ipt_clusterip.c

h内核

/* Cluster IP hashmark target 
 * (C) 2003-2004 by Harald Welte <[e-mail]>
 * based on ideas of Fabio Olive Leite <[e-mail]>
 *
 * Development of this code funded by SuSE Linux AG, http://www.suse.com/
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */
#include <linux/module.h>
#include <linux/config.h>
#include <linux/proc_fs.h>
#include <linux/jhash.h>
#include <linux/skbuff.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <linux/icmp.h>
#include <linux/if_arp.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>

#include <net/checksum.h>

#include <linux/netfilter_arp.h>

#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv4/ipt_CLUSTERIP.h>
#include <linux/netfilter_ipv4/ip_conntrack.h>
#include <linux/netfilter_ipv4/lockhelp.h>

#define CLUSTERIP_VERSION "0.6"

#define DEBUG_CLUSTERIP

#ifdef DEBUG_CLUSTERIP
#define DEBUGP	printk
#else
#define DEBUGP
#endif

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Harald Welte <[e-mail]>");
MODULE_DESCRIPTION("iptables target for CLUSTERIP");

struct clusterip_config {
	struct list_head list;			/* list of all configs */
	atomic_t refcount;			/* reference count */

	u_int32_t clusterip;			/* the IP address */
	u_int8_t clustermac[ETH_ALEN];		/* the MAC address */
	struct net_device *dev;			/* device */
	u_int16_t num_total_nodes;		/* total number of nodes */
	u_int16_t num_local_nodes;		/* number of local nodes */
	u_int16_t local_nodes[CLUSTERIP_MAX_NODES];	/* node number array */

#ifdef CONFIG_PROC_FS
	struct proc_dir_entry *pde;		/* proc dir entry */
#endif
	enum clusterip_hashmode hash_mode;	/* which hashing mode */
	u_int32_t hash_initval;			/* hash initialization */
};

static LIST_HEAD(clusterip_configs);

/* clusterip_lock protects the clusterip_configs list _AND_ the configurable
 * data within all structurses (num_local_nodes, local_nodes[]) */
static DECLARE_RWLOCK(clusterip_lock);

#ifdef CONFIG_PROC_FS
static struct file_operations clusterip_proc_fops;
static struct proc_dir_entry *clusterip_procdir;
#endif

static inline void
clusterip_config_get(struct clusterip_config *c) {
	atomic_inc(&c->refcount);
}

static inline void
clusterip_config_put(struct clusterip_config *c) {
	if (atomic_dec_and_test(&c->refcount)) {
		WRITE_LOCK(&clusterip_lock);
		list_del(&c->list);
		WRITE_UNLOCK(&clusterip_lock);
		dev_mc_delete(c->dev, c->clustermac, ETH_ALEN, 0);
		dev_put(c->dev);
		kfree(c);
	}
}


static struct clusterip_config *
__clusterip_config_find(u_int32_t clusterip)
{
	struct list_head *pos;

	MUST_BE_READ_LOCKED(&clusterip_lock);
	list_for_each(pos, &clusterip_configs) {
		struct clusterip_config *c = list_entry(pos, 
					struct clusterip_config, list);
		if (c->clusterip == clusterip) {
			return c;
		}
	}

	return NULL;
}

static inline struct clusterip_config *
clusterip_config_find_get(u_int32_t clusterip)
{
	struct clusterip_config *c;

	READ_LOCK(&clusterip_lock);
	c = __clusterip_config_find(clusterip);
	if (!c) {
		READ_UNLOCK(&clusterip_lock);
		return NULL;
	}
	atomic_inc(&c->refcount);
	READ_UNLOCK(&clusterip_lock);

	return c;
}

static struct clusterip_config *
clusterip_config_init(struct ipt_clusterip_tgt_info *i, u_int32_t ip,
			struct net_device *dev)
{
	struct clusterip_config *c;
	char buffer[16];

	c = kmalloc(sizeof(*c), GFP_ATOMIC);
	if (!c)
		return NULL;

	memset(c, 0, sizeof(*c));
	c->dev = dev;
	c->clusterip = ip;
	memcpy(&c->clustermac, &i->clustermac, ETH_ALEN);
	c->num_total_nodes = i->num_total_nodes;
	c->num_local_nodes = i->num_local_nodes;
	memcpy(&c->local_nodes, &i->local_nodes, sizeof(&c->local_nodes));
	c->hash_mode = i->hash_mode;
	c->hash_initval = i->hash_initval;
	atomic_set(&c->refcount, 1);

#ifdef CONFIG_PROC_FS
	/* create proc dir entry */
	sprintf(buffer, "%u.%u.%u.%u", NIPQUAD(ip));
	c->pde = create_proc_entry(buffer, S_IWUSR|S_IRUSR, clusterip_procdir);
	if (!c->pde) {
		kfree(c);
		return NULL;
	}
	c->pde->proc_fops = &clusterip_proc_fops;
	c->pde->data = c;
#endif

	WRITE_LOCK(&clusterip_lock);
	list_add(&c->list, &clusterip_configs);
	WRITE_UNLOCK(&clusterip_lock);

	return c;
}

static int
clusterip_add_node(struct clusterip_config *c, u_int16_t nodenum)
{
	int i;

	WRITE_LOCK(&clusterip_lock);

	if (c->num_local_nodes >= CLUSTERIP_MAX_NODES
	    || nodenum > CLUSTERIP_MAX_NODES) {
		WRITE_UNLOCK(&clusterip_lock);
		return 1;
	}

	/* check if we alrady have this number in our array */
	for (i = 0; i < c->num_local_nodes; i++) {
		if (c->local_nodes[i] == nodenum) {
			WRITE_UNLOCK(&clusterip_lock);
			return 1;
		}
	}

	c->local_nodes[c->num_local_nodes++] = nodenum;

	WRITE_UNLOCK(&clusterip_lock);
	return 0;
}

static int
clusterip_del_node(struct clusterip_config *c, u_int16_t nodenum)
{
	int i;

	WRITE_LOCK(&clusterip_lock);

	if (c->num_local_nodes <= 1 || nodenum > CLUSTERIP_MAX_NODES) {
		WRITE_UNLOCK(&clusterip_lock);
		return 1;
	}
		
	for (i = 0; i < c->num_local_nodes; i++) {
		if (c->local_nodes[i] == nodenum) {
			int size = sizeof(u_int16_t)*(c->num_local_nodes-(i+1));
			memmove(&c->local_nodes[i], &c->local_nodes[i+1], size);
			c->num_local_nodes--;
			WRITE_UNLOCK(&clusterip_lock);
			return 0;
		}
	}

	WRITE_UNLOCK(&clusterip_lock);
	return 1;
}

static inline u_int32_t
clusterip_hashfn(struct sk_buff *skb, struct clusterip_config *config)
{
	struct iphdr *iph = skb->nh.iph;
	unsigned long hashval;
	u_int16_t sport, dport;
	struct tcphdr *th;
	struct udphdr *uh;
	struct icmphdr *ih;

	switch (iph->protocol) {
	case IPPROTO_TCP:
		th = (void *)iph+iph->ihl*4;
		sport = ntohs(th->source);
		dport = ntohs(th->dest);
		break;
	case IPPROTO_UDP:
		uh = (void *)iph+iph->ihl*4;
		sport = ntohs(uh->source);
		dport = ntohs(uh->dest);
		break;
	case IPPROTO_ICMP:
		ih = (void *)iph+iph->ihl*4;
		sport = ntohs(ih->un.echo.id);
		dport = (ih->type<<8)|ih->code;
		break;
	default:
		if (net_ratelimit()) {
			printk(KERN_NOTICE "CLUSTERIP: unknown protocol `%u'\n",
				iph->protocol);
		}
		sport = dport = 0;
	}

	switch (config->hash_mode) {
	case CLUSTERIP_HASHMODE_SIP:
		hashval = jhash_1word(ntohl(iph->saddr),
				      config->hash_initval);
		break;
	case CLUSTERIP_HASHMODE_SIP_SPT:
		hashval = jhash_2words(ntohl(iph->saddr), sport, 
				       config->hash_initval);
		break;
	case CLUSTERIP_HASHMODE_SIP_SPT_DPT:
		hashval = jhash_3words(ntohl(iph->saddr), sport, dport,
				       config->hash_initval);
		break;
	default:
		/* to make gcc happy */
		hashval = 0;
		/* This cannot happen, unless the check function wasn't called
		 * at rule load time */
		printk("CLUSTERIP: unknown mode `%u'\n", config->hash_mode);
		BUG();
		break;
	}

	/* node numbers are 1..n, not 0..n */
	return ((hashval % config->num_total_nodes)+1);
}

static inline int
clusterip_responsible(struct clusterip_config *config, u_int32_t hash)
{
	int i;

	READ_LOCK(&clusterip_lock);

	if (config->num_local_nodes == 0) {
		READ_UNLOCK(&clusterip_lock);
		return 0;
	}

	for (i = 0; i < config->num_local_nodes; i++) {
		if (config->local_nodes[i] == hash) {
			READ_UNLOCK(&clusterip_lock);
			return 1;
		}
	}

	READ_UNLOCK(&clusterip_lock);

	return 0;
}

/*********************************************************************** 
 * IPTABLES TARGET 
 ***********************************************************************/

static unsigned int
target(struct sk_buff **pskb,
       const struct net_device *in,
       const struct net_device *out,
       unsigned int hooknum,
       const void *targinfo,
       void *userinfo)
{
	const struct ipt_clusterip_tgt_info *cipinfo = targinfo;
	enum ip_conntrack_info ctinfo;
	struct ip_conntrack *ct = ip_conntrack_get((*pskb), &ctinfo);
	u_int32_t hash;

	/* don't need to clusterip_config_get() here, since refcount
	 * is only decremented by destroy() - and ip_tables guarantees
	 * that the ->target() function isn't called after ->destroy() */

	if (!ct) {
		printk(KERN_ERR "CLUSTERIP: no conntrack!\n");
			/* FIXME: need to drop invalid ones, since replies
			 * to outgoing connections of other nodes will be 
			 * marked as INVALID */
		return NF_DROP;
	}

	/* special case: ICMP error handling. conntrack distinguishes between
	 * error messages (RELATED) and information requests (see below) */
	if ((*pskb)->nh.iph->protocol == IPPROTO_ICMP
	    && (ctinfo == IP_CT_RELATED 
		|| ctinfo == IP_CT_IS_REPLY+IP_CT_IS_REPLY))
		return IPT_CONTINUE;

	/* ip_conntrack_icmp guarantees us that we only have ICMP_ECHO, 
	 * TIMESTAMP, INFO_REQUEST or ADDRESS type icmp packets from here
	 * on, which all have an ID field [relevant for hashing]. */

	hash = clusterip_hashfn(*pskb, cipinfo->config);

	switch (ctinfo) {
		case IP_CT_NEW:
			ct->mark = hash;
			break;
		case IP_CT_RELATED:
		case IP_CT_RELATED+IP_CT_IS_REPLY:
			/* FIXME: we don't handle expectations at the
			 * moment.  they can arrive on a different node than
			 * the master connection (e.g. FTP passive mode) */
		case IP_CT_ESTABLISHED:
		case IP_CT_ESTABLISHED+IP_CT_IS_REPLY:
			break;
		default:
			break;
	}

#ifdef DEBUG_CLUSTERP
	DUMP_TUPLE(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
#endif
	DEBUGP("hash=%u ct_hash=%lu ", hash, ct->mark);
	if (!clusterip_responsible(cipinfo->config, hash)) {
		DEBUGP("not responsible\n");
		return NF_DROP;
	}
	DEBUGP("responsible\n");

	/* despite being received via linklayer multicast, this is
	 * actually a unicast IP packet. TCP doesn't like PACKET_MULTICAST */
	(*pskb)->pkt_type = PACKET_HOST;

	return IPT_CONTINUE;
}