| /* 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/x_tables.h> |
| #include <linux/netfilter_ipv6/ip6_tables.h> |
| #include <linux/netfilter_ipv6/ip6t_frag.h> |
| |
| MODULE_LICENSE("GPL"); |
| MODULE_DESCRIPTION("Xtables: IPv6 fragment match"); |
| MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>"); |
| |
| /* Returns 1 if the id is matched by the range, 0 otherwise */ |
| static inline bool |
| id_match(u_int32_t min, u_int32_t max, u_int32_t id, bool invert) |
| { |
| bool r; |
| pr_debug("frag id_match:%c 0x%x <= 0x%x <= 0x%x", invert ? '!' : ' ', |
| min, id, max); |
| r = (id >= min && id <= max) ^ invert; |
| pr_debug(" result %s\n", r ? "PASS" : "FAILED"); |
| return r; |
| } |
| |
| static bool |
| frag_mt6(const struct sk_buff *skb, const struct net_device *in, |
| const struct net_device *out, const struct xt_match *match, |
| const void *matchinfo, int offset, unsigned int protoff, |
| bool *hotdrop) |
| { |
| struct frag_hdr _frag; |
| const struct frag_hdr *fh; |
| const struct ip6t_frag *fraginfo = matchinfo; |
| unsigned int ptr; |
| int err; |
| |
| err = ipv6_find_hdr(skb, &ptr, NEXTHDR_FRAGMENT, NULL); |
| if (err < 0) { |
| if (err != -ENOENT) |
| *hotdrop = true; |
| return false; |
| } |
| |
| fh = skb_header_pointer(skb, ptr, sizeof(_frag), &_frag); |
| if (fh == NULL) { |
| *hotdrop = true; |
| return false; |
| } |
| |
| pr_debug("INFO %04X ", fh->frag_off); |
| pr_debug("OFFSET %04X ", ntohs(fh->frag_off) & ~0x7); |
| pr_debug("RES %02X %04X", fh->reserved, ntohs(fh->frag_off) & 0x6); |
| pr_debug("MF %04X ", fh->frag_off & htons(IP6_MF)); |
| pr_debug("ID %u %08X\n", ntohl(fh->identification), |
| ntohl(fh->identification)); |
| |
| pr_debug("IPv6 FRAG id %02X ", |
| id_match(fraginfo->ids[0], fraginfo->ids[1], |
| ntohl(fh->identification), |
| !!(fraginfo->invflags & IP6T_FRAG_INV_IDS))); |
| pr_debug("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)))); |
| pr_debug("first %02X %02X %02X ", |
| fraginfo->flags & IP6T_FRAG_FST, |
| ntohs(fh->frag_off) & ~0x7, |
| !((fraginfo->flags & IP6T_FRAG_FST) |
| && (ntohs(fh->frag_off) & ~0x7))); |
| pr_debug("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)))); |
| pr_debug("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 bool |
| frag_mt6_check(const char *tablename, const void *ip, |
| const struct xt_match *match, void *matchinfo, |
| unsigned int hook_mask) |
| { |
| const struct ip6t_frag *fraginfo = matchinfo; |
| |
| if (fraginfo->invflags & ~IP6T_FRAG_INV_MASK) { |
| pr_debug("ip6t_frag: unknown flags %X\n", fraginfo->invflags); |
| return false; |
| } |
| return true; |
| } |
| |
| static struct xt_match frag_mt6_reg __read_mostly = { |
| .name = "frag", |
| .family = NFPROTO_IPV6, |
| .match = frag_mt6, |
| .matchsize = sizeof(struct ip6t_frag), |
| .checkentry = frag_mt6_check, |
| .me = THIS_MODULE, |
| }; |
| |
| static int __init frag_mt6_init(void) |
| { |
| return xt_register_match(&frag_mt6_reg); |
| } |
| |
| static void __exit frag_mt6_exit(void) |
| { |
| xt_unregister_match(&frag_mt6_reg); |
| } |
| |
| module_init(frag_mt6_init); |
| module_exit(frag_mt6_exit); |