| /* Netfilter messages via netlink socket. Allows for user space |
| * protocol helpers and general trouble making from userspace. |
| * |
| * (C) 2001 by Jay Schulist <jschlst@samba.org>, |
| * (C) 2002-2005 by Harald Welte <laforge@gnumonks.org> |
| * (C) 2005,2007 by Pablo Neira Ayuso <pablo@netfilter.org> |
| * |
| * Initial netfilter messages via netlink development funded and |
| * generally made possible by Network Robots, Inc. (www.networkrobots.com) |
| * |
| * Further development of this code funded by Astaro AG (http://www.astaro.com) |
| * |
| * This software may be used and distributed according to the terms |
| * of the GNU General Public License, incorporated herein by reference. |
| */ |
| |
| #include <linux/module.h> |
| #include <linux/types.h> |
| #include <linux/socket.h> |
| #include <linux/kernel.h> |
| #include <linux/major.h> |
| #include <linux/timer.h> |
| #include <linux/string.h> |
| #include <linux/sockios.h> |
| #include <linux/net.h> |
| #include <linux/fcntl.h> |
| #include <linux/skbuff.h> |
| #include <asm/uaccess.h> |
| #include <asm/system.h> |
| #include <net/sock.h> |
| #include <net/netlink.h> |
| #include <linux/init.h> |
| |
| #include <linux/netlink.h> |
| #include <linux/netfilter/nfnetlink.h> |
| |
| MODULE_LICENSE("GPL"); |
| MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); |
| MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER); |
| |
| static char __initdata nfversion[] = "0.30"; |
| |
| static struct sock *nfnl = NULL; |
| static struct nfnetlink_subsystem *subsys_table[NFNL_SUBSYS_COUNT]; |
| static DEFINE_MUTEX(nfnl_mutex); |
| |
| static void nfnl_lock(void) |
| { |
| mutex_lock(&nfnl_mutex); |
| } |
| |
| static int nfnl_trylock(void) |
| { |
| return !mutex_trylock(&nfnl_mutex); |
| } |
| |
| static void __nfnl_unlock(void) |
| { |
| mutex_unlock(&nfnl_mutex); |
| } |
| |
| static void nfnl_unlock(void) |
| { |
| mutex_unlock(&nfnl_mutex); |
| if (nfnl->sk_receive_queue.qlen) |
| nfnl->sk_data_ready(nfnl, 0); |
| } |
| |
| int nfnetlink_subsys_register(struct nfnetlink_subsystem *n) |
| { |
| nfnl_lock(); |
| if (subsys_table[n->subsys_id]) { |
| nfnl_unlock(); |
| return -EBUSY; |
| } |
| subsys_table[n->subsys_id] = n; |
| nfnl_unlock(); |
| |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(nfnetlink_subsys_register); |
| |
| int nfnetlink_subsys_unregister(struct nfnetlink_subsystem *n) |
| { |
| nfnl_lock(); |
| subsys_table[n->subsys_id] = NULL; |
| nfnl_unlock(); |
| |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister); |
| |
| static inline struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t type) |
| { |
| u_int8_t subsys_id = NFNL_SUBSYS_ID(type); |
| |
| if (subsys_id >= NFNL_SUBSYS_COUNT) |
| return NULL; |
| |
| return subsys_table[subsys_id]; |
| } |
| |
| static inline struct nfnl_callback * |
| nfnetlink_find_client(u_int16_t type, struct nfnetlink_subsystem *ss) |
| { |
| u_int8_t cb_id = NFNL_MSG_TYPE(type); |
| |
| if (cb_id >= ss->cb_count) |
| return NULL; |
| |
| return &ss->cb[cb_id]; |
| } |
| |
| void __nfa_fill(struct sk_buff *skb, int attrtype, int attrlen, |
| const void *data) |
| { |
| struct nfattr *nfa; |
| int size = NFA_LENGTH(attrlen); |
| |
| nfa = (struct nfattr *)skb_put(skb, NFA_ALIGN(size)); |
| nfa->nfa_type = attrtype; |
| nfa->nfa_len = size; |
| memcpy(NFA_DATA(nfa), data, attrlen); |
| memset(NFA_DATA(nfa) + attrlen, 0, NFA_ALIGN(size) - size); |
| } |
| EXPORT_SYMBOL_GPL(__nfa_fill); |
| |
| void nfattr_parse(struct nfattr *tb[], int maxattr, struct nfattr *nfa, int len) |
| { |
| memset(tb, 0, sizeof(struct nfattr *) * maxattr); |
| |
| while (NFA_OK(nfa, len)) { |
| unsigned flavor = NFA_TYPE(nfa); |
| if (flavor && flavor <= maxattr) |
| tb[flavor-1] = nfa; |
| nfa = NFA_NEXT(nfa, len); |
| } |
| } |
| EXPORT_SYMBOL_GPL(nfattr_parse); |
| |
| /** |
| * nfnetlink_check_attributes - check and parse nfnetlink attributes |
| * |
| * subsys: nfnl subsystem for which this message is to be parsed |
| * nlmsghdr: netlink message to be checked/parsed |
| * cda: array of pointers, needs to be at least subsys->attr_count big |
| * |
| */ |
| static int |
| nfnetlink_check_attributes(struct nfnetlink_subsystem *subsys, |
| struct nlmsghdr *nlh, struct nfattr *cda[]) |
| { |
| int min_len = NLMSG_SPACE(sizeof(struct nfgenmsg)); |
| u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type); |
| u_int16_t attr_count = subsys->cb[cb_id].attr_count; |
| |
| /* check attribute lengths. */ |
| if (likely(nlh->nlmsg_len > min_len)) { |
| struct nfattr *attr = NFM_NFA(NLMSG_DATA(nlh)); |
| int attrlen = nlh->nlmsg_len - NLMSG_ALIGN(min_len); |
| nfattr_parse(cda, attr_count, attr, attrlen); |
| } |
| |
| /* implicit: if nlmsg_len == min_len, we return 0, and an empty |
| * (zeroed) cda[] array. The message is valid, but empty. */ |
| |
| return 0; |
| } |
| |
| int nfnetlink_has_listeners(unsigned int group) |
| { |
| return netlink_has_listeners(nfnl, group); |
| } |
| EXPORT_SYMBOL_GPL(nfnetlink_has_listeners); |
| |
| int nfnetlink_send(struct sk_buff *skb, u32 pid, unsigned group, int echo) |
| { |
| int err = 0; |
| |
| NETLINK_CB(skb).dst_group = group; |
| if (echo) |
| atomic_inc(&skb->users); |
| netlink_broadcast(nfnl, skb, pid, group, gfp_any()); |
| if (echo) |
| err = netlink_unicast(nfnl, skb, pid, MSG_DONTWAIT); |
| |
| return err; |
| } |
| EXPORT_SYMBOL_GPL(nfnetlink_send); |
| |
| int nfnetlink_unicast(struct sk_buff *skb, u_int32_t pid, int flags) |
| { |
| return netlink_unicast(nfnl, skb, pid, flags); |
| } |
| EXPORT_SYMBOL_GPL(nfnetlink_unicast); |
| |
| /* Process one complete nfnetlink message. */ |
| static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh) |
| { |
| struct nfnl_callback *nc; |
| struct nfnetlink_subsystem *ss; |
| int type, err; |
| |
| if (security_netlink_recv(skb, CAP_NET_ADMIN)) |
| return -EPERM; |
| |
| /* Only requests are handled by kernel now. */ |
| if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) |
| return 0; |
| |
| /* All the messages must at least contain nfgenmsg */ |
| if (nlh->nlmsg_len < NLMSG_SPACE(sizeof(struct nfgenmsg))) |
| return 0; |
| |
| type = nlh->nlmsg_type; |
| ss = nfnetlink_get_subsys(type); |
| if (!ss) { |
| #ifdef CONFIG_KMOD |
| /* don't call nfnl_unlock, since it would reenter |
| * with further packet processing */ |
| __nfnl_unlock(); |
| request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type)); |
| nfnl_lock(); |
| ss = nfnetlink_get_subsys(type); |
| if (!ss) |
| #endif |
| return -EINVAL; |
| } |
| |
| nc = nfnetlink_find_client(type, ss); |
| if (!nc) |
| return -EINVAL; |
| |
| { |
| u_int16_t attr_count = |
| ss->cb[NFNL_MSG_TYPE(nlh->nlmsg_type)].attr_count; |
| struct nfattr *cda[attr_count]; |
| |
| memset(cda, 0, sizeof(struct nfattr *) * attr_count); |
| |
| err = nfnetlink_check_attributes(ss, nlh, cda); |
| if (err < 0) |
| return err; |
| return nc->call(nfnl, skb, nlh, cda); |
| } |
| } |
| |
| static void nfnetlink_rcv(struct sock *sk, int len) |
| { |
| unsigned int qlen = 0; |
| |
| do { |
| if (nfnl_trylock()) |
| return; |
| netlink_run_queue(sk, &qlen, nfnetlink_rcv_msg); |
| __nfnl_unlock(); |
| } while (qlen); |
| } |
| |
| static void __exit nfnetlink_exit(void) |
| { |
| printk("Removing netfilter NETLINK layer.\n"); |
| sock_release(nfnl->sk_socket); |
| return; |
| } |
| |
| static int __init nfnetlink_init(void) |
| { |
| printk("Netfilter messages via NETLINK v%s.\n", nfversion); |
| |
| nfnl = netlink_kernel_create(NETLINK_NETFILTER, NFNLGRP_MAX, |
| nfnetlink_rcv, THIS_MODULE); |
| if (!nfnl) { |
| printk(KERN_ERR "cannot initialize nfnetlink!\n"); |
| return -1; |
| } |
| |
| return 0; |
| } |
| |
| module_init(nfnetlink_init); |
| module_exit(nfnetlink_exit); |