linux/include/linux/netlink.h
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   1#ifndef __LINUX_NETLINK_H
   2#define __LINUX_NETLINK_H
   3
   4
   5#include <linux/capability.h>
   6#include <linux/skbuff.h>
   7#include <linux/export.h>
   8#include <net/scm.h>
   9#include <uapi/linux/netlink.h>
  10
  11struct net;
  12
  13static inline struct nlmsghdr *nlmsg_hdr(const struct sk_buff *skb)
  14{
  15        return (struct nlmsghdr *)skb->data;
  16}
  17
  18enum netlink_skb_flags {
  19        NETLINK_SKB_MMAPED      = 0x1,  /* Packet data is mmaped */
  20        NETLINK_SKB_TX          = 0x2,  /* Packet was sent by userspace */
  21        NETLINK_SKB_DELIVERED   = 0x4,  /* Packet was delivered */
  22        NETLINK_SKB_DST         = 0x8,  /* Dst set in sendto or sendmsg */
  23};
  24
  25struct netlink_skb_parms {
  26        struct scm_creds        creds;          /* Skb credentials      */
  27        __u32                   portid;
  28        __u32                   dst_group;
  29        __u32                   flags;
  30        struct sock             *sk;
  31        bool                    nsid_is_set;
  32        int                     nsid;
  33};
  34
  35#define NETLINK_CB(skb)         (*(struct netlink_skb_parms*)&((skb)->cb))
  36#define NETLINK_CREDS(skb)      (&NETLINK_CB((skb)).creds)
  37
  38
  39extern void netlink_table_grab(void);
  40extern void netlink_table_ungrab(void);
  41
  42#define NL_CFG_F_NONROOT_RECV   (1 << 0)
  43#define NL_CFG_F_NONROOT_SEND   (1 << 1)
  44
  45/* optional Netlink kernel configuration parameters */
  46struct netlink_kernel_cfg {
  47        unsigned int    groups;
  48        unsigned int    flags;
  49        void            (*input)(struct sk_buff *skb);
  50        struct mutex    *cb_mutex;
  51        int             (*bind)(int group);
  52        void            (*unbind)(int group);
  53        bool            (*compare)(struct net *net, struct sock *sk);
  54};
  55
  56extern struct sock *__netlink_kernel_create(struct net *net, int unit,
  57                                            struct module *module,
  58                                            struct netlink_kernel_cfg *cfg);
  59static inline struct sock *
  60netlink_kernel_create(struct net *net, int unit, struct netlink_kernel_cfg *cfg)
  61{
  62        return __netlink_kernel_create(net, unit, THIS_MODULE, cfg);
  63}
  64
  65/* RHEL: Specific implementation of NL_SET_ERR_MSG* macros. Due to absence of
  66 * ext-ack support in RHEL7 the macros don't pass the error message to caller
  67 * and instead of this they simply put the message to the system log.
  68 * To avoid flooding of the log macro pr_debug() is used and the error messages
  69 * can be enabled or disabled via dynamic_debug in sysfs.
  70 */
  71#define NL_SET_ERR_MSG(unused, msg) do {                \
  72        static const char __msg[] = msg;                \
  73        pr_debug("%s\n", __msg);                        \
  74} while(0)
  75
  76#define NL_SET_ERR_MSG_MOD(unused, msg) NL_SET_ERR_MSG(unused, msg)
  77
  78extern void netlink_kernel_release(struct sock *sk);
  79extern int __netlink_change_ngroups(struct sock *sk, unsigned int groups);
  80extern int netlink_change_ngroups(struct sock *sk, unsigned int groups);
  81extern void __netlink_clear_multicast_users(struct sock *sk, unsigned int group);
  82extern void netlink_clear_multicast_users(struct sock *sk, unsigned int group);
  83extern void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err);
  84extern int netlink_has_listeners(struct sock *sk, unsigned int group);
  85extern struct sk_buff *netlink_alloc_skb(struct sock *ssk, unsigned int size,
  86                                         u32 dst_portid, gfp_t gfp_mask);
  87extern int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 portid, int nonblock);
  88extern int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 portid,
  89                             __u32 group, gfp_t allocation);
  90extern int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb,
  91        __u32 portid, __u32 group, gfp_t allocation,
  92        int (*filter)(struct sock *dsk, struct sk_buff *skb, void *data),
  93        void *filter_data);
  94extern int netlink_set_err(struct sock *ssk, __u32 portid, __u32 group, int code);
  95extern int netlink_register_notifier(struct notifier_block *nb);
  96extern int netlink_unregister_notifier(struct notifier_block *nb);
  97
  98/* finegrained unicast helpers: */
  99struct sock *netlink_getsockbyfilp(struct file *filp);
 100int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
 101                      long *timeo, struct sock *ssk);
 102void netlink_detachskb(struct sock *sk, struct sk_buff *skb);
 103int netlink_sendskb(struct sock *sk, struct sk_buff *skb);
 104
 105static inline struct sk_buff *
 106netlink_skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
 107{
 108        struct sk_buff *nskb;
 109
 110        nskb = skb_clone(skb, gfp_mask);
 111        if (!nskb)
 112                return NULL;
 113
 114        /* This is a large skb, set destructor callback to release head */
 115        if (is_vmalloc_addr(skb->head))
 116                nskb->destructor = skb->destructor;
 117
 118        return nskb;
 119}
 120
 121/*
 122 *      skb should fit one page. This choice is good for headerless malloc.
 123 *      But we should limit to 8K so that userspace does not have to
 124 *      use enormous buffer sizes on recvmsg() calls just to avoid
 125 *      MSG_TRUNC when PAGE_SIZE is very large.
 126 */
 127#if PAGE_SIZE < 8192UL
 128#define NLMSG_GOODSIZE  SKB_WITH_OVERHEAD(PAGE_SIZE)
 129#else
 130#define NLMSG_GOODSIZE  SKB_WITH_OVERHEAD(8192UL)
 131#endif
 132
 133#define NLMSG_DEFAULT_SIZE (NLMSG_GOODSIZE - NLMSG_HDRLEN)
 134
 135
 136struct netlink_callback {
 137        struct sk_buff          *skb;
 138        const struct nlmsghdr   *nlh;
 139        int                     (*dump)(struct sk_buff * skb,
 140                                        struct netlink_callback *cb);
 141        int                     (*done)(struct netlink_callback *cb);
 142        void                    *data;
 143        /* the module that dump function belong to */
 144        struct module           *module;
 145        u16                     family;
 146        u16                     min_dump_alloc;
 147        unsigned int            prev_seq, seq;
 148        long                    args[6];
 149};
 150
 151struct netlink_notify {
 152        struct net *net;
 153        int portid;
 154        int protocol;
 155};
 156
 157struct nlmsghdr *
 158__nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags);
 159
 160struct netlink_dump_control {
 161        int (*dump)(struct sk_buff *skb, struct netlink_callback *);
 162        int (*done)(struct netlink_callback *);
 163        void *data;
 164        struct module *module;
 165        u16 min_dump_alloc;
 166};
 167
 168extern int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
 169                                const struct nlmsghdr *nlh,
 170                                struct netlink_dump_control *control);
 171static inline int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
 172                                     const struct nlmsghdr *nlh,
 173                                     struct netlink_dump_control *control)
 174{
 175        if (!control->module)
 176                control->module = THIS_MODULE;
 177
 178        return __netlink_dump_start(ssk, skb, nlh, control);
 179}
 180
 181struct netlink_tap {
 182        struct net_device *dev;
 183        struct module *module;
 184        struct list_head list;
 185};
 186
 187extern int netlink_add_tap(struct netlink_tap *nt);
 188extern int __netlink_remove_tap(struct netlink_tap *nt);
 189extern int netlink_remove_tap(struct netlink_tap *nt);
 190
 191bool __netlink_ns_capable(const struct netlink_skb_parms *nsp,
 192                          struct user_namespace *ns, int cap);
 193bool netlink_ns_capable(const struct sk_buff *skb,
 194                        struct user_namespace *ns, int cap);
 195bool netlink_capable(const struct sk_buff *skb, int cap);
 196bool netlink_net_capable(const struct sk_buff *skb, int cap);
 197
 198#endif  /* __LINUX_NETLINK_H */
 199
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