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Commit | Line | Data |
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2cb7cef9 BS |
1 | From: Jiri Bohac <jbohac@suse.cz> |
2 | Subject: connection tracking helper for SLP | |
3 | References: fate#301134 | |
4 | ||
5 | A simple connection tracking helper for SLP. Marks replies to a | |
6 | SLP broadcast query as ESTABLISHED to allow them to pass through the | |
7 | firewall. | |
8 | ||
9 | Signed-off-by: Jiri Bohac <jbohac@suse.cz> | |
10 | ||
11 | --- | |
12 | net/netfilter/Kconfig | 15 ++++ | |
13 | net/netfilter/Makefile | 1 | |
14 | net/netfilter/nf_conntrack_slp.c | 127 +++++++++++++++++++++++++++++++++++++++ | |
15 | 3 files changed, 143 insertions(+) | |
16 | ||
17 | --- a/net/netfilter/Kconfig | |
18 | +++ b/net/netfilter/Kconfig | |
19 | @@ -278,6 +278,21 @@ config NF_CONNTRACK_TFTP | |
20 | ||
21 | To compile it as a module, choose M here. If unsure, say N. | |
22 | ||
23 | +config NF_CONNTRACK_SLP | |
24 | + tristate "SLP protocol support" | |
25 | + depends on NF_CONNTRACK | |
26 | + depends on NETFILTER_ADVANCED | |
27 | + help | |
28 | + SLP queries are sometimes sent as broadcast messages from an | |
29 | + unprivileged port and responded to with unicast messages to the | |
30 | + same port. This make them hard to firewall properly because connection | |
31 | + tracking doesn't deal with broadcasts. This helper tracks locally | |
32 | + originating broadcast SLP queries and the corresponding | |
33 | + responses. It relies on correct IP address configuration, specifically | |
34 | + netmask and broadcast address. | |
35 | + | |
36 | + To compile it as a module, choose M here. If unsure, say N. | |
37 | + | |
38 | config NF_CT_NETLINK | |
39 | tristate 'Connection tracking netlink interface' | |
40 | depends on NF_CONNTRACK | |
41 | --- a/net/netfilter/Makefile | |
42 | +++ b/net/netfilter/Makefile | |
43 | @@ -33,6 +33,7 @@ obj-$(CONFIG_NF_CONNTRACK_PPTP) += nf_co | |
44 | obj-$(CONFIG_NF_CONNTRACK_SANE) += nf_conntrack_sane.o | |
45 | obj-$(CONFIG_NF_CONNTRACK_SIP) += nf_conntrack_sip.o | |
46 | obj-$(CONFIG_NF_CONNTRACK_TFTP) += nf_conntrack_tftp.o | |
47 | +obj-$(CONFIG_NF_CONNTRACK_SLP) += nf_conntrack_slp.o | |
48 | ||
49 | # generic X tables | |
50 | obj-$(CONFIG_NETFILTER_XTABLES) += x_tables.o xt_tcpudp.o | |
51 | --- /dev/null | |
52 | +++ b/net/netfilter/nf_conntrack_slp.c | |
53 | @@ -0,0 +1,127 @@ | |
54 | +/* | |
55 | + * NetBIOS name service broadcast connection tracking helper | |
56 | + * | |
57 | + * (c) 2007 Jiri Bohac <jbohac@suse.cz> | |
58 | + * (c) 2005 Patrick McHardy <kaber@trash.net> | |
59 | + * | |
60 | + * This program is free software; you can redistribute it and/or | |
61 | + * modify it under the terms of the GNU General Public License | |
62 | + * as published by the Free Software Foundation; either version | |
63 | + * 2 of the License, or (at your option) any later version. | |
64 | + */ | |
65 | +/* | |
66 | + * This helper tracks locally originating NetBIOS name service | |
67 | + * requests by issuing permanent expectations (valid until | |
68 | + * timing out) matching all reply connections from the | |
69 | + * destination network. The only NetBIOS specific thing is | |
70 | + * actually the port number. | |
71 | + */ | |
72 | +#include <linux/kernel.h> | |
73 | +#include <linux/module.h> | |
74 | +#include <linux/init.h> | |
75 | +#include <linux/skbuff.h> | |
76 | +#include <linux/netdevice.h> | |
77 | +#include <linux/inetdevice.h> | |
78 | +#include <linux/if_addr.h> | |
79 | +#include <linux/in.h> | |
80 | +#include <linux/ip.h> | |
81 | +#include <linux/netfilter.h> | |
82 | +#include <net/route.h> | |
83 | + | |
84 | +#include <net/netfilter/nf_conntrack.h> | |
85 | +#include <net/netfilter/nf_conntrack_helper.h> | |
86 | +#include <net/netfilter/nf_conntrack_expect.h> | |
87 | + | |
88 | +#define SLP_PORT 427 | |
89 | + | |
90 | +MODULE_AUTHOR("Jiri Bohac <jbohac@suse.cz>"); | |
91 | +MODULE_DESCRIPTION("SLP broadcast connection tracking helper"); | |
92 | +MODULE_LICENSE("GPL"); | |
93 | +MODULE_ALIAS("ip_conntrack_slp"); | |
94 | + | |
95 | +static unsigned int timeout __read_mostly = 3; | |
96 | +module_param(timeout, uint, 0400); | |
97 | +MODULE_PARM_DESC(timeout, "timeout for master connection/replies in seconds"); | |
98 | + | |
99 | +static int help(struct sk_buff *skb, unsigned int protoff, | |
100 | + struct nf_conn *ct, enum ip_conntrack_info ctinfo) | |
101 | +{ | |
102 | + struct nf_conntrack_expect *exp; | |
103 | + struct iphdr *iph = ip_hdr(skb); | |
104 | + struct rtable *rt = skb->rtable; | |
105 | + struct in_device *in_dev; | |
106 | + __be32 mask = 0; | |
107 | + | |
108 | + /* we're only interested in locally generated packets */ | |
109 | + if (skb->sk == NULL) | |
110 | + goto out; | |
111 | + if (rt == NULL || !(rt->rt_flags & RTCF_BROADCAST)) | |
112 | + goto out; | |
113 | + if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) | |
114 | + goto out; | |
115 | + | |
116 | + rcu_read_lock(); | |
117 | + in_dev = __in_dev_get_rcu(rt->u.dst.dev); | |
118 | + if (in_dev != NULL) { | |
119 | + for_primary_ifa(in_dev) { | |
120 | + if (ifa->ifa_broadcast == iph->daddr) { | |
121 | + mask = ifa->ifa_mask; | |
122 | + break; | |
123 | + } | |
124 | + } endfor_ifa(in_dev); | |
125 | + } | |
126 | + rcu_read_unlock(); | |
127 | + | |
128 | + if (mask == 0) | |
129 | + goto out; | |
130 | + | |
131 | + exp = nf_ct_expect_alloc(ct); | |
132 | + if (exp == NULL) | |
133 | + goto out; | |
134 | + | |
135 | + exp->tuple = ct->tuplehash[IP_CT_DIR_REPLY].tuple; | |
136 | + exp->tuple.src.u.udp.port = htons(SLP_PORT); | |
137 | + | |
138 | + exp->mask.src.u3.ip = mask; | |
139 | + exp->mask.src.u.udp.port = htons(0xFFFF); | |
140 | + | |
141 | + exp->expectfn = NULL; | |
142 | + exp->flags = NF_CT_EXPECT_PERMANENT; | |
143 | + exp->class = NF_CT_EXPECT_CLASS_DEFAULT; | |
144 | + exp->helper = NULL; | |
145 | + | |
146 | + nf_ct_expect_related(exp); | |
147 | + nf_ct_expect_put(exp); | |
148 | + | |
149 | + nf_ct_refresh(ct, skb, timeout * HZ); | |
150 | +out: | |
151 | + return NF_ACCEPT; | |
152 | +} | |
153 | + | |
154 | +static struct nf_conntrack_expect_policy exp_policy = { | |
155 | + .max_expected = 1, | |
156 | +}; | |
157 | + | |
158 | +static struct nf_conntrack_helper helper __read_mostly = { | |
159 | + .name = "slp", | |
160 | + .tuple.src.l3num = AF_INET, | |
161 | + .tuple.src.u.udp.port = __constant_htons(SLP_PORT), | |
162 | + .tuple.dst.protonum = IPPROTO_UDP, | |
163 | + .me = THIS_MODULE, | |
164 | + .help = help, | |
165 | + .expect_policy = &exp_policy, | |
166 | +}; | |
167 | + | |
168 | +static int __init nf_conntrack_slp_init(void) | |
169 | +{ | |
170 | + exp_policy.timeout = timeout; | |
171 | + return nf_conntrack_helper_register(&helper); | |
172 | +} | |
173 | + | |
174 | +static void __exit nf_conntrack_slp_fini(void) | |
175 | +{ | |
176 | + nf_conntrack_helper_unregister(&helper); | |
177 | +} | |
178 | + | |
179 | +module_init(nf_conntrack_slp_init); | |
180 | +module_exit(nf_conntrack_slp_fini); |