| // SPDX-License-Identifier: GPL-2.0-or-later |
| /* Amanda extension for IP connection tracking |
| * |
| * (C) 2002 by Brian J. Murrell <netfilter@interlinx.bc.ca> |
| * based on HW's ip_conntrack_irc.c as well as other modules |
| * (C) 2006 Patrick McHardy <kaber@trash.net> |
| */ |
| #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 <netfilter@interlinx.bc.ca>"); |
| 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); |