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 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License 8 * as published by the Free Software Foundation; either version 9 * 2 of the License, or (at your option) any later version. 10 */ 11#include <linux/kernel.h> 12#include <linux/module.h> 13#include <linux/moduleparam.h> 14#include <linux/textsearch.h> 15#include <linux/skbuff.h> 16#include <linux/in.h> 17#include <linux/udp.h> 18#include <linux/netfilter.h> 19#include <linux/gfp.h> 20 21#include <net/netfilter/nf_conntrack.h> 22#include <net/netfilter/nf_conntrack_expect.h> 23#include <net/netfilter/nf_conntrack_ecache.h> 24#include <net/netfilter/nf_conntrack_helper.h> 25#include <linux/netfilter/nf_conntrack_amanda.h> 26 27static unsigned int master_timeout __read_mostly = 300; 28static char *ts_algo = "kmp"; 29 30MODULE_AUTHOR("Brian J. Murrell <netfilter@interlinx.bc.ca>"); 31MODULE_DESCRIPTION("Amanda connection tracking module"); 32MODULE_LICENSE("GPL"); 33MODULE_ALIAS("ip_conntrack_amanda"); 34MODULE_ALIAS_NFCT_HELPER("amanda"); 35 36module_param(master_timeout, uint, 0600); 37MODULE_PARM_DESC(master_timeout, "timeout for the master connection"); 38module_param(ts_algo, charp, 0400); 39MODULE_PARM_DESC(ts_algo, "textsearch algorithm to use (default kmp)"); 40 41unsigned int (*nf_nat_amanda_hook)(struct sk_buff *skb, 42 enum ip_conntrack_info ctinfo, 43 unsigned int matchoff, 44 unsigned int matchlen, 45 struct nf_conntrack_expect *exp) 46 __read_mostly; 47EXPORT_SYMBOL_GPL(nf_nat_amanda_hook); 48 49enum amanda_strings { 50 SEARCH_CONNECT, 51 SEARCH_NEWLINE, 52 SEARCH_DATA, 53 SEARCH_MESG, 54 SEARCH_INDEX, 55}; 56 57static struct { 58 const char *string; 59 size_t len; 60 struct ts_config *ts; 61} search[] __read_mostly = { 62 [SEARCH_CONNECT] = { 63 .string = "CONNECT ", 64 .len = 8, 65 }, 66 [SEARCH_NEWLINE] = { 67 .string = "\n", 68 .len = 1, 69 }, 70 [SEARCH_DATA] = { 71 .string = "DATA ", 72 .len = 5, 73 }, 74 [SEARCH_MESG] = { 75 .string = "MESG ", 76 .len = 5, 77 }, 78 [SEARCH_INDEX] = { 79 .string = "INDEX ", 80 .len = 6, 81 }, 82}; 83 84static int amanda_help(struct sk_buff *skb, 85 unsigned int protoff, 86 struct nf_conn *ct, 87 enum ip_conntrack_info ctinfo) 88{ 89 struct ts_state ts; 90 struct nf_conntrack_expect *exp; 91 struct nf_conntrack_tuple *tuple; 92 unsigned int dataoff, start, stop, off, i; 93 char pbuf[sizeof("65535")], *tmp; 94 u_int16_t len; 95 __be16 port; 96 int ret = NF_ACCEPT; 97 typeof(nf_nat_amanda_hook) nf_nat_amanda; 98 99 /* Only look at packets from the Amanda server */ 100 if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) 101 return NF_ACCEPT; 102 103 /* increase the UDP timeout of the master connection as replies from 104 * Amanda clients to the server can be quite delayed */ 105 nf_ct_refresh(ct, skb, master_timeout * HZ); 106 107 /* No data? */ 108 dataoff = protoff + sizeof(struct udphdr); 109 if (dataoff >= skb->len) { 110 if (net_ratelimit()) 111 printk(KERN_ERR "amanda_help: skblen = %u\n", skb->len); 112 return NF_ACCEPT; 113 } 114 115 memset(&ts, 0, sizeof(ts)); 116 start = skb_find_text(skb, dataoff, skb->len, 117 search[SEARCH_CONNECT].ts, &ts); 118 if (start == UINT_MAX) 119 goto out; 120 start += dataoff + search[SEARCH_CONNECT].len; 121 122 memset(&ts, 0, sizeof(ts)); 123 stop = skb_find_text(skb, start, skb->len, 124 search[SEARCH_NEWLINE].ts, &ts); 125 if (stop == UINT_MAX) 126 goto out; 127 stop += start; 128 129 for (i = SEARCH_DATA; i <= SEARCH_INDEX; i++) { 130 memset(&ts, 0, sizeof(ts)); 131 off = skb_find_text(skb, start, stop, search[i].ts, &ts); 132 if (off == UINT_MAX) 133 continue; 134 off += start + search[i].len; 135 136 len = min_t(unsigned int, sizeof(pbuf) - 1, stop - off); 137 if (skb_copy_bits(skb, off, pbuf, len)) 138 break; 139 pbuf[len] = '\0'; 140 141 port = htons(simple_strtoul(pbuf, &tmp, 10)); 142 len = tmp - pbuf; 143 if (port == 0 || len > 5) 144 break; 145 146 exp = nf_ct_expect_alloc(ct); 147 if (exp == NULL) { 148 ret = NF_DROP; 149 goto out; 150 } 151 tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple; 152 nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, 153 nf_ct_l3num(ct), 154 &tuple->src.u3, &tuple->dst.u3, 155 IPPROTO_TCP, NULL, &port); 156 157 nf_nat_amanda = rcu_dereference(nf_nat_amanda_hook); 158 if (nf_nat_amanda && ct->status & IPS_NAT_MASK) 159 ret = nf_nat_amanda(skb, ctinfo, off - dataoff, 160 len, exp); 161 else if (nf_ct_expect_related(exp) != 0) 162 ret = NF_DROP; 163 nf_ct_expect_put(exp); 164 } 165 166out: 167 return ret; 168} 169 170static const struct nf_conntrack_expect_policy amanda_exp_policy = { 171 .max_expected = 3, 172 .timeout = 180, 173}; 174 175static struct nf_conntrack_helper amanda_helper[2] __read_mostly = { 176 { 177 .name = "amanda", 178 .me = THIS_MODULE, 179 .help = amanda_help, 180 .tuple.src.l3num = AF_INET, 181 .tuple.src.u.udp.port = cpu_to_be16(10080), 182 .tuple.dst.protonum = IPPROTO_UDP, 183 .expect_policy = &amanda_exp_policy, 184 }, 185 { 186 .name = "amanda", 187 .me = THIS_MODULE, 188 .help = amanda_help, 189 .tuple.src.l3num = AF_INET6, 190 .tuple.src.u.udp.port = cpu_to_be16(10080), 191 .tuple.dst.protonum = IPPROTO_UDP, 192 .expect_policy = &amanda_exp_policy, 193 }, 194}; 195 196static void __exit nf_conntrack_amanda_fini(void) 197{ 198 int i; 199 200 nf_conntrack_helper_unregister(&amanda_helper[0]); 201 nf_conntrack_helper_unregister(&amanda_helper[1]); 202 for (i = 0; i < ARRAY_SIZE(search); i++) 203 textsearch_destroy(search[i].ts); 204} 205 206static int __init nf_conntrack_amanda_init(void) 207{ 208 int ret, i; 209 210 for (i = 0; i < ARRAY_SIZE(search); i++) { 211 search[i].ts = textsearch_prepare(ts_algo, search[i].string, 212 search[i].len, 213 GFP_KERNEL, TS_AUTOLOAD); 214 if (IS_ERR(search[i].ts)) { 215 ret = PTR_ERR(search[i].ts); 216 goto err1; 217 } 218 } 219 ret = nf_conntrack_helper_register(&amanda_helper[0]); 220 if (ret < 0) 221 goto err1; 222 ret = nf_conntrack_helper_register(&amanda_helper[1]); 223 if (ret < 0) 224 goto err2; 225 return 0; 226 227err2: 228 nf_conntrack_helper_unregister(&amanda_helper[0]); 229err1: 230 while (--i >= 0) 231 textsearch_destroy(search[i].ts); 232 233 return ret; 234} 235 236module_init(nf_conntrack_amanda_init); 237module_exit(nf_conntrack_amanda_fini); 238