| /* Kernel module to match FRAG 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_frag.h> |
| |
| MODULE_LICENSE("GPL"); |
| MODULE_DESCRIPTION("IPv6 FRAG 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 id is matched by the range, 0 otherwise */ |
| static inline int |
| id_match(u_int32_t min, u_int32_t max, u_int32_t id, int invert) |
| { |
| int r=0; |
| DEBUGP("frag id_match:%c 0x%x <= 0x%x <= 0x%x",invert? '!':' ', |
| min,id,max); |
| r=(id >= min && id <= max) ^ invert; |
| DEBUGP(" 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, |
| unsigned int protoff, |
| int *hotdrop) |
| { |
| struct frag_hdr _frag, *fh = NULL; |
| const struct ip6t_frag *fraginfo = matchinfo; |
| unsigned int temp; |
| int len; |
| u8 nexthdr; |
| unsigned int ptr; |
| unsigned int hdrlen = 0; |
| |
| /* 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, *hp; |
| |
| DEBUGP("ipv6_frag 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; |
| } |
| |
| hp = skb_header_pointer(skb, ptr, sizeof(_hdr), &_hdr); |
| BUG_ON(hp == NULL); |
| |
| /* Calculate the header length */ |
| if (nexthdr == NEXTHDR_FRAGMENT) { |
| hdrlen = 8; |
| } else if (nexthdr == NEXTHDR_AUTH) |
| hdrlen = (hp->hdrlen+2)<<2; |
| else |
| hdrlen = ipv6_optlen(hp); |
| |
| /* FRAG -> evaluate */ |
| if (nexthdr == NEXTHDR_FRAGMENT) { |
| temp |= MASK_FRAGMENT; |
| 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_frag match: unknown nextheader %u\n",nexthdr); |
| return 0; |
| break; |
| } |
| |
| nexthdr = hp->nexthdr; |
| len -= hdrlen; |
| ptr += hdrlen; |
| if ( ptr > skb->len ) { |
| DEBUGP("ipv6_frag: new pointer too large! \n"); |
| break; |
| } |
| } |
| |
| /* FRAG header not found */ |
| if ( temp != MASK_FRAGMENT ) return 0; |
| |
| if (len < sizeof(struct frag_hdr)){ |
| *hotdrop = 1; |
| return 0; |
| } |
| |
| fh = skb_header_pointer(skb, ptr, sizeof(_frag), &_frag); |
| BUG_ON(fh == NULL); |
| |
| DEBUGP("INFO %04X ", fh->frag_off); |
| DEBUGP("OFFSET %04X ", ntohs(fh->frag_off) & ~0x7); |
| DEBUGP("RES %02X %04X", fh->reserved, ntohs(fh->frag_off) & 0x6); |
| DEBUGP("MF %04X ", fh->frag_off & htons(IP6_MF)); |
| DEBUGP("ID %u %08X\n", ntohl(fh->identification), |
| ntohl(fh->identification)); |
| |
| DEBUGP("IPv6 FRAG id %02X ", |
| (id_match(fraginfo->ids[0], fraginfo->ids[1], |
| ntohl(fh->identification), |
| !!(fraginfo->invflags & IP6T_FRAG_INV_IDS)))); |
| DEBUGP("res %02X %02X%04X %02X ", |
| (fraginfo->flags & IP6T_FRAG_RES), fh->reserved, |
| ntohs(fh->frag_off) & 0x6, |
| !((fraginfo->flags & IP6T_FRAG_RES) |
| && (fh->reserved || (ntohs(fh->frag_off) & 0x06)))); |
| DEBUGP("first %02X %02X %02X ", |
| (fraginfo->flags & IP6T_FRAG_FST), |
| ntohs(fh->frag_off) & ~0x7, |
| !((fraginfo->flags & IP6T_FRAG_FST) |
| && (ntohs(fh->frag_off) & ~0x7))); |
| DEBUGP("mf %02X %02X %02X ", |
| (fraginfo->flags & IP6T_FRAG_MF), |
| ntohs(fh->frag_off) & IP6_MF, |
| !((fraginfo->flags & IP6T_FRAG_MF) |
| && !((ntohs(fh->frag_off) & IP6_MF)))); |
| DEBUGP("last %02X %02X %02X\n", |
| (fraginfo->flags & IP6T_FRAG_NMF), |
| ntohs(fh->frag_off) & IP6_MF, |
| !((fraginfo->flags & IP6T_FRAG_NMF) |
| && (ntohs(fh->frag_off) & IP6_MF))); |
| |
| return (fh != NULL) |
| && |
| (id_match(fraginfo->ids[0], fraginfo->ids[1], |
| ntohl(fh->identification), |
| !!(fraginfo->invflags & IP6T_FRAG_INV_IDS))) |
| && |
| !((fraginfo->flags & IP6T_FRAG_RES) |
| && (fh->reserved || (ntohs(fh->frag_off) & 0x6))) |
| && |
| !((fraginfo->flags & IP6T_FRAG_FST) |
| && (ntohs(fh->frag_off) & ~0x7)) |
| && |
| !((fraginfo->flags & IP6T_FRAG_MF) |
| && !(ntohs(fh->frag_off) & IP6_MF)) |
| && |
| !((fraginfo->flags & IP6T_FRAG_NMF) |
| && (ntohs(fh->frag_off) & IP6_MF)); |
| } |
| |
| /* Called when user tries to insert an entry of this type. */ |
| static int |
| checkentry(const char *tablename, |
| const struct ip6t_ip6 *ip, |
| void *matchinfo, |
| unsigned int matchinfosize, |
| unsigned int hook_mask) |
| { |
| const struct ip6t_frag *fraginfo = matchinfo; |
| |
| if (matchinfosize != IP6T_ALIGN(sizeof(struct ip6t_frag))) { |
| DEBUGP("ip6t_frag: matchsize %u != %u\n", |
| matchinfosize, IP6T_ALIGN(sizeof(struct ip6t_frag))); |
| return 0; |
| } |
| if (fraginfo->invflags & ~IP6T_FRAG_INV_MASK) { |
| DEBUGP("ip6t_frag: unknown flags %X\n", |
| fraginfo->invflags); |
| return 0; |
| } |
| |
| return 1; |
| } |
| |
| static struct ip6t_match frag_match = { |
| .name = "frag", |
| .match = &match, |
| .checkentry = &checkentry, |
| .me = THIS_MODULE, |
| }; |
| |
| static int __init init(void) |
| { |
| return ip6t_register_match(&frag_match); |
| } |
| |
| static void __exit cleanup(void) |
| { |
| ip6t_unregister_match(&frag_match); |
| } |
| |
| module_init(init); |
| module_exit(cleanup); |