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 struct sock *nfnl = NULL; 44 static const struct nfnetlink_subsystem *subsys_table[NFNL_SUBSYS_COUNT]; 45 static DEFINE_MUTEX(nfnl_mutex); 46 47 void nfnl_lock(void) 48 { 49 mutex_lock(&nfnl_mutex); 50 } 51 EXPORT_SYMBOL_GPL(nfnl_lock); 52 53 void nfnl_unlock(void) 54 { 55 mutex_unlock(&nfnl_mutex); 56 } 57 EXPORT_SYMBOL_GPL(nfnl_unlock); 58 59 int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n) 60 { 61 nfnl_lock(); 62 if (subsys_table[n->subsys_id]) { 63 nfnl_unlock(); 64 return -EBUSY; 65 } 66 subsys_table[n->subsys_id] = n; 67 nfnl_unlock(); 68 69 return 0; 70 } 71 EXPORT_SYMBOL_GPL(nfnetlink_subsys_register); 72 73 int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n) 74 { 75 nfnl_lock(); 76 subsys_table[n->subsys_id] = NULL; 77 nfnl_unlock(); 78 79 return 0; 80 } 81 EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister); 82 83 static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t type) 84 { 85 u_int8_t subsys_id = NFNL_SUBSYS_ID(type); 86 87 if (subsys_id >= NFNL_SUBSYS_COUNT) 88 return NULL; 89 90 return subsys_table[subsys_id]; 91 } 92 93 static inline const struct nfnl_callback * 94 nfnetlink_find_client(u_int16_t type, const struct nfnetlink_subsystem *ss) 95 { 96 u_int8_t cb_id = NFNL_MSG_TYPE(type); 97 98 if (cb_id >= ss->cb_count) 99 return NULL; 100 101 return &ss->cb[cb_id]; 102 } 103 104 int nfnetlink_has_listeners(unsigned int group) 105 { 106 return netlink_has_listeners(nfnl, group); 107 } 108 EXPORT_SYMBOL_GPL(nfnetlink_has_listeners); 109 110 int nfnetlink_send(struct sk_buff *skb, u32 pid, unsigned group, int echo) 111 { 112 return nlmsg_notify(nfnl, skb, pid, group, echo, gfp_any()); 113 } 114 EXPORT_SYMBOL_GPL(nfnetlink_send); 115 116 int nfnetlink_unicast(struct sk_buff *skb, u_int32_t pid, int flags) 117 { 118 return netlink_unicast(nfnl, skb, pid, flags); 119 } 120 EXPORT_SYMBOL_GPL(nfnetlink_unicast); 121 122 /* Process one complete nfnetlink message. */ 123 static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh) 124 { 125 const struct nfnl_callback *nc; 126 const struct nfnetlink_subsystem *ss; 127 int type, err; 128 129 if (security_netlink_recv(skb, CAP_NET_ADMIN)) 130 return -EPERM; 131 132 /* All the messages must at least contain nfgenmsg */ 133 if (nlh->nlmsg_len < NLMSG_SPACE(sizeof(struct nfgenmsg))) 134 return 0; 135 136 type = nlh->nlmsg_type; 137 replay: 138 ss = nfnetlink_get_subsys(type); 139 if (!ss) { 140 #ifdef CONFIG_MODULES 141 nfnl_unlock(); 142 request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type)); 143 nfnl_lock(); 144 ss = nfnetlink_get_subsys(type); 145 if (!ss) 146 #endif 147 return -EINVAL; 148 } 149 150 nc = nfnetlink_find_client(type, ss); 151 if (!nc) 152 return -EINVAL; 153 154 { 155 int min_len = NLMSG_SPACE(sizeof(struct nfgenmsg)); 156 u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type); 157 u_int16_t attr_count = ss->cb[cb_id].attr_count; 158 struct nlattr *cda[attr_count+1]; 159 160 if (likely(nlh->nlmsg_len >= min_len)) { 161 struct nlattr *attr = (void *)nlh + NLMSG_ALIGN(min_len); 162 int attrlen = nlh->nlmsg_len - NLMSG_ALIGN(min_len); 163 164 err = nla_parse(cda, attr_count, attr, attrlen, 165 ss->cb[cb_id].policy); 166 if (err < 0) 167 return err; 168 } else 169 return -EINVAL; 170 171 err = nc->call(nfnl, skb, nlh, cda); 172 if (err == -EAGAIN) 173 goto replay; 174 return err; 175 } 176 } 177 178 static void nfnetlink_rcv(struct sk_buff *skb) 179 { 180 nfnl_lock(); 181 netlink_rcv_skb(skb, &nfnetlink_rcv_msg); 182 nfnl_unlock(); 183 } 184 185 static void __exit nfnetlink_exit(void) 186 { 187 printk("Removing netfilter NETLINK layer.\n"); 188 netlink_kernel_release(nfnl); 189 return; 190 } 191 192 static int __init nfnetlink_init(void) 193 { 194 printk("Netfilter messages via NETLINK v%s.\n", nfversion); 195 196 nfnl = netlink_kernel_create(&init_net, NETLINK_NETFILTER, NFNLGRP_MAX, 197 nfnetlink_rcv, NULL, THIS_MODULE); 198 if (!nfnl) { 199 printk(KERN_ERR "cannot initialize nfnetlink!\n"); 200 return -1; 201 } 202 203 return 0; 204 } 205 206 module_init(nfnetlink_init); 207 module_exit(nfnetlink_exit); 208