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![Fernando Fernandez Mancera](/assets/img/avatar_default.png)
Add nf_osf_ttl() and nf_osf_match() into nf_osf.c to prepare for nf_tables support. Signed-off-by: Fernando Fernandez Mancera <ffmancera@riseup.net> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
236 lines
5.5 KiB
C
236 lines
5.5 KiB
C
/*
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* Copyright (c) 2003+ Evgeniy Polyakov <zbr@ioremap.net>
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*
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <http://www.gnu.org/licenses/>.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/capability.h>
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#include <linux/if.h>
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#include <linux/inetdevice.h>
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#include <linux/ip.h>
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#include <linux/list.h>
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#include <linux/rculist.h>
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#include <linux/skbuff.h>
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#include <linux/slab.h>
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#include <linux/tcp.h>
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#include <net/ip.h>
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#include <net/tcp.h>
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#include <linux/netfilter/nfnetlink.h>
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#include <linux/netfilter/x_tables.h>
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#include <net/netfilter/nf_log.h>
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#include <linux/netfilter/xt_osf.h>
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/*
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* Indexed by dont-fragment bit.
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* It is the only constant value in the fingerprint.
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*/
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static struct list_head xt_osf_fingers[2];
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static const struct nla_policy xt_osf_policy[OSF_ATTR_MAX + 1] = {
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[OSF_ATTR_FINGER] = { .len = sizeof(struct xt_osf_user_finger) },
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};
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static int xt_osf_add_callback(struct net *net, struct sock *ctnl,
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struct sk_buff *skb, const struct nlmsghdr *nlh,
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const struct nlattr * const osf_attrs[],
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struct netlink_ext_ack *extack)
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{
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struct xt_osf_user_finger *f;
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struct xt_osf_finger *kf = NULL, *sf;
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int err = 0;
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if (!capable(CAP_NET_ADMIN))
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return -EPERM;
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if (!osf_attrs[OSF_ATTR_FINGER])
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return -EINVAL;
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if (!(nlh->nlmsg_flags & NLM_F_CREATE))
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return -EINVAL;
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f = nla_data(osf_attrs[OSF_ATTR_FINGER]);
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kf = kmalloc(sizeof(struct xt_osf_finger), GFP_KERNEL);
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if (!kf)
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return -ENOMEM;
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memcpy(&kf->finger, f, sizeof(struct xt_osf_user_finger));
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list_for_each_entry(sf, &xt_osf_fingers[!!f->df], finger_entry) {
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if (memcmp(&sf->finger, f, sizeof(struct xt_osf_user_finger)))
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continue;
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kfree(kf);
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kf = NULL;
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if (nlh->nlmsg_flags & NLM_F_EXCL)
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err = -EEXIST;
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break;
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}
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/*
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* We are protected by nfnl mutex.
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*/
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if (kf)
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list_add_tail_rcu(&kf->finger_entry, &xt_osf_fingers[!!f->df]);
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return err;
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}
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static int xt_osf_remove_callback(struct net *net, struct sock *ctnl,
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struct sk_buff *skb,
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const struct nlmsghdr *nlh,
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const struct nlattr * const osf_attrs[],
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struct netlink_ext_ack *extack)
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{
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struct xt_osf_user_finger *f;
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struct xt_osf_finger *sf;
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int err = -ENOENT;
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if (!capable(CAP_NET_ADMIN))
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return -EPERM;
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if (!osf_attrs[OSF_ATTR_FINGER])
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return -EINVAL;
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f = nla_data(osf_attrs[OSF_ATTR_FINGER]);
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list_for_each_entry(sf, &xt_osf_fingers[!!f->df], finger_entry) {
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if (memcmp(&sf->finger, f, sizeof(struct xt_osf_user_finger)))
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continue;
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/*
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* We are protected by nfnl mutex.
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*/
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list_del_rcu(&sf->finger_entry);
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kfree_rcu(sf, rcu_head);
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err = 0;
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break;
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}
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return err;
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}
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static const struct nfnl_callback xt_osf_nfnetlink_callbacks[OSF_MSG_MAX] = {
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[OSF_MSG_ADD] = {
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.call = xt_osf_add_callback,
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.attr_count = OSF_ATTR_MAX,
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.policy = xt_osf_policy,
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},
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[OSF_MSG_REMOVE] = {
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.call = xt_osf_remove_callback,
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.attr_count = OSF_ATTR_MAX,
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.policy = xt_osf_policy,
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},
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};
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static const struct nfnetlink_subsystem xt_osf_nfnetlink = {
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.name = "osf",
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.subsys_id = NFNL_SUBSYS_OSF,
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.cb_count = OSF_MSG_MAX,
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.cb = xt_osf_nfnetlink_callbacks,
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};
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static bool
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xt_osf_match_packet(const struct sk_buff *skb, struct xt_action_param *p)
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{
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const struct xt_osf_info *info = p->matchinfo;
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struct net *net = xt_net(p);
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if (!info)
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return false;
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return nf_osf_match(skb, xt_family(p), xt_hooknum(p), xt_in(p),
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xt_out(p), info, net, xt_osf_fingers);
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}
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static struct xt_match xt_osf_match = {
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.name = "osf",
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.revision = 0,
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.family = NFPROTO_IPV4,
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.proto = IPPROTO_TCP,
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.hooks = (1 << NF_INET_LOCAL_IN) |
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(1 << NF_INET_PRE_ROUTING) |
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(1 << NF_INET_FORWARD),
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.match = xt_osf_match_packet,
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.matchsize = sizeof(struct xt_osf_info),
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.me = THIS_MODULE,
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};
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static int __init xt_osf_init(void)
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{
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int err = -EINVAL;
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int i;
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for (i=0; i<ARRAY_SIZE(xt_osf_fingers); ++i)
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INIT_LIST_HEAD(&xt_osf_fingers[i]);
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err = nfnetlink_subsys_register(&xt_osf_nfnetlink);
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if (err < 0) {
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pr_err("Failed to register OSF nsfnetlink helper (%d)\n", err);
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goto err_out_exit;
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}
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err = xt_register_match(&xt_osf_match);
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if (err) {
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pr_err("Failed to register OS fingerprint "
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"matching module (%d)\n", err);
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goto err_out_remove;
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}
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return 0;
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err_out_remove:
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nfnetlink_subsys_unregister(&xt_osf_nfnetlink);
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err_out_exit:
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return err;
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}
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static void __exit xt_osf_fini(void)
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{
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struct xt_osf_finger *f;
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int i;
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nfnetlink_subsys_unregister(&xt_osf_nfnetlink);
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xt_unregister_match(&xt_osf_match);
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rcu_read_lock();
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for (i=0; i<ARRAY_SIZE(xt_osf_fingers); ++i) {
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list_for_each_entry_rcu(f, &xt_osf_fingers[i], finger_entry) {
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list_del_rcu(&f->finger_entry);
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kfree_rcu(f, rcu_head);
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}
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}
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rcu_read_unlock();
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rcu_barrier();
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}
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module_init(xt_osf_init);
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module_exit(xt_osf_fini);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");
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MODULE_DESCRIPTION("Passive OS fingerprint matching.");
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MODULE_ALIAS("ipt_osf");
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MODULE_ALIAS("ip6t_osf");
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MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_OSF);
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