diff options
Diffstat (limited to 'net/netfilter/nfnetlink.c')
-rw-r--r-- | net/netfilter/nfnetlink.c | 244 |
1 files changed, 244 insertions, 0 deletions
diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c new file mode 100644 index 00000000..e6ddde16 --- /dev/null +++ b/net/netfilter/nfnetlink.c @@ -0,0 +1,244 @@ +/* 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/string.h> +#include <linux/sockios.h> +#include <linux/net.h> +#include <linux/skbuff.h> +#include <asm/uaccess.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 const struct nfnetlink_subsystem __rcu *subsys_table[NFNL_SUBSYS_COUNT]; +static DEFINE_MUTEX(nfnl_mutex); + +void nfnl_lock(void) +{ + mutex_lock(&nfnl_mutex); +} +EXPORT_SYMBOL_GPL(nfnl_lock); + +void nfnl_unlock(void) +{ + mutex_unlock(&nfnl_mutex); +} +EXPORT_SYMBOL_GPL(nfnl_unlock); + +int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n) +{ + nfnl_lock(); + if (subsys_table[n->subsys_id]) { + nfnl_unlock(); + return -EBUSY; + } + rcu_assign_pointer(subsys_table[n->subsys_id], n); + nfnl_unlock(); + + return 0; +} +EXPORT_SYMBOL_GPL(nfnetlink_subsys_register); + +int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n) +{ + nfnl_lock(); + subsys_table[n->subsys_id] = NULL; + nfnl_unlock(); + synchronize_rcu(); + return 0; +} +EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister); + +static inline const 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 rcu_dereference(subsys_table[subsys_id]); +} + +static inline const struct nfnl_callback * +nfnetlink_find_client(u_int16_t type, const 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]; +} + +int nfnetlink_has_listeners(struct net *net, unsigned int group) +{ + return netlink_has_listeners(net->nfnl, group); +} +EXPORT_SYMBOL_GPL(nfnetlink_has_listeners); + +int nfnetlink_send(struct sk_buff *skb, struct net *net, u32 pid, + unsigned group, int echo, gfp_t flags) +{ + return nlmsg_notify(net->nfnl, skb, pid, group, echo, flags); +} +EXPORT_SYMBOL_GPL(nfnetlink_send); + +int nfnetlink_set_err(struct net *net, u32 pid, u32 group, int error) +{ + return netlink_set_err(net->nfnl, pid, group, error); +} +EXPORT_SYMBOL_GPL(nfnetlink_set_err); + +int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u_int32_t pid, int flags) +{ + return netlink_unicast(net->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 net *net = sock_net(skb->sk); + const struct nfnl_callback *nc; + const struct nfnetlink_subsystem *ss; + int type, err; + + if (!capable(CAP_NET_ADMIN)) + return -EPERM; + + /* All the messages must at least contain nfgenmsg */ + if (nlh->nlmsg_len < NLMSG_LENGTH(sizeof(struct nfgenmsg))) + return 0; + + type = nlh->nlmsg_type; +replay: + rcu_read_lock(); + ss = nfnetlink_get_subsys(type); + if (!ss) { +#ifdef CONFIG_MODULES + rcu_read_unlock(); + request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type)); + rcu_read_lock(); + ss = nfnetlink_get_subsys(type); + if (!ss) +#endif + { + rcu_read_unlock(); + return -EINVAL; + } + } + + nc = nfnetlink_find_client(type, ss); + if (!nc) { + rcu_read_unlock(); + return -EINVAL; + } + + { + int min_len = NLMSG_SPACE(sizeof(struct nfgenmsg)); + u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type); + struct nlattr *cda[ss->cb[cb_id].attr_count + 1]; + struct nlattr *attr = (void *)nlh + min_len; + int attrlen = nlh->nlmsg_len - min_len; + + err = nla_parse(cda, ss->cb[cb_id].attr_count, + attr, attrlen, ss->cb[cb_id].policy); + if (err < 0) + return err; + + if (nc->call_rcu) { + err = nc->call_rcu(net->nfnl, skb, nlh, + (const struct nlattr **)cda); + rcu_read_unlock(); + } else { + rcu_read_unlock(); + nfnl_lock(); + if (rcu_dereference_protected( + subsys_table[NFNL_SUBSYS_ID(type)], + lockdep_is_held(&nfnl_mutex)) != ss || + nfnetlink_find_client(type, ss) != nc) + err = -EAGAIN; + else + err = nc->call(net->nfnl, skb, nlh, + (const struct nlattr **)cda); + nfnl_unlock(); + } + if (err == -EAGAIN) + goto replay; + return err; + } +} + +static void nfnetlink_rcv(struct sk_buff *skb) +{ + netlink_rcv_skb(skb, &nfnetlink_rcv_msg); +} + +static int __net_init nfnetlink_net_init(struct net *net) +{ + struct sock *nfnl; + + nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, NFNLGRP_MAX, + nfnetlink_rcv, NULL, THIS_MODULE); + if (!nfnl) + return -ENOMEM; + net->nfnl_stash = nfnl; + rcu_assign_pointer(net->nfnl, nfnl); + return 0; +} + +static void __net_exit nfnetlink_net_exit_batch(struct list_head *net_exit_list) +{ + struct net *net; + + list_for_each_entry(net, net_exit_list, exit_list) + RCU_INIT_POINTER(net->nfnl, NULL); + synchronize_net(); + list_for_each_entry(net, net_exit_list, exit_list) + netlink_kernel_release(net->nfnl_stash); +} + +static struct pernet_operations nfnetlink_net_ops = { + .init = nfnetlink_net_init, + .exit_batch = nfnetlink_net_exit_batch, +}; + +static int __init nfnetlink_init(void) +{ + pr_info("Netfilter messages via NETLINK v%s.\n", nfversion); + return register_pernet_subsys(&nfnetlink_net_ops); +} + +static void __exit nfnetlink_exit(void) +{ + pr_info("Removing netfilter NETLINK layer.\n"); + unregister_pernet_subsys(&nfnetlink_net_ops); +} +module_init(nfnetlink_init); +module_exit(nfnetlink_exit); |