diff options
Diffstat (limited to 'release/src/linux/linux/net/ipv4/netfilter/ipt_connlimit.c')
| -rw-r--r-- | release/src/linux/linux/net/ipv4/netfilter/ipt_connlimit.c | 222 |
1 files changed, 222 insertions, 0 deletions
diff --git a/release/src/linux/linux/net/ipv4/netfilter/ipt_connlimit.c b/release/src/linux/linux/net/ipv4/netfilter/ipt_connlimit.c new file mode 100644 index 00000000..abf8efff --- /dev/null +++ b/release/src/linux/linux/net/ipv4/netfilter/ipt_connlimit.c @@ -0,0 +1,222 @@ +/* + * netfilter module to limit the number of parallel tcp + * connections per IP address. + * (c) 2000 Gerd Knorr <kraxel@bytesex.org> + * Nov 2002: Martin Bene <martin.bene@icomedias.com>: + * only ignore TIME_WAIT or gone connections + * + * based on ... + * + * Kernel module to match connection tracking information. + * GPL (C) 1999 Rusty Russell (rusty@rustcorp.com.au). + */ +#include <linux/module.h> +#include <linux/skbuff.h> +#include <linux/list.h> +#include <linux/version.h> +#include <linux/netfilter_ipv4/ip_conntrack.h> +#include <linux/netfilter_ipv4/ip_conntrack_core.h> +#include <linux/netfilter_ipv4/ip_conntrack_tcp.h> +#include <linux/netfilter_ipv4/ip_tables.h> +#include <linux/netfilter_ipv4/ipt_connlimit.h> + +#define DEBUG 0 + +MODULE_LICENSE("GPL"); + +/* we'll save the tuples of all connections we care about */ +struct ipt_connlimit_conn +{ + struct list_head list; + struct ip_conntrack_tuple tuple; +}; + +struct ipt_connlimit_data { + spinlock_t lock; + struct list_head iphash[256]; +}; + +static inline unsigned ipt_iphash(const unsigned addr) +{ + return ((addr ^ (addr >> 8) ^ (addr >> 16) ^ (addr >> 24)) & 0xff); +} + +static int count_them(struct ipt_connlimit_data *data, + u_int32_t addr, u_int32_t mask, + struct ip_conntrack *ct) +{ +#if DEBUG + const static char *tcp[] = { "none", "established", "syn_sent", "syn_recv", + "fin_wait", "time_wait", "close", "close_wait", + "last_ack", "listen" }; +#endif + int addit = 1, matches = 0; + struct ip_conntrack_tuple tuple; + struct ip_conntrack_tuple_hash *found; + struct ipt_connlimit_conn *conn; + struct list_head *hash,*lh; + + spin_lock_bh(&data->lock); + tuple = ct->tuplehash[0].tuple; + hash = &data->iphash[ipt_iphash(addr & mask)]; + + /* check the saved connections */ + for (lh = hash->next; lh != hash; lh = lh->next) { + conn = list_entry(lh,struct ipt_connlimit_conn,list); + found = ip_conntrack_find_get(&conn->tuple,ct); + if (found != NULL && + 0 == memcmp(&conn->tuple,&tuple,sizeof(tuple)) && + found->ctrack->proto.tcp.state != TCP_CONNTRACK_TIME_WAIT) { + /* Just to be sure we have it only once in the list. + We should'nt see tuples twice unless someone hooks this + into a table without "-p tcp --syn" */ + addit = 0; + } +#if DEBUG + printk("ipt_connlimit [%d]: src=%u.%u.%u.%u:%d dst=%u.%u.%u.%u:%d %s\n", + ipt_iphash(addr & mask), + NIPQUAD(conn->tuple.src.ip), ntohs(conn->tuple.src.u.tcp.port), + NIPQUAD(conn->tuple.dst.ip), ntohs(conn->tuple.dst.u.tcp.port), + (NULL != found) ? tcp[found->ctrack->proto.tcp.state] : "gone"); +#endif + if (NULL == found) { + /* this one is gone */ + lh = lh->prev; + list_del(lh->next); + kfree(conn); + continue; + } + if (found->ctrack->proto.tcp.state == TCP_CONNTRACK_TIME_WAIT) { + /* we don't care about connections which are + closed already -> ditch it */ + lh = lh->prev; + list_del(lh->next); + kfree(conn); + nf_conntrack_put(&found->ctrack->infos[0]); + continue; + } + if ((addr & mask) == (conn->tuple.src.ip & mask)) { + /* same source IP address -> be counted! */ + matches++; + } + nf_conntrack_put(&found->ctrack->infos[0]); + } + if (addit) { + /* save the new connection in our list */ +#if DEBUG + printk("ipt_connlimit [%d]: src=%u.%u.%u.%u:%d dst=%u.%u.%u.%u:%d new\n", + ipt_iphash(addr & mask), + NIPQUAD(tuple.src.ip), ntohs(tuple.src.u.tcp.port), + NIPQUAD(tuple.dst.ip), ntohs(tuple.dst.u.tcp.port)); +#endif + conn = kmalloc(sizeof(*conn),GFP_ATOMIC); + if (NULL == conn) + return -1; + memset(conn,0,sizeof(*conn)); + INIT_LIST_HEAD(&conn->list); + conn->tuple = tuple; + list_add(&conn->list,hash); + matches++; + } + spin_unlock_bh(&data->lock); + return matches; +} + +static int +match(const struct sk_buff *skb, + const struct net_device *in, + const struct net_device *out, + const void *matchinfo, + int offset, + const void *hdr, + u_int16_t datalen, + int *hotdrop) +{ + const struct ipt_connlimit_info *info = matchinfo; + int connections, match; + struct ip_conntrack *ct; + enum ip_conntrack_info ctinfo; + + ct = ip_conntrack_get((struct sk_buff *)skb, &ctinfo); + if (NULL == ct) { + printk("ipt_connlimit: Oops: invalid ct state ?\n"); + *hotdrop = 1; + return 0; + } + connections = count_them(info->data,skb->nh.iph->saddr,info->mask,ct); + if (-1 == connections) { + printk("ipt_connlimit: Hmm, kmalloc failed :-(\n"); + *hotdrop = 1; /* let's free some memory :-) */ + return 0; + } + match = (info->inverse) ? (connections <= info->limit) : (connections > info->limit); +#if DEBUG + printk("ipt_connlimit: src=%u.%u.%u.%u mask=%u.%u.%u.%u " + "connections=%d limit=%d match=%s\n", + NIPQUAD(skb->nh.iph->saddr), NIPQUAD(info->mask), + connections, info->limit, match ? "yes" : "no"); +#endif + + return match; +} + +static int check(const char *tablename, + const struct ipt_ip *ip, + void *matchinfo, + unsigned int matchsize, + unsigned int hook_mask) +{ + struct ipt_connlimit_info *info = matchinfo; + int i; + + /* verify size */ + if (matchsize != IPT_ALIGN(sizeof(struct ipt_connlimit_info))) + return 0; + + /* refuse anything but tcp */ + if (ip->proto != IPPROTO_TCP) + return 0; + + /* init private data */ + info->data = kmalloc(sizeof(struct ipt_connlimit_data),GFP_KERNEL); + spin_lock_init(&(info->data->lock)); + for (i = 0; i < 256; i++) + INIT_LIST_HEAD(&(info->data->iphash[i])); + + return 1; +} + +static void destroy(void *matchinfo, unsigned int matchinfosize) +{ + struct ipt_connlimit_info *info = matchinfo; + struct ipt_connlimit_conn *conn; + struct list_head *hash; + int i; + + /* cleanup */ + for (i = 0; i < 256; i++) { + hash = &(info->data->iphash[i]); + while (hash != hash->next) { + conn = list_entry(hash->next,struct ipt_connlimit_conn,list); + list_del(hash->next); + kfree(conn); + } + } + kfree(info->data); +} + +static struct ipt_match connlimit_match += { { NULL, NULL }, "connlimit", &match, &check, &destroy, THIS_MODULE }; + +static int __init init(void) +{ + return ipt_register_match(&connlimit_match); +} + +static void __exit fini(void) +{ + ipt_unregister_match(&connlimit_match); +} + +module_init(init); +module_exit(fini); |