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 #if 0 446fecd198SMichal Schmidt #define DEBUGP printk 456fecd198SMichal Schmidt #else 466fecd198SMichal Schmidt #define DEBUGP(format, args...) 476fecd198SMichal Schmidt #endif 486fecd198SMichal Schmidt 496fecd198SMichal Schmidt struct sane_request { 506fecd198SMichal Schmidt __be32 RPC_code; 516fecd198SMichal Schmidt #define SANE_NET_START 7 /* RPC code */ 526fecd198SMichal Schmidt 536fecd198SMichal Schmidt __be32 handle; 546fecd198SMichal Schmidt }; 556fecd198SMichal Schmidt 566fecd198SMichal Schmidt struct sane_reply_net_start { 576fecd198SMichal Schmidt __be32 status; 586fecd198SMichal Schmidt #define SANE_STATUS_SUCCESS 0 596fecd198SMichal Schmidt 606fecd198SMichal Schmidt __be16 zero; 616fecd198SMichal Schmidt __be16 port; 626fecd198SMichal Schmidt /* other fields aren't interesting for conntrack */ 636fecd198SMichal Schmidt }; 646fecd198SMichal Schmidt 656fecd198SMichal Schmidt static int help(struct sk_buff **pskb, 666fecd198SMichal Schmidt unsigned int protoff, 676fecd198SMichal Schmidt struct nf_conn *ct, 686fecd198SMichal Schmidt enum ip_conntrack_info ctinfo) 696fecd198SMichal Schmidt { 706fecd198SMichal Schmidt unsigned int dataoff, datalen; 716fecd198SMichal Schmidt struct tcphdr _tcph, *th; 726fecd198SMichal Schmidt char *sb_ptr; 736fecd198SMichal Schmidt int ret = NF_ACCEPT; 746fecd198SMichal Schmidt int dir = CTINFO2DIR(ctinfo); 756fecd198SMichal Schmidt struct nf_ct_sane_master *ct_sane_info; 766fecd198SMichal Schmidt struct nf_conntrack_expect *exp; 776fecd198SMichal Schmidt struct nf_conntrack_tuple *tuple; 786fecd198SMichal Schmidt struct sane_request *req; 796fecd198SMichal Schmidt struct sane_reply_net_start *reply; 806fecd198SMichal Schmidt int family = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num; 816fecd198SMichal Schmidt 826fecd198SMichal Schmidt ct_sane_info = &nfct_help(ct)->help.ct_sane_info; 836fecd198SMichal Schmidt /* Until there's been traffic both ways, don't look in packets. */ 846fecd198SMichal Schmidt if (ctinfo != IP_CT_ESTABLISHED && 856fecd198SMichal Schmidt ctinfo != IP_CT_ESTABLISHED+IP_CT_IS_REPLY) 866fecd198SMichal Schmidt return NF_ACCEPT; 876fecd198SMichal Schmidt 886fecd198SMichal Schmidt /* Not a full tcp header? */ 896fecd198SMichal Schmidt th = skb_header_pointer(*pskb, protoff, sizeof(_tcph), &_tcph); 906fecd198SMichal Schmidt if (th == NULL) 916fecd198SMichal Schmidt return NF_ACCEPT; 926fecd198SMichal Schmidt 936fecd198SMichal Schmidt /* No data? */ 946fecd198SMichal Schmidt dataoff = protoff + th->doff * 4; 956fecd198SMichal Schmidt if (dataoff >= (*pskb)->len) 966fecd198SMichal Schmidt return NF_ACCEPT; 976fecd198SMichal Schmidt 986fecd198SMichal Schmidt datalen = (*pskb)->len - dataoff; 996fecd198SMichal Schmidt 1006fecd198SMichal Schmidt spin_lock_bh(&nf_sane_lock); 1016fecd198SMichal Schmidt sb_ptr = skb_header_pointer(*pskb, dataoff, datalen, sane_buffer); 1026fecd198SMichal Schmidt BUG_ON(sb_ptr == NULL); 1036fecd198SMichal Schmidt 1046fecd198SMichal Schmidt if (dir == IP_CT_DIR_ORIGINAL) { 1056fecd198SMichal Schmidt if (datalen != sizeof(struct sane_request)) 1066fecd198SMichal Schmidt goto out; 1076fecd198SMichal Schmidt 1086fecd198SMichal Schmidt req = (struct sane_request *)sb_ptr; 1096fecd198SMichal Schmidt if (req->RPC_code != htonl(SANE_NET_START)) { 1106fecd198SMichal Schmidt /* Not an interesting command */ 1116fecd198SMichal Schmidt ct_sane_info->state = SANE_STATE_NORMAL; 1126fecd198SMichal Schmidt goto out; 1136fecd198SMichal Schmidt } 1146fecd198SMichal Schmidt 1156fecd198SMichal Schmidt /* We're interested in the next reply */ 1166fecd198SMichal Schmidt ct_sane_info->state = SANE_STATE_START_REQUESTED; 1176fecd198SMichal Schmidt goto out; 1186fecd198SMichal Schmidt } 1196fecd198SMichal Schmidt 1206fecd198SMichal Schmidt /* Is it a reply to an uninteresting command? */ 1216fecd198SMichal Schmidt if (ct_sane_info->state != SANE_STATE_START_REQUESTED) 1226fecd198SMichal Schmidt goto out; 1236fecd198SMichal Schmidt 1246fecd198SMichal Schmidt /* It's a reply to SANE_NET_START. */ 1256fecd198SMichal Schmidt ct_sane_info->state = SANE_STATE_NORMAL; 1266fecd198SMichal Schmidt 1276fecd198SMichal Schmidt if (datalen < sizeof(struct sane_reply_net_start)) { 1286fecd198SMichal Schmidt DEBUGP("nf_ct_sane: NET_START reply too short\n"); 1296fecd198SMichal Schmidt goto out; 1306fecd198SMichal Schmidt } 1316fecd198SMichal Schmidt 1326fecd198SMichal Schmidt reply = (struct sane_reply_net_start *)sb_ptr; 1336fecd198SMichal Schmidt if (reply->status != htonl(SANE_STATUS_SUCCESS)) { 1346fecd198SMichal Schmidt /* saned refused the command */ 1356fecd198SMichal Schmidt DEBUGP("nf_ct_sane: unsuccessful SANE_STATUS = %u\n", 1366fecd198SMichal Schmidt ntohl(reply->status)); 1376fecd198SMichal Schmidt goto out; 1386fecd198SMichal Schmidt } 1396fecd198SMichal Schmidt 1406fecd198SMichal Schmidt /* Invalid saned reply? Ignore it. */ 1416fecd198SMichal Schmidt if (reply->zero != 0) 1426fecd198SMichal Schmidt goto out; 1436fecd198SMichal Schmidt 1446823645dSPatrick McHardy exp = nf_ct_expect_alloc(ct); 1456fecd198SMichal Schmidt if (exp == NULL) { 1466fecd198SMichal Schmidt ret = NF_DROP; 1476fecd198SMichal Schmidt goto out; 1486fecd198SMichal Schmidt } 1496fecd198SMichal Schmidt 1506fecd198SMichal Schmidt tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple; 1516823645dSPatrick McHardy nf_ct_expect_init(exp, family, &tuple->src.u3, &tuple->dst.u3, 1526823645dSPatrick McHardy IPPROTO_TCP, NULL, &reply->port); 1536fecd198SMichal Schmidt 1546fecd198SMichal Schmidt DEBUGP("nf_ct_sane: expect: "); 1556fecd198SMichal Schmidt NF_CT_DUMP_TUPLE(&exp->tuple); 1566fecd198SMichal Schmidt NF_CT_DUMP_TUPLE(&exp->mask); 1576fecd198SMichal Schmidt 1586fecd198SMichal Schmidt /* Can't expect this? Best to drop packet now. */ 1596823645dSPatrick McHardy if (nf_ct_expect_related(exp) != 0) 1606fecd198SMichal Schmidt ret = NF_DROP; 1616fecd198SMichal Schmidt 1626823645dSPatrick McHardy nf_ct_expect_put(exp); 1636fecd198SMichal Schmidt 1646fecd198SMichal Schmidt out: 1656fecd198SMichal Schmidt spin_unlock_bh(&nf_sane_lock); 1666fecd198SMichal Schmidt return ret; 1676fecd198SMichal Schmidt } 1686fecd198SMichal Schmidt 1696fecd198SMichal Schmidt static struct nf_conntrack_helper sane[MAX_PORTS][2]; 1706fecd198SMichal Schmidt static char sane_names[MAX_PORTS][2][sizeof("sane-65535")]; 1716fecd198SMichal Schmidt 1726fecd198SMichal Schmidt /* don't make this __exit, since it's called from __init ! */ 1736fecd198SMichal Schmidt static void nf_conntrack_sane_fini(void) 1746fecd198SMichal Schmidt { 1756fecd198SMichal Schmidt int i, j; 1766fecd198SMichal Schmidt 1776fecd198SMichal Schmidt for (i = 0; i < ports_c; i++) { 1786fecd198SMichal Schmidt for (j = 0; j < 2; j++) { 1796fecd198SMichal Schmidt DEBUGP("nf_ct_sane: unregistering helper for pf: %d " 1806fecd198SMichal Schmidt "port: %d\n", 1816fecd198SMichal Schmidt sane[i][j].tuple.src.l3num, ports[i]); 1826fecd198SMichal Schmidt nf_conntrack_helper_unregister(&sane[i][j]); 1836fecd198SMichal Schmidt } 1846fecd198SMichal Schmidt } 1856fecd198SMichal Schmidt 1866fecd198SMichal Schmidt kfree(sane_buffer); 1876fecd198SMichal Schmidt } 1886fecd198SMichal Schmidt 1896fecd198SMichal Schmidt static int __init nf_conntrack_sane_init(void) 1906fecd198SMichal Schmidt { 1916fecd198SMichal Schmidt int i, j = -1, ret = 0; 1926fecd198SMichal Schmidt char *tmpname; 1936fecd198SMichal Schmidt 1946fecd198SMichal Schmidt sane_buffer = kmalloc(65536, GFP_KERNEL); 1956fecd198SMichal Schmidt if (!sane_buffer) 1966fecd198SMichal Schmidt return -ENOMEM; 1976fecd198SMichal Schmidt 1986fecd198SMichal Schmidt if (ports_c == 0) 1996fecd198SMichal Schmidt ports[ports_c++] = SANE_PORT; 2006fecd198SMichal Schmidt 2016fecd198SMichal Schmidt /* FIXME should be configurable whether IPv4 and IPv6 connections 2026fecd198SMichal Schmidt are tracked or not - YK */ 2036fecd198SMichal Schmidt for (i = 0; i < ports_c; i++) { 2046fecd198SMichal Schmidt sane[i][0].tuple.src.l3num = PF_INET; 2056fecd198SMichal Schmidt sane[i][1].tuple.src.l3num = PF_INET6; 2066fecd198SMichal Schmidt for (j = 0; j < 2; j++) { 2076fecd198SMichal Schmidt sane[i][j].tuple.src.u.tcp.port = htons(ports[i]); 2086fecd198SMichal Schmidt sane[i][j].tuple.dst.protonum = IPPROTO_TCP; 2096fecd198SMichal Schmidt sane[i][j].mask.src.u.tcp.port = 0xFFFF; 2106fecd198SMichal Schmidt sane[i][j].mask.dst.protonum = 0xFF; 2116fecd198SMichal Schmidt sane[i][j].max_expected = 1; 2126fecd198SMichal Schmidt sane[i][j].timeout = 5 * 60; /* 5 Minutes */ 2136fecd198SMichal Schmidt sane[i][j].me = THIS_MODULE; 2146fecd198SMichal Schmidt sane[i][j].help = help; 2156fecd198SMichal Schmidt tmpname = &sane_names[i][j][0]; 2166fecd198SMichal Schmidt if (ports[i] == SANE_PORT) 2176fecd198SMichal Schmidt sprintf(tmpname, "sane"); 2186fecd198SMichal Schmidt else 2196fecd198SMichal Schmidt sprintf(tmpname, "sane-%d", ports[i]); 2206fecd198SMichal Schmidt sane[i][j].name = tmpname; 2216fecd198SMichal Schmidt 2226fecd198SMichal Schmidt DEBUGP("nf_ct_sane: registering helper for pf: %d " 2236fecd198SMichal Schmidt "port: %d\n", 2246fecd198SMichal Schmidt sane[i][j].tuple.src.l3num, ports[i]); 2256fecd198SMichal Schmidt ret = nf_conntrack_helper_register(&sane[i][j]); 2266fecd198SMichal Schmidt if (ret) { 2276fecd198SMichal Schmidt printk(KERN_ERR "nf_ct_sane: failed to " 2286fecd198SMichal Schmidt "register helper for pf: %d port: %d\n", 2296fecd198SMichal Schmidt sane[i][j].tuple.src.l3num, ports[i]); 2306fecd198SMichal Schmidt nf_conntrack_sane_fini(); 2316fecd198SMichal Schmidt return ret; 2326fecd198SMichal Schmidt } 2336fecd198SMichal Schmidt } 2346fecd198SMichal Schmidt } 2356fecd198SMichal Schmidt 2366fecd198SMichal Schmidt return 0; 2376fecd198SMichal Schmidt } 2386fecd198SMichal Schmidt 2396fecd198SMichal Schmidt module_init(nf_conntrack_sane_init); 2406fecd198SMichal Schmidt module_exit(nf_conntrack_sane_fini); 241