/* Kernel module to match AH parameters. *//* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu> * * 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/ipv6.h>#include <linux/types.h>#include <net/checksum.h>#include <net/ipv6.h>#include <linux/netfilter_ipv6/ip6_tables.h>#include <linux/netfilter_ipv6/ip6t_ah.h>MODULE_LICENSE("GPL");MODULE_DESCRIPTION("IPv6 AH match");MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");#if 0#define DEBUGP printk#else#define DEBUGP(format, args...)#endif/* Returns 1 if the spi is matched by the range, 0 otherwise */static inline intspi_match(u_int32_t min, u_int32_t max, u_int32_t spi, int invert){       int r=0;       DEBUGP("ah spi_match:%c 0x%x <= 0x%x <= 0x%x",invert? '!':' ',              min,spi,max);       r=(spi >= min && spi <= max) ^ invert;       DEBUGP(" result %s\n",r? "PASS\n" : "FAILED\n");       return r;}static intmatch(const struct sk_buff *skb,      const struct net_device *in,      const struct net_device *out,      const void *matchinfo,      int offset,      const void *protohdr,      u_int16_t datalen,      int *hotdrop){       struct ip_auth_hdr *ah = NULL;       const struct ip6t_ah *ahinfo = matchinfo;       unsigned int temp;       int len;       u8 nexthdr;       unsigned int ptr;       unsigned int hdrlen = 0;       /*DEBUGP("IPv6 AH entered\n");*/       /* if (opt->auth == 0) return 0;       * It does not filled on output */       /* type of the 1st exthdr */       nexthdr = skb->nh.ipv6h->nexthdr;       /* pointer to the 1st exthdr */       ptr = sizeof(struct ipv6hdr);       /* available length */       len = skb->len - ptr;       temp = 0;        while (ip6t_ext_hdr(nexthdr)) {               struct ipv6_opt_hdr *hdr;              DEBUGP("ipv6_ah header iteration \n");              /* Is there enough space for the next ext header? */                if (len < (int)sizeof(struct ipv6_opt_hdr))                        return 0;              /* No more exthdr -> evaluate */                if (nexthdr == NEXTHDR_NONE) {                     break;              }              /* ESP -> evaluate */                if (nexthdr == NEXTHDR_ESP) {                     break;              }              hdr=(struct ipv6_opt_hdr *)skb->data+ptr;              /* Calculate the header length */                if (nexthdr == NEXTHDR_FRAGMENT) {                        hdrlen = 8;                } else if (nexthdr == NEXTHDR_AUTH)                        hdrlen = (hdr->hdrlen+2)<<2;                else                        hdrlen = ipv6_optlen(hdr);              /* AH -> evaluate */                if (nexthdr == NEXTHDR_AUTH) {                     temp |= MASK_AH;                     break;              }              /* set the flag */              switch (nexthdr){                     case NEXTHDR_HOP:                     case NEXTHDR_ROUTING:                     case NEXTHDR_FRAGMENT:                     case NEXTHDR_AUTH:                     case NEXTHDR_DEST:                            break;                     default:                            DEBUGP("ipv6_ah match: unknown nextheader %u\n",nexthdr);                            return 0;                            break;              }                nexthdr = hdr->nexthdr;                len -= hdrlen;                ptr += hdrlen;		if ( ptr > skb->len ) {			DEBUGP("ipv6_ah: new pointer too large! \n");			break;		}        }       /* AH header not found */       if ( temp != MASK_AH ) return 0;       if (len < (int)sizeof(struct ip_auth_hdr)){	       *hotdrop = 1;       		return 0;       }       ah = (struct ip_auth_hdr *) (skb->data + ptr);       DEBUGP("IPv6 AH LEN %u %u ", hdrlen, ah->hdrlen);       DEBUGP("RES %04X ", ah->reserved);       DEBUGP("SPI %u %08X\n", ntohl(ah->spi), ntohl(ah->spi));       DEBUGP("IPv6 AH spi %02X ",       		(spi_match(ahinfo->spis[0], ahinfo->spis[1],                           ntohl(ah->spi),                           !!(ahinfo->invflags & IP6T_AH_INV_SPI))));       DEBUGP("len %02X %04X %02X ",       		ahinfo->hdrlen, hdrlen,       		(!ahinfo->hdrlen ||                           (ahinfo->hdrlen == hdrlen) ^                           !!(ahinfo->invflags & IP6T_AH_INV_LEN)));       DEBUGP("res %02X %04X %02X\n",        		ahinfo->hdrres, ah->reserved,       		!(ahinfo->hdrres && ah->reserved));       return (ah != NULL)              &&              (spi_match(ahinfo->spis[0], ahinfo->spis[1],                           ntohl(ah->spi),                           !!(ahinfo->invflags & IP6T_AH_INV_SPI)))              &&              (!ahinfo->hdrlen ||                           (ahinfo->hdrlen == hdrlen) ^                           !!(ahinfo->invflags & IP6T_AH_INV_LEN))              &&              !(ahinfo->hdrres && ah->reserved);}/* Called when user tries to insert an entry of this type. */static intcheckentry(const char *tablename,          const struct ip6t_ip6 *ip,          void *matchinfo,          unsigned int matchinfosize,          unsigned int hook_mask){       const struct ip6t_ah *ahinfo = matchinfo;       if (matchinfosize != IP6T_ALIGN(sizeof(struct ip6t_ah))) {              DEBUGP("ip6t_ah: matchsize %u != %u\n",                      matchinfosize, IP6T_ALIGN(sizeof(struct ip6t_ah)));              return 0;       }       if (ahinfo->invflags & ~IP6T_AH_INV_MASK) {              DEBUGP("ip6t_ah: unknown flags %X\n",                      ahinfo->invflags);              return 0;       }       return 1;}static struct ip6t_match ah_match = {	.name		= "ah",	.match		= &match,	.checkentry	= &checkentry,	.me		= THIS_MODULE,};static int __init init(void){       return ip6t_register_match(&ah_match);}static void __exit cleanup(void){       ip6t_unregister_match(&ah_match);}module_init(init);module_exit(cleanup);