482a8524f8
The generic netlink family builds on top of netlink and provides simplifies access for the less demanding netlink users. It solves the problem of protocol numbers running out by introducing a so called controller taking care of id management and name resolving. Generic netlink modules register themself after filling out their id card (struct genl_family), after successful registration the modules are able to register callbacks to command numbers by filling out a struct genl_ops and calling genl_register_op(). The registered callbacks are invoked with attributes parsed making life of simple modules a lot easier. Although generic netlink modules can request static identifiers, it is recommended to use GENL_ID_GENERATE and to let the controller assign a unique identifier to the module. Userspace applications will then ask the controller and lookup the idenfier by the module name. Due to the current multicast implementation of netlink, the number of generic netlink modules is restricted to 1024 to avoid wasting memory for the per socket multiacst subscription bitmask. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
154 lines
4 KiB
C
154 lines
4 KiB
C
#ifndef __NET_GENERIC_NETLINK_H
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#define __NET_GENERIC_NETLINK_H
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#include <linux/genetlink.h>
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#include <net/netlink.h>
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/**
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* struct genl_family - generic netlink family
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* @id: protocol family idenfitier
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* @hdrsize: length of user specific header in bytes
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* @name: name of family
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* @version: protocol version
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* @maxattr: maximum number of attributes supported
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* @attrbuf: buffer to store parsed attributes
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* @ops_list: list of all assigned operations
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* @family_list: family list
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*/
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struct genl_family
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{
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unsigned int id;
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unsigned int hdrsize;
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char name[GENL_NAMSIZ];
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unsigned int version;
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unsigned int maxattr;
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struct module * owner;
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struct nlattr ** attrbuf; /* private */
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struct list_head ops_list; /* private */
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struct list_head family_list; /* private */
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};
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#define GENL_ADMIN_PERM 0x01
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/**
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* struct genl_info - receiving information
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* @snd_seq: sending sequence number
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* @snd_pid: netlink pid of sender
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* @nlhdr: netlink message header
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* @genlhdr: generic netlink message header
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* @userhdr: user specific header
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* @attrs: netlink attributes
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*/
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struct genl_info
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{
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u32 snd_seq;
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u32 snd_pid;
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struct nlmsghdr * nlhdr;
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struct genlmsghdr * genlhdr;
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void * userhdr;
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struct nlattr ** attrs;
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};
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/**
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* struct genl_ops - generic netlink operations
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* @cmd: command identifier
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* @flags: flags
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* @policy: attribute validation policy
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* @doit: standard command callback
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* @dumpit: callback for dumpers
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* @ops_list: operations list
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*/
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struct genl_ops
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{
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unsigned int cmd;
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unsigned int flags;
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struct nla_policy *policy;
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int (*doit)(struct sk_buff *skb,
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struct genl_info *info);
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int (*dumpit)(struct sk_buff *skb,
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struct netlink_callback *cb);
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struct list_head ops_list;
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};
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extern int genl_register_family(struct genl_family *family);
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extern int genl_unregister_family(struct genl_family *family);
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extern int genl_register_ops(struct genl_family *, struct genl_ops *ops);
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extern int genl_unregister_ops(struct genl_family *, struct genl_ops *ops);
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extern struct sock *genl_sock;
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/**
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* genlmsg_put - Add generic netlink header to netlink message
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* @skb: socket buffer holding the message
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* @pid: netlink pid the message is addressed to
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* @seq: sequence number (usually the one of the sender)
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* @type: netlink message type
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* @hdrlen: length of the user specific header
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* @flags netlink message flags
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* @cmd: generic netlink command
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* @version: version
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*
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* Returns pointer to user specific header
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*/
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static inline void *genlmsg_put(struct sk_buff *skb, u32 pid, u32 seq,
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int type, int hdrlen, int flags,
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u8 cmd, u8 version)
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{
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struct nlmsghdr *nlh;
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struct genlmsghdr *hdr;
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nlh = nlmsg_put(skb, pid, seq, type, GENL_HDRLEN + hdrlen, flags);
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if (nlh == NULL)
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return NULL;
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hdr = nlmsg_data(nlh);
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hdr->cmd = cmd;
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hdr->version = version;
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hdr->reserved = 0;
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return (char *) hdr + GENL_HDRLEN;
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}
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/**
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* genlmsg_end - Finalize a generic netlink message
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* @skb: socket buffer the message is stored in
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* @hdr: user specific header
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*/
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static inline int genlmsg_end(struct sk_buff *skb, void *hdr)
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{
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return nlmsg_end(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
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}
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/**
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* genlmsg_cancel - Cancel construction of a generic netlink message
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* @skb: socket buffer the message is stored in
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* @hdr: generic netlink message header
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*/
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static inline int genlmsg_cancel(struct sk_buff *skb, void *hdr)
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{
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return nlmsg_cancel(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN);
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}
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/**
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* genlmsg_multicast - multicast a netlink message
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* @skb: netlink message as socket buffer
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* @pid: own netlink pid to avoid sending to yourself
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* @group: multicast group id
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*/
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static inline int genlmsg_multicast(struct sk_buff *skb, u32 pid,
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unsigned int group)
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{
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return nlmsg_multicast(genl_sock, skb, pid, group);
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}
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/**
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* genlmsg_unicast - unicast a netlink message
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* @skb: netlink message as socket buffer
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* @pid: netlink pid of the destination socket
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*/
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static inline int genlmsg_unicast(struct sk_buff *skb, u32 pid)
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{
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return nlmsg_unicast(genl_sock, skb, pid);
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}
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#endif /* __NET_GENERIC_NETLINK_H */
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