nf_conntrack_amanda.c (6032B)
1// SPDX-License-Identifier: GPL-2.0-or-later 2/* Amanda extension for IP connection tracking 3 * 4 * (C) 2002 by Brian J. Murrell <netfilter@interlinx.bc.ca> 5 * based on HW's ip_conntrack_irc.c as well as other modules 6 * (C) 2006 Patrick McHardy <kaber@trash.net> 7 */ 8#include <linux/kernel.h> 9#include <linux/module.h> 10#include <linux/moduleparam.h> 11#include <linux/textsearch.h> 12#include <linux/skbuff.h> 13#include <linux/in.h> 14#include <linux/udp.h> 15#include <linux/netfilter.h> 16#include <linux/gfp.h> 17 18#include <net/netfilter/nf_conntrack.h> 19#include <net/netfilter/nf_conntrack_expect.h> 20#include <net/netfilter/nf_conntrack_ecache.h> 21#include <net/netfilter/nf_conntrack_helper.h> 22#include <linux/netfilter/nf_conntrack_amanda.h> 23 24static unsigned int master_timeout __read_mostly = 300; 25static char *ts_algo = "kmp"; 26 27#define HELPER_NAME "amanda" 28 29MODULE_AUTHOR("Brian J. Murrell <netfilter@interlinx.bc.ca>"); 30MODULE_DESCRIPTION("Amanda connection tracking module"); 31MODULE_LICENSE("GPL"); 32MODULE_ALIAS("ip_conntrack_amanda"); 33MODULE_ALIAS_NFCT_HELPER(HELPER_NAME); 34 35module_param(master_timeout, uint, 0600); 36MODULE_PARM_DESC(master_timeout, "timeout for the master connection"); 37module_param(ts_algo, charp, 0400); 38MODULE_PARM_DESC(ts_algo, "textsearch algorithm to use (default kmp)"); 39 40unsigned int (*nf_nat_amanda_hook)(struct sk_buff *skb, 41 enum ip_conntrack_info ctinfo, 42 unsigned int protoff, 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 SEARCH_STATE, 56}; 57 58static struct { 59 const char *string; 60 size_t len; 61 struct ts_config *ts; 62} search[] __read_mostly = { 63 [SEARCH_CONNECT] = { 64 .string = "CONNECT ", 65 .len = 8, 66 }, 67 [SEARCH_NEWLINE] = { 68 .string = "\n", 69 .len = 1, 70 }, 71 [SEARCH_DATA] = { 72 .string = "DATA ", 73 .len = 5, 74 }, 75 [SEARCH_MESG] = { 76 .string = "MESG ", 77 .len = 5, 78 }, 79 [SEARCH_INDEX] = { 80 .string = "INDEX ", 81 .len = 6, 82 }, 83 [SEARCH_STATE] = { 84 .string = "STATE ", 85 .len = 6, 86 }, 87}; 88 89static int amanda_help(struct sk_buff *skb, 90 unsigned int protoff, 91 struct nf_conn *ct, 92 enum ip_conntrack_info ctinfo) 93{ 94 struct nf_conntrack_expect *exp; 95 struct nf_conntrack_tuple *tuple; 96 unsigned int dataoff, start, stop, off, i; 97 char pbuf[sizeof("65535")], *tmp; 98 u_int16_t len; 99 __be16 port; 100 int ret = NF_ACCEPT; 101 typeof(nf_nat_amanda_hook) nf_nat_amanda; 102 103 /* Only look at packets from the Amanda server */ 104 if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) 105 return NF_ACCEPT; 106 107 /* increase the UDP timeout of the master connection as replies from 108 * Amanda clients to the server can be quite delayed */ 109 nf_ct_refresh(ct, skb, master_timeout * HZ); 110 111 /* No data? */ 112 dataoff = protoff + sizeof(struct udphdr); 113 if (dataoff >= skb->len) { 114 net_err_ratelimited("amanda_help: skblen = %u\n", skb->len); 115 return NF_ACCEPT; 116 } 117 118 start = skb_find_text(skb, dataoff, skb->len, 119 search[SEARCH_CONNECT].ts); 120 if (start == UINT_MAX) 121 goto out; 122 start += dataoff + search[SEARCH_CONNECT].len; 123 124 stop = skb_find_text(skb, start, skb->len, 125 search[SEARCH_NEWLINE].ts); 126 if (stop == UINT_MAX) 127 goto out; 128 stop += start; 129 130 for (i = SEARCH_DATA; i <= SEARCH_STATE; i++) { 131 off = skb_find_text(skb, start, stop, search[i].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 nf_ct_helper_log(skb, ct, "cannot alloc expectation"); 149 ret = NF_DROP; 150 goto out; 151 } 152 tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple; 153 nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, 154 nf_ct_l3num(ct), 155 &tuple->src.u3, &tuple->dst.u3, 156 IPPROTO_TCP, NULL, &port); 157 158 nf_nat_amanda = rcu_dereference(nf_nat_amanda_hook); 159 if (nf_nat_amanda && ct->status & IPS_NAT_MASK) 160 ret = nf_nat_amanda(skb, ctinfo, protoff, 161 off - dataoff, len, exp); 162 else if (nf_ct_expect_related(exp, 0) != 0) { 163 nf_ct_helper_log(skb, ct, "cannot add expectation"); 164 ret = NF_DROP; 165 } 166 nf_ct_expect_put(exp); 167 } 168 169out: 170 return ret; 171} 172 173static const struct nf_conntrack_expect_policy amanda_exp_policy = { 174 .max_expected = 4, 175 .timeout = 180, 176}; 177 178static struct nf_conntrack_helper amanda_helper[2] __read_mostly = { 179 { 180 .name = HELPER_NAME, 181 .me = THIS_MODULE, 182 .help = amanda_help, 183 .tuple.src.l3num = AF_INET, 184 .tuple.src.u.udp.port = cpu_to_be16(10080), 185 .tuple.dst.protonum = IPPROTO_UDP, 186 .expect_policy = &amanda_exp_policy, 187 .nat_mod_name = NF_NAT_HELPER_NAME(HELPER_NAME), 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 .nat_mod_name = NF_NAT_HELPER_NAME(HELPER_NAME), 198 }, 199}; 200 201static void __exit nf_conntrack_amanda_fini(void) 202{ 203 int i; 204 205 nf_conntrack_helpers_unregister(amanda_helper, 206 ARRAY_SIZE(amanda_helper)); 207 for (i = 0; i < ARRAY_SIZE(search); i++) 208 textsearch_destroy(search[i].ts); 209} 210 211static int __init nf_conntrack_amanda_init(void) 212{ 213 int ret, i; 214 215 NF_CT_HELPER_BUILD_BUG_ON(0); 216 217 for (i = 0; i < ARRAY_SIZE(search); i++) { 218 search[i].ts = textsearch_prepare(ts_algo, search[i].string, 219 search[i].len, 220 GFP_KERNEL, TS_AUTOLOAD); 221 if (IS_ERR(search[i].ts)) { 222 ret = PTR_ERR(search[i].ts); 223 goto err1; 224 } 225 } 226 ret = nf_conntrack_helpers_register(amanda_helper, 227 ARRAY_SIZE(amanda_helper)); 228 if (ret < 0) 229 goto err1; 230 return 0; 231 232err1: 233 while (--i >= 0) 234 textsearch_destroy(search[i].ts); 235 236 return ret; 237} 238 239module_init(nf_conntrack_amanda_init); 240module_exit(nf_conntrack_amanda_fini);