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net/netfilter/nf_conntrack_irc.c
7.92 KB
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/* 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 * * 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. */ #include <linux/module.h> #include <linux/moduleparam.h> #include <linux/skbuff.h> #include <linux/in.h> |
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#include <linux/ip.h> |
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#include <linux/tcp.h> #include <linux/netfilter.h> |
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#include <linux/slab.h> |
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#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]; |
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static unsigned int ports_c; |
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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); |
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unsigned int (*nf_nat_irc_hook)(struct sk_buff *skb, |
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enum ip_conntrack_info ctinfo, 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"); |
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MODULE_ALIAS_NFCT_HELPER("irc"); |
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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"); |
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static const char *const dccprotos[] = { |
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"SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT " }; #define MINMATCHLEN 5 |
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/* 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 */ |
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static int parse_dcc(char *data, const char *data_end, __be32 *ip, |
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u_int16_t *port, char **ad_beg_p, char **ad_end_p) { |
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char *tmp; |
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/* at least 12: "AAAAAAAA P\1 " */ while (*data++ != ' ') if (data > data_end - 12) return -1; |
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/* 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 == ' ') break; if (tmp > data_end || *tmp != ' ') return -1; |
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*ad_beg_p = data; |
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*ip = cpu_to_be32(simple_strtoul(data, &data, 10)); |
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/* 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; } |
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static int help(struct sk_buff *skb, unsigned int protoff, |
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struct nf_conn *ct, enum ip_conntrack_info ctinfo) { unsigned int dataoff; |
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const struct iphdr *iph; const struct tcphdr *th; struct tcphdr _tcph; const char *data_limit; char *data, *ib_ptr; |
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int dir = CTINFO2DIR(ctinfo); struct nf_conntrack_expect *exp; struct nf_conntrack_tuple *tuple; |
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__be32 dcc_ip; |
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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 + IP_CT_IS_REPLY) return NF_ACCEPT; /* Not a full tcp header? */ |
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th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph); |
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if (th == NULL) return NF_ACCEPT; /* No data? */ dataoff = protoff + th->doff*4; |
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if (dataoff >= skb->len) |
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return NF_ACCEPT; spin_lock_bh(&irc_buffer_lock); |
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ib_ptr = skb_header_pointer(skb, dataoff, skb->len - dataoff, |
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irc_buffer); BUG_ON(ib_ptr == NULL); data = ib_ptr; |
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data_limit = ib_ptr + skb->len - dataoff; |
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/* strlen("\1DCC SENT t AAAAAAAA P\1 ")=24 * 5+MINMATCHLEN+strlen("t AAAAAAAA P\1 ")=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 */ |
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iph = ip_hdr(skb); |
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pr_debug("DCC found in master %pI4:%u %pI4:%u ", &iph->saddr, ntohs(th->source), &iph->daddr, ntohs(th->dest)); |
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for (i = 0; i < ARRAY_SIZE(dccprotos); i++) { if (memcmp(data, dccprotos[i], strlen(dccprotos[i]))) { /* no match */ continue; } data += strlen(dccprotos[i]); |
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pr_debug("DCC %s detected ", dccprotos[i]); |
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/* we have at least * (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid * data left (== 14/13 bytes) */ |
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if (parse_dcc(data, data_limit, &dcc_ip, |
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&dcc_port, &addr_beg_p, &addr_end_p)) { |
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pr_debug("unable to parse dcc command "); |
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continue; } |
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pr_debug("DCC bound ip/port: %pI4:%u ", &dcc_ip, dcc_port); |
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/* dcc_ip can be the internal OR external (NAT'ed) IP */ tuple = &ct->tuplehash[dir].tuple; |
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if (tuple->src.u3.ip != dcc_ip && tuple->dst.u3.ip != dcc_ip) { |
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if (net_ratelimit()) printk(KERN_WARNING |
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"Forged DCC command from %pI4: %pI4:%u ", &tuple->src.u3.ip, &dcc_ip, dcc_port); |
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continue; } |
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exp = nf_ct_expect_alloc(ct); |
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if (exp == NULL) { ret = NF_DROP; goto out; } tuple = &ct->tuplehash[!dir].tuple; port = htons(dcc_port); |
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nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, tuple->src.l3num, |
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NULL, &tuple->dst.u3, IPPROTO_TCP, NULL, &port); |
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nf_nat_irc = rcu_dereference(nf_nat_irc_hook); if (nf_nat_irc && ct->status & IPS_NAT_MASK) |
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ret = nf_nat_irc(skb, ctinfo, |
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addr_beg_p - ib_ptr, addr_end_p - addr_beg_p, exp); |
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else if (nf_ct_expect_related(exp) != 0) |
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ret = NF_DROP; |
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nf_ct_expect_put(exp); |
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goto out; } } out: spin_unlock_bh(&irc_buffer_lock); return ret; } static struct nf_conntrack_helper irc[MAX_PORTS] __read_mostly; static char irc_names[MAX_PORTS][sizeof("irc-65535")] __read_mostly; |
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static struct nf_conntrack_expect_policy irc_exp_policy; |
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static void nf_conntrack_irc_fini(void); static int __init nf_conntrack_irc_init(void) { int i, ret; char *tmpname; if (max_dcc_channels < 1) { |
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printk(KERN_ERR "nf_ct_irc: max_dcc_channels must not be zero "); |
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return -EINVAL; } |
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irc_exp_policy.max_expected = max_dcc_channels; irc_exp_policy.timeout = dcc_timeout; |
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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++) { irc[i].tuple.src.l3num = AF_INET; irc[i].tuple.src.u.tcp.port = htons(ports[i]); irc[i].tuple.dst.protonum = IPPROTO_TCP; |
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irc[i].expect_policy = &irc_exp_policy; |
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irc[i].me = THIS_MODULE; irc[i].help = help; tmpname = &irc_names[i][0]; if (ports[i] == IRC_PORT) sprintf(tmpname, "irc"); else sprintf(tmpname, "irc-%u", i); irc[i].name = tmpname; ret = nf_conntrack_helper_register(&irc[i]); if (ret) { |
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printk(KERN_ERR "nf_ct_irc: failed to register helper " |
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"for pf: %u port: %u ", irc[i].tuple.src.l3num, ports[i]); nf_conntrack_irc_fini(); 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) { int i; for (i = 0; i < ports_c; i++) nf_conntrack_helper_unregister(&irc[i]); kfree(irc_buffer); } module_init(nf_conntrack_irc_init); module_exit(nf_conntrack_irc_fini); |