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)(struct net *net, int group);
  52        void            (*unbind)(struct net *net, 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/* this can be increased when necessary - don't expose to userland */
  66#define NETLINK_MAX_COOKIE_LEN  20
  67
  68/**
  69 * struct netlink_ext_ack - netlink extended ACK report struct
  70 * @_msg: message string to report - don't access directly, use
  71 *      %NL_SET_ERR_MSG
  72 * @bad_attr: attribute with error
  73 * @cookie: cookie data to return to userspace (for success)
  74 * @cookie_len: actual cookie data length
  75 */
  76struct netlink_ext_ack {
  77        const char *_msg;
  78        const struct nlattr *bad_attr;
  79        u8 cookie[NETLINK_MAX_COOKIE_LEN];
  80        u8 cookie_len;
  81};
  82
  83/* Always use this macro, this allows later putting the
  84 * message into a separate section or such for things
  85 * like translation or listing all possible messages.
  86 * Currently string formatting is not supported (due
  87 * to the lack of an output buffer.)
  88 */
  89#define NL_SET_ERR_MSG(extack, msg) do {                \
  90        static const char __msg[] = (msg);              \
  91        struct netlink_ext_ack *__extack = (extack);    \
  92                                                        \
  93        if (__extack)                                   \
  94                __extack->_msg = __msg;                 \
  95} while (0)
  96
  97#define NL_SET_ERR_MSG_MOD(extack, msg)                 \
  98        NL_SET_ERR_MSG((extack), KBUILD_MODNAME ": " msg)
  99
 100#define NL_SET_BAD_ATTR(extack, attr) do {              \
 101        if ((extack))                                   \
 102                (extack)->bad_attr = (attr);            \
 103} while (0)
 104
 105#define NL_SET_ERR_MSG_ATTR(extack, attr, msg) do {     \
 106        static const char __msg[] = (msg);              \
 107        struct netlink_ext_ack *__extack = (extack);    \
 108                                                        \
 109        if (__extack) {                                 \
 110                __extack->_msg = __msg;                 \
 111                __extack->bad_attr = (attr);            \
 112        }                                               \
 113} while (0)
 114
 115extern void netlink_kernel_release(struct sock *sk);
 116extern int __netlink_change_ngroups(struct sock *sk, unsigned int groups);
 117extern int netlink_change_ngroups(struct sock *sk, unsigned int groups);
 118extern void __netlink_clear_multicast_users(struct sock *sk, unsigned int group);
 119extern void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
 120                        const struct netlink_ext_ack *extack);
 121extern int netlink_has_listeners(struct sock *sk, unsigned int group);
 122
 123extern int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 portid, int nonblock);
 124extern int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 portid,
 125                             __u32 group, gfp_t allocation);
 126extern int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb,
 127        __u32 portid, __u32 group, gfp_t allocation,
 128        int (*filter)(struct sock *dsk, struct sk_buff *skb, void *data),
 129        void *filter_data);
 130extern int netlink_set_err(struct sock *ssk, __u32 portid, __u32 group, int code);
 131extern int netlink_register_notifier(struct notifier_block *nb);
 132extern int netlink_unregister_notifier(struct notifier_block *nb);
 133
 134/* finegrained unicast helpers: */
 135struct sock *netlink_getsockbyfilp(struct file *filp);
 136int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
 137                      long *timeo, struct sock *ssk);
 138void netlink_detachskb(struct sock *sk, struct sk_buff *skb);
 139int netlink_sendskb(struct sock *sk, struct sk_buff *skb);
 140
 141static inline struct sk_buff *
 142netlink_skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
 143{
 144        struct sk_buff *nskb;
 145
 146        nskb = skb_clone(skb, gfp_mask);
 147        if (!nskb)
 148                return NULL;
 149
 150        /* This is a large skb, set destructor callback to release head */
 151        if (is_vmalloc_addr(skb->head))
 152                nskb->destructor = skb->destructor;
 153
 154        return nskb;
 155}
 156
 157/*
 158 *      skb should fit one page. This choice is good for headerless malloc.
 159 *      But we should limit to 8K so that userspace does not have to
 160 *      use enormous buffer sizes on recvmsg() calls just to avoid
 161 *      MSG_TRUNC when PAGE_SIZE is very large.
 162 */
 163#if PAGE_SIZE < 8192UL
 164#define NLMSG_GOODSIZE  SKB_WITH_OVERHEAD(PAGE_SIZE)
 165#else
 166#define NLMSG_GOODSIZE  SKB_WITH_OVERHEAD(8192UL)
 167#endif
 168
 169#define NLMSG_DEFAULT_SIZE (NLMSG_GOODSIZE - NLMSG_HDRLEN)
 170
 171
 172struct netlink_callback {
 173        struct sk_buff          *skb;
 174        const struct nlmsghdr   *nlh;
 175        int                     (*start)(struct netlink_callback *);
 176        int                     (*dump)(struct sk_buff * skb,
 177                                        struct netlink_callback *cb);
 178        int                     (*done)(struct netlink_callback *cb);
 179        void                    *data;
 180        /* the module that dump function belong to */
 181        struct module           *module;
 182        u16                     family;
 183        u16                     min_dump_alloc;
 184        unsigned int            prev_seq, seq;
 185        long                    args[6];
 186};
 187
 188struct netlink_notify {
 189        struct net *net;
 190        u32 portid;
 191        int protocol;
 192};
 193
 194struct nlmsghdr *
 195__nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags);
 196
 197struct netlink_dump_control {
 198        int (*start)(struct netlink_callback *);
 199        int (*dump)(struct sk_buff *skb, struct netlink_callback *);
 200        int (*done)(struct netlink_callback *);
 201        void *data;
 202        struct module *module;
 203        u16 min_dump_alloc;
 204};
 205
 206extern int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
 207                                const struct nlmsghdr *nlh,
 208                                struct netlink_dump_control *control);
 209static inline int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
 210                                     const struct nlmsghdr *nlh,
 211                                     struct netlink_dump_control *control)
 212{
 213        if (!control->module)
 214                control->module = THIS_MODULE;
 215
 216        return __netlink_dump_start(ssk, skb, nlh, control);
 217}
 218
 219struct netlink_tap {
 220        struct net_device *dev;
 221        struct module *module;
 222        struct list_head list;
 223};
 224
 225extern int netlink_add_tap(struct netlink_tap *nt);
 226extern int netlink_remove_tap(struct netlink_tap *nt);
 227
 228bool __netlink_ns_capable(const struct netlink_skb_parms *nsp,
 229                          struct user_namespace *ns, int cap);
 230bool netlink_ns_capable(const struct sk_buff *skb,
 231                        struct user_namespace *ns, int cap);
 232bool netlink_capable(const struct sk_buff *skb, int cap);
 233bool netlink_net_capable(const struct sk_buff *skb, int cap);
 234
 235#endif  /* __LINUX_NETLINK_H */
 236
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