include/linux/netlink.h

   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
  11 struct net;
  12
  13 static inline struct nlmsghdr *nlmsg_hdr(const struct sk_buff *skb)
  14 {
  15         return (struct nlmsghdr *)skb->data;
  16 }
  17
  18 enum 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
  25 struct 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
  39 extern void netlink_table_grab(void);
  40 extern 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 */
  46 struct 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
  56 extern struct sock *__netlink_kernel_create(struct net *net, int unit,
  57                                             struct module *module,
  58                                             struct netlink_kernel_cfg *cfg);
  59 static inline struct sock *
  60 netlink_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  */
  76 struct 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
 115 extern void netlink_kernel_release(struct sock *sk);
 116 extern int __netlink_change_ngroups(struct sock *sk, unsigned int groups);
 117 extern int netlink_change_ngroups(struct sock *sk, unsigned int groups);
 118 extern void __netlink_clear_multicast_users(struct sock *sk, unsigned int group);
 119 extern void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
 120                         const struct netlink_ext_ack *extack);
 121 extern int netlink_has_listeners(struct sock *sk, unsigned int group);
 122
 123 extern int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 portid, int nonblock);
 124 extern int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 portid,
 125                              __u32 group, gfp_t allocation);
 126 extern 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);
 130 extern int netlink_set_err(struct sock *ssk, __u32 portid, __u32 group, int code);
 131 extern int netlink_register_notifier(struct notifier_block *nb);
 132 extern int netlink_unregister_notifier(struct notifier_block *nb);
 133
 134 /* finegrained unicast helpers: */
 135 struct sock *netlink_getsockbyfilp(struct file *filp);
 136 int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
 137                       long *timeo, struct sock *ssk);
 138 void netlink_detachskb(struct sock *sk, struct sk_buff *skb);
 139 int netlink_sendskb(struct sock *sk, struct sk_buff *skb);
 140
 141 static inline struct sk_buff *
 142 netlink_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
 172 struct 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
 188 struct netlink_notify {
 189         struct net *net;
 190         u32 portid;
 191         int protocol;
 192 };
 193
 194 struct nlmsghdr *
 195 __nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags);
 196
 197 struct 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
 206 extern int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
 207                                 const struct nlmsghdr *nlh,
 208                                 struct netlink_dump_control *control);
 209 static 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
 219 struct netlink_tap {
 220         struct net_device *dev;
 221         struct module *module;
 222         struct list_head list;
 223 };
 224
 225 extern int netlink_add_tap(struct netlink_tap *nt);
 226 extern int netlink_remove_tap(struct netlink_tap *nt);
 227
 228 bool __netlink_ns_capable(const struct netlink_skb_parms *nsp,
 229                           struct user_namespace *ns, int cap);
 230 bool netlink_ns_capable(const struct sk_buff *skb,
 231                         struct user_namespace *ns, int cap);
 232 bool netlink_capable(const struct sk_buff *skb, int cap);
 233 bool netlink_net_capable(const struct sk_buff *skb, int cap);
 234
 235 #endif  /* __LINUX_NETLINK_H */