| /* (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/sched.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_protocol.h> |
| #include <net/netfilter/nf_conntrack_core.h> |
| |
| unsigned long nf_ct_icmp_timeout = 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_protocol *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; |
| } |
| |
| innerproto = __nf_ct_proto_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 (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 = |
| *(u_int16_t *)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 |
| |
| struct nf_conntrack_protocol nf_conntrack_protocol_icmp = |
| { |
| .list = { NULL, NULL }, |
| .l3proto = PF_INET, |
| .proto = 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 |
| }; |
| |
| EXPORT_SYMBOL(nf_conntrack_protocol_icmp); |