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   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
  19 #include <net/netfilter/nf_conntrack.h>
  20 #include <net/netfilter/nf_conntrack_expect.h>
  21 #include <net/netfilter/nf_conntrack_ecache.h>
  22 #include <net/netfilter/nf_conntrack_helper.h>
  23 #include <linux/netfilter/nf_conntrack_amanda.h>
  24
  25 static unsigned int master_timeout __read_mostly = 300;
  26 static char *ts_algo = "kmp";
  27
  28 MODULE_AUTHOR("Brian J. Murrell <netfilter@interlinx.bc.ca>");
  29 MODULE_DESCRIPTION("Amanda connection tracking module");
  30 MODULE_LICENSE("GPL");
  31 MODULE_ALIAS("ip_conntrack_amanda");
  32
  33 module_param(master_timeout, uint, 0600);
  34 MODULE_PARM_DESC(master_timeout, "timeout for the master connection");
  35 module_param(ts_algo, charp, 0400);
  36 MODULE_PARM_DESC(ts_algo, "textsearch algorithm to use (default kmp)");
  37
  38 unsigned int (*nf_nat_amanda_hook)(struct sk_buff **pskb,
  39                                    enum ip_conntrack_info ctinfo,
  40                                    unsigned int matchoff,
  41                                    unsigned int matchlen,
  42                                    struct nf_conntrack_expect *exp)
  43                                    __read_mostly;
  44 EXPORT_SYMBOL_GPL(nf_nat_amanda_hook);
  45
  46 enum amanda_strings {
  47         SEARCH_CONNECT,
  48         SEARCH_NEWLINE,
  49         SEARCH_DATA,
  50         SEARCH_MESG,
  51         SEARCH_INDEX,
  52 };
  53
  54 static struct {
  55         char                    *string;
  56         size_t                  len;
  57         struct ts_config        *ts;
  58 } search[] __read_mostly = {
  59         [SEARCH_CONNECT] = {
  60                 .string = "CONNECT ",
  61                 .len    = 8,
  62         },
  63         [SEARCH_NEWLINE] = {
  64                 .string = "\n",
  65                 .len    = 1,
  66         },
  67         [SEARCH_DATA] = {
  68                 .string = "DATA ",
  69                 .len    = 5,
  70         },
  71         [SEARCH_MESG] = {
  72                 .string = "MESG ",
  73                 .len    = 5,
  74         },
  75         [SEARCH_INDEX] = {
  76                 .string = "INDEX ",
  77                 .len    = 6,
  78         },
  79 };
  80
  81 static int amanda_help(struct sk_buff **pskb,
  82                        unsigned int protoff,
  83                        struct nf_conn *ct,
  84                        enum ip_conntrack_info ctinfo)
  85 {
  86         struct ts_state ts;
  87         struct nf_conntrack_expect *exp;
  88         struct nf_conntrack_tuple *tuple;
  89         unsigned int dataoff, start, stop, off, i;
  90         char pbuf[sizeof("65535")], *tmp;
  91         u_int16_t len;
  92         __be16 port;
  93         int family = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num;
  94         int ret = NF_ACCEPT;
  95         typeof(nf_nat_amanda_hook) nf_nat_amanda;
  96
  97         /* Only look at packets from the Amanda server */
  98         if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL)
  99                 return NF_ACCEPT;
 100
 101         /* increase the UDP timeout of the master connection as replies from
 102          * Amanda clients to the server can be quite delayed */
 103         nf_ct_refresh(ct, *pskb, master_timeout * HZ);
 104
 105         /* No data? */
 106         dataoff = protoff + sizeof(struct udphdr);
 107         if (dataoff >= (*pskb)->len) {
 108                 if (net_ratelimit())
 109                         printk("amanda_help: skblen = %u\n", (*pskb)->len);
 110                 return NF_ACCEPT;
 111         }
 112
 113         memset(&ts, 0, sizeof(ts));
 114         start = skb_find_text(*pskb, dataoff, (*pskb)->len,
 115                               search[SEARCH_CONNECT].ts, &ts);
 116         if (start == UINT_MAX)
 117                 goto out;
 118         start += dataoff + search[SEARCH_CONNECT].len;
 119
 120         memset(&ts, 0, sizeof(ts));
 121         stop = skb_find_text(*pskb, start, (*pskb)->len,
 122                              search[SEARCH_NEWLINE].ts, &ts);
 123         if (stop == UINT_MAX)
 124                 goto out;
 125         stop += start;
 126
 127         for (i = SEARCH_DATA; i <= SEARCH_INDEX; i++) {
 128                 memset(&ts, 0, sizeof(ts));
 129                 off = skb_find_text(*pskb, start, stop, search[i].ts, &ts);
 130                 if (off == UINT_MAX)
 131                         continue;
 132                 off += start + search[i].len;
 133
 134                 len = min_t(unsigned int, sizeof(pbuf) - 1, stop - off);
 135                 if (skb_copy_bits(*pskb, off, pbuf, len))
 136                         break;
 137                 pbuf[len] = '\0';
 138
 139                 port = htons(simple_strtoul(pbuf, &tmp, 10));
 140                 len = tmp - pbuf;
 141                 if (port == 0 || len > 5)
 142                         break;
 143
 144                 exp = nf_conntrack_expect_alloc(ct);
 145                 if (exp == NULL) {
 146                         ret = NF_DROP;
 147                         goto out;
 148                 }
 149                 tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
 150                 nf_conntrack_expect_init(exp, family,
 151                                          &tuple->src.u3, &tuple->dst.u3,
 152                                          IPPROTO_TCP, NULL, &port);
 153
 154                 nf_nat_amanda = rcu_dereference(nf_nat_amanda_hook);
 155                 if (nf_nat_amanda && ct->status & IPS_NAT_MASK)
 156                         ret = nf_nat_amanda(pskb, ctinfo, off - dataoff,
 157                                             len, exp);
 158                 else if (nf_conntrack_expect_related(exp) != 0)
 159                         ret = NF_DROP;
 160                 nf_conntrack_expect_put(exp);
 161         }
 162
 163 out:
 164         return ret;
 165 }
 166
 167 static struct nf_conntrack_helper amanda_helper[2] __read_mostly = {
 168         {
 169                 .name                   = "amanda",
 170                 .max_expected           = 3,
 171                 .timeout                = 180,
 172                 .me                     = THIS_MODULE,
 173                 .help                   = amanda_help,
 174                 .tuple.src.l3num        = AF_INET,
 175                 .tuple.src.u.udp.port   = __constant_htons(10080),
 176                 .tuple.dst.protonum     = IPPROTO_UDP,
 177                 .mask.src.l3num         = 0xFFFF,
 178                 .mask.src.u.udp.port    = __constant_htons(0xFFFF),
 179                 .mask.dst.protonum      = 0xFF,
 180         },
 181         {
 182                 .name                   = "amanda",
 183                 .max_expected           = 3,
 184                 .timeout                = 180,
 185                 .me                     = THIS_MODULE,
 186                 .help                   = amanda_help,
 187                 .tuple.src.l3num        = AF_INET6,
 188                 .tuple.src.u.udp.port   = __constant_htons(10080),
 189                 .tuple.dst.protonum     = IPPROTO_UDP,
 190                 .mask.src.l3num         = 0xFFFF,
 191                 .mask.src.u.udp.port    = __constant_htons(0xFFFF),
 192                 .mask.dst.protonum      = 0xFF,
 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         ret = -ENOMEM;
 211         for (i = 0; i < ARRAY_SIZE(search); i++) {
 212                 search[i].ts = textsearch_prepare(ts_algo, search[i].string,
 213                                                   search[i].len,
 214                                                   GFP_KERNEL, TS_AUTOLOAD);
 215                 if (search[i].ts == NULL)
 216                         goto err1;
 217         }
 218         ret = nf_conntrack_helper_register(&amanda_helper[0]);
 219         if (ret < 0)
 220                 goto err1;
 221         ret = nf_conntrack_helper_register(&amanda_helper[1]);
 222         if (ret < 0)
 223                 goto err2;
 224         return 0;
 225
 226 err2:
 227         nf_conntrack_helper_unregister(&amanda_helper[0]);
 228 err1:
 229         for (; i >= 0; i--) {
 230                 if (search[i].ts)
 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);