diff options
Diffstat (limited to 'net/netfilter/nfnetlink.c')
| -rw-r--r-- | net/netfilter/nfnetlink.c | 468 |
1 files changed, 468 insertions, 0 deletions
diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c new file mode 100644 index 00000000000..c138b8fbe28 --- /dev/null +++ b/net/netfilter/nfnetlink.c @@ -0,0 +1,468 @@ +/* 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 <linux/init.h> + +#include <net/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 { + struct mutex mutex; + const struct nfnetlink_subsystem __rcu *subsys; +} table[NFNL_SUBSYS_COUNT]; + +static const int nfnl_group2type[NFNLGRP_MAX+1] = { + [NFNLGRP_CONNTRACK_NEW] = NFNL_SUBSYS_CTNETLINK, + [NFNLGRP_CONNTRACK_UPDATE] = NFNL_SUBSYS_CTNETLINK, + [NFNLGRP_CONNTRACK_DESTROY] = NFNL_SUBSYS_CTNETLINK, + [NFNLGRP_CONNTRACK_EXP_NEW] = NFNL_SUBSYS_CTNETLINK_EXP, + [NFNLGRP_CONNTRACK_EXP_UPDATE] = NFNL_SUBSYS_CTNETLINK_EXP, + [NFNLGRP_CONNTRACK_EXP_DESTROY] = NFNL_SUBSYS_CTNETLINK_EXP, +}; + +void nfnl_lock(__u8 subsys_id) +{ + mutex_lock(&table[subsys_id].mutex); +} +EXPORT_SYMBOL_GPL(nfnl_lock); + +void nfnl_unlock(__u8 subsys_id) +{ + mutex_unlock(&table[subsys_id].mutex); +} +EXPORT_SYMBOL_GPL(nfnl_unlock); + +#ifdef CONFIG_PROVE_LOCKING +int lockdep_nfnl_is_held(u8 subsys_id) +{ + return lockdep_is_held(&table[subsys_id].mutex); +} +EXPORT_SYMBOL_GPL(lockdep_nfnl_is_held); +#endif + +int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n) +{ + nfnl_lock(n->subsys_id); + if (table[n->subsys_id].subsys) { + nfnl_unlock(n->subsys_id); + return -EBUSY; + } + rcu_assign_pointer(table[n->subsys_id].subsys, n); + nfnl_unlock(n->subsys_id); + + return 0; +} +EXPORT_SYMBOL_GPL(nfnetlink_subsys_register); + +int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n) +{ + nfnl_lock(n->subsys_id); + table[n->subsys_id].subsys = NULL; + nfnl_unlock(n->subsys_id); + 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(table[subsys_id].subsys); +} + +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); + +struct sk_buff *nfnetlink_alloc_skb(struct net *net, unsigned int size, + u32 dst_portid, gfp_t gfp_mask) +{ + return netlink_alloc_skb(net->nfnl, size, dst_portid, gfp_mask); +} +EXPORT_SYMBOL_GPL(nfnetlink_alloc_skb); + +int nfnetlink_send(struct sk_buff *skb, struct net *net, u32 portid, + unsigned int group, int echo, gfp_t flags) +{ + return nlmsg_notify(net->nfnl, skb, portid, group, echo, flags); +} +EXPORT_SYMBOL_GPL(nfnetlink_send); + +int nfnetlink_set_err(struct net *net, u32 portid, u32 group, int error) +{ + return netlink_set_err(net->nfnl, portid, group, error); +} +EXPORT_SYMBOL_GPL(nfnetlink_set_err); + +int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u32 portid, + int flags) +{ + return netlink_unicast(net->nfnl, skb, portid, 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; + + /* All the messages must at least contain nfgenmsg */ + if (nlmsg_len(nlh) < 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_total_size(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; + __u8 subsys_id = NFNL_SUBSYS_ID(type); + + err = nla_parse(cda, ss->cb[cb_id].attr_count, + attr, attrlen, ss->cb[cb_id].policy); + if (err < 0) { + rcu_read_unlock(); + 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(subsys_id); + if (rcu_dereference_protected(table[subsys_id].subsys, + lockdep_is_held(&table[subsys_id].mutex)) != ss || + nfnetlink_find_client(type, ss) != nc) + err = -EAGAIN; + else if (nc->call) + err = nc->call(net->nfnl, skb, nlh, + (const struct nlattr **)cda); + else + err = -EINVAL; + nfnl_unlock(subsys_id); + } + if (err == -EAGAIN) + goto replay; + return err; + } +} + +static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh, + u_int16_t subsys_id) +{ + struct sk_buff *nskb, *oskb = skb; + struct net *net = sock_net(skb->sk); + const struct nfnetlink_subsystem *ss; + const struct nfnl_callback *nc; + bool success = true, done = false; + int err; + + if (subsys_id >= NFNL_SUBSYS_COUNT) + return netlink_ack(skb, nlh, -EINVAL); +replay: + nskb = netlink_skb_clone(oskb, GFP_KERNEL); + if (!nskb) + return netlink_ack(oskb, nlh, -ENOMEM); + + nskb->sk = oskb->sk; + skb = nskb; + + nfnl_lock(subsys_id); + ss = rcu_dereference_protected(table[subsys_id].subsys, + lockdep_is_held(&table[subsys_id].mutex)); + if (!ss) { +#ifdef CONFIG_MODULES + nfnl_unlock(subsys_id); + request_module("nfnetlink-subsys-%d", subsys_id); + nfnl_lock(subsys_id); + ss = rcu_dereference_protected(table[subsys_id].subsys, + lockdep_is_held(&table[subsys_id].mutex)); + if (!ss) +#endif + { + nfnl_unlock(subsys_id); + netlink_ack(skb, nlh, -EOPNOTSUPP); + return kfree_skb(nskb); + } + } + + if (!ss->commit || !ss->abort) { + nfnl_unlock(subsys_id); + netlink_ack(skb, nlh, -EOPNOTSUPP); + return kfree_skb(skb); + } + + while (skb->len >= nlmsg_total_size(0)) { + int msglen, type; + + nlh = nlmsg_hdr(skb); + err = 0; + + if (nlh->nlmsg_len < NLMSG_HDRLEN) { + err = -EINVAL; + goto ack; + } + + /* Only requests are handled by the kernel */ + if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) { + err = -EINVAL; + goto ack; + } + + type = nlh->nlmsg_type; + if (type == NFNL_MSG_BATCH_BEGIN) { + /* Malformed: Batch begin twice */ + success = false; + goto done; + } else if (type == NFNL_MSG_BATCH_END) { + done = true; + goto done; + } else if (type < NLMSG_MIN_TYPE) { + err = -EINVAL; + goto ack; + } + + /* We only accept a batch with messages for the same + * subsystem. + */ + if (NFNL_SUBSYS_ID(type) != subsys_id) { + err = -EINVAL; + goto ack; + } + + nc = nfnetlink_find_client(type, ss); + if (!nc) { + err = -EINVAL; + goto ack; + } + + { + int min_len = nlmsg_total_size(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) + goto ack; + + if (nc->call_batch) { + err = nc->call_batch(net->nfnl, skb, nlh, + (const struct nlattr **)cda); + } + + /* The lock was released to autoload some module, we + * have to abort and start from scratch using the + * original skb. + */ + if (err == -EAGAIN) { + ss->abort(skb); + nfnl_unlock(subsys_id); + kfree_skb(nskb); + goto replay; + } + } +ack: + if (nlh->nlmsg_flags & NLM_F_ACK || err) { + /* We don't stop processing the batch on errors, thus, + * userspace gets all the errors that the batch + * triggers. + */ + netlink_ack(skb, nlh, err); + if (err) + success = false; + } + + msglen = NLMSG_ALIGN(nlh->nlmsg_len); + if (msglen > skb->len) + msglen = skb->len; + skb_pull(skb, msglen); + } +done: + if (success && done) + ss->commit(skb); + else + ss->abort(skb); + + nfnl_unlock(subsys_id); + kfree_skb(nskb); +} + +static void nfnetlink_rcv(struct sk_buff *skb) +{ + struct nlmsghdr *nlh = nlmsg_hdr(skb); + int msglen; + + if (nlh->nlmsg_len < NLMSG_HDRLEN || + skb->len < nlh->nlmsg_len) + return; + + if (!netlink_net_capable(skb, CAP_NET_ADMIN)) { + netlink_ack(skb, nlh, -EPERM); + return; + } + + if (nlh->nlmsg_type == NFNL_MSG_BATCH_BEGIN) { + struct nfgenmsg *nfgenmsg; + + msglen = NLMSG_ALIGN(nlh->nlmsg_len); + if (msglen > skb->len) + msglen = skb->len; + + if (nlh->nlmsg_len < NLMSG_HDRLEN || + skb->len < NLMSG_HDRLEN + sizeof(struct nfgenmsg)) + return; + + nfgenmsg = nlmsg_data(nlh); + skb_pull(skb, msglen); + nfnetlink_rcv_batch(skb, nlh, nfgenmsg->res_id); + } else { + netlink_rcv_skb(skb, &nfnetlink_rcv_msg); + } +} + +#ifdef CONFIG_MODULES +static int nfnetlink_bind(int group) +{ + const struct nfnetlink_subsystem *ss; + int type = nfnl_group2type[group]; + + rcu_read_lock(); + ss = nfnetlink_get_subsys(type); + rcu_read_unlock(); + if (!ss) + request_module("nfnetlink-subsys-%d", type); + return 0; +} +#endif + +static int __net_init nfnetlink_net_init(struct net *net) +{ + struct sock *nfnl; + struct netlink_kernel_cfg cfg = { + .groups = NFNLGRP_MAX, + .input = nfnetlink_rcv, +#ifdef CONFIG_MODULES + .bind = nfnetlink_bind, +#endif + }; + + nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, &cfg); + 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) +{ + int i; + + for (i=0; i<NFNL_SUBSYS_COUNT; i++) + mutex_init(&table[i].mutex); + + 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); |