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![Jan Engelhardt](/assets/img/avatar_default.png)
Use the x_tables functions directly to make it better visible which parts are shared between ip_tables and ip6_tables. Signed-off-by: Jan Engelhardt <jengelh@gmx.de> Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
159 lines
4.3 KiB
C
159 lines
4.3 KiB
C
/* Kernel module to match FRAG parameters. */
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/* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <linux/ipv6.h>
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#include <linux/types.h>
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#include <net/checksum.h>
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#include <net/ipv6.h>
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#include <linux/netfilter/x_tables.h>
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#include <linux/netfilter_ipv6/ip6_tables.h>
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#include <linux/netfilter_ipv6/ip6t_frag.h>
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("IPv6 FRAG match");
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MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
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#if 0
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#define DEBUGP printk
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#else
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#define DEBUGP(format, args...)
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#endif
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/* Returns 1 if the id is matched by the range, 0 otherwise */
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static inline int
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id_match(u_int32_t min, u_int32_t max, u_int32_t id, int invert)
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{
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int r = 0;
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DEBUGP("frag id_match:%c 0x%x <= 0x%x <= 0x%x", invert ? '!' : ' ',
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min, id, max);
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r = (id >= min && id <= max) ^ invert;
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DEBUGP(" result %s\n", r ? "PASS" : "FAILED");
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return r;
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}
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static int
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match(const struct sk_buff *skb,
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const struct net_device *in,
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const struct net_device *out,
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const struct xt_match *match,
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const void *matchinfo,
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int offset,
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unsigned int protoff,
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int *hotdrop)
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{
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struct frag_hdr _frag, *fh;
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const struct ip6t_frag *fraginfo = matchinfo;
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unsigned int ptr;
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int err;
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err = ipv6_find_hdr(skb, &ptr, NEXTHDR_FRAGMENT, NULL);
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if (err < 0) {
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if (err != -ENOENT)
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*hotdrop = 1;
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return 0;
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}
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fh = skb_header_pointer(skb, ptr, sizeof(_frag), &_frag);
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if (fh == NULL) {
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*hotdrop = 1;
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return 0;
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}
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DEBUGP("INFO %04X ", fh->frag_off);
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DEBUGP("OFFSET %04X ", ntohs(fh->frag_off) & ~0x7);
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DEBUGP("RES %02X %04X", fh->reserved, ntohs(fh->frag_off) & 0x6);
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DEBUGP("MF %04X ", fh->frag_off & htons(IP6_MF));
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DEBUGP("ID %u %08X\n", ntohl(fh->identification),
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ntohl(fh->identification));
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DEBUGP("IPv6 FRAG id %02X ",
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(id_match(fraginfo->ids[0], fraginfo->ids[1],
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ntohl(fh->identification),
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!!(fraginfo->invflags & IP6T_FRAG_INV_IDS))));
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DEBUGP("res %02X %02X%04X %02X ",
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(fraginfo->flags & IP6T_FRAG_RES), fh->reserved,
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ntohs(fh->frag_off) & 0x6,
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!((fraginfo->flags & IP6T_FRAG_RES)
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&& (fh->reserved || (ntohs(fh->frag_off) & 0x06))));
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DEBUGP("first %02X %02X %02X ",
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(fraginfo->flags & IP6T_FRAG_FST),
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ntohs(fh->frag_off) & ~0x7,
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!((fraginfo->flags & IP6T_FRAG_FST)
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&& (ntohs(fh->frag_off) & ~0x7)));
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DEBUGP("mf %02X %02X %02X ",
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(fraginfo->flags & IP6T_FRAG_MF),
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ntohs(fh->frag_off) & IP6_MF,
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!((fraginfo->flags & IP6T_FRAG_MF)
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&& !((ntohs(fh->frag_off) & IP6_MF))));
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DEBUGP("last %02X %02X %02X\n",
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(fraginfo->flags & IP6T_FRAG_NMF),
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ntohs(fh->frag_off) & IP6_MF,
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!((fraginfo->flags & IP6T_FRAG_NMF)
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&& (ntohs(fh->frag_off) & IP6_MF)));
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return (fh != NULL)
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&&
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(id_match(fraginfo->ids[0], fraginfo->ids[1],
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ntohl(fh->identification),
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!!(fraginfo->invflags & IP6T_FRAG_INV_IDS)))
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&&
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!((fraginfo->flags & IP6T_FRAG_RES)
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&& (fh->reserved || (ntohs(fh->frag_off) & 0x6)))
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&&
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!((fraginfo->flags & IP6T_FRAG_FST)
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&& (ntohs(fh->frag_off) & ~0x7))
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&&
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!((fraginfo->flags & IP6T_FRAG_MF)
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&& !(ntohs(fh->frag_off) & IP6_MF))
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&&
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!((fraginfo->flags & IP6T_FRAG_NMF)
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&& (ntohs(fh->frag_off) & IP6_MF));
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}
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/* Called when user tries to insert an entry of this type. */
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static int
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checkentry(const char *tablename,
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const void *ip,
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const struct xt_match *match,
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void *matchinfo,
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unsigned int hook_mask)
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{
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const struct ip6t_frag *fraginfo = matchinfo;
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if (fraginfo->invflags & ~IP6T_FRAG_INV_MASK) {
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DEBUGP("ip6t_frag: unknown flags %X\n", fraginfo->invflags);
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return 0;
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}
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return 1;
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}
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static struct xt_match frag_match = {
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.name = "frag",
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.family = AF_INET6,
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.match = match,
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.matchsize = sizeof(struct ip6t_frag),
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.checkentry = checkentry,
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.me = THIS_MODULE,
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};
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static int __init ip6t_frag_init(void)
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{
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return xt_register_match(&frag_match);
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}
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static void __exit ip6t_frag_fini(void)
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{
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xt_unregister_match(&frag_match);
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}
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module_init(ip6t_frag_init);
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module_exit(ip6t_frag_fini);
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