/Linux/net/ipv4/netfilter/nf_conntrack_proto_icmp.c
C | 324 lines | 251 code | 41 blank | 32 comment | 43 complexity | d72d69c1c52288780d4c110b2d1b365a MD5 | raw file
- /* (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.
- */
- #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>
- #include <net/netfilter/nf_log.h>
- static unsigned long nf_ct_icmp_timeout __read_mostly = 30*HZ;
- static int icmp_pkt_to_tuple(const struct sk_buff *skb,
- unsigned int dataoff,
- struct nf_conntrack_tuple *tuple)
- {
- const struct icmphdr *hp;
- struct icmphdr _hdr;
- 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));
- }
- /* 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 *ct,
- 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 (ct->tuplehash[0].tuple.dst.u.icmp.type >= sizeof(valid_new)
- || !valid_new[ct->tuplehash[0].tuple.dst.u.icmp.type]) {
- /* Can't create a new ICMP `conn' with this. */
- pr_debug("icmp: can't create new conn with type %u\n",
- ct->tuplehash[0].tuple.dst.u.icmp.type);
- NF_CT_DUMP_TUPLE(&ct->tuplehash[0].tuple);
- return 0;
- }
- atomic_set(&ct->proto.icmp.count, 0);
- return 1;
- }
- /* 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;
- const struct nf_conntrack_l4proto *innerproto;
- const struct nf_conntrack_tuple_hash *h;
- NF_CT_ASSERT(skb->nfct == NULL);
- /* Are they talking about one of our connections? */
- if (!nf_ct_get_tuplepr(skb,
- skb_network_offset(skb) + ip_hdrlen(skb)
- + sizeof(struct icmphdr),
- PF_INET, &origtuple)) {
- pr_debug("icmp_error_message: failed to get tuple\n");
- return -NF_ACCEPT;
- }
- /* rcu_read_lock()ed by nf_hook_slow */
- innerproto = __nf_ct_l4proto_find(PF_INET, origtuple.dst.protonum);
- /* 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)) {
- pr_debug("icmp_error_message: no match\n");
- return -NF_ACCEPT;
- }
- *ctinfo = IP_CT_RELATED;
- h = nf_conntrack_find_get(&innertuple);
- if (!h) {
- pr_debug("icmp_error_message: no match\n");
- return -NF_ACCEPT;
- }
- 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)
- {
- const struct icmphdr *icmph;
- struct icmphdr _ih;
- /* Not enough header? */
- icmph = skb_header_pointer(skb, ip_hdrlen(skb), 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_INET_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_nlattr(struct sk_buff *skb,
- const struct nf_conntrack_tuple *t)
- {
- NLA_PUT_BE16(skb, CTA_PROTO_ICMP_ID, t->src.u.icmp.id);
- NLA_PUT_U8(skb, CTA_PROTO_ICMP_TYPE, t->dst.u.icmp.type);
- NLA_PUT_U8(skb, CTA_PROTO_ICMP_CODE, t->dst.u.icmp.code);
- return 0;
- nla_put_failure:
- return -1;
- }
- static const struct nla_policy icmp_nla_policy[CTA_PROTO_MAX+1] = {
- [CTA_PROTO_ICMP_TYPE] = { .type = NLA_U8 },
- [CTA_PROTO_ICMP_CODE] = { .type = NLA_U8 },
- [CTA_PROTO_ICMP_ID] = { .type = NLA_U16 },
- };
- static int icmp_nlattr_to_tuple(struct nlattr *tb[],
- struct nf_conntrack_tuple *tuple)
- {
- if (!tb[CTA_PROTO_ICMP_TYPE]
- || !tb[CTA_PROTO_ICMP_CODE]
- || !tb[CTA_PROTO_ICMP_ID])
- return -EINVAL;
- tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMP_TYPE]);
- tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMP_CODE]);
- tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMP_ID]);
- 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[] = {
- {
- .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[] = {
- {
- .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 __read_mostly =
- {
- .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,
- .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_nlattr = icmp_tuple_to_nlattr,
- .nlattr_to_tuple = icmp_nlattr_to_tuple,
- .nla_policy = icmp_nla_policy,
- #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
- };