sysctl_net.c

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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>
#include <linux/export.h>
#include <linux/sysctl.h>
#include <linux/nsproxy.h>

#include <net/sock.h>

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

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

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

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

/* Return standard mode bits for table entry. */
static int net_ctl_permissions(struct ctl_table_root *root,
                   struct nsproxy *nsproxy,
                   struct ctl_table *table)
{
    /* Allow network administrator to have same access as root. */
    if (capable(CAP_NET_ADMIN)) {
        int mode = (table->mode >> 6) & 7;
        return (mode << 6) | (mode << 3) | mode;
    }
    return table->mode;
}

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

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

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

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

static struct ctl_table_header *net_header;
__init int net_sysctl_init(void)
{
    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;
    ret = register_pernet_subsys(&sysctl_pernet_ops);
    if (ret)
        goto out;
    register_sysctl_root(&net_sysctl_root);
out:
    return ret;
}

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);

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