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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> |
6 | * (C) 2005,2007 by Pablo Neira Ayuso <pablo@netfilter.org> |
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 | |
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> |
30 | #include <net/sock.h> |
31 | #include <net/netlink.h> |
32 | #include <linux/init.h> |
33 | |
34 | #include <linux/netlink.h> |
35 | #include <linux/netfilter/nfnetlink.h> |
36 | |
37 | MODULE_LICENSE("GPL"); |
38 | MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); |
39 | MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER); |
40 | |
41 | static char __initdata nfversion[] = "0.30"; |
42 | |
43 | static const struct nfnetlink_subsystem *subsys_table[NFNL_SUBSYS_COUNT]; |
44 | static DEFINE_MUTEX(nfnl_mutex); |
45 | |
46 | void nfnl_lock(void) |
47 | { |
48 | mutex_lock(&nfnl_mutex); |
49 | } |
50 | EXPORT_SYMBOL_GPL(nfnl_lock); |
51 | |
52 | void nfnl_unlock(void) |
53 | { |
54 | mutex_unlock(&nfnl_mutex); |
55 | } |
56 | EXPORT_SYMBOL_GPL(nfnl_unlock); |
57 | |
58 | int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n) |
59 | { |
60 | nfnl_lock(); |
61 | if (subsys_table[n->subsys_id]) { |
62 | nfnl_unlock(); |
63 | return -EBUSY; |
64 | } |
65 | subsys_table[n->subsys_id] = n; |
66 | nfnl_unlock(); |
67 | |
68 | return 0; |
69 | } |
70 | EXPORT_SYMBOL_GPL(nfnetlink_subsys_register); |
71 | |
72 | int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n) |
73 | { |
74 | nfnl_lock(); |
75 | subsys_table[n->subsys_id] = NULL; |
76 | nfnl_unlock(); |
77 | |
78 | return 0; |
79 | } |
80 | EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister); |
81 | |
82 | static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t type) |
83 | { |
84 | u_int8_t subsys_id = NFNL_SUBSYS_ID(type); |
85 | |
86 | if (subsys_id >= NFNL_SUBSYS_COUNT) |
87 | return NULL; |
88 | |
89 | return subsys_table[subsys_id]; |
90 | } |
91 | |
92 | static inline const struct nfnl_callback * |
93 | nfnetlink_find_client(u_int16_t type, const struct nfnetlink_subsystem *ss) |
94 | { |
95 | u_int8_t cb_id = NFNL_MSG_TYPE(type); |
96 | |
97 | if (cb_id >= ss->cb_count) |
98 | return NULL; |
99 | |
100 | return &ss->cb[cb_id]; |
101 | } |
102 | |
103 | int nfnetlink_has_listeners(struct net *net, unsigned int group) |
104 | { |
105 | return netlink_has_listeners(net->nfnl, group); |
106 | } |
107 | EXPORT_SYMBOL_GPL(nfnetlink_has_listeners); |
108 | |
109 | int nfnetlink_send(struct sk_buff *skb, struct net *net, u32 pid, |
110 | unsigned group, int echo, gfp_t flags) |
111 | { |
112 | return nlmsg_notify(net->nfnl, skb, pid, group, echo, flags); |
113 | } |
114 | EXPORT_SYMBOL_GPL(nfnetlink_send); |
115 | |
116 | int nfnetlink_set_err(struct net *net, u32 pid, u32 group, int error) |
117 | { |
118 | return netlink_set_err(net->nfnl, pid, group, error); |
119 | } |
120 | EXPORT_SYMBOL_GPL(nfnetlink_set_err); |
121 | |
122 | int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u_int32_t pid, int flags) |
123 | { |
124 | return netlink_unicast(net->nfnl, skb, pid, flags); |
125 | } |
126 | EXPORT_SYMBOL_GPL(nfnetlink_unicast); |
127 | |
128 | /* Process one complete nfnetlink message. */ |
129 | static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh) |
130 | { |
131 | struct net *net = sock_net(skb->sk); |
132 | const struct nfnl_callback *nc; |
133 | const struct nfnetlink_subsystem *ss; |
134 | int type, err; |
135 | |
136 | if (security_netlink_recv(skb, CAP_NET_ADMIN)) |
137 | return -EPERM; |
138 | |
139 | /* All the messages must at least contain nfgenmsg */ |
140 | if (nlh->nlmsg_len < NLMSG_LENGTH(sizeof(struct nfgenmsg))) |
141 | return 0; |
142 | |
143 | type = nlh->nlmsg_type; |
144 | replay: |
145 | ss = nfnetlink_get_subsys(type); |
146 | if (!ss) { |
147 | #ifdef CONFIG_MODULES |
148 | nfnl_unlock(); |
149 | request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type)); |
150 | nfnl_lock(); |
151 | ss = nfnetlink_get_subsys(type); |
152 | if (!ss) |
153 | #endif |
154 | return -EINVAL; |
155 | } |
156 | |
157 | nc = nfnetlink_find_client(type, ss); |
158 | if (!nc) |
159 | return -EINVAL; |
160 | |
161 | { |
162 | int min_len = NLMSG_SPACE(sizeof(struct nfgenmsg)); |
163 | u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type); |
164 | struct nlattr *cda[ss->cb[cb_id].attr_count + 1]; |
165 | struct nlattr *attr = (void *)nlh + min_len; |
166 | int attrlen = nlh->nlmsg_len - min_len; |
167 | |
168 | err = nla_parse(cda, ss->cb[cb_id].attr_count, |
169 | attr, attrlen, ss->cb[cb_id].policy); |
170 | if (err < 0) |
171 | return err; |
172 | |
173 | err = nc->call(net->nfnl, skb, nlh, (const struct nlattr **)cda); |
174 | if (err == -EAGAIN) |
175 | goto replay; |
176 | return err; |
177 | } |
178 | } |
179 | |
180 | static void nfnetlink_rcv(struct sk_buff *skb) |
181 | { |
182 | nfnl_lock(); |
183 | netlink_rcv_skb(skb, &nfnetlink_rcv_msg); |
184 | nfnl_unlock(); |
185 | } |
186 | |
187 | static int __net_init nfnetlink_net_init(struct net *net) |
188 | { |
189 | struct sock *nfnl; |
190 | |
191 | nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, NFNLGRP_MAX, |
192 | nfnetlink_rcv, NULL, THIS_MODULE); |
193 | if (!nfnl) |
194 | return -ENOMEM; |
195 | net->nfnl_stash = nfnl; |
196 | rcu_assign_pointer(net->nfnl, nfnl); |
197 | return 0; |
198 | } |
199 | |
200 | static void __net_exit nfnetlink_net_exit_batch(struct list_head *net_exit_list) |
201 | { |
202 | struct net *net; |
203 | |
204 | list_for_each_entry(net, net_exit_list, exit_list) |
205 | rcu_assign_pointer(net->nfnl, NULL); |
206 | synchronize_net(); |
207 | list_for_each_entry(net, net_exit_list, exit_list) |
208 | netlink_kernel_release(net->nfnl_stash); |
209 | } |
210 | |
211 | static struct pernet_operations nfnetlink_net_ops = { |
212 | .init = nfnetlink_net_init, |
213 | .exit_batch = nfnetlink_net_exit_batch, |
214 | }; |
215 | |
216 | static int __init nfnetlink_init(void) |
217 | { |
218 | printk("Netfilter messages via NETLINK v%s.\n", nfversion); |
219 | return register_pernet_subsys(&nfnetlink_net_ops); |
220 | } |
221 | |
222 | static void __exit nfnetlink_exit(void) |
223 | { |
224 | printk("Removing netfilter NETLINK layer.\n"); |
225 | unregister_pernet_subsys(&nfnetlink_net_ops); |
226 | } |
227 | module_init(nfnetlink_init); |
228 | module_exit(nfnetlink_exit); |
229 |
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