xref: /openbmc/linux/net/core/sysctl_net_core.c (revision 54a611b6) 
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 static long long_max __maybe_unused = LONG_MAX;
33 
34 static int net_msg_warn;	/* Unused, but still a sysctl */
35 
36 int sysctl_fb_tunnels_only_for_init_net __read_mostly = 0;
37 EXPORT_SYMBOL(sysctl_fb_tunnels_only_for_init_net);
38 
39 /* 0 - Keep current behavior:
40  *     IPv4: inherit all current settings from init_net
41  *     IPv6: reset all settings to default
42  * 1 - Both inherit all current settings from init_net
43  * 2 - Both reset all settings to default
44  * 3 - Both inherit all settings from current netns
45  */
46 int sysctl_devconf_inherit_init_net __read_mostly;
47 EXPORT_SYMBOL(sysctl_devconf_inherit_init_net);
48 
49 #ifdef CONFIG_RPS
50 static int rps_sock_flow_sysctl(struct ctl_table *table, int write,
51 				void *buffer, size_t *lenp, loff_t *ppos)
52 {
53 	unsigned int orig_size, size;
54 	int ret, i;
55 	struct ctl_table tmp = {
56 		.data = &size,
57 		.maxlen = sizeof(size),
58 		.mode = table->mode
59 	};
60 	struct rps_sock_flow_table *orig_sock_table, *sock_table;
61 	static DEFINE_MUTEX(sock_flow_mutex);
62 
63 	mutex_lock(&sock_flow_mutex);
64 
65 	orig_sock_table = rcu_dereference_protected(rps_sock_flow_table,
66 					lockdep_is_held(&sock_flow_mutex));
67 	size = orig_size = orig_sock_table ? orig_sock_table->mask + 1 : 0;
68 
69 	ret = proc_dointvec(&tmp, write, buffer, lenp, ppos);
70 
71 	if (write) {
72 		if (size) {
73 			if (size > 1<<29) {
74 				/* Enforce limit to prevent overflow */
75 				mutex_unlock(&sock_flow_mutex);
76 				return -EINVAL;
77 			}
78 			size = roundup_pow_of_two(size);
79 			if (size != orig_size) {
80 				sock_table =
81 				    vmalloc(RPS_SOCK_FLOW_TABLE_SIZE(size));
82 				if (!sock_table) {
83 					mutex_unlock(&sock_flow_mutex);
84 					return -ENOMEM;
85 				}
86 				rps_cpu_mask = roundup_pow_of_two(nr_cpu_ids) - 1;
87 				sock_table->mask = size - 1;
88 			} else
89 				sock_table = orig_sock_table;
90 
91 			for (i = 0; i < size; i++)
92 				sock_table->ents[i] = RPS_NO_CPU;
93 		} else
94 			sock_table = NULL;
95 
96 		if (sock_table != orig_sock_table) {
97 			rcu_assign_pointer(rps_sock_flow_table, sock_table);
98 			if (sock_table) {
99 				static_branch_inc(&rps_needed);
100 				static_branch_inc(&rfs_needed);
101 			}
102 			if (orig_sock_table) {
103 				static_branch_dec(&rps_needed);
104 				static_branch_dec(&rfs_needed);
105 				kvfree_rcu(orig_sock_table);
106 			}
107 		}
108 	}
109 
110 	mutex_unlock(&sock_flow_mutex);
111 
112 	return ret;
113 }
114 #endif /* CONFIG_RPS */
115 
116 #ifdef CONFIG_NET_FLOW_LIMIT
117 static DEFINE_MUTEX(flow_limit_update_mutex);
118 
119 static int flow_limit_cpu_sysctl(struct ctl_table *table, int write,
120 				 void *buffer, size_t *lenp, loff_t *ppos)
121 {
122 	struct sd_flow_limit *cur;
123 	struct softnet_data *sd;
124 	cpumask_var_t mask;
125 	int i, len, ret = 0;
126 
127 	if (!alloc_cpumask_var(&mask, GFP_KERNEL))
128 		return -ENOMEM;
129 
130 	if (write) {
131 		ret = cpumask_parse(buffer, mask);
132 		if (ret)
133 			goto done;
134 
135 		mutex_lock(&flow_limit_update_mutex);
136 		len = sizeof(*cur) + netdev_flow_limit_table_len;
137 		for_each_possible_cpu(i) {
138 			sd = &per_cpu(softnet_data, i);
139 			cur = rcu_dereference_protected(sd->flow_limit,
140 				     lockdep_is_held(&flow_limit_update_mutex));
141 			if (cur && !cpumask_test_cpu(i, mask)) {
142 				RCU_INIT_POINTER(sd->flow_limit, NULL);
143 				kfree_rcu(cur);
144 			} else if (!cur && cpumask_test_cpu(i, mask)) {
145 				cur = kzalloc_node(len, GFP_KERNEL,
146 						   cpu_to_node(i));
147 				if (!cur) {
148 					/* not unwinding previous changes */
149 					ret = -ENOMEM;
150 					goto write_unlock;
151 				}
152 				cur->num_buckets = netdev_flow_limit_table_len;
153 				rcu_assign_pointer(sd->flow_limit, cur);
154 			}
155 		}
156 write_unlock:
157 		mutex_unlock(&flow_limit_update_mutex);
158 	} else {
159 		char kbuf[128];
160 
161 		if (*ppos || !*lenp) {
162 			*lenp = 0;
163 			goto done;
164 		}
165 
166 		cpumask_clear(mask);
167 		rcu_read_lock();
168 		for_each_possible_cpu(i) {
169 			sd = &per_cpu(softnet_data, i);
170 			if (rcu_dereference(sd->flow_limit))
171 				cpumask_set_cpu(i, mask);
172 		}
173 		rcu_read_unlock();
174 
175 		len = min(sizeof(kbuf) - 1, *lenp);
176 		len = scnprintf(kbuf, len, "%*pb", cpumask_pr_args(mask));
177 		if (!len) {
178 			*lenp = 0;
179 			goto done;
180 		}
181 		if (len < *lenp)
182 			kbuf[len++] = '\n';
183 		memcpy(buffer, kbuf, len);
184 		*lenp = len;
185 		*ppos += len;
186 	}
187 
188 done:
189 	free_cpumask_var(mask);
190 	return ret;
191 }
192 
193 static int flow_limit_table_len_sysctl(struct ctl_table *table, int write,
194 				       void *buffer, size_t *lenp, loff_t *ppos)
195 {
196 	unsigned int old, *ptr;
197 	int ret;
198 
199 	mutex_lock(&flow_limit_update_mutex);
200 
201 	ptr = table->data;
202 	old = *ptr;
203 	ret = proc_dointvec(table, write, buffer, lenp, ppos);
204 	if (!ret && write && !is_power_of_2(*ptr)) {
205 		*ptr = old;
206 		ret = -EINVAL;
207 	}
208 
209 	mutex_unlock(&flow_limit_update_mutex);
210 	return ret;
211 }
212 #endif /* CONFIG_NET_FLOW_LIMIT */
213 
214 #ifdef CONFIG_NET_SCHED
215 static int set_default_qdisc(struct ctl_table *table, int write,
216 			     void *buffer, size_t *lenp, loff_t *ppos)
217 {
218 	char id[IFNAMSIZ];
219 	struct ctl_table tbl = {
220 		.data = id,
221 		.maxlen = IFNAMSIZ,
222 	};
223 	int ret;
224 
225 	qdisc_get_default(id, IFNAMSIZ);
226 
227 	ret = proc_dostring(&tbl, write, buffer, lenp, ppos);
228 	if (write && ret == 0)
229 		ret = qdisc_set_default(id);
230 	return ret;
231 }
232 #endif
233 
234 static int proc_do_dev_weight(struct ctl_table *table, int write,
235 			   void *buffer, size_t *lenp, loff_t *ppos)
236 {
237 	static DEFINE_MUTEX(dev_weight_mutex);
238 	int ret, weight;
239 
240 	mutex_lock(&dev_weight_mutex);
241 	ret = proc_dointvec(table, write, buffer, lenp, ppos);
242 	if (!ret && write) {
243 		weight = READ_ONCE(weight_p);
244 		WRITE_ONCE(dev_rx_weight, weight * dev_weight_rx_bias);
245 		WRITE_ONCE(dev_tx_weight, weight * dev_weight_tx_bias);
246 	}
247 	mutex_unlock(&dev_weight_mutex);
248 
249 	return ret;
250 }
251 
252 static int proc_do_rss_key(struct ctl_table *table, int write,
253 			   void *buffer, size_t *lenp, loff_t *ppos)
254 {
255 	struct ctl_table fake_table;
256 	char buf[NETDEV_RSS_KEY_LEN * 3];
257 
258 	snprintf(buf, sizeof(buf), "%*phC", NETDEV_RSS_KEY_LEN, netdev_rss_key);
259 	fake_table.data = buf;
260 	fake_table.maxlen = sizeof(buf);
261 	return proc_dostring(&fake_table, write, buffer, lenp, ppos);
262 }
263 
264 #ifdef CONFIG_BPF_JIT
265 static int proc_dointvec_minmax_bpf_enable(struct ctl_table *table, int write,
266 					   void *buffer, size_t *lenp,
267 					   loff_t *ppos)
268 {
269 	int ret, jit_enable = *(int *)table->data;
270 	int min = *(int *)table->extra1;
271 	int max = *(int *)table->extra2;
272 	struct ctl_table tmp = *table;
273 
274 	if (write && !capable(CAP_SYS_ADMIN))
275 		return -EPERM;
276 
277 	tmp.data = &jit_enable;
278 	ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
279 	if (write && !ret) {
280 		if (jit_enable < 2 ||
281 		    (jit_enable == 2 && bpf_dump_raw_ok(current_cred()))) {
282 			*(int *)table->data = jit_enable;
283 			if (jit_enable == 2)
284 				pr_warn("bpf_jit_enable = 2 was set! NEVER use this in production, only for JIT debugging!\n");
285 		} else {
286 			ret = -EPERM;
287 		}
288 	}
289 
290 	if (write && ret && min == max)
291 		pr_info_once("CONFIG_BPF_JIT_ALWAYS_ON is enabled, bpf_jit_enable is permanently set to 1.\n");
292 
293 	return ret;
294 }
295 
296 # ifdef CONFIG_HAVE_EBPF_JIT
297 static int
298 proc_dointvec_minmax_bpf_restricted(struct ctl_table *table, int write,
299 				    void *buffer, size_t *lenp, loff_t *ppos)
300 {
301 	if (!capable(CAP_SYS_ADMIN))
302 		return -EPERM;
303 
304 	return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
305 }
306 # endif /* CONFIG_HAVE_EBPF_JIT */
307 
308 static int
309 proc_dolongvec_minmax_bpf_restricted(struct ctl_table *table, int write,
310 				     void *buffer, size_t *lenp, loff_t *ppos)
311 {
312 	if (!capable(CAP_SYS_ADMIN))
313 		return -EPERM;
314 
315 	return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
316 }
317 #endif
318 
319 static struct ctl_table net_core_table[] = {
320 	{
321 		.procname	= "wmem_max",
322 		.data		= &sysctl_wmem_max,
323 		.maxlen		= sizeof(int),
324 		.mode		= 0644,
325 		.proc_handler	= proc_dointvec_minmax,
326 		.extra1		= &min_sndbuf,
327 	},
328 	{
329 		.procname	= "rmem_max",
330 		.data		= &sysctl_rmem_max,
331 		.maxlen		= sizeof(int),
332 		.mode		= 0644,
333 		.proc_handler	= proc_dointvec_minmax,
334 		.extra1		= &min_rcvbuf,
335 	},
336 	{
337 		.procname	= "wmem_default",
338 		.data		= &sysctl_wmem_default,
339 		.maxlen		= sizeof(int),
340 		.mode		= 0644,
341 		.proc_handler	= proc_dointvec_minmax,
342 		.extra1		= &min_sndbuf,
343 	},
344 	{
345 		.procname	= "rmem_default",
346 		.data		= &sysctl_rmem_default,
347 		.maxlen		= sizeof(int),
348 		.mode		= 0644,
349 		.proc_handler	= proc_dointvec_minmax,
350 		.extra1		= &min_rcvbuf,
351 	},
352 	{
353 		.procname	= "dev_weight",
354 		.data		= &weight_p,
355 		.maxlen		= sizeof(int),
356 		.mode		= 0644,
357 		.proc_handler	= proc_do_dev_weight,
358 	},
359 	{
360 		.procname	= "dev_weight_rx_bias",
361 		.data		= &dev_weight_rx_bias,
362 		.maxlen		= sizeof(int),
363 		.mode		= 0644,
364 		.proc_handler	= proc_do_dev_weight,
365 	},
366 	{
367 		.procname	= "dev_weight_tx_bias",
368 		.data		= &dev_weight_tx_bias,
369 		.maxlen		= sizeof(int),
370 		.mode		= 0644,
371 		.proc_handler	= proc_do_dev_weight,
372 	},
373 	{
374 		.procname	= "netdev_max_backlog",
375 		.data		= &netdev_max_backlog,
376 		.maxlen		= sizeof(int),
377 		.mode		= 0644,
378 		.proc_handler	= proc_dointvec
379 	},
380 	{
381 		.procname	= "netdev_rss_key",
382 		.data		= &netdev_rss_key,
383 		.maxlen		= sizeof(int),
384 		.mode		= 0444,
385 		.proc_handler	= proc_do_rss_key,
386 	},
387 #ifdef CONFIG_BPF_JIT
388 	{
389 		.procname	= "bpf_jit_enable",
390 		.data		= &bpf_jit_enable,
391 		.maxlen		= sizeof(int),
392 		.mode		= 0644,
393 		.proc_handler	= proc_dointvec_minmax_bpf_enable,
394 # ifdef CONFIG_BPF_JIT_ALWAYS_ON
395 		.extra1		= SYSCTL_ONE,
396 		.extra2		= SYSCTL_ONE,
397 # else
398 		.extra1		= SYSCTL_ZERO,
399 		.extra2		= SYSCTL_TWO,
400 # endif
401 	},
402 # ifdef CONFIG_HAVE_EBPF_JIT
403 	{
404 		.procname	= "bpf_jit_harden",
405 		.data		= &bpf_jit_harden,
406 		.maxlen		= sizeof(int),
407 		.mode		= 0600,
408 		.proc_handler	= proc_dointvec_minmax_bpf_restricted,
409 		.extra1		= SYSCTL_ZERO,
410 		.extra2		= SYSCTL_TWO,
411 	},
412 	{
413 		.procname	= "bpf_jit_kallsyms",
414 		.data		= &bpf_jit_kallsyms,
415 		.maxlen		= sizeof(int),
416 		.mode		= 0600,
417 		.proc_handler	= proc_dointvec_minmax_bpf_restricted,
418 		.extra1		= SYSCTL_ZERO,
419 		.extra2		= SYSCTL_ONE,
420 	},
421 # endif
422 	{
423 		.procname	= "bpf_jit_limit",
424 		.data		= &bpf_jit_limit,
425 		.maxlen		= sizeof(long),
426 		.mode		= 0600,
427 		.proc_handler	= proc_dolongvec_minmax_bpf_restricted,
428 		.extra1		= SYSCTL_LONG_ONE,
429 		.extra2		= &bpf_jit_limit_max,
430 	},
431 #endif
432 	{
433 		.procname	= "netdev_tstamp_prequeue",
434 		.data		= &netdev_tstamp_prequeue,
435 		.maxlen		= sizeof(int),
436 		.mode		= 0644,
437 		.proc_handler	= proc_dointvec
438 	},
439 	{
440 		.procname	= "message_cost",
441 		.data		= &net_ratelimit_state.interval,
442 		.maxlen		= sizeof(int),
443 		.mode		= 0644,
444 		.proc_handler	= proc_dointvec_jiffies,
445 	},
446 	{
447 		.procname	= "message_burst",
448 		.data		= &net_ratelimit_state.burst,
449 		.maxlen		= sizeof(int),
450 		.mode		= 0644,
451 		.proc_handler	= proc_dointvec,
452 	},
453 	{
454 		.procname	= "optmem_max",
455 		.data		= &sysctl_optmem_max,
456 		.maxlen		= sizeof(int),
457 		.mode		= 0644,
458 		.proc_handler	= proc_dointvec
459 	},
460 	{
461 		.procname	= "tstamp_allow_data",
462 		.data		= &sysctl_tstamp_allow_data,
463 		.maxlen		= sizeof(int),
464 		.mode		= 0644,
465 		.proc_handler	= proc_dointvec_minmax,
466 		.extra1		= SYSCTL_ZERO,
467 		.extra2		= SYSCTL_ONE
468 	},
469 #ifdef CONFIG_RPS
470 	{
471 		.procname	= "rps_sock_flow_entries",
472 		.maxlen		= sizeof(int),
473 		.mode		= 0644,
474 		.proc_handler	= rps_sock_flow_sysctl
475 	},
476 #endif
477 #ifdef CONFIG_NET_FLOW_LIMIT
478 	{
479 		.procname	= "flow_limit_cpu_bitmap",
480 		.mode		= 0644,
481 		.proc_handler	= flow_limit_cpu_sysctl
482 	},
483 	{
484 		.procname	= "flow_limit_table_len",
485 		.data		= &netdev_flow_limit_table_len,
486 		.maxlen		= sizeof(int),
487 		.mode		= 0644,
488 		.proc_handler	= flow_limit_table_len_sysctl
489 	},
490 #endif /* CONFIG_NET_FLOW_LIMIT */
491 #ifdef CONFIG_NET_RX_BUSY_POLL
492 	{
493 		.procname	= "busy_poll",
494 		.data		= &sysctl_net_busy_poll,
495 		.maxlen		= sizeof(unsigned int),
496 		.mode		= 0644,
497 		.proc_handler	= proc_dointvec_minmax,
498 		.extra1		= SYSCTL_ZERO,
499 	},
500 	{
501 		.procname	= "busy_read",
502 		.data		= &sysctl_net_busy_read,
503 		.maxlen		= sizeof(unsigned int),
504 		.mode		= 0644,
505 		.proc_handler	= proc_dointvec_minmax,
506 		.extra1		= SYSCTL_ZERO,
507 	},
508 #endif
509 #ifdef CONFIG_NET_SCHED
510 	{
511 		.procname	= "default_qdisc",
512 		.mode		= 0644,
513 		.maxlen		= IFNAMSIZ,
514 		.proc_handler	= set_default_qdisc
515 	},
516 #endif
517 	{
518 		.procname	= "netdev_budget",
519 		.data		= &netdev_budget,
520 		.maxlen		= sizeof(int),
521 		.mode		= 0644,
522 		.proc_handler	= proc_dointvec
523 	},
524 	{
525 		.procname	= "warnings",
526 		.data		= &net_msg_warn,
527 		.maxlen		= sizeof(int),
528 		.mode		= 0644,
529 		.proc_handler	= proc_dointvec
530 	},
531 	{
532 		.procname	= "max_skb_frags",
533 		.data		= &sysctl_max_skb_frags,
534 		.maxlen		= sizeof(int),
535 		.mode		= 0644,
536 		.proc_handler	= proc_dointvec_minmax,
537 		.extra1		= SYSCTL_ONE,
538 		.extra2		= &max_skb_frags,
539 	},
540 	{
541 		.procname	= "netdev_budget_usecs",
542 		.data		= &netdev_budget_usecs,
543 		.maxlen		= sizeof(unsigned int),
544 		.mode		= 0644,
545 		.proc_handler	= proc_dointvec_minmax,
546 		.extra1		= SYSCTL_ZERO,
547 	},
548 	{
549 		.procname	= "fb_tunnels_only_for_init_net",
550 		.data		= &sysctl_fb_tunnels_only_for_init_net,
551 		.maxlen		= sizeof(int),
552 		.mode		= 0644,
553 		.proc_handler	= proc_dointvec_minmax,
554 		.extra1		= SYSCTL_ZERO,
555 		.extra2		= SYSCTL_TWO,
556 	},
557 	{
558 		.procname	= "devconf_inherit_init_net",
559 		.data		= &sysctl_devconf_inherit_init_net,
560 		.maxlen		= sizeof(int),
561 		.mode		= 0644,
562 		.proc_handler	= proc_dointvec_minmax,
563 		.extra1		= SYSCTL_ZERO,
564 		.extra2		= SYSCTL_THREE,
565 	},
566 	{
567 		.procname	= "high_order_alloc_disable",
568 		.data		= &net_high_order_alloc_disable_key.key,
569 		.maxlen         = sizeof(net_high_order_alloc_disable_key),
570 		.mode		= 0644,
571 		.proc_handler	= proc_do_static_key,
572 	},
573 	{
574 		.procname	= "gro_normal_batch",
575 		.data		= &gro_normal_batch,
576 		.maxlen		= sizeof(unsigned int),
577 		.mode		= 0644,
578 		.proc_handler	= proc_dointvec_minmax,
579 		.extra1		= SYSCTL_ONE,
580 	},
581 	{
582 		.procname	= "netdev_unregister_timeout_secs",
583 		.data		= &netdev_unregister_timeout_secs,
584 		.maxlen		= sizeof(unsigned int),
585 		.mode		= 0644,
586 		.proc_handler	= proc_dointvec_minmax,
587 		.extra1		= SYSCTL_ONE,
588 		.extra2		= &int_3600,
589 	},
590 	{
591 		.procname	= "skb_defer_max",
592 		.data		= &sysctl_skb_defer_max,
593 		.maxlen		= sizeof(unsigned int),
594 		.mode		= 0644,
595 		.proc_handler	= proc_dointvec_minmax,
596 		.extra1		= SYSCTL_ZERO,
597 	},
598 	{ }
599 };
600 
601 static struct ctl_table netns_core_table[] = {
602 	{
603 		.procname	= "somaxconn",
604 		.data		= &init_net.core.sysctl_somaxconn,
605 		.maxlen		= sizeof(int),
606 		.mode		= 0644,
607 		.extra1		= SYSCTL_ZERO,
608 		.proc_handler	= proc_dointvec_minmax
609 	},
610 	{
611 		.procname	= "txrehash",
612 		.data		= &init_net.core.sysctl_txrehash,
613 		.maxlen		= sizeof(u8),
614 		.mode		= 0644,
615 		.extra1		= SYSCTL_ZERO,
616 		.extra2		= SYSCTL_ONE,
617 		.proc_handler	= proc_dou8vec_minmax,
618 	},
619 	{ }
620 };
621 
622 static int __init fb_tunnels_only_for_init_net_sysctl_setup(char *str)
623 {
624 	/* fallback tunnels for initns only */
625 	if (!strncmp(str, "initns", 6))
626 		sysctl_fb_tunnels_only_for_init_net = 1;
627 	/* no fallback tunnels anywhere */
628 	else if (!strncmp(str, "none", 4))
629 		sysctl_fb_tunnels_only_for_init_net = 2;
630 
631 	return 1;
632 }
633 __setup("fb_tunnels=", fb_tunnels_only_for_init_net_sysctl_setup);
634 
635 static __net_init int sysctl_core_net_init(struct net *net)
636 {
637 	struct ctl_table *tbl, *tmp;
638 
639 	tbl = netns_core_table;
640 	if (!net_eq(net, &init_net)) {
641 		tbl = kmemdup(tbl, sizeof(netns_core_table), GFP_KERNEL);
642 		if (tbl == NULL)
643 			goto err_dup;
644 
645 		for (tmp = tbl; tmp->procname; tmp++)
646 			tmp->data += (char *)net - (char *)&init_net;
647 
648 		/* Don't export any sysctls to unprivileged users */
649 		if (net->user_ns != &init_user_ns) {
650 			tbl[0].procname = NULL;
651 		}
652 	}
653 
654 	net->core.sysctl_hdr = register_net_sysctl(net, "net/core", tbl);
655 	if (net->core.sysctl_hdr == NULL)
656 		goto err_reg;
657 
658 	return 0;
659 
660 err_reg:
661 	if (tbl != netns_core_table)
662 		kfree(tbl);
663 err_dup:
664 	return -ENOMEM;
665 }
666 
667 static __net_exit void sysctl_core_net_exit(struct net *net)
668 {
669 	struct ctl_table *tbl;
670 
671 	tbl = net->core.sysctl_hdr->ctl_table_arg;
672 	unregister_net_sysctl_table(net->core.sysctl_hdr);
673 	BUG_ON(tbl == netns_core_table);
674 	kfree(tbl);
675 }
676 
677 static __net_initdata struct pernet_operations sysctl_core_ops = {
678 	.init = sysctl_core_net_init,
679 	.exit = sysctl_core_net_exit,
680 };
681 
682 static __init int sysctl_core_init(void)
683 {
684 	register_net_sysctl(&init_net, "net/core", net_core_table);
685 	return register_pernet_subsys(&sysctl_core_ops);
686 }
687 
688 fs_initcall(sysctl_core_init);
689