/* Kernel module to match FRAG parameters. */ /* (C) 2001-2002 Andras Kis-Szabo * * 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 #include #include #include #include MODULE_LICENSE("GPL"); MODULE_DESCRIPTION("IPv6 FRAG match"); MODULE_AUTHOR("Andras Kis-Szabo "); #if 0 #define DEBUGP printk #else #define DEBUGP(format, args...) #endif #if 0 #if BYTE_ORDER == BIG_ENDIAN #define IP6F_OFF_MASK 0xfff8 /* mask out offset from _offlg */ #define IP6F_RESERVED_MASK 0x0006 /* reserved bits in ip6f_offlg */ #define IP6F_MORE_FRAG 0x0001 /* more-fragments flag */ #else /* BYTE_ORDER == LITTLE_ENDIAN */ #define IP6F_OFF_MASK 0xf8ff /* mask out offset from _offlg */ #define IP6F_RESERVED_MASK 0x0600 /* reserved bits in ip6f_offlg */ #define IP6F_MORE_FRAG 0x0100 /* more-fragments flag */ #endif #endif #define IP6F_OFF_MASK 0xf8ff /* mask out offset from _offlg */ #define IP6F_RESERVED_MASK 0x0600 /* reserved bits in ip6f_offlg */ #define IP6F_MORE_FRAG 0x0100 /* more-fragments flag */ struct fraghdr { __u8 nexthdr; __u8 hdrlen; __u16 info; __u32 id; }; /* 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, const void *protohdr, u_int16_t datalen, int *hotdrop) { struct fraghdr *frag = 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; 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; } 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); /* 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 = hdr->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 < (int)sizeof(struct fraghdr)){ *hotdrop = 1; return 0; } frag = (struct fraghdr *) (skb->data + ptr); DEBUGP("IPv6 FRAG LEN %u %u ", hdrlen, frag->hdrlen); DEBUGP("INFO %04X ", frag->info); DEBUGP("OFFSET %04X ", frag->info & IP6F_OFF_MASK); DEBUGP("RES %04X ", frag->info & IP6F_RESERVED_MASK); DEBUGP("MF %04X ", frag->info & IP6F_MORE_FRAG); DEBUGP("ID %u %08X\n", ntohl(frag->id), ntohl(frag->id)); DEBUGP("IPv6 FRAG id %02X ", (id_match(fraginfo->ids[0], fraginfo->ids[1], ntohl(frag->id), !!(fraginfo->invflags & IP6T_FRAG_INV_IDS)))); DEBUGP("len %02X %04X %02X ", fraginfo->hdrlen, hdrlen, (!fraginfo->hdrlen || (fraginfo->hdrlen == hdrlen) ^ !!(fraginfo->invflags & IP6T_FRAG_INV_LEN))); DEBUGP("res %02X %02X %02X ", (fraginfo->flags & IP6T_FRAG_RES), frag->info & IP6F_RESERVED_MASK, !((fraginfo->flags & IP6T_FRAG_RES) && (frag->info & IP6F_RESERVED_MASK))); DEBUGP("first %02X %02X %02X ", (fraginfo->flags & IP6T_FRAG_FST), frag->info & IP6F_OFF_MASK, !((fraginfo->flags & IP6T_FRAG_FST) && (frag->info & IP6F_OFF_MASK))); DEBUGP("mf %02X %02X %02X ", (fraginfo->flags & IP6T_FRAG_MF), frag->info & IP6F_MORE_FRAG, !((fraginfo->flags & IP6T_FRAG_MF) && !((frag->info & IP6F_MORE_FRAG)))); DEBUGP("last %02X %02X %02X\n", (fraginfo->flags & IP6T_FRAG_NMF), frag->info & IP6F_MORE_FRAG, !((fraginfo->flags & IP6T_FRAG_NMF) && (frag->info & IP6F_MORE_FRAG))); return (frag != NULL) && (id_match(fraginfo->ids[0], fraginfo->ids[1], ntohl(frag->id), !!(fraginfo->invflags & IP6T_FRAG_INV_IDS))) && (!fraginfo->hdrlen || (fraginfo->hdrlen == hdrlen) ^ !!(fraginfo->invflags & IP6T_FRAG_INV_LEN)) && !((fraginfo->flags & IP6T_FRAG_RES) && (frag->info & IP6F_RESERVED_MASK)) && !((fraginfo->flags & IP6T_FRAG_FST) && (frag->info & IP6F_OFF_MASK)) && !((fraginfo->flags & IP6T_FRAG_MF) && !((frag->info & IP6F_MORE_FRAG))) && !((fraginfo->flags & IP6T_FRAG_NMF) && (frag->info & IP6F_MORE_FRAG)); } /* 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);