netlink.h

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#ifndef __LINUX_NETLINK_H
#define __LINUX_NETLINK_H


#include <linux/capability.h>
#include <linux/skbuff.h>
#include <linux/export.h>
#include <net/scm.h>
#include <uapi/linux/netlink.h>

struct net;

static inline struct nlmsghdr *nlmsg_hdr(const struct sk_buff *skb)
{
    return (struct nlmsghdr *)skb->data;
}

struct netlink_skb_parms {
    struct scm_creds    creds;      /* Skb credentials  */
    __u32           portid;
    __u32           dst_group;
    struct sock     *ssk;
};

#define NETLINK_CB(skb)     (*(struct netlink_skb_parms*)&((skb)->cb))
#define NETLINK_CREDS(skb)  (&NETLINK_CB((skb)).creds)


extern void netlink_table_grab(void);
extern void netlink_table_ungrab(void);

#define NL_CFG_F_NONROOT_RECV   (1 << 0)
#define NL_CFG_F_NONROOT_SEND   (1 << 1)

/* optional Netlink kernel configuration parameters */
struct netlink_kernel_cfg {
    unsigned int    groups;
    unsigned int    flags;
    void        (*input)(struct sk_buff *skb);
    struct mutex    *cb_mutex;
    void        (*bind)(int group);
};

extern struct sock *__netlink_kernel_create(struct net *net, int unit,
                        struct module *module,
                        struct netlink_kernel_cfg *cfg);
static inline struct sock *
netlink_kernel_create(struct net *net, int unit, struct netlink_kernel_cfg *cfg)
{
    return __netlink_kernel_create(net, unit, THIS_MODULE, cfg);
}

extern void netlink_kernel_release(struct sock *sk);
extern int __netlink_change_ngroups(struct sock *sk, unsigned int groups);
extern int netlink_change_ngroups(struct sock *sk, unsigned int groups);
extern void __netlink_clear_multicast_users(struct sock *sk, unsigned int group);
extern void netlink_clear_multicast_users(struct sock *sk, unsigned int group);
extern void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err);
extern int netlink_has_listeners(struct sock *sk, unsigned int group);
extern int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 portid, int nonblock);
extern int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 portid,
                 __u32 group, gfp_t allocation);
extern int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb,
    __u32 portid, __u32 group, gfp_t allocation,
    int (*filter)(struct sock *dsk, struct sk_buff *skb, void *data),
    void *filter_data);
extern int netlink_set_err(struct sock *ssk, __u32 portid, __u32 group, int code);
extern int netlink_register_notifier(struct notifier_block *nb);
extern int netlink_unregister_notifier(struct notifier_block *nb);

/* finegrained unicast helpers: */
struct sock *netlink_getsockbyfilp(struct file *filp);
int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
              long *timeo, struct sock *ssk);
void netlink_detachskb(struct sock *sk, struct sk_buff *skb);
int netlink_sendskb(struct sock *sk, struct sk_buff *skb);

/*
 *  skb should fit one page. This choice is good for headerless malloc.
 *  But we should limit to 8K so that userspace does not have to
 *  use enormous buffer sizes on recvmsg() calls just to avoid
 *  MSG_TRUNC when PAGE_SIZE is very large.
 */
#if PAGE_SIZE < 8192UL
#define NLMSG_GOODSIZE  SKB_WITH_OVERHEAD(PAGE_SIZE)
#else
#define NLMSG_GOODSIZE  SKB_WITH_OVERHEAD(8192UL)
#endif

#define NLMSG_DEFAULT_SIZE (NLMSG_GOODSIZE - NLMSG_HDRLEN)


struct netlink_callback {
    struct sk_buff      *skb;
    const struct nlmsghdr   *nlh;
    int         (*dump)(struct sk_buff * skb,
                    struct netlink_callback *cb);
    int         (*done)(struct netlink_callback *cb);
    void            *data;
    /* the module that dump function belong to */
    struct module       *module;
    u16         family;
    u16         min_dump_alloc;
    unsigned int        prev_seq, seq;
    long            args[6];
};

struct netlink_notify {
    struct net *net;
    int portid;
    int protocol;
};

struct nlmsghdr *
__nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags);

struct netlink_dump_control {
    int (*dump)(struct sk_buff *skb, struct netlink_callback *);
    int (*done)(struct netlink_callback *);
    void *data;
    struct module *module;
    u16 min_dump_alloc;
};

extern int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
                const struct nlmsghdr *nlh,
                struct netlink_dump_control *control);
static inline int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
                     const struct nlmsghdr *nlh,
                     struct netlink_dump_control *control)
{
    if (!control->module)
        control->module = THIS_MODULE;

    return __netlink_dump_start(ssk, skb, nlh, control);
}

#endif  /* __LINUX_NETLINK_H */