| /* Same. Just like SNAT, only try to make the connections |
| * between client A and server B always have the same source ip. |
| * |
| * (C) 2000 Paul `Rusty' Russell |
| * (C) 2001 Martin Josefsson |
| * |
| * 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. |
| * |
| * 010320 Martin Josefsson <gandalf@wlug.westbo.se> |
| * * copied ipt_BALANCE.c to ipt_SAME.c and changed a few things. |
| * 010728 Martin Josefsson <gandalf@wlug.westbo.se> |
| * * added --nodst to not include destination-ip in new source |
| * calculations. |
| * * added some more sanity-checks. |
| * 010729 Martin Josefsson <gandalf@wlug.westbo.se> |
| * * fixed a buggy if-statement in same_check(), should have |
| * used ntohl() but didn't. |
| * * added support for multiple ranges. IPT_SAME_MAX_RANGE is |
| * defined in linux/include/linux/netfilter_ipv4/ipt_SAME.h |
| * and is currently set to 10. |
| * * added support for 1-address range, nice to have now that |
| * we have multiple ranges. |
| */ |
| #include <linux/types.h> |
| #include <linux/ip.h> |
| #include <linux/timer.h> |
| #include <linux/module.h> |
| #include <linux/netfilter.h> |
| #include <linux/netdevice.h> |
| #include <linux/if.h> |
| #include <linux/inetdevice.h> |
| #include <net/protocol.h> |
| #include <net/checksum.h> |
| #include <linux/netfilter_ipv4.h> |
| #ifdef CONFIG_NF_NAT_NEEDED |
| #include <net/netfilter/nf_nat_rule.h> |
| #else |
| #include <linux/netfilter_ipv4/ip_nat_rule.h> |
| #endif |
| #include <linux/netfilter_ipv4/ipt_SAME.h> |
| |
| MODULE_LICENSE("GPL"); |
| MODULE_AUTHOR("Martin Josefsson <gandalf@wlug.westbo.se>"); |
| MODULE_DESCRIPTION("iptables special SNAT module for consistent sourceip"); |
| |
| #if 0 |
| #define DEBUGP printk |
| #else |
| #define DEBUGP(format, args...) |
| #endif |
| |
| static int |
| same_check(const char *tablename, |
| const void *e, |
| const struct xt_target *target, |
| void *targinfo, |
| unsigned int hook_mask) |
| { |
| unsigned int count, countess, rangeip, index = 0; |
| struct ipt_same_info *mr = targinfo; |
| |
| mr->ipnum = 0; |
| |
| if (mr->rangesize < 1) { |
| DEBUGP("same_check: need at least one dest range.\n"); |
| return 0; |
| } |
| if (mr->rangesize > IPT_SAME_MAX_RANGE) { |
| DEBUGP("same_check: too many ranges specified, maximum " |
| "is %u ranges\n", |
| IPT_SAME_MAX_RANGE); |
| return 0; |
| } |
| for (count = 0; count < mr->rangesize; count++) { |
| if (ntohl(mr->range[count].min_ip) > |
| ntohl(mr->range[count].max_ip)) { |
| DEBUGP("same_check: min_ip is larger than max_ip in " |
| "range `%u.%u.%u.%u-%u.%u.%u.%u'.\n", |
| NIPQUAD(mr->range[count].min_ip), |
| NIPQUAD(mr->range[count].max_ip)); |
| return 0; |
| } |
| if (!(mr->range[count].flags & IP_NAT_RANGE_MAP_IPS)) { |
| DEBUGP("same_check: bad MAP_IPS.\n"); |
| return 0; |
| } |
| rangeip = (ntohl(mr->range[count].max_ip) - |
| ntohl(mr->range[count].min_ip) + 1); |
| mr->ipnum += rangeip; |
| |
| DEBUGP("same_check: range %u, ipnum = %u\n", count, rangeip); |
| } |
| DEBUGP("same_check: total ipaddresses = %u\n", mr->ipnum); |
| |
| mr->iparray = kmalloc((sizeof(u_int32_t) * mr->ipnum), GFP_KERNEL); |
| if (!mr->iparray) { |
| DEBUGP("same_check: Couldn't allocate %u bytes " |
| "for %u ipaddresses!\n", |
| (sizeof(u_int32_t) * mr->ipnum), mr->ipnum); |
| return 0; |
| } |
| DEBUGP("same_check: Allocated %u bytes for %u ipaddresses.\n", |
| (sizeof(u_int32_t) * mr->ipnum), mr->ipnum); |
| |
| for (count = 0; count < mr->rangesize; count++) { |
| for (countess = ntohl(mr->range[count].min_ip); |
| countess <= ntohl(mr->range[count].max_ip); |
| countess++) { |
| mr->iparray[index] = countess; |
| DEBUGP("same_check: Added ipaddress `%u.%u.%u.%u' " |
| "in index %u.\n", |
| HIPQUAD(countess), index); |
| index++; |
| } |
| } |
| return 1; |
| } |
| |
| static void |
| same_destroy(const struct xt_target *target, void *targinfo) |
| { |
| struct ipt_same_info *mr = targinfo; |
| |
| kfree(mr->iparray); |
| |
| DEBUGP("same_destroy: Deallocated %u bytes for %u ipaddresses.\n", |
| (sizeof(u_int32_t) * mr->ipnum), mr->ipnum); |
| } |
| |
| static unsigned int |
| same_target(struct sk_buff **pskb, |
| const struct net_device *in, |
| const struct net_device *out, |
| unsigned int hooknum, |
| const struct xt_target *target, |
| const void *targinfo) |
| { |
| struct ip_conntrack *ct; |
| enum ip_conntrack_info ctinfo; |
| u_int32_t tmpip, aindex; |
| __be32 new_ip; |
| const struct ipt_same_info *same = targinfo; |
| struct ip_nat_range newrange; |
| const struct ip_conntrack_tuple *t; |
| |
| IP_NF_ASSERT(hooknum == NF_IP_PRE_ROUTING || |
| hooknum == NF_IP_POST_ROUTING); |
| ct = ip_conntrack_get(*pskb, &ctinfo); |
| |
| t = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple; |
| |
| /* Base new source on real src ip and optionally dst ip, |
| giving some hope for consistency across reboots. |
| Here we calculate the index in same->iparray which |
| holds the ipaddress we should use */ |
| |
| #ifdef CONFIG_NF_NAT_NEEDED |
| tmpip = ntohl(t->src.u3.ip); |
| |
| if (!(same->info & IPT_SAME_NODST)) |
| tmpip += ntohl(t->dst.u3.ip); |
| #else |
| tmpip = ntohl(t->src.ip); |
| |
| if (!(same->info & IPT_SAME_NODST)) |
| tmpip += ntohl(t->dst.ip); |
| #endif |
| aindex = tmpip % same->ipnum; |
| |
| new_ip = htonl(same->iparray[aindex]); |
| |
| DEBUGP("ipt_SAME: src=%u.%u.%u.%u dst=%u.%u.%u.%u, " |
| "new src=%u.%u.%u.%u\n", |
| NIPQUAD(t->src.ip), NIPQUAD(t->dst.ip), |
| NIPQUAD(new_ip)); |
| |
| /* Transfer from original range. */ |
| newrange = ((struct ip_nat_range) |
| { same->range[0].flags, new_ip, new_ip, |
| /* FIXME: Use ports from correct range! */ |
| same->range[0].min, same->range[0].max }); |
| |
| /* Hand modified range to generic setup. */ |
| return ip_nat_setup_info(ct, &newrange, hooknum); |
| } |
| |
| static struct ipt_target same_reg = { |
| .name = "SAME", |
| .target = same_target, |
| .targetsize = sizeof(struct ipt_same_info), |
| .table = "nat", |
| .hooks = (1 << NF_IP_PRE_ROUTING | 1 << NF_IP_POST_ROUTING), |
| .checkentry = same_check, |
| .destroy = same_destroy, |
| .me = THIS_MODULE, |
| }; |
| |
| static int __init ipt_same_init(void) |
| { |
| return ipt_register_target(&same_reg); |
| } |
| |
| static void __exit ipt_same_fini(void) |
| { |
| ipt_unregister_target(&same_reg); |
| } |
| |
| module_init(ipt_same_init); |
| module_exit(ipt_same_fini); |
| |