| /* (C) 1999-2001 Paul `Rusty' Russell |
| * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org> |
| * (C) 2006-2010 Patrick McHardy <kaber@trash.net> |
| * |
| * 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_conntrack_timeout.h> |
| #include <net/netfilter/nf_conntrack_zones.h> |
| #include <net/netfilter/nf_log.h> |
| |
| static const unsigned int nf_ct_icmp_timeout = 30*HZ; |
| |
| bool icmp_pkt_to_tuple(const struct sk_buff *skb, unsigned int dataoff, |
| struct net *net, 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 false; |
| |
| tuple->dst.u.icmp.type = hp->type; |
| tuple->src.u.icmp.id = hp->un.echo.id; |
| tuple->dst.u.icmp.code = hp->code; |
| |
| return true; |
| } |
| |
| /* 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 |
| }; |
| |
| bool nf_conntrack_invert_icmp_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 false; |
| |
| 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 true; |
| } |
| |
| /* Returns verdict for packet, or -1 for invalid. */ |
| int nf_conntrack_icmp_packet(struct nf_conn *ct, |
| struct sk_buff *skb, |
| enum ip_conntrack_info ctinfo, |
| const struct nf_hook_state *state) |
| { |
| /* Do not immediately delete the connection after the first |
| successful reply to avoid excessive conntrackd traffic |
| and also to handle correctly ICMP echo reply duplicates. */ |
| unsigned int *timeout = nf_ct_timeout_lookup(ct); |
| static const u_int8_t valid_new[] = { |
| [ICMP_ECHO] = 1, |
| [ICMP_TIMESTAMP] = 1, |
| [ICMP_INFO_REQUEST] = 1, |
| [ICMP_ADDRESS] = 1 |
| }; |
| |
| if (state->pf != NFPROTO_IPV4) |
| return -NF_ACCEPT; |
| |
| 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_ip(&ct->tuplehash[0].tuple); |
| return -NF_ACCEPT; |
| } |
| |
| if (!timeout) |
| timeout = &nf_icmp_pernet(nf_ct_net(ct))->timeout; |
| |
| nf_ct_refresh_acct(ct, ctinfo, skb, *timeout); |
| return NF_ACCEPT; |
| } |
| |
| /* Check inner header is related to any of the existing connections */ |
| int nf_conntrack_inet_error(struct nf_conn *tmpl, struct sk_buff *skb, |
| unsigned int dataoff, |
| const struct nf_hook_state *state, |
| u8 l4proto, union nf_inet_addr *outer_daddr) |
| { |
| struct nf_conntrack_tuple innertuple, origtuple; |
| const struct nf_conntrack_tuple_hash *h; |
| const struct nf_conntrack_zone *zone; |
| enum ip_conntrack_info ctinfo; |
| struct nf_conntrack_zone tmp; |
| union nf_inet_addr *ct_daddr; |
| enum ip_conntrack_dir dir; |
| struct nf_conn *ct; |
| |
| WARN_ON(skb_nfct(skb)); |
| zone = nf_ct_zone_tmpl(tmpl, skb, &tmp); |
| |
| /* Are they talking about one of our connections? */ |
| if (!nf_ct_get_tuplepr(skb, dataoff, |
| state->pf, state->net, &origtuple)) |
| 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)) |
| return -NF_ACCEPT; |
| |
| h = nf_conntrack_find_get(state->net, zone, &innertuple); |
| if (!h) |
| return -NF_ACCEPT; |
| |
| /* Consider: A -> T (=This machine) -> B |
| * Conntrack entry will look like this: |
| * Original: A->B |
| * Reply: B->T (SNAT case) OR A |
| * |
| * When this function runs, we got packet that looks like this: |
| * iphdr|icmphdr|inner_iphdr|l4header (tcp, udp, ..). |
| * |
| * Above nf_conntrack_find_get() makes lookup based on inner_hdr, |
| * so we should expect that destination of the found connection |
| * matches outer header destination address. |
| * |
| * In above example, we can consider these two cases: |
| * 1. Error coming in reply direction from B or M (middle box) to |
| * T (SNAT case) or A. |
| * Inner saddr will be B, dst will be T or A. |
| * The found conntrack will be reply tuple (B->T/A). |
| * 2. Error coming in original direction from A or M to B. |
| * Inner saddr will be A, inner daddr will be B. |
| * The found conntrack will be original tuple (A->B). |
| * |
| * In both cases, conntrack[dir].dst == inner.dst. |
| * |
| * A bogus packet could look like this: |
| * Inner: B->T |
| * Outer: B->X (other machine reachable by T). |
| * |
| * In this case, lookup yields connection A->B and will |
| * set packet from B->X as *RELATED*, even though no connection |
| * from X was ever seen. |
| */ |
| ct = nf_ct_tuplehash_to_ctrack(h); |
| dir = NF_CT_DIRECTION(h); |
| ct_daddr = &ct->tuplehash[dir].tuple.dst.u3; |
| if (!nf_inet_addr_cmp(outer_daddr, ct_daddr)) { |
| if (state->pf == AF_INET) { |
| nf_l4proto_log_invalid(skb, state->net, state->pf, |
| l4proto, |
| "outer daddr %pI4 != inner %pI4", |
| &outer_daddr->ip, &ct_daddr->ip); |
| } else if (state->pf == AF_INET6) { |
| nf_l4proto_log_invalid(skb, state->net, state->pf, |
| l4proto, |
| "outer daddr %pI6 != inner %pI6", |
| &outer_daddr->ip6, &ct_daddr->ip6); |
| } |
| nf_ct_put(ct); |
| return -NF_ACCEPT; |
| } |
| |
| ctinfo = IP_CT_RELATED; |
| if (dir == IP_CT_DIR_REPLY) |
| ctinfo += IP_CT_IS_REPLY; |
| |
| /* Update skb to refer to this connection */ |
| nf_ct_set(skb, ct, ctinfo); |
| return NF_ACCEPT; |
| } |
| |
| static void icmp_error_log(const struct sk_buff *skb, |
| const struct nf_hook_state *state, |
| const char *msg) |
| { |
| nf_l4proto_log_invalid(skb, state->net, state->pf, |
| IPPROTO_ICMP, "%s", msg); |
| } |
| |
| /* Small and modified version of icmp_rcv */ |
| int nf_conntrack_icmpv4_error(struct nf_conn *tmpl, |
| struct sk_buff *skb, unsigned int dataoff, |
| const struct nf_hook_state *state) |
| { |
| union nf_inet_addr outer_daddr; |
| const struct icmphdr *icmph; |
| struct icmphdr _ih; |
| |
| /* Not enough header? */ |
| icmph = skb_header_pointer(skb, dataoff, sizeof(_ih), &_ih); |
| if (icmph == NULL) { |
| icmp_error_log(skb, state, "short packet"); |
| return -NF_ACCEPT; |
| } |
| |
| /* See ip_conntrack_proto_tcp.c */ |
| if (state->net->ct.sysctl_checksum && |
| state->hook == NF_INET_PRE_ROUTING && |
| nf_ip_checksum(skb, state->hook, dataoff, 0)) { |
| icmp_error_log(skb, state, "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) { |
| icmp_error_log(skb, state, "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; |
| |
| memset(&outer_daddr, 0, sizeof(outer_daddr)); |
| outer_daddr.ip = ip_hdr(skb)->daddr; |
| |
| dataoff += sizeof(*icmph); |
| return nf_conntrack_inet_error(tmpl, skb, dataoff, state, |
| IPPROTO_ICMP, &outer_daddr); |
| } |
| |
| #if IS_ENABLED(CONFIG_NF_CT_NETLINK) |
| |
| #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) |
| { |
| if (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)) |
| goto nla_put_failure; |
| 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; |
| } |
| |
| static unsigned int icmp_nlattr_tuple_size(void) |
| { |
| static unsigned int size __read_mostly; |
| |
| if (!size) |
| size = nla_policy_len(icmp_nla_policy, CTA_PROTO_MAX + 1); |
| |
| return size; |
| } |
| #endif |
| |
| #ifdef CONFIG_NF_CONNTRACK_TIMEOUT |
| |
| #include <linux/netfilter/nfnetlink.h> |
| #include <linux/netfilter/nfnetlink_cttimeout.h> |
| |
| static int icmp_timeout_nlattr_to_obj(struct nlattr *tb[], |
| struct net *net, void *data) |
| { |
| unsigned int *timeout = data; |
| struct nf_icmp_net *in = nf_icmp_pernet(net); |
| |
| if (tb[CTA_TIMEOUT_ICMP_TIMEOUT]) { |
| if (!timeout) |
| timeout = &in->timeout; |
| *timeout = |
| ntohl(nla_get_be32(tb[CTA_TIMEOUT_ICMP_TIMEOUT])) * HZ; |
| } else if (timeout) { |
| /* Set default ICMP timeout. */ |
| *timeout = in->timeout; |
| } |
| return 0; |
| } |
| |
| static int |
| icmp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data) |
| { |
| const unsigned int *timeout = data; |
| |
| if (nla_put_be32(skb, CTA_TIMEOUT_ICMP_TIMEOUT, htonl(*timeout / HZ))) |
| goto nla_put_failure; |
| return 0; |
| |
| nla_put_failure: |
| return -ENOSPC; |
| } |
| |
| static const struct nla_policy |
| icmp_timeout_nla_policy[CTA_TIMEOUT_ICMP_MAX+1] = { |
| [CTA_TIMEOUT_ICMP_TIMEOUT] = { .type = NLA_U32 }, |
| }; |
| #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */ |
| |
| void nf_conntrack_icmp_init_net(struct net *net) |
| { |
| struct nf_icmp_net *in = nf_icmp_pernet(net); |
| |
| in->timeout = nf_ct_icmp_timeout; |
| } |
| |
| const struct nf_conntrack_l4proto nf_conntrack_l4proto_icmp = |
| { |
| .l4proto = IPPROTO_ICMP, |
| #if IS_ENABLED(CONFIG_NF_CT_NETLINK) |
| .tuple_to_nlattr = icmp_tuple_to_nlattr, |
| .nlattr_tuple_size = icmp_nlattr_tuple_size, |
| .nlattr_to_tuple = icmp_nlattr_to_tuple, |
| .nla_policy = icmp_nla_policy, |
| #endif |
| #ifdef CONFIG_NF_CONNTRACK_TIMEOUT |
| .ctnl_timeout = { |
| .nlattr_to_obj = icmp_timeout_nlattr_to_obj, |
| .obj_to_nlattr = icmp_timeout_obj_to_nlattr, |
| .nlattr_max = CTA_TIMEOUT_ICMP_MAX, |
| .obj_size = sizeof(unsigned int), |
| .nla_policy = icmp_timeout_nla_policy, |
| }, |
| #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */ |
| }; |