// SPDX-License-Identifier: GPL-2.0-or-later
/* Amanda extension for IP connection tracking
*
* (C) 2002 by Brian J. Murrell <[email protected]>
* based on HW's ip_conntrack_irc.c as well as other modules
* (C) 2006 Patrick McHardy <[email protected]>
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/textsearch.h>
#include <linux/skbuff.h>
#include <linux/in.h>
#include <linux/udp.h>
#include <linux/netfilter.h>
#include <linux/gfp.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_expect.h>
#include <net/netfilter/nf_conntrack_ecache.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <linux/netfilter/nf_conntrack_amanda.h>
static unsigned int master_timeout __read_mostly = 300;
static char *ts_algo = "kmp";
#define HELPER_NAME "amanda"
MODULE_AUTHOR("Brian J. Murrell <[email protected]>");
MODULE_DESCRIPTION("Amanda connection tracking module");
MODULE_LICENSE("GPL");
MODULE_ALIAS("ip_conntrack_amanda");
MODULE_ALIAS_NFCT_HELPER(HELPER_NAME);
module_param(master_timeout, uint, 0600);
MODULE_PARM_DESC(master_timeout, "timeout for the master connection");
module_param(ts_algo, charp, 0400);
MODULE_PARM_DESC(ts_algo, "textsearch algorithm to use (default kmp)");
unsigned int (*nf_nat_amanda_hook)(struct sk_buff *skb,
enum ip_conntrack_info ctinfo,
unsigned int protoff,
unsigned int matchoff,
unsigned int matchlen,
struct nf_conntrack_expect *exp)
__read_mostly;
EXPORT_SYMBOL_GPL(nf_nat_amanda_hook);
enum amanda_strings {
SEARCH_CONNECT,
SEARCH_NEWLINE,
SEARCH_DATA,
SEARCH_MESG,
SEARCH_INDEX,
SEARCH_STATE,
};
static struct {
const char *string;
size_t len;
struct ts_config *ts;
} search[] __read_mostly = {
[SEARCH_CONNECT] = {
.string = "CONNECT ",
.len = 8,
},
[SEARCH_NEWLINE] = {
.string = "\n",
.len = 1,
},
[SEARCH_DATA] = {
.string = "DATA ",
.len = 5,
},
[SEARCH_MESG] = {
.string = "MESG ",
.len = 5,
},
[SEARCH_INDEX] = {
.string = "INDEX ",
.len = 6,
},
[SEARCH_STATE] = {
.string = "STATE ",
.len = 6,
},
};
static int amanda_help(struct sk_buff *skb,
unsigned int protoff,
struct nf_conn *ct,
enum ip_conntrack_info ctinfo)
{
struct nf_conntrack_expect *exp;
struct nf_conntrack_tuple *tuple;
unsigned int dataoff, start, stop, off, i;
char pbuf[sizeof("65535")], *tmp;
u_int16_t len;
__be16 port;
int ret = NF_ACCEPT;
typeof(nf_nat_amanda_hook) nf_nat_amanda;
/* Only look at packets from the Amanda server */
if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL)
return NF_ACCEPT;
/* increase the UDP timeout of the master connection as replies from
* Amanda clients to the server can be quite delayed */
nf_ct_refresh(ct, skb, master_timeout * HZ);
/* No data? */
dataoff = protoff + sizeof(struct udphdr);
if (dataoff >= skb->len) {
net_err_ratelimited("amanda_help: skblen = %u\n", skb->len);
return NF_ACCEPT;
}
start = skb_find_text(skb, dataoff, skb->len,
search[SEARCH_CONNECT].ts);
if (start == UINT_MAX)
goto out;
start += dataoff + search[SEARCH_CONNECT].len;
stop = skb_find_text(skb, start, skb->len,
search[SEARCH_NEWLINE].ts);
if (stop == UINT_MAX)
goto out;
stop += start;
for (i = SEARCH_DATA; i <= SEARCH_STATE; i++) {
off = skb_find_text(skb, start, stop, search[i].ts);
if (off == UINT_MAX)
continue;
off += start + search[i].len;
len = min_t(unsigned int, sizeof(pbuf) - 1, stop - off);
if (skb_copy_bits(skb, off, pbuf, len))
break;
pbuf[len] = '\0';
port = htons(simple_strtoul(pbuf, &tmp, 10));
len = tmp - pbuf;
if (port == 0 || len > 5)
break;
exp = nf_ct_expect_alloc(ct);
if (exp == NULL) {
nf_ct_helper_log(skb, ct, "cannot alloc expectation");
ret = NF_DROP;
goto out;
}
tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT,
nf_ct_l3num(ct),
&tuple->src.u3, &tuple->dst.u3,
IPPROTO_TCP, NULL, &port);
nf_nat_amanda = rcu_dereference(nf_nat_amanda_hook);
if (nf_nat_amanda && ct->status & IPS_NAT_MASK)
ret = nf_nat_amanda(skb, ctinfo, protoff,
off - dataoff, len, exp);
else if (nf_ct_expect_related(exp, 0) != 0) {
nf_ct_helper_log(skb, ct, "cannot add expectation");
ret = NF_DROP;
}
nf_ct_expect_put(exp);
}
out:
return ret;
}
static const struct nf_conntrack_expect_policy amanda_exp_policy = {
.max_expected = 4,
.timeout = 180,
};
static struct nf_conntrack_helper amanda_helper[2] __read_mostly = {
{
.name = HELPER_NAME,
.me = THIS_MODULE,
.help = amanda_help,
.tuple.src.l3num = AF_INET,
.tuple.src.u.udp.port = cpu_to_be16(10080),
.tuple.dst.protonum = IPPROTO_UDP,
.expect_policy = &amanda_exp_policy,
.nat_mod_name = NF_NAT_HELPER_NAME(HELPER_NAME),
},
{
.name = "amanda",
.me = THIS_MODULE,
.help = amanda_help,
.tuple.src.l3num = AF_INET6,
.tuple.src.u.udp.port = cpu_to_be16(10080),
.tuple.dst.protonum = IPPROTO_UDP,
.expect_policy = &amanda_exp_policy,
.nat_mod_name = NF_NAT_HELPER_NAME(HELPER_NAME),
},
};
static void __exit nf_conntrack_amanda_fini(void)
{
int i;
nf_conntrack_helpers_unregister(amanda_helper,
ARRAY_SIZE(amanda_helper));
for (i = 0; i < ARRAY_SIZE(search); i++)
textsearch_destroy(search[i].ts);
}
static int __init nf_conntrack_amanda_init(void)
{
int ret, i;
NF_CT_HELPER_BUILD_BUG_ON(0);
for (i = 0; i < ARRAY_SIZE(search); i++) {
search[i].ts = textsearch_prepare(ts_algo, search[i].string,
search[i].len,
GFP_KERNEL, TS_AUTOLOAD);
if (IS_ERR(search[i].ts)) {
ret = PTR_ERR(search[i].ts);
goto err1;
}
}
ret = nf_conntrack_helpers_register(amanda_helper,
ARRAY_SIZE(amanda_helper));
if (ret < 0)
goto err1;
return 0;
err1:
while (--i >= 0)
textsearch_destroy(search[i].ts);
return ret;
}
module_init(nf_conntrack_amanda_init);
module_exit(nf_conntrack_amanda_fini);
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