sysctl_net.c 2.97 KB
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/* -*- linux-c -*-
 * sysctl_net.c: sysctl interface to net subsystem.
 *
 * Begun April 1, 1996, Mike Shaver.
 * Added /proc/sys/net directories for each protocol family. [MS]
 *
 * Revision 1.2  1996/05/08  20:24:40  shaver
 * Added bits for NET_BRIDGE and the NET_IPV4_ARP stuff and
 * NET_IPV4_IP_FORWARD.
 *
 *
 */

#include <linux/mm.h>
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#include <linux/export.h>
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#include <linux/sysctl.h>
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#include <linux/nsproxy.h>
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#include <net/sock.h>

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#ifdef CONFIG_INET
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#include <net/ip.h>
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#endif

#ifdef CONFIG_NET
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#include <linux/if_ether.h>
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#endif

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static struct ctl_table_set *
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net_ctl_header_lookup(struct ctl_table_root *root)
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{
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	return &current->nsproxy->net_ns->sysctls;
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}

static int is_seen(struct ctl_table_set *set)
{
	return &current->nsproxy->net_ns->sysctls == set;
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}

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/* Return standard mode bits for table entry. */
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static int net_ctl_permissions(struct ctl_table_header *head,
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			       struct ctl_table *table)
{
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	struct net *net = container_of(head->set, struct net, sysctls);

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	/* Allow network administrator to have same access as root. */
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	if (ns_capable_noaudit(net->user_ns, CAP_NET_ADMIN)) {
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		int mode = (table->mode >> 6) & 7;
		return (mode << 6) | (mode << 3) | mode;
	}
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	return table->mode;
}

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static void net_ctl_set_ownership(struct ctl_table_header *head,
				  struct ctl_table *table,
				  kuid_t *uid, kgid_t *gid)
{
	struct net *net = container_of(head->set, struct net, sysctls);
	kuid_t ns_root_uid;
	kgid_t ns_root_gid;

	ns_root_uid = make_kuid(net->user_ns, 0);
	if (uid_valid(ns_root_uid))
		*uid = ns_root_uid;

	ns_root_gid = make_kgid(net->user_ns, 0);
	if (gid_valid(ns_root_gid))
		*gid = ns_root_gid;
}

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static struct ctl_table_root net_sysctl_root = {
	.lookup = net_ctl_header_lookup,
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	.permissions = net_ctl_permissions,
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	.set_ownership = net_ctl_set_ownership,
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};

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static int __net_init sysctl_net_init(struct net *net)
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{
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	setup_sysctl_set(&net->sysctls, &net_sysctl_root, is_seen);
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	return 0;
}

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static void __net_exit sysctl_net_exit(struct net *net)
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{
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	retire_sysctl_set(&net->sysctls);
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}

static struct pernet_operations sysctl_pernet_ops = {
	.init = sysctl_net_init,
	.exit = sysctl_net_exit,
};

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static struct ctl_table_header *net_header;
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__init int net_sysctl_init(void)
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{
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	static struct ctl_table empty[1];
	int ret = -ENOMEM;
	/* Avoid limitations in the sysctl implementation by
	 * registering "/proc/sys/net" as an empty directory not in a
	 * network namespace.
	 */
	net_header = register_sysctl("net", empty);
	if (!net_header)
		goto out;
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	ret = register_pernet_subsys(&sysctl_pernet_ops);
	if (ret)
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		goto out1;
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out:
	return ret;
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out1:
	unregister_sysctl_table(net_header);
	net_header = NULL;
	goto out;
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}

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struct ctl_table_header *register_net_sysctl(struct net *net,
	const char *path, struct ctl_table *table)
{
	return __register_sysctl_table(&net->sysctls, path, table);
}
EXPORT_SYMBOL_GPL(register_net_sysctl);

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void unregister_net_sysctl_table(struct ctl_table_header *header)
{
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	unregister_sysctl_table(header);
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}
EXPORT_SYMBOL_GPL(unregister_net_sysctl_table);