1/* Amanda extension for IP connection tracking 2 * 3 * (C) 2002 by Brian J. Murrell <netfilter@interlinx.bc.ca> 4 * based on HW's ip_conntrack_irc.c as well as other modules 5 * (C) 2006 Patrick McHardy <kaber@trash.net> 6 * 7 * This program is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License 9 * as published by the Free Software Foundation; either version 10 * 2 of the License, or (at your option) any later version. 11 */ 12#include <linux/kernel.h> 13#include <linux/module.h> 14#include <linux/moduleparam.h> 15#include <linux/textsearch.h> 16#include <linux/skbuff.h> 17#include <linux/in.h> 18#include <linux/udp.h> 19#include <linux/netfilter.h> 20#include <linux/gfp.h> 21 22#include <net/netfilter/nf_conntrack.h> 23#include <net/netfilter/nf_conntrack_expect.h> 24#include <net/netfilter/nf_conntrack_ecache.h> 25#include <net/netfilter/nf_conntrack_helper.h> 26#include <linux/netfilter/nf_conntrack_amanda.h> 27 28static unsigned int master_timeout __read_mostly = 300; 29static char *ts_algo = "kmp"; 30 31MODULE_AUTHOR("Brian J. Murrell <netfilter@interlinx.bc.ca>"); 32MODULE_DESCRIPTION("Amanda connection tracking module"); 33MODULE_LICENSE("GPL"); 34MODULE_ALIAS("ip_conntrack_amanda"); 35MODULE_ALIAS_NFCT_HELPER("amanda"); 36 37module_param(master_timeout, uint, 0600); 38MODULE_PARM_DESC(master_timeout, "timeout for the master connection"); 39module_param(ts_algo, charp, 0400); 40MODULE_PARM_DESC(ts_algo, "textsearch algorithm to use (default kmp)"); 41 42unsigned int (*nf_nat_amanda_hook)(struct sk_buff *skb, 43 enum ip_conntrack_info ctinfo, 44 unsigned int protoff, 45 unsigned int matchoff, 46 unsigned int matchlen, 47 struct nf_conntrack_expect *exp) 48 __read_mostly; 49EXPORT_SYMBOL_GPL(nf_nat_amanda_hook); 50 51enum amanda_strings { 52 SEARCH_CONNECT, 53 SEARCH_NEWLINE, 54 SEARCH_DATA, 55 SEARCH_MESG, 56 SEARCH_INDEX, 57}; 58 59static struct { 60 const char *string; 61 size_t len; 62 struct ts_config *ts; 63} search[] __read_mostly = { 64 [SEARCH_CONNECT] = { 65 .string = "CONNECT ", 66 .len = 8, 67 }, 68 [SEARCH_NEWLINE] = { 69 .string = "\n", 70 .len = 1, 71 }, 72 [SEARCH_DATA] = { 73 .string = "DATA ", 74 .len = 5, 75 }, 76 [SEARCH_MESG] = { 77 .string = "MESG ", 78 .len = 5, 79 }, 80 [SEARCH_INDEX] = { 81 .string = "INDEX ", 82 .len = 6, 83 }, 84}; 85 86static int amanda_help(struct sk_buff *skb, 87 unsigned int protoff, 88 struct nf_conn *ct, 89 enum ip_conntrack_info ctinfo) 90{ 91 struct ts_state ts; 92 struct nf_conntrack_expect *exp; 93 struct nf_conntrack_tuple *tuple; 94 unsigned int dataoff, start, stop, off, i; 95 char pbuf[sizeof("65535")], *tmp; 96 u_int16_t len; 97 __be16 port; 98 int ret = NF_ACCEPT; 99 typeof(nf_nat_amanda_hook) nf_nat_amanda; 100 101 /* Only look at packets from the Amanda server */ 102 if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) 103 return NF_ACCEPT; 104 105 /* increase the UDP timeout of the master connection as replies from 106 * Amanda clients to the server can be quite delayed */ 107 nf_ct_refresh(ct, skb, master_timeout * HZ); 108 109 /* No data? */ 110 dataoff = protoff + sizeof(struct udphdr); 111 if (dataoff >= skb->len) { 112 net_err_ratelimited("amanda_help: skblen = %u\n", skb->len); 113 return NF_ACCEPT; 114 } 115 116 memset(&ts, 0, sizeof(ts)); 117 start = skb_find_text(skb, dataoff, skb->len, 118 search[SEARCH_CONNECT].ts, &ts); 119 if (start == UINT_MAX) 120 goto out; 121 start += dataoff + search[SEARCH_CONNECT].len; 122 123 memset(&ts, 0, sizeof(ts)); 124 stop = skb_find_text(skb, start, skb->len, 125 search[SEARCH_NEWLINE].ts, &ts); 126 if (stop == UINT_MAX) 127 goto out; 128 stop += start; 129 130 for (i = SEARCH_DATA; i <= SEARCH_INDEX; i++) { 131 memset(&ts, 0, sizeof(ts)); 132 off = skb_find_text(skb, start, stop, search[i].ts, &ts); 133 if (off == UINT_MAX) 134 continue; 135 off += start + search[i].len; 136 137 len = min_t(unsigned int, sizeof(pbuf) - 1, stop - off); 138 if (skb_copy_bits(skb, off, pbuf, len)) 139 break; 140 pbuf[len] = '\0'; 141 142 port = htons(simple_strtoul(pbuf, &tmp, 10)); 143 len = tmp - pbuf; 144 if (port == 0 || len > 5) 145 break; 146 147 exp = nf_ct_expect_alloc(ct); 148 if (exp == NULL) { 149 nf_ct_helper_log(skb, ct, "cannot alloc expectation"); 150 ret = NF_DROP; 151 goto out; 152 } 153 tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple; 154 nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, 155 nf_ct_l3num(ct), 156 &tuple->src.u3, &tuple->dst.u3, 157 IPPROTO_TCP, NULL, &port); 158 159 nf_nat_amanda = rcu_dereference(nf_nat_amanda_hook); 160 if (nf_nat_amanda && ct->status & IPS_NAT_MASK) 161 ret = nf_nat_amanda(skb, ctinfo, protoff, 162 off - dataoff, len, exp); 163 else if (nf_ct_expect_related(exp) != 0) { 164 nf_ct_helper_log(skb, ct, "cannot add expectation"); 165 ret = NF_DROP; 166 } 167 nf_ct_expect_put(exp); 168 } 169 170out: 171 return ret; 172} 173 174static const struct nf_conntrack_expect_policy amanda_exp_policy = { 175 .max_expected = 3, 176 .timeout = 180, 177}; 178 179static struct nf_conntrack_helper amanda_helper[2] __read_mostly = { 180 { 181 .name = "amanda", 182 .me = THIS_MODULE, 183 .help = amanda_help, 184 .tuple.src.l3num = AF_INET, 185 .tuple.src.u.udp.port = cpu_to_be16(10080), 186 .tuple.dst.protonum = IPPROTO_UDP, 187 .expect_policy = &amanda_exp_policy, 188 }, 189 { 190 .name = "amanda", 191 .me = THIS_MODULE, 192 .help = amanda_help, 193 .tuple.src.l3num = AF_INET6, 194 .tuple.src.u.udp.port = cpu_to_be16(10080), 195 .tuple.dst.protonum = IPPROTO_UDP, 196 .expect_policy = &amanda_exp_policy, 197 }, 198}; 199 200static void __exit nf_conntrack_amanda_fini(void) 201{ 202 int i; 203 204 nf_conntrack_helper_unregister(&amanda_helper[0]); 205 nf_conntrack_helper_unregister(&amanda_helper[1]); 206 for (i = 0; i < ARRAY_SIZE(search); i++) 207 textsearch_destroy(search[i].ts); 208} 209 210static int __init nf_conntrack_amanda_init(void) 211{ 212 int ret, i; 213 214 for (i = 0; i < ARRAY_SIZE(search); i++) { 215 search[i].ts = textsearch_prepare(ts_algo, search[i].string, 216 search[i].len, 217 GFP_KERNEL, TS_AUTOLOAD); 218 if (IS_ERR(search[i].ts)) { 219 ret = PTR_ERR(search[i].ts); 220 goto err1; 221 } 222 } 223 ret = nf_conntrack_helper_register(&amanda_helper[0]); 224 if (ret < 0) 225 goto err1; 226 ret = nf_conntrack_helper_register(&amanda_helper[1]); 227 if (ret < 0) 228 goto err2; 229 return 0; 230 231err2: 232 nf_conntrack_helper_unregister(&amanda_helper[0]); 233err1: 234 while (--i >= 0) 235 textsearch_destroy(search[i].ts); 236 237 return ret; 238} 239 240module_init(nf_conntrack_amanda_init); 241module_exit(nf_conntrack_amanda_fini); 242