diff options
Diffstat (limited to 'net/ipv4/netfilter/nf_conntrack_proto_icmp.c')
-rw-r--r-- | net/ipv4/netfilter/nf_conntrack_proto_icmp.c | 318 |
1 files changed, 318 insertions, 0 deletions
diff --git a/net/ipv4/netfilter/nf_conntrack_proto_icmp.c b/net/ipv4/netfilter/nf_conntrack_proto_icmp.c new file mode 100644 index 00000000..ab5b27a2 --- /dev/null +++ b/net/ipv4/netfilter/nf_conntrack_proto_icmp.c @@ -0,0 +1,318 @@ +/* (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_conntrack_zones.h> +#include <net/netfilter/nf_log.h> + +static unsigned int nf_ct_icmp_timeout __read_mostly = 30*HZ; + +static bool 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 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 +}; + +static bool 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 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; +} + +/* 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, + u_int8_t pf, + unsigned int hooknum) +{ + /* 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. */ + nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_icmp_timeout); + + return NF_ACCEPT; +} + +/* Called when a new connection for this protocol found. */ +static bool 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_ip(&ct->tuplehash[0].tuple); + return false; + } + return true; +} + +/* Returns conntrack if it dealt with ICMP, and filled in skb fields */ +static int +icmp_error_message(struct net *net, struct nf_conn *tmpl, 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; + u16 zone = tmpl ? nf_ct_zone(tmpl) : NF_CT_DEFAULT_ZONE; + + 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(net, zone, &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 net *net, struct nf_conn *tmpl, + struct sk_buff *skb, unsigned int dataoff, + enum ip_conntrack_info *ctinfo, u_int8_t 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(net, 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 (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING && + nf_ip_checksum(skb, hooknum, dataoff, 0)) { + if (LOG_INVALID(net, 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(net, 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(net, tmpl, 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; +} + +static int icmp_nlattr_tuple_size(void) +{ + return nla_policy_len(icmp_nla_policy, CTA_PROTO_MAX + 1); +} +#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, + }, + { } +}; +#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, + }, + { } +}; +#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_tuple_size = icmp_nlattr_tuple_size, + .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 +}; |