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 28 static unsigned int master_timeout __read_mostly = 300; 29 static char *ts_algo = "kmp"; 30 31 MODULE_AUTHOR("Brian J. Murrell <netfilter@interlinx.bc.ca>"); 32 MODULE_DESCRIPTION("Amanda connection tracking module"); 33 MODULE_LICENSE("GPL"); 34 MODULE_ALIAS("ip_conntrack_amanda"); 35 MODULE_ALIAS_NFCT_HELPER("amanda"); 36 37 module_param(master_timeout, uint, 0600); 38 MODULE_PARM_DESC(master_timeout, "timeout for the master connection"); 39 module_param(ts_algo, charp, 0400); 40 MODULE_PARM_DESC(ts_algo, "textsearch algorithm to use (default kmp)"); 41 42 unsigned 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; 49 EXPORT_SYMBOL_GPL(nf_nat_amanda_hook); 50 51 enum amanda_strings { 52 SEARCH_CONNECT, 53 SEARCH_NEWLINE, 54 SEARCH_DATA, 55 SEARCH_MESG, 56 SEARCH_INDEX, 57 }; 58 59 static 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 86 static 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 nf_conntrack_expect *exp; 92 struct nf_conntrack_tuple *tuple; 93 unsigned int dataoff, start, stop, off, i; 94 char pbuf[sizeof("65535")], *tmp; 95 u_int16_t len; 96 __be16 port; 97 int ret = NF_ACCEPT; 98 typeof(nf_nat_amanda_hook) nf_nat_amanda; 99 100 /* Only look at packets from the Amanda server */ 101 if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) 102 return NF_ACCEPT; 103 104 /* increase the UDP timeout of the master connection as replies from 105 * Amanda clients to the server can be quite delayed */ 106 nf_ct_refresh(ct, skb, master_timeout * HZ); 107 108 /* No data? */ 109 dataoff = protoff + sizeof(struct udphdr); 110 if (dataoff >= skb->len) { 111 net_err_ratelimited("amanda_help: skblen = %u\n", skb->len); 112 return NF_ACCEPT; 113 } 114 115 start = skb_find_text(skb, dataoff, skb->len, 116 search[SEARCH_CONNECT].ts); 117 if (start == UINT_MAX) 118 goto out; 119 start += dataoff + search[SEARCH_CONNECT].len; 120 121 stop = skb_find_text(skb, start, skb->len, 122 search[SEARCH_NEWLINE].ts); 123 if (stop == UINT_MAX) 124 goto out; 125 stop += start; 126 127 for (i = SEARCH_DATA; i <= SEARCH_INDEX; i++) { 128 off = skb_find_text(skb, start, stop, search[i].ts); 129 if (off == UINT_MAX) 130 continue; 131 off += start + search[i].len; 132 133 len = min_t(unsigned int, sizeof(pbuf) - 1, stop - off); 134 if (skb_copy_bits(skb, off, pbuf, len)) 135 break; 136 pbuf[len] = '\0'; 137 138 port = htons(simple_strtoul(pbuf, &tmp, 10)); 139 len = tmp - pbuf; 140 if (port == 0 || len > 5) 141 break; 142 143 exp = nf_ct_expect_alloc(ct); 144 if (exp == NULL) { 145 nf_ct_helper_log(skb, ct, "cannot alloc expectation"); 146 ret = NF_DROP; 147 goto out; 148 } 149 tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple; 150 nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, 151 nf_ct_l3num(ct), 152 &tuple->src.u3, &tuple->dst.u3, 153 IPPROTO_TCP, NULL, &port); 154 155 nf_nat_amanda = rcu_dereference(nf_nat_amanda_hook); 156 if (nf_nat_amanda && ct->status & IPS_NAT_MASK) 157 ret = nf_nat_amanda(skb, ctinfo, protoff, 158 off - dataoff, len, exp); 159 else if (nf_ct_expect_related(exp) != 0) { 160 nf_ct_helper_log(skb, ct, "cannot add expectation"); 161 ret = NF_DROP; 162 } 163 nf_ct_expect_put(exp); 164 } 165 166 out: 167 return ret; 168 } 169 170 static const struct nf_conntrack_expect_policy amanda_exp_policy = { 171 .max_expected = 3, 172 .timeout = 180, 173 }; 174 175 static 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 }; 195 196 static 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 } 205 206 static 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; 226 227 err2: 228 nf_conntrack_helper_unregister(&amanda_helper[0]); 229 err1: 230 while (--i >= 0) 231 textsearch_destroy(search[i].ts); 232 233 return ret; 234 } 235 236 module_init(nf_conntrack_amanda_init); 237 module_exit(nf_conntrack_amanda_fini); 238