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- /* (C) 1999-2001 Paul `Rusty' Russell
- * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
- *
- * 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.
- *
- * 16 Dec 2003: Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
- * - enable working with Layer 3 protocol independent connection tracking.
- *
- * Derived from net/ipv4/netfilter/ip_conntrack_proto_icmp.c
- */
- #include <linux/types.h>
- #include <linux/timer.h>
- #include <linux/netfilter.h>
- #include <linux/in.h>
- #include <linux/icmp.h>
- #include <linux/seq_file.h>
- #include <net/ip.h>
- #include <net/checksum.h>
- #include <linux/netfilter_ipv4.h>
- #include <net/netfilter/nf_conntrack_tuple.h>
- #include <net/netfilter/nf_conntrack_l4proto.h>
- #include <net/netfilter/nf_conntrack_core.h>
- static unsigned long nf_ct_icmp_timeout __read_mostly = 30*HZ;
- #if 0
- #define DEBUGP printk
- #else
- #define DEBUGP(format, args...)
- #endif
- static int icmp_pkt_to_tuple(const struct sk_buff *skb,
- unsigned int dataoff,
- struct nf_conntrack_tuple *tuple)
- {
- struct icmphdr _hdr, *hp;
- hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
- if (hp == NULL)
- return 0;
- tuple->dst.u.icmp.type = hp->type;
- tuple->src.u.icmp.id = hp->un.echo.id;
- tuple->dst.u.icmp.code = hp->code;
- return 1;
- }
- /* Add 1; spaces filled with 0. */
- static const u_int8_t invmap[] = {
- [ICMP_ECHO] = ICMP_ECHOREPLY + 1,
- [ICMP_ECHOREPLY] = ICMP_ECHO + 1,
- [ICMP_TIMESTAMP] = ICMP_TIMESTAMPREPLY + 1,
- [ICMP_TIMESTAMPREPLY] = ICMP_TIMESTAMP + 1,
- [ICMP_INFO_REQUEST] = ICMP_INFO_REPLY + 1,
- [ICMP_INFO_REPLY] = ICMP_INFO_REQUEST + 1,
- [ICMP_ADDRESS] = ICMP_ADDRESSREPLY + 1,
- [ICMP_ADDRESSREPLY] = ICMP_ADDRESS + 1
- };
- static int icmp_invert_tuple(struct nf_conntrack_tuple *tuple,
- const struct nf_conntrack_tuple *orig)
- {
- if (orig->dst.u.icmp.type >= sizeof(invmap)
- || !invmap[orig->dst.u.icmp.type])
- return 0;
- tuple->src.u.icmp.id = orig->src.u.icmp.id;
- tuple->dst.u.icmp.type = invmap[orig->dst.u.icmp.type] - 1;
- tuple->dst.u.icmp.code = orig->dst.u.icmp.code;
- return 1;
- }
- /* Print out the per-protocol part of the tuple. */
- static int icmp_print_tuple(struct seq_file *s,
- const struct nf_conntrack_tuple *tuple)
- {
- return seq_printf(s, "type=%u code=%u id=%u ",
- tuple->dst.u.icmp.type,
- tuple->dst.u.icmp.code,
- ntohs(tuple->src.u.icmp.id));
- }
- /* Print out the private part of the conntrack. */
- static int icmp_print_conntrack(struct seq_file *s,
- const struct nf_conn *conntrack)
- {
- return 0;
- }
- /* Returns verdict for packet, or -1 for invalid. */
- static int icmp_packet(struct nf_conn *ct,
- const struct sk_buff *skb,
- unsigned int dataoff,
- enum ip_conntrack_info ctinfo,
- int pf,
- unsigned int hooknum)
- {
- /* Try to delete connection immediately after all replies:
- won't actually vanish as we still have skb, and del_timer
- means this will only run once even if count hits zero twice
- (theoretically possible with SMP) */
- if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
- if (atomic_dec_and_test(&ct->proto.icmp.count)
- && del_timer(&ct->timeout))
- ct->timeout.function((unsigned long)ct);
- } else {
- atomic_inc(&ct->proto.icmp.count);
- nf_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, skb);
- nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_icmp_timeout);
- }
- return NF_ACCEPT;
- }
- /* Called when a new connection for this protocol found. */
- static int icmp_new(struct nf_conn *conntrack,
- const struct sk_buff *skb, unsigned int dataoff)
- {
- static const u_int8_t valid_new[] = {
- [ICMP_ECHO] = 1,
- [ICMP_TIMESTAMP] = 1,
- [ICMP_INFO_REQUEST] = 1,
- [ICMP_ADDRESS] = 1
- };
- if (conntrack->tuplehash[0].tuple.dst.u.icmp.type >= sizeof(valid_new)
- || !valid_new[conntrack->tuplehash[0].tuple.dst.u.icmp.type]) {
- /* Can't create a new ICMP `conn' with this. */
- DEBUGP("icmp: can't create new conn with type %u\n",
- conntrack->tuplehash[0].tuple.dst.u.icmp.type);
- NF_CT_DUMP_TUPLE(&conntrack->tuplehash[0].tuple);
- return 0;
- }
- atomic_set(&conntrack->proto.icmp.count, 0);
- return 1;
- }
- extern struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv4;
- /* Returns conntrack if it dealt with ICMP, and filled in skb fields */
- static int
- icmp_error_message(struct sk_buff *skb,
- enum ip_conntrack_info *ctinfo,
- unsigned int hooknum)
- {
- struct nf_conntrack_tuple innertuple, origtuple;
- struct {
- struct icmphdr icmp;
- struct iphdr ip;
- } _in, *inside;
- struct nf_conntrack_l4proto *innerproto;
- struct nf_conntrack_tuple_hash *h;
- int dataoff;
- NF_CT_ASSERT(skb->nfct == NULL);
- /* Not enough header? */
- inside = skb_header_pointer(skb, skb->nh.iph->ihl*4, sizeof(_in), &_in);
- if (inside == NULL)
- return -NF_ACCEPT;
- /* Ignore ICMP's containing fragments (shouldn't happen) */
- if (inside->ip.frag_off & htons(IP_OFFSET)) {
- DEBUGP("icmp_error_message: fragment of proto %u\n",
- inside->ip.protocol);
- return -NF_ACCEPT;
- }
- /* rcu_read_lock()ed by nf_hook_slow */
- innerproto = __nf_ct_l4proto_find(PF_INET, inside->ip.protocol);
- dataoff = skb->nh.iph->ihl*4 + sizeof(inside->icmp);
- /* Are they talking about one of our connections? */
- if (!nf_ct_get_tuple(skb, dataoff, dataoff + inside->ip.ihl*4, PF_INET,
- inside->ip.protocol, &origtuple,
- &nf_conntrack_l3proto_ipv4, innerproto)) {
- DEBUGP("icmp_error_message: ! get_tuple p=%u",
- inside->ip.protocol);
- return -NF_ACCEPT;
- }
- /* Ordinarily, we'd expect the inverted tupleproto, but it's
- been preserved inside the ICMP. */
- if (!nf_ct_invert_tuple(&innertuple, &origtuple,
- &nf_conntrack_l3proto_ipv4, innerproto)) {
- DEBUGP("icmp_error_message: no match\n");
- return -NF_ACCEPT;
- }
- *ctinfo = IP_CT_RELATED;
- h = nf_conntrack_find_get(&innertuple, NULL);
- if (!h) {
- /* Locally generated ICMPs will match inverted if they
- haven't been SNAT'ed yet */
- /* FIXME: NAT code has to handle half-done double NAT --RR */
- if (hooknum == NF_IP_LOCAL_OUT)
- h = nf_conntrack_find_get(&origtuple, NULL);
- if (!h) {
- DEBUGP("icmp_error_message: no match\n");
- return -NF_ACCEPT;
- }
- /* Reverse direction from that found */
- if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
- *ctinfo += IP_CT_IS_REPLY;
- } else {
- if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
- *ctinfo += IP_CT_IS_REPLY;
- }
- /* Update skb to refer to this connection */
- skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general;
- skb->nfctinfo = *ctinfo;
- return -NF_ACCEPT;
- }
- /* Small and modified version of icmp_rcv */
- static int
- icmp_error(struct sk_buff *skb, unsigned int dataoff,
- enum ip_conntrack_info *ctinfo, int pf, unsigned int hooknum)
- {
- struct icmphdr _ih, *icmph;
- /* Not enough header? */
- icmph = skb_header_pointer(skb, skb->nh.iph->ihl*4, sizeof(_ih), &_ih);
- if (icmph == NULL) {
- if (LOG_INVALID(IPPROTO_ICMP))
- nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
- "nf_ct_icmp: short packet ");
- return -NF_ACCEPT;
- }
- /* See ip_conntrack_proto_tcp.c */
- if (nf_conntrack_checksum && hooknum == NF_IP_PRE_ROUTING &&
- nf_ip_checksum(skb, hooknum, dataoff, 0)) {
- if (LOG_INVALID(IPPROTO_ICMP))
- nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
- "nf_ct_icmp: bad HW ICMP checksum ");
- return -NF_ACCEPT;
- }
- /*
- * 18 is the highest 'known' ICMP type. Anything else is a mystery
- *
- * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
- * discarded.
- */
- if (icmph->type > NR_ICMP_TYPES) {
- if (LOG_INVALID(IPPROTO_ICMP))
- nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
- "nf_ct_icmp: invalid ICMP type ");
- return -NF_ACCEPT;
- }
- /* Need to track icmp error message? */
- if (icmph->type != ICMP_DEST_UNREACH
- && icmph->type != ICMP_SOURCE_QUENCH
- && icmph->type != ICMP_TIME_EXCEEDED
- && icmph->type != ICMP_PARAMETERPROB
- && icmph->type != ICMP_REDIRECT)
- return NF_ACCEPT;
- return icmp_error_message(skb, ctinfo, hooknum);
- }
- #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
- #include <linux/netfilter/nfnetlink.h>
- #include <linux/netfilter/nfnetlink_conntrack.h>
- static int icmp_tuple_to_nfattr(struct sk_buff *skb,
- const struct nf_conntrack_tuple *t)
- {
- NFA_PUT(skb, CTA_PROTO_ICMP_ID, sizeof(u_int16_t),
- &t->src.u.icmp.id);
- NFA_PUT(skb, CTA_PROTO_ICMP_TYPE, sizeof(u_int8_t),
- &t->dst.u.icmp.type);
- NFA_PUT(skb, CTA_PROTO_ICMP_CODE, sizeof(u_int8_t),
- &t->dst.u.icmp.code);
- return 0;
- nfattr_failure:
- return -1;
- }
- static const size_t cta_min_proto[CTA_PROTO_MAX] = {
- [CTA_PROTO_ICMP_TYPE-1] = sizeof(u_int8_t),
- [CTA_PROTO_ICMP_CODE-1] = sizeof(u_int8_t),
- [CTA_PROTO_ICMP_ID-1] = sizeof(u_int16_t)
- };
- static int icmp_nfattr_to_tuple(struct nfattr *tb[],
- struct nf_conntrack_tuple *tuple)
- {
- if (!tb[CTA_PROTO_ICMP_TYPE-1]
- || !tb[CTA_PROTO_ICMP_CODE-1]
- || !tb[CTA_PROTO_ICMP_ID-1])
- return -EINVAL;
- if (nfattr_bad_size(tb, CTA_PROTO_MAX, cta_min_proto))
- return -EINVAL;
- tuple->dst.u.icmp.type =
- *(u_int8_t *)NFA_DATA(tb[CTA_PROTO_ICMP_TYPE-1]);
- tuple->dst.u.icmp.code =
- *(u_int8_t *)NFA_DATA(tb[CTA_PROTO_ICMP_CODE-1]);
- tuple->src.u.icmp.id =
- *(__be16 *)NFA_DATA(tb[CTA_PROTO_ICMP_ID-1]);
- if (tuple->dst.u.icmp.type >= sizeof(invmap)
- || !invmap[tuple->dst.u.icmp.type])
- return -EINVAL;
- return 0;
- }
- #endif
- #ifdef CONFIG_SYSCTL
- static struct ctl_table_header *icmp_sysctl_header;
- static struct ctl_table icmp_sysctl_table[] = {
- {
- .ctl_name = NET_NF_CONNTRACK_ICMP_TIMEOUT,
- .procname = "nf_conntrack_icmp_timeout",
- .data = &nf_ct_icmp_timeout,
- .maxlen = sizeof(unsigned int),
- .mode = 0644,
- .proc_handler = &proc_dointvec_jiffies,
- },
- {
- .ctl_name = 0
- }
- };
- #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
- static struct ctl_table icmp_compat_sysctl_table[] = {
- {
- .ctl_name = NET_IPV4_NF_CONNTRACK_ICMP_TIMEOUT,
- .procname = "ip_conntrack_icmp_timeout",
- .data = &nf_ct_icmp_timeout,
- .maxlen = sizeof(unsigned int),
- .mode = 0644,
- .proc_handler = &proc_dointvec_jiffies,
- },
- {
- .ctl_name = 0
- }
- };
- #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
- #endif /* CONFIG_SYSCTL */
- struct nf_conntrack_l4proto nf_conntrack_l4proto_icmp =
- {
- .l3proto = PF_INET,
- .l4proto = IPPROTO_ICMP,
- .name = "icmp",
- .pkt_to_tuple = icmp_pkt_to_tuple,
- .invert_tuple = icmp_invert_tuple,
- .print_tuple = icmp_print_tuple,
- .print_conntrack = icmp_print_conntrack,
- .packet = icmp_packet,
- .new = icmp_new,
- .error = icmp_error,
- .destroy = NULL,
- .me = NULL,
- #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
- .tuple_to_nfattr = icmp_tuple_to_nfattr,
- .nfattr_to_tuple = icmp_nfattr_to_tuple,
- #endif
- #ifdef CONFIG_SYSCTL
- .ctl_table_header = &icmp_sysctl_header,
- .ctl_table = icmp_sysctl_table,
- #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
- .ctl_compat_table = icmp_compat_sysctl_table,
- #endif
- #endif
- };
- EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_icmp);
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