diff options
Diffstat (limited to 'net/ipv4/netfilter/ipt_SAME.c')
| -rw-r--r-- | net/ipv4/netfilter/ipt_SAME.c | 211 |
1 files changed, 211 insertions, 0 deletions
diff --git a/net/ipv4/netfilter/ipt_SAME.c b/net/ipv4/netfilter/ipt_SAME.c new file mode 100644 index 00000000000..7a0536d864a --- /dev/null +++ b/net/ipv4/netfilter/ipt_SAME.c @@ -0,0 +1,211 @@ +/* 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> +#include <linux/netfilter_ipv4/ip_nat_rule.h> +#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 struct ipt_entry *e, + void *targinfo, + unsigned int targinfosize, + unsigned int hook_mask) +{ + unsigned int count, countess, rangeip, index = 0; + struct ipt_same_info *mr = targinfo; + + mr->ipnum = 0; + + if (strcmp(tablename, "nat") != 0) { + DEBUGP("same_check: bad table `%s'.\n", tablename); + return 0; + } + if (targinfosize != IPT_ALIGN(sizeof(*mr))) { + DEBUGP("same_check: size %u.\n", targinfosize); + return 0; + } + if (hook_mask & ~(1 << NF_IP_PRE_ROUTING | 1 << NF_IP_POST_ROUTING)) { + DEBUGP("same_check: bad hooks %x.\n", hook_mask); + return 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(void *targinfo, + unsigned int targinfosize) +{ + 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 void *targinfo, + void *userinfo) +{ + struct ip_conntrack *ct; + enum ip_conntrack_info ctinfo; + u_int32_t tmpip, aindex, 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 */ + + tmpip = ntohl(t->src.ip); + + if (!(same->info & IPT_SAME_NODST)) + tmpip += ntohl(t->dst.ip); + + 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, + .checkentry = same_check, + .destroy = same_destroy, + .me = THIS_MODULE, +}; + +static int __init init(void) +{ + return ipt_register_target(&same_reg); +} + +static void __exit fini(void) +{ + ipt_unregister_target(&same_reg); +} + +module_init(init); +module_exit(fini); + |