431                 /* Resolve request */
 432                 for (int i = 0; i < MAX_FAMILIES; i++) {
 433                         struct genl_family *gf = &families[i];
 434                         if (match_family(gf, &attrs)) {
 435                                 error = dump_family(hdr, &ghdr, gf, npt->nw);
 436                                 return (error);
 437                         }
 438                 }
 439                 return (ENOENT);
 440         }
 441
 442         hdr->nlmsg_flags = hdr->nlmsg_flags | NLM_F_MULTI;
 443         for (int i = 0; i < MAX_FAMILIES; i++) {
 444                 struct genl_family *gf = &families[i];
 445                 if (match_family(gf, &attrs)) {
 446                         error = dump_family(hdr, &ghdr, gf, npt->nw);
 447                         if (error != 0)
 448                                 break;
 449                 }
 450         }
 451
 452         if (!nlmsg_end_dump(npt->nw, error, hdr)) {
 453                 NL_LOG(LOG_DEBUG, "Unable to finalize the dump");
 454                 return (ENOMEM);
 455         }
 456
 457         return (error);
 458 }
 459
 460 static void
 461 nlctrl_notify(const struct genl_family *gf, int cmd)
 462 {
 463         struct nlmsghdr hdr = {.nlmsg_type = NETLINK_GENERIC };
 464         struct genlmsghdr ghdr = { .cmd = cmd };
 465         struct nl_writer nw = {};
 466
 467         if (nlmsg_get_group_writer(&nw, NLMSG_SMALL, NETLINK_GENERIC, ctrl_group_id)) {
 468                 dump_family(&hdr, &ghdr, gf, &nw);
 469                 nlmsg_flush(&nw);
 470                 return;
 471         }
 472         NL_LOG(LOG_DEBUG, "error allocating group writer");
 473 }
 474
 475 static const struct genl_cmd nlctrl_cmds[] = {
 476         {
 477                 .cmd_num = CTRL_CMD_GETFAMILY,
 478                 .cmd_name = "GETFAMILY",
 479                 .cmd_cb = nlctrl_handle_getfamily,
 480                 .cmd_flags = GENL_CMD_CAP_DO | GENL_CMD_CAP_DUMP | GENL_CMD_CAP_HASPOL,
 481         },
 482 };
 483
 484 static void
 485 genl_nlctrl_init(void)
 486 {
 487         ctrl_family_id = genl_register_family(CTRL_FAMILY_NAME, 0, 2, CTRL_ATTR_MAX);
 488         genl_register_cmds(CTRL_FAMILY_NAME, nlctrl_cmds, NL_ARRAY_LEN(nlctrl_cmds));
 489         ctrl_group_id = genl_register_group(CTRL_FAMILY_NAME, "notify");
 490 }
 491
 492 static void
 493 genl_nlctrl_destroy(void)
 494 {
 495         genl_unregister_family(CTRL_FAMILY_NAME);
 496 }
 497
 498 static const struct nlhdr_parser *all_parsers[] = { &genl_parser };
 499
 500 static void
 501 genl_load(void *u __unused)
 502 {
 503         GENL_LOCK_INIT();
 504         NL_VERIFY_PARSERS(all_parsers);
 505         netlink_register_proto(NETLINK_GENERIC, "NETLINK_GENERIC", genl_handle_message);
 506         genl_nlctrl_init();
 507 }
 508 SYSINIT(genl_load, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, genl_load, NULL);
 509
 510 static void
 511 genl_unload(void *u __unused)
 512 {
 513         genl_nlctrl_destroy();
 514         GENL_LOCK_DESTROY();
 515         NET_EPOCH_WAIT();
 516 }
 517 SYSUNINIT(genl_unload, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, genl_unload, NULL);