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