xref: /openbmc/linux/net/core/sysctl_net_core.c (revision 8bdc2a19) 
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 	int ret;
238 
239 	ret = proc_dointvec(table, write, buffer, lenp, ppos);
240 	if (ret != 0)
241 		return ret;
242 
243 	dev_rx_weight = weight_p * dev_weight_rx_bias;
244 	dev_tx_weight = weight_p * dev_weight_tx_bias;
245 
246 	return ret;
247 }
248 
249 static int proc_do_rss_key(struct ctl_table *table, int write,
250 			   void *buffer, size_t *lenp, loff_t *ppos)
251 {
252 	struct ctl_table fake_table;
253 	char buf[NETDEV_RSS_KEY_LEN * 3];
254 
255 	snprintf(buf, sizeof(buf), "%*phC", NETDEV_RSS_KEY_LEN, netdev_rss_key);
256 	fake_table.data = buf;
257 	fake_table.maxlen = sizeof(buf);
258 	return proc_dostring(&fake_table, write, buffer, lenp, ppos);
259 }
260 
261 #ifdef CONFIG_BPF_JIT
262 static int proc_dointvec_minmax_bpf_enable(struct ctl_table *table, int write,
263 					   void *buffer, size_t *lenp,
264 					   loff_t *ppos)
265 {
266 	int ret, jit_enable = *(int *)table->data;
267 	int min = *(int *)table->extra1;
268 	int max = *(int *)table->extra2;
269 	struct ctl_table tmp = *table;
270 
271 	if (write && !capable(CAP_SYS_ADMIN))
272 		return -EPERM;
273 
274 	tmp.data = &jit_enable;
275 	ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
276 	if (write && !ret) {
277 		if (jit_enable < 2 ||
278 		    (jit_enable == 2 && bpf_dump_raw_ok(current_cred()))) {
279 			*(int *)table->data = jit_enable;
280 			if (jit_enable == 2)
281 				pr_warn("bpf_jit_enable = 2 was set! NEVER use this in production, only for JIT debugging!\n");
282 		} else {
283 			ret = -EPERM;
284 		}
285 	}
286 
287 	if (write && ret && min == max)
288 		pr_info_once("CONFIG_BPF_JIT_ALWAYS_ON is enabled, bpf_jit_enable is permanently set to 1.\n");
289 
290 	return ret;
291 }
292 
293 # ifdef CONFIG_HAVE_EBPF_JIT
294 static int
295 proc_dointvec_minmax_bpf_restricted(struct ctl_table *table, int write,
296 				    void *buffer, size_t *lenp, loff_t *ppos)
297 {
298 	if (!capable(CAP_SYS_ADMIN))
299 		return -EPERM;
300 
301 	return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
302 }
303 # endif /* CONFIG_HAVE_EBPF_JIT */
304 
305 static int
306 proc_dolongvec_minmax_bpf_restricted(struct ctl_table *table, int write,
307 				     void *buffer, size_t *lenp, loff_t *ppos)
308 {
309 	if (!capable(CAP_SYS_ADMIN))
310 		return -EPERM;
311 
312 	return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
313 }
314 #endif
315 
316 static struct ctl_table net_core_table[] = {
317 	{
318 		.procname	= "wmem_max",
319 		.data		= &sysctl_wmem_max,
320 		.maxlen		= sizeof(int),
321 		.mode		= 0644,
322 		.proc_handler	= proc_dointvec_minmax,
323 		.extra1		= &min_sndbuf,
324 	},
325 	{
326 		.procname	= "rmem_max",
327 		.data		= &sysctl_rmem_max,
328 		.maxlen		= sizeof(int),
329 		.mode		= 0644,
330 		.proc_handler	= proc_dointvec_minmax,
331 		.extra1		= &min_rcvbuf,
332 	},
333 	{
334 		.procname	= "wmem_default",
335 		.data		= &sysctl_wmem_default,
336 		.maxlen		= sizeof(int),
337 		.mode		= 0644,
338 		.proc_handler	= proc_dointvec_minmax,
339 		.extra1		= &min_sndbuf,
340 	},
341 	{
342 		.procname	= "rmem_default",
343 		.data		= &sysctl_rmem_default,
344 		.maxlen		= sizeof(int),
345 		.mode		= 0644,
346 		.proc_handler	= proc_dointvec_minmax,
347 		.extra1		= &min_rcvbuf,
348 	},
349 	{
350 		.procname	= "dev_weight",
351 		.data		= &weight_p,
352 		.maxlen		= sizeof(int),
353 		.mode		= 0644,
354 		.proc_handler	= proc_do_dev_weight,
355 	},
356 	{
357 		.procname	= "dev_weight_rx_bias",
358 		.data		= &dev_weight_rx_bias,
359 		.maxlen		= sizeof(int),
360 		.mode		= 0644,
361 		.proc_handler	= proc_do_dev_weight,
362 	},
363 	{
364 		.procname	= "dev_weight_tx_bias",
365 		.data		= &dev_weight_tx_bias,
366 		.maxlen		= sizeof(int),
367 		.mode		= 0644,
368 		.proc_handler	= proc_do_dev_weight,
369 	},
370 	{
371 		.procname	= "netdev_max_backlog",
372 		.data		= &netdev_max_backlog,
373 		.maxlen		= sizeof(int),
374 		.mode		= 0644,
375 		.proc_handler	= proc_dointvec
376 	},
377 	{
378 		.procname	= "netdev_rss_key",
379 		.data		= &netdev_rss_key,
380 		.maxlen		= sizeof(int),
381 		.mode		= 0444,
382 		.proc_handler	= proc_do_rss_key,
383 	},
384 #ifdef CONFIG_BPF_JIT
385 	{
386 		.procname	= "bpf_jit_enable",
387 		.data		= &bpf_jit_enable,
388 		.maxlen		= sizeof(int),
389 		.mode		= 0644,
390 		.proc_handler	= proc_dointvec_minmax_bpf_enable,
391 # ifdef CONFIG_BPF_JIT_ALWAYS_ON
392 		.extra1		= SYSCTL_ONE,
393 		.extra2		= SYSCTL_ONE,
394 # else
395 		.extra1		= SYSCTL_ZERO,
396 		.extra2		= SYSCTL_TWO,
397 # endif
398 	},
399 # ifdef CONFIG_HAVE_EBPF_JIT
400 	{
401 		.procname	= "bpf_jit_harden",
402 		.data		= &bpf_jit_harden,
403 		.maxlen		= sizeof(int),
404 		.mode		= 0600,
405 		.proc_handler	= proc_dointvec_minmax_bpf_restricted,
406 		.extra1		= SYSCTL_ZERO,
407 		.extra2		= SYSCTL_TWO,
408 	},
409 	{
410 		.procname	= "bpf_jit_kallsyms",
411 		.data		= &bpf_jit_kallsyms,
412 		.maxlen		= sizeof(int),
413 		.mode		= 0600,
414 		.proc_handler	= proc_dointvec_minmax_bpf_restricted,
415 		.extra1		= SYSCTL_ZERO,
416 		.extra2		= SYSCTL_ONE,
417 	},
418 # endif
419 	{
420 		.procname	= "bpf_jit_limit",
421 		.data		= &bpf_jit_limit,
422 		.maxlen		= sizeof(long),
423 		.mode		= 0600,
424 		.proc_handler	= proc_dolongvec_minmax_bpf_restricted,
425 		.extra1		= SYSCTL_LONG_ONE,
426 		.extra2		= &bpf_jit_limit_max,
427 	},
428 #endif
429 	{
430 		.procname	= "netdev_tstamp_prequeue",
431 		.data		= &netdev_tstamp_prequeue,
432 		.maxlen		= sizeof(int),
433 		.mode		= 0644,
434 		.proc_handler	= proc_dointvec
435 	},
436 	{
437 		.procname	= "message_cost",
438 		.data		= &net_ratelimit_state.interval,
439 		.maxlen		= sizeof(int),
440 		.mode		= 0644,
441 		.proc_handler	= proc_dointvec_jiffies,
442 	},
443 	{
444 		.procname	= "message_burst",
445 		.data		= &net_ratelimit_state.burst,
446 		.maxlen		= sizeof(int),
447 		.mode		= 0644,
448 		.proc_handler	= proc_dointvec,
449 	},
450 	{
451 		.procname	= "optmem_max",
452 		.data		= &sysctl_optmem_max,
453 		.maxlen		= sizeof(int),
454 		.mode		= 0644,
455 		.proc_handler	= proc_dointvec
456 	},
457 	{
458 		.procname	= "tstamp_allow_data",
459 		.data		= &sysctl_tstamp_allow_data,
460 		.maxlen		= sizeof(int),
461 		.mode		= 0644,
462 		.proc_handler	= proc_dointvec_minmax,
463 		.extra1		= SYSCTL_ZERO,
464 		.extra2		= SYSCTL_ONE
465 	},
466 #ifdef CONFIG_RPS
467 	{
468 		.procname	= "rps_sock_flow_entries",
469 		.maxlen		= sizeof(int),
470 		.mode		= 0644,
471 		.proc_handler	= rps_sock_flow_sysctl
472 	},
473 #endif
474 #ifdef CONFIG_NET_FLOW_LIMIT
475 	{
476 		.procname	= "flow_limit_cpu_bitmap",
477 		.mode		= 0644,
478 		.proc_handler	= flow_limit_cpu_sysctl
479 	},
480 	{
481 		.procname	= "flow_limit_table_len",
482 		.data		= &netdev_flow_limit_table_len,
483 		.maxlen		= sizeof(int),
484 		.mode		= 0644,
485 		.proc_handler	= flow_limit_table_len_sysctl
486 	},
487 #endif /* CONFIG_NET_FLOW_LIMIT */
488 #ifdef CONFIG_NET_RX_BUSY_POLL
489 	{
490 		.procname	= "busy_poll",
491 		.data		= &sysctl_net_busy_poll,
492 		.maxlen		= sizeof(unsigned int),
493 		.mode		= 0644,
494 		.proc_handler	= proc_dointvec_minmax,
495 		.extra1		= SYSCTL_ZERO,
496 	},
497 	{
498 		.procname	= "busy_read",
499 		.data		= &sysctl_net_busy_read,
500 		.maxlen		= sizeof(unsigned int),
501 		.mode		= 0644,
502 		.proc_handler	= proc_dointvec_minmax,
503 		.extra1		= SYSCTL_ZERO,
504 	},
505 #endif
506 #ifdef CONFIG_NET_SCHED
507 	{
508 		.procname	= "default_qdisc",
509 		.mode		= 0644,
510 		.maxlen		= IFNAMSIZ,
511 		.proc_handler	= set_default_qdisc
512 	},
513 #endif
514 	{
515 		.procname	= "netdev_budget",
516 		.data		= &netdev_budget,
517 		.maxlen		= sizeof(int),
518 		.mode		= 0644,
519 		.proc_handler	= proc_dointvec
520 	},
521 	{
522 		.procname	= "warnings",
523 		.data		= &net_msg_warn,
524 		.maxlen		= sizeof(int),
525 		.mode		= 0644,
526 		.proc_handler	= proc_dointvec
527 	},
528 	{
529 		.procname	= "max_skb_frags",
530 		.data		= &sysctl_max_skb_frags,
531 		.maxlen		= sizeof(int),
532 		.mode		= 0644,
533 		.proc_handler	= proc_dointvec_minmax,
534 		.extra1		= SYSCTL_ONE,
535 		.extra2		= &max_skb_frags,
536 	},
537 	{
538 		.procname	= "netdev_budget_usecs",
539 		.data		= &netdev_budget_usecs,
540 		.maxlen		= sizeof(unsigned int),
541 		.mode		= 0644,
542 		.proc_handler	= proc_dointvec_minmax,
543 		.extra1		= SYSCTL_ZERO,
544 	},
545 	{
546 		.procname	= "fb_tunnels_only_for_init_net",
547 		.data		= &sysctl_fb_tunnels_only_for_init_net,
548 		.maxlen		= sizeof(int),
549 		.mode		= 0644,
550 		.proc_handler	= proc_dointvec_minmax,
551 		.extra1		= SYSCTL_ZERO,
552 		.extra2		= SYSCTL_TWO,
553 	},
554 	{
555 		.procname	= "devconf_inherit_init_net",
556 		.data		= &sysctl_devconf_inherit_init_net,
557 		.maxlen		= sizeof(int),
558 		.mode		= 0644,
559 		.proc_handler	= proc_dointvec_minmax,
560 		.extra1		= SYSCTL_ZERO,
561 		.extra2		= SYSCTL_THREE,
562 	},
563 	{
564 		.procname	= "high_order_alloc_disable",
565 		.data		= &net_high_order_alloc_disable_key.key,
566 		.maxlen         = sizeof(net_high_order_alloc_disable_key),
567 		.mode		= 0644,
568 		.proc_handler	= proc_do_static_key,
569 	},
570 	{
571 		.procname	= "gro_normal_batch",
572 		.data		= &gro_normal_batch,
573 		.maxlen		= sizeof(unsigned int),
574 		.mode		= 0644,
575 		.proc_handler	= proc_dointvec_minmax,
576 		.extra1		= SYSCTL_ONE,
577 	},
578 	{
579 		.procname	= "netdev_unregister_timeout_secs",
580 		.data		= &netdev_unregister_timeout_secs,
581 		.maxlen		= sizeof(unsigned int),
582 		.mode		= 0644,
583 		.proc_handler	= proc_dointvec_minmax,
584 		.extra1		= SYSCTL_ONE,
585 		.extra2		= &int_3600,
586 	},
587 	{
588 		.procname	= "skb_defer_max",
589 		.data		= &sysctl_skb_defer_max,
590 		.maxlen		= sizeof(unsigned int),
591 		.mode		= 0644,
592 		.proc_handler	= proc_dointvec_minmax,
593 		.extra1		= SYSCTL_ZERO,
594 	},
595 	{ }
596 };
597 
598 static struct ctl_table netns_core_table[] = {
599 	{
600 		.procname	= "somaxconn",
601 		.data		= &init_net.core.sysctl_somaxconn,
602 		.maxlen		= sizeof(int),
603 		.mode		= 0644,
604 		.extra1		= SYSCTL_ZERO,
605 		.proc_handler	= proc_dointvec_minmax
606 	},
607 	{
608 		.procname	= "txrehash",
609 		.data		= &init_net.core.sysctl_txrehash,
610 		.maxlen		= sizeof(u8),
611 		.mode		= 0644,
612 		.extra1		= SYSCTL_ZERO,
613 		.extra2		= SYSCTL_ONE,
614 		.proc_handler	= proc_dou8vec_minmax,
615 	},
616 	{ }
617 };
618 
619 static int __init fb_tunnels_only_for_init_net_sysctl_setup(char *str)
620 {
621 	/* fallback tunnels for initns only */
622 	if (!strncmp(str, "initns", 6))
623 		sysctl_fb_tunnels_only_for_init_net = 1;
624 	/* no fallback tunnels anywhere */
625 	else if (!strncmp(str, "none", 4))
626 		sysctl_fb_tunnels_only_for_init_net = 2;
627 
628 	return 1;
629 }
630 __setup("fb_tunnels=", fb_tunnels_only_for_init_net_sysctl_setup);
631 
632 static __net_init int sysctl_core_net_init(struct net *net)
633 {
634 	struct ctl_table *tbl, *tmp;
635 
636 	tbl = netns_core_table;
637 	if (!net_eq(net, &init_net)) {
638 		tbl = kmemdup(tbl, sizeof(netns_core_table), GFP_KERNEL);
639 		if (tbl == NULL)
640 			goto err_dup;
641 
642 		for (tmp = tbl; tmp->procname; tmp++)
643 			tmp->data += (char *)net - (char *)&init_net;
644 
645 		/* Don't export any sysctls to unprivileged users */
646 		if (net->user_ns != &init_user_ns) {
647 			tbl[0].procname = NULL;
648 		}
649 	}
650 
651 	net->core.sysctl_hdr = register_net_sysctl(net, "net/core", tbl);
652 	if (net->core.sysctl_hdr == NULL)
653 		goto err_reg;
654 
655 	return 0;
656 
657 err_reg:
658 	if (tbl != netns_core_table)
659 		kfree(tbl);
660 err_dup:
661 	return -ENOMEM;
662 }
663 
664 static __net_exit void sysctl_core_net_exit(struct net *net)
665 {
666 	struct ctl_table *tbl;
667 
668 	tbl = net->core.sysctl_hdr->ctl_table_arg;
669 	unregister_net_sysctl_table(net->core.sysctl_hdr);
670 	BUG_ON(tbl == netns_core_table);
671 	kfree(tbl);
672 }
673 
674 static __net_initdata struct pernet_operations sysctl_core_ops = {
675 	.init = sysctl_core_net_init,
676 	.exit = sysctl_core_net_exit,
677 };
678 
679 static __init int sysctl_core_init(void)
680 {
681 	register_net_sysctl(&init_net, "net/core", net_core_table);
682 	return register_pernet_subsys(&sysctl_core_ops);
683 }
684 
685 fs_initcall(sysctl_core_init);
686