From 764d8a9f240729534a1d8a0ffd39e722cf5cc5af Mon Sep 17 00:00:00 2001 From: Patrick McHardy Date: Sun, 21 Aug 2005 23:31:06 -0700 Subject: [NETFILTER]: Add IPv6 REJECT target Originally written by Yasuyuki Kozakai , taken from netfilter patch-o-matic and fixed up to work with current kernels. Signed-off-by: Patrick McHardy Signed-off-by: David S. Miller --- net/ipv6/netfilter/Kconfig | 10 ++ net/ipv6/netfilter/Makefile | 1 + net/ipv6/netfilter/ip6t_REJECT.c | 284 +++++++++++++++++++++++++++++++++++++++ 3 files changed, 295 insertions(+) create mode 100644 net/ipv6/netfilter/ip6t_REJECT.c (limited to 'net') diff --git a/net/ipv6/netfilter/Kconfig b/net/ipv6/netfilter/Kconfig index cd1551983c63..8a10c2d0d154 100644 --- a/net/ipv6/netfilter/Kconfig +++ b/net/ipv6/netfilter/Kconfig @@ -199,6 +199,16 @@ config IP6_NF_TARGET_LOG To compile it as a module, choose M here. If unsure, say N. +config IP6_NF_TARGET_REJECT + tristate "REJECT target support" + depends on IP6_NF_FILTER + help + The REJECT target allows a filtering rule to specify that an ICMPv6 + error should be issued in response to an incoming packet, rather + than silently being dropped. + + To compile it as a module, choose M here. If unsure, say N. + # if [ "$CONFIG_IP6_NF_FILTER" != "n" ]; then # dep_tristate ' REJECT target support' CONFIG_IP6_NF_TARGET_REJECT $CONFIG_IP6_NF_FILTER # if [ "$CONFIG_EXPERIMENTAL" = "y" ]; then diff --git a/net/ipv6/netfilter/Makefile b/net/ipv6/netfilter/Makefile index 847651dbcd2a..70f6ba610102 100644 --- a/net/ipv6/netfilter/Makefile +++ b/net/ipv6/netfilter/Makefile @@ -24,4 +24,5 @@ obj-$(CONFIG_IP6_NF_QUEUE) += ip6_queue.o obj-$(CONFIG_IP6_NF_TARGET_LOG) += ip6t_LOG.o obj-$(CONFIG_IP6_NF_RAW) += ip6table_raw.o obj-$(CONFIG_IP6_NF_MATCH_HL) += ip6t_hl.o +obj-$(CONFIG_IP6_NF_TARGET_REJECT) += ip6t_REJECT.o obj-$(CONFIG_NETFILTER_NETLINK_QUEUE) += ip6t_NFQUEUE.o diff --git a/net/ipv6/netfilter/ip6t_REJECT.c b/net/ipv6/netfilter/ip6t_REJECT.c new file mode 100644 index 000000000000..14316c3ebde4 --- /dev/null +++ b/net/ipv6/netfilter/ip6t_REJECT.c @@ -0,0 +1,284 @@ +/* + * IP6 tables REJECT target module + * Linux INET6 implementation + * + * Copyright (C)2003 USAGI/WIDE Project + * + * Authors: + * Yasuyuki Kozakai + * + * Based on net/ipv4/netfilter/ipt_REJECT.c + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +MODULE_AUTHOR("Yasuyuki KOZAKAI "); +MODULE_DESCRIPTION("IP6 tables REJECT target module"); +MODULE_LICENSE("GPL"); + +#if 0 +#define DEBUGP printk +#else +#define DEBUGP(format, args...) +#endif + +/* Send RST reply */ +static void send_reset(struct sk_buff *oldskb) +{ + struct sk_buff *nskb; + struct tcphdr otcph, *tcph; + unsigned int otcplen, hh_len; + int tcphoff, needs_ack; + struct ipv6hdr *oip6h = oldskb->nh.ipv6h, *ip6h; + struct dst_entry *dst = NULL; + u8 proto; + struct flowi fl; + + if ((!(ipv6_addr_type(&oip6h->saddr) & IPV6_ADDR_UNICAST)) || + (!(ipv6_addr_type(&oip6h->daddr) & IPV6_ADDR_UNICAST))) { + DEBUGP("ip6t_REJECT: addr is not unicast.\n"); + return; + } + + proto = oip6h->nexthdr; + tcphoff = ipv6_skip_exthdr(oldskb, ((u8*)(oip6h+1) - oldskb->data), &proto); + + if ((tcphoff < 0) || (tcphoff > oldskb->len)) { + DEBUGP("ip6t_REJECT: Can't get TCP header.\n"); + return; + } + + otcplen = oldskb->len - tcphoff; + + /* IP header checks: fragment, too short. */ + if ((proto != IPPROTO_TCP) || (otcplen < sizeof(struct tcphdr))) { + DEBUGP("ip6t_REJECT: proto(%d) != IPPROTO_TCP, or too short. otcplen = %d\n", + proto, otcplen); + return; + } + + if (skb_copy_bits(oldskb, tcphoff, &otcph, sizeof(struct tcphdr))) + BUG(); + + /* No RST for RST. */ + if (otcph.rst) { + DEBUGP("ip6t_REJECT: RST is set\n"); + return; + } + + /* Check checksum. */ + if (csum_ipv6_magic(&oip6h->saddr, &oip6h->daddr, otcplen, IPPROTO_TCP, + skb_checksum(oldskb, tcphoff, otcplen, 0))) { + DEBUGP("ip6t_REJECT: TCP checksum is invalid\n"); + return; + } + + memset(&fl, 0, sizeof(fl)); + fl.proto = IPPROTO_TCP; + ipv6_addr_copy(&fl.fl6_src, &oip6h->daddr); + ipv6_addr_copy(&fl.fl6_dst, &oip6h->saddr); + fl.fl_ip_sport = otcph.dest; + fl.fl_ip_dport = otcph.source; + dst = ip6_route_output(NULL, &fl); + if (dst == NULL) + return; + if (dst->error || + xfrm_lookup(&dst, &fl, NULL, 0)) { + dst_release(dst); + return; + } + + hh_len = (dst->dev->hard_header_len + 15)&~15; + nskb = alloc_skb(hh_len + 15 + dst->header_len + sizeof(struct ipv6hdr) + + sizeof(struct tcphdr) + dst->trailer_len, + GFP_ATOMIC); + + if (!nskb) { + if (net_ratelimit()) + printk("ip6t_REJECT: Can't alloc skb\n"); + dst_release(dst); + return; + } + + nskb->dst = dst; + + skb_reserve(nskb, hh_len + dst->header_len); + + ip6h = nskb->nh.ipv6h = (struct ipv6hdr *) + skb_put(nskb, sizeof(struct ipv6hdr)); + ip6h->version = 6; + ip6h->hop_limit = dst_metric(dst, RTAX_HOPLIMIT); + ip6h->nexthdr = IPPROTO_TCP; + ip6h->payload_len = htons(sizeof(struct tcphdr)); + ipv6_addr_copy(&ip6h->saddr, &oip6h->daddr); + ipv6_addr_copy(&ip6h->daddr, &oip6h->saddr); + + tcph = (struct tcphdr *)skb_put(nskb, sizeof(struct tcphdr)); + /* Truncate to length (no data) */ + tcph->doff = sizeof(struct tcphdr)/4; + tcph->source = otcph.dest; + tcph->dest = otcph.source; + + if (otcph.ack) { + needs_ack = 0; + tcph->seq = otcph.ack_seq; + tcph->ack_seq = 0; + } else { + needs_ack = 1; + tcph->ack_seq = htonl(ntohl(otcph.seq) + otcph.syn + otcph.fin + + otcplen - (otcph.doff<<2)); + tcph->seq = 0; + } + + /* Reset flags */ + ((u_int8_t *)tcph)[13] = 0; + tcph->rst = 1; + tcph->ack = needs_ack; + tcph->window = 0; + tcph->urg_ptr = 0; + tcph->check = 0; + + /* Adjust TCP checksum */ + tcph->check = csum_ipv6_magic(&nskb->nh.ipv6h->saddr, + &nskb->nh.ipv6h->daddr, + sizeof(struct tcphdr), IPPROTO_TCP, + csum_partial((char *)tcph, + sizeof(struct tcphdr), 0)); + + NF_HOOK(PF_INET6, NF_IP6_LOCAL_OUT, nskb, NULL, nskb->dst->dev, + dst_output); +} + +static inline void +send_unreach(struct sk_buff *skb_in, unsigned char code, unsigned int hooknum) +{ + if (hooknum == NF_IP6_LOCAL_OUT && skb_in->dev == NULL) + skb_in->dev = &loopback_dev; + + icmpv6_send(skb_in, ICMPV6_DEST_UNREACH, code, 0, NULL); +} + +static unsigned int reject6_target(struct sk_buff **pskb, + const struct net_device *in, + const struct net_device *out, + unsigned int hooknum, + const void *targinfo, + void *userinfo) +{ + const struct ip6t_reject_info *reject = targinfo; + + DEBUGP(KERN_DEBUG "%s: medium point\n", __FUNCTION__); + /* WARNING: This code causes reentry within ip6tables. + This means that the ip6tables jump stack is now crap. We + must return an absolute verdict. --RR */ + switch (reject->with) { + case IP6T_ICMP6_NO_ROUTE: + send_unreach(*pskb, ICMPV6_NOROUTE, hooknum); + break; + case IP6T_ICMP6_ADM_PROHIBITED: + send_unreach(*pskb, ICMPV6_ADM_PROHIBITED, hooknum); + break; + case IP6T_ICMP6_NOT_NEIGHBOUR: + send_unreach(*pskb, ICMPV6_NOT_NEIGHBOUR, hooknum); + break; + case IP6T_ICMP6_ADDR_UNREACH: + send_unreach(*pskb, ICMPV6_ADDR_UNREACH, hooknum); + break; + case IP6T_ICMP6_PORT_UNREACH: + send_unreach(*pskb, ICMPV6_PORT_UNREACH, hooknum); + break; + case IP6T_ICMP6_ECHOREPLY: + /* Do nothing */ + break; + case IP6T_TCP_RESET: + send_reset(*pskb); + break; + default: + if (net_ratelimit()) + printk(KERN_WARNING "ip6t_REJECT: case %u not handled yet\n", reject->with); + break; + } + + return NF_DROP; +} + +static int check(const char *tablename, + const struct ip6t_entry *e, + void *targinfo, + unsigned int targinfosize, + unsigned int hook_mask) +{ + const struct ip6t_reject_info *rejinfo = targinfo; + + if (targinfosize != IP6T_ALIGN(sizeof(struct ip6t_reject_info))) { + DEBUGP("ip6t_REJECT: targinfosize %u != 0\n", targinfosize); + return 0; + } + + /* Only allow these for packet filtering. */ + if (strcmp(tablename, "filter") != 0) { + DEBUGP("ip6t_REJECT: bad table `%s'.\n", tablename); + return 0; + } + + if ((hook_mask & ~((1 << NF_IP6_LOCAL_IN) + | (1 << NF_IP6_FORWARD) + | (1 << NF_IP6_LOCAL_OUT))) != 0) { + DEBUGP("ip6t_REJECT: bad hook mask %X\n", hook_mask); + return 0; + } + + if (rejinfo->with == IP6T_ICMP6_ECHOREPLY) { + printk("ip6t_REJECT: ECHOREPLY is not supported.\n"); + return 0; + } else if (rejinfo->with == IP6T_TCP_RESET) { + /* Must specify that it's a TCP packet */ + if (e->ipv6.proto != IPPROTO_TCP + || (e->ipv6.invflags & IP6T_INV_PROTO)) { + DEBUGP("ip6t_REJECT: TCP_RESET illegal for non-tcp\n"); + return 0; + } + } + + return 1; +} + +static struct ip6t_target ip6t_reject_reg = { + .name = "REJECT", + .target = reject6_target, + .checkentry = check, + .me = THIS_MODULE +}; + +static int __init init(void) +{ + if (ip6t_register_target(&ip6t_reject_reg)) + return -EINVAL; + return 0; +} + +static void __exit fini(void) +{ + ip6t_unregister_target(&ip6t_reject_reg); +} + +module_init(init); +module_exit(fini); -- cgit v1.2.3-59-g8ed1b