xref: /linux-6.15/include/linux/netlink.h (revision facb4edc)
1 #ifndef __LINUX_NETLINK_H
2 #define __LINUX_NETLINK_H
3 
4 #include <linux/socket.h> /* for sa_family_t */
5 #include <linux/types.h>
6 
7 #define NETLINK_ROUTE		0	/* Routing/device hook				*/
8 #define NETLINK_UNUSED		1	/* Unused number				*/
9 #define NETLINK_USERSOCK	2	/* Reserved for user mode socket protocols 	*/
10 #define NETLINK_FIREWALL	3	/* Firewalling hook				*/
11 #define NETLINK_INET_DIAG	4	/* INET socket monitoring			*/
12 #define NETLINK_NFLOG		5	/* netfilter/iptables ULOG */
13 #define NETLINK_XFRM		6	/* ipsec */
14 #define NETLINK_SELINUX		7	/* SELinux event notifications */
15 #define NETLINK_ISCSI		8	/* Open-iSCSI */
16 #define NETLINK_AUDIT		9	/* auditing */
17 #define NETLINK_FIB_LOOKUP	10
18 #define NETLINK_CONNECTOR	11
19 #define NETLINK_NETFILTER	12	/* netfilter subsystem */
20 #define NETLINK_IP6_FW		13
21 #define NETLINK_DNRTMSG		14	/* DECnet routing messages */
22 #define NETLINK_KOBJECT_UEVENT	15	/* Kernel messages to userspace */
23 #define NETLINK_GENERIC		16
24 /* leave room for NETLINK_DM (DM Events) */
25 #define NETLINK_SCSITRANSPORT	18	/* SCSI Transports */
26 #define NETLINK_ECRYPTFS	19
27 
28 #define MAX_LINKS 32
29 
30 struct sockaddr_nl {
31 	sa_family_t	nl_family;	/* AF_NETLINK	*/
32 	unsigned short	nl_pad;		/* zero		*/
33 	__u32		nl_pid;		/* port ID	*/
34        	__u32		nl_groups;	/* multicast groups mask */
35 };
36 
37 struct nlmsghdr {
38 	__u32		nlmsg_len;	/* Length of message including header */
39 	__u16		nlmsg_type;	/* Message content */
40 	__u16		nlmsg_flags;	/* Additional flags */
41 	__u32		nlmsg_seq;	/* Sequence number */
42 	__u32		nlmsg_pid;	/* Sending process port ID */
43 };
44 
45 /* Flags values */
46 
47 #define NLM_F_REQUEST		1	/* It is request message. 	*/
48 #define NLM_F_MULTI		2	/* Multipart message, terminated by NLMSG_DONE */
49 #define NLM_F_ACK		4	/* Reply with ack, with zero or error code */
50 #define NLM_F_ECHO		8	/* Echo this request 		*/
51 
52 /* Modifiers to GET request */
53 #define NLM_F_ROOT	0x100	/* specify tree	root	*/
54 #define NLM_F_MATCH	0x200	/* return all matching	*/
55 #define NLM_F_ATOMIC	0x400	/* atomic GET		*/
56 #define NLM_F_DUMP	(NLM_F_ROOT|NLM_F_MATCH)
57 
58 /* Modifiers to NEW request */
59 #define NLM_F_REPLACE	0x100	/* Override existing		*/
60 #define NLM_F_EXCL	0x200	/* Do not touch, if it exists	*/
61 #define NLM_F_CREATE	0x400	/* Create, if it does not exist	*/
62 #define NLM_F_APPEND	0x800	/* Add to end of list		*/
63 
64 /*
65    4.4BSD ADD		NLM_F_CREATE|NLM_F_EXCL
66    4.4BSD CHANGE	NLM_F_REPLACE
67 
68    True CHANGE		NLM_F_CREATE|NLM_F_REPLACE
69    Append		NLM_F_CREATE
70    Check		NLM_F_EXCL
71  */
72 
73 #define NLMSG_ALIGNTO	4U
74 #define NLMSG_ALIGN(len) ( ((len)+NLMSG_ALIGNTO-1) & ~(NLMSG_ALIGNTO-1) )
75 #define NLMSG_HDRLEN	 ((int) NLMSG_ALIGN(sizeof(struct nlmsghdr)))
76 #define NLMSG_LENGTH(len) ((len)+NLMSG_ALIGN(NLMSG_HDRLEN))
77 #define NLMSG_SPACE(len) NLMSG_ALIGN(NLMSG_LENGTH(len))
78 #define NLMSG_DATA(nlh)  ((void*)(((char*)nlh) + NLMSG_LENGTH(0)))
79 #define NLMSG_NEXT(nlh,len)	 ((len) -= NLMSG_ALIGN((nlh)->nlmsg_len), \
80 				  (struct nlmsghdr*)(((char*)(nlh)) + NLMSG_ALIGN((nlh)->nlmsg_len)))
81 #define NLMSG_OK(nlh,len) ((len) >= (int)sizeof(struct nlmsghdr) && \
82 			   (nlh)->nlmsg_len >= sizeof(struct nlmsghdr) && \
83 			   (nlh)->nlmsg_len <= (len))
84 #define NLMSG_PAYLOAD(nlh,len) ((nlh)->nlmsg_len - NLMSG_SPACE((len)))
85 
86 #define NLMSG_NOOP		0x1	/* Nothing.		*/
87 #define NLMSG_ERROR		0x2	/* Error		*/
88 #define NLMSG_DONE		0x3	/* End of a dump	*/
89 #define NLMSG_OVERRUN		0x4	/* Data lost		*/
90 
91 #define NLMSG_MIN_TYPE		0x10	/* < 0x10: reserved control messages */
92 
93 struct nlmsgerr {
94 	int		error;
95 	struct nlmsghdr msg;
96 };
97 
98 #define NETLINK_ADD_MEMBERSHIP	1
99 #define NETLINK_DROP_MEMBERSHIP	2
100 #define NETLINK_PKTINFO		3
101 #define NETLINK_BROADCAST_ERROR	4
102 #define NETLINK_NO_ENOBUFS	5
103 
104 struct nl_pktinfo {
105 	__u32	group;
106 };
107 
108 #define NET_MAJOR 36		/* Major 36 is reserved for networking 						*/
109 
110 enum {
111 	NETLINK_UNCONNECTED = 0,
112 	NETLINK_CONNECTED,
113 };
114 
115 /*
116  *  <------- NLA_HDRLEN ------> <-- NLA_ALIGN(payload)-->
117  * +---------------------+- - -+- - - - - - - - - -+- - -+
118  * |        Header       | Pad |     Payload       | Pad |
119  * |   (struct nlattr)   | ing |                   | ing |
120  * +---------------------+- - -+- - - - - - - - - -+- - -+
121  *  <-------------- nlattr->nla_len -------------->
122  */
123 
124 struct nlattr {
125 	__u16           nla_len;
126 	__u16           nla_type;
127 };
128 
129 /*
130  * nla_type (16 bits)
131  * +---+---+-------------------------------+
132  * | N | O | Attribute Type                |
133  * +---+---+-------------------------------+
134  * N := Carries nested attributes
135  * O := Payload stored in network byte order
136  *
137  * Note: The N and O flag are mutually exclusive.
138  */
139 #define NLA_F_NESTED		(1 << 15)
140 #define NLA_F_NET_BYTEORDER	(1 << 14)
141 #define NLA_TYPE_MASK		~(NLA_F_NESTED | NLA_F_NET_BYTEORDER)
142 
143 #define NLA_ALIGNTO		4
144 #define NLA_ALIGN(len)		(((len) + NLA_ALIGNTO - 1) & ~(NLA_ALIGNTO - 1))
145 #define NLA_HDRLEN		((int) NLA_ALIGN(sizeof(struct nlattr)))
146 
147 #ifdef __KERNEL__
148 
149 #include <linux/capability.h>
150 #include <linux/skbuff.h>
151 
152 struct net;
153 
154 static inline struct nlmsghdr *nlmsg_hdr(const struct sk_buff *skb)
155 {
156 	return (struct nlmsghdr *)skb->data;
157 }
158 
159 struct netlink_skb_parms {
160 	struct ucred		creds;		/* Skb credentials	*/
161 	__u32			pid;
162 	__u32			dst_group;
163 	kernel_cap_t		eff_cap;
164 	__u32			loginuid;	/* Login (audit) uid */
165 	__u32			sessionid;	/* Session id (audit) */
166 	__u32			sid;		/* SELinux security id */
167 };
168 
169 #define NETLINK_CB(skb)		(*(struct netlink_skb_parms*)&((skb)->cb))
170 #define NETLINK_CREDS(skb)	(&NETLINK_CB((skb)).creds)
171 
172 
173 extern void netlink_table_grab(void);
174 extern void netlink_table_ungrab(void);
175 
176 extern struct sock *netlink_kernel_create(struct net *net,
177 					  int unit,unsigned int groups,
178 					  void (*input)(struct sk_buff *skb),
179 					  struct mutex *cb_mutex,
180 					  struct module *module);
181 extern void netlink_kernel_release(struct sock *sk);
182 extern int __netlink_change_ngroups(struct sock *sk, unsigned int groups);
183 extern int netlink_change_ngroups(struct sock *sk, unsigned int groups);
184 extern void __netlink_clear_multicast_users(struct sock *sk, unsigned int group);
185 extern void netlink_clear_multicast_users(struct sock *sk, unsigned int group);
186 extern void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err);
187 extern int netlink_has_listeners(struct sock *sk, unsigned int group);
188 extern int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 pid, int nonblock);
189 extern int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 pid,
190 			     __u32 group, gfp_t allocation);
191 extern int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb,
192 	__u32 pid, __u32 group, gfp_t allocation,
193 	int (*filter)(struct sock *dsk, struct sk_buff *skb, void *data),
194 	void *filter_data);
195 extern int netlink_set_err(struct sock *ssk, __u32 pid, __u32 group, int code);
196 extern int netlink_register_notifier(struct notifier_block *nb);
197 extern int netlink_unregister_notifier(struct notifier_block *nb);
198 
199 /* finegrained unicast helpers: */
200 struct sock *netlink_getsockbyfilp(struct file *filp);
201 int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
202 		      long *timeo, struct sock *ssk);
203 void netlink_detachskb(struct sock *sk, struct sk_buff *skb);
204 int netlink_sendskb(struct sock *sk, struct sk_buff *skb);
205 
206 /*
207  *	skb should fit one page. This choice is good for headerless malloc.
208  *	But we should limit to 8K so that userspace does not have to
209  *	use enormous buffer sizes on recvmsg() calls just to avoid
210  *	MSG_TRUNC when PAGE_SIZE is very large.
211  */
212 #if PAGE_SIZE < 8192UL
213 #define NLMSG_GOODSIZE	SKB_WITH_OVERHEAD(PAGE_SIZE)
214 #else
215 #define NLMSG_GOODSIZE	SKB_WITH_OVERHEAD(8192UL)
216 #endif
217 
218 #define NLMSG_DEFAULT_SIZE (NLMSG_GOODSIZE - NLMSG_HDRLEN)
219 
220 
221 struct netlink_callback {
222 	struct sk_buff		*skb;
223 	const struct nlmsghdr	*nlh;
224 	int			(*dump)(struct sk_buff * skb,
225 					struct netlink_callback *cb);
226 	int			(*done)(struct netlink_callback *cb);
227 	int			family;
228 	long			args[6];
229 };
230 
231 struct netlink_notify {
232 	struct net *net;
233 	int pid;
234 	int protocol;
235 };
236 
237 static __inline__ struct nlmsghdr *
238 __nlmsg_put(struct sk_buff *skb, u32 pid, u32 seq, int type, int len, int flags)
239 {
240 	struct nlmsghdr *nlh;
241 	int size = NLMSG_LENGTH(len);
242 
243 	nlh = (struct nlmsghdr*)skb_put(skb, NLMSG_ALIGN(size));
244 	nlh->nlmsg_type = type;
245 	nlh->nlmsg_len = size;
246 	nlh->nlmsg_flags = flags;
247 	nlh->nlmsg_pid = pid;
248 	nlh->nlmsg_seq = seq;
249 	if (!__builtin_constant_p(size) || NLMSG_ALIGN(size) - size != 0)
250 		memset(NLMSG_DATA(nlh) + len, 0, NLMSG_ALIGN(size) - size);
251 	return nlh;
252 }
253 
254 #define NLMSG_NEW(skb, pid, seq, type, len, flags) \
255 ({	if (unlikely(skb_tailroom(skb) < (int)NLMSG_SPACE(len))) \
256 		goto nlmsg_failure; \
257 	__nlmsg_put(skb, pid, seq, type, len, flags); })
258 
259 #define NLMSG_PUT(skb, pid, seq, type, len) \
260 	NLMSG_NEW(skb, pid, seq, type, len, 0)
261 
262 extern int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
263 			      const struct nlmsghdr *nlh,
264 			      int (*dump)(struct sk_buff *skb, struct netlink_callback*),
265 			      int (*done)(struct netlink_callback*));
266 
267 
268 #define NL_NONROOT_RECV 0x1
269 #define NL_NONROOT_SEND 0x2
270 extern void netlink_set_nonroot(int protocol, unsigned flag);
271 
272 #endif /* __KERNEL__ */
273 
274 #endif	/* __LINUX_NETLINK_H */
275