--- /dev/null
+/* 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,
+ [NFNLGRP_NFTABLES] = NFNL_SUBSYS_NFTABLES,
+ [NFNLGRP_ACCT_QUOTA] = NFNL_SUBSYS_ACCT,
+};
+
+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;
+ }
+}
+
+struct nfnl_err {
+ struct list_head head;
+ struct nlmsghdr *nlh;
+ int err;
+};
+
+static int nfnl_err_add(struct list_head *list, struct nlmsghdr *nlh, int err)
+{
+ struct nfnl_err *nfnl_err;
+
+ nfnl_err = kmalloc(sizeof(struct nfnl_err), GFP_KERNEL);
+ if (nfnl_err == NULL)
+ return -ENOMEM;
+
+ nfnl_err->nlh = nlh;
+ nfnl_err->err = err;
+ list_add_tail(&nfnl_err->head, list);
+
+ return 0;
+}
+
+static void nfnl_err_del(struct nfnl_err *nfnl_err)
+{
+ list_del(&nfnl_err->head);
+ kfree(nfnl_err);
+}
+
+static void nfnl_err_reset(struct list_head *err_list)
+{
+ struct nfnl_err *nfnl_err, *next;
+
+ list_for_each_entry_safe(nfnl_err, next, err_list, head)
+ nfnl_err_del(nfnl_err);
+}
+
+static void nfnl_err_deliver(struct list_head *err_list, struct sk_buff *skb)
+{
+ struct nfnl_err *nfnl_err, *next;
+
+ list_for_each_entry_safe(nfnl_err, next, err_list, head) {
+ netlink_ack(skb, nfnl_err->nlh, nfnl_err->err);
+ nfnl_err_del(nfnl_err);
+ }
+}
+
+static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh,
+ u_int16_t subsys_id)
+{
+ struct sk_buff *oskb = skb;
+ struct net *net = sock_net(skb->sk);
+ const struct nfnetlink_subsystem *ss;
+ const struct nfnl_callback *nc;
+ bool success = true, done = false;
+ static LIST_HEAD(err_list);
+ int err;
+
+ if (subsys_id >= NFNL_SUBSYS_COUNT)
+ return netlink_ack(skb, nlh, -EINVAL);
+replay:
+ skb = netlink_skb_clone(oskb, GFP_KERNEL);
+ if (!skb)
+ return netlink_ack(oskb, nlh, -ENOMEM);
+
+ skb->sk = oskb->sk;
+
+ 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(skb);
+ }
+ }
+
+ 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 (nlmsg_len(nlh) < sizeof(struct nfgenmsg) ||
+ skb->len < nlh->nlmsg_len) {
+ 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 */
+ nfnl_err_reset(&err_list);
+ 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) {
+ nfnl_err_reset(&err_list);
+ ss->abort(oskb);
+ nfnl_unlock(subsys_id);
+ kfree_skb(skb);
+ goto replay;
+ }
+ }
+ack:
+ if (nlh->nlmsg_flags & NLM_F_ACK || err) {
+ /* Errors are delivered once the full batch has been
+ * processed, this avoids that the same error is
+ * reported several times when replaying the batch.
+ */
+ if (nfnl_err_add(&err_list, nlh, err) < 0) {
+ /* We failed to enqueue an error, reset the
+ * list of errors and send OOM to userspace
+ * pointing to the batch header.
+ */
+ nfnl_err_reset(&err_list);
+ netlink_ack(skb, nlmsg_hdr(oskb), -ENOMEM);
+ success = false;
+ goto done;
+ }
+ /* We don't stop processing the batch on errors, thus,
+ * userspace gets all the errors that the batch
+ * triggers.
+ */
+ 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(oskb);
+ else
+ ss->abort(oskb);
+
+ nfnl_err_deliver(&err_list, oskb);
+ nfnl_unlock(subsys_id);
+ kfree_skb(skb);
+}
+
+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(struct net *net, int group)
+{
+ const struct nfnetlink_subsystem *ss;
+ int type;
+
+ if (group <= NFNLGRP_NONE || group > NFNLGRP_MAX)
+ return 0;
+
+ 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 = NFNLGRP_NONE + 1; i <= NFNLGRP_MAX; i++)
+ BUG_ON(nfnl_group2type[i] == NFNL_SUBSYS_NONE);
+
+ 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);
Code Review / kvmfornfv.git / blobdiff