net/core/sysctl_net_core.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* -*- linux-c -*-
   3  * sysctl_net_core.c: sysctl interface to net core subsystem.
   4  *
   5  * Begun April 1, 1996, Mike Shaver.
   6  * Added /proc/sys/net/core directory entry (empty =) ). [MS]
   7  */
   8
   9 #include <linux/filter.h>
  10 #include <linux/mm.h>
  11 #include <linux/sysctl.h>
  12 #include <linux/module.h>
  13 #include <linux/socket.h>
  14 #include <linux/netdevice.h>
  15 #include <linux/ratelimit.h>
  16 #include <linux/vmalloc.h>
  17 #include <linux/init.h>
  18 #include <linux/slab.h>
  19
  20 #include <net/ip.h>
  21 #include <net/sock.h>
  22 #include <net/net_ratelimit.h>
  23 #include <net/busy_poll.h>
  24 #include <net/pkt_sched.h>
  25
  26 #include "dev.h"
  27
  28 static int int_3600 = 3600;
  29 static int min_sndbuf = SOCK_MIN_SNDBUF;
  30 static int min_rcvbuf = SOCK_MIN_RCVBUF;
  31 static int max_skb_frags = MAX_SKB_FRAGS;
  32
  33 static int net_msg_warn;        /* Unused, but still a sysctl */
  34
  35 int sysctl_fb_tunnels_only_for_init_net __read_mostly = 0;
  36 EXPORT_SYMBOL(sysctl_fb_tunnels_only_for_init_net);
  37
  38 /* 0 - Keep current behavior:
  39  *     IPv4: inherit all current settings from init_net
  40  *     IPv6: reset all settings to default
  41  * 1 - Both inherit all current settings from init_net
  42  * 2 - Both reset all settings to default
  43  * 3 - Both inherit all settings from current netns
  44  */
  45 int sysctl_devconf_inherit_init_net __read_mostly;
  46 EXPORT_SYMBOL(sysctl_devconf_inherit_init_net);
  47
  48 #ifdef CONFIG_RPS
  49 static int rps_sock_flow_sysctl(struct ctl_table *table, int write,
  50                                 void *buffer, size_t *lenp, loff_t *ppos)
  51 {
  52         unsigned int orig_size, size;
  53         int ret, i;
  54         struct ctl_table tmp = {
  55                 .data = &size,
  56                 .maxlen = sizeof(size),
  57                 .mode = table->mode
  58         };
  59         struct rps_sock_flow_table *orig_sock_table, *sock_table;
  60         static DEFINE_MUTEX(sock_flow_mutex);
  61
  62         mutex_lock(&sock_flow_mutex);
  63
  64         orig_sock_table = rcu_dereference_protected(rps_sock_flow_table,
  65                                         lockdep_is_held(&sock_flow_mutex));
  66         size = orig_size = orig_sock_table ? orig_sock_table->mask + 1 : 0;
  67
  68         ret = proc_dointvec(&tmp, write, buffer, lenp, ppos);
  69
  70         if (write) {
  71                 if (size) {
  72                         if (size > 1<<29) {
  73                                 /* Enforce limit to prevent overflow */
  74                                 mutex_unlock(&sock_flow_mutex);
  75                                 return -EINVAL;
  76                         }
  77                         size = roundup_pow_of_two(size);
  78                         if (size != orig_size) {
  79                                 sock_table =
  80                                     vmalloc(RPS_SOCK_FLOW_TABLE_SIZE(size));
  81                                 if (!sock_table) {
  82                                         mutex_unlock(&sock_flow_mutex);
  83                                         return -ENOMEM;
  84                                 }
  85                                 rps_cpu_mask = roundup_pow_of_two(nr_cpu_ids) - 1;
  86                                 sock_table->mask = size - 1;
  87                         } else
  88                                 sock_table = orig_sock_table;
  89
  90                         for (i = 0; i < size; i++)
  91                                 sock_table->ents[i] = RPS_NO_CPU;
  92                 } else
  93                         sock_table = NULL;
  94
  95                 if (sock_table != orig_sock_table) {
  96                         rcu_assign_pointer(rps_sock_flow_table, sock_table);
  97                         if (sock_table) {
  98                                 static_branch_inc(&rps_needed);
  99                                 static_branch_inc(&rfs_needed);
 100                         }
 101                         if (orig_sock_table) {
 102                                 static_branch_dec(&rps_needed);
 103                                 static_branch_dec(&rfs_needed);
 104                                 kvfree_rcu(orig_sock_table);
 105                         }
 106                 }
 107         }
 108
 109         mutex_unlock(&sock_flow_mutex);
 110
 111         return ret;
 112 }
 113 #endif /* CONFIG_RPS */
 114
 115 #ifdef CONFIG_NET_FLOW_LIMIT
 116 static DEFINE_MUTEX(flow_limit_update_mutex);
 117
 118 static int flow_limit_cpu_sysctl(struct ctl_table *table, int write,
 119                                  void *buffer, size_t *lenp, loff_t *ppos)
 120 {
 121         struct sd_flow_limit *cur;
 122         struct softnet_data *sd;
 123         cpumask_var_t mask;
 124         int i, len, ret = 0;
 125
 126         if (!alloc_cpumask_var(&mask, GFP_KERNEL))
 127                 return -ENOMEM;
 128
 129         if (write) {
 130                 ret = cpumask_parse(buffer, mask);
 131                 if (ret)
 132                         goto done;
 133
 134                 mutex_lock(&flow_limit_update_mutex);
 135                 len = sizeof(*cur) + netdev_flow_limit_table_len;
 136                 for_each_possible_cpu(i) {
 137                         sd = &per_cpu(softnet_data, i);
 138                         cur = rcu_dereference_protected(sd->flow_limit,
 139                                      lockdep_is_held(&flow_limit_update_mutex));
 140                         if (cur && !cpumask_test_cpu(i, mask)) {
 141                                 RCU_INIT_POINTER(sd->flow_limit, NULL);
 142                                 kfree_rcu(cur);
 143                         } else if (!cur && cpumask_test_cpu(i, mask)) {
 144                                 cur = kzalloc_node(len, GFP_KERNEL,
 145                                                    cpu_to_node(i));
 146                                 if (!cur) {
 147                                         /* not unwinding previous changes */
 148                                         ret = -ENOMEM;
 149                                         goto write_unlock;
 150                                 }
 151                                 cur->num_buckets = netdev_flow_limit_table_len;
 152                                 rcu_assign_pointer(sd->flow_limit, cur);
 153                         }
 154                 }
 155 write_unlock:
 156                 mutex_unlock(&flow_limit_update_mutex);
 157         } else {
 158                 char kbuf[128];
 159
 160                 if (*ppos || !*lenp) {
 161                         *lenp = 0;
 162                         goto done;
 163                 }
 164
 165                 cpumask_clear(mask);
 166                 rcu_read_lock();
 167                 for_each_possible_cpu(i) {
 168                         sd = &per_cpu(softnet_data, i);
 169                         if (rcu_dereference(sd->flow_limit))
 170                                 cpumask_set_cpu(i, mask);
 171                 }
 172                 rcu_read_unlock();
 173
 174                 len = min(sizeof(kbuf) - 1, *lenp);
 175                 len = scnprintf(kbuf, len, "%*pb", cpumask_pr_args(mask));
 176                 if (!len) {
 177                         *lenp = 0;
 178                         goto done;
 179                 }
 180                 if (len < *lenp)
 181                         kbuf[len++] = '\n';
 182                 memcpy(buffer, kbuf, len);
 183                 *lenp = len;
 184                 *ppos += len;
 185         }
 186
 187 done:
 188         free_cpumask_var(mask);
 189         return ret;
 190 }
 191
 192 static int flow_limit_table_len_sysctl(struct ctl_table *table, int write,
 193                                        void *buffer, size_t *lenp, loff_t *ppos)
 194 {
 195         unsigned int old, *ptr;
 196         int ret;
 197
 198         mutex_lock(&flow_limit_update_mutex);
 199
 200         ptr = table->data;
 201         old = *ptr;
 202         ret = proc_dointvec(table, write, buffer, lenp, ppos);
 203         if (!ret && write && !is_power_of_2(*ptr)) {
 204                 *ptr = old;
 205                 ret = -EINVAL;
 206         }
 207
 208         mutex_unlock(&flow_limit_update_mutex);
 209         return ret;
 210 }
 211 #endif /* CONFIG_NET_FLOW_LIMIT */
 212
 213 #ifdef CONFIG_NET_SCHED
 214 static int set_default_qdisc(struct ctl_table *table, int write,
 215                              void *buffer, size_t *lenp, loff_t *ppos)
 216 {
 217         char id[IFNAMSIZ];
 218         struct ctl_table tbl = {
 219                 .data = id,
 220                 .maxlen = IFNAMSIZ,
 221         };
 222         int ret;
 223
 224         qdisc_get_default(id, IFNAMSIZ);
 225
 226         ret = proc_dostring(&tbl, write, buffer, lenp, ppos);
 227         if (write && ret == 0)
 228                 ret = qdisc_set_default(id);
 229         return ret;
 230 }
 231 #endif
 232
 233 static int proc_do_dev_weight(struct ctl_table *table, int write,
 234                            void *buffer, size_t *lenp, loff_t *ppos)
 235 {
 236         static DEFINE_MUTEX(dev_weight_mutex);
 237         int ret, weight;
 238
 239         mutex_lock(&dev_weight_mutex);
 240         ret = proc_dointvec(table, write, buffer, lenp, ppos);
 241         if (!ret && write) {
 242                 weight = READ_ONCE(weight_p);
 243                 WRITE_ONCE(dev_rx_weight, weight * dev_weight_rx_bias);
 244                 WRITE_ONCE(dev_tx_weight, weight * dev_weight_tx_bias);
 245         }
 246         mutex_unlock(&dev_weight_mutex);
 247
 248         return ret;
 249 }
 250
 251 static int proc_do_rss_key(struct ctl_table *table, int write,
 252                            void *buffer, size_t *lenp, loff_t *ppos)
 253 {
 254         struct ctl_table fake_table;
 255         char buf[NETDEV_RSS_KEY_LEN * 3];
 256
 257         snprintf(buf, sizeof(buf), "%*phC", NETDEV_RSS_KEY_LEN, netdev_rss_key);
 258         fake_table.data = buf;
 259         fake_table.maxlen = sizeof(buf);
 260         return proc_dostring(&fake_table, write, buffer, lenp, ppos);
 261 }
 262
 263 #ifdef CONFIG_BPF_JIT
 264 static int proc_dointvec_minmax_bpf_enable(struct ctl_table *table, int write,
 265                                            void *buffer, size_t *lenp,
 266                                            loff_t *ppos)
 267 {
 268         int ret, jit_enable = *(int *)table->data;
 269         int min = *(int *)table->extra1;
 270         int max = *(int *)table->extra2;
 271         struct ctl_table tmp = *table;
 272
 273         if (write && !capable(CAP_SYS_ADMIN))
 274                 return -EPERM;
 275
 276         tmp.data = &jit_enable;
 277         ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
 278         if (write && !ret) {
 279                 if (jit_enable < 2 ||
 280                     (jit_enable == 2 && bpf_dump_raw_ok(current_cred()))) {
 281                         *(int *)table->data = jit_enable;
 282                         if (jit_enable == 2)
 283                                 pr_warn("bpf_jit_enable = 2 was set! NEVER use this in production, only for JIT debugging!\n");
 284                 } else {
 285                         ret = -EPERM;
 286                 }
 287         }
 288
 289         if (write && ret && min == max)
 290                 pr_info_once("CONFIG_BPF_JIT_ALWAYS_ON is enabled, bpf_jit_enable is permanently set to 1.\n");
 291
 292         return ret;
 293 }
 294
 295 # ifdef CONFIG_HAVE_EBPF_JIT
 296 static int
 297 proc_dointvec_minmax_bpf_restricted(struct ctl_table *table, int write,
 298                                     void *buffer, size_t *lenp, loff_t *ppos)
 299 {
 300         if (!capable(CAP_SYS_ADMIN))
 301                 return -EPERM;
 302
 303         return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
 304 }
 305 # endif /* CONFIG_HAVE_EBPF_JIT */
 306
 307 static int
 308 proc_dolongvec_minmax_bpf_restricted(struct ctl_table *table, int write,
 309                                      void *buffer, size_t *lenp, loff_t *ppos)
 310 {
 311         if (!capable(CAP_SYS_ADMIN))
 312                 return -EPERM;
 313
 314         return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
 315 }
 316 #endif
 317
 318 static struct ctl_table net_core_table[] = {
 319         {
 320                 .procname       = "wmem_max",
 321                 .data           = &sysctl_wmem_max,
 322                 .maxlen         = sizeof(int),
 323                 .mode           = 0644,
 324                 .proc_handler   = proc_dointvec_minmax,
 325                 .extra1         = &min_sndbuf,
 326         },
 327         {
 328                 .procname       = "rmem_max",
 329                 .data           = &sysctl_rmem_max,
 330                 .maxlen         = sizeof(int),
 331                 .mode           = 0644,
 332                 .proc_handler   = proc_dointvec_minmax,
 333                 .extra1         = &min_rcvbuf,
 334         },
 335         {
 336                 .procname       = "wmem_default",
 337                 .data           = &sysctl_wmem_default,
 338                 .maxlen         = sizeof(int),
 339                 .mode           = 0644,
 340                 .proc_handler   = proc_dointvec_minmax,
 341                 .extra1         = &min_sndbuf,
 342         },
 343         {
 344                 .procname       = "rmem_default",
 345                 .data           = &sysctl_rmem_default,
 346                 .maxlen         = sizeof(int),
 347                 .mode           = 0644,
 348                 .proc_handler   = proc_dointvec_minmax,
 349                 .extra1         = &min_rcvbuf,
 350         },
 351         {
 352                 .procname       = "dev_weight",
 353                 .data           = &weight_p,
 354                 .maxlen         = sizeof(int),
 355                 .mode           = 0644,
 356                 .proc_handler   = proc_do_dev_weight,
 357         },
 358         {
 359                 .procname       = "dev_weight_rx_bias",
 360                 .data           = &dev_weight_rx_bias,
 361                 .maxlen         = sizeof(int),
 362                 .mode           = 0644,
 363                 .proc_handler   = proc_do_dev_weight,
 364         },
 365         {
 366                 .procname       = "dev_weight_tx_bias",
 367                 .data           = &dev_weight_tx_bias,
 368                 .maxlen         = sizeof(int),
 369                 .mode           = 0644,
 370                 .proc_handler   = proc_do_dev_weight,
 371         },
 372         {
 373                 .procname       = "netdev_max_backlog",
 374                 .data           = &netdev_max_backlog,
 375                 .maxlen         = sizeof(int),
 376                 .mode           = 0644,
 377                 .proc_handler   = proc_dointvec
 378         },
 379         {
 380                 .procname       = "netdev_rss_key",
 381                 .data           = &netdev_rss_key,
 382                 .maxlen         = sizeof(int),
 383                 .mode           = 0444,
 384                 .proc_handler   = proc_do_rss_key,
 385         },
 386 #ifdef CONFIG_BPF_JIT
 387         {
 388                 .procname       = "bpf_jit_enable",
 389                 .data           = &bpf_jit_enable,
 390                 .maxlen         = sizeof(int),
 391                 .mode           = 0644,
 392                 .proc_handler   = proc_dointvec_minmax_bpf_enable,
 393 # ifdef CONFIG_BPF_JIT_ALWAYS_ON
 394                 .extra1         = SYSCTL_ONE,
 395                 .extra2         = SYSCTL_ONE,
 396 # else
 397                 .extra1         = SYSCTL_ZERO,
 398                 .extra2         = SYSCTL_TWO,
 399 # endif
 400         },
 401 # ifdef CONFIG_HAVE_EBPF_JIT
 402         {
 403                 .procname       = "bpf_jit_harden",
 404                 .data           = &bpf_jit_harden,
 405                 .maxlen         = sizeof(int),
 406                 .mode           = 0600,
 407                 .proc_handler   = proc_dointvec_minmax_bpf_restricted,
 408                 .extra1         = SYSCTL_ZERO,
 409                 .extra2         = SYSCTL_TWO,
 410         },
 411         {
 412                 .procname       = "bpf_jit_kallsyms",
 413                 .data           = &bpf_jit_kallsyms,
 414                 .maxlen         = sizeof(int),
 415                 .mode           = 0600,
 416                 .proc_handler   = proc_dointvec_minmax_bpf_restricted,
 417                 .extra1         = SYSCTL_ZERO,
 418                 .extra2         = SYSCTL_ONE,
 419         },
 420 # endif
 421         {
 422                 .procname       = "bpf_jit_limit",
 423                 .data           = &bpf_jit_limit,
 424                 .maxlen         = sizeof(long),
 425                 .mode           = 0600,
 426                 .proc_handler   = proc_dolongvec_minmax_bpf_restricted,
 427                 .extra1         = SYSCTL_LONG_ONE,
 428                 .extra2         = &bpf_jit_limit_max,
 429         },
 430 #endif
 431         {
 432                 .procname       = "netdev_tstamp_prequeue",
 433                 .data           = &netdev_tstamp_prequeue,
 434                 .maxlen         = sizeof(int),
 435                 .mode           = 0644,
 436                 .proc_handler   = proc_dointvec
 437         },
 438         {
 439                 .procname       = "message_cost",
 440                 .data           = &net_ratelimit_state.interval,
 441                 .maxlen         = sizeof(int),
 442                 .mode           = 0644,
 443                 .proc_handler   = proc_dointvec_jiffies,
 444         },
 445         {
 446                 .procname       = "message_burst",
 447                 .data           = &net_ratelimit_state.burst,
 448                 .maxlen         = sizeof(int),
 449                 .mode           = 0644,
 450                 .proc_handler   = proc_dointvec,
 451         },
 452         {
 453                 .procname       = "optmem_max",
 454                 .data           = &sysctl_optmem_max,
 455                 .maxlen         = sizeof(int),
 456                 .mode           = 0644,
 457                 .proc_handler   = proc_dointvec
 458         },
 459         {
 460                 .procname       = "tstamp_allow_data",
 461                 .data           = &sysctl_tstamp_allow_data,
 462                 .maxlen         = sizeof(int),
 463                 .mode           = 0644,
 464                 .proc_handler   = proc_dointvec_minmax,
 465                 .extra1         = SYSCTL_ZERO,
 466                 .extra2         = SYSCTL_ONE
 467         },
 468 #ifdef CONFIG_RPS
 469         {
 470                 .procname       = "rps_sock_flow_entries",
 471                 .maxlen         = sizeof(int),
 472                 .mode           = 0644,
 473                 .proc_handler   = rps_sock_flow_sysctl
 474         },
 475 #endif
 476 #ifdef CONFIG_NET_FLOW_LIMIT
 477         {
 478                 .procname       = "flow_limit_cpu_bitmap",
 479                 .mode           = 0644,
 480                 .proc_handler   = flow_limit_cpu_sysctl
 481         },
 482         {
 483                 .procname       = "flow_limit_table_len",
 484                 .data           = &netdev_flow_limit_table_len,
 485                 .maxlen         = sizeof(int),
 486                 .mode           = 0644,
 487                 .proc_handler   = flow_limit_table_len_sysctl
 488         },
 489 #endif /* CONFIG_NET_FLOW_LIMIT */
 490 #ifdef CONFIG_NET_RX_BUSY_POLL
 491         {
 492                 .procname       = "busy_poll",
 493                 .data           = &sysctl_net_busy_poll,
 494                 .maxlen         = sizeof(unsigned int),
 495                 .mode           = 0644,
 496                 .proc_handler   = proc_dointvec_minmax,
 497                 .extra1         = SYSCTL_ZERO,
 498         },
 499         {
 500                 .procname       = "busy_read",
 501                 .data           = &sysctl_net_busy_read,
 502                 .maxlen         = sizeof(unsigned int),
 503                 .mode           = 0644,
 504                 .proc_handler   = proc_dointvec_minmax,
 505                 .extra1         = SYSCTL_ZERO,
 506         },
 507 #endif
 508 #ifdef CONFIG_NET_SCHED
 509         {
 510                 .procname       = "default_qdisc",
 511                 .mode           = 0644,
 512                 .maxlen         = IFNAMSIZ,
 513                 .proc_handler   = set_default_qdisc
 514         },
 515 #endif
 516         {
 517                 .procname       = "netdev_budget",
 518                 .data           = &netdev_budget,
 519                 .maxlen         = sizeof(int),
 520                 .mode           = 0644,
 521                 .proc_handler   = proc_dointvec
 522         },
 523         {
 524                 .procname       = "warnings",
 525                 .data           = &net_msg_warn,
 526                 .maxlen         = sizeof(int),
 527                 .mode           = 0644,
 528                 .proc_handler   = proc_dointvec
 529         },
 530         {
 531                 .procname       = "max_skb_frags",
 532                 .data           = &sysctl_max_skb_frags,
 533                 .maxlen         = sizeof(int),
 534                 .mode           = 0644,
 535                 .proc_handler   = proc_dointvec_minmax,
 536                 .extra1         = SYSCTL_ONE,
 537                 .extra2         = &max_skb_frags,
 538         },
 539         {
 540                 .procname       = "netdev_budget_usecs",
 541                 .data           = &netdev_budget_usecs,
 542                 .maxlen         = sizeof(unsigned int),
 543                 .mode           = 0644,
 544                 .proc_handler   = proc_dointvec_minmax,
 545                 .extra1         = SYSCTL_ZERO,
 546         },
 547         {
 548                 .procname       = "fb_tunnels_only_for_init_net",
 549                 .data           = &sysctl_fb_tunnels_only_for_init_net,
 550                 .maxlen         = sizeof(int),
 551                 .mode           = 0644,
 552                 .proc_handler   = proc_dointvec_minmax,
 553                 .extra1         = SYSCTL_ZERO,
 554                 .extra2         = SYSCTL_TWO,
 555         },
 556         {
 557                 .procname       = "devconf_inherit_init_net",
 558                 .data           = &sysctl_devconf_inherit_init_net,
 559                 .maxlen         = sizeof(int),
 560                 .mode           = 0644,
 561                 .proc_handler   = proc_dointvec_minmax,
 562                 .extra1         = SYSCTL_ZERO,
 563                 .extra2         = SYSCTL_THREE,
 564         },
 565         {
 566                 .procname       = "high_order_alloc_disable",
 567                 .data           = &net_high_order_alloc_disable_key.key,
 568                 .maxlen         = sizeof(net_high_order_alloc_disable_key),
 569                 .mode           = 0644,
 570                 .proc_handler   = proc_do_static_key,
 571         },
 572         {
 573                 .procname       = "gro_normal_batch",
 574                 .data           = &gro_normal_batch,
 575                 .maxlen         = sizeof(unsigned int),
 576                 .mode           = 0644,
 577                 .proc_handler   = proc_dointvec_minmax,
 578                 .extra1         = SYSCTL_ONE,
 579         },
 580         {
 581                 .procname       = "netdev_unregister_timeout_secs",
 582                 .data           = &netdev_unregister_timeout_secs,
 583                 .maxlen         = sizeof(unsigned int),
 584                 .mode           = 0644,
 585                 .proc_handler   = proc_dointvec_minmax,
 586                 .extra1         = SYSCTL_ONE,
 587                 .extra2         = &int_3600,
 588         },
 589         {
 590                 .procname       = "skb_defer_max",
 591                 .data           = &sysctl_skb_defer_max,
 592                 .maxlen         = sizeof(unsigned int),
 593                 .mode           = 0644,
 594                 .proc_handler   = proc_dointvec_minmax,
 595                 .extra1         = SYSCTL_ZERO,
 596         },
 597         { }
 598 };
 599
 600 static struct ctl_table netns_core_table[] = {
 601         {
 602                 .procname       = "somaxconn",
 603                 .data           = &init_net.core.sysctl_somaxconn,
 604                 .maxlen         = sizeof(int),
 605                 .mode           = 0644,
 606                 .extra1         = SYSCTL_ZERO,
 607                 .proc_handler   = proc_dointvec_minmax
 608         },
 609         {
 610                 .procname       = "txrehash",
 611                 .data           = &init_net.core.sysctl_txrehash,
 612                 .maxlen         = sizeof(u8),
 613                 .mode           = 0644,
 614                 .extra1         = SYSCTL_ZERO,
 615                 .extra2         = SYSCTL_ONE,
 616                 .proc_handler   = proc_dou8vec_minmax,
 617         },
 618         { }
 619 };
 620
 621 static int __init fb_tunnels_only_for_init_net_sysctl_setup(char *str)
 622 {
 623         /* fallback tunnels for initns only */
 624         if (!strncmp(str, "initns", 6))
 625                 sysctl_fb_tunnels_only_for_init_net = 1;
 626         /* no fallback tunnels anywhere */
 627         else if (!strncmp(str, "none", 4))
 628                 sysctl_fb_tunnels_only_for_init_net = 2;
 629
 630         return 1;
 631 }
 632 __setup("fb_tunnels=", fb_tunnels_only_for_init_net_sysctl_setup);
 633
 634 static __net_init int sysctl_core_net_init(struct net *net)
 635 {
 636         struct ctl_table *tbl, *tmp;
 637
 638         tbl = netns_core_table;
 639         if (!net_eq(net, &init_net)) {
 640                 tbl = kmemdup(tbl, sizeof(netns_core_table), GFP_KERNEL);
 641                 if (tbl == NULL)
 642                         goto err_dup;
 643
 644                 for (tmp = tbl; tmp->procname; tmp++)
 645                         tmp->data += (char *)net - (char *)&init_net;
 646
 647                 /* Don't export any sysctls to unprivileged users */
 648                 if (net->user_ns != &init_user_ns) {
 649                         tbl[0].procname = NULL;
 650                 }
 651         }
 652
 653         net->core.sysctl_hdr = register_net_sysctl(net, "net/core", tbl);
 654         if (net->core.sysctl_hdr == NULL)
 655                 goto err_reg;
 656
 657         return 0;
 658
 659 err_reg:
 660         if (tbl != netns_core_table)
 661                 kfree(tbl);
 662 err_dup:
 663         return -ENOMEM;
 664 }
 665
 666 static __net_exit void sysctl_core_net_exit(struct net *net)
 667 {
 668         struct ctl_table *tbl;
 669
 670         tbl = net->core.sysctl_hdr->ctl_table_arg;
 671         unregister_net_sysctl_table(net->core.sysctl_hdr);
 672         BUG_ON(tbl == netns_core_table);
 673         kfree(tbl);
 674 }
 675
 676 static __net_initdata struct pernet_operations sysctl_core_ops = {
 677         .init = sysctl_core_net_init,
 678         .exit = sysctl_core_net_exit,
 679 };
 680
 681 static __init int sysctl_core_init(void)
 682 {
 683         register_net_sysctl(&init_net, "net/core", net_core_table);
 684         return register_pernet_subsys(&sysctl_core_ops);
 685 }
 686
 687 fs_initcall(sysctl_core_init);