net_namespace.h

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/*
 * Operations on the network namespace
 */
#ifndef __NET_NET_NAMESPACE_H
#define __NET_NET_NAMESPACE_H

#include <linux/atomic.h>
#include <linux/workqueue.h>
#include <linux/list.h>
#include <linux/sysctl.h>

#include <net/netns/core.h>
#include <net/netns/mib.h>
#include <net/netns/unix.h>
#include <net/netns/packet.h>
#include <net/netns/ipv4.h>
#include <net/netns/ipv6.h>
#include <net/netns/sctp.h>
#include <net/netns/dccp.h>
#include <net/netns/x_tables.h>
#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
#include <net/netns/conntrack.h>
#endif
#include <net/netns/xfrm.h>

struct proc_dir_entry;
struct net_device;
struct sock;
struct ctl_table_header;
struct net_generic;
struct sock;
struct netns_ipvs;


#define NETDEV_HASHBITS    8
#define NETDEV_HASHENTRIES (1 << NETDEV_HASHBITS)

struct net {
    atomic_t        passive;    /* To decided when the network
                         * namespace should be freed.
                         */
    atomic_t        count;      /* To decided when the network
                         *  namespace should be shut down.
                         */
#ifdef NETNS_REFCNT_DEBUG
    atomic_t        use_count;  /* To track references we
                         * destroy on demand
                         */
#endif
    spinlock_t      rules_mod_lock;

    struct list_head    list;       /* list of network namespaces */
    struct list_head    cleanup_list;   /* namespaces on death row */
    struct list_head    exit_list;  /* Use only net_mutex */

    struct proc_dir_entry   *proc_net;
    struct proc_dir_entry   *proc_net_stat;

#ifdef CONFIG_SYSCTL
    struct ctl_table_set    sysctls;
#endif

    struct sock         *rtnl;          /* rtnetlink socket */
    struct sock     *genl_sock;

    struct list_head    dev_base_head;
    struct hlist_head   *dev_name_head;
    struct hlist_head   *dev_index_head;
    unsigned int        dev_base_seq;   /* protected by rtnl_mutex */
    int         ifindex;

    /* core fib_rules */
    struct list_head    rules_ops;


    struct net_device       *loopback_dev;          /* The loopback */
    struct netns_core   core;
    struct netns_mib    mib;
    struct netns_packet packet;
    struct netns_unix   unx;
    struct netns_ipv4   ipv4;
#if IS_ENABLED(CONFIG_IPV6)
    struct netns_ipv6   ipv6;
#endif
#if defined(CONFIG_IP_SCTP) || defined(CONFIG_IP_SCTP_MODULE)
    struct netns_sctp   sctp;
#endif
#if defined(CONFIG_IP_DCCP) || defined(CONFIG_IP_DCCP_MODULE)
    struct netns_dccp   dccp;
#endif
#ifdef CONFIG_NETFILTER
    struct netns_xt     xt;
#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
    struct netns_ct     ct;
#endif
#if IS_ENABLED(CONFIG_NF_DEFRAG_IPV6)
    struct netns_nf_frag    nf_frag;
#endif
    struct sock     *nfnl;
    struct sock     *nfnl_stash;
#endif
#ifdef CONFIG_WEXT_CORE
    struct sk_buff_head wext_nlevents;
#endif
    struct net_generic __rcu    *gen;

    /* Note : following structs are cache line aligned */
#ifdef CONFIG_XFRM
    struct netns_xfrm   xfrm;
#endif
    struct netns_ipvs   *ipvs;
    struct sock     *diag_nlsk;
    atomic_t        rt_genid;
};

/*
 * ifindex generation is per-net namespace, and loopback is
 * always the 1st device in ns (see net_dev_init), thus any
 * loopback device should get ifindex 1
 */

#define LOOPBACK_IFINDEX    1

#include <linux/seq_file_net.h>

/* Init's network namespace */
extern struct net init_net;

#ifdef CONFIG_NET
extern struct net *copy_net_ns(unsigned long flags, struct net *net_ns);

#else /* CONFIG_NET */
static inline struct net *copy_net_ns(unsigned long flags, struct net *net_ns)
{
    /* There is nothing to copy so this is a noop */
    return net_ns;
}
#endif /* CONFIG_NET */


extern struct list_head net_namespace_list;

extern struct net *get_net_ns_by_pid(pid_t pid);
extern struct net *get_net_ns_by_fd(int pid);

#ifdef CONFIG_NET_NS
extern void __put_net(struct net *net);

static inline struct net *get_net(struct net *net)
{
    atomic_inc(&net->count);
    return net;
}

static inline struct net *maybe_get_net(struct net *net)
{
    /* Used when we know struct net exists but we
     * aren't guaranteed a previous reference count
     * exists.  If the reference count is zero this
     * function fails and returns NULL.
     */
    if (!atomic_inc_not_zero(&net->count))
        net = NULL;
    return net;
}

static inline void put_net(struct net *net)
{
    if (atomic_dec_and_test(&net->count))
        __put_net(net);
}

static inline
int net_eq(const struct net *net1, const struct net *net2)
{
    return net1 == net2;
}

extern void net_drop_ns(void *);

#else

static inline struct net *get_net(struct net *net)
{
    return net;
}

static inline void put_net(struct net *net)
{
}

static inline struct net *maybe_get_net(struct net *net)
{
    return net;
}

static inline
int net_eq(const struct net *net1, const struct net *net2)
{
    return 1;
}

#define net_drop_ns NULL
#endif


#ifdef NETNS_REFCNT_DEBUG
static inline struct net *hold_net(struct net *net)
{
    if (net)
        atomic_inc(&net->use_count);
    return net;
}

static inline void release_net(struct net *net)
{
    if (net)
        atomic_dec(&net->use_count);
}
#else
static inline struct net *hold_net(struct net *net)
{
    return net;
}

static inline void release_net(struct net *net)
{
}
#endif

#ifdef CONFIG_NET_NS

static inline void write_pnet(struct net **pnet, struct net *net)
{
    *pnet = net;
}

static inline struct net *read_pnet(struct net * const *pnet)
{
    return *pnet;
}

#else

#define write_pnet(pnet, net)   do { (void)(net);} while (0)
#define read_pnet(pnet)     (&init_net)

#endif

#define for_each_net(VAR)               \
    list_for_each_entry(VAR, &net_namespace_list, list)

#define for_each_net_rcu(VAR)               \
    list_for_each_entry_rcu(VAR, &net_namespace_list, list)

#ifdef CONFIG_NET_NS
#define __net_init
#define __net_exit
#define __net_initdata
#define __net_initconst
#else
#define __net_init  __init
#define __net_exit  __exit_refok
#define __net_initdata  __initdata
#define __net_initconst __initconst
#endif

struct pernet_operations {
    struct list_head list;
    int (*init)(struct net *net);
    void (*exit)(struct net *net);
    void (*exit_batch)(struct list_head *net_exit_list);
    int *id;
    size_t size;
};

/*
 * Use these carefully.  If you implement a network device and it
 * needs per network namespace operations use device pernet operations,
 * otherwise use pernet subsys operations.
 *
 * Network interfaces need to be removed from a dying netns _before_
 * subsys notifiers can be called, as most of the network code cleanup
 * (which is done from subsys notifiers) runs with the assumption that
 * dev_remove_pack has been called so no new packets will arrive during
 * and after the cleanup functions have been called.  dev_remove_pack
 * is not per namespace so instead the guarantee of no more packets
 * arriving in a network namespace is provided by ensuring that all
 * network devices and all sockets have left the network namespace
 * before the cleanup methods are called.
 *
 * For the longest time the ipv4 icmp code was registered as a pernet
 * device which caused kernel oops, and panics during network
 * namespace cleanup.   So please don't get this wrong.
 */
extern int register_pernet_subsys(struct pernet_operations *);
extern void unregister_pernet_subsys(struct pernet_operations *);
extern int register_pernet_device(struct pernet_operations *);
extern void unregister_pernet_device(struct pernet_operations *);

struct ctl_table;
struct ctl_table_header;

#ifdef CONFIG_SYSCTL
extern int net_sysctl_init(void);
extern struct ctl_table_header *register_net_sysctl(struct net *net,
    const char *path, struct ctl_table *table);
extern void unregister_net_sysctl_table(struct ctl_table_header *header);
#else
static inline int net_sysctl_init(void) { return 0; }
static inline struct ctl_table_header *register_net_sysctl(struct net *net,
    const char *path, struct ctl_table *table)
{
    return NULL;
}
static inline void unregister_net_sysctl_table(struct ctl_table_header *header)
{
}
#endif

static inline int rt_genid(struct net *net)
{
    return atomic_read(&net->rt_genid);
}

static inline void rt_genid_bump(struct net *net)
{
    atomic_inc(&net->rt_genid);
}

#endif /* __NET_NET_NAMESPACE_H */