![Pablo Neira Ayuso](/assets/img/avatar_default.png)
With this patch, nfnetlink returns -ENOMEM instead of -EPERM if we fail to create the nfnetlink netlink socket during the module loading. This is exactly what rtnetlink does in this case. Ideally, it would be better if we propagate the error that has happened in netlink_kernel_create(), however, this function still does not implement this yet. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Signed-off-by: Patrick McHardy <kaber@trash.net>
214 lines
5 KiB
C
214 lines
5 KiB
C
/* Netfilter messages via netlink socket. Allows for user space
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* protocol helpers and general trouble making from userspace.
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*
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* (C) 2001 by Jay Schulist <jschlst@samba.org>,
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* (C) 2002-2005 by Harald Welte <laforge@gnumonks.org>
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* (C) 2005,2007 by Pablo Neira Ayuso <pablo@netfilter.org>
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*
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* Initial netfilter messages via netlink development funded and
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* generally made possible by Network Robots, Inc. (www.networkrobots.com)
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*
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* Further development of this code funded by Astaro AG (http://www.astaro.com)
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*
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* This software may be used and distributed according to the terms
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* of the GNU General Public License, incorporated herein by reference.
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*/
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/socket.h>
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#include <linux/kernel.h>
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#include <linux/major.h>
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#include <linux/timer.h>
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#include <linux/string.h>
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#include <linux/sockios.h>
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#include <linux/net.h>
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#include <linux/fcntl.h>
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#include <linux/skbuff.h>
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#include <asm/uaccess.h>
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#include <asm/system.h>
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#include <net/sock.h>
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#include <net/netlink.h>
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#include <linux/init.h>
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#include <linux/netlink.h>
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#include <linux/netfilter/nfnetlink.h>
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
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MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER);
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static char __initdata nfversion[] = "0.30";
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static struct sock *nfnl = NULL;
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static const struct nfnetlink_subsystem *subsys_table[NFNL_SUBSYS_COUNT];
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static DEFINE_MUTEX(nfnl_mutex);
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void nfnl_lock(void)
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{
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mutex_lock(&nfnl_mutex);
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}
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EXPORT_SYMBOL_GPL(nfnl_lock);
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void nfnl_unlock(void)
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{
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mutex_unlock(&nfnl_mutex);
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}
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EXPORT_SYMBOL_GPL(nfnl_unlock);
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int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n)
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{
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nfnl_lock();
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if (subsys_table[n->subsys_id]) {
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nfnl_unlock();
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return -EBUSY;
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}
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subsys_table[n->subsys_id] = n;
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nfnl_unlock();
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return 0;
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}
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EXPORT_SYMBOL_GPL(nfnetlink_subsys_register);
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int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n)
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{
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nfnl_lock();
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subsys_table[n->subsys_id] = NULL;
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nfnl_unlock();
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return 0;
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}
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EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister);
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static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t type)
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{
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u_int8_t subsys_id = NFNL_SUBSYS_ID(type);
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if (subsys_id >= NFNL_SUBSYS_COUNT)
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return NULL;
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return subsys_table[subsys_id];
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}
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static inline const struct nfnl_callback *
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nfnetlink_find_client(u_int16_t type, const struct nfnetlink_subsystem *ss)
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{
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u_int8_t cb_id = NFNL_MSG_TYPE(type);
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if (cb_id >= ss->cb_count)
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return NULL;
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return &ss->cb[cb_id];
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}
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int nfnetlink_has_listeners(unsigned int group)
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{
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return netlink_has_listeners(nfnl, group);
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}
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EXPORT_SYMBOL_GPL(nfnetlink_has_listeners);
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int nfnetlink_send(struct sk_buff *skb, u32 pid, unsigned group, int echo)
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{
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return nlmsg_notify(nfnl, skb, pid, group, echo, gfp_any());
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}
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EXPORT_SYMBOL_GPL(nfnetlink_send);
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void nfnetlink_set_err(u32 pid, u32 group, int error)
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{
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netlink_set_err(nfnl, pid, group, error);
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}
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EXPORT_SYMBOL_GPL(nfnetlink_set_err);
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int nfnetlink_unicast(struct sk_buff *skb, u_int32_t pid, int flags)
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{
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return netlink_unicast(nfnl, skb, pid, flags);
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}
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EXPORT_SYMBOL_GPL(nfnetlink_unicast);
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/* Process one complete nfnetlink message. */
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static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
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{
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const struct nfnl_callback *nc;
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const struct nfnetlink_subsystem *ss;
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int type, err;
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if (security_netlink_recv(skb, CAP_NET_ADMIN))
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return -EPERM;
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/* All the messages must at least contain nfgenmsg */
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if (nlh->nlmsg_len < NLMSG_SPACE(sizeof(struct nfgenmsg)))
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return 0;
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type = nlh->nlmsg_type;
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replay:
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ss = nfnetlink_get_subsys(type);
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if (!ss) {
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#ifdef CONFIG_MODULES
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nfnl_unlock();
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request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type));
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nfnl_lock();
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ss = nfnetlink_get_subsys(type);
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if (!ss)
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#endif
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return -EINVAL;
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}
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nc = nfnetlink_find_client(type, ss);
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if (!nc)
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return -EINVAL;
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{
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int min_len = NLMSG_SPACE(sizeof(struct nfgenmsg));
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u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
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u_int16_t attr_count = ss->cb[cb_id].attr_count;
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struct nlattr *cda[attr_count+1];
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if (likely(nlh->nlmsg_len >= min_len)) {
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struct nlattr *attr = (void *)nlh + NLMSG_ALIGN(min_len);
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int attrlen = nlh->nlmsg_len - NLMSG_ALIGN(min_len);
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err = nla_parse(cda, attr_count, attr, attrlen,
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ss->cb[cb_id].policy);
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if (err < 0)
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return err;
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} else
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return -EINVAL;
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err = nc->call(nfnl, skb, nlh, cda);
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if (err == -EAGAIN)
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goto replay;
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return err;
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}
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}
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static void nfnetlink_rcv(struct sk_buff *skb)
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{
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nfnl_lock();
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netlink_rcv_skb(skb, &nfnetlink_rcv_msg);
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nfnl_unlock();
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}
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static void __exit nfnetlink_exit(void)
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{
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printk("Removing netfilter NETLINK layer.\n");
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netlink_kernel_release(nfnl);
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return;
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}
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static int __init nfnetlink_init(void)
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{
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printk("Netfilter messages via NETLINK v%s.\n", nfversion);
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nfnl = netlink_kernel_create(&init_net, NETLINK_NETFILTER, NFNLGRP_MAX,
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nfnetlink_rcv, NULL, THIS_MODULE);
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if (!nfnl) {
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printk(KERN_ERR "cannot initialize nfnetlink!\n");
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return -ENOMEM;
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}
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return 0;
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}
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module_init(nfnetlink_init);
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module_exit(nfnetlink_exit);
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