16fecd198SMichal Schmidt /* SANE connection tracking helper 26fecd198SMichal Schmidt * (SANE = Scanner Access Now Easy) 36fecd198SMichal Schmidt * For documentation about the SANE network protocol see 46fecd198SMichal Schmidt * http://www.sane-project.org/html/doc015.html 56fecd198SMichal Schmidt */ 66fecd198SMichal Schmidt 76fecd198SMichal Schmidt /* Copyright (C) 2007 Red Hat, Inc. 86fecd198SMichal Schmidt * Author: Michal Schmidt <mschmidt@redhat.com> 96fecd198SMichal Schmidt * Based on the FTP conntrack helper (net/netfilter/nf_conntrack_ftp.c): 106fecd198SMichal Schmidt * (C) 1999-2001 Paul `Rusty' Russell 116fecd198SMichal Schmidt * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org> 126fecd198SMichal Schmidt * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org> 136fecd198SMichal Schmidt * (C) 2003 Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp> 146fecd198SMichal Schmidt * 156fecd198SMichal Schmidt * This program is free software; you can redistribute it and/or modify 166fecd198SMichal Schmidt * it under the terms of the GNU General Public License version 2 as 176fecd198SMichal Schmidt * published by the Free Software Foundation. 186fecd198SMichal Schmidt */ 196fecd198SMichal Schmidt 206fecd198SMichal Schmidt #include <linux/module.h> 216fecd198SMichal Schmidt #include <linux/moduleparam.h> 226fecd198SMichal Schmidt #include <linux/netfilter.h> 236fecd198SMichal Schmidt #include <linux/in.h> 246fecd198SMichal Schmidt #include <linux/tcp.h> 256fecd198SMichal Schmidt #include <net/netfilter/nf_conntrack.h> 266fecd198SMichal Schmidt #include <net/netfilter/nf_conntrack_helper.h> 276fecd198SMichal Schmidt #include <net/netfilter/nf_conntrack_expect.h> 286fecd198SMichal Schmidt #include <linux/netfilter/nf_conntrack_sane.h> 296fecd198SMichal Schmidt 306fecd198SMichal Schmidt MODULE_LICENSE("GPL"); 316fecd198SMichal Schmidt MODULE_AUTHOR("Michal Schmidt <mschmidt@redhat.com>"); 326fecd198SMichal Schmidt MODULE_DESCRIPTION("SANE connection tracking helper"); 336fecd198SMichal Schmidt 346fecd198SMichal Schmidt static char *sane_buffer; 356fecd198SMichal Schmidt 366fecd198SMichal Schmidt static DEFINE_SPINLOCK(nf_sane_lock); 376fecd198SMichal Schmidt 386fecd198SMichal Schmidt #define MAX_PORTS 8 396fecd198SMichal Schmidt static u_int16_t ports[MAX_PORTS]; 406fecd198SMichal Schmidt static unsigned int ports_c; 416fecd198SMichal Schmidt module_param_array(ports, ushort, &ports_c, 0400); 426fecd198SMichal Schmidt 436fecd198SMichal Schmidt struct sane_request { 446fecd198SMichal Schmidt __be32 RPC_code; 456fecd198SMichal Schmidt #define SANE_NET_START 7 /* RPC code */ 466fecd198SMichal Schmidt 476fecd198SMichal Schmidt __be32 handle; 486fecd198SMichal Schmidt }; 496fecd198SMichal Schmidt 506fecd198SMichal Schmidt struct sane_reply_net_start { 516fecd198SMichal Schmidt __be32 status; 526fecd198SMichal Schmidt #define SANE_STATUS_SUCCESS 0 536fecd198SMichal Schmidt 546fecd198SMichal Schmidt __be16 zero; 556fecd198SMichal Schmidt __be16 port; 566fecd198SMichal Schmidt /* other fields aren't interesting for conntrack */ 576fecd198SMichal Schmidt }; 586fecd198SMichal Schmidt 593db05feaSHerbert Xu static int help(struct sk_buff *skb, 606fecd198SMichal Schmidt unsigned int protoff, 616fecd198SMichal Schmidt struct nf_conn *ct, 626fecd198SMichal Schmidt enum ip_conntrack_info ctinfo) 636fecd198SMichal Schmidt { 646fecd198SMichal Schmidt unsigned int dataoff, datalen; 6502e23f40SJan Engelhardt const struct tcphdr *th; 6602e23f40SJan Engelhardt struct tcphdr _tcph; 6702e23f40SJan Engelhardt void *sb_ptr; 686fecd198SMichal Schmidt int ret = NF_ACCEPT; 696fecd198SMichal Schmidt int dir = CTINFO2DIR(ctinfo); 706fecd198SMichal Schmidt struct nf_ct_sane_master *ct_sane_info; 716fecd198SMichal Schmidt struct nf_conntrack_expect *exp; 726fecd198SMichal Schmidt struct nf_conntrack_tuple *tuple; 736fecd198SMichal Schmidt struct sane_request *req; 746fecd198SMichal Schmidt struct sane_reply_net_start *reply; 756fecd198SMichal Schmidt 766fecd198SMichal Schmidt ct_sane_info = &nfct_help(ct)->help.ct_sane_info; 776fecd198SMichal Schmidt /* Until there's been traffic both ways, don't look in packets. */ 786fecd198SMichal Schmidt if (ctinfo != IP_CT_ESTABLISHED && 796fecd198SMichal Schmidt ctinfo != IP_CT_ESTABLISHED+IP_CT_IS_REPLY) 806fecd198SMichal Schmidt return NF_ACCEPT; 816fecd198SMichal Schmidt 826fecd198SMichal Schmidt /* Not a full tcp header? */ 833db05feaSHerbert Xu th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph); 846fecd198SMichal Schmidt if (th == NULL) 856fecd198SMichal Schmidt return NF_ACCEPT; 866fecd198SMichal Schmidt 876fecd198SMichal Schmidt /* No data? */ 886fecd198SMichal Schmidt dataoff = protoff + th->doff * 4; 893db05feaSHerbert Xu if (dataoff >= skb->len) 906fecd198SMichal Schmidt return NF_ACCEPT; 916fecd198SMichal Schmidt 923db05feaSHerbert Xu datalen = skb->len - dataoff; 936fecd198SMichal Schmidt 946fecd198SMichal Schmidt spin_lock_bh(&nf_sane_lock); 953db05feaSHerbert Xu sb_ptr = skb_header_pointer(skb, dataoff, datalen, sane_buffer); 966fecd198SMichal Schmidt BUG_ON(sb_ptr == NULL); 976fecd198SMichal Schmidt 986fecd198SMichal Schmidt if (dir == IP_CT_DIR_ORIGINAL) { 996fecd198SMichal Schmidt if (datalen != sizeof(struct sane_request)) 1006fecd198SMichal Schmidt goto out; 1016fecd198SMichal Schmidt 10202e23f40SJan Engelhardt req = sb_ptr; 1036fecd198SMichal Schmidt if (req->RPC_code != htonl(SANE_NET_START)) { 1046fecd198SMichal Schmidt /* Not an interesting command */ 1056fecd198SMichal Schmidt ct_sane_info->state = SANE_STATE_NORMAL; 1066fecd198SMichal Schmidt goto out; 1076fecd198SMichal Schmidt } 1086fecd198SMichal Schmidt 1096fecd198SMichal Schmidt /* We're interested in the next reply */ 1106fecd198SMichal Schmidt ct_sane_info->state = SANE_STATE_START_REQUESTED; 1116fecd198SMichal Schmidt goto out; 1126fecd198SMichal Schmidt } 1136fecd198SMichal Schmidt 1146fecd198SMichal Schmidt /* Is it a reply to an uninteresting command? */ 1156fecd198SMichal Schmidt if (ct_sane_info->state != SANE_STATE_START_REQUESTED) 1166fecd198SMichal Schmidt goto out; 1176fecd198SMichal Schmidt 1186fecd198SMichal Schmidt /* It's a reply to SANE_NET_START. */ 1196fecd198SMichal Schmidt ct_sane_info->state = SANE_STATE_NORMAL; 1206fecd198SMichal Schmidt 1216fecd198SMichal Schmidt if (datalen < sizeof(struct sane_reply_net_start)) { 1220d53778eSPatrick McHardy pr_debug("nf_ct_sane: NET_START reply too short\n"); 1236fecd198SMichal Schmidt goto out; 1246fecd198SMichal Schmidt } 1256fecd198SMichal Schmidt 12602e23f40SJan Engelhardt reply = sb_ptr; 1276fecd198SMichal Schmidt if (reply->status != htonl(SANE_STATUS_SUCCESS)) { 1286fecd198SMichal Schmidt /* saned refused the command */ 1290d53778eSPatrick McHardy pr_debug("nf_ct_sane: unsuccessful SANE_STATUS = %u\n", 1306fecd198SMichal Schmidt ntohl(reply->status)); 1316fecd198SMichal Schmidt goto out; 1326fecd198SMichal Schmidt } 1336fecd198SMichal Schmidt 1346fecd198SMichal Schmidt /* Invalid saned reply? Ignore it. */ 1356fecd198SMichal Schmidt if (reply->zero != 0) 1366fecd198SMichal Schmidt goto out; 1376fecd198SMichal Schmidt 1386823645dSPatrick McHardy exp = nf_ct_expect_alloc(ct); 1396fecd198SMichal Schmidt if (exp == NULL) { 1406fecd198SMichal Schmidt ret = NF_DROP; 1416fecd198SMichal Schmidt goto out; 1426fecd198SMichal Schmidt } 1436fecd198SMichal Schmidt 1446fecd198SMichal Schmidt tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple; 1455e8fbe2aSPatrick McHardy nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, nf_ct_l3num(ct), 1466002f266SPatrick McHardy &tuple->src.u3, &tuple->dst.u3, 1476823645dSPatrick McHardy IPPROTO_TCP, NULL, &reply->port); 1486fecd198SMichal Schmidt 1490d53778eSPatrick McHardy pr_debug("nf_ct_sane: expect: "); 1503c9fba65SJan Engelhardt nf_ct_dump_tuple(&exp->tuple); 1516fecd198SMichal Schmidt 1526fecd198SMichal Schmidt /* Can't expect this? Best to drop packet now. */ 1536823645dSPatrick McHardy if (nf_ct_expect_related(exp) != 0) 1546fecd198SMichal Schmidt ret = NF_DROP; 1556fecd198SMichal Schmidt 1566823645dSPatrick McHardy nf_ct_expect_put(exp); 1576fecd198SMichal Schmidt 1586fecd198SMichal Schmidt out: 1596fecd198SMichal Schmidt spin_unlock_bh(&nf_sane_lock); 1606fecd198SMichal Schmidt return ret; 1616fecd198SMichal Schmidt } 1626fecd198SMichal Schmidt 163ec59a111SPatrick McHardy static struct nf_conntrack_helper sane[MAX_PORTS][2] __read_mostly; 164ec59a111SPatrick McHardy static char sane_names[MAX_PORTS][2][sizeof("sane-65535")] __read_mostly; 1656fecd198SMichal Schmidt 1666002f266SPatrick McHardy static const struct nf_conntrack_expect_policy sane_exp_policy = { 1676002f266SPatrick McHardy .max_expected = 1, 1686002f266SPatrick McHardy .timeout = 5 * 60, 1696002f266SPatrick McHardy }; 1706002f266SPatrick McHardy 1716fecd198SMichal Schmidt /* don't make this __exit, since it's called from __init ! */ 1726fecd198SMichal Schmidt static void nf_conntrack_sane_fini(void) 1736fecd198SMichal Schmidt { 1746fecd198SMichal Schmidt int i, j; 1756fecd198SMichal Schmidt 1766fecd198SMichal Schmidt for (i = 0; i < ports_c; i++) { 1776fecd198SMichal Schmidt for (j = 0; j < 2; j++) { 1780d53778eSPatrick McHardy pr_debug("nf_ct_sane: unregistering helper for pf: %d " 1796fecd198SMichal Schmidt "port: %d\n", 1806fecd198SMichal Schmidt sane[i][j].tuple.src.l3num, ports[i]); 1816fecd198SMichal Schmidt nf_conntrack_helper_unregister(&sane[i][j]); 1826fecd198SMichal Schmidt } 1836fecd198SMichal Schmidt } 1846fecd198SMichal Schmidt 1856fecd198SMichal Schmidt kfree(sane_buffer); 1866fecd198SMichal Schmidt } 1876fecd198SMichal Schmidt 1886fecd198SMichal Schmidt static int __init nf_conntrack_sane_init(void) 1896fecd198SMichal Schmidt { 1906fecd198SMichal Schmidt int i, j = -1, ret = 0; 1916fecd198SMichal Schmidt char *tmpname; 1926fecd198SMichal Schmidt 1936fecd198SMichal Schmidt sane_buffer = kmalloc(65536, GFP_KERNEL); 1946fecd198SMichal Schmidt if (!sane_buffer) 1956fecd198SMichal Schmidt return -ENOMEM; 1966fecd198SMichal Schmidt 1976fecd198SMichal Schmidt if (ports_c == 0) 1986fecd198SMichal Schmidt ports[ports_c++] = SANE_PORT; 1996fecd198SMichal Schmidt 2006fecd198SMichal Schmidt /* FIXME should be configurable whether IPv4 and IPv6 connections 2016fecd198SMichal Schmidt are tracked or not - YK */ 2026fecd198SMichal Schmidt for (i = 0; i < ports_c; i++) { 2036fecd198SMichal Schmidt sane[i][0].tuple.src.l3num = PF_INET; 2046fecd198SMichal Schmidt sane[i][1].tuple.src.l3num = PF_INET6; 2056fecd198SMichal Schmidt for (j = 0; j < 2; j++) { 2066fecd198SMichal Schmidt sane[i][j].tuple.src.u.tcp.port = htons(ports[i]); 2076fecd198SMichal Schmidt sane[i][j].tuple.dst.protonum = IPPROTO_TCP; 2086002f266SPatrick McHardy sane[i][j].expect_policy = &sane_exp_policy; 2096fecd198SMichal Schmidt sane[i][j].me = THIS_MODULE; 2106fecd198SMichal Schmidt sane[i][j].help = help; 2116fecd198SMichal Schmidt tmpname = &sane_names[i][j][0]; 2126fecd198SMichal Schmidt if (ports[i] == SANE_PORT) 2136fecd198SMichal Schmidt sprintf(tmpname, "sane"); 2146fecd198SMichal Schmidt else 2156fecd198SMichal Schmidt sprintf(tmpname, "sane-%d", ports[i]); 2166fecd198SMichal Schmidt sane[i][j].name = tmpname; 2176fecd198SMichal Schmidt 2180d53778eSPatrick McHardy pr_debug("nf_ct_sane: registering helper for pf: %d " 2196fecd198SMichal Schmidt "port: %d\n", 2206fecd198SMichal Schmidt sane[i][j].tuple.src.l3num, ports[i]); 2216fecd198SMichal Schmidt ret = nf_conntrack_helper_register(&sane[i][j]); 2226fecd198SMichal Schmidt if (ret) { 2236fecd198SMichal Schmidt printk(KERN_ERR "nf_ct_sane: failed to " 2246fecd198SMichal Schmidt "register helper for pf: %d port: %d\n", 2256fecd198SMichal Schmidt sane[i][j].tuple.src.l3num, ports[i]); 2266fecd198SMichal Schmidt nf_conntrack_sane_fini(); 2276fecd198SMichal Schmidt return ret; 2286fecd198SMichal Schmidt } 2296fecd198SMichal Schmidt } 2306fecd198SMichal Schmidt } 2316fecd198SMichal Schmidt 2326fecd198SMichal Schmidt return 0; 2336fecd198SMichal Schmidt } 2346fecd198SMichal Schmidt 2356fecd198SMichal Schmidt module_init(nf_conntrack_sane_init); 2366fecd198SMichal Schmidt module_exit(nf_conntrack_sane_fini); 237