1 /* Netfilter messages via netlink socket. Allows for user space
2 * protocol helpers and general trouble making from userspace.
4 * (C) 2001 by Jay Schulist <jschlst@samba.org>,
5 * (C) 2002-2005 by Harald Welte <laforge@gnumonks.org>
6 * (C) 2005,2007 by Pablo Neira Ayuso <pablo@netfilter.org>
8 * Initial netfilter messages via netlink development funded and
9 * generally made possible by Network Robots, Inc. (www.networkrobots.com)
11 * Further development of this code funded by Astaro AG (http://www.astaro.com)
13 * This software may be used and distributed according to the terms
14 * of the GNU General Public License, incorporated herein by reference.
17 #include <linux/module.h>
18 #include <linux/types.h>
19 #include <linux/socket.h>
20 #include <linux/kernel.h>
21 #include <linux/major.h>
22 #include <linux/timer.h>
23 #include <linux/string.h>
24 #include <linux/sockios.h>
25 #include <linux/net.h>
26 #include <linux/fcntl.h>
27 #include <linux/skbuff.h>
28 #include <asm/uaccess.h>
29 #include <asm/system.h>
31 #include <net/netlink.h>
32 #include <linux/init.h>
33 #include <linux/spinlock.h>
35 #include <linux/netfilter.h>
36 #include <linux/netlink.h>
37 #include <linux/netfilter/nfnetlink.h>
39 MODULE_LICENSE("GPL");
40 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
41 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK
, NETLINK_NETFILTER
);
43 static char __initdata nfversion
[] = "0.30";
45 static struct sock
*nfnl
= NULL
;
46 static struct nfnetlink_subsystem
*subsys_table
[NFNL_SUBSYS_COUNT
];
47 static DEFINE_MUTEX(nfnl_mutex
);
49 static void nfnl_lock(void)
51 mutex_lock(&nfnl_mutex
);
54 static int nfnl_trylock(void)
56 return !mutex_trylock(&nfnl_mutex
);
59 static void __nfnl_unlock(void)
61 mutex_unlock(&nfnl_mutex
);
64 static void nfnl_unlock(void)
66 mutex_unlock(&nfnl_mutex
);
67 if (nfnl
->sk_receive_queue
.qlen
)
68 nfnl
->sk_data_ready(nfnl
, 0);
71 int nfnetlink_subsys_register(struct nfnetlink_subsystem
*n
)
74 if (subsys_table
[n
->subsys_id
]) {
78 subsys_table
[n
->subsys_id
] = n
;
84 int nfnetlink_subsys_unregister(struct nfnetlink_subsystem
*n
)
87 subsys_table
[n
->subsys_id
] = NULL
;
93 static inline struct nfnetlink_subsystem
*nfnetlink_get_subsys(u_int16_t type
)
95 u_int8_t subsys_id
= NFNL_SUBSYS_ID(type
);
97 if (subsys_id
>= NFNL_SUBSYS_COUNT
98 || subsys_table
[subsys_id
] == NULL
)
101 return subsys_table
[subsys_id
];
104 static inline struct nfnl_callback
*
105 nfnetlink_find_client(u_int16_t type
, struct nfnetlink_subsystem
*ss
)
107 u_int8_t cb_id
= NFNL_MSG_TYPE(type
);
109 if (cb_id
>= ss
->cb_count
)
112 return &ss
->cb
[cb_id
];
115 void __nfa_fill(struct sk_buff
*skb
, int attrtype
, int attrlen
,
119 int size
= NFA_LENGTH(attrlen
);
121 nfa
= (struct nfattr
*)skb_put(skb
, NFA_ALIGN(size
));
122 nfa
->nfa_type
= attrtype
;
124 memcpy(NFA_DATA(nfa
), data
, attrlen
);
125 memset(NFA_DATA(nfa
) + attrlen
, 0, NFA_ALIGN(size
) - size
);
128 void nfattr_parse(struct nfattr
*tb
[], int maxattr
, struct nfattr
*nfa
, int len
)
130 memset(tb
, 0, sizeof(struct nfattr
*) * maxattr
);
132 while (NFA_OK(nfa
, len
)) {
133 unsigned flavor
= NFA_TYPE(nfa
);
134 if (flavor
&& flavor
<= maxattr
)
136 nfa
= NFA_NEXT(nfa
, len
);
141 * nfnetlink_check_attributes - check and parse nfnetlink attributes
143 * subsys: nfnl subsystem for which this message is to be parsed
144 * nlmsghdr: netlink message to be checked/parsed
145 * cda: array of pointers, needs to be at least subsys->attr_count big
149 nfnetlink_check_attributes(struct nfnetlink_subsystem
*subsys
,
150 struct nlmsghdr
*nlh
, struct nfattr
*cda
[])
152 int min_len
= NLMSG_SPACE(sizeof(struct nfgenmsg
));
153 u_int16_t attr_count
;
154 u_int8_t cb_id
= NFNL_MSG_TYPE(nlh
->nlmsg_type
);
156 attr_count
= subsys
->cb
[cb_id
].attr_count
;
157 memset(cda
, 0, sizeof(struct nfattr
*) * attr_count
);
159 /* check attribute lengths. */
160 if (likely(nlh
->nlmsg_len
> min_len
)) {
161 struct nfattr
*attr
= NFM_NFA(NLMSG_DATA(nlh
));
162 int attrlen
= nlh
->nlmsg_len
- NLMSG_ALIGN(min_len
);
164 while (NFA_OK(attr
, attrlen
)) {
165 unsigned flavor
= NFA_TYPE(attr
);
167 if (flavor
> attr_count
)
169 cda
[flavor
- 1] = attr
;
171 attr
= NFA_NEXT(attr
, attrlen
);
175 /* implicit: if nlmsg_len == min_len, we return 0, and an empty
176 * (zeroed) cda[] array. The message is valid, but empty. */
181 int nfnetlink_has_listeners(unsigned int group
)
183 return netlink_has_listeners(nfnl
, group
);
185 EXPORT_SYMBOL_GPL(nfnetlink_has_listeners
);
187 int nfnetlink_send(struct sk_buff
*skb
, u32 pid
, unsigned group
, int echo
)
191 NETLINK_CB(skb
).dst_group
= group
;
193 atomic_inc(&skb
->users
);
194 netlink_broadcast(nfnl
, skb
, pid
, group
, gfp_any());
196 err
= netlink_unicast(nfnl
, skb
, pid
, MSG_DONTWAIT
);
201 int nfnetlink_unicast(struct sk_buff
*skb
, u_int32_t pid
, int flags
)
203 return netlink_unicast(nfnl
, skb
, pid
, flags
);
206 /* Process one complete nfnetlink message. */
207 static int nfnetlink_rcv_msg(struct sk_buff
*skb
,
208 struct nlmsghdr
*nlh
, int *errp
)
210 struct nfnl_callback
*nc
;
211 struct nfnetlink_subsystem
*ss
;
214 if (security_netlink_recv(skb
, CAP_NET_ADMIN
)) {
219 /* Only requests are handled by kernel now. */
220 if (!(nlh
->nlmsg_flags
& NLM_F_REQUEST
))
223 /* All the messages must at least contain nfgenmsg */
224 if (nlh
->nlmsg_len
< NLMSG_SPACE(sizeof(struct nfgenmsg
)))
227 type
= nlh
->nlmsg_type
;
228 ss
= nfnetlink_get_subsys(type
);
231 /* don't call nfnl_unlock, since it would reenter
232 * with further packet processing */
234 request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type
));
236 ss
= nfnetlink_get_subsys(type
);
242 nc
= nfnetlink_find_client(type
, ss
);
247 u_int16_t attr_count
=
248 ss
->cb
[NFNL_MSG_TYPE(nlh
->nlmsg_type
)].attr_count
;
249 struct nfattr
*cda
[attr_count
];
251 memset(cda
, 0, sizeof(struct nfattr
*) * attr_count
);
253 err
= nfnetlink_check_attributes(ss
, nlh
, cda
);
257 err
= nc
->call(nfnl
, skb
, nlh
, cda
, errp
);
267 static void nfnetlink_rcv(struct sock
*sk
, int len
)
269 unsigned int qlen
= 0;
274 netlink_run_queue(sk
, &qlen
, nfnetlink_rcv_msg
);
279 static void __exit
nfnetlink_exit(void)
281 printk("Removing netfilter NETLINK layer.\n");
282 sock_release(nfnl
->sk_socket
);
286 static int __init
nfnetlink_init(void)
288 printk("Netfilter messages via NETLINK v%s.\n", nfversion
);
290 nfnl
= netlink_kernel_create(NETLINK_NETFILTER
, NFNLGRP_MAX
,
291 nfnetlink_rcv
, THIS_MODULE
);
293 printk(KERN_ERR
"cannot initialize nfnetlink!\n");
300 module_init(nfnetlink_init
);
301 module_exit(nfnetlink_exit
);
303 EXPORT_SYMBOL_GPL(nfnetlink_subsys_register
);
304 EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister
);
305 EXPORT_SYMBOL_GPL(nfnetlink_send
);
306 EXPORT_SYMBOL_GPL(nfnetlink_unicast
);
307 EXPORT_SYMBOL_GPL(nfattr_parse
);
308 EXPORT_SYMBOL_GPL(__nfa_fill
);