1/* (C) 1999-2001 Paul `Rusty' Russell 2 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org> 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License version 2 as 6 * published by the Free Software Foundation. 7 */ 8 9#include <linux/types.h> 10#include <linux/timer.h> 11#include <linux/netfilter.h> 12#include <linux/in.h> 13#include <linux/icmp.h> 14#include <linux/seq_file.h> 15#include <net/ip.h> 16#include <net/checksum.h> 17#include <linux/netfilter_ipv4.h> 18#include <net/netfilter/nf_conntrack_tuple.h> 19#include <net/netfilter/nf_conntrack_l4proto.h> 20#include <net/netfilter/nf_conntrack_core.h> 21#include <net/netfilter/nf_conntrack_zones.h> 22#include <net/netfilter/nf_log.h> 23 24static unsigned int nf_ct_icmp_timeout __read_mostly = 30*HZ; 25 26static bool icmp_pkt_to_tuple(const struct sk_buff *skb, unsigned int dataoff, 27 struct nf_conntrack_tuple *tuple) 28{ 29 const struct icmphdr *hp; 30 struct icmphdr _hdr; 31 32 hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr); 33 if (hp == NULL) 34 return false; 35 36 tuple->dst.u.icmp.type = hp->type; 37 tuple->src.u.icmp.id = hp->un.echo.id; 38 tuple->dst.u.icmp.code = hp->code; 39 40 return true; 41} 42 43/* Add 1; spaces filled with 0. */ 44static const u_int8_t invmap[] = { 45 [ICMP_ECHO] = ICMP_ECHOREPLY + 1, 46 [ICMP_ECHOREPLY] = ICMP_ECHO + 1, 47 [ICMP_TIMESTAMP] = ICMP_TIMESTAMPREPLY + 1, 48 [ICMP_TIMESTAMPREPLY] = ICMP_TIMESTAMP + 1, 49 [ICMP_INFO_REQUEST] = ICMP_INFO_REPLY + 1, 50 [ICMP_INFO_REPLY] = ICMP_INFO_REQUEST + 1, 51 [ICMP_ADDRESS] = ICMP_ADDRESSREPLY + 1, 52 [ICMP_ADDRESSREPLY] = ICMP_ADDRESS + 1 53}; 54 55static bool icmp_invert_tuple(struct nf_conntrack_tuple *tuple, 56 const struct nf_conntrack_tuple *orig) 57{ 58 if (orig->dst.u.icmp.type >= sizeof(invmap) || 59 !invmap[orig->dst.u.icmp.type]) 60 return false; 61 62 tuple->src.u.icmp.id = orig->src.u.icmp.id; 63 tuple->dst.u.icmp.type = invmap[orig->dst.u.icmp.type] - 1; 64 tuple->dst.u.icmp.code = orig->dst.u.icmp.code; 65 return true; 66} 67 68/* Print out the per-protocol part of the tuple. */ 69static int icmp_print_tuple(struct seq_file *s, 70 const struct nf_conntrack_tuple *tuple) 71{ 72 return seq_printf(s, "type=%u code=%u id=%u ", 73 tuple->dst.u.icmp.type, 74 tuple->dst.u.icmp.code, 75 ntohs(tuple->src.u.icmp.id)); 76} 77 78/* Returns verdict for packet, or -1 for invalid. */ 79static int icmp_packet(struct nf_conn *ct, 80 const struct sk_buff *skb, 81 unsigned int dataoff, 82 enum ip_conntrack_info ctinfo, 83 u_int8_t pf, 84 unsigned int hooknum) 85{ 86 /* Do not immediately delete the connection after the first 87 successful reply to avoid excessive conntrackd traffic 88 and also to handle correctly ICMP echo reply duplicates. */ 89 nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_icmp_timeout); 90 91 return NF_ACCEPT; 92} 93 94/* Called when a new connection for this protocol found. */ 95static bool icmp_new(struct nf_conn *ct, const struct sk_buff *skb, 96 unsigned int dataoff) 97{ 98 static const u_int8_t valid_new[] = { 99 [ICMP_ECHO] = 1, 100 [ICMP_TIMESTAMP] = 1, 101 [ICMP_INFO_REQUEST] = 1, 102 [ICMP_ADDRESS] = 1 103 }; 104 105 if (ct->tuplehash[0].tuple.dst.u.icmp.type >= sizeof(valid_new) || 106 !valid_new[ct->tuplehash[0].tuple.dst.u.icmp.type]) { 107 /* Can't create a new ICMP `conn' with this. */ 108 pr_debug("icmp: can't create new conn with type %u\n", 109 ct->tuplehash[0].tuple.dst.u.icmp.type); 110 nf_ct_dump_tuple_ip(&ct->tuplehash[0].tuple); 111 return false; 112 } 113 return true; 114} 115 116/* Returns conntrack if it dealt with ICMP, and filled in skb fields */ 117static int 118icmp_error_message(struct net *net, struct nf_conn *tmpl, struct sk_buff *skb, 119 enum ip_conntrack_info *ctinfo, 120 unsigned int hooknum) 121{ 122 struct nf_conntrack_tuple innertuple, origtuple; 123 const struct nf_conntrack_l4proto *innerproto; 124 const struct nf_conntrack_tuple_hash *h; 125 u16 zone = tmpl ? nf_ct_zone(tmpl) : NF_CT_DEFAULT_ZONE; 126 127 NF_CT_ASSERT(skb->nfct == NULL); 128 129 /* Are they talking about one of our connections? */ 130 if (!nf_ct_get_tuplepr(skb, 131 skb_network_offset(skb) + ip_hdrlen(skb) 132 + sizeof(struct icmphdr), 133 PF_INET, &origtuple)) { 134 pr_debug("icmp_error_message: failed to get tuple\n"); 135 return -NF_ACCEPT; 136 } 137 138 /* rcu_read_lock()ed by nf_hook_slow */ 139 innerproto = __nf_ct_l4proto_find(PF_INET, origtuple.dst.protonum); 140 141 /* Ordinarily, we'd expect the inverted tupleproto, but it's 142 been preserved inside the ICMP. */ 143 if (!nf_ct_invert_tuple(&innertuple, &origtuple, 144 &nf_conntrack_l3proto_ipv4, innerproto)) { 145 pr_debug("icmp_error_message: no match\n"); 146 return -NF_ACCEPT; 147 } 148 149 *ctinfo = IP_CT_RELATED; 150 151 h = nf_conntrack_find_get(net, zone, &innertuple); 152 if (!h) { 153 pr_debug("icmp_error_message: no match\n"); 154 return -NF_ACCEPT; 155 } 156 157 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY) 158 *ctinfo += IP_CT_IS_REPLY; 159 160 /* Update skb to refer to this connection */ 161 skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general; 162 skb->nfctinfo = *ctinfo; 163 return -NF_ACCEPT; 164} 165 166/* Small and modified version of icmp_rcv */ 167static int 168icmp_error(struct net *net, struct nf_conn *tmpl, 169 struct sk_buff *skb, unsigned int dataoff, 170 enum ip_conntrack_info *ctinfo, u_int8_t pf, unsigned int hooknum) 171{ 172 const struct icmphdr *icmph; 173 struct icmphdr _ih; 174 175 /* Not enough header? */ 176 icmph = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_ih), &_ih); 177 if (icmph == NULL) { 178 if (LOG_INVALID(net, IPPROTO_ICMP)) 179 nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL, 180 "nf_ct_icmp: short packet "); 181 return -NF_ACCEPT; 182 } 183 184 /* See ip_conntrack_proto_tcp.c */ 185 if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING && 186 nf_ip_checksum(skb, hooknum, dataoff, 0)) { 187 if (LOG_INVALID(net, IPPROTO_ICMP)) 188 nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL, 189 "nf_ct_icmp: bad HW ICMP checksum "); 190 return -NF_ACCEPT; 191 } 192 193 /* 194 * 18 is the highest 'known' ICMP type. Anything else is a mystery 195 * 196 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently 197 * discarded. 198 */ 199 if (icmph->type > NR_ICMP_TYPES) { 200 if (LOG_INVALID(net, IPPROTO_ICMP)) 201 nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL, 202 "nf_ct_icmp: invalid ICMP type "); 203 return -NF_ACCEPT; 204 } 205 206 /* Need to track icmp error message? */ 207 if (icmph->type != ICMP_DEST_UNREACH && 208 icmph->type != ICMP_SOURCE_QUENCH && 209 icmph->type != ICMP_TIME_EXCEEDED && 210 icmph->type != ICMP_PARAMETERPROB && 211 icmph->type != ICMP_REDIRECT) 212 return NF_ACCEPT; 213 214 return icmp_error_message(net, tmpl, skb, ctinfo, hooknum); 215} 216 217#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE) 218 219#include <linux/netfilter/nfnetlink.h> 220#include <linux/netfilter/nfnetlink_conntrack.h> 221 222static int icmp_tuple_to_nlattr(struct sk_buff *skb, 223 const struct nf_conntrack_tuple *t) 224{ 225 NLA_PUT_BE16(skb, CTA_PROTO_ICMP_ID, t->src.u.icmp.id); 226 NLA_PUT_U8(skb, CTA_PROTO_ICMP_TYPE, t->dst.u.icmp.type); 227 NLA_PUT_U8(skb, CTA_PROTO_ICMP_CODE, t->dst.u.icmp.code); 228 229 return 0; 230 231nla_put_failure: 232 return -1; 233} 234 235static const struct nla_policy icmp_nla_policy[CTA_PROTO_MAX+1] = { 236 [CTA_PROTO_ICMP_TYPE] = { .type = NLA_U8 }, 237 [CTA_PROTO_ICMP_CODE] = { .type = NLA_U8 }, 238 [CTA_PROTO_ICMP_ID] = { .type = NLA_U16 }, 239}; 240 241static int icmp_nlattr_to_tuple(struct nlattr *tb[], 242 struct nf_conntrack_tuple *tuple) 243{ 244 if (!tb[CTA_PROTO_ICMP_TYPE] || 245 !tb[CTA_PROTO_ICMP_CODE] || 246 !tb[CTA_PROTO_ICMP_ID]) 247 return -EINVAL; 248 249 tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMP_TYPE]); 250 tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMP_CODE]); 251 tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMP_ID]); 252 253 if (tuple->dst.u.icmp.type >= sizeof(invmap) || 254 !invmap[tuple->dst.u.icmp.type]) 255 return -EINVAL; 256 257 return 0; 258} 259 260static int icmp_nlattr_tuple_size(void) 261{ 262 return nla_policy_len(icmp_nla_policy, CTA_PROTO_MAX + 1); 263} 264#endif 265 266#ifdef CONFIG_SYSCTL 267static struct ctl_table_header *icmp_sysctl_header; 268static struct ctl_table icmp_sysctl_table[] = { 269 { 270 .procname = "nf_conntrack_icmp_timeout", 271 .data = &nf_ct_icmp_timeout, 272 .maxlen = sizeof(unsigned int), 273 .mode = 0644, 274 .proc_handler = proc_dointvec_jiffies, 275 }, 276 { } 277}; 278#ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT 279static struct ctl_table icmp_compat_sysctl_table[] = { 280 { 281 .procname = "ip_conntrack_icmp_timeout", 282 .data = &nf_ct_icmp_timeout, 283 .maxlen = sizeof(unsigned int), 284 .mode = 0644, 285 .proc_handler = proc_dointvec_jiffies, 286 }, 287 { } 288}; 289#endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */ 290#endif /* CONFIG_SYSCTL */ 291 292struct nf_conntrack_l4proto nf_conntrack_l4proto_icmp __read_mostly = 293{ 294 .l3proto = PF_INET, 295 .l4proto = IPPROTO_ICMP, 296 .name = "icmp", 297 .pkt_to_tuple = icmp_pkt_to_tuple, 298 .invert_tuple = icmp_invert_tuple, 299 .print_tuple = icmp_print_tuple, 300 .packet = icmp_packet, 301 .new = icmp_new, 302 .error = icmp_error, 303 .destroy = NULL, 304 .me = NULL, 305#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE) 306 .tuple_to_nlattr = icmp_tuple_to_nlattr, 307 .nlattr_tuple_size = icmp_nlattr_tuple_size, 308 .nlattr_to_tuple = icmp_nlattr_to_tuple, 309 .nla_policy = icmp_nla_policy, 310#endif 311#ifdef CONFIG_SYSCTL 312 .ctl_table_header = &icmp_sysctl_header, 313 .ctl_table = icmp_sysctl_table, 314#ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT 315 .ctl_compat_table = icmp_compat_sysctl_table, 316#endif 317#endif 318}; 319