1 // SPDX-License-Identifier: GPL-2.0-only
2 /* SANE connection tracking helper
3 * (SANE = Scanner Access Now Easy)
4 * For documentation about the SANE network protocol see
5 * http://www.sane-project.org/html/doc015.html
8 /* Copyright (C) 2007 Red Hat, Inc.
9 * Author: Michal Schmidt <mschmidt@redhat.com>
10 * Based on the FTP conntrack helper (net/netfilter/nf_conntrack_ftp.c):
11 * (C) 1999-2001 Paul `Rusty' Russell
12 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
13 * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
14 * (C) 2003 Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
19 #include <linux/module.h>
20 #include <linux/moduleparam.h>
21 #include <linux/netfilter.h>
22 #include <linux/slab.h>
24 #include <linux/tcp.h>
25 #include <net/netfilter/nf_conntrack.h>
26 #include <net/netfilter/nf_conntrack_helper.h>
27 #include <net/netfilter/nf_conntrack_expect.h>
28 #include <linux/netfilter/nf_conntrack_sane.h>
30 #define HELPER_NAME "sane"
32 MODULE_LICENSE("GPL");
33 MODULE_AUTHOR("Michal Schmidt <mschmidt@redhat.com>");
34 MODULE_DESCRIPTION("SANE connection tracking helper");
35 MODULE_ALIAS_NFCT_HELPER(HELPER_NAME
);
37 static char *sane_buffer
;
39 static DEFINE_SPINLOCK(nf_sane_lock
);
42 static u_int16_t ports
[MAX_PORTS
];
43 static unsigned int ports_c
;
44 module_param_array(ports
, ushort
, &ports_c
, 0400);
48 #define SANE_NET_START 7 /* RPC code */
53 struct sane_reply_net_start
{
55 #define SANE_STATUS_SUCCESS 0
59 /* other fields aren't interesting for conntrack */
62 static int help(struct sk_buff
*skb
,
65 enum ip_conntrack_info ctinfo
)
67 unsigned int dataoff
, datalen
;
68 const struct tcphdr
*th
;
72 int dir
= CTINFO2DIR(ctinfo
);
73 struct nf_ct_sane_master
*ct_sane_info
= nfct_help_data(ct
);
74 struct nf_conntrack_expect
*exp
;
75 struct nf_conntrack_tuple
*tuple
;
76 struct sane_request
*req
;
77 struct sane_reply_net_start
*reply
;
79 /* Until there's been traffic both ways, don't look in packets. */
80 if (ctinfo
!= IP_CT_ESTABLISHED
&&
81 ctinfo
!= IP_CT_ESTABLISHED_REPLY
)
84 /* Not a full tcp header? */
85 th
= skb_header_pointer(skb
, protoff
, sizeof(_tcph
), &_tcph
);
90 dataoff
= protoff
+ th
->doff
* 4;
91 if (dataoff
>= skb
->len
)
94 datalen
= skb
->len
- dataoff
;
96 spin_lock_bh(&nf_sane_lock
);
97 sb_ptr
= skb_header_pointer(skb
, dataoff
, datalen
, sane_buffer
);
98 BUG_ON(sb_ptr
== NULL
);
100 if (dir
== IP_CT_DIR_ORIGINAL
) {
101 if (datalen
!= sizeof(struct sane_request
))
105 if (req
->RPC_code
!= htonl(SANE_NET_START
)) {
106 /* Not an interesting command */
107 ct_sane_info
->state
= SANE_STATE_NORMAL
;
111 /* We're interested in the next reply */
112 ct_sane_info
->state
= SANE_STATE_START_REQUESTED
;
116 /* Is it a reply to an uninteresting command? */
117 if (ct_sane_info
->state
!= SANE_STATE_START_REQUESTED
)
120 /* It's a reply to SANE_NET_START. */
121 ct_sane_info
->state
= SANE_STATE_NORMAL
;
123 if (datalen
< sizeof(struct sane_reply_net_start
)) {
124 pr_debug("NET_START reply too short\n");
129 if (reply
->status
!= htonl(SANE_STATUS_SUCCESS
)) {
130 /* saned refused the command */
131 pr_debug("unsuccessful SANE_STATUS = %u\n",
132 ntohl(reply
->status
));
136 /* Invalid saned reply? Ignore it. */
137 if (reply
->zero
!= 0)
140 exp
= nf_ct_expect_alloc(ct
);
142 nf_ct_helper_log(skb
, ct
, "cannot alloc expectation");
147 tuple
= &ct
->tuplehash
[IP_CT_DIR_ORIGINAL
].tuple
;
148 nf_ct_expect_init(exp
, NF_CT_EXPECT_CLASS_DEFAULT
, nf_ct_l3num(ct
),
149 &tuple
->src
.u3
, &tuple
->dst
.u3
,
150 IPPROTO_TCP
, NULL
, &reply
->port
);
152 pr_debug("expect: ");
153 nf_ct_dump_tuple(&exp
->tuple
);
155 /* Can't expect this? Best to drop packet now. */
156 if (nf_ct_expect_related(exp
, 0) != 0) {
157 nf_ct_helper_log(skb
, ct
, "cannot add expectation");
161 nf_ct_expect_put(exp
);
164 spin_unlock_bh(&nf_sane_lock
);
168 static struct nf_conntrack_helper sane
[MAX_PORTS
* 2] __read_mostly
;
170 static const struct nf_conntrack_expect_policy sane_exp_policy
= {
175 static void __exit
nf_conntrack_sane_fini(void)
177 nf_conntrack_helpers_unregister(sane
, ports_c
* 2);
181 static int __init
nf_conntrack_sane_init(void)
185 NF_CT_HELPER_BUILD_BUG_ON(sizeof(struct nf_ct_sane_master
));
187 sane_buffer
= kmalloc(65536, GFP_KERNEL
);
192 ports
[ports_c
++] = SANE_PORT
;
194 /* FIXME should be configurable whether IPv4 and IPv6 connections
195 are tracked or not - YK */
196 for (i
= 0; i
< ports_c
; i
++) {
197 nf_ct_helper_init(&sane
[2 * i
], AF_INET
, IPPROTO_TCP
,
198 HELPER_NAME
, SANE_PORT
, ports
[i
], ports
[i
],
199 &sane_exp_policy
, 0, help
, NULL
,
201 nf_ct_helper_init(&sane
[2 * i
+ 1], AF_INET6
, IPPROTO_TCP
,
202 HELPER_NAME
, SANE_PORT
, ports
[i
], ports
[i
],
203 &sane_exp_policy
, 0, help
, NULL
,
207 ret
= nf_conntrack_helpers_register(sane
, ports_c
* 2);
209 pr_err("failed to register helpers\n");
217 module_init(nf_conntrack_sane_init
);
218 module_exit(nf_conntrack_sane_fini
);