blob: bf23e489e4cdc88eec4a81a8c3461ac2cd5008ee [file] [log] [blame]
Harald Weltef9e815b2005-08-09 19:30:24 -07001/* Netfilter messages via netlink socket. Allows for user space
2 * protocol helpers and general trouble making from userspace.
3 *
4 * (C) 2001 by Jay Schulist <jschlst@samba.org>,
5 * (C) 2002-2005 by Harald Welte <laforge@gnumonks.org>
6 * (C) 2005 by Pablo Neira Ayuso <pablo@eurodev.net>
7 *
8 * Initial netfilter messages via netlink development funded and
9 * generally made possible by Network Robots, Inc. (www.networkrobots.com)
10 *
11 * Further development of this code funded by Astaro AG (http://www.astaro.com)
12 *
13 * This software may be used and distributed according to the terms
14 * of the GNU General Public License, incorporated herein by reference.
15 */
16
Harald Weltef9e815b2005-08-09 19:30:24 -070017#include <linux/module.h>
18#include <linux/types.h>
19#include <linux/socket.h>
20#include <linux/kernel.h>
21#include <linux/major.h>
Harald Weltef9e815b2005-08-09 19:30:24 -070022#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>
30#include <net/sock.h>
31#include <linux/init.h>
32#include <linux/spinlock.h>
33
34#include <linux/netfilter.h>
35#include <linux/netlink.h>
36#include <linux/netfilter/nfnetlink.h>
37
38MODULE_LICENSE("GPL");
Harald Welte4fdb3bb2005-08-09 19:40:55 -070039MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
40MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER);
Harald Weltef9e815b2005-08-09 19:30:24 -070041
42static char __initdata nfversion[] = "0.30";
43
44#if 0
Harald Welte0ab43f82005-08-09 19:43:44 -070045#define DEBUGP(format, args...) \
46 printk(KERN_DEBUG "%s(%d):%s(): " format, __FILE__, \
47 __LINE__, __FUNCTION__, ## args)
Harald Weltef9e815b2005-08-09 19:30:24 -070048#else
49#define DEBUGP(format, args...)
50#endif
51
52static struct sock *nfnl = NULL;
53static struct nfnetlink_subsystem *subsys_table[NFNL_SUBSYS_COUNT];
54DECLARE_MUTEX(nfnl_sem);
55
56void nfnl_lock(void)
57{
58 nfnl_shlock();
59}
60
61void nfnl_unlock(void)
62{
63 nfnl_shunlock();
64}
65
66int nfnetlink_subsys_register(struct nfnetlink_subsystem *n)
67{
68 DEBUGP("registering subsystem ID %u\n", n->subsys_id);
69
Harald Weltef9e815b2005-08-09 19:30:24 -070070 nfnl_lock();
Harald Welte0ab43f82005-08-09 19:43:44 -070071 if (subsys_table[n->subsys_id]) {
72 nfnl_unlock();
73 return -EBUSY;
74 }
Harald Weltef9e815b2005-08-09 19:30:24 -070075 subsys_table[n->subsys_id] = n;
76 nfnl_unlock();
77
78 return 0;
79}
80
81int nfnetlink_subsys_unregister(struct nfnetlink_subsystem *n)
82{
83 DEBUGP("unregistering subsystem ID %u\n", n->subsys_id);
84
85 nfnl_lock();
86 subsys_table[n->subsys_id] = NULL;
87 nfnl_unlock();
88
89 return 0;
90}
91
92static inline struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t type)
93{
94 u_int8_t subsys_id = NFNL_SUBSYS_ID(type);
95
96 if (subsys_id >= NFNL_SUBSYS_COUNT
97 || subsys_table[subsys_id] == NULL)
98 return NULL;
99
100 return subsys_table[subsys_id];
101}
102
103static inline struct nfnl_callback *
104nfnetlink_find_client(u_int16_t type, struct nfnetlink_subsystem *ss)
105{
106 u_int8_t cb_id = NFNL_MSG_TYPE(type);
YOSHIFUJI Hideaki601e68e2007-02-12 11:15:49 -0800107
Harald Weltef9e815b2005-08-09 19:30:24 -0700108 if (cb_id >= ss->cb_count) {
109 DEBUGP("msgtype %u >= %u, returning\n", type, ss->cb_count);
110 return NULL;
111 }
112
113 return &ss->cb[cb_id];
114}
115
116void __nfa_fill(struct sk_buff *skb, int attrtype, int attrlen,
117 const void *data)
118{
119 struct nfattr *nfa;
120 int size = NFA_LENGTH(attrlen);
121
122 nfa = (struct nfattr *)skb_put(skb, NFA_ALIGN(size));
123 nfa->nfa_type = attrtype;
124 nfa->nfa_len = size;
125 memcpy(NFA_DATA(nfa), data, attrlen);
Harald Welte080774a2005-08-09 19:32:58 -0700126 memset(NFA_DATA(nfa) + attrlen, 0, NFA_ALIGN(size) - size);
Harald Weltef9e815b2005-08-09 19:30:24 -0700127}
128
Harald Weltea2506c02005-11-09 12:59:13 -0800129void nfattr_parse(struct nfattr *tb[], int maxattr, struct nfattr *nfa, int len)
Harald Weltef9e815b2005-08-09 19:30:24 -0700130{
131 memset(tb, 0, sizeof(struct nfattr *) * maxattr);
132
133 while (NFA_OK(nfa, len)) {
Harald Welteebe0bbf2005-10-10 20:52:19 -0700134 unsigned flavor = NFA_TYPE(nfa);
Harald Weltef9e815b2005-08-09 19:30:24 -0700135 if (flavor && flavor <= maxattr)
136 tb[flavor-1] = nfa;
137 nfa = NFA_NEXT(nfa, len);
138 }
Harald Weltef9e815b2005-08-09 19:30:24 -0700139}
140
141/**
142 * nfnetlink_check_attributes - check and parse nfnetlink attributes
143 *
144 * subsys: nfnl subsystem for which this message is to be parsed
145 * nlmsghdr: netlink message to be checked/parsed
146 * cda: array of pointers, needs to be at least subsys->attr_count big
147 *
148 */
149static int
150nfnetlink_check_attributes(struct nfnetlink_subsystem *subsys,
151 struct nlmsghdr *nlh, struct nfattr *cda[])
152{
153 int min_len;
Harald Welte927ccbc2005-08-09 20:03:40 -0700154 u_int16_t attr_count;
155 u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
Harald Weltef9e815b2005-08-09 19:30:24 -0700156
Harald Welte927ccbc2005-08-09 20:03:40 -0700157 if (unlikely(cb_id >= subsys->cb_count)) {
158 DEBUGP("msgtype %u >= %u, returning\n",
159 cb_id, subsys->cb_count);
160 return -EINVAL;
161 }
Harald Welte927ccbc2005-08-09 20:03:40 -0700162
Yasuyuki Kozakai3ebbe0c2005-12-05 13:33:26 -0800163 min_len = NLMSG_SPACE(sizeof(struct nfgenmsg));
Harald Weltea42827b2005-08-09 20:03:54 -0700164 if (unlikely(nlh->nlmsg_len < min_len))
165 return -EINVAL;
166
167 attr_count = subsys->cb[cb_id].attr_count;
Harald Welte927ccbc2005-08-09 20:03:40 -0700168 memset(cda, 0, sizeof(struct nfattr *) * attr_count);
Harald Weltef9e815b2005-08-09 19:30:24 -0700169
170 /* check attribute lengths. */
Harald Weltea42827b2005-08-09 20:03:54 -0700171 if (likely(nlh->nlmsg_len > min_len)) {
Harald Weltef9e815b2005-08-09 19:30:24 -0700172 struct nfattr *attr = NFM_NFA(NLMSG_DATA(nlh));
173 int attrlen = nlh->nlmsg_len - NLMSG_ALIGN(min_len);
174
175 while (NFA_OK(attr, attrlen)) {
Harald Welteebe0bbf2005-10-10 20:52:19 -0700176 unsigned flavor = NFA_TYPE(attr);
Harald Weltef9e815b2005-08-09 19:30:24 -0700177 if (flavor) {
Harald Welte927ccbc2005-08-09 20:03:40 -0700178 if (flavor > attr_count)
Harald Weltef9e815b2005-08-09 19:30:24 -0700179 return -EINVAL;
180 cda[flavor - 1] = attr;
181 }
182 attr = NFA_NEXT(attr, attrlen);
183 }
Harald Weltea42827b2005-08-09 20:03:54 -0700184 }
185
186 /* implicit: if nlmsg_len == min_len, we return 0, and an empty
187 * (zeroed) cda[] array. The message is valid, but empty. */
Harald Weltef9e815b2005-08-09 19:30:24 -0700188
YOSHIFUJI Hideaki601e68e2007-02-12 11:15:49 -0800189 return 0;
Harald Weltef9e815b2005-08-09 19:30:24 -0700190}
191
Patrick McHardya2427692006-03-20 18:03:59 -0800192int nfnetlink_has_listeners(unsigned int group)
193{
194 return netlink_has_listeners(nfnl, group);
195}
196EXPORT_SYMBOL_GPL(nfnetlink_has_listeners);
197
Harald Weltef9e815b2005-08-09 19:30:24 -0700198int nfnetlink_send(struct sk_buff *skb, u32 pid, unsigned group, int echo)
199{
Harald Weltef9e815b2005-08-09 19:30:24 -0700200 int err = 0;
201
Patrick McHardyac6d4392005-08-14 19:29:52 -0700202 NETLINK_CB(skb).dst_group = group;
Harald Weltef9e815b2005-08-09 19:30:24 -0700203 if (echo)
204 atomic_inc(&skb->users);
Patrick McHardy44981212007-02-27 09:56:42 -0800205 netlink_broadcast(nfnl, skb, pid, group, gfp_any());
Harald Weltef9e815b2005-08-09 19:30:24 -0700206 if (echo)
207 err = netlink_unicast(nfnl, skb, pid, MSG_DONTWAIT);
208
209 return err;
210}
211
212int nfnetlink_unicast(struct sk_buff *skb, u_int32_t pid, int flags)
213{
214 return netlink_unicast(nfnl, skb, pid, flags);
215}
216
217/* Process one complete nfnetlink message. */
Arjan van de Ven858119e2006-01-14 13:20:43 -0800218static int nfnetlink_rcv_msg(struct sk_buff *skb,
Harald Weltef9e815b2005-08-09 19:30:24 -0700219 struct nlmsghdr *nlh, int *errp)
220{
221 struct nfnl_callback *nc;
222 struct nfnetlink_subsystem *ss;
223 int type, err = 0;
224
225 DEBUGP("entered; subsys=%u, msgtype=%u\n",
226 NFNL_SUBSYS_ID(nlh->nlmsg_type),
227 NFNL_MSG_TYPE(nlh->nlmsg_type));
228
Darrel Goeddelc7bdb542006-06-27 13:26:11 -0700229 if (security_netlink_recv(skb, CAP_NET_ADMIN)) {
Harald Welte37d2e7a2005-11-14 15:24:59 -0800230 DEBUGP("missing CAP_NET_ADMIN\n");
231 *errp = -EPERM;
232 return -1;
233 }
234
Harald Weltef9e815b2005-08-09 19:30:24 -0700235 /* Only requests are handled by kernel now. */
236 if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) {
237 DEBUGP("received non-request message\n");
238 return 0;
239 }
240
241 /* All the messages must at least contain nfgenmsg */
Yasuyuki Kozakai3ebbe0c2005-12-05 13:33:26 -0800242 if (nlh->nlmsg_len < NLMSG_SPACE(sizeof(struct nfgenmsg))) {
Harald Weltef9e815b2005-08-09 19:30:24 -0700243 DEBUGP("received message was too short\n");
244 return 0;
245 }
246
247 type = nlh->nlmsg_type;
248 ss = nfnetlink_get_subsys(type);
Harald Welte0ab43f82005-08-09 19:43:44 -0700249 if (!ss) {
250#ifdef CONFIG_KMOD
Harald Welte37d2e7a2005-11-14 15:24:59 -0800251 /* don't call nfnl_shunlock, since it would reenter
252 * with further packet processing */
253 up(&nfnl_sem);
254 request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type));
255 nfnl_shlock();
256 ss = nfnetlink_get_subsys(type);
Harald Welte0ab43f82005-08-09 19:43:44 -0700257 if (!ss)
258#endif
Harald Welteed77de92005-11-09 13:02:16 -0800259 goto err_inval;
Harald Welte0ab43f82005-08-09 19:43:44 -0700260 }
Harald Weltef9e815b2005-08-09 19:30:24 -0700261
262 nc = nfnetlink_find_client(type, ss);
263 if (!nc) {
264 DEBUGP("unable to find client for type %d\n", type);
265 goto err_inval;
266 }
267
Harald Weltef9e815b2005-08-09 19:30:24 -0700268 {
YOSHIFUJI Hideaki601e68e2007-02-12 11:15:49 -0800269 u_int16_t attr_count =
Harald Welte927ccbc2005-08-09 20:03:40 -0700270 ss->cb[NFNL_MSG_TYPE(nlh->nlmsg_type)].attr_count;
271 struct nfattr *cda[attr_count];
Harald Weltef9e815b2005-08-09 19:30:24 -0700272
Harald Welte927ccbc2005-08-09 20:03:40 -0700273 memset(cda, 0, sizeof(struct nfattr *) * attr_count);
YOSHIFUJI Hideaki601e68e2007-02-12 11:15:49 -0800274
Harald Weltef9e815b2005-08-09 19:30:24 -0700275 err = nfnetlink_check_attributes(ss, nlh, cda);
276 if (err < 0)
277 goto err_inval;
278
Harald Welte0ab43f82005-08-09 19:43:44 -0700279 DEBUGP("calling handler\n");
Harald Weltef9e815b2005-08-09 19:30:24 -0700280 err = nc->call(nfnl, skb, nlh, cda, errp);
281 *errp = err;
282 return err;
283 }
284
285err_inval:
Harald Welte0ab43f82005-08-09 19:43:44 -0700286 DEBUGP("returning -EINVAL\n");
Harald Weltef9e815b2005-08-09 19:30:24 -0700287 *errp = -EINVAL;
288 return -1;
289}
290
291/* Process one packet of messages. */
292static inline int nfnetlink_rcv_skb(struct sk_buff *skb)
293{
294 int err;
295 struct nlmsghdr *nlh;
296
297 while (skb->len >= NLMSG_SPACE(0)) {
298 u32 rlen;
299
300 nlh = (struct nlmsghdr *)skb->data;
301 if (nlh->nlmsg_len < sizeof(struct nlmsghdr)
302 || skb->len < nlh->nlmsg_len)
303 return 0;
304 rlen = NLMSG_ALIGN(nlh->nlmsg_len);
305 if (rlen > skb->len)
306 rlen = skb->len;
307 if (nfnetlink_rcv_msg(skb, nlh, &err)) {
308 if (!err)
309 return -1;
310 netlink_ack(skb, nlh, err);
311 } else
312 if (nlh->nlmsg_flags & NLM_F_ACK)
313 netlink_ack(skb, nlh, 0);
314 skb_pull(skb, rlen);
315 }
316
317 return 0;
318}
319
320static void nfnetlink_rcv(struct sock *sk, int len)
321{
322 do {
323 struct sk_buff *skb;
324
325 if (nfnl_shlock_nowait())
326 return;
327
328 while ((skb = skb_dequeue(&sk->sk_receive_queue)) != NULL) {
329 if (nfnetlink_rcv_skb(skb)) {
330 if (skb->len)
331 skb_queue_head(&sk->sk_receive_queue,
332 skb);
333 else
334 kfree_skb(skb);
335 break;
336 }
337 kfree_skb(skb);
338 }
339
Harald Welte0ab43f82005-08-09 19:43:44 -0700340 /* don't call nfnl_shunlock, since it would reenter
341 * with further packet processing */
Harald Weltef9e815b2005-08-09 19:30:24 -0700342 up(&nfnl_sem);
343 } while(nfnl && nfnl->sk_receive_queue.qlen);
344}
345
Adrian Bunk395dde22005-09-05 18:06:45 -0700346static void __exit nfnetlink_exit(void)
Harald Weltef9e815b2005-08-09 19:30:24 -0700347{
348 printk("Removing netfilter NETLINK layer.\n");
349 sock_release(nfnl->sk_socket);
350 return;
351}
352
Adrian Bunk395dde22005-09-05 18:06:45 -0700353static int __init nfnetlink_init(void)
Harald Weltef9e815b2005-08-09 19:30:24 -0700354{
355 printk("Netfilter messages via NETLINK v%s.\n", nfversion);
356
Patrick McHardy06628602005-08-15 12:33:26 -0700357 nfnl = netlink_kernel_create(NETLINK_NETFILTER, NFNLGRP_MAX,
YOSHIFUJI Hideaki601e68e2007-02-12 11:15:49 -0800358 nfnetlink_rcv, THIS_MODULE);
Harald Weltef9e815b2005-08-09 19:30:24 -0700359 if (!nfnl) {
360 printk(KERN_ERR "cannot initialize nfnetlink!\n");
361 return -1;
362 }
363
364 return 0;
365}
366
367module_init(nfnetlink_init);
368module_exit(nfnetlink_exit);
369
370EXPORT_SYMBOL_GPL(nfnetlink_subsys_register);
371EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister);
372EXPORT_SYMBOL_GPL(nfnetlink_send);
373EXPORT_SYMBOL_GPL(nfnetlink_unicast);
374EXPORT_SYMBOL_GPL(nfattr_parse);
375EXPORT_SYMBOL_GPL(__nfa_fill);