From 2e4e6a17af35be359cc8f1c924f8f198fbd478cc Mon Sep 17 00:00:00 2001 From: Harald Welte Date: Thu, 12 Jan 2006 13:30:04 -0800 Subject: [NETFILTER] x_tables: Abstraction layer for {ip,ip6,arp}_tables This monster-patch tries to do the best job for unifying the data structures and backend interfaces for the three evil clones ip_tables, ip6_tables and arp_tables. In an ideal world we would never have allowed this kind of copy+paste programming... but well, our world isn't (yet?) ideal. o introduce a new x_tables module o {ip,arp,ip6}_tables depend on this x_tables module o registration functions for tables, matches and targets are only wrappers around x_tables provided functions o all matches/targets that are used from ip_tables and ip6_tables are now implemented as xt_FOOBAR.c files and provide module aliases to ipt_FOOBAR and ip6t_FOOBAR o header files for xt_matches are in include/linux/netfilter/, include/linux/netfilter_{ipv4,ipv6} contains compatibility wrappers around the xt_FOOBAR.h headers Based on this patchset we're going to further unify the code, gradually getting rid of all the layer 3 specific assumptions. Signed-off-by: Harald Welte Signed-off-by: David S. Miller --- net/netfilter/xt_length.c | 98 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 98 insertions(+) create mode 100644 net/netfilter/xt_length.c (limited to 'net/netfilter/xt_length.c') diff --git a/net/netfilter/xt_length.c b/net/netfilter/xt_length.c new file mode 100644 index 00000000000..ab6c710cf88 --- /dev/null +++ b/net/netfilter/xt_length.c @@ -0,0 +1,98 @@ +/* Kernel module to match packet length. */ +/* (C) 1999-2001 James Morris + * + * 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 +#include +#include + +#include +#include + +MODULE_AUTHOR("James Morris "); +MODULE_DESCRIPTION("IP tables packet length matching module"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("ipt_length"); +MODULE_ALIAS("ip6t_length"); + +static int +match(const struct sk_buff *skb, + const struct net_device *in, + const struct net_device *out, + const void *matchinfo, + int offset, + unsigned int protoff, + int *hotdrop) +{ + const struct xt_length_info *info = matchinfo; + u_int16_t pktlen = ntohs(skb->nh.iph->tot_len); + + return (pktlen >= info->min && pktlen <= info->max) ^ info->invert; +} + +static int +match6(const struct sk_buff *skb, + const struct net_device *in, + const struct net_device *out, + const void *matchinfo, + int offset, + unsigned int protoff, + int *hotdrop) +{ + const struct xt_length_info *info = matchinfo; + u_int16_t pktlen = ntohs(skb->nh.ipv6h->payload_len) + sizeof(struct ipv6hdr); + + return (pktlen >= info->min && pktlen <= info->max) ^ info->invert; +} + +static int +checkentry(const char *tablename, + const void *ip, + void *matchinfo, + unsigned int matchsize, + unsigned int hook_mask) +{ + if (matchsize != XT_ALIGN(sizeof(struct xt_length_info))) + return 0; + + return 1; +} + +static struct xt_match length_match = { + .name = "length", + .match = &match, + .checkentry = &checkentry, + .me = THIS_MODULE, +}; +static struct xt_match length6_match = { + .name = "length", + .match = &match6, + .checkentry = &checkentry, + .me = THIS_MODULE, +}; + +static int __init init(void) +{ + int ret; + ret = xt_register_match(AF_INET, &length_match); + if (ret) + return ret; + ret = xt_register_match(AF_INET6, &length6_match); + if (ret) + xt_unregister_match(AF_INET, &length_match); + + return ret; +} + +static void __exit fini(void) +{ + xt_unregister_match(AF_INET, &length_match); + xt_unregister_match(AF_INET6, &length6_match); +} + +module_init(init); +module_exit(fini); -- cgit v1.2.3