Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 1 | /* SANE connection tracking helper |
| 2 | * (SANE = Scanner Access Now Easy) |
| 3 | * For documentation about the SANE network protocol see |
| 4 | * http://www.sane-project.org/html/doc015.html |
| 5 | */ |
| 6 | |
| 7 | /* Copyright (C) 2007 Red Hat, Inc. |
| 8 | * Author: Michal Schmidt <mschmidt@redhat.com> |
| 9 | * Based on the FTP conntrack helper (net/netfilter/nf_conntrack_ftp.c): |
| 10 | * (C) 1999-2001 Paul `Rusty' Russell |
| 11 | * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org> |
| 12 | * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org> |
| 13 | * (C) 2003 Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp> |
| 14 | * |
| 15 | * This program is free software; you can redistribute it and/or modify |
| 16 | * it under the terms of the GNU General Public License version 2 as |
| 17 | * published by the Free Software Foundation. |
| 18 | */ |
| 19 | |
Pablo Neira Ayuso | ad6d950 | 2016-01-03 22:41:24 +0100 | [diff] [blame] | 20 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| 21 | |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 22 | #include <linux/module.h> |
| 23 | #include <linux/moduleparam.h> |
| 24 | #include <linux/netfilter.h> |
Tejun Heo | 5a0e3ad | 2010-03-24 17:04:11 +0900 | [diff] [blame] | 25 | #include <linux/slab.h> |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 26 | #include <linux/in.h> |
| 27 | #include <linux/tcp.h> |
| 28 | #include <net/netfilter/nf_conntrack.h> |
| 29 | #include <net/netfilter/nf_conntrack_helper.h> |
| 30 | #include <net/netfilter/nf_conntrack_expect.h> |
| 31 | #include <linux/netfilter/nf_conntrack_sane.h> |
| 32 | |
| 33 | MODULE_LICENSE("GPL"); |
| 34 | MODULE_AUTHOR("Michal Schmidt <mschmidt@redhat.com>"); |
| 35 | MODULE_DESCRIPTION("SANE connection tracking helper"); |
Pablo Neira Ayuso | 4dc06f9 | 2008-11-17 16:01:42 +0100 | [diff] [blame] | 36 | MODULE_ALIAS_NFCT_HELPER("sane"); |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 37 | |
| 38 | static char *sane_buffer; |
| 39 | |
| 40 | static DEFINE_SPINLOCK(nf_sane_lock); |
| 41 | |
| 42 | #define MAX_PORTS 8 |
| 43 | static u_int16_t ports[MAX_PORTS]; |
| 44 | static unsigned int ports_c; |
| 45 | module_param_array(ports, ushort, &ports_c, 0400); |
| 46 | |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 47 | struct sane_request { |
| 48 | __be32 RPC_code; |
| 49 | #define SANE_NET_START 7 /* RPC code */ |
| 50 | |
| 51 | __be32 handle; |
| 52 | }; |
| 53 | |
| 54 | struct sane_reply_net_start { |
| 55 | __be32 status; |
| 56 | #define SANE_STATUS_SUCCESS 0 |
| 57 | |
| 58 | __be16 zero; |
| 59 | __be16 port; |
| 60 | /* other fields aren't interesting for conntrack */ |
| 61 | }; |
| 62 | |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 63 | static int help(struct sk_buff *skb, |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 64 | unsigned int protoff, |
| 65 | struct nf_conn *ct, |
| 66 | enum ip_conntrack_info ctinfo) |
| 67 | { |
| 68 | unsigned int dataoff, datalen; |
Jan Engelhardt | 02e23f4 | 2008-01-31 04:51:45 -0800 | [diff] [blame] | 69 | const struct tcphdr *th; |
| 70 | struct tcphdr _tcph; |
| 71 | void *sb_ptr; |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 72 | int ret = NF_ACCEPT; |
| 73 | int dir = CTINFO2DIR(ctinfo); |
Pablo Neira Ayuso | 1afc567 | 2012-06-07 12:11:50 +0200 | [diff] [blame] | 74 | struct nf_ct_sane_master *ct_sane_info = nfct_help_data(ct); |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 75 | struct nf_conntrack_expect *exp; |
| 76 | struct nf_conntrack_tuple *tuple; |
| 77 | struct sane_request *req; |
| 78 | struct sane_reply_net_start *reply; |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 79 | |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 80 | /* Until there's been traffic both ways, don't look in packets. */ |
| 81 | if (ctinfo != IP_CT_ESTABLISHED && |
Eric Dumazet | fb04883 | 2011-05-19 15:44:27 +0200 | [diff] [blame] | 82 | ctinfo != IP_CT_ESTABLISHED_REPLY) |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 83 | return NF_ACCEPT; |
| 84 | |
| 85 | /* Not a full tcp header? */ |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 86 | th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph); |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 87 | if (th == NULL) |
| 88 | return NF_ACCEPT; |
| 89 | |
| 90 | /* No data? */ |
| 91 | dataoff = protoff + th->doff * 4; |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 92 | if (dataoff >= skb->len) |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 93 | return NF_ACCEPT; |
| 94 | |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 95 | datalen = skb->len - dataoff; |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 96 | |
| 97 | spin_lock_bh(&nf_sane_lock); |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 98 | sb_ptr = skb_header_pointer(skb, dataoff, datalen, sane_buffer); |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 99 | BUG_ON(sb_ptr == NULL); |
| 100 | |
| 101 | if (dir == IP_CT_DIR_ORIGINAL) { |
| 102 | if (datalen != sizeof(struct sane_request)) |
| 103 | goto out; |
| 104 | |
Jan Engelhardt | 02e23f4 | 2008-01-31 04:51:45 -0800 | [diff] [blame] | 105 | req = sb_ptr; |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 106 | if (req->RPC_code != htonl(SANE_NET_START)) { |
| 107 | /* Not an interesting command */ |
| 108 | ct_sane_info->state = SANE_STATE_NORMAL; |
| 109 | goto out; |
| 110 | } |
| 111 | |
| 112 | /* We're interested in the next reply */ |
| 113 | ct_sane_info->state = SANE_STATE_START_REQUESTED; |
| 114 | goto out; |
| 115 | } |
| 116 | |
| 117 | /* Is it a reply to an uninteresting command? */ |
| 118 | if (ct_sane_info->state != SANE_STATE_START_REQUESTED) |
| 119 | goto out; |
| 120 | |
| 121 | /* It's a reply to SANE_NET_START. */ |
| 122 | ct_sane_info->state = SANE_STATE_NORMAL; |
| 123 | |
| 124 | if (datalen < sizeof(struct sane_reply_net_start)) { |
Pablo Neira Ayuso | ad6d950 | 2016-01-03 22:41:24 +0100 | [diff] [blame] | 125 | pr_debug("NET_START reply too short\n"); |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 126 | goto out; |
| 127 | } |
| 128 | |
Jan Engelhardt | 02e23f4 | 2008-01-31 04:51:45 -0800 | [diff] [blame] | 129 | reply = sb_ptr; |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 130 | if (reply->status != htonl(SANE_STATUS_SUCCESS)) { |
| 131 | /* saned refused the command */ |
Pablo Neira Ayuso | ad6d950 | 2016-01-03 22:41:24 +0100 | [diff] [blame] | 132 | pr_debug("unsuccessful SANE_STATUS = %u\n", |
Patrick McHardy | 0d53778 | 2007-07-07 22:39:38 -0700 | [diff] [blame] | 133 | ntohl(reply->status)); |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 134 | goto out; |
| 135 | } |
| 136 | |
| 137 | /* Invalid saned reply? Ignore it. */ |
| 138 | if (reply->zero != 0) |
| 139 | goto out; |
| 140 | |
Patrick McHardy | 6823645 | 2007-07-07 22:30:49 -0700 | [diff] [blame] | 141 | exp = nf_ct_expect_alloc(ct); |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 142 | if (exp == NULL) { |
Pablo Neira Ayuso | b20ab9cc | 2013-02-10 18:56:56 +0100 | [diff] [blame] | 143 | nf_ct_helper_log(skb, ct, "cannot alloc expectation"); |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 144 | ret = NF_DROP; |
| 145 | goto out; |
| 146 | } |
| 147 | |
| 148 | tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple; |
Patrick McHardy | 5e8fbe2 | 2008-04-14 11:15:52 +0200 | [diff] [blame] | 149 | nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, nf_ct_l3num(ct), |
Patrick McHardy | 6002f266 | 2008-03-25 20:09:15 -0700 | [diff] [blame] | 150 | &tuple->src.u3, &tuple->dst.u3, |
Patrick McHardy | 6823645 | 2007-07-07 22:30:49 -0700 | [diff] [blame] | 151 | IPPROTO_TCP, NULL, &reply->port); |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 152 | |
Pablo Neira Ayuso | ad6d950 | 2016-01-03 22:41:24 +0100 | [diff] [blame] | 153 | pr_debug("expect: "); |
Jan Engelhardt | 3c9fba6 | 2008-04-14 11:15:54 +0200 | [diff] [blame] | 154 | nf_ct_dump_tuple(&exp->tuple); |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 155 | |
| 156 | /* Can't expect this? Best to drop packet now. */ |
Pablo Neira Ayuso | b20ab9cc | 2013-02-10 18:56:56 +0100 | [diff] [blame] | 157 | if (nf_ct_expect_related(exp) != 0) { |
| 158 | nf_ct_helper_log(skb, ct, "cannot add expectation"); |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 159 | ret = NF_DROP; |
Pablo Neira Ayuso | b20ab9cc | 2013-02-10 18:56:56 +0100 | [diff] [blame] | 160 | } |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 161 | |
Patrick McHardy | 6823645 | 2007-07-07 22:30:49 -0700 | [diff] [blame] | 162 | nf_ct_expect_put(exp); |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 163 | |
| 164 | out: |
| 165 | spin_unlock_bh(&nf_sane_lock); |
| 166 | return ret; |
| 167 | } |
| 168 | |
Gao Feng | 82de0be | 2016-07-18 11:39:23 +0800 | [diff] [blame] | 169 | static struct nf_conntrack_helper sane[MAX_PORTS * 2] __read_mostly; |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 170 | |
Patrick McHardy | 6002f266 | 2008-03-25 20:09:15 -0700 | [diff] [blame] | 171 | static const struct nf_conntrack_expect_policy sane_exp_policy = { |
| 172 | .max_expected = 1, |
| 173 | .timeout = 5 * 60, |
| 174 | }; |
| 175 | |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 176 | /* don't make this __exit, since it's called from __init ! */ |
| 177 | static void nf_conntrack_sane_fini(void) |
| 178 | { |
Gao Feng | 82de0be | 2016-07-18 11:39:23 +0800 | [diff] [blame] | 179 | nf_conntrack_helpers_unregister(sane, ports_c * 2); |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 180 | kfree(sane_buffer); |
| 181 | } |
| 182 | |
| 183 | static int __init nf_conntrack_sane_init(void) |
| 184 | { |
Gao Feng | 82de0be | 2016-07-18 11:39:23 +0800 | [diff] [blame] | 185 | int i, ret = 0; |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 186 | |
| 187 | sane_buffer = kmalloc(65536, GFP_KERNEL); |
| 188 | if (!sane_buffer) |
| 189 | return -ENOMEM; |
| 190 | |
| 191 | if (ports_c == 0) |
| 192 | ports[ports_c++] = SANE_PORT; |
| 193 | |
| 194 | /* FIXME should be configurable whether IPv4 and IPv6 connections |
| 195 | are tracked or not - YK */ |
| 196 | for (i = 0; i < ports_c; i++) { |
Gao Feng | 82de0be | 2016-07-18 11:39:23 +0800 | [diff] [blame] | 197 | nf_ct_helper_init(&sane[2 * i], AF_INET, IPPROTO_TCP, "sane", |
| 198 | SANE_PORT, ports[i], ports[i], |
| 199 | &sane_exp_policy, 0, |
| 200 | sizeof(struct nf_ct_sane_master), help, NULL, |
| 201 | THIS_MODULE); |
| 202 | nf_ct_helper_init(&sane[2 * i + 1], AF_INET6, IPPROTO_TCP, "sane", |
| 203 | SANE_PORT, ports[i], ports[i], |
| 204 | &sane_exp_policy, 0, |
| 205 | sizeof(struct nf_ct_sane_master), help, NULL, |
| 206 | THIS_MODULE); |
| 207 | } |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 208 | |
Gao Feng | 82de0be | 2016-07-18 11:39:23 +0800 | [diff] [blame] | 209 | ret = nf_conntrack_helpers_register(sane, ports_c * 2); |
| 210 | if (ret < 0) { |
| 211 | pr_err("failed to register helpers\n"); |
| 212 | kfree(sane_buffer); |
| 213 | return ret; |
Michal Schmidt | 6fecd19 | 2007-02-07 15:05:12 -0800 | [diff] [blame] | 214 | } |
| 215 | |
| 216 | return 0; |
| 217 | } |
| 218 | |
| 219 | module_init(nf_conntrack_sane_init); |
| 220 | module_exit(nf_conntrack_sane_fini); |