Commit | Line | Data |
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f9e815b3 HW |
1 | /* 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> | |
67ca3966 | 6 | * (C) 2005,2007 by Pablo Neira Ayuso <pablo@netfilter.org> |
f9e815b3 HW |
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 | ||
f9e815b3 HW |
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> | |
f9e815b3 HW |
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> | |
30 | #include <net/sock.h> | |
a3c5029c | 31 | #include <net/netlink.h> |
f9e815b3 | 32 | #include <linux/init.h> |
f9e815b3 | 33 | |
f9e815b3 HW |
34 | #include <linux/netlink.h> |
35 | #include <linux/netfilter/nfnetlink.h> | |
36 | ||
37 | MODULE_LICENSE("GPL"); | |
4fdb3bb7 HW |
38 | MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); |
39 | MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER); | |
f9e815b3 HW |
40 | |
41 | static char __initdata nfversion[] = "0.30"; | |
42 | ||
f9e815b3 HW |
43 | static struct sock *nfnl = NULL; |
44 | static struct nfnetlink_subsystem *subsys_table[NFNL_SUBSYS_COUNT]; | |
a3c5029c | 45 | static DEFINE_MUTEX(nfnl_mutex); |
f9e815b3 | 46 | |
a3c5029c | 47 | static void nfnl_lock(void) |
f9e815b3 | 48 | { |
a3c5029c | 49 | mutex_lock(&nfnl_mutex); |
f9e815b3 HW |
50 | } |
51 | ||
a3c5029c | 52 | static int nfnl_trylock(void) |
f9e815b3 | 53 | { |
a3c5029c PM |
54 | return !mutex_trylock(&nfnl_mutex); |
55 | } | |
56 | ||
57 | static void __nfnl_unlock(void) | |
58 | { | |
59 | mutex_unlock(&nfnl_mutex); | |
60 | } | |
61 | ||
62 | static void nfnl_unlock(void) | |
63 | { | |
64 | mutex_unlock(&nfnl_mutex); | |
65 | if (nfnl->sk_receive_queue.qlen) | |
66 | nfnl->sk_data_ready(nfnl, 0); | |
f9e815b3 HW |
67 | } |
68 | ||
69 | int nfnetlink_subsys_register(struct nfnetlink_subsystem *n) | |
70 | { | |
f9e815b3 | 71 | nfnl_lock(); |
0ab43f84 HW |
72 | if (subsys_table[n->subsys_id]) { |
73 | nfnl_unlock(); | |
74 | return -EBUSY; | |
75 | } | |
f9e815b3 HW |
76 | subsys_table[n->subsys_id] = n; |
77 | nfnl_unlock(); | |
78 | ||
79 | return 0; | |
80 | } | |
81 | ||
82 | int nfnetlink_subsys_unregister(struct nfnetlink_subsystem *n) | |
83 | { | |
f9e815b3 HW |
84 | nfnl_lock(); |
85 | subsys_table[n->subsys_id] = NULL; | |
86 | nfnl_unlock(); | |
87 | ||
88 | return 0; | |
89 | } | |
90 | ||
91 | static inline struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t type) | |
92 | { | |
93 | u_int8_t subsys_id = NFNL_SUBSYS_ID(type); | |
94 | ||
ac0f1d98 | 95 | if (subsys_id >= NFNL_SUBSYS_COUNT) |
f9e815b3 HW |
96 | return NULL; |
97 | ||
98 | return subsys_table[subsys_id]; | |
99 | } | |
100 | ||
101 | static inline struct nfnl_callback * | |
102 | nfnetlink_find_client(u_int16_t type, struct nfnetlink_subsystem *ss) | |
103 | { | |
104 | u_int8_t cb_id = NFNL_MSG_TYPE(type); | |
601e68e1 | 105 | |
67ca3966 | 106 | if (cb_id >= ss->cb_count) |
f9e815b3 | 107 | return NULL; |
f9e815b3 HW |
108 | |
109 | return &ss->cb[cb_id]; | |
110 | } | |
111 | ||
112 | void __nfa_fill(struct sk_buff *skb, int attrtype, int attrlen, | |
113 | const void *data) | |
114 | { | |
115 | struct nfattr *nfa; | |
116 | int size = NFA_LENGTH(attrlen); | |
117 | ||
118 | nfa = (struct nfattr *)skb_put(skb, NFA_ALIGN(size)); | |
119 | nfa->nfa_type = attrtype; | |
120 | nfa->nfa_len = size; | |
121 | memcpy(NFA_DATA(nfa), data, attrlen); | |
080774a2 | 122 | memset(NFA_DATA(nfa) + attrlen, 0, NFA_ALIGN(size) - size); |
f9e815b3 HW |
123 | } |
124 | ||
a2506c04 | 125 | void nfattr_parse(struct nfattr *tb[], int maxattr, struct nfattr *nfa, int len) |
f9e815b3 HW |
126 | { |
127 | memset(tb, 0, sizeof(struct nfattr *) * maxattr); | |
128 | ||
129 | while (NFA_OK(nfa, len)) { | |
ebe0bbf0 | 130 | unsigned flavor = NFA_TYPE(nfa); |
f9e815b3 HW |
131 | if (flavor && flavor <= maxattr) |
132 | tb[flavor-1] = nfa; | |
133 | nfa = NFA_NEXT(nfa, len); | |
134 | } | |
f9e815b3 HW |
135 | } |
136 | ||
137 | /** | |
138 | * nfnetlink_check_attributes - check and parse nfnetlink attributes | |
139 | * | |
140 | * subsys: nfnl subsystem for which this message is to be parsed | |
141 | * nlmsghdr: netlink message to be checked/parsed | |
142 | * cda: array of pointers, needs to be at least subsys->attr_count big | |
143 | * | |
144 | */ | |
145 | static int | |
146 | nfnetlink_check_attributes(struct nfnetlink_subsystem *subsys, | |
147 | struct nlmsghdr *nlh, struct nfattr *cda[]) | |
148 | { | |
d9e6d029 | 149 | int min_len = NLMSG_SPACE(sizeof(struct nfgenmsg)); |
927ccbcc HW |
150 | u_int16_t attr_count; |
151 | u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type); | |
f9e815b3 | 152 | |
a42827b7 HW |
153 | attr_count = subsys->cb[cb_id].attr_count; |
154 | memset(cda, 0, sizeof(struct nfattr *) * attr_count); | |
155 | ||
156 | /* check attribute lengths. */ | |
157 | if (likely(nlh->nlmsg_len > min_len)) { | |
f9e815b3 HW |
158 | struct nfattr *attr = NFM_NFA(NLMSG_DATA(nlh)); |
159 | int attrlen = nlh->nlmsg_len - NLMSG_ALIGN(min_len); | |
160 | ||
161 | while (NFA_OK(attr, attrlen)) { | |
ebe0bbf0 | 162 | unsigned flavor = NFA_TYPE(attr); |
f9e815b3 | 163 | if (flavor) { |
927ccbcc | 164 | if (flavor > attr_count) |
f9e815b3 HW |
165 | return -EINVAL; |
166 | cda[flavor - 1] = attr; | |
167 | } | |
168 | attr = NFA_NEXT(attr, attrlen); | |
169 | } | |
a42827b7 HW |
170 | } |
171 | ||
172 | /* implicit: if nlmsg_len == min_len, we return 0, and an empty | |
173 | * (zeroed) cda[] array. The message is valid, but empty. */ | |
f9e815b3 | 174 | |
601e68e1 | 175 | return 0; |
f9e815b3 HW |
176 | } |
177 | ||
a2427692 PM |
178 | int nfnetlink_has_listeners(unsigned int group) |
179 | { | |
180 | return netlink_has_listeners(nfnl, group); | |
181 | } | |
182 | EXPORT_SYMBOL_GPL(nfnetlink_has_listeners); | |
183 | ||
f9e815b3 HW |
184 | int nfnetlink_send(struct sk_buff *skb, u32 pid, unsigned group, int echo) |
185 | { | |
f9e815b3 HW |
186 | int err = 0; |
187 | ||
ac6d439d | 188 | NETLINK_CB(skb).dst_group = group; |
f9e815b3 HW |
189 | if (echo) |
190 | atomic_inc(&skb->users); | |
4498121c | 191 | netlink_broadcast(nfnl, skb, pid, group, gfp_any()); |
f9e815b3 HW |
192 | if (echo) |
193 | err = netlink_unicast(nfnl, skb, pid, MSG_DONTWAIT); | |
194 | ||
195 | return err; | |
196 | } | |
197 | ||
198 | int nfnetlink_unicast(struct sk_buff *skb, u_int32_t pid, int flags) | |
199 | { | |
200 | return netlink_unicast(nfnl, skb, pid, flags); | |
201 | } | |
202 | ||
203 | /* Process one complete nfnetlink message. */ | |
858119e1 | 204 | static int nfnetlink_rcv_msg(struct sk_buff *skb, |
f9e815b3 HW |
205 | struct nlmsghdr *nlh, int *errp) |
206 | { | |
207 | struct nfnl_callback *nc; | |
208 | struct nfnetlink_subsystem *ss; | |
209 | int type, err = 0; | |
210 | ||
c7bdb545 | 211 | if (security_netlink_recv(skb, CAP_NET_ADMIN)) { |
37d2e7a2 HW |
212 | *errp = -EPERM; |
213 | return -1; | |
214 | } | |
215 | ||
f9e815b3 | 216 | /* Only requests are handled by kernel now. */ |
67ca3966 | 217 | if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) |
f9e815b3 | 218 | return 0; |
f9e815b3 HW |
219 | |
220 | /* All the messages must at least contain nfgenmsg */ | |
67ca3966 | 221 | if (nlh->nlmsg_len < NLMSG_SPACE(sizeof(struct nfgenmsg))) |
f9e815b3 | 222 | return 0; |
f9e815b3 HW |
223 | |
224 | type = nlh->nlmsg_type; | |
225 | ss = nfnetlink_get_subsys(type); | |
0ab43f84 HW |
226 | if (!ss) { |
227 | #ifdef CONFIG_KMOD | |
a3c5029c | 228 | /* don't call nfnl_unlock, since it would reenter |
37d2e7a2 | 229 | * with further packet processing */ |
a3c5029c | 230 | __nfnl_unlock(); |
37d2e7a2 | 231 | request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type)); |
a3c5029c | 232 | nfnl_lock(); |
37d2e7a2 | 233 | ss = nfnetlink_get_subsys(type); |
0ab43f84 HW |
234 | if (!ss) |
235 | #endif | |
ed77de9f | 236 | goto err_inval; |
0ab43f84 | 237 | } |
f9e815b3 HW |
238 | |
239 | nc = nfnetlink_find_client(type, ss); | |
67ca3966 | 240 | if (!nc) |
f9e815b3 | 241 | goto err_inval; |
f9e815b3 | 242 | |
f9e815b3 | 243 | { |
601e68e1 | 244 | u_int16_t attr_count = |
927ccbcc HW |
245 | ss->cb[NFNL_MSG_TYPE(nlh->nlmsg_type)].attr_count; |
246 | struct nfattr *cda[attr_count]; | |
f9e815b3 | 247 | |
927ccbcc | 248 | memset(cda, 0, sizeof(struct nfattr *) * attr_count); |
601e68e1 | 249 | |
f9e815b3 HW |
250 | err = nfnetlink_check_attributes(ss, nlh, cda); |
251 | if (err < 0) | |
252 | goto err_inval; | |
253 | ||
254 | err = nc->call(nfnl, skb, nlh, cda, errp); | |
255 | *errp = err; | |
256 | return err; | |
257 | } | |
258 | ||
259 | err_inval: | |
260 | *errp = -EINVAL; | |
261 | return -1; | |
262 | } | |
263 | ||
f9e815b3 HW |
264 | static void nfnetlink_rcv(struct sock *sk, int len) |
265 | { | |
73c36186 | 266 | unsigned int qlen = 0; |
f9e815b3 | 267 | |
73c36186 | 268 | do { |
a3c5029c | 269 | if (nfnl_trylock()) |
f9e815b3 | 270 | return; |
73c36186 | 271 | netlink_run_queue(sk, &qlen, nfnetlink_rcv_msg); |
a3c5029c | 272 | __nfnl_unlock(); |
73c36186 | 273 | } while (qlen); |
f9e815b3 HW |
274 | } |
275 | ||
395dde20 | 276 | static void __exit nfnetlink_exit(void) |
f9e815b3 HW |
277 | { |
278 | printk("Removing netfilter NETLINK layer.\n"); | |
279 | sock_release(nfnl->sk_socket); | |
280 | return; | |
281 | } | |
282 | ||
395dde20 | 283 | static int __init nfnetlink_init(void) |
f9e815b3 HW |
284 | { |
285 | printk("Netfilter messages via NETLINK v%s.\n", nfversion); | |
286 | ||
06628607 | 287 | nfnl = netlink_kernel_create(NETLINK_NETFILTER, NFNLGRP_MAX, |
601e68e1 | 288 | nfnetlink_rcv, THIS_MODULE); |
f9e815b3 HW |
289 | if (!nfnl) { |
290 | printk(KERN_ERR "cannot initialize nfnetlink!\n"); | |
291 | return -1; | |
292 | } | |
293 | ||
294 | return 0; | |
295 | } | |
296 | ||
297 | module_init(nfnetlink_init); | |
298 | module_exit(nfnetlink_exit); | |
299 | ||
300 | EXPORT_SYMBOL_GPL(nfnetlink_subsys_register); | |
301 | EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister); | |
302 | EXPORT_SYMBOL_GPL(nfnetlink_send); | |
303 | EXPORT_SYMBOL_GPL(nfnetlink_unicast); | |
304 | EXPORT_SYMBOL_GPL(nfattr_parse); | |
305 | EXPORT_SYMBOL_GPL(__nfa_fill); |