diff options
Diffstat (limited to 'net/ipv4/netfilter/ipt_esp.c')
-rw-r--r-- | net/ipv4/netfilter/ipt_esp.c | 118 |
1 files changed, 118 insertions, 0 deletions
diff --git a/net/ipv4/netfilter/ipt_esp.c b/net/ipv4/netfilter/ipt_esp.c new file mode 100644 index 000000000000..e1d0dd31e117 --- /dev/null +++ b/net/ipv4/netfilter/ipt_esp.c @@ -0,0 +1,118 @@ +/* Kernel module to match ESP parameters. */ + +/* (C) 1999-2000 Yon Uriarte <yon@astaro.de> + * + * 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/skbuff.h> +#include <linux/ip.h> + +#include <linux/netfilter_ipv4/ipt_esp.h> +#include <linux/netfilter_ipv4/ip_tables.h> + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Yon Uriarte <yon@astaro.de>"); +MODULE_DESCRIPTION("iptables ESP SPI match module"); + +#ifdef DEBUG_CONNTRACK +#define duprintf(format, args...) printk(format , ## args) +#else +#define duprintf(format, args...) +#endif + +/* Returns 1 if the spi is matched by the range, 0 otherwise */ +static inline int +spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, int invert) +{ + int r=0; + duprintf("esp spi_match:%c 0x%x <= 0x%x <= 0x%x",invert? '!':' ', + min,spi,max); + r=(spi >= min && spi <= max) ^ invert; + duprintf(" result %s\n",r? "PASS" : "FAILED"); + return r; +} + +static int +match(const struct sk_buff *skb, + const struct net_device *in, + const struct net_device *out, + const void *matchinfo, + int offset, + int *hotdrop) +{ + struct ip_esp_hdr _esp, *eh; + const struct ipt_esp *espinfo = matchinfo; + + /* Must not be a fragment. */ + if (offset) + return 0; + + eh = skb_header_pointer(skb, skb->nh.iph->ihl * 4, + sizeof(_esp), &_esp); + if (eh == NULL) { + /* We've been asked to examine this packet, and we + * can't. Hence, no choice but to drop. + */ + duprintf("Dropping evil ESP tinygram.\n"); + *hotdrop = 1; + return 0; + } + + return spi_match(espinfo->spis[0], espinfo->spis[1], + ntohl(eh->spi), + !!(espinfo->invflags & IPT_ESP_INV_SPI)); +} + +/* Called when user tries to insert an entry of this type. */ +static int +checkentry(const char *tablename, + const struct ipt_ip *ip, + void *matchinfo, + unsigned int matchinfosize, + unsigned int hook_mask) +{ + const struct ipt_esp *espinfo = matchinfo; + + /* Must specify proto == ESP, and no unknown invflags */ + if (ip->proto != IPPROTO_ESP || (ip->invflags & IPT_INV_PROTO)) { + duprintf("ipt_esp: Protocol %u != %u\n", ip->proto, + IPPROTO_ESP); + return 0; + } + if (matchinfosize != IPT_ALIGN(sizeof(struct ipt_esp))) { + duprintf("ipt_esp: matchsize %u != %u\n", + matchinfosize, IPT_ALIGN(sizeof(struct ipt_esp))); + return 0; + } + if (espinfo->invflags & ~IPT_ESP_INV_MASK) { + duprintf("ipt_esp: unknown flags %X\n", + espinfo->invflags); + return 0; + } + + return 1; +} + +static struct ipt_match esp_match = { + .name = "esp", + .match = &match, + .checkentry = &checkentry, + .me = THIS_MODULE, +}; + +static int __init init(void) +{ + return ipt_register_match(&esp_match); +} + +static void __exit cleanup(void) +{ + ipt_unregister_match(&esp_match); +} + +module_init(init); +module_exit(cleanup); |