| /* IRC extension for IP connection tracking, Version 1.21 |
| * (C) 2000-2002 by Harald Welte <laforge@gnumonks.org> |
| * based on RR's ip_conntrack_ftp.c |
| * (C) 2006-2012 Patrick McHardy <kaber@trash.net> |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License |
| * as published by the Free Software Foundation; either version |
| * 2 of the License, or (at your option) any later version. |
| */ |
| |
| #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| |
| #include <linux/module.h> |
| #include <linux/moduleparam.h> |
| #include <linux/skbuff.h> |
| #include <linux/in.h> |
| #include <linux/ip.h> |
| #include <linux/tcp.h> |
| #include <linux/netfilter.h> |
| #include <linux/slab.h> |
| |
| #include <net/netfilter/nf_conntrack.h> |
| #include <net/netfilter/nf_conntrack_expect.h> |
| #include <net/netfilter/nf_conntrack_helper.h> |
| #include <linux/netfilter/nf_conntrack_irc.h> |
| |
| #define MAX_PORTS 8 |
| static unsigned short ports[MAX_PORTS]; |
| static unsigned int ports_c; |
| static unsigned int max_dcc_channels = 8; |
| static unsigned int dcc_timeout __read_mostly = 300; |
| /* This is slow, but it's simple. --RR */ |
| static char *irc_buffer; |
| static DEFINE_SPINLOCK(irc_buffer_lock); |
| |
| unsigned int (*nf_nat_irc_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_irc_hook); |
| |
| MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); |
| MODULE_DESCRIPTION("IRC (DCC) connection tracking helper"); |
| MODULE_LICENSE("GPL"); |
| MODULE_ALIAS("ip_conntrack_irc"); |
| MODULE_ALIAS_NFCT_HELPER("irc"); |
| |
| module_param_array(ports, ushort, &ports_c, 0400); |
| MODULE_PARM_DESC(ports, "port numbers of IRC servers"); |
| module_param(max_dcc_channels, uint, 0400); |
| MODULE_PARM_DESC(max_dcc_channels, "max number of expected DCC channels per " |
| "IRC session"); |
| module_param(dcc_timeout, uint, 0400); |
| MODULE_PARM_DESC(dcc_timeout, "timeout on for unestablished DCC channels"); |
| |
| static const char *const dccprotos[] = { |
| "SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT " |
| }; |
| |
| #define MINMATCHLEN 5 |
| |
| /* tries to get the ip_addr and port out of a dcc command |
| * return value: -1 on failure, 0 on success |
| * data pointer to first byte of DCC command data |
| * data_end pointer to last byte of dcc command data |
| * ip returns parsed ip of dcc command |
| * port returns parsed port of dcc command |
| * ad_beg_p returns pointer to first byte of addr data |
| * ad_end_p returns pointer to last byte of addr data |
| */ |
| static int parse_dcc(char *data, const char *data_end, __be32 *ip, |
| u_int16_t *port, char **ad_beg_p, char **ad_end_p) |
| { |
| char *tmp; |
| |
| /* at least 12: "AAAAAAAA P\1\n" */ |
| while (*data++ != ' ') |
| if (data > data_end - 12) |
| return -1; |
| |
| /* Make sure we have a newline character within the packet boundaries |
| * because simple_strtoul parses until the first invalid character. */ |
| for (tmp = data; tmp <= data_end; tmp++) |
| if (*tmp == '\n') |
| break; |
| if (tmp > data_end || *tmp != '\n') |
| return -1; |
| |
| *ad_beg_p = data; |
| *ip = cpu_to_be32(simple_strtoul(data, &data, 10)); |
| |
| /* skip blanks between ip and port */ |
| while (*data == ' ') { |
| if (data >= data_end) |
| return -1; |
| data++; |
| } |
| |
| *port = simple_strtoul(data, &data, 10); |
| *ad_end_p = data; |
| |
| return 0; |
| } |
| |
| static int help(struct sk_buff *skb, unsigned int protoff, |
| struct nf_conn *ct, enum ip_conntrack_info ctinfo) |
| { |
| unsigned int dataoff; |
| const struct iphdr *iph; |
| const struct tcphdr *th; |
| struct tcphdr _tcph; |
| const char *data_limit; |
| char *data, *ib_ptr; |
| int dir = CTINFO2DIR(ctinfo); |
| struct nf_conntrack_expect *exp; |
| struct nf_conntrack_tuple *tuple; |
| __be32 dcc_ip; |
| u_int16_t dcc_port; |
| __be16 port; |
| int i, ret = NF_ACCEPT; |
| char *addr_beg_p, *addr_end_p; |
| typeof(nf_nat_irc_hook) nf_nat_irc; |
| |
| /* If packet is coming from IRC server */ |
| if (dir == IP_CT_DIR_REPLY) |
| return NF_ACCEPT; |
| |
| /* Until there's been traffic both ways, don't look in packets. */ |
| if (ctinfo != IP_CT_ESTABLISHED && ctinfo != IP_CT_ESTABLISHED_REPLY) |
| return NF_ACCEPT; |
| |
| /* Not a full tcp header? */ |
| th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph); |
| if (th == NULL) |
| return NF_ACCEPT; |
| |
| /* No data? */ |
| dataoff = protoff + th->doff*4; |
| if (dataoff >= skb->len) |
| return NF_ACCEPT; |
| |
| spin_lock_bh(&irc_buffer_lock); |
| ib_ptr = skb_header_pointer(skb, dataoff, skb->len - dataoff, |
| irc_buffer); |
| BUG_ON(ib_ptr == NULL); |
| |
| data = ib_ptr; |
| data_limit = ib_ptr + skb->len - dataoff; |
| |
| /* strlen("\1DCC SENT t AAAAAAAA P\1\n")=24 |
| * 5+MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=14 */ |
| while (data < data_limit - (19 + MINMATCHLEN)) { |
| if (memcmp(data, "\1DCC ", 5)) { |
| data++; |
| continue; |
| } |
| data += 5; |
| /* we have at least (19+MINMATCHLEN)-5 bytes valid data left */ |
| |
| iph = ip_hdr(skb); |
| pr_debug("DCC found in master %pI4:%u %pI4:%u\n", |
| &iph->saddr, ntohs(th->source), |
| &iph->daddr, ntohs(th->dest)); |
| |
| for (i = 0; i < ARRAY_SIZE(dccprotos); i++) { |
| if (memcmp(data, dccprotos[i], strlen(dccprotos[i]))) { |
| /* no match */ |
| continue; |
| } |
| data += strlen(dccprotos[i]); |
| pr_debug("DCC %s detected\n", dccprotos[i]); |
| |
| /* we have at least |
| * (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid |
| * data left (== 14/13 bytes) */ |
| if (parse_dcc(data, data_limit, &dcc_ip, |
| &dcc_port, &addr_beg_p, &addr_end_p)) { |
| pr_debug("unable to parse dcc command\n"); |
| continue; |
| } |
| |
| pr_debug("DCC bound ip/port: %pI4:%u\n", |
| &dcc_ip, dcc_port); |
| |
| /* dcc_ip can be the internal OR external (NAT'ed) IP */ |
| tuple = &ct->tuplehash[dir].tuple; |
| if (tuple->src.u3.ip != dcc_ip && |
| tuple->dst.u3.ip != dcc_ip) { |
| net_warn_ratelimited("Forged DCC command from %pI4: %pI4:%u\n", |
| &tuple->src.u3.ip, |
| &dcc_ip, dcc_port); |
| continue; |
| } |
| |
| 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[!dir].tuple; |
| port = htons(dcc_port); |
| nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, |
| tuple->src.l3num, |
| NULL, &tuple->dst.u3, |
| IPPROTO_TCP, NULL, &port); |
| |
| nf_nat_irc = rcu_dereference(nf_nat_irc_hook); |
| if (nf_nat_irc && ct->status & IPS_NAT_MASK) |
| ret = nf_nat_irc(skb, ctinfo, protoff, |
| addr_beg_p - ib_ptr, |
| addr_end_p - addr_beg_p, |
| exp); |
| else if (nf_ct_expect_related(exp) != 0) { |
| nf_ct_helper_log(skb, ct, |
| "cannot add expectation"); |
| ret = NF_DROP; |
| } |
| nf_ct_expect_put(exp); |
| goto out; |
| } |
| } |
| out: |
| spin_unlock_bh(&irc_buffer_lock); |
| return ret; |
| } |
| |
| static struct nf_conntrack_helper irc[MAX_PORTS] __read_mostly; |
| static struct nf_conntrack_expect_policy irc_exp_policy; |
| |
| static void nf_conntrack_irc_fini(void); |
| |
| static int __init nf_conntrack_irc_init(void) |
| { |
| int i, ret; |
| |
| if (max_dcc_channels < 1) { |
| pr_err("max_dcc_channels must not be zero\n"); |
| return -EINVAL; |
| } |
| |
| if (max_dcc_channels > NF_CT_EXPECT_MAX_CNT) { |
| pr_err("max_dcc_channels must not be more than %u\n", |
| NF_CT_EXPECT_MAX_CNT); |
| return -EINVAL; |
| } |
| |
| irc_exp_policy.max_expected = max_dcc_channels; |
| irc_exp_policy.timeout = dcc_timeout; |
| |
| irc_buffer = kmalloc(65536, GFP_KERNEL); |
| if (!irc_buffer) |
| return -ENOMEM; |
| |
| /* If no port given, default to standard irc port */ |
| if (ports_c == 0) |
| ports[ports_c++] = IRC_PORT; |
| |
| for (i = 0; i < ports_c; i++) { |
| nf_ct_helper_init(&irc[i], AF_INET, IPPROTO_TCP, "irc", |
| IRC_PORT, ports[i], i, &irc_exp_policy, |
| 0, help, NULL, THIS_MODULE); |
| } |
| |
| ret = nf_conntrack_helpers_register(&irc[0], ports_c); |
| if (ret) { |
| pr_err("failed to register helpers\n"); |
| kfree(irc_buffer); |
| return ret; |
| } |
| |
| return 0; |
| } |
| |
| /* This function is intentionally _NOT_ defined as __exit, because |
| * it is needed by the init function */ |
| static void nf_conntrack_irc_fini(void) |
| { |
| nf_conntrack_helpers_unregister(irc, ports_c); |
| kfree(irc_buffer); |
| } |
| |
| module_init(nf_conntrack_irc_init); |
| module_exit(nf_conntrack_irc_fini); |