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);